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libpcap-1.7.0
pcap-linux.c
6 259 строк
173 KB
Denis Ovsienko
fix compiling with SO_BPF_EXTENSIONS
11 ноя 2014, 00:06
11 ноя 2014, 00:06
32527e5
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/* * pcap-linux.c: Packet capture interface to the Linux kernel * * Copyright (c) 2000 Torsten Landschoff <torsten@debian.org> * Sebastian Krahmer <krahmer@cs.uni-potsdam.de> * * License: BSD * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * 3. The names of the authors may not be used to endorse or promote * products derived from this software without specific prior * written permission. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. * * Modifications: Added PACKET_MMAP support * Paolo Abeni <paolo.abeni@email.it> * Added TPACKET_V3 support * Gabor Tatarka <gabor.tatarka@ericsson.com> * * based on previous works of: * Simon Patarin <patarin@cs.unibo.it> * Phil Wood <cpw@lanl.gov> * * Monitor-mode support for mac80211 includes code taken from the iw * command; the copyright notice for that code is * * Copyright (c) 2007, 2008 Johannes Berg * Copyright (c) 2007 Andy Lutomirski * Copyright (c) 2007 Mike Kershaw * Copyright (c) 2008 Gábor Stefanik * * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * Known problems with 2.0[.x] kernels: * * - The loopback device gives every packet twice; on 2.2[.x] kernels, * if we use PF_PACKET, we can filter out the transmitted version * of the packet by using data in the "sockaddr_ll" returned by * "recvfrom()", but, on 2.0[.x] kernels, we have to use * PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a * "sockaddr_pkt" which doesn't give us enough information to let * us do that. * * - We have to set the interface's IFF_PROMISC flag ourselves, if * we're to run in promiscuous mode, which means we have to turn * it off ourselves when we're done; the kernel doesn't keep track * of how many sockets are listening promiscuously, which means * it won't get turned off automatically when no sockets are * listening promiscuously. We catch "pcap_close()" and, for * interfaces we put into promiscuous mode, take them out of * promiscuous mode - which isn't necessarily the right thing to * do, if another socket also requested promiscuous mode between * the time when we opened the socket and the time when we close * the socket. * * - MSG_TRUNC isn't supported, so you can't specify that "recvfrom()" * return the amount of data that you could have read, rather than * the amount that was returned, so we can't just allocate a buffer * whose size is the snapshot length and pass the snapshot length * as the byte count, and also pass MSG_TRUNC, so that the return * value tells us how long the packet was on the wire. * * This means that, if we want to get the actual size of the packet, * so we can return it in the "len" field of the packet header, * we have to read the entire packet, not just the part that fits * within the snapshot length, and thus waste CPU time copying data * from the kernel that our caller won't see. * * We have to get the actual size, and supply it in "len", because * otherwise, the IP dissector in tcpdump, for example, will complain * about "truncated-ip", as the packet will appear to have been * shorter, on the wire, than the IP header said it should have been. */ #define _GNU_SOURCE #ifdef HAVE_CONFIG_H #include "config.h" #endif #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <ctype.h> #include <unistd.h> #include <fcntl.h> #include <string.h> #include <limits.h> #include <sys/stat.h> #include <sys/socket.h> #include <sys/ioctl.h> #include <sys/utsname.h> #include <sys/mman.h> #include <linux/if.h> #include <linux/if_packet.h> #include <linux/sockios.h> #include <netinet/in.h> #include <linux/if_ether.h> #include <net/if_arp.h> #include <poll.h> #include <dirent.h> #include "pcap-int.h" #include "pcap/sll.h" #include "pcap/vlan.h" /* * If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET * sockets rather than SOCK_PACKET sockets. * * To use them, we include <linux/if_packet.h> rather than * <netpacket/packet.h>; we do so because * * some Linux distributions (e.g., Slackware 4.0) have 2.2 or * later kernels and libc5, and don't provide a <netpacket/packet.h> * file; * * not all versions of glibc2 have a <netpacket/packet.h> file * that defines stuff needed for some of the 2.4-or-later-kernel * features, so if the system has a 2.4 or later kernel, we * still can't use those features. * * We're already including a number of other <linux/XXX.h> headers, and * this code is Linux-specific (no other OS has PF_PACKET sockets as * a raw packet capture mechanism), so it's not as if you gain any * useful portability by using <netpacket/packet.h> * * XXX - should we just include <linux/if_packet.h> even if PF_PACKET * isn't defined? It only defines one data structure in 2.0.x, so * it shouldn't cause any problems. */ #ifdef PF_PACKET # include <linux/if_packet.h> /* * On at least some Linux distributions (for example, Red Hat 5.2), * there's no <netpacket/packet.h> file, but PF_PACKET is defined if * you include <sys/socket.h>, but <linux/if_packet.h> doesn't define * any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of * the PACKET_xxx stuff. * * So we check whether PACKET_HOST is defined, and assume that we have * PF_PACKET sockets only if it is defined. */ # ifdef PACKET_HOST # define HAVE_PF_PACKET_SOCKETS # ifdef PACKET_AUXDATA # define HAVE_PACKET_AUXDATA # endif /* PACKET_AUXDATA */ # endif /* PACKET_HOST */ /* check for memory mapped access avaibility. We assume every needed * struct is defined if the macro TPACKET_HDRLEN is defined, because it * uses many ring related structs and macros */ # ifdef TPACKET_HDRLEN # define HAVE_PACKET_RING # ifdef TPACKET3_HDRLEN # define HAVE_TPACKET3 # endif /* TPACKET3_HDRLEN */ # ifdef TPACKET2_HDRLEN # define HAVE_TPACKET2 # else /* TPACKET2_HDRLEN */ # define TPACKET_V1 0 /* Old kernel with only V1, so no TPACKET_Vn defined */ # endif /* TPACKET2_HDRLEN */ # endif /* TPACKET_HDRLEN */ #endif /* PF_PACKET */ #ifdef SO_ATTACH_FILTER #include <linux/types.h> #include <linux/filter.h> #endif #ifdef HAVE_LINUX_NET_TSTAMP_H #include <linux/net_tstamp.h> #endif /* * Got Wireless Extensions? */ #ifdef HAVE_LINUX_WIRELESS_H #include <linux/wireless.h> #endif /* HAVE_LINUX_WIRELESS_H */ /* * Got libnl? */ #ifdef HAVE_LIBNL #include <linux/nl80211.h> #include <netlink/genl/genl.h> #include <netlink/genl/family.h> #include <netlink/genl/ctrl.h> #include <netlink/msg.h> #include <netlink/attr.h> #endif /* HAVE_LIBNL */ /* * Got ethtool support? */ #ifdef HAVE_LINUX_ETHTOOL_H #include <linux/ethtool.h> #endif #ifndef HAVE_SOCKLEN_T typedef int socklen_t; #endif #ifndef MSG_TRUNC /* * This is being compiled on a system that lacks MSG_TRUNC; define it * with the value it has in the 2.2 and later kernels, so that, on * those kernels, when we pass it in the flags argument to "recvfrom()" * we're passing the right value and thus get the MSG_TRUNC behavior * we want. (We don't get that behavior on 2.0[.x] kernels, because * they didn't support MSG_TRUNC.) */ #define MSG_TRUNC 0x20 #endif #ifndef SOL_PACKET /* * This is being compiled on a system that lacks SOL_PACKET; define it * with the value it has in the 2.2 and later kernels, so that we can * set promiscuous mode in the good modern way rather than the old * 2.0-kernel crappy way. */ #define SOL_PACKET 263 #endif #define MAX_LINKHEADER_SIZE 256 /* * When capturing on all interfaces we use this as the buffer size. * Should be bigger then all MTUs that occur in real life. * 64kB should be enough for now. */ #define BIGGER_THAN_ALL_MTUS (64*1024) /* * Private data for capturing on Linux SOCK_PACKET or PF_PACKET sockets. */ struct pcap_linux { u_int packets_read; /* count of packets read with recvfrom() */ long proc_dropped; /* packets reported dropped by /proc/net/dev */ struct pcap_stat stat; char *device; /* device name */ int filter_in_userland; /* must filter in userland */ int blocks_to_filter_in_userland; int must_do_on_close; /* stuff we must do when we close */ int timeout; /* timeout for buffering */ int sock_packet; /* using Linux 2.0 compatible interface */ int cooked; /* using SOCK_DGRAM rather than SOCK_RAW */ int ifindex; /* interface index of device we're bound to */ int lo_ifindex; /* interface index of the loopback device */ bpf_u_int32 oldmode; /* mode to restore when turning monitor mode off */ char *mondevice; /* mac80211 monitor device we created */ u_char *mmapbuf; /* memory-mapped region pointer */ size_t mmapbuflen; /* size of region */ int vlan_offset; /* offset at which to insert vlan tags; if -1, don't insert */ u_int tp_version; /* version of tpacket_hdr for mmaped ring */ u_int tp_hdrlen; /* hdrlen of tpacket_hdr for mmaped ring */ u_char *oneshot_buffer; /* buffer for copy of packet */ #ifdef HAVE_TPACKET3 unsigned char *current_packet; /* Current packet within the TPACKET_V3 block. Move to next block if NULL. */ int packets_left; /* Unhandled packets left within the block from previous call to pcap_read_linux_mmap_v3 in case of TPACKET_V3. */ #endif }; /* * Stuff to do when we close. */ #define MUST_CLEAR_PROMISC 0x00000001 /* clear promiscuous mode */ #define MUST_CLEAR_RFMON 0x00000002 /* clear rfmon (monitor) mode */ #define MUST_DELETE_MONIF 0x00000004 /* delete monitor-mode interface */ /* * Prototypes for internal functions and methods. */ static void map_arphrd_to_dlt(pcap_t *, int, const char *, int); #ifdef HAVE_PF_PACKET_SOCKETS static short int map_packet_type_to_sll_type(short int); #endif static int pcap_activate_linux(pcap_t *); static int activate_old(pcap_t *); static int activate_new(pcap_t *); static int activate_mmap(pcap_t *, int *); static int pcap_can_set_rfmon_linux(pcap_t *); static int pcap_read_linux(pcap_t *, int, pcap_handler, u_char *); static int pcap_read_packet(pcap_t *, pcap_handler, u_char *); static int pcap_inject_linux(pcap_t *, const void *, size_t); static int pcap_stats_linux(pcap_t *, struct pcap_stat *); static int pcap_setfilter_linux(pcap_t *, struct bpf_program *); static int pcap_setdirection_linux(pcap_t *, pcap_direction_t); static int pcap_set_datalink_linux(pcap_t *, int); static void pcap_cleanup_linux(pcap_t *); union thdr { struct tpacket_hdr *h1; #ifdef HAVE_TPACKET2 struct tpacket2_hdr *h2; #endif #ifdef HAVE_TPACKET3 struct tpacket_block_desc *h3; #endif void *raw; }; #ifdef HAVE_PACKET_RING #define RING_GET_FRAME(h) (((union thdr **)h->buffer)[h->offset]) static void destroy_ring(pcap_t *handle); static int create_ring(pcap_t *handle, int *status); static int prepare_tpacket_socket(pcap_t *handle); static void pcap_cleanup_linux_mmap(pcap_t *); static int pcap_read_linux_mmap_v1(pcap_t *, int, pcap_handler , u_char *); #ifdef HAVE_TPACKET2 static int pcap_read_linux_mmap_v2(pcap_t *, int, pcap_handler , u_char *); #endif #ifdef HAVE_TPACKET3 static int pcap_read_linux_mmap_v3(pcap_t *, int, pcap_handler , u_char *); #endif static int pcap_setfilter_linux_mmap(pcap_t *, struct bpf_program *); static int pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf); static int pcap_getnonblock_mmap(pcap_t *p, char *errbuf); static void pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h, const u_char *bytes); #endif /* * Wrap some ioctl calls */ #ifdef HAVE_PF_PACKET_SOCKETS static int iface_get_id(int fd, const char *device, char *ebuf); #endif /* HAVE_PF_PACKET_SOCKETS */ static int iface_get_mtu(int fd, const char *device, char *ebuf); static int iface_get_arptype(int fd, const char *device, char *ebuf); #ifdef HAVE_PF_PACKET_SOCKETS static int iface_bind(int fd, int ifindex, char *ebuf); #ifdef IW_MODE_MONITOR static int has_wext(int sock_fd, const char *device, char *ebuf); #endif /* IW_MODE_MONITOR */ static int enter_rfmon_mode(pcap_t *handle, int sock_fd, const char *device); #endif /* HAVE_PF_PACKET_SOCKETS */ #if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) static int iface_ethtool_get_ts_info(pcap_t *handle, char *ebuf); #endif static int iface_get_offload(pcap_t *handle); static int iface_bind_old(int fd, const char *device, char *ebuf); #ifdef SO_ATTACH_FILTER static int fix_program(pcap_t *handle, struct sock_fprog *fcode, int is_mapped); static int fix_offset(struct bpf_insn *p); static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode); static int reset_kernel_filter(pcap_t *handle); static struct sock_filter total_insn = BPF_STMT(BPF_RET | BPF_K, 0); static struct sock_fprog total_fcode = { 1, &total_insn }; #endif /* SO_ATTACH_FILTER */ pcap_t * pcap_create_interface(const char *device, char *ebuf) { pcap_t *handle; handle = pcap_create_common(device, ebuf, sizeof (struct pcap_linux)); if (handle == NULL) return NULL; handle->activate_op = pcap_activate_linux; handle->can_set_rfmon_op = pcap_can_set_rfmon_linux; #if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) /* * See what time stamp types we support. */ if (iface_ethtool_get_ts_info(handle, ebuf) == -1) { free(handle); return NULL; } #endif #if defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS) /* * We claim that we support microsecond and nanosecond time * stamps. * * XXX - with adapter-supplied time stamps, can we choose * microsecond or nanosecond time stamps on arbitrary * adapters? */ handle->tstamp_precision_count = 2; handle->tstamp_precision_list = malloc(2 * sizeof(u_int)); if (handle->tstamp_precision_list == NULL) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s", pcap_strerror(errno)); if (handle->tstamp_type_list != NULL) free(handle->tstamp_type_list); free(handle); return NULL; } handle->tstamp_precision_list[0] = PCAP_TSTAMP_PRECISION_MICRO; handle->tstamp_precision_list[1] = PCAP_TSTAMP_PRECISION_NANO; #endif /* defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS) */ return handle; } #ifdef HAVE_LIBNL /* * If interface {if} is a mac80211 driver, the file * /sys/class/net/{if}/phy80211 is a symlink to * /sys/class/ieee80211/{phydev}, for some {phydev}. * * On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at * least, has a "wmaster0" device and a "wlan0" device; the * latter is the one with the IP address. Both show up in * "tcpdump -D" output. Capturing on the wmaster0 device * captures with 802.11 headers. * * airmon-ng searches through /sys/class/net for devices named * monN, starting with mon0; as soon as one *doesn't* exist, * it chooses that as the monitor device name. If the "iw" * command exists, it does "iw dev {if} interface add {monif} * type monitor", where {monif} is the monitor device. It * then (sigh) sleeps .1 second, and then configures the * device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface * is a file, it writes {mondev}, without a newline, to that file, * and again (sigh) sleeps .1 second, and then iwconfig's that * device into monitor mode and configures it up. Otherwise, * you can't do monitor mode. * * All these devices are "glued" together by having the * /sys/class/net/{device}/phy80211 links pointing to the same * place, so, given a wmaster, wlan, or mon device, you can * find the other devices by looking for devices with * the same phy80211 link. * * To turn monitor mode off, delete the monitor interface, * either with "iw dev {monif} interface del" or by sending * {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface * * Note: if you try to create a monitor device named "monN", and * there's already a "monN" device, it fails, as least with * the netlink interface (which is what iw uses), with a return * value of -ENFILE. (Return values are negative errnos.) We * could probably use that to find an unused device. * * Yes, you can have multiple monitor devices for a given * physical device. */ /* * Is this a mac80211 device? If so, fill in the physical device path and * return 1; if not, return 0. On an error, fill in handle->errbuf and * return PCAP_ERROR. */ static int get_mac80211_phydev(pcap_t *handle, const char *device, char *phydev_path, size_t phydev_max_pathlen) { char *pathstr; ssize_t bytes_read; /* * Generate the path string for the symlink to the physical device. */ if (asprintf(&pathstr, "/sys/class/net/%s/phy80211", device) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: Can't generate path name string for /sys/class/net device", device); return PCAP_ERROR; } bytes_read = readlink(pathstr, phydev_path, phydev_max_pathlen); if (bytes_read == -1) { if (errno == ENOENT || errno == EINVAL) { /* * Doesn't exist, or not a symlink; assume that * means it's not a mac80211 device. */ free(pathstr); return 0; } snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: Can't readlink %s: %s", device, pathstr, strerror(errno)); free(pathstr); return PCAP_ERROR; } free(pathstr); phydev_path[bytes_read] = '\0'; return 1; } #ifdef HAVE_LIBNL_SOCKETS #define get_nl_errmsg nl_geterror #else /* libnl 2.x compatibility code */ #define nl_sock nl_handle static inline struct nl_handle * nl_socket_alloc(void) { return nl_handle_alloc(); } static inline void nl_socket_free(struct nl_handle *h) { nl_handle_destroy(h); } #define get_nl_errmsg strerror static inline int __genl_ctrl_alloc_cache(struct nl_handle *h, struct nl_cache **cache) { struct nl_cache *tmp = genl_ctrl_alloc_cache(h); if (!tmp) return -ENOMEM; *cache = tmp; return 0; } #define genl_ctrl_alloc_cache __genl_ctrl_alloc_cache #endif /* !HAVE_LIBNL_SOCKETS */ struct nl80211_state { struct nl_sock *nl_sock; struct nl_cache *nl_cache; struct genl_family *nl80211; }; static int nl80211_init(pcap_t *handle, struct nl80211_state *state, const char *device) { int err; state->nl_sock = nl_socket_alloc(); if (!state->nl_sock) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: failed to allocate netlink handle", device); return PCAP_ERROR; } if (genl_connect(state->nl_sock)) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: failed to connect to generic netlink", device); goto out_handle_destroy; } err = genl_ctrl_alloc_cache(state->nl_sock, &state->nl_cache); if (err < 0) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: failed to allocate generic netlink cache: %s", device, get_nl_errmsg(-err)); goto out_handle_destroy; } state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211"); if (!state->nl80211) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: nl80211 not found", device); goto out_cache_free; } return 0; out_cache_free: nl_cache_free(state->nl_cache); out_handle_destroy: nl_socket_free(state->nl_sock); return PCAP_ERROR; } static void nl80211_cleanup(struct nl80211_state *state) { genl_family_put(state->nl80211); nl_cache_free(state->nl_cache); nl_socket_free(state->nl_sock); } static int add_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, const char *device, const char *mondevice) { int ifindex; struct nl_msg *msg; int err; ifindex = iface_get_id(sock_fd, device, handle->errbuf); if (ifindex == -1) return PCAP_ERROR; msg = nlmsg_alloc(); if (!msg) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: failed to allocate netlink msg", device); return PCAP_ERROR; } genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0, 0, NL80211_CMD_NEW_INTERFACE, 0); NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex); NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, mondevice); NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR); err = nl_send_auto_complete(state->nl_sock, msg); if (err < 0) { #if defined HAVE_LIBNL_NLE if (err == -NLE_FAILURE) { #else if (err == -ENFILE) { #endif /* * Device not available; our caller should just * keep trying. (libnl 2.x maps ENFILE to * NLE_FAILURE; it can also map other errors * to that, but there's not much we can do * about that.) */ nlmsg_free(msg); return 0; } else { /* * Real failure, not just "that device is not * available. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: nl_send_auto_complete failed adding %s interface: %s", device, mondevice, get_nl_errmsg(-err)); nlmsg_free(msg); return PCAP_ERROR; } } err = nl_wait_for_ack(state->nl_sock); if (err < 0) { #if defined HAVE_LIBNL_NLE if (err == -NLE_FAILURE) { #else if (err == -ENFILE) { #endif /* * Device not available; our caller should just * keep trying. (libnl 2.x maps ENFILE to * NLE_FAILURE; it can also map other errors * to that, but there's not much we can do * about that.) */ nlmsg_free(msg); return 0; } else { /* * Real failure, not just "that device is not * available. