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include/loopdev.h
232 строки
8 KB
Karel Zak
loopdev: add LOOPDEV_FL_NOFOLLOW to prevent symlink attacks
01 апр 2026, 11:47
01 апр 2026, 11:47
5e39046
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/* * No copyright is claimed. This code is in the public domain; do with * it what you wish. */ #ifndef UTIL_LINUX_LOOPDEV_H #define UTIL_LINUX_LOOPDEV_H #include <stdbool.h> #include "sysfs.h" /* * loop_info.lo_encrypt_type */ #define LO_CRYPT_NONE 0 #define LO_CRYPT_XOR 1 #define LO_CRYPT_DES 2 #define LO_CRYPT_CRYPTOAPI 18 #define LOOP_SET_FD 0x4C00 #define LOOP_CLR_FD 0x4C01 /* * Obsolete (kernel < 2.6) * * #define LOOP_SET_STATUS 0x4C02 * #define LOOP_GET_STATUS 0x4C03 */ #define LOOP_SET_STATUS64 0x4C04 #define LOOP_GET_STATUS64 0x4C05 /* #define LOOP_CHANGE_FD 0x4C06 */ #define LOOP_SET_CAPACITY 0x4C07 #define LOOP_SET_DIRECT_IO 0x4C08 #define LOOP_SET_BLOCK_SIZE 0x4C09 /* /dev/loop-control interface */ #ifndef LOOP_CTL_ADD # define LOOP_CTL_ADD 0x4C80 # define LOOP_CTL_REMOVE 0x4C81 # define LOOP_CTL_GET_FREE 0x4C82 #endif /* * loop_info.lo_flags */ enum { LO_FLAGS_READ_ONLY = 1, LO_FLAGS_USE_AOPS = 2, LO_FLAGS_AUTOCLEAR = 4, /* kernel >= 2.6.25 */ LO_FLAGS_PARTSCAN = 8, /* kernel >= 3.2 */ LO_FLAGS_DIRECT_IO = 16, /* kernel >= 4.2 */ }; #define LO_NAME_SIZE 64 #define LO_KEY_SIZE 32 /* * Linux LOOP_{SET,GET}_STATUS64 ioctl struct */ struct loop_info64 { uint64_t lo_device; uint64_t lo_inode; uint64_t lo_rdevice; uint64_t lo_offset; uint64_t lo_sizelimit; /* bytes, 0 == max available */ uint32_t lo_number; uint32_t lo_encrypt_type; uint32_t lo_encrypt_key_size; uint32_t lo_flags; uint8_t lo_file_name[LO_NAME_SIZE]; uint8_t lo_crypt_name[LO_NAME_SIZE]; uint8_t lo_encrypt_key[LO_KEY_SIZE]; uint64_t lo_init[2]; }; #ifndef LOOP_CONFIGURE /* * Since Linux v5.8-rc1 (commit 3448914e8cc550ba792d4ccc74471d1ca4293aae) */ # define LOOP_CONFIGURE 0x4C0A struct loop_config { uint32_t fd; uint32_t block_size; struct loop_info64 info; uint64_t __reserved[8]; }; #endif #define LOOPDEV_MAJOR 7 /* loop major number */ #define LOOPDEV_DEFAULT_NNODES 8 /* default number of loop devices */ struct loopdev_iter { FILE *proc; /* /proc/partitions */ DIR *sysblock; /* /sys/block */ int ncur; /* current position */ int *minors; /* ary of minor numbers (when scan whole /dev) */ int nminors; /* number of items in *minors */ int ct_perm; /* count permission problems */ int ct_succ; /* count number of detected devices */ bool done; /* scanning done */ bool default_check; /* check first LOOPDEV_NLOOPS */ int flags; /* LOOPITER_FL_* flags */ }; enum { LOOPITER_FL_FREE = (1 << 0), LOOPITER_FL_USED = (1 << 1) }; /* * handler for work with loop devices */ struct loopdev_cxt { char device[128]; /* device path (e.g. /dev/loop<N>) */ char *filename; /* backing file for loopcxt_set_... */ int fd; /* open(/dev/looo<N>) */ dev_t devno; /* loop device devno from /sys */ mode_t mode; /* fd mode O_{RDONLY,RDWR} */ uint64_t blocksize; /* used by loopcxt_setup_device() */ int flags; /* LOOPDEV_FL_* flags */ bool has_info; /* .info contains data */ bool extra_check; /* unusual stuff for iterator */ bool info_failed; /* LOOP_GET_STATUS ioctl failed */ bool control_ok; /* /dev/loop-control success */ bool is_lost; /* device in /sys, but missing in /dev */ struct path_cxt *sysfs; /* pointer to /sys/dev/block/<maj:min>/ */ struct loop_config config; /* for GET/SET ioctl */ struct loopdev_iter iter; /* scans /sys or /dev for used/free devices */ }; #define UL_LOOPDEVCXT_EMPTY { .fd = -1 } /* * loopdev_cxt.flags */ enum { LOOPDEV_FL_OFFSET = (1 << 4), LOOPDEV_FL_NOSYSFS = (1 << 5), LOOPDEV_FL_NOIOCTL = (1 << 6), LOOPDEV_FL_DEVSUBDIR = (1 << 7), LOOPDEV_FL_CONTROL = (1 << 8), /* system with /dev/loop-control */ LOOPDEV_FL_SIZELIMIT = (1 << 