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libpcap-1.10.2
pcap-linux.c
5 587 строк
155 KB
Bill Fenner
Close the eventfd if we are non-blocking
28 авг 2022, 03:40
28 авг 2022, 03:40
3b26eab
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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. */ #define _GNU_SOURCE #ifdef HAVE_CONFIG_H #include <config.h> #endif #include <errno.h> #include <stdio.h> #include <stdlib.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 <linux/ethtool.h> #include <netinet/in.h> #include <linux/if_ether.h> #include <linux/if_arp.h> #include <poll.h> #include <dirent.h> #include <sys/eventfd.h> #include "pcap-int.h" #include "pcap/sll.h" #include "pcap/vlan.h" #include "pcap/can_socketcan.h" #include "diag-control.h" /* * We require TPACKET_V2 support. */ #ifndef TPACKET2_HDRLEN #error "Libpcap will only work if TPACKET_V2 is supported; you must build for a 2.6.27 or later kernel" #endif /* 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 TPACKET3_HDRLEN # define HAVE_TPACKET3 #endif /* TPACKET3_HDRLEN */ /* * Not all compilers that are used to compile code to run on Linux have * these builtins. For example, older versions of GCC don't, and at * least some people are doing cross-builds for MIPS with older versions * of GCC. */ #ifndef HAVE___ATOMIC_LOAD_N #define __atomic_load_n(ptr, memory_model) (*(ptr)) #endif #ifndef HAVE___ATOMIC_STORE_N #define __atomic_store_n(ptr, val, memory_model) *(ptr) = (val) #endif #define packet_mmap_acquire(pkt) \ (__atomic_load_n(&pkt->tp_status, __ATOMIC_ACQUIRE) != TP_STATUS_KERNEL) #define packet_mmap_release(pkt) \ (__atomic_store_n(&pkt->tp_status, TP_STATUS_KERNEL, __ATOMIC_RELEASE)) #define packet_mmap_v3_acquire(pkt) \ (__atomic_load_n(&pkt->hdr.bh1.block_status, __ATOMIC_ACQUIRE) != TP_STATUS_KERNEL) #define packet_mmap_v3_release(pkt) \ (__atomic_store_n(&pkt->hdr.bh1.block_status, TP_STATUS_KERNEL, __ATOMIC_RELEASE)) #include <linux/types.h> #include <linux/filter.h> #ifdef HAVE_LINUX_NET_TSTAMP_H #include <linux/net_tstamp.h> #endif /* * For checking whether a device is a bonding device. */ #include <linux/if_bonding.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 */ #ifndef HAVE_SOCKLEN_T typedef int socklen_t; #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 PF_PACKET sockets. */ struct pcap_linux { long long sysfs_dropped; /* packets reported dropped by /sys/class/net/{if_name}/statistics/rx_{missed,fifo}_errors */ 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 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 */ int netdown; /* we got an ENETDOWN and haven't resolved it */ 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 */ int poll_timeout; /* timeout to use in poll() */ #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 int poll_breakloop_fd; /* fd to an eventfd to break from blocking operations */ }; /* * Stuff to do when we close. */ #define MUST_CLEAR_RFMON 0x00000001 /* clear rfmon (monitor) mode */ #define MUST_DELETE_MONIF 0x00000002 /* delete monitor-mode interface */ /* * Prototypes for internal functions and methods. */ static int get_if_flags(const char *, bpf_u_int32 *, char *); static int is_wifi(const char *); static void map_arphrd_to_dlt(pcap_t *, int, const char *, int); static int pcap_activate_linux(pcap_t *); static int setup_socket(pcap_t *, int); static int setup_mmapped(pcap_t *, int *); static int pcap_can_set_rfmon_linux(pcap_t *); static int pcap_inject_linux(pcap_t *, const void *, int); 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 tpacket2_hdr *h2; #ifdef HAVE_TPACKET3 struct tpacket_block_desc *h3; #endif u_char *raw; }; #define RING_GET_FRAME_AT(h, offset) (((u_char **)h->buffer)[(offset)]) #define RING_GET_CURRENT_FRAME(h) RING_GET_FRAME_AT(h, 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 int pcap_read_linux_mmap_v2(pcap_t *, int, pcap_handler , u_char *); #ifdef HAVE_TPACKET3 static int pcap_read_linux_mmap_v3(pcap_t *, int, pcap_handler , u_char *); #endif static int pcap_setnonblock_linux(pcap_t *p, int nonblock); static int pcap_getnonblock_linux(pcap_t *p); static void pcap_oneshot_linux(u_char *user, const struct pcap_pkthdr *h, const u_char *bytes); /* * In pre-3.0 kernels, the tp_vlan_tci field is set to whatever the * vlan_tci field in the skbuff is. 0 can either mean "not on a VLAN" * or "on VLAN 0". There is no flag set in the tp_status field to * distinguish between them. * * In 3.0 and later kernels, if there's a VLAN tag present, the tp_vlan_tci * field is set to the VLAN tag, and the TP_STATUS_VLAN_VALID flag is set * in the tp_status field, otherwise the tp_vlan_tci field is set to 0 and * the TP_STATUS_VLAN_VALID flag isn't set in the tp_status field. * * With a pre-3.0 kernel, we cannot distinguish between packets with no * VLAN tag and packets on VLAN 0, so we will mishandle some packets, and * there's nothing we can do about that. * * So, on those systems, which never set the TP_STATUS_VLAN_VALID flag, we * continue the behavior of earlier libpcaps, wherein we treated packets * with a VLAN tag of 0 as being packets without a VLAN tag rather than packets * on VLAN 0. We do this by treating packets with a tp_vlan_tci of 0 and * with the TP_STATUS_VLAN_VALID flag not set in tp_status as not having * VLAN tags. This does the right thing on 3.0 and later kernels, and * continues the old unfixably-imperfect behavior on pre-3.0 kernels. * * If TP_STATUS_VLAN_VALID isn't defined, we test it as the 0x10 bit; it * has that value in 3.0 and later kernels. */ #ifdef TP_STATUS_VLAN_VALID #define VLAN_VALID(hdr, hv) ((hv)->tp_vlan_tci != 0 || ((hdr)->tp_status & TP_STATUS_VLAN_VALID)) #else /* * This is being compiled on a system that lacks TP_STATUS_VLAN_VALID, * so we testwith the value it has in the 3.0 and later kernels, so * we can test it if we're running on a system that has it. (If we're * running on a system that doesn't have it, it won't be set in the * tp_status field, so the tests of it will always fail; that means * we behave the way we did before we introduced this macro.) */ #define VLAN_VALID(hdr, hv) ((hv)->tp_vlan_tci != 0 || ((hdr)->tp_status & 0x10)) #endif #ifdef TP_STATUS_VLAN_TPID_VALID # define VLAN_TPID(hdr, hv) (((hv)->tp_vlan_tpid || ((hdr)->tp_status & TP_STATUS_VLAN_TPID_VALID)) ? (hv)->tp_vlan_tpid : ETH_P_8021Q) #else # define VLAN_TPID(hdr, hv) ETH_P_8021Q #endif /* * Required select timeout if we're polling for an "interface disappeared" * indication - 1 millisecond. */ static const struct timeval netdown_timeout = { 0, 1000 /* 1000 microseconds = 1 millisecond */ }; /* * Wrap some ioctl calls */ static int iface_get_id(int fd, const char *device, char *ebuf); static int iface_get_mtu(int fd, const char *device, char *ebuf); static int iface_get_arptype(int fd, const char *device, char *ebuf); static int iface_bind(int fd, int ifindex, char *ebuf, int protocol); static int enter_rfmon_mode(pcap_t *handle, int sock_fd, const char *device); static int iface_get_ts_types(const char *device, pcap_t *handle, char *ebuf); static int iface_get_offload(pcap_t *handle); static int fix_program(pcap_t *handle, struct sock_fprog *fcode); static int fix_offset(pcap_t *handle, 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 }; static int iface_dsa_get_proto_info(const char *device, pcap_t *handle); pcap_t * pcap_create_interface(const char *device, char *ebuf) { pcap_t *handle; handle = PCAP_CREATE_COMMON(ebuf, struct pcap_linux); if (handle == NULL) return NULL; handle->activate_op = pcap_activate_linux; handle->can_set_rfmon_op = pcap_can_set_rfmon_linux; /* * See what time stamp types we support. */ if (iface_get_ts_types(device, handle, ebuf) == -1) { pcap_close(handle); return NULL; } /* * 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_list = malloc(2 * sizeof(u_int)); if (handle->tstamp_precision_list == NULL) { pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, errno, "malloc"); pcap_close(handle); return NULL; } handle->tstamp_precision_list[0] = PCAP_TSTAMP_PRECISION_MICRO; handle->tstamp_precision_list[1] = PCAP_TSTAMP_PRECISION_NANO; handle->tstamp_precision_count = 2; struct pcap_linux *handlep = handle->priv; handlep->poll_breakloop_fd = eventfd(0, EFD_NONBLOCK); return handle; } #ifdef HAVE_LIBNL /* * If interface {if_name} is a mac80211 driver, the file * /sys/class/net/{if_name}/phy80211 is a symlink to * /sys/class/ieee80211/{phydev_name}, for some {phydev_name}. * * 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_name} interface add {monif_name} type monitor * * where {monif_name} is the monitor device. It then (sigh) sleeps * .1 second, and then configures the device up. Otherwise, if * /sys/class/ieee80211/{phydev_name}/add_iface is a file, it writes * {mondev_name}, 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/{if_name}/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_name} interface del * * or by sending {monif_name}, with no NL, down * /sys/class/ieee80211/{phydev_name}/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; } pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "%s: Can't readlink %s", device, pathstr); free(pathstr); return PCAP_ERROR; } free(pathstr); phydev_path[bytes_read] = '\0'; return 1; } 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, nl_geterror(-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 del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, const char *device, const char *mondevice); static int add_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state, const char *device, const char *mondevice) { struct pcap_linux *handlep = handle->priv; 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); DIAG_OFF_NARROWING NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, mondevice); DIAG_ON_NARROWING NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR); err = nl_send_auto_complete(state->nl_sock, msg); if (err < 0) { if (err == -NLE_FAILURE) { /* * 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, nl_geterror(-err)); nlmsg_free(msg); return PCAP_ERROR; } } err = nl_wait_for_ack(state->nl_sock); if (err < 0) { if (err == -NLE_FAILURE) { /* * 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, nl_geterror(-err)); nlmsg_free(msg); return PCAP_ERROR; } } /* * Success. */ nlmsg_free(msg); /* * Try to remember the monitor device. */ handlep->mondevice = strdup(mondevice); if (handlep->mondevice == NULL) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "strdup"); /* * Get rid of the monitor device. */ del_mon_if(handle, sock_fd, state, device, mondevice); return PCAP_ERROR; } 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, nl_geterror(-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, nl_geterror(-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; } #endif /* HAVE_LIBNL */ static int pcap_protocol(pcap_t *handle) { int protocol; protocol = handle->opt.protocol; if (protocol == 0) protocol = ETH_P_ALL; return htons(protocol); } static int pcap_can_set_rfmon_linux(pcap_t *handle) { #ifdef HAVE_LIBNL char phydev_path[PATH_MAX+1]; int ret; #endif if (strcmp(handle->opt.device, "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. */ ret = get_mac80211_phydev(handle, handle->opt.device, phydev_path, PATH_MAX); if (ret < 0) return ret; /* error */ if (ret == 1) return 1; /* mac80211 device */ #endif return 0; } /* * Grabs the number of missed packets by the interface from * /sys/class/net/{if_name}/statistics/rx_{missed,fifo}_errors. * * Compared to /proc/net/dev this avoids counting software drops, * but may be unimplemented and just return 0. * The author has found no straigthforward way to check for support. */ static long long int linux_get_stat(const char * if_name, const char * stat) { ssize_t bytes_read; int fd; char buffer[PATH_MAX]; snprintf(buffer, sizeof(buffer), "/sys/class/net/%s/statistics/%s", if_name, stat); fd = open(buffer, O_RDONLY); if (fd == -1) return 0; bytes_read = read(fd, buffer, sizeof(buffer) - 1); close(fd); if (bytes_read == -1) return 0; buffer[bytes_read] = '\0'; return strtoll(buffer, NULL, 10); } static long long int linux_if_drops(const char * if_name) { long long int missed = linux_get_stat(if_name, "rx_missed_errors"); long long int fifo = linux_get_stat(if_name, "rx_fifo_errors"); return missed + fifo; } /* * Monitor 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 monitor 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 monitor * mode. */ static void pcap_cleanup_linux( pcap_t *handle ) { struct pcap_linux *handlep = handle->priv; #ifdef HAVE_LIBNL struct nl80211_state nlstate; int ret; #endif /* HAVE_LIBNL */ if (handlep->must_do_on_close != 0) { /* * There's something we have to do when closing this * pcap_t. */ #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 */ /* * 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 (handle->fd != -1) { /* * Destroy the ring buffer (assuming we've set it up), * and unmap it if it's mapped. */ destroy_ring(handle); } if (handlep->oneshot_buffer != NULL) { free(handlep->oneshot_buffer); handlep->oneshot_buffer = NULL; } if (handlep->mondevice != NULL) { free(handlep->mondevice); handlep->mondevice = NULL; } if (handlep->device != NULL) { free(handlep->device); handlep->device = NULL; } if (handlep->poll_breakloop_fd != -1) { close(handlep->poll_breakloop_fd); handlep->poll_breakloop_fd = -1; } pcap_cleanup_live_common(handle); } #ifdef HAVE_TPACKET3 /* * Some versions of TPACKET_V3 have annoying bugs/misfeatures * around which we have to work. Determine if we have those * problems or not. * 3.19 is the first release with a fixed version of * TPACKET_V3. We treat anything before that as * not having a fixed version; that may really mean * it has *no* version. */ static int has_broken_tpacket_v3(void) { struct utsname utsname; const char *release; long major, minor; int matches, verlen; /* No version information, assume broken. */ if (uname(&utsname) == -1) return 1; release = utsname.release; /* A malformed version, ditto. */ matches = sscanf(release, "%ld.%ld%n", &major, &minor, &verlen); if (matches != 2) return 1; if (release[verlen] != '.' && release[verlen] != '\0') return 1; /* OK, a fixed version. */ if (major > 3 || (major == 3 && minor >= 19)) return 0; /* Too old :( */ return 1; } #endif /* * Set the timeout to be used in poll() with memory-mapped packet capture. */ static void set_poll_timeout(struct pcap_linux *handlep) { #ifdef HAVE_TPACKET3 int broken_tpacket_v3 = has_broken_tpacket_v3(); #endif if (handlep->timeout == 0) { #ifdef HAVE_TPACKET3 /* * XXX - due to a set of (mis)features in the TPACKET_V3 * kernel code prior to the 3.19 kernel, 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 (handlep->tp_version == TPACKET_V3 && broken_tpacket_v3) handlep->poll_timeout = 1; /* don't block for very long */ else #endif handlep->poll_timeout = -1; /* block forever */ } else if (handlep->timeout > 0) { #ifdef HAVE_TPACKET3 /* * For TPACKET_V3, the timeout is handled by the kernel, * so block forever; that way, we don't get extra timeouts. * Don't do that if we have a broken TPACKET_V3, though. */ if (handlep->tp_version == TPACKET_V3 && !broken_tpacket_v3) handlep->poll_timeout = -1; /* block forever, let TPACKET_V3 wake us up */ else #endif handlep->poll_timeout = handlep->timeout; /* block for that amount of time */ } else { /* * Non-blocking mode; we call poll() to pick up error * indications, but we don't want it to wait for * anything. */ handlep->poll_timeout = 0; } } static void pcap_breakloop_linux(pcap_t *handle) { pcap_breakloop_common(handle); struct pcap_linux *handlep = handle->priv; uint64_t value = 1; /* XXX - what if this fails? */ if (handlep->poll_breakloop_fd != -1) (void)write(handlep->poll_breakloop_fd, &value, sizeof(value)); } /* * Set the offset at which to insert VLAN tags. * That should be the offset of the type field. */ static void set_vlan_offset(pcap_t *handle) { struct pcap_linux *handlep = handle->priv; switch (handle->linktype) { case DLT_EN10MB: /* * The type field is after the destination and source * MAC address. */ handlep->vlan_offset = 2 * ETH_ALEN; break; case DLT_LINUX_SLL: /* * The type field is in the last 2 bytes of the * DLT_LINUX_SLL header. */ handlep->vlan_offset = SLL_HDR_LEN - 2; break; default: handlep->vlan_offset = -1; /* unknown */ break; } } /* * 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 promiscuous 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; int is_any_device; struct ifreq ifr; int status = 0; int status2 = 0; int ret; device = handle->opt.device; /* * 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)) { /* * There's nothing more to say, so clear the error * message. */ handle->errbuf[0] = '\0'; status = PCAP_ERROR_NO_SUCH_DEVICE; goto fail; } /* * Turn a negative snapshot value (invalid), a snapshot value of * 0 (unspecified), or a value bigger than the normal maximum * value, into the maximum allowed value. * * If some application really *needs* a bigger snapshot * length, we should just increase MAXIMUM_SNAPLEN. */ if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN) handle->snapshot = MAXIMUM_SNAPLEN; handlep->device = strdup(device); if (handlep->device == NULL) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "strdup"); status = PCAP_ERROR; goto fail; } /* * The "any" device is a special device which causes us not * to bind to a particular device and thus to look at all * devices. */ is_any_device = (strcmp(device, "any") == 0); if (is_any_device) { 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; } } /* 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 * /sys/class/net/{if_name}/statistics/rx_{missed,fifo}_errors */ if (handle->opt.promisc) handlep->sysfs_dropped = linux_if_drops(handlep->device); /* * If the "any" device is specified, try to open a SOCK_DGRAM. * Otherwise, open a SOCK_RAW. */ ret = setup_socket(handle, is_any_device); if (ret < 0) { /* * Fatal error; the return value is the error code, * and handle->errbuf has been set to an appropriate * error message. */ status = ret; goto fail; } /* * Success. * Try to set up memory-mapped access. */ ret = setup_mmapped(handle, &status); if (ret == -1) { /* * We failed to set up to use it, or the * kernel supports it, but we failed to * enable it. status has been set to the * error status to return and, if it's * PCAP_ERROR, handle->errbuf contains * the error message. */ goto fail; } /* * We succeeded. status has been set to the status to return, * which might be 0, or might be a PCAP_WARNING_ value. */ /* * Now that we have activated the mmap ring, we can * set the correct protocol. */ if ((status2 = iface_bind(handle->fd, handlep->ifindex, handle->errbuf, pcap_protocol(handle))) != 0) { status = status2; 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->setnonblock_op = pcap_setnonblock_linux; handle->getnonblock_op = pcap_getnonblock_linux; handle->cleanup_op = pcap_cleanup_linux; handle->stats_op = pcap_stats_linux; handle->breakloop_op = pcap_breakloop_linux; switch (handlep->tp_version) { case TPACKET_V2: handle->read_op = pcap_read_linux_mmap_v2; break; #ifdef HAVE_TPACKET3 case TPACKET_V3: handle->read_op = pcap_read_linux_mmap_v3; break; #endif } handle->oneshot_callback = pcap_oneshot_linux; handle->selectable_fd = handle->fd; return status; fail: pcap_cleanup_linux(handle); return status; } static int pcap_set_datalink_linux(pcap_t *handle, int dlt) { handle->linktype = dlt; /* * Update the offset at which to insert VLAN tags for the * new link-layer type. */ set_vlan_offset(handle); 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 this is an outgoing CAN or CAN FD frame, and * the user doesn't only want outgoing packets, * reject it; CAN devices and drivers, and the CAN * stack, always arrange to loop back transmitted * packets, so they also appear as incoming packets. * We don't want duplicate packets, and we can't * easily distinguish packets looped back by the CAN * layer than those received by the CAN layer, so we * eliminate this packet instead. * * We check whether this is a CAN or CAN FD frame * by checking whether the device's hardware type * is ARPHRD_CAN. */ if (sll->sll_hatype == ARPHRD_CAN && handle->direction != PCAP_D_OUT) 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; } /* * Check whether the device to which the pcap_t is bound still exists. * We do so by asking what address the socket is bound to, and checking * whether the ifindex in the address is -1, meaning "that device is gone", * or some other value, meaning "that device still exists". */ static int device_still_exists(pcap_t *handle) { struct pcap_linux *handlep = handle->priv; struct sockaddr_ll addr; socklen_t addr_len; /* * If handlep->ifindex is -1, the socket isn't bound, meaning * we're capturing on the "any" device; that device never * disappears. (It should also never be configured down, so * we shouldn't even get here, but let's make sure.) */ if (handlep->ifindex == -1) return (1); /* it's still here */ /* * OK, now try to get