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: nl_wait_for_ack failed adding %s interface: %s", device, mondevice, get_nl_errmsg(-err)); nlmsg_free(msg); return PCAP_ERROR; } } /* * Success. */ nlmsg_free(msg); return 1; nla_put_failure: snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: nl_put failed adding %s interface", device, mondevice); nlmsg_free(msg); return PCAP_ERROR; } static int del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, const char *device, const char *mondevice) { int ifindex; struct nl_msg *msg; int err; ifindex = iface_get_id(sock_fd, mondevice, handle->errbuf); if (ifindex == -1) return PCAP_ERROR; msg = nlmsg_alloc(); if (!msg) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: failed to allocate netlink msg", device); return PCAP_ERROR; } genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0, 0, NL80211_CMD_DEL_INTERFACE, 0); NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex); err = nl_send_auto_complete(state->nl_sock, msg); if (err < 0) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: nl_send_auto_complete failed deleting %s interface: %s", device, mondevice, get_nl_errmsg(-err)); nlmsg_free(msg); return PCAP_ERROR; } err = nl_wait_for_ack(state->nl_sock); if (err < 0) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: nl_wait_for_ack failed adding %s interface: %s", device, mondevice, get_nl_errmsg(-err)); nlmsg_free(msg); return PCAP_ERROR; } /* * Success. */ nlmsg_free(msg); return 1; nla_put_failure: snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: nl_put failed deleting %s interface", device, mondevice); nlmsg_free(msg); return PCAP_ERROR; } static int enter_rfmon_mode_mac80211(pcap_t *handle, int sock_fd, const char *device) { struct pcap_linux *handlep = handle->priv; int ret; char phydev_path[PATH_MAX+1]; struct nl80211_state nlstate; struct ifreq ifr; u_int n; /* * Is this a mac80211 device? */ ret = get_mac80211_phydev(handle, device, phydev_path, PATH_MAX); if (ret < 0) return ret; /* error */ if (ret == 0) return 0; /* no error, but not mac80211 device */ /* * XXX - is this already a monN device? * If so, we're done. * Is that determined by old Wireless Extensions ioctls? */ /* * OK, it's apparently a mac80211 device. * Try to find an unused monN device for it. */ ret = nl80211_init(handle, &nlstate, device); if (ret != 0) return ret; for (n = 0; n < UINT_MAX; n++) { /* * Try mon{n}. */ char mondevice[3+10+1]; /* mon{UINT_MAX}\0 */ snprintf(mondevice, sizeof mondevice, "mon%u", n); ret = add_mon_if(handle, sock_fd, &nlstate, device, mondevice); if (ret == 1) { handlep->mondevice = strdup(mondevice); goto added; } if (ret < 0) { /* * Hard failure. Just return ret; handle->errbuf * has already been set. */ nl80211_cleanup(&nlstate); return ret; } } snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: No free monN interfaces", device); nl80211_cleanup(&nlstate); return PCAP_ERROR; added: #if 0 /* * Sleep for .1 seconds. */ delay.tv_sec = 0; delay.tv_nsec = 500000000; nanosleep(&delay, NULL); #endif /* * If we haven't already done so, arrange to have * "pcap_close_all()" called when we exit. */ if (!pcap_do_addexit(handle)) { /* * "atexit()" failed; don't put the interface * in rfmon mode, just give up. */ return PCAP_ERROR_RFMON_NOTSUP; } /* * Now configure the monitor interface up. */ memset(&ifr, 0, sizeof(ifr)); strlcpy(ifr.ifr_name, handlep->mondevice, sizeof(ifr.ifr_name)); if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: Can't get flags for %s: %s", device, handlep->mondevice, strerror(errno)); del_mon_if(handle, sock_fd, &nlstate, device, handlep->mondevice); nl80211_cleanup(&nlstate); return PCAP_ERROR; } ifr.ifr_flags |= IFF_UP|IFF_RUNNING; if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: Can't set flags for %s: %s", device, handlep->mondevice, strerror(errno)); del_mon_if(handle, sock_fd, &nlstate, device, handlep->mondevice); nl80211_cleanup(&nlstate); return PCAP_ERROR; } /* * Success. Clean up the libnl state. */ nl80211_cleanup(&nlstate); /* * Note that we have to delete the monitor device when we close * the handle. */ handlep->must_do_on_close |= MUST_DELETE_MONIF; /* * Add this to the list of pcaps to close when we exit. */ pcap_add_to_pcaps_to_close(handle); return 1; } #endif /* HAVE_LIBNL */ static int pcap_can_set_rfmon_linux(pcap_t *handle) { #ifdef HAVE_LIBNL char phydev_path[PATH_MAX+1]; int ret; #endif #ifdef IW_MODE_MONITOR int sock_fd; struct iwreq ireq; #endif if (strcmp(handle->opt.source, "any") == 0) { /* * Monitor mode makes no sense on the "any" device. */ return 0; } #ifdef HAVE_LIBNL /* * Bleah. There doesn't seem to be a way to ask a mac80211 * device, through libnl, whether it supports monitor mode; * we'll just check whether the device appears to be a * mac80211 device and, if so, assume the device supports * monitor mode. * * wmaster devices don't appear to support the Wireless * Extensions, but we can create a mon device for a * wmaster device, so we don't bother checking whether * a mac80211 device supports the Wireless Extensions. */ ret = get_mac80211_phydev(handle, handle->opt.source, phydev_path, PATH_MAX); if (ret < 0) return ret; /* error */ if (ret == 1) return 1; /* mac80211 device */ #endif #ifdef IW_MODE_MONITOR /* * Bleah. There doesn't appear to be an ioctl to use to ask * whether a device supports monitor mode; we'll just do * SIOCGIWMODE and, if it succeeds, assume the device supports * monitor mode. * * Open a socket on which to attempt to get the mode. * (We assume that if we have Wireless Extensions support * we also have PF_PACKET support.) */ sock_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); if (sock_fd == -1) { (void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "socket: %s", pcap_strerror(errno)); return PCAP_ERROR; } /* * Attempt to get the current mode. */ strlcpy(ireq.ifr_ifrn.ifrn_name, handle->opt.source, sizeof ireq.ifr_ifrn.ifrn_name); if (ioctl(sock_fd, SIOCGIWMODE, &ireq) != -1) { /* * Well, we got the mode; assume we can set it. */ close(sock_fd); return 1; } if (errno == ENODEV) { /* The device doesn't even exist. */ (void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SIOCGIWMODE failed: %s", pcap_strerror(errno)); close(sock_fd); return PCAP_ERROR_NO_SUCH_DEVICE; } close(sock_fd); #endif return 0; } /* * Grabs the number of dropped packets by the interface from /proc/net/dev. * * XXX - what about /sys/class/net/{interface name}/rx_*? There are * individual devices giving, in ASCII, various rx_ and tx_ statistics. * * Or can we get them in binary form from netlink? */ static long int linux_if_drops(const char * if_name) { char buffer[512]; char * bufptr; FILE * file; int field_to_convert = 3, if_name_sz = strlen(if_name); long int dropped_pkts = 0; file = fopen("/proc/net/dev", "r"); if (!file) return 0; while (!dropped_pkts && fgets( buffer, sizeof(buffer), file )) { /* search for 'bytes' -- if its in there, then that means we need to grab the fourth field. otherwise grab the third field. */ if (field_to_convert != 4 && strstr(buffer, "bytes")) { field_to_convert = 4; continue; } /* find iface and make sure it actually matches -- space before the name and : after it */ if ((bufptr = strstr(buffer, if_name)) && (bufptr == buffer || *(bufptr-1) == ' ') && *(bufptr + if_name_sz) == ':') { bufptr = bufptr + if_name_sz + 1; /* grab the nth field from it */ while( --field_to_convert && *bufptr != '\0') { while (*bufptr != '\0' && *(bufptr++) == ' '); while (*bufptr != '\0' && *(bufptr++) != ' '); } /* get rid of any final spaces */ while (*bufptr != '\0' && *bufptr == ' ') bufptr++; if (*bufptr != '\0') dropped_pkts = strtol(bufptr, NULL, 10); break; } } fclose(file); return dropped_pkts; } /* * With older kernels promiscuous mode is kind of interesting because we * have to reset the interface before exiting. The problem can't really * be solved without some daemon taking care of managing usage counts. * If we put the interface into promiscuous mode, we set a flag indicating * that we must take it out of that mode when the interface is closed, * and, when closing the interface, if that flag is set we take it out * of promiscuous mode. * * Even with newer kernels, we have the same issue with rfmon mode. */ static void pcap_cleanup_linux( pcap_t *handle ) { struct pcap_linux *handlep = handle->priv; struct ifreq ifr; #ifdef HAVE_LIBNL struct nl80211_state nlstate; int ret; #endif /* HAVE_LIBNL */ #ifdef IW_MODE_MONITOR int oldflags; struct iwreq ireq; #endif /* IW_MODE_MONITOR */ if (handlep->must_do_on_close != 0) { /* * There's something we have to do when closing this * pcap_t. */ if (handlep->must_do_on_close & MUST_CLEAR_PROMISC) { /* * We put the interface into promiscuous mode; * take it out of promiscuous mode. * * XXX - if somebody else wants it in promiscuous * mode, this code cannot know that, so it'll take * it out of promiscuous mode. That's not fixable * in 2.0[.x] kernels. */ memset(&ifr, 0, sizeof(ifr)); strlcpy(ifr.ifr_name, handlep->device, sizeof(ifr.ifr_name)); if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) { fprintf(stderr, "Can't restore interface %s flags (SIOCGIFFLAGS failed: %s).\n" "Please adjust manually.\n" "Hint: This can't happen with Linux >= 2.2.0.\n", handlep->device, strerror(errno)); } else { if (ifr.ifr_flags & IFF_PROMISC) { /* * Promiscuous mode is currently on; * turn it off. */ ifr.ifr_flags &= ~IFF_PROMISC; if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) { fprintf(stderr, "Can't restore interface %s flags (SIOCSIFFLAGS failed: %s).\n" "Please adjust manually.\n" "Hint: This can't happen with Linux >= 2.2.0.\n", handlep->device, strerror(errno)); } } } } #ifdef HAVE_LIBNL if (handlep->must_do_on_close & MUST_DELETE_MONIF) { ret = nl80211_init(handle, &nlstate, handlep->device); if (ret >= 0) { ret = del_mon_if(handle, handle->fd, &nlstate, handlep->device, handlep->mondevice); nl80211_cleanup(&nlstate); } if (ret < 0) { fprintf(stderr, "Can't delete monitor interface %s (%s).\n" "Please delete manually.\n", handlep->mondevice, handle->errbuf); } } #endif /* HAVE_LIBNL */ #ifdef IW_MODE_MONITOR if (handlep->must_do_on_close & MUST_CLEAR_RFMON) { /* * We put the interface into rfmon mode; * take it out of rfmon mode. * * XXX - if somebody else wants it in rfmon * mode, this code cannot know that, so it'll take * it out of rfmon mode. */ /* * First, take the interface down if it's up; * otherwise, we might get EBUSY. * If we get errors, just drive on and print * a warning if we can't restore the mode. */ oldflags = 0; memset(&ifr, 0, sizeof(ifr)); strlcpy(ifr.ifr_name, handlep->device, sizeof(ifr.ifr_name)); if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) != -1) { if (ifr.ifr_flags & IFF_UP) { oldflags = ifr.ifr_flags; ifr.ifr_flags &= ~IFF_UP; if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) oldflags = 0; /* didn't set, don't restore */ } } /* * Now restore the mode. */ strlcpy(ireq.ifr_ifrn.ifrn_name, handlep->device, sizeof ireq.ifr_ifrn.ifrn_name); ireq.u.mode = handlep->oldmode; if (ioctl(handle->fd, SIOCSIWMODE, &ireq) == -1) { /* * Scientist, you've failed. */ fprintf(stderr, "Can't restore interface %s wireless mode (SIOCSIWMODE failed: %s).\n" "Please adjust manually.\n", handlep->device, strerror(errno)); } /* * Now bring the interface back up if we brought * it down. */ if (oldflags != 0) { ifr.ifr_flags = oldflags; if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) { fprintf(stderr, "Can't bring interface %s back up (SIOCSIFFLAGS failed: %s).\n" "Please adjust manually.\n", handlep->device, strerror(errno)); } } } #endif /* IW_MODE_MONITOR */ /* * Take this pcap out of the list of pcaps for which we * have to take the interface out of some mode. */ pcap_remove_from_pcaps_to_close(handle); } if (handlep->mondevice != NULL) { free(handlep->mondevice); handlep->mondevice = NULL; } if (handlep->device != NULL) { free(handlep->device); handlep->device = NULL; } pcap_cleanup_live_common(handle); } /* * Get a handle for a live capture from the given device. You can * pass NULL as device to get all packages (without link level * information of course). If you pass 1 as promisc the interface * will be set to promiscous mode (XXX: I think this usage should * be deprecated and functions be added to select that later allow * modification of that values -- Torsten). */ static int pcap_activate_linux(pcap_t *handle) { struct pcap_linux *handlep = handle->priv; const char *device; struct ifreq ifr; int status = 0; int ret; device = handle->opt.source; /* * Make sure the name we were handed will fit into the ioctls we * might perform on the device; if not, return a "No such device" * indication, as the Linux kernel shouldn't support creating * a device whose name won't fit into those ioctls. * * "Will fit" means "will fit, complete with a null terminator", * so if the length, which does *not* include the null terminator, * is greater than *or equal to* the size of the field into which * we'll be copying it, that won't fit. */ if (strlen(device) >= sizeof(ifr.ifr_name)) { status = PCAP_ERROR_NO_SUCH_DEVICE; goto fail; } handle->inject_op = pcap_inject_linux; handle->setfilter_op = pcap_setfilter_linux; handle->setdirection_op = pcap_setdirection_linux; handle->set_datalink_op = pcap_set_datalink_linux; handle->getnonblock_op = pcap_getnonblock_fd; handle->setnonblock_op = pcap_setnonblock_fd; handle->cleanup_op = pcap_cleanup_linux; handle->read_op = pcap_read_linux; handle->stats_op = pcap_stats_linux; /* * The "any" device is a special device which causes us not * to bind to a particular device and thus to look at all * devices. */ if (strcmp(device, "any") == 0) { if (handle->opt.promisc) { handle->opt.promisc = 0; /* Just a warning. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Promiscuous mode not supported on the \"any\" device"); status = PCAP_WARNING_PROMISC_NOTSUP; } } handlep->device = strdup(device); if (handlep->device == NULL) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "strdup: %s", pcap_strerror(errno) ); return PCAP_ERROR; } /* copy timeout value */ handlep->timeout = handle->opt.timeout; /* * If we're in promiscuous mode, then we probably want * to see when the interface drops packets too, so get an * initial count from /proc/net/dev */ if (handle->opt.promisc) handlep->proc_dropped = linux_if_drops(handlep->device); /* * Current Linux kernels use the protocol family PF_PACKET to * allow direct access to all packets on the network while * older kernels had a special socket type SOCK_PACKET to * implement this feature. * While this old implementation is kind of obsolete we need * to be compatible with older kernels for a while so we are * trying both methods with the newer method preferred. */ ret = activate_new(handle); if (ret < 0) { /* * Fatal error with the new way; just fail. * ret has the error return; if it's PCAP_ERROR, * handle->errbuf has been set appropriately. */ status = ret; goto fail; } if (ret == 1) { /* * Success. * Try to use memory-mapped access. */ switch (activate_mmap(handle, &status)) { case 1: /* * We succeeded. status has been * set to the status to return, * which might be 0, or might be * a PCAP_WARNING_ value. */ return status; case 0: /* * Kernel doesn't support it - just continue * with non-memory-mapped access. */ break; case -1: /* * We failed to set up to use it, or the kernel * supports it, but we failed to enable it. * ret has been set to the error status to * return and, if it's PCAP_ERROR, handle->errbuf * contains the error message. */ status = ret; goto fail; } } else if (ret == 0) { /* Non-fatal error; try old way */ if ((ret = activate_old(handle)) != 1) { /* * Both methods to open the packet socket failed. * Tidy up and report our failure (handle->errbuf * is expected to be set by the functions above). */ status = ret; goto fail; } } /* * We set up the socket, but not with memory-mapped access. */ if (handle->opt.buffer_size != 0) { /* * Set the socket buffer size to the specified value. */ if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SO_RCVBUF: %s", pcap_strerror(errno)); status = PCAP_ERROR; goto fail; } } /* Allocate the buffer */ handle->buffer = malloc(handle->bufsize + handle->offset); if (!handle->buffer) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "malloc: %s", pcap_strerror(errno)); status = PCAP_ERROR; goto fail; } /* * "handle->fd" is a socket, so "select()" and "poll()" * should work on it. */ handle->selectable_fd = handle->fd; return status; fail: pcap_cleanup_linux(handle); return status; } /* * Read at most max_packets from the capture stream and call the callback * for each of them. Returns the number of packets handled or -1 if an * error occured. */ static int pcap_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) { /* * Currently, on Linux only one packet is delivered per read, * so we don't loop. */ return pcap_read_packet(handle, callback, user); } static int pcap_set_datalink_linux(pcap_t *handle, int dlt) { handle->linktype = dlt; return 0; } /* * linux_check_direction() * * Do checks based on packet direction. */ static inline int linux_check_direction(const pcap_t *handle, const struct sockaddr_ll *sll) { struct pcap_linux *handlep = handle->priv; if (sll->sll_pkttype == PACKET_OUTGOING) { /* * Outgoing packet. * If this is from the loopback device, reject it; * we'll see the packet as an incoming packet as well, * and we don't want to see it twice. */ if (sll->sll_ifindex == handlep->lo_ifindex) return 0; /* * If the user only wants incoming packets, reject it. */ if (handle->direction == PCAP_D_IN) return 0; } else { /* * Incoming packet. * If the user only wants outgoing packets, reject it. */ if (handle->direction == PCAP_D_OUT) return 0; } return 1; } /* * Read a packet from the socket calling the handler provided by * the user. Returns the number of packets received or -1 if an * error occured. */ static int pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata) { struct pcap_linux *handlep = handle->priv; u_char *bp; int offset; #ifdef HAVE_PF_PACKET_SOCKETS struct sockaddr_ll from; struct sll_header *hdrp; #else struct sockaddr from; #endif #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) struct iovec iov; struct msghdr msg; struct cmsghdr *cmsg; union { struct cmsghdr cmsg; char buf[CMSG_SPACE(sizeof(struct tpacket_auxdata))]; } cmsg_buf; #else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ socklen_t fromlen; #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ int packet_len, caplen; struct pcap_pkthdr pcap_header; struct bpf_aux_data aux_data; #ifdef HAVE_PF_PACKET_SOCKETS /* * If this is a cooked device, leave extra room for a * fake packet header. */ if (handlep->cooked) offset = SLL_HDR_LEN; else offset = 0; #else /* * This system doesn't have PF_PACKET sockets, so it doesn't * support cooked devices. */ offset = 0; #endif /* * Receive a single packet from the kernel. * We ignore EINTR, as that might just be due to a signal * being delivered - if the signal should interrupt the * loop, the signal handler should call pcap_breakloop() * to set handle->break_loop (we ignore it on other * platforms as well). * We also ignore ENETDOWN, so that we can continue to * capture traffic if the interface goes down and comes * back up again; comments in the kernel indicate that * we'll just block waiting for packets if we try to * receive from a socket that delivered ENETDOWN, and, * if we're using a memory-mapped buffer, we won't even * get notified of "network down" events. */ bp = handle->buffer + handle->offset; #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) msg.msg_name = &from; msg.msg_namelen = sizeof(from); msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_control = &cmsg_buf; msg.msg_controllen = sizeof(cmsg_buf); msg.msg_flags = 0; iov.iov_len = handle->bufsize - offset; iov.iov_base = bp + offset; #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ do { /* * Has "pcap_breakloop()" been called? */ if (handle->break_loop) { /* * Yes - clear the flag that indicates that it has, * and return PCAP_ERROR_BREAK as an indication that * we were told to break out of the loop. */ handle->break_loop = 0; return PCAP_ERROR_BREAK; } #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) packet_len = recvmsg(handle->fd, &msg, MSG_TRUNC); #else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ fromlen = sizeof(from); packet_len = recvfrom( handle->fd, bp + offset, handle->bufsize - offset, MSG_TRUNC, (struct sockaddr *) &from, &fromlen); #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ } while (packet_len == -1 && errno == EINTR); /* Check if an error occured */ if (packet_len == -1) { switch (errno) { case EAGAIN: return 0; /* no packet there */ case ENETDOWN: /* * The device on which we're capturing went away. * * XXX - we should really return * PCAP_ERROR_IFACE_NOT_UP, but pcap_dispatch() * etc. aren't defined to return that. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "The interface went down"); return PCAP_ERROR; default: snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "recvfrom: %s", pcap_strerror(errno)); return PCAP_ERROR; } } #ifdef HAVE_PF_PACKET_SOCKETS if (!handlep->sock_packet) { /* * Unfortunately, there is a window between socket() and * bind() where the kernel may queue packets from any * interface. If we're bound to a particular interface, * discard packets not from that interface. * * (If socket filters are supported, we could do the * same thing we do when changing the filter; however, * that won't handle packet sockets without socket * filter support, and it's a bit more complicated. * It would save some instructions per packet, however.) */ if (handlep->ifindex != -1 && from.sll_ifindex != handlep->ifindex) return 0; /* * Do checks based on packet direction. * We can only do this if we're using PF_PACKET; the * address returned for SOCK_PACKET is a "sockaddr_pkt" * which lacks the relevant packet type information. */ if (!linux_check_direction(handle, &from)) return 0; } #endif #ifdef HAVE_PF_PACKET_SOCKETS /* * If this is a cooked device, fill in the fake packet header. */ if (handlep->cooked) { /* * Add the length of the fake header to the length * of packet data we read. */ packet_len += SLL_HDR_LEN; hdrp = (struct sll_header *)bp; hdrp->sll_pkttype = map_packet_type_to_sll_type(from.sll_pkttype); hdrp->sll_hatype = htons(from.sll_hatype); hdrp->sll_halen = htons(from.sll_halen); memcpy(hdrp->sll_addr, from.sll_addr, (from.sll_halen > SLL_ADDRLEN) ? SLL_ADDRLEN : from.sll_halen); hdrp->sll_protocol = from.sll_protocol; } #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) if (handlep->vlan_offset != -1) { for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) { struct tpacket_auxdata *aux; unsigned int len; struct vlan_tag *tag; if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct tpacket_auxdata)) || cmsg->cmsg_level != SOL_PACKET || cmsg->cmsg_type != PACKET_AUXDATA) continue; aux = (struct tpacket_auxdata *)CMSG_DATA(cmsg); #if defined(TP_STATUS_VLAN_VALID) if ((aux->tp_vlan_tci == 0) && !(aux->tp_status & TP_STATUS_VLAN_VALID)) #else if (aux->tp_vlan_tci == 0) /* this is ambigious but without the TP_STATUS_VLAN_VALID flag, there is nothing that we can do */ #endif continue; len = packet_len > iov.iov_len ? iov.iov_len : packet_len; if (len < (unsigned int) handlep->vlan_offset) break; bp -= VLAN_TAG_LEN; memmove(bp, bp + VLAN_TAG_LEN, handlep->vlan_offset); tag = (struct vlan_tag *)(bp + handlep->vlan_offset); tag->vlan_tpid = htons(ETH_P_8021Q); tag->vlan_tci = htons(aux->tp_vlan_tci); /* store vlan tci to bpf_aux_data struct for userland bpf filter */ #if defined(TP_STATUS_VLAN_VALID) aux_data.vlan_tag = htons(aux->tp_vlan_tci) & 0x0fff; aux_data.vlan_tag_present = (aux->tp_status & TP_STATUS_VLAN_VALID); #endif packet_len += VLAN_TAG_LEN; } } #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */ #endif /* HAVE_PF_PACKET_SOCKETS */ /* * XXX: According to the kernel source we should get the real * packet len if calling recvfrom with MSG_TRUNC set. It does * not seem to work here :(, but it is supported by this code * anyway. * To be honest the code RELIES on that feature so this is really * broken with 2.2.x kernels. * I spend a day to figure out what's going on and I found out * that the following is happening: * * The packet comes from a random interface and the packet_rcv * hook is called with a clone of the packet. That code inserts * the packet into the receive queue of the packet socket. * If a filter is attached to that socket that filter is run * first - and there lies the problem. The default filter always * cuts the packet at the snaplen: * * # tcpdump -d * (000) ret #68 * * So the packet filter cuts down the packet. The recvfrom call * says "hey, it's only 68 bytes, it fits into the buffer" with * the result that we don't get the real packet length. This * is valid at least until kernel 2.2.17pre6. * * We currently handle this by making a copy of the filter * program, fixing all "ret" instructions with non-zero * operands to have an operand of MAXIMUM_SNAPLEN so that the * filter doesn't truncate the packet, and supplying that modified * filter to the kernel. */ caplen = packet_len; if (caplen > handle->snapshot) caplen = handle->snapshot; /* Run the packet filter if not using kernel filter */ if (handlep->filter_in_userland && handle->fcode.bf_insns) { if (bpf_filter_with_aux_data(handle->fcode.bf_insns, bp, packet_len, caplen, &aux_data) == 0) { /* rejected by filter */ return 0; } } /* Fill in our own header data */ /* get timestamp for this packet */ #if defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS) if (handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO) { if (ioctl(handle->fd, SIOCGSTAMPNS, &pcap_header.ts) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SIOCGSTAMPNS: %s", pcap_strerror(errno)); return PCAP_ERROR; } } else #endif { if (ioctl(handle->fd, SIOCGSTAMP, &pcap_header.ts) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SIOCGSTAMP: %s", pcap_strerror(errno)); return PCAP_ERROR; } } pcap_header.caplen = caplen; pcap_header.len = packet_len; /* * Count the packet. * * Arguably, we should count them before we check the filter, * as on many other platforms "ps_recv" counts packets * handed to the filter rather than packets that passed * the filter, but if filtering is done in the kernel, we * can't get a count of packets that passed the filter, * and that would mean the meaning of "ps_recv" wouldn't * be the same on all Linux systems. * * XXX - it's not the same on all systems in any case; * ideally, we should have a "get the statistics" call * that supplies more counts and indicates which of them * it supplies, so that we supply a count of packets * handed to the filter only on platforms where that * information is available. * * We count them here even if we can get the packet count * from the kernel, as we can only determine at run time * whether we'll be able to get it from the kernel (if * HAVE_TPACKET_STATS isn't defined, we can't get it from * the kernel, but if it is defined, the library might * have been built with a 2.4 or later kernel, but we * might be running on a 2.2[.x] kernel without Alexey * Kuznetzov's turbopacket patches, and thus the kernel * might not be able to supply those statistics). We * could, I guess, try, when opening the socket, to get * the statistics, and if we can not increment the count * here, but it's not clear that always incrementing * the count is more expensive than always testing a flag * in memory. * * We keep the count in "handlep->packets_read", and use that * for "ps_recv" if we can't get the statistics from the kernel. * We do that because, if we *can* get the statistics from * the kernel, we use "handlep->stat.ps_recv" and * "handlep->stat.ps_drop" as running counts, as reading the * statistics from the kernel resets the kernel statistics, * and if we directly increment "handlep->stat.ps_recv" here, * that means it will count packets *twice* on systems where * we can get kernel statistics - once here, and once in * pcap_stats_linux(). */ handlep->packets_read++; /* Call the user supplied callback function */ callback(userdata, &pcap_header, bp); return 1; } static int pcap_inject_linux(pcap_t *handle, const void *buf, size_t size) { struct pcap_linux *handlep = handle->priv; int ret; #ifdef HAVE_PF_PACKET_SOCKETS if (!handlep->sock_packet) { /* PF_PACKET socket */ if (handlep->ifindex == -1) { /* * We don't support sending on the "any" device. */ strlcpy(handle->errbuf, "Sending packets isn't supported on the \"any\" device", PCAP_ERRBUF_SIZE); return (-1); } if (handlep->cooked) { /* * We don't support sending on the "any" device. * * XXX - how do you send on a bound cooked-mode * socket? * Is a "sendto()" required there? */ strlcpy(handle->errbuf, "Sending packets isn't supported in cooked mode", PCAP_ERRBUF_SIZE); return (-1); } } #endif ret = send(handle->fd, buf, size, 0); if (ret == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "send: %s", pcap_strerror(errno)); return (-1); } return (ret); } /* * Get the statistics for the given packet capture handle. * Reports the number of dropped packets iff the kernel supports * the PACKET_STATISTICS "getsockopt()" argument (2.4 and later * kernels, and 2.2[.x] kernels with Alexey Kuznetzov's turbopacket * patches); otherwise, that information isn't available, and we lie * and report 0 as the count of dropped packets. */ static int pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats) { struct pcap_linux *handlep = handle->priv; #ifdef HAVE_TPACKET_STATS #ifdef HAVE_TPACKET3 /* * For sockets using TPACKET_V1 or TPACKET_V2, the extra * stuff at the end of a struct tpacket_stats_v3 will not * be filled in, and we don't look at it so this is OK even * for those sockets. In addition, the PF_PACKET socket * code in the kernel only uses the length parameter to * compute how much data to copy out and to indicate how * much data was copied out, so it's OK to base it on the * size of a struct tpacket_stats. * * XXX - it's probably OK, in fact, to just use a * struct tpacket_stats for V3 sockets, as we don't * care about the tp_freeze_q_cnt stat. */ struct tpacket_stats_v3 kstats; #else /* HAVE_TPACKET3 */ struct tpacket_stats kstats; #endif /* HAVE_TPACKET3 */ socklen_t len = sizeof (struct tpacket_stats); #endif /* HAVE_TPACKET_STATS */ long if_dropped = 0; /* * To fill in ps_ifdrop, we parse /proc/net/dev for the number */ if (handle->opt.promisc) { if_dropped = handlep->proc_dropped; handlep->proc_dropped = linux_if_drops(handlep->device); handlep->stat.ps_ifdrop += (handlep->proc_dropped - if_dropped); } #ifdef HAVE_TPACKET_STATS /* * Try to get the packet counts from the kernel. */ if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, &kstats, &len) > -1) { /* * On systems where the PACKET_STATISTICS "getsockopt()" * argument is supported on PF_PACKET sockets: * * "ps_recv" counts only packets that *passed* the * filter, not packets that didn't pass the filter. * This includes packets later dropped because we * ran out of buffer space. * * "ps_drop" counts packets dropped because we ran * out of buffer space. It doesn't count packets * dropped by the interface driver. It counts only * packets that passed the filter. * * See above for ps_ifdrop. * * Both statistics include packets not yet read from * the kernel by libpcap, and thus not yet seen by * the application. * * In "linux/net/packet/af_packet.c", at least in the * 2.4.9 kernel, "tp_packets" is incremented for every * packet that passes the packet filter *and* is * successfully queued on the socket; "tp_drops" is * incremented for every packet dropped because there's * not enough free space in the socket buffer. * * When the statistics are returned for a PACKET_STATISTICS * "getsockopt()" call, "tp_drops" is added to "tp_packets", * so that "tp_packets" counts all packets handed to * the PF_PACKET socket, including packets dropped because * there wasn't room on the socket buffer - but not * including packets that didn't pass the filter. * * In the BSD BPF, the count of received packets is * incremented for every packet handed to BPF, regardless * of whether it passed the filter. * * We can't make "pcap_stats()" work the same on both * platforms, but the best approximation is to return * "tp_packets" as the count of packets and "tp_drops" * as the count of drops. * * Keep a running total because each call to * getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, .... * resets the counters to zero. */ handlep->stat.ps_recv += kstats.tp_packets; handlep->stat.ps_drop += kstats.tp_drops; *stats = handlep->stat; return 0; } else { /* * If the error was EOPNOTSUPP, fall through, so that * if you build the library on a system with * "struct tpacket_stats" and run it on a system * that doesn't, it works as it does if the library * is built on a system without "struct tpacket_stats". */ if (errno != EOPNOTSUPP) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "pcap_stats: %s", pcap_strerror(errno)); return -1; } } #endif /* * On systems where the PACKET_STATISTICS "getsockopt()" argument * is not supported on PF_PACKET sockets: * * "ps_recv" counts only packets that *passed* the filter, * not packets that didn't pass the filter. It does not * count packets dropped because we ran out of buffer * space. * * "ps_drop" is not supported. * * "ps_ifdrop" is supported. It will return the number * of drops the interface reports in /proc/net/dev, * if that is available. * * "ps_recv" doesn't include packets not yet read from * the kernel by libpcap. * * We maintain the count of packets processed by libpcap in * "handlep->packets_read", for reasons described in the comment * at the end of pcap_read_packet(). We have no idea how many * packets were dropped by the kernel buffers -- but we know * how many the interface dropped, so we can return that. */ stats->ps_recv = handlep->packets_read; stats->ps_drop = 0; stats->ps_ifdrop = handlep->stat.ps_ifdrop; return 0; } static int add_linux_if(pcap_if_t **devlistp, const char *ifname, int fd, char *errbuf) { const char *p; char name[512]; /* XXX - pick a size */ char *q, *saveq; struct ifreq ifrflags; /* * Get the interface name. */ p = ifname; q = &name[0]; while (*p != '\0' && isascii(*p) && !isspace(*p)) { if (*p == ':') { /* * This could be the separator between a * name and an alias number, or it could be * the separator between a name with no * alias number and the next field. * * If there's a colon after digits, it * separates the name and the alias number, * otherwise it separates the name and the * next field. */ saveq = q; while (isascii(*p) && isdigit(*p)) *q++ = *p++; if (*p != ':') { /* * That was the next field, * not the alias number. */ q = saveq; } break; } else *q++ = *p++; } *q = '\0'; /* * Get the flags for this interface. */ strlcpy(ifrflags.ifr_name, name, sizeof(ifrflags.ifr_name)); if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) { if (errno == ENXIO || errno == ENODEV) return (0); /* device doesn't actually exist - ignore it */ (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "SIOCGIFFLAGS: %.*s: %s", (int)sizeof(ifrflags.ifr_name), ifrflags.ifr_name, pcap_strerror(errno)); return (-1); } /* * Add an entry for this interface, with no addresses. */ if (pcap_add_if(devlistp, name, ifrflags.ifr_flags, NULL, errbuf) == -1) { /* * Failure. */ return (-1); } return (0); } /* * Get from "/sys/class/net" all interfaces listed there; if they're * already in the list of interfaces we have, that won't add another * instance, but if they're not, that'll add them. * * We don't bother getting any addresses for them; it appears you can't * use SIOCGIFADDR on Linux to get IPv6 addresses for interfaces, and, * although some other types of addresses can be fetched with SIOCGIFADDR, * we don't bother with them for now. * * We also don't fail if we couldn't open "/sys/class/net"; we just leave * the list of interfaces as is, and return 0, so that we can try * scanning /proc/net/dev. * * Otherwise, we return 1 if we don't get an error and -1 if we do. */ static int scan_sys_class_net(pcap_if_t **devlistp, char *errbuf) { DIR *sys_class_net_d; int fd; struct dirent *ent; char subsystem_path[PATH_MAX+1]; struct stat statb; int ret = 1; sys_class_net_d = opendir("/sys/class/net"); if (sys_class_net_d == NULL) { /* * Don't fail if it doesn't exist at all. */ if (errno == ENOENT) return (0); /* * Fail if we got some other error. */ (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "Can't open /sys/class/net: %s", pcap_strerror(errno)); return (-1); } /* * Create a socket from which to fetch interface information. */ fd = socket(AF_INET, SOCK_DGRAM, 0); if (fd < 0) { (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "socket: %s", pcap_strerror(errno)); (void)closedir(sys_class_net_d); return (-1); } for (;;) { errno = 0; ent = readdir(sys_class_net_d); if (ent == NULL) { /* * Error or EOF; if errno != 0, it's an error. */ break; } /* * Ignore "." and "..". */ if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0) continue; /* * Ignore plain files; they do not have subdirectories * and thus have no attributes. */ if (ent->d_type == DT_REG) continue; /* * Is there an "ifindex" file under that name? * (We don't care whether it's a directory or * a symlink; older kernels have directories * for devices, newer kernels have symlinks to * directories.) */ snprintf(subsystem_path, sizeof subsystem_path, "/sys/class/net/%s/ifindex", ent->d_name); if (lstat(subsystem_path, &statb) != 0) { /* * Stat failed. Either there was an error * other than ENOENT, and we don't know if * this is an interface, or it's ENOENT, * and either some part of "/sys/class/net/{if}" * disappeared, in which case it probably means * the interface disappeared, or there's no * "ifindex" file, which means it's not a * network interface. */ continue; } /* * Attempt to add the interface. */ if (add_linux_if(devlistp, &ent->d_name[0], fd, errbuf) == -1) { /* Fail. */ ret = -1; break; } } if (ret != -1) { /* * Well, we didn't fail for any other reason; did we * fail due to an error reading the directory? */ if (errno != 0) { (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "Error reading /sys/class/net: %s", pcap_strerror(errno)); ret = -1; } } (void)close(fd); (void)closedir(sys_class_net_d); return (ret); } /* * Get from "/proc/net/dev" all interfaces listed there; if they're * already in the list of interfaces we have, that won't add another * instance, but if they're not, that'll add them. * * See comments from scan_sys_class_net(). */ static int scan_proc_net_dev(pcap_if_t **devlistp, char *errbuf) { FILE *proc_net_f; int fd; char linebuf[512]; int linenum; char *p; int ret = 0; proc_net_f = fopen("/proc/net/dev", "r"); if (proc_net_f == NULL) { /* * Don't fail if it doesn't exist at all. */ if (errno == ENOENT) return (0); /* * Fail if we got some other error. */ (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "Can't open /proc/net/dev: %s", pcap_strerror(errno)); return (-1); } /* * Create a socket from which to fetch interface information. */ fd = socket(AF_INET, SOCK_DGRAM, 0); if (fd < 0) { (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "socket: %s", pcap_strerror(errno)); (void)fclose(proc_net_f); return (-1); } for (linenum = 1; fgets(linebuf, sizeof linebuf, proc_net_f) != NULL; linenum++) { /* * Skip the first two lines - they're headers. */ if (linenum <= 2) continue; p = &linebuf[0]; /* * Skip leading white space. */ while (*p != '\0' && isascii(*p) && isspace(*p)) p++; if (*p == '\0' || *p == '\n') continue; /* blank line */ /* * Attempt to add the interface. */ if (add_linux_if(devlistp, p, fd, errbuf) == -1) { /* Fail. */ ret = -1; break; } } if (ret != -1) { /* * Well, we didn't fail for any other reason; did we * fail