9), LOOPDEV_FL_NOFOLLOW = (1 << 10) /* O_NOFOLLOW, don't follow symlinks */ }; /* * High-level */ extern int loopmod_supports_partscan(void); extern int is_loopdev(const char *device); extern int loopdev_is_autoclear(const char *device); extern char *loopdev_get_backing_file(const char *device); extern dev_t loopcxt_get_devno(struct loopdev_cxt *lc); extern int loopdev_has_backing_file(const char *device); extern int loopcxt_is_lost(struct loopdev_cxt *lc); extern int loopdev_is_used(const char *device, const char *filename, uint64_t offset, uint64_t sizelimit, int flags); extern char *loopdev_find_by_backing_file(const char *filename, uint64_t offset, uint64_t sizelimit, int flags); extern int loopcxt_find_unused(struct loopdev_cxt *lc); extern int loopdev_detach(const char *device); extern int loopdev_count_by_backing_file(const char *filename, char **loopdev); /* * Low-level */ extern int loopcxt_init(struct loopdev_cxt *lc, int flags) __attribute__ ((warn_unused_result)); extern void loopcxt_deinit(struct loopdev_cxt *lc); extern int loopcxt_set_device(struct loopdev_cxt *lc, const char *device) __attribute__ ((warn_unused_result)); extern int loopcxt_has_device(struct loopdev_cxt *lc); extern int loopcxt_add_device(struct loopdev_cxt *lc); extern char *loopcxt_strdup_device(struct loopdev_cxt *lc); extern const char *loopcxt_get_device(struct loopdev_cxt *lc); extern struct loop_info64 *loopcxt_get_info(struct loopdev_cxt *lc); extern int loopcxt_get_fd(struct loopdev_cxt *lc); extern int loopcxt_init_iterator(struct loopdev_cxt *lc, int flags); extern int loopcxt_deinit_iterator(struct loopdev_cxt *lc); extern int loopcxt_next(struct loopdev_cxt *lc); extern int loopcxt_setup_device(struct loopdev_cxt *lc); extern int loopcxt_detach_device(struct loopdev_cxt *lc); extern int loopcxt_remove_device(struct loopdev_cxt *lc); extern int loopcxt_ioctl_status(struct loopdev_cxt *lc); extern int loopcxt_ioctl_capacity(struct loopdev_cxt *lc); extern int loopcxt_ioctl_dio(struct loopdev_cxt *lc, unsigned long use_dio); extern int loopcxt_ioctl_blocksize(struct loopdev_cxt *lc, uint64_t blocksize); int loopcxt_set_offset(struct loopdev_cxt *lc, uint64_t offset); int loopcxt_set_sizelimit(struct loopdev_cxt *lc, uint64_t sizelimit); int loopcxt_set_blocksize(struct loopdev_cxt *lc, uint64_t blocksize); int loopcxt_set_flags(struct loopdev_cxt *lc, uint32_t flags); int loopcxt_set_backing_file(struct loopdev_cxt *lc, const char *filename); int loopcxt_set_refname(struct loopdev_cxt *lc, const char *refname); extern char *loopcxt_get_backing_file(struct loopdev_cxt *lc); extern char *loopcxt_get_refname(struct loopdev_cxt *lc); extern int loopcxt_get_backing_devno(struct loopdev_cxt *lc, dev_t *devno); extern int loopcxt_get_backing_inode(struct loopdev_cxt *lc, ino_t *ino); extern int loopcxt_get_offset(struct loopdev_cxt *lc, uint64_t *offset); extern int loopcxt_get_blocksize(struct loopdev_cxt *lc, uint64_t *blocksize); extern int loopcxt_get_sizelimit(struct loopdev_cxt *lc, uint64_t *size); extern int loopcxt_get_encrypt_type(struct loopdev_cxt *lc, uint32_t *type); extern const char *loopcxt_get_crypt_name(struct loopdev_cxt *lc); extern int loopcxt_is_autoclear(struct loopdev_cxt *lc); extern int loopcxt_is_readonly(struct loopdev_cxt *lc); extern int loopcxt_is_dio(struct loopdev_cxt *lc); extern int loopcxt_is_partscan(struct loopdev_cxt *lc); extern int loopcxt_find_by_backing_file(struct loopdev_cxt *lc, const char *filename, uint64_t offset, uint64_t sizelimit, int flags); extern int loopcxt_find_overlap(struct loopdev_cxt *lc, const char *filename, uint64_t offset, uint64_t sizelimit); extern int loopcxt_is_used(struct loopdev_cxt *lc, struct stat *st, const char *backing_file, uint64_t offset, uint64_t sizelimit, int flags); #endif /* UTIL_LINUX_LOOPDEV_H */