the address for the socket. */ addr_len = sizeof (addr); if (getsockname(handle->fd, (struct sockaddr *) &addr, &addr_len) == -1) { /* * Error - report an error and return -1. */ pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "getsockname failed"); return (-1); } if (addr.sll_ifindex == -1) { /* * This means the device went away. */ return (0); } /* * The device presumably just went down. */ return (1); } static int pcap_inject_linux(pcap_t *handle, const void *buf, int size) { struct pcap_linux *handlep = handle->priv; int ret; if (handlep->ifindex == -1) { /* * We don't support sending on the "any" device. */ pcap_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 cooked-mode sockets. * * XXX - how do you send on a bound cooked-mode * socket? * Is a "sendto()" required there? */ pcap_strlcpy(handle->errbuf, "Sending packets isn't supported in cooked mode", PCAP_ERRBUF_SIZE); return (-1); } ret = (int)send(handle->fd, buf, size, 0); if (ret == -1) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "send"); return (-1); } return (ret); } /* * Get the statistics for the given packet capture handle. */ static int pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats) { struct pcap_linux *handlep = handle->priv; #ifdef HAVE_TPACKET3 /* * For sockets using 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); long long if_dropped = 0; /* * To fill in ps_ifdrop, we parse * /sys/class/net/{if_name}/statistics/rx_{missed,fifo}_errors * for the numbers */ if (handle->opt.promisc) { /* * XXX - is there any reason to do this by remembering * the last counts value, subtracting it from the * current counts value, and adding that to stat.ps_ifdrop, * maintaining stat.ps_ifdrop as a count, rather than just * saving the *initial* counts value and setting * stat.ps_ifdrop to the difference between the current * value and the initial value? * * One reason might be to handle the count wrapping * around, on platforms where the count is 32 bits * and where you might get more than 2^32 dropped * packets; is there any other reason? * * (We maintain the count as a long long int so that, * if the kernel maintains the counts as 64-bit even * on 32-bit platforms, we can handle the real count. * * Unfortunately, we can't report 64-bit counts; we * need a better API for reporting statistics, such as * one that reports them in a style similar to the * pcapng Interface Statistics Block, so that 1) the * counts are 64-bit, 2) it's easier to add new statistics * without breaking the ABI, and 3) it's easier to * indicate to a caller that wants one particular * statistic that it's not available by just not supplying * it.) */ if_dropped = handlep->sysfs_dropped; handlep->sysfs_dropped = linux_if_drops(handlep->device); handlep->stat.ps_ifdrop += (u_int)(handlep->sysfs_dropped - if_dropped); } /* * Try to get the packet counts from the kernel. */ if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, &kstats, &len) > -1) { /* * "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 2.6.27 * through 5.6 kernels, "tp_packets" is incremented for * every packet that passes the packet filter *and* is * successfully copied to the ring buffer; "tp_drops" is * incremented for every packet dropped because there's * not enough free space in the ring 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; } pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "failed to get statistics from socket"); return -1; } /* * Description string for the "any" device. */ static const char any_descr[] = "Pseudo-device that captures on all interfaces"; /* * A PF_PACKET socket can be bound to any network interface. */ static int can_be_bound(const char *name _U_) { return (1); } /* * Get a socket to use with various interface ioctls. */ static int get_if_ioctl_socket(void) { int fd; /* * This is a bit ugly. * * There isn't a socket type that's guaranteed to work. * * AF_NETLINK will work *if* you have Netlink configured into the * kernel (can it be configured out if you have any networking * support at all?) *and* if you're running a sufficiently recent * kernel, but not all the kernels we support are sufficiently * recent - that feature was introduced in Linux 4.6. * * AF_UNIX will work *if* you have UNIX-domain sockets configured * into the kernel and *if* you're not on a system that doesn't * allow them - some SELinux systems don't allow you create them. * Most systems probably have them configured in, but not all systems * have them configured in and allow them to be created. * * AF_INET will work *if* you have IPv4 configured into the kernel, * but, apparently, some systems have network adapters but have * kernels without IPv4 support. * * AF_INET6 will work *if* you have IPv6 configured into the * kernel, but if you don't have AF_INET, you might not have * AF_INET6, either (that is, independently on its own grounds). * * AF_PACKET would work, except that some of these calls should * work even if you *don't* have capture permission (you should be * able to enumerate interfaces and get information about them * without capture permission; you shouldn't get a failure until * you try pcap_activate()). (If you don't allow programs to * get as much information as possible about interfaces if you * don't have permission to capture, you run the risk of users * asking "why isn't it showing XXX" - or, worse, if you don't * show interfaces *at all* if you don't have permission to * capture on them, "why do no interfaces show up?" - when the * real problem is a permissions problem. Error reports of that * type require a lot more back-and-forth to debug, as evidenced * by many Wireshark bugs/mailing list questions/Q&A questions.) * * So: * * we first try an AF_NETLINK socket, where "try" includes * "try to do a device ioctl on it", as, in the future, once * pre-4.6 kernels are sufficiently rare, that will probably * be the mechanism most likely to work; * * if that fails, we try an AF_UNIX socket, as that's less * likely to be configured out on a networking-capable system * than is IP; * * if that fails, we try an AF_INET6 socket; * * if that fails, we try an AF_INET socket. */ fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC); if (fd != -1) { /* * OK, let's make sure we can do an SIOCGIFNAME * ioctl. */ struct ifreq ifr; memset(&ifr, 0, sizeof(ifr)); if (ioctl(fd, SIOCGIFNAME, &ifr) == 0 || errno != EOPNOTSUPP) { /* * It succeeded, or failed for some reason * other than "netlink sockets don't support * device ioctls". Go with the AF_NETLINK * socket. */ return (fd); } /* * OK, that didn't work, so it's as bad as "netlink * sockets aren't available". Close the socket and * drive on. */ close(fd); } /* * Now try an AF_UNIX socket. */ fd = socket(AF_UNIX, SOCK_RAW, 0); if (fd != -1) { /* * OK, we got it! */ return (fd); } /* * Now try an AF_INET6 socket. */ fd = socket(AF_INET6, SOCK_DGRAM, 0); if (fd != -1) { return (fd); } /* * Now try an AF_INET socket. * * XXX - if that fails, is there anything else we should try? * AF_CAN, for embedded systems in vehicles, in case they're * built without Internet protocol support? Any other socket * types popular in non-Internet embedded systems? */ return (socket(AF_INET, SOCK_DGRAM, 0)); } /* * Get additional flags for a device, using SIOCGIFMEDIA. */ static int get_if_flags(const char *name, bpf_u_int32 *flags, char *errbuf) { int sock; FILE *fh; unsigned int arptype; struct ifreq ifr; struct ethtool_value info; if (*flags & PCAP_IF_LOOPBACK) { /* * Loopback devices aren't wireless, and "connected"/ * "disconnected" doesn't apply to them. */ *flags |= PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE; return 0; } sock = get_if_ioctl_socket(); if (sock == -1) { pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE, errno, "Can't create socket to get ethtool information for %s", name); return -1; } /* * OK, what type of network is this? * In particular, is it wired or wireless? */ if (is_wifi(name)) { /* * Wi-Fi, hence wireless. */ *flags |= PCAP_IF_WIRELESS; } else { /* * OK, what does /sys/class/net/{if_name}/type contain? * (We don't use that for Wi-Fi, as it'll report * "Ethernet", i.e. ARPHRD_ETHER, for non-monitor- * mode devices.) */ char *pathstr; if (asprintf(&pathstr, "/sys/class/net/%s/type", name) == -1) { snprintf(errbuf, PCAP_ERRBUF_SIZE, "%s: Can't generate path name string for /sys/class/net device", name); close(sock); return -1; } fh = fopen(pathstr, "r"); if (fh != NULL) { if (fscanf(fh, "%u", &arptype) == 1) { /* * OK, we got an ARPHRD_ type; what is it? */ switch (arptype) { case ARPHRD_LOOPBACK: /* * These are types to which * "connected" and "disconnected" * don't apply, so don't bother * asking about it. * * XXX - add other types? */ close(sock); fclose(fh); free(pathstr); return 0; case ARPHRD_IRDA: case ARPHRD_IEEE80211: case ARPHRD_IEEE80211_PRISM: case ARPHRD_IEEE80211_RADIOTAP: #ifdef ARPHRD_IEEE802154 case ARPHRD_IEEE802154: #endif #ifdef ARPHRD_IEEE802154_MONITOR case ARPHRD_IEEE802154_MONITOR: #endif #ifdef ARPHRD_6LOWPAN case ARPHRD_6LOWPAN: #endif /* * Various wireless types. */ *flags |= PCAP_IF_WIRELESS; break; } } fclose(fh); } free(pathstr); } #ifdef ETHTOOL_GLINK memset(&ifr, 0, sizeof(ifr)); pcap_strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name)); info.cmd = ETHTOOL_GLINK; /* * XXX - while Valgrind handles SIOCETHTOOL and knows that * the ETHTOOL_GLINK command sets the .data member of the * structure, Memory Sanitizer doesn't yet do so: * * https://bugs.llvm.org/show_bug.cgi?id=45814 * * For now, we zero it out to squelch warnings; if the bug * in question is fixed, we can remove this. */ info.data = 0; ifr.ifr_data = (caddr_t)&info; if (ioctl(sock, SIOCETHTOOL, &ifr) == -1) { int save_errno = errno; switch (save_errno) { case EOPNOTSUPP: case EINVAL: /* * OK, this OS version or driver doesn't support * asking for this information. * XXX - distinguish between "this doesn't * support ethtool at all because it's not * that type of device" vs. "this doesn't * support ethtool even though it's that * type of device", and return "unknown". */ *flags |= PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE; close(sock); return 0; case ENODEV: /* * OK, no such device. * The user will find that out when they try to * activate the device; just say "OK" and * don't set anything. */ close(sock); return 0; default: /* * Other error. */ pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE, save_errno, "%s: SIOCETHTOOL(ETHTOOL_GLINK) ioctl failed", name); close(sock); return -1; } } /* * Is it connected? */ if (info.data) { /* * It's connected. */ *flags |= PCAP_IF_CONNECTION_STATUS_CONNECTED; } else { /* * It's disconnected. */ *flags |= PCAP_IF_CONNECTION_STATUS_DISCONNECTED; } #endif close(sock); return 0; } int pcap_platform_finddevs(pcap_if_list_t *devlistp, char *errbuf) { /* * Get the list of regular interfaces first. */ if (pcap_findalldevs_interfaces(devlistp, errbuf, can_be_bound, get_if_flags) == -1) return (-1); /* failure */ /* * Add the "any" device. * As it refers to all network devices, not to any particular * network device, the notion of "connected" vs. "disconnected" * doesn't apply. */ if (add_dev(devlistp, "any", PCAP_IF_UP|PCAP_IF_RUNNING|PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, any_descr, errbuf) == NULL) return (-1); return (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) { /* * It's guaranteed, at this point, that d is a valid * direction value. */ handle->direction = d; return 0; } static int is_wifi(const char *device) { char *pathstr; struct stat statb; /* * See if there's a sysfs wireless directory for it. * If so, it's a wireless interface. */ if (asprintf(&pathstr, "/sys/class/net/%s/wireless", device) == -1) { /* * Just give up here. */ return 0; } if (stat(pathstr, &statb) == 0) { free(pathstr); return 1; } free(pathstr); return 0; } /* * 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 packets 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; } /* * Is this a real Ethernet device? If so, 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 other 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 "setup_socket()", * as we fall back on cooked mode there, and we use * is_wifi() to check for 802.11 devices; are there any * others? */ if (!is_wifi(device)) { int ret; /* * This is not a Wi-Fi device but it could be * a DSA master/management network device. */ ret = iface_dsa_get_proto_info(device, handle); if (ret < 0) return; if (ret == 1) { /* * This is a DSA master/management network * device linktype is already set by * iface_dsa_get_proto_info() set an * appropriate offset here. */ handle->offset = 2; break; } /* * It's not a Wi-Fi device; offer DOCSIS. */ 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: * * https://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) * 3); /* * 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 setup_socket(). */ /* 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 setup_socket(). */ /* handlep->cooked = 1; */ break; #ifndef ARPHRD_VSOCKMON #define ARPHRD_VSOCKMON 826 #endif case ARPHRD_VSOCKMON: handle->linktype = DLT_VSOCK; break; default: handle->linktype = -1; break; } } static void set_dlt_list_cooked(pcap_t *handle) { /* * Support both DLT_LINUX_SLL and DLT_LINUX_SLL2. */ handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); /* * If that failed, just leave the list empty. */ if (handle->dlt_list != NULL) { handle->dlt_list[0] = DLT_LINUX_SLL; handle->dlt_list[1] = DLT_LINUX_SLL2; handle->dlt_count = 2; } } /* * Try to set up a PF_PACKET socket. * Returns 0 on success and a PCAP_ERROR_ value on failure. */ static int setup_socket(pcap_t *handle, int is_any_device) { struct pcap_linux *handlep = handle->priv; const char *device = handle->opt.device; int status = 0; int sock_fd, arptype; int val; int err = 0; struct packet_mreq mr; #if defined(SO_BPF_EXTENSIONS) && defined(SKF_AD_VLAN_TAG_PRESENT) int bpf_extensions; socklen_t len = sizeof(bpf_extensions); #endif /* * Open a socket with protocol family packet. If cooked is true, * we open a SOCK_DGRAM socket for the cooked interface, otherwise * we open a SOCK_RAW socket for the raw interface. * * The protocol is set to 0. This means we will receive no * packets until we "bind" the socket with a non-zero * protocol. This allows us to setup the ring buffers without * dropping any packets. */ sock_fd = is_any_device ? socket(PF_PACKET, SOCK_DGRAM, 0) : socket(PF_PACKET, SOCK_RAW, 0); if (sock_fd == -1) { if (errno == EPERM || errno == EACCES) { /* * You don't have permission to open the * socket. */ status = PCAP_ERROR_PERM_DENIED; snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Attempt to create packet socket failed - CAP_NET_RAW may be required"); } else { /* * Other error. */ status = PCAP_ERROR; } pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "socket"); return status; } /* * 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 the type is unknown, return a warning; * map_arphrd_to_dlt() has already set the * warning message. */ if (close(sock_fd) == -1) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "close"); return PCAP_ERROR; } sock_fd = socket(PF_PACKET, SOCK_DGRAM, 0); if (sock_fd < 0) { /* * Fatal error. We treat this as * a generic error; we already know * that we were able to open a * PF_PACKET/SOCK_RAW socket, so * any failure is a "this shouldn't * happen" case. */ pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "socket"); 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; set_dlt_list_cooked(handle); } 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; if (handle->linktype == -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "unknown arptype %d, defaulting to cooked mode", arptype); status = PCAP_WARNING; } } 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, 0)) != 0) { close(sock_fd); return err; } } 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; handle->dlt_list = NULL; handle->dlt_count = 0; set_dlt_list_cooked(handle); /* * 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) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "setsockopt (PACKET_ADD_MEMBERSHIP)"); close(sock_fd); return PCAP_ERROR; } } /* * Enable auxiliary data and reserve room for reconstructing * VLAN headers. * * XXX - is enabling auxiliary data necessary, now that we * only support memory-mapped capture? The kernel's memory-mapped * capture code doesn't seem to check whether auxiliary data * is enabled, it seems to provide it whether it is or not. */ val = 1; if (setsockopt(sock_fd, SOL_PACKET, PACKET_AUXDATA, &val, sizeof(val)) == -1 && errno != ENOPROTOOPT) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "setsockopt (PACKET_AUXDATA)"); close(sock_fd); return PCAP_ERROR; } handle->offset += VLAN_TAG_LEN; /* * 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()"). * XXX - we don't know whether this will be DLT_LINUX_SLL * or DLT_LINUX_SLL2, so make sure it's big enough for * a DLT_LINUX_SLL2 "cooked mode" header; a snapshot length * that small is silly anyway. */ if (handlep->cooked) { if (handle->snapshot < SLL2_HDR_LEN + 1) handle->snapshot = SLL2_HDR_LEN + 1; } handle->bufsize = handle->snapshot; /* * Set the offset at which to insert VLAN tags. */ set_vlan_offset(handle); 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; } } /* * We've succeeded. Save the socket FD in the pcap structure. */ handle->fd = sock_fd; #if defined(SO_BPF_EXTENSIONS) && defined(SKF_AD_VLAN_TAG_PRESENT) /* * 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 /* defined(SO_BPF_EXTENSIONS) && defined(SKF_AD_VLAN_TAG_PRESENT) */ return status; } /* * Attempt to setup 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 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 setup_mmapped(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) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "can't allocate oneshot buffer"); *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); handlep->oneshot_buffer = NULL; *status = PCAP_ERROR; return ret; } ret = create_ring(handle, status); if (ret == -1) { /* * Error attempting to enable memory-mapped capture; * fail. create_ring() has set *status. */ free(handlep->oneshot_buffer); handlep->oneshot_buffer = NULL; 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. * * handle->offset is used to get the current position into the rx ring. * handle->cc is used to store the ring size. */ /* * Set the timeout to use in poll() before returning. */ set_poll_timeout(handlep); return 1; } /* * 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; * this also gets the length of the header for that version. * * This socket option was introduced in 2.6.27, which was * also the first release with TPACKET_V2 support. */ if (getsockopt(handle->fd, SOL_PACKET, PACKET_HDRLEN, &val, &len) < 0) { if (errno == EINVAL) { /* * EINVAL means this specific version of TPACKET * is not supported. Tell the caller they can try * with a different one; if they've run out of * others to try, let them set the error message * appropriately. */ return 1; } /* * All other errors are fatal. */ if (errno == ENOPROTOOPT) { /* * PACKET_HDRLEN isn't supported, which means * that memory-mapped capture isn't supported. * Indicate that in the message. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Kernel doesn't support memory-mapped capture; a 2.6.27 or later 2.x kernel is required, with CONFIG_PACKET_MMAP specified for 2.x kernels"); } else { /* * Some unexpected error. */ pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "can't get %s header len on packet socket", version_str); } return -1; } handlep->tp_hdrlen = val; val = version; if (setsockopt(handle->fd, SOL_PACKET, PACKET_VERSION, &val, sizeof(val)) < 0) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "can't activate %s on packet socket", version_str); return -1; } handlep->tp_version = version; return 0; } /* * 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 fail. * * Return 0 if we succeed and -1 on any other error, and set handle->errbuf. */ static int prepare_tpacket_socket(pcap_t *handle) { int ret; #ifdef HAVE_TPACKET3 /* * Try setting the version to TPACKET_V3. * * 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 = init_tpacket(handle, TPACKET_V3, "TPACKET_V3"); if (ret == 0) { /* * Success. */ return 0; } if (ret == -1) { /* * We failed for some reason other than "the * kernel doesn't support TPACKET_V3". */ return -1; } /* * This means it returned 1, which means "the kernel * doesn't support TPACKET_V3"; try TPACKET_V2. */ } #endif /* HAVE_TPACKET3 */ /* * Try setting the version to TPACKET_V2. */ ret = init_tpacket(handle, TPACKET_V2, "TPACKET_V2"); if (ret == 0) { /* * Success. */ return 0; } if (ret == 1) { /* * OK, the kernel supports memory-mapped capture, but * not TPACKET_V2. Set the error message appropriately. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Kernel doesn't support TPACKET_V2; a 2.6.27 or later kernel is required"); } /* * We failed. */ return -1; } #define MAX(a,b) ((a)>(b)?