due to an error reading the file? */ if (ferror(proc_net_f)) { (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "Error reading /proc/net/dev: %s", pcap_strerror(errno)); ret = -1; } } (void)close(fd); (void)fclose(proc_net_f); return (ret); } /* * Description string for the "any" device. */ static const char any_descr[] = "Pseudo-device that captures on all interfaces"; int pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf) { int ret; /* * Read "/sys/class/net", and add to the list of interfaces all * interfaces listed there that we don't already have, because, * on Linux, SIOCGIFCONF reports only interfaces with IPv4 addresses, * and even getifaddrs() won't return information about * interfaces with no addresses, so you need to read "/sys/class/net" * to get the names of the rest of the interfaces. */ ret = scan_sys_class_net(alldevsp, errbuf); if (ret == -1) return (-1); /* failed */ if (ret == 0) { /* * No /sys/class/net; try reading /proc/net/dev instead. */ if (scan_proc_net_dev(alldevsp, errbuf) == -1) return (-1); } /* * Add the "any" device. */ if (pcap_add_if(alldevsp, "any", IFF_UP|IFF_RUNNING, any_descr, errbuf) < 0) return (-1); return (0); } /* * Attach the given BPF code to the packet capture device. */ static int pcap_setfilter_linux_common(pcap_t *handle, struct bpf_program *filter, int is_mmapped) { struct pcap_linux *handlep; #ifdef SO_ATTACH_FILTER struct sock_fprog fcode; int can_filter_in_kernel; int err = 0; #endif if (!handle) return -1; if (!filter) { strlcpy(handle->errbuf, "setfilter: No filter specified", PCAP_ERRBUF_SIZE); return -1; } handlep = handle->priv; /* Make our private copy of the filter */ if (install_bpf_program(handle, filter) < 0) /* install_bpf_program() filled in errbuf */ return -1; /* * Run user level packet filter by default. Will be overriden if * installing a kernel filter succeeds. */ handlep->filter_in_userland = 1; /* Install kernel level filter if possible */ #ifdef SO_ATTACH_FILTER #ifdef USHRT_MAX if (handle->fcode.bf_len > USHRT_MAX) { /* * fcode.len is an unsigned short for current kernel. * I have yet to see BPF-Code with that much * instructions but still it is possible. So for the * sake of correctness I added this check. */ fprintf(stderr, "Warning: Filter too complex for kernel\n"); fcode.len = 0; fcode.filter = NULL; can_filter_in_kernel = 0; } else #endif /* USHRT_MAX */ { /* * Oh joy, the Linux kernel uses struct sock_fprog instead * of struct bpf_program and of course the length field is * of different size. Pointed out by Sebastian * * Oh, and we also need to fix it up so that all "ret" * instructions with non-zero operands have MAXIMUM_SNAPLEN * as the operand if we're not capturing in memory-mapped * mode, and so that, if we're in cooked mode, all memory- * reference instructions use special magic offsets in * references to the link-layer header and assume that the * link-layer payload begins at 0; "fix_program()" will do * that. */ switch (fix_program(handle, &fcode, is_mmapped)) { case -1: default: /* * Fatal error; just quit. * (The "default" case shouldn't happen; we * return -1 for that reason.) */ return -1; case 0: /* * The program performed checks that we can't make * work in the kernel. */ can_filter_in_kernel = 0; break; case 1: /* * We have a filter that'll work in the kernel. */ can_filter_in_kernel = 1; break; } } /* * NOTE: at this point, we've set both the "len" and "filter" * fields of "fcode". As of the 2.6.32.4 kernel, at least, * those are the only members of the "sock_fprog" structure, * so we initialize every member of that structure. * * If there is anything in "fcode" that is not initialized, * it is either a field added in a later kernel, or it's * padding. * * If a new field is added, this code needs to be updated * to set it correctly. * * If there are no other fields, then: * * if the Linux kernel looks at the padding, it's * buggy; * * if the Linux kernel doesn't look at the padding, * then if some tool complains that we're passing * uninitialized data to the kernel, then the tool * is buggy and needs to understand that it's just * padding. */ if (can_filter_in_kernel) { if ((err = set_kernel_filter(handle, &fcode)) == 0) { /* * Installation succeded - using kernel filter, * so userland filtering not needed. */ handlep->filter_in_userland = 0; } else if (err == -1) /* Non-fatal error */ { /* * Print a warning if we weren't able to install * the filter for a reason other than "this kernel * isn't configured to support socket filters. */ if (errno != ENOPROTOOPT && errno != EOPNOTSUPP) { fprintf(stderr, "Warning: Kernel filter failed: %s\n", pcap_strerror(errno)); } } } /* * If we're not using the kernel filter, get rid of any kernel * filter that might've been there before, e.g. because the * previous filter could work in the kernel, or because some other * code attached a filter to the socket by some means other than * calling "pcap_setfilter()". Otherwise, the kernel filter may * filter out packets that would pass the new userland filter. */ if (handlep->filter_in_userland) { if (reset_kernel_filter(handle) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't remove kernel filter: %s", pcap_strerror(errno)); err = -2; /* fatal error */ } } /* * Free up the copy of the filter that was made by "fix_program()". */ if (fcode.filter != NULL) free(fcode.filter); if (err == -2) /* Fatal error */ return -1; #endif /* SO_ATTACH_FILTER */ return 0; } static int pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter) { return pcap_setfilter_linux_common(handle, filter, 0); } /* * Set direction flag: Which packets do we accept on a forwarding * single device? IN, OUT or both? */ static int pcap_setdirection_linux(pcap_t *handle, pcap_direction_t d) { #ifdef HAVE_PF_PACKET_SOCKETS struct pcap_linux *handlep = handle->priv; if (!handlep->sock_packet) { handle->direction = d; return 0; } #endif /* * We're not using PF_PACKET sockets, so we can't determine * the direction of the packet. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Setting direction is not supported on SOCK_PACKET sockets"); return -1; } #ifdef HAVE_PF_PACKET_SOCKETS /* * Map the PACKET_ value to a LINUX_SLL_ value; we * want the same numerical value to be used in * the link-layer header even if the numerical values * for the PACKET_ #defines change, so that programs * that look at the packet type field will always be * able to handle DLT_LINUX_SLL captures. */ static short int map_packet_type_to_sll_type(short int sll_pkttype) { switch (sll_pkttype) { case PACKET_HOST: return htons(LINUX_SLL_HOST); case PACKET_BROADCAST: return htons(LINUX_SLL_BROADCAST); case PACKET_MULTICAST: return htons(LINUX_SLL_MULTICAST); case PACKET_OTHERHOST: return htons(LINUX_SLL_OTHERHOST); case PACKET_OUTGOING: return htons(LINUX_SLL_OUTGOING); default: return -1; } } #endif /* * Linux uses the ARP hardware type to identify the type of an * interface. pcap uses the DLT_xxx constants for this. This * function takes a pointer to a "pcap_t", and an ARPHRD_xxx * constant, as arguments, and sets "handle->linktype" to the * appropriate DLT_XXX constant and sets "handle->offset" to * the appropriate value (to make "handle->offset" plus link-layer * header length be a multiple of 4, so that the link-layer payload * will be aligned on a 4-byte boundary when capturing packets). * (If the offset isn't set here, it'll be 0; add code as appropriate * for cases where it shouldn't be 0.) * * If "cooked_ok" is non-zero, we can use DLT_LINUX_SLL and capture * in cooked mode; otherwise, we can't use cooked mode, so we have * to pick some type that works in raw mode, or fail. * * Sets the link type to -1 if unable to map the type. */ static void map_arphrd_to_dlt(pcap_t *handle, int arptype, const char *device, int cooked_ok) { static const char cdma_rmnet[] = "cdma_rmnet"; switch (arptype) { case ARPHRD_ETHER: /* * For various annoying reasons having to do with DHCP * software, some versions of Android give the mobile- * phone-network interface an ARPHRD_ value of * ARPHRD_ETHER, even though the packet supplied by * that interface have no link-layer header, and begin * with an IP header, so that the ARPHRD_ value should * be ARPHRD_NONE. * * Detect those devices by checking the device name, and * use DLT_RAW for them. */ if (strncmp(device, cdma_rmnet, sizeof cdma_rmnet - 1) == 0) { handle->linktype = DLT_RAW; return; } /* * This is (presumably) a real Ethernet capture; give it a * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so * that an application can let you choose it, in case you're * capturing DOCSIS traffic that a Cisco Cable Modem * Termination System is putting out onto an Ethernet (it * doesn't put an Ethernet header onto the wire, it puts raw * DOCSIS frames out on the wire inside the low-level * Ethernet framing). * * XXX - are there any sorts of "fake Ethernet" that have * ARPHRD_ETHER but that *shouldn't offer DLT_DOCSIS as * a Cisco CMTS won't put traffic onto it or get traffic * bridged onto it? ISDN is handled in "activate_new()", * as we fall back on cooked mode there; are there any * others? */ handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); /* * If that fails, just leave the list empty. */ if (handle->dlt_list != NULL) { handle->dlt_list[0] = DLT_EN10MB; handle->dlt_list[1] = DLT_DOCSIS; handle->dlt_count = 2; } /* FALLTHROUGH */ case ARPHRD_METRICOM: case ARPHRD_LOOPBACK: handle->linktype = DLT_EN10MB; handle->offset = 2; break; case ARPHRD_EETHER: handle->linktype = DLT_EN3MB; break; case ARPHRD_AX25: handle->linktype = DLT_AX25_KISS; break; case ARPHRD_PRONET: handle->linktype = DLT_PRONET; break; case ARPHRD_CHAOS: handle->linktype = DLT_CHAOS; break; #ifndef ARPHRD_CAN #define ARPHRD_CAN 280 #endif case ARPHRD_CAN: handle->linktype = DLT_CAN_SOCKETCAN; break; #ifndef ARPHRD_IEEE802_TR #define ARPHRD_IEEE802_TR 800 /* From Linux 2.4 */ #endif case ARPHRD_IEEE802_TR: case ARPHRD_IEEE802: handle->linktype = DLT_IEEE802; handle->offset = 2; break; case ARPHRD_ARCNET: handle->linktype = DLT_ARCNET_LINUX; break; #ifndef ARPHRD_FDDI /* From Linux 2.2.13 */ #define ARPHRD_FDDI 774 #endif case ARPHRD_FDDI: handle->linktype = DLT_FDDI; handle->offset = 3; break; #ifndef ARPHRD_ATM /* FIXME: How to #include this? */ #define ARPHRD_ATM 19 #endif case ARPHRD_ATM: /* * The Classical IP implementation in ATM for Linux * supports both what RFC 1483 calls "LLC Encapsulation", * in which each packet has an LLC header, possibly * with a SNAP header as well, prepended to it, and * what RFC 1483 calls "VC Based Multiplexing", in which * different virtual circuits carry different network * layer protocols, and no header is prepended to packets. * * They both have an ARPHRD_ type of ARPHRD_ATM, so * you can't use the ARPHRD_ type to find out whether * captured packets will have an LLC header, and, * while there's a socket ioctl to *set* the encapsulation * type, there's no ioctl to *get* the encapsulation type. * * This means that * * programs that dissect Linux Classical IP frames * would have to check for an LLC header and, * depending on whether they see one or not, dissect * the frame as LLC-encapsulated or as raw IP (I * don't know whether there's any traffic other than * IP that would show up on the socket, or whether * there's any support for IPv6 in the Linux * Classical IP code); * * filter expressions would have to compile into * code that checks for an LLC header and does * the right thing. * * Both of those are a nuisance - and, at least on systems * that support PF_PACKET sockets, we don't have to put * up with those nuisances; instead, we can just capture * in cooked mode. That's what we'll do, if we can. * Otherwise, we'll just fail. */ if (cooked_ok) handle->linktype = DLT_LINUX_SLL; else handle->linktype = -1; break; #ifndef ARPHRD_IEEE80211 /* From Linux 2.4.6 */ #define ARPHRD_IEEE80211 801 #endif case ARPHRD_IEEE80211: handle->linktype = DLT_IEEE802_11; break; #ifndef ARPHRD_IEEE80211_PRISM /* From Linux 2.4.18 */ #define ARPHRD_IEEE80211_PRISM 802 #endif case ARPHRD_IEEE80211_PRISM: handle->linktype = DLT_PRISM_HEADER; break; #ifndef ARPHRD_IEEE80211_RADIOTAP /* new */ #define ARPHRD_IEEE80211_RADIOTAP 803 #endif case ARPHRD_IEEE80211_RADIOTAP: handle->linktype = DLT_IEEE802_11_RADIO; break; case ARPHRD_PPP: /* * Some PPP code in the kernel supplies no link-layer * header whatsoever to PF_PACKET sockets; other PPP * code supplies PPP link-layer headers ("syncppp.c"); * some PPP code might supply random link-layer * headers (PPP over ISDN - there's code in Ethereal, * for example, to cope with PPP-over-ISDN captures * with which the Ethereal developers have had to cope, * heuristically trying to determine which of the * oddball link-layer headers particular packets have). * * As such, we just punt, and run all PPP interfaces * in cooked mode, if we can; otherwise, we just treat * it as DLT_RAW, for now - if somebody needs to capture, * on a 2.0[.x] kernel, on PPP devices that supply a * link-layer header, they'll have to add code here to * map to the appropriate DLT_ type (possibly adding a * new DLT_ type, if necessary). */ if (cooked_ok) handle->linktype = DLT_LINUX_SLL; else { /* * XXX - handle ISDN types here? We can't fall * back on cooked sockets, so we'd have to * figure out from the device name what type of * link-layer encapsulation it's using, and map * that to an appropriate DLT_ value, meaning * we'd map "isdnN" devices to DLT_RAW (they * supply raw IP packets with no link-layer * header) and "isdY" devices to a new DLT_I4L_IP * type that has only an Ethernet packet type as * a link-layer header. * * But sometimes we seem to get random crap * in the link-layer header when capturing on * ISDN devices.... */ handle->linktype = DLT_RAW; } break; #ifndef ARPHRD_CISCO #define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */ #endif case ARPHRD_CISCO: handle->linktype = DLT_C_HDLC; break; /* Not sure if this is correct for all tunnels, but it * works for CIPE */ case ARPHRD_TUNNEL: #ifndef ARPHRD_SIT #define ARPHRD_SIT 776 /* From Linux 2.2.13 */ #endif case ARPHRD_SIT: case ARPHRD_CSLIP: case ARPHRD_SLIP6: case ARPHRD_CSLIP6: case ARPHRD_ADAPT: case ARPHRD_SLIP: #ifndef ARPHRD_RAWHDLC #define ARPHRD_RAWHDLC 518 #endif case ARPHRD_RAWHDLC: #ifndef ARPHRD_DLCI #define ARPHRD_DLCI 15 #endif case ARPHRD_DLCI: /* * XXX - should some of those be mapped to DLT_LINUX_SLL * instead? Should we just map all of them to DLT_LINUX_SLL? */ handle->linktype = DLT_RAW; break; #ifndef ARPHRD_FRAD #define ARPHRD_FRAD 770 #endif case ARPHRD_FRAD: handle->linktype = DLT_FRELAY; break; case ARPHRD_LOCALTLK: handle->linktype = DLT_LTALK; break; case 18: /* * RFC 4338 defines an encapsulation for IP and ARP * packets that's compatible with the RFC 2625 * encapsulation, but that uses a different ARP * hardware type and hardware addresses. That * ARP hardware type is 18; Linux doesn't define * any ARPHRD_ value as 18, but if it ever officially * supports RFC 4338-style IP-over-FC, it should define * one. * * For now, we map it to DLT_IP_OVER_FC, in the hopes * that this will encourage its use in the future, * should Linux ever officially support RFC 4338-style * IP-over-FC. */ handle->linktype = DLT_IP_OVER_FC; break; #ifndef ARPHRD_FCPP #define ARPHRD_FCPP 784 #endif case ARPHRD_FCPP: #ifndef ARPHRD_FCAL #define ARPHRD_FCAL 785 #endif case ARPHRD_FCAL: #ifndef ARPHRD_FCPL #define ARPHRD_FCPL 786 #endif case ARPHRD_FCPL: #ifndef ARPHRD_FCFABRIC #define ARPHRD_FCFABRIC 787 #endif case ARPHRD_FCFABRIC: /* * Back in 2002, Donald Lee at Cray wanted a DLT_ for * IP-over-FC: * * http://www.mail-archive.com/tcpdump-workers@sandelman.ottawa.on.ca/msg01043.html * * and one was assigned. * * In a later private discussion (spun off from a message * on the ethereal-users list) on how to get that DLT_ * value in libpcap on Linux, I ended up deciding that * the best thing to do would be to have him tweak the * driver to set the ARPHRD_ value to some ARPHRD_FCxx * type, and map all those types to DLT_IP_OVER_FC: * * I've checked into the libpcap and tcpdump CVS tree * support for DLT_IP_OVER_FC. In order to use that, * you'd have to modify your modified driver to return * one of the ARPHRD_FCxxx types, in "fcLINUXfcp.c" - * change it to set "dev->type" to ARPHRD_FCFABRIC, for * example (the exact value doesn't matter, it can be * any of ARPHRD_FCPP, ARPHRD_FCAL, ARPHRD_FCPL, or * ARPHRD_FCFABRIC). * * 11 years later, Christian Svensson wanted to map * various ARPHRD_ values to DLT_FC_2 and * DLT_FC_2_WITH_FRAME_DELIMS for raw Fibre Channel * frames: * * https://github.com/mcr/libpcap/pull/29 * * There doesn't seem to be any network drivers that uses * any of the ARPHRD_FC* values for IP-over-FC, and * it's not exactly clear what the "Dummy types for non * ARP hardware" are supposed to mean (link-layer * header type? Physical network type?), so it's * not exactly clear why the ARPHRD_FC* types exist * in the first place. * * For now, we map them to DLT_FC_2, and provide an * option of DLT_FC_2_WITH_FRAME_DELIMS, as well as * DLT_IP_OVER_FC just in case there's some old * driver out there that uses one of those types for * IP-over-FC on which somebody wants to capture * packets. */ handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); /* * If that fails, just leave the list empty. */ if (handle->dlt_list != NULL) { handle->dlt_list[0] = DLT_FC_2; handle->dlt_list[1] = DLT_FC_2_WITH_FRAME_DELIMS; handle->dlt_list[2] = DLT_IP_OVER_FC; handle->dlt_count = 3; } handle->linktype = DLT_FC_2; break; #ifndef ARPHRD_IRDA #define ARPHRD_IRDA 783 #endif case ARPHRD_IRDA: /* Don't expect IP packet out of this interfaces... */ handle->linktype = DLT_LINUX_IRDA; /* We need to save packet direction for IrDA decoding, * so let's use "Linux-cooked" mode. Jean II * * XXX - this is handled in activate_new(). */ //handlep->cooked = 1; break; /* ARPHRD_LAPD is unofficial and randomly allocated, if reallocation * is needed, please report it to <daniele@orlandi.com> */ #ifndef ARPHRD_LAPD #define ARPHRD_LAPD 8445 #endif case ARPHRD_LAPD: /* Don't expect IP packet out of this interfaces... */ handle->linktype = DLT_LINUX_LAPD; break; #ifndef ARPHRD_NONE #define ARPHRD_NONE 0xFFFE #endif case ARPHRD_NONE: /* * No link-layer header; packets are just IP * packets, so use DLT_RAW. */ handle->linktype = DLT_RAW; break; #ifndef ARPHRD_IEEE802154 #define ARPHRD_IEEE802154 804 #endif case ARPHRD_IEEE802154: handle->linktype = DLT_IEEE802_15_4_NOFCS; break; #ifndef ARPHRD_NETLINK #define ARPHRD_NETLINK 824 #endif case ARPHRD_NETLINK: handle->linktype = DLT_NETLINK; /* * We need to use cooked mode, so that in sll_protocol we * pick up the netlink protocol type such as NETLINK_ROUTE, * NETLINK_GENERIC, NETLINK_FIB_LOOKUP, etc. * * XXX - this is handled in activate_new(). */ //handlep->cooked = 1; break; default: handle->linktype = -1; break; } } /* ===== Functions to interface to the newer kernels ================== */ /* * Try to open a packet socket using the new kernel PF_PACKET interface. * Returns 1 on success, 0 on an error that means the new interface isn't * present (so the old SOCK_PACKET interface should be tried), and a * PCAP_ERROR_ value on an error that means that the old mechanism won't * work either (so it shouldn't be tried). */ static int activate_new(pcap_t *handle) { #ifdef HAVE_PF_PACKET_SOCKETS struct pcap_linux *handlep = handle->priv; const char *device = handle->opt.source; int is_any_device = (strcmp(device, "any") == 0); int sock_fd = -1, arptype; #ifdef HAVE_PACKET_AUXDATA int val; #endif int err = 0; struct packet_mreq mr; #ifdef SO_BPF_EXTENSIONS int bpf_extensions; socklen_t len; #endif /* * Open a socket with protocol family packet. If the * "any" device was specified, we open a SOCK_DGRAM * socket for the cooked interface, otherwise we first * try a SOCK_RAW socket for the raw interface. */ sock_fd = is_any_device ? socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL)) : socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); if (sock_fd == -1) { if (errno == EINVAL || errno == EAFNOSUPPORT) { /* * We don't support PF_PACKET/SOCK_whatever * sockets; try the old mechanism. */ return 0; } snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "socket: %s", pcap_strerror(errno) ); if (errno == EPERM || errno == EACCES) { /* * You don't have permission to open the * socket. */ return PCAP_ERROR_PERM_DENIED; } else { /* * Other error. */ return PCAP_ERROR; } } /* It seems the kernel supports the new interface. */ handlep->sock_packet = 0; /* * Get the interface index of the loopback device. * If the attempt fails, don't fail, just set the * "handlep->lo_ifindex" to -1. * * XXX - can there be more than one device that loops * packets back, i.e. devices other than "lo"? If so, * we'd need to find them all, and have an array of * indices for them, and check all of them in * "pcap_read_packet()". */ handlep->lo_ifindex = iface_get_id(sock_fd, "lo", handle->errbuf); /* * Default value for offset to align link-layer payload * on a 4-byte boundary. */ handle->offset = 0; /* * What kind of frames do we have to deal with? Fall back * to cooked mode if we have an unknown interface type * or a type we know doesn't work well in raw mode. */ if (!is_any_device) { /* Assume for now we don't need cooked mode. */ handlep->cooked = 0; if (handle->opt.rfmon) { /* * We were asked to turn on monitor mode. * Do so before we get the link-layer type, * because entering monitor mode could change * the link-layer type. */ err = enter_rfmon_mode(handle, sock_fd, device); if (err < 0) { /* Hard failure */ close(sock_fd); return err; } if (err == 0) { /* * Nothing worked for turning monitor mode * on. */ close(sock_fd); return PCAP_ERROR_RFMON_NOTSUP; } /* * Either monitor mode has been turned on for * the device, or we've been given a different * device to open for monitor mode. If we've * been given a different device, use it. */ if (handlep->mondevice != NULL) device = handlep->mondevice; } arptype = iface_get_arptype(sock_fd, device, handle->errbuf); if (arptype < 0) { close(sock_fd); return arptype; } map_arphrd_to_dlt(handle, arptype, device, 1); if (handle->linktype == -1 || handle->linktype == DLT_LINUX_SLL || handle->linktype == DLT_LINUX_IRDA || handle->linktype == DLT_LINUX_LAPD || handle->linktype == DLT_NETLINK || (handle->linktype == DLT_EN10MB && (strncmp("isdn", device, 4) == 0 || strncmp("isdY", device, 4) == 0))) { /* * Unknown interface type (-1), or a * device we explicitly chose to run * in cooked mode (e.g., PPP devices), * or an ISDN device (whose link-layer * type we can only determine by using * APIs that may be different on different * kernels) - reopen in cooked mode. */ if (close(sock_fd) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "close: %s", pcap_strerror(errno)); return PCAP_ERROR; } sock_fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL)); if (sock_fd == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "socket: %s", pcap_strerror(errno)); if (errno == EPERM || errno == EACCES) { /* * You don't have permission to * open the socket. */ return PCAP_ERROR_PERM_DENIED; } else { /* * Other error. */ return PCAP_ERROR; } } handlep->cooked = 1; /* * Get rid of any link-layer type list * we allocated - this only supports cooked * capture. */ if (handle->dlt_list != NULL) { free(handle->dlt_list); handle->dlt_list = NULL; handle->dlt_count = 0; } if (handle->linktype == -1) { /* * Warn that we're falling back on * cooked mode; we may want to * update "map_arphrd_to_dlt()" * to handle the new type. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "arptype %d not " "supported by libpcap - " "falling back to cooked " "socket", arptype); } /* * IrDA capture is not a real "cooked" capture, * it's IrLAP frames, not IP packets. The * same applies to LAPD capture. */ if (handle->linktype != DLT_LINUX_IRDA && handle->linktype != DLT_LINUX_LAPD && handle->linktype != DLT_NETLINK) handle->linktype = DLT_LINUX_SLL; } handlep->ifindex = iface_get_id(sock_fd, device, handle->errbuf); if (handlep->ifindex == -1) { close(sock_fd); return PCAP_ERROR; } if ((err = iface_bind(sock_fd, handlep->ifindex, handle->errbuf)) != 1) { close(sock_fd); if (err < 0) return err; else return 0; /* try old mechanism */ } } else { /* * The "any" device. */ if (handle->opt.rfmon) { /* * It doesn't support monitor mode. */ close(sock_fd); return PCAP_ERROR_RFMON_NOTSUP; } /* * It uses cooked mode. */ handlep->cooked = 1; handle->linktype = DLT_LINUX_SLL; /* * We're not bound to a device. * For now, we're using this as an indication * that we can't transmit; stop doing that only * if we figure out how to transmit in cooked * mode. */ handlep->ifindex = -1; } /* * Select promiscuous mode on if "promisc" is set. * * Do not turn allmulti mode on if we don't select * promiscuous mode - on some devices (e.g., Orinoco * wireless interfaces), allmulti mode isn't supported * and the driver implements it by turning promiscuous * mode on, and that screws up the operation of the * card as a normal networking interface, and on no * other platform I know of does starting a non- * promiscuous capture affect which multicast packets * are received by the interface. */ /* * Hmm, how can we set promiscuous mode on all interfaces? * I am not sure if that is possible at all. For now, we * silently ignore attempts to turn promiscuous mode on * for the "any" device (so you don't have to explicitly * disable it in programs such as tcpdump). */ if (!is_any_device && handle->opt.promisc) { memset(&mr, 0, sizeof(mr)); mr.mr_ifindex = handlep->ifindex; mr.mr_type = PACKET_MR_PROMISC; if (setsockopt(sock_fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mr, sizeof(mr)) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "setsockopt: %s", pcap_strerror(errno)); close(sock_fd); return PCAP_ERROR; } } /* Enable auxillary data if supported and reserve room for * reconstructing VLAN headers. */ #ifdef HAVE_PACKET_AUXDATA val = 1; if (setsockopt(sock_fd, SOL_PACKET, PACKET_AUXDATA, &val, sizeof(val)) == -1 && errno != ENOPROTOOPT) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "setsockopt: %s", pcap_strerror(errno)); close(sock_fd); return PCAP_ERROR; } handle->offset += VLAN_TAG_LEN; #endif /* HAVE_PACKET_AUXDATA */ /* * This is a 2.2[.x] or later kernel (we know that * because we're not using a SOCK_PACKET socket - * PF_PACKET is supported only in 2.2 and later * kernels). * * We can safely pass "recvfrom()" a byte count * based on the snapshot length. * * If we're in cooked mode, make the snapshot length * large enough to hold a "cooked mode" header plus * 1 byte of packet data (so we don't pass a byte * count of 0 to "recvfrom()"). */ if (handlep->cooked) { if (handle->snapshot < SLL_HDR_LEN + 1) handle->snapshot = SLL_HDR_LEN + 1; } handle->bufsize = handle->snapshot; /* * Set the offset at which to insert VLAN tags. */ switch (handle->linktype) { case DLT_EN10MB: handlep->vlan_offset = 2 * ETH_ALEN; break; case DLT_LINUX_SLL: handlep->vlan_offset = 14; break; default: handlep->vlan_offset = -1; /* unknown */ break; } #if defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS) if (handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO) { int nsec_tstamps = 1; if (setsockopt(sock_fd, SOL_SOCKET, SO_TIMESTAMPNS, &nsec_tstamps, sizeof(nsec_tstamps)) < 0) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "setsockopt: unable to set SO_TIMESTAMPNS"); close(sock_fd); return PCAP_ERROR; } } #endif /* defined(SIOCGSTAMPNS) && defined(SO_TIMESTAMPNS) */ /* * We've succeeded. Save the socket FD in the pcap structure. */ handle->fd = sock_fd; #ifdef SO_BPF_EXTENSIONS /* * Can we generate special code for VLAN checks? * (XXX - what if we need the special code but it's not supported * by the OS? Is that possible?) */ if (getsockopt(sock_fd, SOL_SOCKET, SO_BPF_EXTENSIONS, &bpf_extensions, &len) == 0) { if (bpf_extensions >= SKF_AD_VLAN_TAG_PRESENT) { /* * Yes, we can. Request that we do so. */ handle->bpf_codegen_flags |= BPF_SPECIAL_VLAN_HANDLING; } } #endif /* SO_BPF_EXTENSIONS */ return 1; #else /* HAVE_PF_PACKET_SOCKETS */ strlcpy(ebuf, "New packet capturing interface not supported by build " "environment", PCAP_ERRBUF_SIZE); return 0; #endif /* HAVE_PF_PACKET_SOCKETS */ } #ifdef HAVE_PACKET_RING /* * Attempt to activate with memory-mapped access. * * On success, returns 1, and sets *status to 0 if there are no warnings * or to a PCAP_WARNING_ code if there is a warning. * * On failure due to lack of support for memory-mapped capture, returns * 0. * * On error, returns -1, and sets *status to the appropriate error code; * if that is PCAP_ERROR, sets handle->errbuf to the appropriate message. */ static int activate_mmap(pcap_t *handle, int *status) { struct pcap_linux *handlep = handle->priv; int ret; /* * Attempt to allocate a buffer to hold the contents of one * packet, for use by the oneshot callback. */ handlep->oneshot_buffer = malloc(handle->snapshot); if (handlep->oneshot_buffer == NULL) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't allocate oneshot buffer: %s", pcap_strerror(errno)); *status = PCAP_ERROR; return -1; } if (handle->opt.buffer_size == 0) { /* by default request 2M for the ring buffer */ handle->opt.buffer_size = 2*1024*1024; } ret = prepare_tpacket_socket(handle); if (ret == -1) { free(handlep->oneshot_buffer); *status = PCAP_ERROR; return ret; } ret = create_ring(handle, status); if (ret == 0) { /* * We don't support memory-mapped capture; our caller * will fall back on reading from the socket. */ free(handlep->oneshot_buffer); return 0; } if (ret == -1) { /* * Error attempting to enable memory-mapped capture; * fail. create_ring() has set *status. */ free(handlep->oneshot_buffer); return -1; } /* * Success. *status has been set either to 0 if there are no * warnings or to a PCAP_WARNING_ value if there is a warning. * * Override some defaults and inherit the other fields from * activate_new. * handle->offset is used to get the current position into the rx ring. * handle->cc is used to store the ring size. */ switch (handlep->tp_version) { case TPACKET_V1: handle->read_op = pcap_read_linux_mmap_v1; break; #ifdef HAVE_TPACKET2 case TPACKET_V2: handle->read_op = pcap_read_linux_mmap_v2; break; #endif #ifdef HAVE_TPACKET3 case TPACKET_V3: handle->read_op = pcap_read_linux_mmap_v3; break; #endif } handle->cleanup_op = pcap_cleanup_linux_mmap; handle->setfilter_op = pcap_setfilter_linux_mmap; handle->setnonblock_op = pcap_setnonblock_mmap; handle->getnonblock_op = pcap_getnonblock_mmap; handle->oneshot_callback = pcap_oneshot_mmap; handle->selectable_fd = handle->fd; return 1; } #else /* HAVE_PACKET_RING */ static int activate_mmap(pcap_t *handle _U_, int *status _U_) { return 0; } #endif /* HAVE_PACKET_RING */ #ifdef HAVE_PACKET_RING #if defined(HAVE_TPACKET2) || defined(HAVE_TPACKET3) /* * Attempt to set the socket to the specified version of the memory-mapped * header. * * Return 0 if we succeed; return 1 if we fail because that version isn't * supported; return -1 on any other error, and set handle->errbuf. */ static int init_tpacket(pcap_t *handle, int version, const char *version_str) { struct pcap_linux *handlep = handle->priv; int val = version; socklen_t len = sizeof(val); /* Probe whether kernel supports the specified TPACKET version */ if (getsockopt(handle->fd, SOL_PACKET, PACKET_HDRLEN, &val, &len) < 0) { if (errno == ENOPROTOOPT || errno == EINVAL) return 1; /* no */ /* Failed to even find out; this is a fatal error. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't get %s header len on packet socket: %s", version_str, pcap_strerror(errno)); return -1; } handlep->tp_hdrlen = val; val = version; if (setsockopt(handle->fd, SOL_PACKET, PACKET_VERSION, &val, sizeof(val)) < 0) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't activate %s on packet socket: %s", version_str, pcap_strerror(errno)); return -1; } handlep->tp_version = version; /* Reserve space for VLAN tag reconstruction */ val = VLAN_TAG_LEN; if (setsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, &val, sizeof(val)) < 0) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't set up reserve on packet socket: %s", pcap_strerror(errno)); return -1; } return 0; } #endif /* defined HAVE_TPACKET2 || defined HAVE_TPACKET3 */ /* * Attempt to set the socket to version 3 of the memory-mapped header and, * if that fails because version 3 isn't supported, attempt to fall * back to version 2. If version 2 isn't supported, just leave it at * version 1. * * Return 1 if we succeed or if we fail because neither version 2 nor 3 is * supported; return -1 on any other error, and set handle->errbuf. */ static int prepare_tpacket_socket(pcap_t *handle) { struct pcap_linux *handlep = handle->priv; #if defined(HAVE_TPACKET2) || defined(HAVE_TPACKET3) int ret; #endif handlep->tp_version = TPACKET_V1; handlep->tp_hdrlen = sizeof(struct tpacket_hdr); #ifdef HAVE_TPACKET3 /* * The only mode in which buffering is done on PF_PACKET * sockets, so that packets might not be delivered * immediately, is TPACKET_V3 mode. * * The buffering cannot be disabled in that mode, so * if the user has requested immediate mode, we don't * use TPACKET_V3. */ if (handle->opt.immediate) ret = 1; /* pretend TPACKET_V3 couldn't be set */ else ret = init_tpacket(handle, TPACKET_V3, "TPACKET_V3"); if (-1 == ret) { /* Error during setting up TPACKET_V3. */ return -1; } else if (1 == ret) { /* TPACKET_V3 not supported - fall back to TPACKET_V2. */ #endif /* HAVE_TPACKET3 */ #ifdef HAVE_TPACKET2 ret = init_tpacket(handle, TPACKET_V2, "TPACKET_V2"); if (-1 == ret) { /* Error during setting up TPACKET_V2. */ return -1; } #endif /* HAVE_TPACKET2 */ #ifdef HAVE_TPACKET3 } #endif /* HAVE_TPACKET3 */ return 1; } /* * Attempt to set up memory-mapped access. * * On success, returns 1, and sets *status to 0 if there are no warnings * or to a PCAP_WARNING_ code if there is a warning. * * On failure due to lack of support for memory-mapped capture, returns * 0. * * On error, returns -1, and sets *status to the appropriate error code; * if that is PCAP_ERROR, sets handle->errbuf to the appropriate message. */ static int create_ring(pcap_t *handle, int *status) { struct pcap_linux *handlep = handle->priv; unsigned i, j, frames_per_block; #ifdef HAVE_TPACKET3 /* * For sockets using TPACKET_V1 or TPACKET_V2, the extra * stuff at the end of a struct tpacket_req3 will be * ignored, so this is OK even for those sockets. */ struct tpacket_req3 req; #else struct tpacket_req req; #endif socklen_t len; unsigned int sk_type, tp_reserve, maclen, tp_hdrlen, netoff, macoff; unsigned int frame_size; /* * Start out assuming no warnings or errors. */ *status = 0; switch (handlep->tp_version) { case TPACKET_V1: #ifdef HAVE_TPACKET2 case TPACKET_V2: #endif /* Note that with large snapshot length (say 64K, which is * the default for recent versions of tcpdump, the value that * "-s 0" has given for a long time with tcpdump, and the * default in Wireshark/TShark/dumpcap), if we use the snapshot * length to calculate the frame length, only a few frames * will be available in the ring even with pretty * large ring size (and a lot of memory will be unused). * * Ideally, we should choose a frame length based on the * minimum of the specified snapshot length and the maximum * packet size. That's not as easy as it sounds; consider, * for example, an 802.11 interface in monitor mode, where * the frame would include a radiotap header, where the * maximum radiotap header length is device-dependent. * * So, for now, we just do this for Ethernet devices, where * there's no metadata header, and the link-layer header is * fixed length. We can get the maximum packet size by * adding 18, the Ethernet header length plus the CRC length * (just in case we happen to get the CRC in the packet), to * the MTU of the interface; we fetch the MTU in the hopes * that it reflects support for jumbo frames. (Even if the * interface is just being used for passive snooping, the * driver might set the size of buffers in the receive ring * based on the MTU, so that the MTU limits the maximum size * of packets that we can receive.) * * We don't do that if segmentation/fragmentation or receive * offload are enabled, so we don't get rudely surprised by * "packets" bigger than the MTU. */ frame_size = handle->snapshot; if (handle->linktype == DLT_EN10MB) { int mtu; int offload; offload = iface_get_offload(handle); if (offload == -1) { *status = PCAP_ERROR; return -1; } if (!offload) { mtu = iface_get_mtu(handle->fd, handle->opt.source, handle->errbuf); if (mtu == -1) { *status = PCAP_ERROR; return -1; } if (frame_size > mtu + 18) frame_size = mtu + 18; } } /* NOTE: calculus matching those in tpacket_rcv() * in linux-2.6/net/packet/af_packet.c */ len = sizeof(sk_type); if (getsockopt(handle->fd, SOL_SOCKET, SO_TYPE, &sk_type, &len) < 0) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "getsockopt: %s", pcap_strerror(errno)); *status = PCAP_ERROR; return -1; } #ifdef PACKET_RESERVE len = sizeof(tp_reserve); if (getsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, &tp_reserve, &len) < 0) { if (errno != ENOPROTOOPT) { /* * ENOPROTOOPT means "kernel doesn't support * PACKET_RESERVE", in which case we fall back * as best we can. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "getsockopt: %s", pcap_strerror(errno)); *status = PCAP_ERROR; return -1; } tp_reserve = 0; /* older kernel, reserve not supported */ } #else tp_reserve = 0; /* older kernel, reserve not supported */ #endif maclen = (sk_type == SOCK_DGRAM) ? 0 : MAX_LINKHEADER_SIZE; /* XXX: in the kernel maclen is calculated from * LL_ALLOCATED_SPACE(dev) and vnet_hdr.hdr_len * in: packet_snd() in linux-2.6/net/packet/af_packet.c * then packet_alloc_skb() in linux-2.6/net/packet/af_packet.c * then sock_alloc_send_pskb() in linux-2.6/net/core/sock.c * but I see no way to get those sizes in userspace, * like for instance with an ifreq ioctl(); * the best thing I've found so far is MAX_HEADER in * the kernel part of linux-2.6/include/linux/netdevice.h * which goes up to 128+48=176; since pcap-linux.c * defines a MAX_LINKHEADER_SIZE of 256 which is * greater than that, let's use it.. maybe is it even * large enough to directly replace macoff.. */ tp_hdrlen = TPACKET_ALIGN(handlep->tp_hdrlen) + sizeof(struct sockaddr_ll) ; netoff = TPACKET_ALIGN(tp_hdrlen + (maclen < 16 ? 16 : maclen)) + tp_reserve; /* NOTE: AFAICS tp_reserve may break the TPACKET_ALIGN * of netoff, which contradicts * linux-2.6/Documentation/networking/packet_mmap.txt * documenting that: * "- Gap, chosen so that packet data (Start+tp_net) * aligns to TPACKET_ALIGNMENT=16" */ /* NOTE: in linux-2.6/include/linux/skbuff.h: * "CPUs often take a performance hit * when accessing unaligned memory locations" */ macoff = netoff - maclen; req.tp_frame_size = TPACKET_ALIGN(macoff + frame_size); req.tp_frame_nr = handle->opt.buffer_size/req.tp_frame_size; break; #ifdef HAVE_TPACKET3 case TPACKET_V3: /* The "frames" for this are actually buffers that * contain multiple variable-sized frames. * * We pick a "frame" size of 128K to leave enough * room for at least one reasonably-sized packet * in the "frame". */ req.tp_frame_size = MAXIMUM_SNAPLEN; req.tp_frame_nr = handle->opt.buffer_size/req.tp_frame_size; break; #endif } /* compute the minumum block size that will handle this frame. * The block has to be page size aligned. * The max block size allowed by the kernel is arch-dependent and * it's not explicitly checked here. */ req.tp_block_size = getpagesize(); while (req.tp_block_size < req.tp_frame_size) req.tp_block_size <<= 1; frames_per_block = req.tp_block_size/req.tp_frame_size; /* * PACKET_TIMESTAMP was added after linux/net_tstamp.h was, * so we check for PACKET_TIMESTAMP. We check for * linux/net_tstamp.h just in case a system somehow has * PACKET_TIMESTAMP but not linux/net_tstamp.h; that might * be unnecessary. * * SIOCSHWTSTAMP was introduced in the patch that introduced * linux/net_tstamp.h, so we don't bother checking whether * SIOCSHWTSTAMP is defined (if your Linux system has * linux/net_tstamp.h but doesn't define SIOCSHWTSTAMP, your * Linux system is badly broken). */ #if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) /* * If we were told to do so, ask the kernel and the driver * to use hardware timestamps. * * Hardware timestamps are only supported with mmapped * captures. */ if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER || handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER_UNSYNCED) { struct hwtstamp_config hwconfig; struct ifreq ifr; int timesource; /* * Ask for hardware time stamps on all packets, * including transmitted packets. */ memset(&hwconfig, 0, sizeof(hwconfig)); hwconfig.tx_type = HWTSTAMP_TX_ON; hwconfig.rx_filter = HWTSTAMP_FILTER_ALL; memset(&ifr, 0, sizeof(ifr)); strlcpy(ifr.ifr_name, handle->opt.source, sizeof(ifr.ifr_name)); ifr.ifr_data = (void *)&hwconfig; if (ioctl(handle->fd, SIOCSHWTSTAMP, &ifr) < 0) { switch (errno) { case EPERM: /* * Treat this as an error, as the * user should try to run this * with the appropriate privileges - * and, if they can't, shouldn't * try requesting hardware time stamps. */ *status = PCAP_ERROR_PERM_DENIED; return -1; case EOPNOTSUPP: /* * Treat this as a warning, as the * only way to fix the warning is to * get an adapter that supports hardware * time stamps. We'll just fall back * on the standard host time stamps. */ *status = PCAP_WARNING_TSTAMP_TYPE_NOTSUP; break; default: snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SIOCSHWTSTAMP failed: %s", pcap_strerror(errno)); *status = PCAP_ERROR; return -1; } } else { /* * Well, that worked. Now specify the type of * hardware time stamp we want for this * socket. */ if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER) { /* * Hardware timestamp, synchronized * with the system clock. */ timesource = SOF_TIMESTAMPING_SYS_HARDWARE; } else { /* * PCAP_TSTAMP_ADAPTER_UNSYNCED - hardware * timestamp, not synchronized with the * system clock. */ timesource = SOF_TIMESTAMPING_RAW_HARDWARE; } if (setsockopt(handle->fd, SOL_PACKET, PACKET_TIMESTAMP, (void *)×ource, sizeof(timesource))) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't set PACKET_TIMESTAMP: %s", pcap_strerror(errno)); *status = PCAP_ERROR; return -1; } } } #endif /* HAVE_LINUX_NET_TSTAMP_H && PACKET_TIMESTAMP */ /* ask the kernel to create the ring */ retry: req.tp_block_nr = req.tp_frame_nr / frames_per_block; /* req.tp_frame_nr is requested to match frames_per_block*req.tp_block_nr */ req.tp_frame_nr = req.tp_block_nr * frames_per_block; #ifdef HAVE_TPACKET3 /* timeout value to retire block - use the configured buffering timeout, or default if <0. */ req.tp_retire_blk_tov = (handlep->timeout>=0)?handlep->timeout:0; /* private data not used */ req.tp_sizeof_priv = 0; /* Rx ring - feature request bits - none (rxhash will not be filled) */ req.tp_feature_req_word = 0; #endif if (setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING, (void *) &req, sizeof(req))) { if ((errno == ENOMEM) && (req.tp_block_nr > 1)) { /* * Memory failure; try to reduce the requested ring * size. * * We used to reduce this by half -- do 5% instead. * That may result in more iterations and a longer * startup, but the user will be much happier with * the resulting buffer size. */ if (req.tp_frame_nr < 20) req.tp_frame_nr -= 1; else req.tp_frame_nr -= req.tp_frame_nr/20; goto retry; } if (errno == ENOPROTOOPT) { /* * We don't have ring buffer support in this kernel. */ return 0; } snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't create rx ring on packet socket: %s", pcap_strerror(errno)); *status = PCAP_ERROR; return -1; } /* memory map the rx ring */ handlep->mmapbuflen = req.tp_block_nr * req.tp_block_size; handlep->mmapbuf = mmap(0, handlep->mmapbuflen, PROT_READ|PROT_WRITE, MAP_SHARED, handle->fd, 0); if (handlep->mmapbuf == MAP_FAILED) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't mmap rx ring: %s", pcap_strerror(errno)); /* clear the allocated ring on error*/ destroy_ring(handle); *status = PCAP_ERROR; return -1; } /* allocate a ring for each frame header pointer*/ handle->cc = req.tp_frame_nr; handle->buffer = malloc(handle->cc * sizeof(union thdr *)); if (!handle->buffer) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't allocate ring of frame headers: %s", pcap_strerror(errno)); destroy_ring(handle); *status = PCAP_ERROR; return -1; } /* fill the header ring with proper frame ptr*/ handle->offset = 0; for (i=0; i<req.tp_block_nr; ++i) { void *base = &handlep->mmapbuf[i*req.tp_block_size]; for (j=0; j<frames_per_block; ++j, ++handle->offset) { RING_GET_FRAME(handle) = base; base += req.tp_frame_size; } } handle->bufsize = req.tp_frame_size; handle->offset = 0; return 1; } /* free all ring related resources*/ static void destroy_ring(pcap_t *handle) { struct pcap_linux *handlep = handle->priv; /* tell the kernel to destroy the ring*/ struct tpacket_req req; memset(&req, 0, sizeof(req)); /* do not test for setsockopt failure, as we can't recover from any error */ (void)setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING, (void *) &req, sizeof(req)); /* if ring is mapped, unmap it*/ if (handlep->mmapbuf) { /* do not test for mmap failure, as we can't recover from any error */ (void)munmap(handlep->mmapbuf, handlep->mmapbuflen); handlep->mmapbuf = NULL; } } /* * Special one-shot callback, used for pcap_next() and pcap_next_ex(), * for Linux mmapped capture. * * The problem is that pcap_next() and pcap_next_ex() expect the packet * data handed to the callback to be valid after the callback returns, * but pcap_read_linux_mmap() has to release that packet as soon as * the callback returns (otherwise, the kernel thinks there's still * at least one unprocessed packet available in the ring, so a select() * will immediately return indicating that there's data to process), so, * in the callback, we have to make a copy of the packet. * * Yes, this means that, if the capture is using the ring buffer, using * pcap_next() or pcap_next_ex() requires more copies than using * pcap_loop() or pcap_dispatch(). If that bothers you, don't use * pcap_next() or pcap_next_ex(). */ static void pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h, const u_char *bytes) { struct oneshot_userdata *sp = (struct oneshot_userdata *)user; pcap_t *handle = sp->pd; struct pcap_linux *handlep = handle->priv; *sp->hdr = *h; memcpy(handlep->oneshot_buffer, bytes, h->caplen); *sp->pkt = handlep->oneshot_buffer; } static void pcap_cleanup_linux_mmap( pcap_t *handle ) { struct pcap_linux *handlep = handle->priv; destroy_ring(handle); if (handlep->oneshot_buffer != NULL) { free(handlep->oneshot_buffer); handlep->oneshot_buffer = NULL; } pcap_cleanup_linux(handle); } static int pcap_getnonblock_mmap(pcap_t *p, char *errbuf) { struct pcap_linux *handlep = p->priv; /* use negative value of timeout to indicate non blocking ops */ return (handlep->timeout<0); } static int pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf) { struct pcap_linux *handlep = p->priv; /* * Set the file descriptor to non-blocking mode, as we use * it for sending packets. */ if (pcap_setnonblock_fd(p, nonblock, errbuf) == -1) return -1; /* * Map each value to their corresponding negation to * preserve the timeout value provided with pcap_set_timeout. */ if (nonblock) { if (handlep->timeout >= 0) { /* * Indicate that we're switching to * non-blocking mode. */ handlep->timeout = ~handlep->timeout; } } else { if (handlep->timeout < 0) { handlep->timeout = ~handlep->timeout; } } return 0; } static inline union thdr * pcap_get_ring_frame(pcap_t *handle, int status) { struct pcap_linux *handlep = handle->priv; union thdr h; h.raw = RING_GET_FRAME(handle); switch (handlep->tp_version) { case TPACKET_V1: if (status != (h.h1->tp_status ? TP_STATUS_USER : TP_STATUS_KERNEL)) return NULL; break; #ifdef HAVE_TPACKET2 case TPACKET_V2: if (status != (h.h2->tp_status ? TP_STATUS_USER : TP_STATUS_KERNEL)) return NULL; break; #endif #ifdef HAVE_TPACKET3 case TPACKET_V3: if (status != (h.h3->hdr.bh1.block_status ? TP_STATUS_USER : TP_STATUS_KERNEL)) return NULL; break; #endif } return h.raw; } #ifndef POLLRDHUP #define POLLRDHUP 0 #endif /* wait for frames availability.*/ static int pcap_wait_for_frames_mmap(pcap_t *handle) { if (!pcap_get_ring_frame(handle, TP_STATUS_USER)) { struct pcap_linux *handlep = handle->priv; int timeout; char c; struct pollfd pollinfo; int ret; pollinfo.fd = handle->fd; pollinfo.events = POLLIN; if (handlep->timeout == 0) { #ifdef HAVE_TPACKET3 /* * XXX - due to a set of (mis)features in the * TPACKET_V3 kernel code, blocking forever with * a TPACKET_V3 socket can, if few packets * are arriving and passing the socket filter, * cause most packets to be dropped. See * libpcap issue #335 for the full painful * story. The workaround is to have poll() * time out very quickly, so we grab the * frames handed to us, and return them to * the kernel, ASAP. * * If those issues are ever fixed, we might * want to check the kernel version and block * forever with TPACKET_V3 if we're running * with a kernel that has the fix. */ if (handlep->tp_version == TPACKET_V3) timeout = 1; /* don't block for very long */ else #endif timeout = -1; /* block forever */ } else if (handlep->timeout > 0) timeout = handlep->timeout; /* block for that amount of time */ else timeout = 0; /* non-blocking mode - poll to pick up errors */ do { ret = poll(&pollinfo, 1, timeout); if (ret < 0 && errno != EINTR) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't poll on packet socket: %s", pcap_strerror(errno)); return PCAP_ERROR; } else if (ret > 0 && (pollinfo.revents & (POLLHUP|POLLRDHUP|POLLERR|POLLNVAL))) { /* * There's some indication other than * "you can read on this descriptor" on * the descriptor. */ if (pollinfo.revents & (POLLHUP | POLLRDHUP)) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Hangup on packet socket"); return PCAP_ERROR; } if (pollinfo.revents & POLLERR) { /* * A recv() will give us the * actual error code. * * XXX - make the socket non-blocking? */ if (recv(handle->fd, &c, sizeof c, MSG_PEEK) != -1) continue; /* what, no error? */ if (errno == ENETDOWN) { /* * The device on which we're * capturing went away. * * XXX - we should really return * PCAP_ERROR_IFACE_NOT_UP, * but pcap_dispatch() etc. * aren't defined to return * that. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "The interface went down"); } else { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Error condition on packet socket: %s", strerror(errno)); } return PCAP_ERROR; } if (pollinfo.revents & POLLNVAL) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Invalid polling request on packet socket"); return PCAP_ERROR; } } /* check for break loop condition on interrupted syscall*/ if (handle->break_loop) { handle->break_loop = 0; return PCAP_ERROR_BREAK; } } while (ret < 0); } return 0; } /* handle a single memory mapped packet */ static int pcap_handle_packet_mmap( pcap_t *handle, pcap_handler callback, u_char *user, unsigned char *frame, unsigned int tp_len, unsigned int tp_mac, unsigned int tp_snaplen, unsigned int tp_sec, unsigned int tp_usec, int tp_vlan_tci_valid, __u16 tp_vlan_tci) { struct pcap_linux *handlep = handle->priv; unsigned char *bp; struct sockaddr_ll *sll; struct pcap_pkthdr pcaphdr; /* perform sanity check on internal offset. */ if (tp_mac + tp_snaplen > handle->bufsize) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "corrupted frame on kernel ring mac " "offset %d + caplen %d > frame len %d", tp_mac, tp_snaplen, handle->bufsize); return -1; } /* run filter on received packet * If the kernel filtering is enabled we need to run the * filter until all the frames present into the ring * at filter creation time are processed. * In this case, blocks_to_filter_in_userland is used * as a counter for the packet we need to filter. * Note: alternatively it could be possible to stop applying * the filter when the ring became empty, but it can possibly * happen a lot later... */ bp = frame + tp_mac; if (handlep->filter_in_userland && handle->fcode.bf_insns) { struct bpf_aux_data aux_data; aux_data.vlan_tag = tp_vlan_tci & 0x0fff; aux_data.vlan_tag_present = tp_vlan_tci_valid; if (bpf_filter_with_aux_data(handle->fcode.bf_insns, bp, tp_len, tp_snaplen, &aux_data) == 0) return 0; } sll = (void *)frame + TPACKET_ALIGN(handlep->tp_hdrlen); if (!linux_check_direction(handle, sll)) return 0; /* get required packet info from ring header */ pcaphdr.ts.tv_sec = tp_sec; pcaphdr.ts.tv_usec = tp_usec; pcaphdr.caplen = tp_snaplen; pcaphdr.len = tp_len; /* if required build in place the sll header*/ if (handlep->cooked) { struct sll_header *hdrp; /* * The kernel should have left us with enough * space for an sll header; back up the packet * data pointer into that space, as that'll be * the beginning of the packet we pass to the * callback. */ bp -= SLL_HDR_LEN; /*/* * Let's make sure that's past the end of * the tpacket header, i.e. >= * ((u_char *)thdr + TPACKET_HDRLEN), so we * don't step on the header when we construct * the sll header. */ if (bp < (u_char *)frame + TPACKET_ALIGN(handlep->tp_hdrlen) + sizeof(struct sockaddr_ll)) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "cooked-mode frame doesn't have room for sll header"); return -1; } /* * OK, that worked; construct the sll header. */ hdrp = (struct sll_header *)bp; hdrp->sll_pkttype = map_packet_type_to_sll_type( sll->sll_pkttype); hdrp->sll_hatype = htons(sll->sll_hatype); hdrp->sll_halen = htons(sll->sll_halen); memcpy(hdrp->sll_addr, sll->sll_addr, SLL_ADDRLEN); hdrp->sll_protocol = sll->sll_protocol; /* update packet len */ pcaphdr.caplen += SLL_HDR_LEN; pcaphdr.len += SLL_HDR_LEN; } #if defined(HAVE_TPACKET2) || defined(HAVE_TPACKET3) if (tp_vlan_tci_valid && handlep->vlan_offset != -1 && tp_snaplen >= (unsigned int) handlep->vlan_offset) { struct vlan_tag *tag; bp -= VLAN_TAG_LEN; memmove(bp, bp + VLAN_TAG_LEN, handlep->vlan_offset); tag = (struct vlan_tag *)(bp + handlep->vlan_offset); tag->vlan_tpid = htons(ETH_P_8021Q); tag->vlan_tci = htons(tp_vlan_tci); pcaphdr.caplen += VLAN_TAG_LEN; pcaphdr.len += VLAN_TAG_LEN; } #endif /* * The only way to tell the kernel to cut off the * packet at a snapshot length is with a filter program; * if there's no filter program, the kernel won't cut * the packet off. * * Trim the snapshot length to be no longer than the * specified snapshot length. */ if (pcaphdr.caplen > handle->snapshot) pcaphdr.caplen = handle->snapshot; /* pass the packet to the user */ callback(user, &pcaphdr, bp); return 1; } static int pcap_read_linux_mmap_v1(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) { struct pcap_linux *handlep = handle->priv; int pkts = 0; int ret; /* wait for frames availability.*/ ret = pcap_wait_for_frames_mmap(handle); if (ret) { return ret; } /* non-positive values of max_packets are used to require all * packets currently available in the ring */ while ((pkts < max_packets) || PACKET_COUNT_IS_UNLIMITED(max_packets)) { union thdr h; h.raw = pcap_get_ring_frame(handle, TP_STATUS_USER); if (!h.raw) break; ret = pcap_handle_packet_mmap( handle, callback, user, h.raw, h.h1->tp_len, h.h1->tp_mac, h.h1->tp_snaplen, h.h1->tp_sec, h.h1->tp_usec, 0, 0); if (ret == 1) { pkts++; handlep->packets_read++; } else if (ret < 0) { return ret; } /* * Hand this block back to the kernel, and, if we're * counting blocks that need to be filtered in userland * after having been filtered by the kernel, count * the one we've just processed. */ h.h1->tp_status = TP_STATUS_KERNEL; if (handlep->blocks_to_filter_in_userland > 0) { handlep->blocks_to_filter_in_userland--; if (handlep->blocks_to_filter_in_userland == 0) { /* * No more blocks need to be filtered * in userland. */ handlep->filter_in_userland = 0; } } /* next block */ if (++handle->offset >= handle->cc) handle->offset = 0; /* check for break loop condition*/ if (handle->break_loop) { handle->break_loop = 0; return PCAP_ERROR_BREAK; } } return pkts; } #ifdef HAVE_TPACKET2 static int pcap_read_linux_mmap_v2(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) { struct pcap_linux *handlep = handle->priv; int pkts = 0; int ret; /* wait for frames availability.*/ ret = pcap_wait_for_frames_mmap(handle); if (ret) { return ret; } /* non-positive values of max_packets are used to require all * packets currently available in the ring */ while ((pkts < max_packets) || PACKET_COUNT_IS_UNLIMITED(max_packets)) { union thdr h; h.raw = pcap_get_ring_frame(handle, TP_STATUS_USER); if (!h.raw) break; ret = pcap_handle_packet_mmap( handle, callback, user, h.raw, h.h2->tp_len, h.h2->tp_mac, h.h2->tp_snaplen, h.h2->tp_sec, handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO ? h.h2->tp_nsec : h.h2->tp_nsec / 1000, #if defined(TP_STATUS_VLAN_VALID) (h.h2->tp_vlan_tci || (h.h2->tp_status & TP_STATUS_VLAN_VALID)), #else h.h2->tp_vlan_tci != 0, #endif h.h2->tp_vlan_tci); if (ret == 1) { pkts++; handlep->packets_read++; } else if (ret < 0) { return ret; } /* * Hand this block back to the kernel, and, if we're * counting blocks that need to be filtered in userland * after having been filtered by the kernel, count * the one we've just processed. */ h.h2->tp_status = TP_STATUS_KERNEL; if (handlep->blocks_to_filter_in_userland > 0) { handlep->blocks_to_filter_in_userland--; if (handlep->blocks_to_filter_in_userland == 0) { /* * No more blocks need to be filtered * in userland. */ handlep->filter_in_userland = 0; } } /* next block */ if (++handle->offset >= handle->cc) handle->offset = 0; /* check for break loop condition*/ if (handle->break_loop) { handle->break_loop = 0; return PCAP_ERROR_BREAK; } } return pkts; } #endif /* HAVE_TPACKET2 */ #ifdef HAVE_TPACKET3 static int pcap_read_linux_mmap_v3(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) { struct pcap_linux *handlep = handle->priv; union thdr h; int pkts = 0; int ret; again: if (handlep->current_packet == NULL) { /* wait for frames availability.