(a):(b)) /* * 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 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_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; /* * Reserve space for VLAN tag reconstruction. */ tp_reserve = VLAN_TAG_LEN; /* * If we're capturing in cooked mode, reserve space for * a DLT_LINUX_SLL2 header; we don't know yet whether * we'll be using DLT_LINUX_SLL or DLT_LINUX_SLL2, as * that can be changed on an open device, so we reserve * space for the larger of the two. * * XXX - we assume that the kernel is still adding * 16 bytes of extra space, so we subtract 16 from * SLL2_HDR_LEN to get the additional space needed. * (Are they doing that for DLT_LINUX_SLL, the link- * layer header for which is 16 bytes?) * * XXX - should we use TPACKET_ALIGN(SLL2_HDR_LEN - 16)? */ if (handlep->cooked) tp_reserve += SLL2_HDR_LEN - 16; /* * Try to request that amount of reserve space. * This must be done before creating the ring buffer. */ len = sizeof(tp_reserve); if (setsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, &tp_reserve, len) < 0) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "setsockopt (PACKET_RESERVE)"); *status = PCAP_ERROR; return -1; } switch (handlep->tp_version) { case TPACKET_V2: /* Note that with large snapshot length (say 256K, which is * the default for recent versions of tcpdump, Wireshark, * TShark, dumpcap or 64K, the value that "-s 0" has given for * a long time with tcpdump), 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.) * * If segmentation/fragmentation or receive offload are * enabled, we can get reassembled/aggregated packets larger * than MTU, but bounded to 65535 plus the Ethernet overhead, * due to kernel and protocol constraints */ frame_size = handle->snapshot; if (handle->linktype == DLT_EN10MB) { unsigned int max_frame_len; int mtu; int offload; mtu = iface_get_mtu(handle->fd, handle->opt.device, handle->errbuf); if (mtu == -1) { *status = PCAP_ERROR; return -1; } offload = iface_get_offload(handle); if (offload == -1) { *status = PCAP_ERROR; return -1; } if (offload) max_frame_len = MAX(mtu, 65535); else max_frame_len = mtu; max_frame_len += 18; if (frame_size > max_frame_len) frame_size = max_frame_len; } /* 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) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "getsockopt (SO_TYPE)"); *status = PCAP_ERROR; return -1; } 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); /* * Round the buffer size up to a multiple of the * frame size (rather than rounding down, which * would give a buffer smaller than our caller asked * for, and possibly give zero frames if the requested * buffer size is too small for one frame). */ req.tp_frame_nr = (handle->opt.buffer_size + req.tp_frame_size - 1)/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 MAXIMUM_SNAPLEN to leave * enough room for at least one reasonably-sized packet * in the "frame". */ req.tp_frame_size = MAXIMUM_SNAPLEN; /* * Round the buffer size up to a multiple of the * "frame" size (rather than rounding down, which * would give a buffer smaller than our caller asked * for, and possibly give zero "frames" if the requested * buffer size is too small for one "frame"). */ req.tp_frame_nr = (handle->opt.buffer_size + req.tp_frame_size - 1)/req.tp_frame_size; break; #endif default: snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Internal error: unknown TPACKET_ value %u", handlep->tp_version); *status = PCAP_ERROR; return -1; } /* compute the minimum 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)); pcap_strlcpy(ifr.ifr_name, handle->opt.device, sizeof(ifr.ifr_name)); ifr.ifr_data = (void *)&hwconfig; /* * This may require CAP_NET_ADMIN. */ 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; snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Attempt to set hardware timestamp failed - CAP_NET_ADMIN may be required"); return -1; case EOPNOTSUPP: case ERANGE: /* * Treat this as a warning, as the * only way to fix the warning is to * get an adapter that supports hardware * time stamps for *all* packets. * (ERANGE means "we support hardware * time stamps, but for packets matching * that particular filter", so it means * "we don't support hardware time stamps * for all incoming packets" here.) * * We'll just fall back on the standard * host time stamps. */ *status = PCAP_WARNING_TSTAMP_TYPE_NOTSUP; break; default: pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "SIOCSHWTSTAMP failed"); *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))) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "can't set PACKET_TIMESTAMP"); *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. */ if (handlep->timeout > 0) { /* Use the user specified timeout as the block timeout */ req.tp_retire_blk_tov = handlep->timeout; } else if (handlep->timeout == 0) { /* * In pcap, this means "infinite timeout"; TPACKET_V3 * doesn't support that, so just set it to UINT_MAX * milliseconds. In the TPACKET_V3 loop, if the * timeout is 0, and we haven't yet seen any packets, * and we block and still don't have any packets, we * keep blocking until we do. */ req.tp_retire_blk_tov = UINT_MAX; } else { /* * XXX - this is not valid; use 0, meaning "have the * kernel pick a default", for now. */ req.tp_retire_blk_tov = 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; } pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "can't create rx ring on packet socket"); *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) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "can't mmap rx ring"); /* 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) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "can't allocate ring of frame headers"); 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) { u_char *base = &handlep->mmapbuf[i*req.tp_block_size]; for (j=0; j<frames_per_block; ++j, ++handle->offset) { RING_GET_CURRENT_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. * We don't check for setsockopt failure, as 1) we can't recover * from an error and 2) we might not yet have set it up in the * first place. */ struct tpacket_req req; memset(&req, 0, sizeof(req)); (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_linux(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 int pcap_getnonblock_linux(pcap_t *handle) { struct pcap_linux *handlep = handle->priv; /* use negative value of timeout to indicate non blocking ops */ return (handlep->timeout<0); } static int pcap_setnonblock_linux(pcap_t *handle, int nonblock) { struct pcap_linux *handlep = handle->priv; /* * Set the file descriptor to non-blocking mode, as we use * it for sending packets. */ if (pcap_setnonblock_fd(handle, nonblock) == -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; } if (handlep->poll_breakloop_fd != -1) { /* Close the eventfd; we do not need it in nonblock mode. */ close(handlep->poll_breakloop_fd); handlep->poll_breakloop_fd = -1; } } else { if (handlep->poll_breakloop_fd == -1) { /* If we did not have an eventfd, open one now that we are blocking. */ if ( ( handlep->poll_breakloop_fd = eventfd(0, EFD_NONBLOCK) ) == -1 ) { int save_errno = errno; snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Could not open eventfd: %s", strerror(errno)); errno = save_errno; return -1; } } if (handlep->timeout < 0) { handlep->timeout = ~handlep->timeout; } } /* Update the timeout to use in poll(). */ set_poll_timeout(handlep); return 0; } /* * Get the status field of the ring buffer frame at a specified offset. */ static inline u_int pcap_get_ring_frame_status(pcap_t *handle, int offset) { struct pcap_linux *handlep = handle->priv; union thdr h; h.raw = RING_GET_FRAME_AT(handle, offset); switch (handlep->tp_version) { case TPACKET_V2: return __atomic_load_n(&h.h2->tp_status, __ATOMIC_ACQUIRE); break; #ifdef HAVE_TPACKET3 case TPACKET_V3: return __atomic_load_n(&h.h3->hdr.bh1.block_status, __ATOMIC_ACQUIRE); break; #endif } /* This should not happen. */ return 0; } /* * Block waiting for frames to be available. */ static int pcap_wait_for_frames_mmap(pcap_t *handle) { struct pcap_linux *handlep = handle->priv; int timeout; struct ifreq ifr; int ret; struct pollfd pollinfo[2]; int numpollinfo; pollinfo[0].fd = handle->fd; pollinfo[0].events = POLLIN; if ( handlep->poll_breakloop_fd == -1 ) { numpollinfo = 1; pollinfo[1].revents = 0; /* * We set pollinfo[1].revents to zero, even though * numpollinfo = 1 meaning that poll() doesn't see * pollinfo[1], so that we do not have to add a * conditional of numpollinfo > 1 below when we * test pollinfo[1].revents. */ } else { pollinfo[1].fd = handlep->poll_breakloop_fd; pollinfo[1].events = POLLIN; numpollinfo = 2; } /* * Keep polling until we either get some packets to read, see * that we got told to break out of the loop, get a fatal error, * or discover that the device went away. * * In non-blocking mode, we must still do one poll() to catch * any pending error indications, but the poll() has a timeout * of 0, so that it doesn't block, and we quit after that one * poll(). * * If we've seen an ENETDOWN, it might be the first indication * that the device went away, or it might just be that it was * configured down. Unfortunately, there's no guarantee that * the device has actually been removed as an interface, because: * * 1) if, as appears to be the case at least some of the time, * the PF_PACKET socket code first gets a NETDEV_DOWN indication * for the device and then gets a NETDEV_UNREGISTER indication * for it, the first indication will cause a wakeup with ENETDOWN * but won't set the packet socket's field for the interface index * to -1, and the second indication won't cause a wakeup (because * the first indication also caused the protocol hook to be * unregistered) but will set the packet socket's field for the * interface index to -1; * * 2) even if just a NETDEV_UNREGISTER indication is registered, * the packet socket's field for the interface index only gets * set to -1 after the wakeup, so there's a small but non-zero * risk that a thread blocked waiting for the wakeup will get * to the "fetch the socket name" code before the interface index * gets set to -1, so it'll get the old interface index. * * Therefore, if we got an ENETDOWN and haven't seen a packet * since then, we assume that we might be waiting for the interface * to disappear, and poll with a timeout to try again in a short * period of time. If we *do* see a packet, the interface has * come back up again, and is *definitely* still