*/ ret = pcap_wait_for_frames_mmap(handle); if (ret) { return ret; } } h.raw = pcap_get_ring_frame(handle, TP_STATUS_USER); if (!h.raw) { if (pkts == 0 && handlep->timeout == 0) { /* Block until we see a packet. */ goto again; } return pkts; } /* non-positive values of max_packets are used to require all * packets currently available in the ring */ while ((pkts < max_packets) || PACKET_COUNT_IS_UNLIMITED(max_packets)) { if (handlep->current_packet == NULL) { h.raw = pcap_get_ring_frame(handle, TP_STATUS_USER); if (!h.raw) break; handlep->current_packet = h.raw + h.h3->hdr.bh1.offset_to_first_pkt; handlep->packets_left = h.h3->hdr.bh1.num_pkts; } int packets_to_read = handlep->packets_left; if (!PACKET_COUNT_IS_UNLIMITED(max_packets) && packets_to_read > max_packets) { packets_to_read = max_packets; } while(packets_to_read--) { struct tpacket3_hdr* tp3_hdr = (struct tpacket3_hdr*) handlep->current_packet; ret = pcap_handle_packet_mmap( handle, callback, user, handlep->current_packet, tp3_hdr->tp_len, tp3_hdr->tp_mac, tp3_hdr->tp_snaplen, tp3_hdr->tp_sec, handle->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO ? tp3_hdr->tp_nsec : tp3_hdr->tp_nsec / 1000, #if defined(TP_STATUS_VLAN_VALID) (tp3_hdr->hv1.tp_vlan_tci || (tp3_hdr->tp_status & TP_STATUS_VLAN_VALID)), #else tp3_hdr->hv1.tp_vlan_tci != 0, #endif tp3_hdr->hv1.tp_vlan_tci); if (ret == 1) { pkts++; handlep->packets_read++; } else if (ret < 0) { handlep->current_packet = NULL; return ret; } handlep->current_packet += tp3_hdr->tp_next_offset; handlep->packets_left--; } if (handlep->packets_left <= 0) { /* * Hand this block back to the kernel, and, if * we're counting blocks that need to be * filtered in userland after having been * filtered by the kernel, count the one we've * just processed. */ h.h3->hdr.bh1.block_status = TP_STATUS_KERNEL; if (handlep->blocks_to_filter_in_userland > 0) { handlep->blocks_to_filter_in_userland--; if (handlep->blocks_to_filter_in_userland == 0) { /* * No more blocks need to be filtered * in userland. */ handlep->filter_in_userland = 0; } } /* next block */ if (++handle->offset >= handle->cc) handle->offset = 0; handlep->current_packet = NULL; } /* check for break loop condition*/ if (handle->break_loop) { handle->break_loop = 0; return PCAP_ERROR_BREAK; } } if (pkts == 0 && handlep->timeout == 0) { /* Block until we see a packet. */ goto again; } return pkts; } #endif /* HAVE_TPACKET3 */ static int pcap_setfilter_linux_mmap(pcap_t *handle, struct bpf_program *filter) { struct pcap_linux *handlep = handle->priv; int n, offset; int ret; /* * Don't rewrite "ret" instructions; we don't need to, as * we're not reading packets with recvmsg(), and we don't * want to, as, by not rewriting them, the kernel can avoid * copying extra data. */ ret = pcap_setfilter_linux_common(handle, filter, 1); if (ret < 0) return ret; /* * If we're filtering in userland, there's nothing to do; * the new filter will be used for the next packet. */ if (handlep->filter_in_userland) return ret; /* * We're filtering in the kernel; the packets present in * all blocks currently in the ring were already filtered * by the old filter, and so will need to be filtered in * userland by the new filter. * * Get an upper bound for the number of such blocks; first, * walk the ring backward and count the free blocks. */ offset = handle->offset; if (--handle->offset < 0) handle->offset = handle->cc - 1; for (n=0; n < handle->cc; ++n) { if (--handle->offset < 0) handle->offset = handle->cc - 1; if (!pcap_get_ring_frame(handle, TP_STATUS_KERNEL)) break; } /* * If we found free blocks, decrement the count of free * blocks by 1, just in case we lost a race with another * thread of control that was adding a packet while * we were counting and that had run the filter before * we changed it. * * XXX - could there be more than one block added in * this fashion? * * XXX - is there a way to avoid that race, e.g. somehow * wait for all packets that passed the old filter to * be added to the ring? */ if (n != 0) n--; /* be careful to not change current ring position */ handle->offset = offset; /* * Set the count of blocks worth of packets to filter * in userland to the total number of blocks in the * ring minus the number of free blocks we found, and * turn on userland filtering. (The count of blocks * worth of packets to filter in userland is guaranteed * not to be zero - n, above, couldn't be set to a * value > handle->cc, and if it were equal to * handle->cc, it wouldn't be zero, and thus would * be decremented to handle->cc - 1.) */ handlep->blocks_to_filter_in_userland = handle->cc - n; handlep->filter_in_userland = 1; return ret; } #endif /* HAVE_PACKET_RING */ #ifdef HAVE_PF_PACKET_SOCKETS /* * Return the index of the given device name. Fill ebuf and return * -1 on failure. */ static int iface_get_id(int fd, const char *device, char *ebuf) { struct ifreq ifr; memset(&ifr, 0, sizeof(ifr)); strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "SIOCGIFINDEX: %s", pcap_strerror(errno)); return -1; } return ifr.ifr_ifindex; } /* * Bind the socket associated with FD to the given device. * Return 1 on success, 0 if we should try a SOCK_PACKET socket, * or a PCAP_ERROR_ value on a hard error. */ static int iface_bind(int fd, int ifindex, char *ebuf) { struct sockaddr_ll sll; int err; socklen_t errlen = sizeof(err); memset(&sll, 0, sizeof(sll)); sll.sll_family = AF_PACKET; sll.sll_ifindex = ifindex; sll.sll_protocol = htons(ETH_P_ALL); if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) == -1) { if (errno == ENETDOWN) { /* * Return a "network down" indication, so that * the application can report that rather than * saying we had a mysterious failure and * suggest that they report a problem to the * libpcap developers. */ return PCAP_ERROR_IFACE_NOT_UP; } else { snprintf(ebuf, PCAP_ERRBUF_SIZE, "bind: %s", pcap_strerror(errno)); return PCAP_ERROR; } } /* Any pending errors, e.g., network is down? */ if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "getsockopt: %s", pcap_strerror(errno)); return 0; } if (err == ENETDOWN) { /* * Return a "network down" indication, so that * the application can report that rather than * saying we had a mysterious failure and * suggest that they report a problem to the * libpcap developers. */ return PCAP_ERROR_IFACE_NOT_UP; } else if (err > 0) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "bind: %s", pcap_strerror(err)); return 0; } return 1; } #ifdef IW_MODE_MONITOR /* * Check whether the device supports the Wireless Extensions. * Returns 1 if it does, 0 if it doesn't, PCAP_ERROR_NO_SUCH_DEVICE * if the device doesn't even exist. */ static int has_wext(int sock_fd, const char *device, char *ebuf) { struct iwreq ireq; strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); if (ioctl(sock_fd, SIOCGIWNAME, &ireq) >= 0) return 1; /* yes */ snprintf(ebuf, PCAP_ERRBUF_SIZE, "%s: SIOCGIWPRIV: %s", device, pcap_strerror(errno)); if (errno == ENODEV) return PCAP_ERROR_NO_SUCH_DEVICE; return 0; } /* * Per me si va ne la citta dolente, * Per me si va ne l'etterno dolore, * ... * Lasciate ogne speranza, voi ch'intrate. * * XXX - airmon-ng does special stuff with the Orinoco driver and the * wlan-ng driver. */ typedef enum { MONITOR_WEXT, MONITOR_HOSTAP, MONITOR_PRISM, MONITOR_PRISM54, MONITOR_ACX100, MONITOR_RT2500, MONITOR_RT2570, MONITOR_RT73, MONITOR_RTL8XXX } monitor_type; /* * Use the Wireless Extensions, if we have them, to try to turn monitor mode * on if it's not already on. * * Returns 1 on success, 0 if we don't support the Wireless Extensions * on this device, or a PCAP_ERROR_ value if we do support them but * we weren't able to turn monitor mode on. */ static int enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device) { /* * XXX - at least some adapters require non-Wireless Extensions * mechanisms to turn monitor mode on. * * Atheros cards might require that a separate "monitor virtual access * point" be created, with later versions of the madwifi driver. * airmon-ng does "wlanconfig ath create wlandev {if} wlanmode * monitor -bssid", which apparently spits out a line "athN" * where "athN" is the monitor mode device. To leave monitor * mode, it destroys the monitor mode device. * * Some Intel Centrino adapters might require private ioctls to get * radio headers; the ipw2200 and ipw3945 drivers allow you to * configure a separate "rtapN" interface to capture in monitor * mode without preventing the adapter from operating normally. * (airmon-ng doesn't appear to use that, though.) * * It would be Truly Wonderful if mac80211 and nl80211 cleaned this * up, and if all drivers were converted to mac80211 drivers. * * If interface {if} is a mac80211 driver, the file * /sys/class/net/{if}/phy80211 is a symlink to * /sys/class/ieee80211/{phydev}, for some {phydev}. * * On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at * least, has a "wmaster0" device and a "wlan0" device; the * latter is the one with the IP address. Both show up in * "tcpdump -D" output. Capturing on the wmaster0 device * captures with 802.11 headers. * * airmon-ng searches through /sys/class/net for devices named * monN, starting with mon0; as soon as one *doesn't* exist, * it chooses that as the monitor device name. If the "iw" * command exists, it does "iw dev {if} interface add {monif} * type monitor", where {monif} is the monitor device. It * then (sigh) sleeps .1 second, and then configures the * device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface * is a file, it writes {mondev}, without a newline, to that file, * and again (sigh) sleeps .1 second, and then iwconfig's that * device into monitor mode and configures it up. Otherwise, * you can't do monitor mode. * * All these devices are "glued" together by having the * /sys/class/net/{device}/phy80211 links pointing to the same * place, so, given a wmaster, wlan, or mon device, you can * find the other devices by looking for devices with * the same phy80211 link. * * To turn monitor mode off, delete the monitor interface, * either with "iw dev {monif} interface del" or by sending * {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface * * Note: if you try to create a monitor device named "monN", and * there's already a "monN" device, it fails, as least with * the netlink interface (which is what iw uses), with a return * value of -ENFILE. (Return values are negative errnos.) We * could probably use that to find an unused device. */ struct pcap_linux *handlep = handle->priv; int err; struct iwreq ireq; struct iw_priv_args *priv; monitor_type montype; int i; __u32 cmd; struct ifreq ifr; int oldflags; int args[2]; int channel; /* * Does this device *support* the Wireless Extensions? */ err = has_wext(sock_fd, device, handle->errbuf); if (err <= 0) return err; /* either it doesn't or the device doesn't even exist */ /* * Start out assuming we have no private extensions to control * radio metadata. */ montype = MONITOR_WEXT; cmd = 0; /* * Try to get all the Wireless Extensions private ioctls * supported by this device. * * First, get the size of the buffer we need, by supplying no * buffer and a length of 0. If the device supports private * ioctls, it should return E2BIG, with ireq.u.data.length set * to the length we need. If it doesn't support them, it should * return EOPNOTSUPP. */ memset(&ireq, 0, sizeof ireq); strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); ireq.u.data.pointer = (void *)args; ireq.u.data.length = 0; ireq.u.data.flags = 0; if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) != -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: SIOCGIWPRIV with a zero-length buffer didn't fail!", device); return PCAP_ERROR; } if (errno != EOPNOTSUPP) { /* * OK, it's not as if there are no private ioctls. */ if (errno != E2BIG) { /* * Failed. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: SIOCGIWPRIV: %s", device, pcap_strerror(errno)); return PCAP_ERROR; } /* * OK, try to get the list of private ioctls. */ priv = malloc(ireq.u.data.length * sizeof (struct iw_priv_args)); if (priv == NULL) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "malloc: %s", pcap_strerror(errno)); return PCAP_ERROR; } ireq.u.data.pointer = (void *)priv; if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: SIOCGIWPRIV: %s", device, pcap_strerror(errno)); free(priv); return PCAP_ERROR; } /* * Look for private ioctls to turn monitor mode on or, if * monitor mode is on, to set the header type. */ for (i = 0; i < ireq.u.data.length; i++) { if (strcmp(priv[i].name, "monitor_type") == 0) { /* * Hostap driver, use this one. * Set monitor mode first. * You can set it to 0 to get DLT_IEEE80211, * 1 to get DLT_PRISM, 2 to get * DLT_IEEE80211_RADIO_AVS, and, with more * recent versions of the driver, 3 to get * DLT_IEEE80211_RADIO. */ if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) break; if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) break; if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) break; montype = MONITOR_HOSTAP; cmd = priv[i].cmd; break; } if (strcmp(priv[i].name, "set_prismhdr") == 0) { /* * Prism54 driver, use this one. * Set monitor mode first. * You can set it to 2 to get DLT_IEEE80211 * or 3 or get DLT_PRISM. */ if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) break; if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) break; if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) break; montype = MONITOR_PRISM54; cmd = priv[i].cmd; break; } if (strcmp(priv[i].name, "forceprismheader") == 0) { /* * RT2570 driver, use this one. * Do this after turning monitor mode on. * You can set it to 1 to get DLT_PRISM or 2 * to get DLT_IEEE80211. */ if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) break; if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) break; if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) break; montype = MONITOR_RT2570; cmd = priv[i].cmd; break; } if (strcmp(priv[i].name, "forceprism") == 0) { /* * RT73 driver, use this one. * Do this after turning monitor mode on. * Its argument is a *string*; you can * set it to "1" to get DLT_PRISM or "2" * to get DLT_IEEE80211. */ if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_CHAR) break; if (priv[i].set_args & IW_PRIV_SIZE_FIXED) break; montype = MONITOR_RT73; cmd = priv[i].cmd; break; } if (strcmp(priv[i].name, "prismhdr") == 0) { /* * One of the RTL8xxx drivers, use this one. * It can only be done after monitor mode * has been turned on. You can set it to 1 * to get DLT_PRISM or 0 to get DLT_IEEE80211. */ if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) break; if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) break; if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1) break; montype = MONITOR_RTL8XXX; cmd = priv[i].cmd; break; } if (strcmp(priv[i].name, "rfmontx") == 0) { /* * RT2500 or RT61 driver, use this one. * It has one one-byte parameter; set * u.data.length to 1 and u.data.pointer to * point to the parameter. * It doesn't itself turn monitor mode on. * You can set it to 1 to allow transmitting * in monitor mode(?) and get DLT_IEEE80211, * or set it to 0 to disallow transmitting in * monitor mode(?) and get DLT_PRISM. */ if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) break; if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 2) break; montype = MONITOR_RT2500; cmd = priv[i].cmd; break; } if (strcmp(priv[i].name, "monitor") == 0) { /* * Either ACX100 or hostap, use this one. * It turns monitor mode on. * If it takes two arguments, it's ACX100; * the first argument is 1 for DLT_PRISM * or 2 for DLT_IEEE80211, and the second * argument is the channel on which to * run. If it takes one argument, it's * HostAP, and the argument is 2 for * DLT_IEEE80211 and 3 for DLT_PRISM. * * If we see this, we don't quit, as this * might be a version of the hostap driver * that also supports "monitor_type". */ if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT) break; if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED)) break; switch (priv[i].set_args & IW_PRIV_SIZE_MASK) { case 1: montype = MONITOR_PRISM; cmd = priv[i].cmd; break; case 2: montype = MONITOR_ACX100; cmd = priv[i].cmd; break; default: break; } } } free(priv); } /* * XXX - ipw3945? islism? */ /* * Get the old mode. */ strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); if (ioctl(sock_fd, SIOCGIWMODE, &ireq) == -1) { /* * We probably won't be able to set the mode, either. */ return PCAP_ERROR_RFMON_NOTSUP; } /* * Is it currently in monitor mode? */ if (ireq.u.mode == IW_MODE_MONITOR) { /* * Yes. Just leave things as they are. * We don't offer multiple link-layer types, as * changing the link-layer type out from under * somebody else capturing in monitor mode would * be considered rude. */ return 1; } /* * No. We have to put the adapter into rfmon mode. */ /* * If we haven't already done so, arrange to have * "pcap_close_all()" called when we exit. */ if (!pcap_do_addexit(handle)) { /* * "atexit()" failed; don't put the interface * in rfmon mode, just give up. */ return PCAP_ERROR_RFMON_NOTSUP; } /* * Save the old mode. */ handlep->oldmode = ireq.u.mode; /* * Put the adapter in rfmon mode. How we do this depends * on whether we have a special private ioctl or not. */ if (montype == MONITOR_PRISM) { /* * We have the "monitor" private ioctl, but none of * the other private ioctls. Use this, and select * the Prism header. * * If it fails, just fall back on SIOCSIWMODE. */ memset(&ireq, 0, sizeof ireq); strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); ireq.u.data.length = 1; /* 1 argument */ args[0] = 3; /* request Prism header */ memcpy(ireq.u.name, args, sizeof (int)); if (ioctl(sock_fd, cmd, &ireq) != -1) { /* * Success. * Note that we have to put the old mode back * when we close the device. */ handlep->must_do_on_close |= MUST_CLEAR_RFMON; /* * Add this to the list of pcaps to close * when we exit. */ pcap_add_to_pcaps_to_close(handle); return 1; } /* * Failure. Fall back on SIOCSIWMODE. */ } /* * First, take the interface down if it's up; otherwise, we * might get EBUSY. */ memset(&ifr, 0, sizeof(ifr)); strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: Can't get flags: %s", device, strerror(errno)); return PCAP_ERROR; } oldflags = 0; if (ifr.ifr_flags & IFF_UP) { oldflags = ifr.ifr_flags; ifr.ifr_flags &= ~IFF_UP; if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: Can't set flags: %s", device, strerror(errno)); return PCAP_ERROR; } } /* * Then turn monitor mode on. */ strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); ireq.u.mode = IW_MODE_MONITOR; if (ioctl(sock_fd, SIOCSIWMODE, &ireq) == -1) { /* * Scientist, you've failed. * Bring the interface back up if we shut it down. */ ifr.ifr_flags = oldflags; if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: Can't set flags: %s", device, strerror(errno)); return PCAP_ERROR; } return PCAP_ERROR_RFMON_NOTSUP; } /* * XXX - airmon-ng does "iwconfig {if} key off" after setting * monitor mode and setting the channel, and then does * "iwconfig up". */ /* * Now select the appropriate radio header. */ switch (montype) { case MONITOR_WEXT: /* * We don't have any private ioctl to set the header. */ break; case MONITOR_HOSTAP: /* * Try to select the radiotap header. */ memset(&ireq, 0, sizeof ireq); strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); args[0] = 3; /* request radiotap header */ memcpy(ireq.u.name, args, sizeof (int)); if (ioctl(sock_fd, cmd, &ireq) != -1) break; /* success */ /* * That failed. Try to select the AVS header. */ memset(&ireq, 0, sizeof ireq); strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); args[0] = 2; /* request AVS header */ memcpy(ireq.u.name, args, sizeof (int)); if (ioctl(sock_fd, cmd, &ireq) != -1) break; /* success */ /* * That failed. Try to select the Prism header. */ memset(&ireq, 0, sizeof ireq); strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); args[0] = 1; /* request Prism header */ memcpy(ireq.u.name, args, sizeof (int)); ioctl(sock_fd, cmd, &ireq); break; case MONITOR_PRISM: /* * The private ioctl failed. */ break; case MONITOR_PRISM54: /* * Select the Prism header. */ memset(&ireq, 0, sizeof ireq); strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); args[0] = 3; /* request Prism header */ memcpy(ireq.u.name, args, sizeof (int)); ioctl(sock_fd, cmd, &ireq); break; case MONITOR_ACX100: /* * Get the current channel. */ memset(&ireq, 0, sizeof ireq); strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); if (ioctl(sock_fd, SIOCGIWFREQ, &ireq) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: SIOCGIWFREQ: %s", device, pcap_strerror(errno)); return PCAP_ERROR; } channel = ireq.u.freq.m; /* * Select the Prism header, and set the channel to the * current value. */ memset(&ireq, 0, sizeof ireq); strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); args[0] = 1; /* request Prism header */ args[1] = channel; /* set channel */ memcpy(ireq.u.name, args, 2*sizeof (int)); ioctl(sock_fd, cmd, &ireq); break; case MONITOR_RT2500: /* * Disallow transmission - that turns on the * Prism header. */ memset(&ireq, 0, sizeof ireq); strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); args[0] = 0; /* disallow transmitting */ memcpy(ireq.u.name, args, sizeof (int)); ioctl(sock_fd, cmd, &ireq); break; case MONITOR_RT2570: /* * Force the Prism header. */ memset(&ireq, 0, sizeof ireq); strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); args[0] = 1; /* request Prism header */ memcpy(ireq.u.name, args, sizeof (int)); ioctl(sock_fd, cmd, &ireq); break; case MONITOR_RT73: /* * Force the Prism header. */ memset(&ireq, 0, sizeof ireq); strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); ireq.u.data.length = 1; /* 1 argument */ ireq.u.data.pointer = "1"; ireq.u.data.flags = 0; ioctl(sock_fd, cmd, &ireq); break; case MONITOR_RTL8XXX: /* * Force the Prism header. */ memset(&ireq, 0, sizeof ireq); strlcpy(ireq.ifr_ifrn.ifrn_name, device, sizeof ireq.ifr_ifrn.ifrn_name); args[0] = 1; /* request Prism header */ memcpy(ireq.u.name, args, sizeof (int)); ioctl(sock_fd, cmd, &ireq); break; } /* * Now bring the interface back up if we brought it down. */ if (oldflags != 0) { ifr.ifr_flags = oldflags; if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: Can't set flags: %s", device, strerror(errno)); /* * At least try to restore the old mode on the * interface. */ if (ioctl(handle->fd, SIOCSIWMODE, &ireq) == -1) { /* * Scientist, you've failed. */ fprintf(stderr, "Can't restore interface wireless mode (SIOCSIWMODE failed: %s).