there, so we * don't need to poll. */ for (;;) { /* * Yes, we do this even in non-blocking mode, as it's * the only way to get error indications from a * tpacket socket. * * The timeout is 0 in non-blocking mode, so poll() * returns immediately. */ timeout = handlep->poll_timeout; /* * If we got an ENETDOWN and haven't gotten an indication * that the device has gone away or that the device is up, * we don't yet know for certain whether the device has * gone away or not, do a poll() with a 1-millisecond timeout, * as we have to poll indefinitely for "device went away" * indications until we either get one or see that the * device is up. */ if (handlep->netdown) { if (timeout != 0) timeout = 1; } ret = poll(pollinfo, numpollinfo, timeout); if (ret < 0) { /* * Error. If it's not EINTR, report it. */ if (errno != EINTR) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "can't poll on packet socket"); return PCAP_ERROR; } /* * It's EINTR; if we were told to break out of * the loop, do so. */ if (handle->break_loop) { handle->break_loop = 0; return PCAP_ERROR_BREAK; } } else if (ret > 0) { /* * OK, some descriptor is ready. * Check the socket descriptor first. * * As I read the Linux man page, pollinfo[0].revents * will either be POLLIN, POLLERR, POLLHUP, or POLLNVAL. */ if (pollinfo[0].revents == POLLIN) { /* * OK, we may have packets to * read. */ break; } if (pollinfo[0].revents != 0) { /* * There's some indication other than * "you can read on this descriptor" on * the descriptor. */ if (pollinfo[0].revents & POLLNVAL) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Invalid polling request on packet socket"); return PCAP_ERROR; } if (pollinfo[0].revents & (POLLHUP | POLLRDHUP)) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Hangup on packet socket"); return PCAP_ERROR; } if (pollinfo[0].revents & POLLERR) { /* * Get the error. */ int err; socklen_t errlen; errlen = sizeof(err); if (getsockopt(handle->fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) { /* * The call *itself* returned * an error; make *that* * the error. */ err = errno; } /* * OK, we have the error. */ if (err == ENETDOWN) { /* * The device on which we're * capturing went away or the * interface was taken down. * * We don't know for certain * which happened, and the * next poll() may indicate * that there are packets * to be read, so just set * a flag to get us to do * checks later, and set * the required select * timeout to 1 millisecond * so that event loops that * check our socket descriptor * also time out so that * they can call us and we * can do the checks. */ handlep->netdown = 1; handle->required_select_timeout = &netdown_timeout; } else if (err == 0) { /* * This shouldn't happen, so * report a special indication * that it did. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Error condition on packet socket: Reported error was 0"); return PCAP_ERROR; } else { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, err, "Error condition on packet socket"); return PCAP_ERROR; } } } /* * Now check the event device. */ if (pollinfo[1].revents & POLLIN) { ssize_t nread; uint64_t value; /* * This should never fail, but, just * in case.... */ nread = read(handlep->poll_breakloop_fd, &value, sizeof(value)); if (nread == -1) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "Error reading from event FD"); return PCAP_ERROR; } /* * According to the Linux read(2) man * page, read() will transfer at most * 2^31-1 bytes, so the return value is * either -1 or a value between 0 * and 2^31-1, so it's non-negative. * * Cast it to size_t to squelch * warnings from the compiler; add this * comment to squelch warnings from * humans reading the code. :-) * * Don't treat an EOF as an error, but * *do* treat a short read as an error; * that "shouldn't happen", but.... */ if (nread != 0 && (size_t)nread < sizeof(value)) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Short read from event FD: expected %zu, got %zd", sizeof(value), nread); return PCAP_ERROR; } /* * This event gets signaled by a * pcap_breakloop() call; if we were told * to break out of the loop, do so. */ if (handle->break_loop) { handle->break_loop = 0; return PCAP_ERROR_BREAK; } } } /* * Either: * * 1) we got neither an error from poll() nor any * readable descriptors, in which case there * are no packets waiting to read * * or * * 2) We got readable descriptors but the PF_PACKET * socket wasn't one of them, in which case there * are no packets waiting to read * * so, if we got an ENETDOWN, we've drained whatever * packets were available to read at the point of the * ENETDOWN. * * So, if we got an ENETDOWN and haven't gotten an indication * that the device has gone away or that the device is up, * we don't yet know for certain whether the device has * gone away or not, check whether the device exists and is * up. */ if (handlep->netdown) { if (!device_still_exists(handle)) { /* * The device doesn't exist any more; * report that. * * XXX - we should really return an * appropriate error for that, but * pcap_dispatch() etc. aren't documented * as having error returns other than * PCAP_ERROR or PCAP_ERROR_BREAK. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "The interface disappeared"); return PCAP_ERROR; } /* * The device still exists; try to see if it's up. */ memset(&ifr, 0, sizeof(ifr)); pcap_strlcpy(ifr.ifr_name, handlep->device, sizeof(ifr.ifr_name)); if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) { if (errno == ENXIO || errno == ENODEV) { /* * OK, *now* it's gone. * * XXX - see above comment. */ snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "The interface disappeared"); return PCAP_ERROR; } else { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "%s: Can't get flags", handlep->device); return PCAP_ERROR; } } if (ifr.ifr_flags & IFF_UP) { /* * It's up, so it definitely still exists. * Cancel the ENETDOWN indication - we * presumably got it due to the interface * going down rather than the device going * away - and revert to "no required select * timeout. */ handlep->netdown = 0; handle->required_select_timeout = NULL; } } /* * If we're in non-blocking mode, just quit now, rather * than spinning in a loop doing poll()s that immediately * time out if there's no indication on any descriptor. */ if (handlep->poll_timeout == 0) break; } 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, __u16 tp_vlan_tpid) { struct pcap_linux *handlep = handle->priv; unsigned char *bp; struct sockaddr_ll *sll; struct pcap_pkthdr pcaphdr; pcap_can_socketcan_hdr *canhdr; unsigned int snaplen = tp_snaplen; struct utsname utsname; /* perform sanity check on internal offset. */ if (tp_mac + tp_snaplen > handle->bufsize) { /* * Report some system information as a debugging aid. */ if (uname(&utsname) != -1) { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "corrupted frame on kernel ring mac " "offset %u + caplen %u > frame len %d " "(kernel %.32s version %s, machine %.16s)", tp_mac, tp_snaplen, handle->bufsize, utsname.release, utsname.version, utsname.machine); } else { snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "corrupted frame on kernel ring mac " "offset %u + caplen %u > 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 required build in place the sll header*/ sll = (void *)(frame + TPACKET_ALIGN(handlep->tp_hdrlen)); if (handlep->cooked) { if (handle->linktype == DLT_LINUX_SLL2) { struct sll2_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 -= SLL2_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 sll2_header *)bp; hdrp->sll2_protocol = sll->sll_protocol; hdrp->sll2_reserved_mbz = 0; hdrp->sll2_if_index = htonl(sll->sll_ifindex); hdrp->sll2_hatype = htons(sll->sll_hatype); hdrp->sll2_pkttype = sll->sll_pkttype; hdrp->sll2_halen = sll->sll_halen; memcpy(hdrp->sll2_addr, sll->sll_addr, SLL_ADDRLEN); snaplen += sizeof(struct sll2_header); } else { 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 = htons(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; snaplen += sizeof(struct sll_header); } } else { /* * If this is a packet from a CAN device, so that * sll->sll_hatype is ARPHRD_CAN, then, as we're * not capturing in cooked mode, its link-layer * type is DLT_CAN_SOCKETCAN. Fix up the header * provided by the code below us to match what * DLT_CAN_SOCKETCAN is expected to provide. */ if (sll->sll_hatype == ARPHRD_CAN) { /* * DLT_CAN_SOCKETCAN is specified as having the * CAN ID and flags in network byte order, but * capturing on a CAN device provides it in host * byte order. Convert it to network byte order. */ canhdr = (pcap_can_socketcan_hdr *)bp; canhdr->can_id = htonl(canhdr->can_id); /* * In addition, set the CANFD_FDF flag if * the protocol is LINUX_SLL_P_CANFD, as * the protocol field itself isn't in * the packet to indicate that it's a * CAN FD packet. */ uint16_t protocol = ntohs(sll->sll_protocol); if (protocol == LINUX_SLL_P_CANFD) { canhdr->fd_flags |= CANFD_FDF; /* * Zero out all the unknown bits in * fd_flags and clear the reserved * fields, so that a program reading * this can assume that CANFD_FDF * is set because we set it, not * because some uninitialized crap * was provided in the fd_flags * field. * * (At least some LINKTYPE_CAN_SOCKETCAN * files attached to Wireshark bugs * had uninitialized junk there, so it * does happen.) * * Update this if Linux adds more flag * bits to the fd_flags field or uses * either of the reserved fields for * FD frames. */ canhdr->fd_flags &= ~(CANFD_FDF|CANFD_ESI|CANFD_BRS); canhdr->reserved1 = 0; canhdr->reserved2 = 0; } else { /* * Clear CANFD_FDF if it's set (probably * again meaning that this field is * uninitialized junk). */ canhdr->fd_flags &= ~CANFD_FDF; } } } if (handlep->filter_in_userland && handle->fcode.bf_insns) { struct pcap_bpf_aux_data aux_data; aux_data.vlan_tag_present = tp_vlan_tci_valid; aux_data.vlan_tag = tp_vlan_tci & 0x0fff; if (pcap_filter_with_aux_data(handle->fcode.bf_insns, bp, tp_len, snaplen, &aux_data) == 0) return 0; } 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) { /* update packet len */ if (handle->linktype == DLT_LINUX_SLL2) { pcaphdr.caplen += SLL2_HDR_LEN; pcaphdr.len += SLL2_HDR_LEN; } else { pcaphdr.caplen += SLL_HDR_LEN; pcaphdr.len += SLL_HDR_LEN; } } if (tp_vlan_tci_valid && handlep->vlan_offset != -1 && tp_snaplen >= (unsigned int) handlep->vlan_offset) { struct vlan_tag *tag; /* * Move everything in the header, except the type field, * down VLAN_TAG_LEN bytes, to allow us to insert the * VLAN tag between that stuff and the type field. */ bp -= VLAN_TAG_LEN; memmove(bp, bp + VLAN_TAG_LEN, handlep->vlan_offset); /* * Now insert the tag. */ tag = (struct vlan_tag *)(bp + handlep->vlan_offset); tag->vlan_tpid = htons(tp_vlan_tpid); tag->vlan_tci = htons(tp_vlan_tci); /* * Add the tag to the packet lengths. */ pcaphdr.caplen += VLAN_TAG_LEN; pcaphdr.len += VLAN_TAG_LEN; } /* * 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. * * XXX - an alternative is to put a filter, consisting * of a "ret <snaplen>" instruction, on the socket * in the activate routine, so that the truncation is * done in the kernel even if nobody specified a filter; * that means that less buffer space is consumed in * the memory-mapped buffer. */ if (pcaphdr.caplen > (bpf_u_int32)handle->snapshot) pcaphdr.caplen = handle->snapshot; /* pass the packet to the user */ callback(user, &pcaphdr, bp); return 1; } 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; union thdr h; int pkts = 0; int ret; /* wait for frames availability.