\n" "Please adjust manually.\n", strerror(errno)); } return PCAP_ERROR; } } /* * Note that we have to put the old mode back when we * close the device. */ handlep->must_do_on_close |= MUST_CLEAR_RFMON; /* * Add this to the list of pcaps to close when we exit. */ pcap_add_to_pcaps_to_close(handle); return 1; } #endif /* IW_MODE_MONITOR */ /* * Try various mechanisms to enter monitor mode. */ static int enter_rfmon_mode(pcap_t *handle, int sock_fd, const char *device) { #if defined(HAVE_LIBNL) || defined(IW_MODE_MONITOR) int ret; #endif #ifdef HAVE_LIBNL ret = enter_rfmon_mode_mac80211(handle, sock_fd, device); if (ret < 0) return ret; /* error attempting to do so */ if (ret == 1) return 1; /* success */ #endif /* HAVE_LIBNL */ #ifdef IW_MODE_MONITOR ret = enter_rfmon_mode_wext(handle, sock_fd, device); if (ret < 0) return ret; /* error attempting to do so */ if (ret == 1) return 1; /* success */ #endif /* IW_MODE_MONITOR */ /* * Either none of the mechanisms we know about work or none * of those mechanisms are available, so we can't do monitor * mode. */ return 0; } #if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) /* * Map SOF_TIMESTAMPING_ values to PCAP_TSTAMP_ values. */ static const struct { int soft_timestamping_val; int pcap_tstamp_val; } sof_ts_type_map[3] = { { SOF_TIMESTAMPING_SOFTWARE, PCAP_TSTAMP_HOST }, { SOF_TIMESTAMPING_SYS_HARDWARE, PCAP_TSTAMP_ADAPTER }, { SOF_TIMESTAMPING_RAW_HARDWARE, PCAP_TSTAMP_ADAPTER_UNSYNCED } }; #define NUM_SOF_TIMESTAMPING_TYPES (sizeof sof_ts_type_map / sizeof sof_ts_type_map[0]) #ifdef ETHTOOL_GET_TS_INFO /* * Get a list of time stamping capabilities. */ static int iface_ethtool_get_ts_info(pcap_t *handle, char *ebuf) { int fd; struct ifreq ifr; struct ethtool_ts_info info; int num_ts_types; int i, j; /* * Create a socket from which to fetch time stamping capabilities. */ fd = socket(AF_INET, SOCK_DGRAM, 0); if (fd < 0) { (void)snprintf(ebuf, PCAP_ERRBUF_SIZE, "socket for SIOCETHTOOL(ETHTOOL_GET_TS_INFO): %s", pcap_strerror(errno)); return -1; } memset(&ifr, 0, sizeof(ifr)); strlcpy(ifr.ifr_name, handle->opt.source, sizeof(ifr.ifr_name)); memset(&info, 0, sizeof(info)); info.cmd = ETHTOOL_GET_TS_INFO; ifr.ifr_data = (caddr_t)&info; if (ioctl(fd, SIOCETHTOOL, &ifr) == -1) { if (errno == EOPNOTSUPP || errno == EINVAL) { /* * OK, let's just return all the possible time * stamping types. */ return SOF_TIMESTAMPING_SOFTWARE|SOF_TIMESTAMPING_SYS_HARDWARE|SOF_TIMESTAMPING_RAW_HARDWARE; } snprintf(ebuf, PCAP_ERRBUF_SIZE, "%s: SIOETHTOOL(ETHTOOL_GET_TS_INFO) ioctl failed: %s", handle->opt.source, strerror(errno)); close(fd); return -1; } close(fd); num_ts_types = 0; for (i = 0; i < NUM_SOF_TIMESTAMPING_TYPES; i++) { if (info.so_timestamping & sof_ts_type_map[i].soft_timestamping_val) num_ts_types++; } handle->tstamp_type_count = num_ts_types; if (num_ts_types != 0) { handle->tstamp_type_list = malloc(num_ts_types * sizeof(u_int)); for (i = 0, j = 0; i < NUM_SOF_TIMESTAMPING_TYPES; i++) { if (info.so_timestamping & sof_ts_type_map[i].soft_timestamping_val) { handle->tstamp_type_list[j] = sof_ts_type_map[i].pcap_tstamp_val; j++; } } } else handle->tstamp_type_list = NULL; return 0; } #else /* ETHTOOL_GET_TS_INFO */ static int iface_ethtool_get_ts_info(pcap_t *handle, char *ebuf _U_) { int i; /* * We don't have an ioctl to use to ask what's supported, * so say we support everything. */ handle->tstamp_type_count = NUM_SOF_TIMESTAMPING_TYPES; handle->tstamp_type_list = malloc(NUM_SOF_TIMESTAMPING_TYPES * sizeof(u_int)); for (i = 0; i < NUM_SOF_TIMESTAMPING_TYPES; i++) handle->tstamp_type_list[i] = sof_ts_type_map[i].pcap_tstamp_val; return 0; } #endif /* ETHTOOL_GET_TS_INFO */ #endif /* defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) */ /* * Find out if we have any form of fragmentation/reassembly offloading. * * We do so using SIOCETHTOOL checking for various types of offloading; * if SIOCETHTOOL isn't defined, or we don't have any #defines for any * of the types of offloading, there's nothing we can do to check, so * we just say "no, we don't". */ #if defined(SIOCETHTOOL) && (defined(ETHTOOL_GTSO) || defined(ETHTOOL_GUFO) || defined(ETHTOOL_GGSO) || defined(ETHTOOL_GFLAGS) || defined(ETHTOOL_GGRO)) static int iface_ethtool_flag_ioctl(pcap_t *handle, int cmd, const char *cmdname) { struct ifreq ifr; struct ethtool_value eval; memset(&ifr, 0, sizeof(ifr)); strlcpy(ifr.ifr_name, handle->opt.source, sizeof(ifr.ifr_name)); eval.cmd = cmd; eval.data = 0; ifr.ifr_data = (caddr_t)&eval; if (ioctl(handle->fd, SIOCETHTOOL, &ifr) == -1) { if (errno == EOPNOTSUPP || errno == EINVAL) { /* * OK, let's just return 0, which, in our * case, either means "no, what we're asking * about is not enabled" or "all the flags * are clear (i.e., nothing is enabled)". */ return 0; } snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "%s: SIOETHTOOL(%s) ioctl failed: %s", handle->opt.source, cmdname, strerror(errno)); return -1; } return eval.data; } static int iface_get_offload(pcap_t *handle) { int ret; #ifdef ETHTOOL_GTSO ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GTSO, "ETHTOOL_GTSO"); if (ret == -1) return -1; if (ret) return 1; /* TCP segmentation offloading on */ #endif #ifdef ETHTOOL_GUFO ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GUFO, "ETHTOOL_GUFO"); if (ret == -1) return -1; if (ret) return 1; /* UDP fragmentation offloading on */ #endif #ifdef ETHTOOL_GGSO /* * XXX - will this cause large unsegmented packets to be * handed to PF_PACKET sockets on transmission? If not, * this need not be checked. */ ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GGSO, "ETHTOOL_GGSO"); if (ret == -1) return -1; if (ret) return 1; /* generic segmentation offloading on */ #endif #ifdef ETHTOOL_GFLAGS ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GFLAGS, "ETHTOOL_GFLAGS"); if (ret == -1) return -1; if (ret & ETH_FLAG_LRO) return 1; /* large receive offloading on */ #endif #ifdef ETHTOOL_GGRO /* * XXX - will this cause large reassembled packets to be * handed to PF_PACKET sockets on receipt? If not, * this need not be checked. */ ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GGRO, "ETHTOOL_GGRO"); if (ret == -1) return -1; if (ret) return 1; /* generic (large) receive offloading on */ #endif return 0; } #else /* SIOCETHTOOL */ static int iface_get_offload(pcap_t *handle _U_) { /* * XXX - do we need to get this information if we don't * have the ethtool ioctls? If so, how do we do that? */ return 0; } #endif /* SIOCETHTOOL */ #endif /* HAVE_PF_PACKET_SOCKETS */ /* ===== Functions to interface to the older kernels ================== */ /* * Try to open a packet socket using the old kernel interface. * Returns 1 on success and a PCAP_ERROR_ value on an error. */ static int activate_old(pcap_t *handle) { struct pcap_linux *handlep = handle->priv; int arptype; struct ifreq ifr; const char *device = handle->opt.source; struct utsname utsname; int mtu; /* Open the socket */ handle->fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL)); if (handle->fd == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "socket: %s", pcap_strerror(errno)); if (errno == EPERM || errno == EACCES) { /* * You don't have permission to open the * socket. */ return PCAP_ERROR_PERM_DENIED; } else { /* * Other error. */ return PCAP_ERROR; } } /* It worked - we are using the old interface */ handlep->sock_packet = 1; /* ...which means we get the link-layer header. */ handlep->cooked = 0; /* Bind to the given device */ if (strcmp(device, "any") == 0) { strlcpy(handle->errbuf, "pcap_activate: The \"any\" device isn't supported on 2.0[.x]-kernel systems", PCAP_ERRBUF_SIZE); return PCAP_ERROR; } if (iface_bind_old(handle->fd, device, handle->errbuf) == -1) return PCAP_ERROR; /* * Try to get the link-layer type. */ arptype = iface_get_arptype(handle->fd, device, handle->errbuf); if (arptype < 0) return PCAP_ERROR; /* * Try to find the DLT_ type corresponding to that * link-layer type. */ map_arphrd_to_dlt(handle, arptype, device, 0); if (handle->linktype == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "unknown arptype %d", arptype); return PCAP_ERROR; } /* Go to promisc mode if requested */ if (handle->opt.promisc) { memset(&ifr, 0, sizeof(ifr)); strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SIOCGIFFLAGS: %s", pcap_strerror(errno)); return PCAP_ERROR; } if ((ifr.ifr_flags & IFF_PROMISC) == 0) { /* * Promiscuous mode isn't currently on, * so turn it on, and remember that * we should turn it off when the * pcap_t is closed. */ /* * If we haven't already done so, arrange * to have "pcap_close_all()" called when * we exit. */ if (!pcap_do_addexit(handle)) { /* * "atexit()" failed; don't put * the interface in promiscuous * mode, just give up. */ return PCAP_ERROR; } ifr.ifr_flags |= IFF_PROMISC; if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "SIOCSIFFLAGS: %s", pcap_strerror(errno)); return PCAP_ERROR; } handlep->must_do_on_close |= MUST_CLEAR_PROMISC; /* * Add this to the list of pcaps * to close when we exit. */ pcap_add_to_pcaps_to_close(handle); } } /* * Compute the buffer size. * * We're using SOCK_PACKET, so this might be a 2.0[.x] * kernel, and might require special handling - check. */ if (uname(&utsname) < 0 || strncmp(utsname.release, "2.0", 3) == 0) { /* * Either we couldn't find out what kernel release * this is, or it's a 2.0[.x] kernel. * * In the 2.0[.x] kernel, a "recvfrom()" on * a SOCK_PACKET socket, with MSG_TRUNC set, will * return the number of bytes read, so if we pass * a length based on the snapshot length, it'll * return the number of bytes from the packet * copied to userland, not the actual length * of the packet. * * This means that, for example, the IP dissector * in tcpdump will get handed a packet length less * than the length in the IP header, and will * complain about "truncated-ip". * * So we don't bother trying to copy from the * kernel only the bytes in which we're interested, * but instead copy them all, just as the older * versions of libpcap for Linux did. * * The buffer therefore needs to be big enough to * hold the largest packet we can get from this * device. Unfortunately, we can't get the MRU * of the network; we can only get the MTU. The * MTU may be too small, in which case a packet larger * than the buffer size will be truncated *and* we * won't get the actual packet size. * * However, if the snapshot length is larger than * the buffer size based on the MTU, we use the * snapshot length as the buffer size, instead; * this means that with a sufficiently large snapshot * length we won't artificially truncate packets * to the MTU-based size. * * This mess just one of many problems with packet * capture on 2.0[.x] kernels; you really want a * 2.2[.x] or later kernel if you want packet capture * to work well. */ mtu = iface_get_mtu(handle->fd, device, handle->errbuf); if (mtu == -1) return PCAP_ERROR; handle->bufsize = MAX_LINKHEADER_SIZE + mtu; if (handle->bufsize < handle->snapshot) handle->bufsize = handle->snapshot; } else { /* * This is a 2.2[.x] or later kernel. * * We can safely pass "recvfrom()" a byte count * based on the snapshot length. */ handle->bufsize = handle->snapshot; } /* * Default value for offset to align link-layer payload * on a 4-byte boundary. */ handle->offset = 0; /* * SOCK_PACKET sockets don't supply information from * stripped VLAN tags. */ handlep->vlan_offset = -1; /* unknown */ return 1; } /* * Bind the socket associated with FD to the given device using the * interface of the old kernels. */ static int iface_bind_old(int fd, const char *device, char *ebuf) { struct sockaddr saddr; int err; socklen_t errlen = sizeof(err); memset(&saddr, 0, sizeof(saddr)); strlcpy(saddr.sa_data, device, sizeof(saddr.sa_data)); if (bind(fd, &saddr, sizeof(saddr)) == -1) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "bind: %s", pcap_strerror(errno)); return -1; } /* Any pending errors, e.g., network is down? */ if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "getsockopt: %s", pcap_strerror(errno)); return -1; } if (err > 0) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "bind: %s", pcap_strerror(err)); return -1; } return 0; } /* ===== System calls available on all supported kernels ============== */ /* * Query the kernel for the MTU of the given interface. */ static int iface_get_mtu(int fd, const char *device, char *ebuf) { struct ifreq ifr; if (!device) return BIGGER_THAN_ALL_MTUS; memset(&ifr, 0, sizeof(ifr)); strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); if (ioctl(fd, SIOCGIFMTU, &ifr) == -1) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "SIOCGIFMTU: %s", pcap_strerror(errno)); return -1; } return ifr.ifr_mtu; } /* * Get the hardware type of the given interface as ARPHRD_xxx constant. */ static int iface_get_arptype(int fd, const char *device, char *ebuf) { struct ifreq ifr; memset(&ifr, 0, sizeof(ifr)); strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); if (ioctl(fd, SIOCGIFHWADDR, &ifr) == -1) { snprintf(ebuf, PCAP_ERRBUF_SIZE, "SIOCGIFHWADDR: %s", pcap_strerror(errno)); if (errno == ENODEV) { /* * No such device. */ return PCAP_ERROR_NO_SUCH_DEVICE; } return PCAP_ERROR; } return ifr.ifr_hwaddr.sa_family; } #ifdef SO_ATTACH_FILTER static int fix_program(pcap_t *handle, struct sock_fprog *fcode, int is_mmapped) { struct pcap_linux *handlep = handle->priv; size_t prog_size; register int i; register struct bpf_insn *p; struct bpf_insn *f; int len; /* * Make a copy of the filter, and modify that copy if * necessary. */ prog_size = sizeof(*handle->fcode.bf_insns) * handle->fcode.bf_len; len = handle->fcode.bf_len; f = (struct bpf_insn *)malloc(prog_size); if (f == NULL) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "malloc: %s", pcap_strerror(errno)); return -1; } memcpy(f, handle->fcode.bf_insns, prog_size); fcode->len = len; fcode->filter = (struct sock_filter *) f; for (i = 0; i < len; ++i) { p = &f[i]; /* * What type of instruction is this? */ switch (BPF_CLASS(p->code)) { case BPF_RET: /* * It's a return instruction; are we capturing * in memory-mapped mode? */ if (!is_mmapped) { /* * No; is the snapshot length a constant, * rather than the contents of the * accumulator? */ if (BPF_MODE(p->code) == BPF_K) { /* * Yes - if the value to be returned, * i.e. the snapshot length, is * anything other than 0, make it * MAXIMUM_SNAPLEN, so that the packet * is truncated by "recvfrom()", * not by the filter. * * XXX - there's nothing we can * easily do if it's getting the * value from the accumulator; we'd * have to insert code to force * non-zero values to be * MAXIMUM_SNAPLEN. */ if (p->k != 0) p->k = MAXIMUM_SNAPLEN; } } break; case BPF_LD: case BPF_LDX: /* * It's a load instruction; is it loading * from the packet? */ switch (BPF_MODE(p->code)) { case BPF_ABS: case BPF_IND: case BPF_MSH: /* * Yes; are we in cooked mode? */ if (handlep->cooked) { /* * Yes, so we need to fix this * instruction. */ if (fix_offset(p) < 0) { /* * We failed to do so. * Return 0, so our caller * knows to punt to userland. */ return 0; } } break; } break; } } return 1; /* we succeeded */ } static int fix_offset(struct bpf_insn *p) { /* * What's the offset? */ if (p->k >= SLL_HDR_LEN) { /* * It's within the link-layer payload; that starts at an * offset of 0, as far as the kernel packet filter is * concerned, so subtract the length of the link-layer * header. */ p->k -= SLL_HDR_LEN; } else if (p->k == 0) { /* * It's the packet type field; map it to the special magic * kernel offset for that field. */ p->k = SKF_AD_OFF + SKF_AD_PKTTYPE; } else if (p->k == 14) { /* * It's the protocol field; map it to the special magic * kernel offset for that field. */ p->k = SKF_AD_OFF + SKF_AD_PROTOCOL; } else if ((bpf_int32)(p->k) > 0) { /* * It's within the header, but it's not one of those * fields; we can't do that in the kernel, so punt * to userland. */ return -1; } return 0; } static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode) { int total_filter_on = 0; int save_mode; int ret; int save_errno; /* * The socket filter code doesn't discard all packets queued * up on the socket when the filter is changed; this means * that packets that don't match the new filter may show up * after the new filter is put onto the socket, if those * packets haven't yet been read. * * This means, for example, that if you do a tcpdump capture * with a filter, the first few packets in the capture might * be packets that wouldn't have passed the filter. * * We therefore discard all packets queued up on the socket * when setting a kernel filter. (This isn't an issue for * userland filters, as the userland filtering is done after * packets are queued up.) * * To flush those packets, we put the socket in read-only mode, * and read packets from the socket until there are no more to * read. * * In order to keep that from being an infinite loop - i.e., * to keep more packets from arriving while we're draining * the queue - we put the "total filter", which is a filter * that rejects all packets, onto the socket before draining * the queue. * * This code deliberately ignores any errors, so that you may * get bogus packets if an error occurs, rather than having * the filtering done in userland even if it could have been * done in the kernel. */ if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER, &total_fcode, sizeof(total_fcode)) == 0) { char drain[1]; /* * Note that we've put the total filter onto the socket. */ total_filter_on = 1; /* * Save the socket's current mode, and put it in * non-blocking mode; we drain it by reading packets * until we get an error (which is normally a * "nothing more to be read" error). */ save_mode = fcntl(handle->fd, F_GETFL, 0); if (save_mode == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't get FD flags when changing filter: %s", pcap_strerror(errno)); return -2; } if (fcntl(handle->fd, F_SETFL, save_mode | O_NONBLOCK) < 0) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't set nonblocking mode when changing filter: %s", pcap_strerror(errno)); return -2; } while (recv(handle->fd, &drain, sizeof drain, MSG_TRUNC) >= 0) ; save_errno = errno; if (save_errno != EAGAIN) { /* * Fatal error. * * If we can't restore the mode or reset the * kernel filter, there's nothing we can do. */ (void)fcntl(handle->fd, F_SETFL, save_mode); (void)reset_kernel_filter(handle); snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "recv failed when changing filter: %s", pcap_strerror(save_errno)); return -2; } if (fcntl(handle->fd, F_SETFL, save_mode) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't restore FD flags when changing filter: %s", pcap_strerror(save_errno)); return -2; } } /* * Now attach the new filter. */ ret = setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER, fcode, sizeof(*fcode)); if (ret == -1 && total_filter_on) { /* * Well, we couldn't set that filter on the socket, * but we could set the total filter on the socket. * * This could, for example, mean that the filter was * too big to put into the kernel, so we'll have to * filter in userland; in any case, we'll be doing * filtering in userland, so we need to remove the * total filter so we see packets. */ save_errno = errno; /* * If this fails, we're really screwed; we have the * total filter on the socket, and it won't come off. * Report it as a fatal error. */ if (reset_kernel_filter(handle) == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "can't remove kernel total filter: %s", pcap_strerror(errno)); return -2; /* fatal error */ } errno = save_errno; } return ret; } static int reset_kernel_filter(pcap_t *handle) { /* * setsockopt() barfs unless it get a dummy parameter. * valgrind whines unless the value is initialized, * as it has no idea that setsockopt() ignores its * parameter. */ int dummy = 0; return setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER, &dummy, sizeof(dummy)); } #endif