*/ h.raw = RING_GET_CURRENT_FRAME(handle); if (!packet_mmap_acquire(h.h2)) { /* * The current frame is owned by the kernel; wait for * a frame to be handed to us. */ ret = pcap_wait_for_frames_mmap(handle); if (ret) { return ret; } } /* * This can conceivably process more than INT_MAX packets, * which would overflow the packet count, causing it either * to look like a negative number, and thus cause us to * return a value that looks like an error, or overflow * back into positive territory, and thus cause us to * return a too-low count. * * Therefore, if the packet count is unlimited, we clip * it at INT_MAX; this routine is not expected to * process packets indefinitely, so that's not an issue. */ if (PACKET_COUNT_IS_UNLIMITED(max_packets)) max_packets = INT_MAX; while (pkts < max_packets) { /* * Get the current ring buffer frame, and break if * it's still owned by the kernel. */ h.raw = RING_GET_CURRENT_FRAME(handle); if (!packet_mmap_acquire(h.h2)) 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, VLAN_VALID(h.h2, h.h2), h.h2->tp_vlan_tci, VLAN_TPID(h.h2, h.h2)); if (ret == 1) { pkts++; } 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. */ packet_mmap_release(h.h2); 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_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.*/ h.raw = RING_GET_CURRENT_FRAME(handle); if (!packet_mmap_v3_acquire(h.h3)) { /* * The current frame is owned by the kernel; wait * for a frame to be handed to us. */ ret = pcap_wait_for_frames_mmap(handle); if (ret) { return ret; } } } h.raw = RING_GET_CURRENT_FRAME(handle); if (!packet_mmap_v3_acquire(h.h3)) { if (pkts == 0 && handlep->timeout == 0) { /* Block until we see a packet. */ goto again; } return pkts; } /* * This can conceivably process more than INT_MAX packets, * which would overflow the packet count, causing it either * to look like a negative number, and thus cause us to * return a value that looks like an error, or overflow * back into positive territory, and thus cause us to * return a too-low count. * * Therefore, if the packet count is unlimited, we clip * it at INT_MAX; this routine is not expected to * process packets indefinitely, so that's not an issue. */ if (PACKET_COUNT_IS_UNLIMITED(max_packets)) max_packets = INT_MAX; while (pkts < max_packets) { int packets_to_read; if (handlep->current_packet == NULL) { h.raw = RING_GET_CURRENT_FRAME(handle); if (!packet_mmap_v3_acquire(h.h3)) break; handlep->current_packet = h.raw + h.h3->hdr.bh1.offset_to_first_pkt; handlep->packets_left = h.h3->hdr.bh1.num_pkts; } packets_to_read = handlep->packets_left; if (packets_to_read > (max_packets - pkts)) { /* * There are more packets in the buffer than * the number of packets we have left to * process to get up to the maximum number * of packets to process. Only process enough * of them to get us up to that maximum. */ packets_to_read = max_packets - pkts; } while (packets_to_read-- && !handle->break_loop) { 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, VLAN_VALID(tp3_hdr, &tp3_hdr->hv1), tp3_hdr->hv1.tp_vlan_tci, VLAN_TPID(tp3_hdr, &tp3_hdr->hv1)); if (ret == 1) { pkts++; } 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. */ packet_mmap_v3_release(h.h3); 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 */ /* * Attach the given BPF code to the packet capture device. */ static int pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter) { struct pcap_linux *handlep; struct sock_fprog fcode; int can_filter_in_kernel; int err = 0; int n, offset; if (!handle) return -1; if (!filter) { pcap_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 overridden if * installing a kernel filter succeeds. */ handlep->filter_in_userland = 1; /* Install kernel level filter if possible */ #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)) { 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 succeeded - 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 == ENOMEM) { /* * Either a kernel memory allocation * failure occurred, or there's too * much "other/option memory" allocated * for this socket. Suggest that they * increase the "other/option memory" * limit. */ fprintf(stderr, "Warning: Couldn't allocate kernel memory for filter: try increasing net.core.optmem_max with sysctl\n"); } else 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) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "can't remove kernel filter"); 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; /* * 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 0; /* * 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 (--offset < 0) offset = handle->cc - 1; for (n=0; n < handle->cc; ++n) { if (--offset < 0) offset = handle->cc - 1; if (pcap_get_ring_frame_status(handle, offset) != 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--; /* * 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 0; } /* * 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)); pcap_strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) { pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, errno, "SIOCGIFINDEX"); return -1; } return ifr.ifr_ifindex; } /* * Bind the socket associated with FD to the given device. * Return 0 on success or a PCAP_ERROR_ value on a hard error. */ static int iface_bind(int fd, int ifindex, char *ebuf, int protocol) { struct sockaddr_ll sll; int ret, err; socklen_t errlen = sizeof(err); memset(&sll, 0, sizeof(sll)); sll.sll_family = AF_PACKET; sll.sll_ifindex = ifindex < 0 ? 0 : ifindex; sll.sll_protocol = protocol; 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; } if (errno == ENODEV) { /* * There's nothing more to say, so clear the * error message. */ ebuf[0] = '\0'; ret = PCAP_ERROR_NO_SUCH_DEVICE; } else { ret = PCAP_ERROR; pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, errno, "bind"); } return ret; } /* Any pending errors, e.g., network is down? */ if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) { pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, errno, "getsockopt (SO_ERROR)"); return PCAP_ERROR; } 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) { pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, err, "bind"); return PCAP_ERROR; } return 0; } /* * Try to enter monitor mode. * If we have libnl, try to create a new monitor-mode device and * capture on that; otherwise, just say "not supported". */ #ifdef HAVE_LIBNL static int enter_rfmon_mode(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. */ /* * 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) { /* * Success. We don't clean up the libnl state * yet, as we'll be using it later. */ 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. */ del_mon_if(handle, sock_fd, &nlstate, device, handlep->mondevice); nl80211_cleanup(&nlstate); return PCAP_ERROR; } /* * Now configure the monitor interface up. */ memset(&ifr, 0, sizeof(ifr)); pcap_strlcpy(ifr.ifr_name, handlep->mondevice, sizeof(ifr.ifr_name)); if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "%s: Can't get flags for %s", device, handlep->mondevice); 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) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "%s: Can't set flags for %s", device, handlep->mondevice); 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; } #else /* HAVE_LIBNL */ static int enter_rfmon_mode(pcap_t *handle _U_, int sock_fd _U_, const char *device _U_) { /* * We don't have libnl, so we can't do monitor mode. */ return 0; } #endif /* HAVE_LIBNL */ #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]) /* * Set the list of time stamping types to include all types. */ static int iface_set_all_ts_types(pcap_t *handle, char *ebuf) { u_int i; handle->tstamp_type_list = malloc(NUM_SOF_TIMESTAMPING_TYPES * sizeof(u_int)); if (handle->tstamp_type_list == NULL) { pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, errno, "malloc"); return -1; } for (i = 0; i < NUM_SOF_TIMESTAMPING_TYPES; i++) handle->tstamp_type_list[i] = sof_ts_type_map[i].pcap_tstamp_val; handle->tstamp_type_count = NUM_SOF_TIMESTAMPING_TYPES; return 0; } /* * Get a list of time stamp types. */ #ifdef ETHTOOL_GET_TS_INFO static int iface_get_ts_types(const char *device, pcap_t *handle, char *ebuf) { int fd; struct ifreq ifr; struct ethtool_ts_info info; int num_ts_types; u_int i, j; /* * This doesn't apply to the "any" device; you can't say "turn on * hardware time stamping for all devices that exist now and arrange * that it be turned on for any device that appears in the future", * and not all devices even necessarily *support* hardware time * stamping, so don't report any time stamp types. */ if (strcmp(device, "any") == 0) { handle->tstamp_type_list = NULL; return 0; } /* * Create a socket from which to fetch time stamping capabilities. */ fd = get_if_ioctl_socket(); if (fd < 0) { pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, errno, "socket for SIOCETHTOOL(ETHTOOL_GET_TS_INFO)"); return -1; } memset(&ifr, 0, sizeof(ifr)); pcap_strlcpy(ifr.ifr_name, device, 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) { int save_errno = errno; close(fd); switch (save_errno) { case EOPNOTSUPP: case EINVAL: /* * OK, this OS version or driver doesn't support * asking for the time stamping types, so let's * just return all the possible types. */ if (iface_set_all_ts_types(handle, ebuf) == -1) return -1; return 0; case ENODEV: /* * OK, no such device. * The user will find that out when they try to * activate the device; just return an empty * list of time stamp types. */ handle->tstamp_type_list = NULL; return 0; default: /* * Other error. */ pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, save_errno, "%s: SIOCETHTOOL(ETHTOOL_GET_TS_INFO) ioctl failed", device); return -1; } } close(fd); /* * Do we support hardware time stamping of *all* packets? */ if (!(info.rx_filters & (1 << HWTSTAMP_FILTER_ALL))) { /* * No, so don't report any time stamp types. * * XXX - some devices either don't report * HWTSTAMP_FILTER_ALL when they do support it, or * report HWTSTAMP_FILTER_ALL but map it to only * time stamping a few PTP packets. See * http://marc.info/?l=linux-netdev&m=146318183529571&w=2 * * Maybe that got fixed later. */ handle->tstamp_type_list = NULL; return 0; } 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++; } if (num_ts_types != 0) { handle->tstamp_type_list = malloc(num_ts_types * sizeof(u_int)); if (handle->tstamp_type_list == NULL) { pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, errno, "malloc"); return -1; } 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++; } } handle->tstamp_type_count = num_ts_types; } else handle->tstamp_type_list = NULL; return 0; } #else /* ETHTOOL_GET_TS_INFO */ static int iface_get_ts_types(const char *device, pcap_t *handle, char *ebuf) { /* * This doesn't apply to the "any" device; you can't say "turn on * hardware time stamping for all devices that exist now and arrange * that it be turned on for any device that appears in the future", * and not all devices even necessarily *support* hardware time * stamping, so don't report any time stamp types. */ if (strcmp(device, "any") == 0) { handle->tstamp_type_list = NULL; return 0; } /* * We don't have an ioctl to use to ask what's supported, * so say we support everything. */ if (iface_set_all_ts_types(handle, ebuf) == -1) return -1; return 0; } #endif /* ETHTOOL_GET_TS_INFO */ #else /* defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP) */ static int iface_get_ts_types(const char *device _U_, pcap_t *p _U_, char *ebuf _U_) { /* * Nothing to fetch, so it always "succeeds". */ return 0; } #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". * * We treat EOPNOTSUPP, EINVAL and, if eperm_ok is true, EPERM as * indications that the operation isn't supported. We do EPERM * weirdly because the SIOCETHTOOL code in later kernels 1) doesn't * support ETHTOOL_GUFO, 2) also doesn't include it in the list * of ethtool operations that don't require CAP_NET_ADMIN privileges, * and 3) does the "is this permitted" check before doing the "is * this even supported" check, so it fails with "this is not permitted" * rather than "this is not even supported". To work around this * annoyance, we only treat EPERM as an error for the first feature, * and assume that they all do the same permission checks, so if the * first one is allowed all the others are allowed if supported. */ #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, int eperm_ok) { struct ifreq ifr; struct ethtool_value eval; memset(&ifr, 0, sizeof(ifr)); pcap_strlcpy(ifr.ifr_name, handle->opt.device, 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 || (errno == EPERM && eperm_ok)) { /* * 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; } pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "%s: SIOCETHTOOL(%s) ioctl failed", handle->opt.device, cmdname); return -1; } return eval.data; } /* * XXX - it's annoying that we have to check for offloading at all, but, * given that we have to, it's still annoying that we have to check for * particular types of offloading, especially that shiny new types of * offloading may be added - and, worse, may not be checkable with * a particular ETHTOOL_ operation; ETHTOOL_GFEATURES would, in * theory, give those to you, but the actual flags being used are * opaque (defined in a non-uapi header), and there doesn't seem to * be any obvious way to ask the kernel what all the offloading flags * are - at best, you can ask for a set of strings(!) to get *names* * for various flags. (That whole mechanism appears to have been * designed for the sole purpose of letting ethtool report flags * by name and set flags by name, with the names having no semantics * ethtool understands.) */ static int iface_get_offload(pcap_t *handle) { int ret; #ifdef ETHTOOL_GTSO ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GTSO, "ETHTOOL_GTSO", 0); if (ret == -1) return -1; if (ret) return 1; /* TCP segmentation 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", 0); 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", 0); 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", 0); if (ret == -1) return -1; if (ret) return 1; /* generic (large) receive offloading on */ #endif #ifdef ETHTOOL_GUFO /* * Do this one last, as support for it was removed in later * kernels, and it fails with EPERM on those kernels rather * than with EOPNOTSUPP (see explanation in comment for * iface_ethtool_flag_ioctl()). */ ret = iface_ethtool_flag_ioctl(handle, ETHTOOL_GUFO, "ETHTOOL_GUFO", 1); if (ret == -1) return -1; if (ret) return 1; /* UDP fragmentation 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 */ static struct dsa_proto { const char *name; bpf_u_int32 linktype; } dsa_protos[] = { /* * None is special and indicates that the interface does not have * any tagging protocol configured, and is therefore a standard * Ethernet interface. */ { "none", DLT_EN10MB }, { "brcm", DLT_DSA_TAG_BRCM }, { "brcm-prepend", DLT_DSA_TAG_BRCM_PREPEND }, { "dsa", DLT_DSA_TAG_DSA }, { "edsa", DLT_DSA_TAG_EDSA }, }; static int iface_dsa_get_proto_info(const char *device, pcap_t *handle) { char *pathstr; unsigned int i; /* * Make this significantly smaller than PCAP_ERRBUF_SIZE; * the tag *shouldn't* have some huge long name, and making * it smaller keeps newer versions of GCC from whining that * the error message if we don't support the tag could * overflow the error message buffer. */ char buf[128]; ssize_t r; int fd; fd = asprintf(&pathstr, "/sys/class/net/%s/dsa/tagging", device); if (fd < 0) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, fd, "asprintf"); return PCAP_ERROR; } fd = open(pathstr, O_RDONLY); free(pathstr); /* * This is not fatal, kernel >= 4.20 *might* expose this attribute */ if (fd < 0) return 0; r = read(fd, buf, sizeof(buf) - 1); if (r <= 0) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "read"); close(fd); return PCAP_ERROR; } close(fd); /* * Buffer should be LF terminated. */ if (buf[r - 1] == '\n') r--; buf[r] = '\0'; for (i = 0; i < sizeof(dsa_protos) / sizeof(dsa_protos[0]); i++) { if (strlen(dsa_protos[i].name) == (size_t)r && strcmp(buf, dsa_protos[i].name) == 0) { handle->linktype = dsa_protos[i].linktype; switch (dsa_protos[i].linktype) { case DLT_EN10MB: return 0; default: return 1; } } } snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "unsupported DSA tag: %s", buf); return PCAP_ERROR; } /* * 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)); pcap_strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); if (ioctl(fd, SIOCGIFMTU, &ifr) == -1) { pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, errno, "SIOCGIFMTU"); 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; int ret; memset(&ifr, 0, sizeof(ifr)); pcap_strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); if (ioctl(fd, SIOCGIFHWADDR, &ifr) == -1) { if (errno == ENODEV) { /* * No such device. * * There's nothing more to say, so clear * the error message. */ ret = PCAP_ERROR_NO_SUCH_DEVICE; ebuf[0] = '\0'; } else { ret = PCAP_ERROR; pcap_fmt_errmsg_for_errno(ebuf, PCAP_ERRBUF_SIZE, errno, "SIOCGIFHWADDR"); } return ret; } return ifr.ifr_hwaddr.sa_family; } static int fix_program(pcap_t *handle, struct sock_fprog *fcode) { 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) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "malloc"); 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_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(handle, 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(pcap_t *handle, struct bpf_insn *p) { /* * Existing references to auxiliary data shouldn't be adjusted. * * Note that SKF_AD_OFF is negative, but p->k is unsigned, so * we use >= and cast SKF_AD_OFF to unsigned. */ if (p->k >= (bpf_u_int32)SKF_AD_OFF) return 0; if (handle->linktype == DLT_LINUX_SLL2) { /* * What's the offset? */ if (p->k >= SLL2_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 -= SLL2_HDR_LEN; } else if (p->k == 0) { /* * 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 (p->k == 4) { /* * It's the ifindex field; map it to the * special magic kernel offset for that field. */ p->k = SKF_AD_OFF + SKF_AD_IFINDEX; } else if (p->k == 10) { /* * 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 ((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; } } else { /* * 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) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "can't get FD flags when changing filter"); return -2; } if (fcntl(handle->fd, F_SETFL, save_mode | O_NONBLOCK) < 0) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "can't set nonblocking mode when changing filter"); 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); pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, save_errno, "recv failed when changing filter"); return -2; } if (fcntl(handle->fd, F_SETFL, save_mode) == -1) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "can't restore FD flags when changing filter"); 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) { pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, errno, "can't remove kernel total filter"); return -2; /* fatal error */ } errno = save_errno; } return ret; } static int reset_kernel_filter(pcap_t *handle) { int ret; /* * 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; ret = setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER, &dummy, sizeof(dummy)); /* * Ignore ENOENT - it means "we don't have a filter", so there * was no filter to remove, and there's still no filter. * * Also ignore ENONET, as a lot of kernel versions had a * typo where ENONET, rather than ENOENT, was returned. */ if (ret == -1 && errno != ENOENT && errno != ENONET) return -1; return 0; } int pcap_set_protocol_linux(pcap_t *p, int protocol) { if (pcap_check_activated(p)) return (PCAP_ERROR_ACTIVATED); p->opt.protocol = protocol; return (0); } /* * Libpcap version string. */ const char * pcap_lib_version(void) { #if defined(HAVE_TPACKET3) return (PCAP_VERSION_STRING " (with TPACKET_V3)"); #else return (PCAP_VERSION_STRING " (with TPACKET_V2)"); #endif }