From 71c3693c618189fa097eed1113aa1dd86f032cee Mon Sep 17 00:00:00 2001 From: Franck Bui Date: Wed, 11 Apr 2018 16:58:49 +0200 Subject: [PATCH] fs-util: introduce fchmod_opath() fchmod(2) still doesn't take file descriptors opened with O_PATH. --- src/basic/fs-util.c | 67 +++++++++++++++++++++++++++++++++++++++------ src/basic/fs-util.h | 2 ++ 2 files changed, 61 insertions(+), 8 deletions(-) diff --git a/src/basic/fs-util.c b/src/basic/fs-util.c index 7ccd6da21..77f00820b 100644 --- a/src/basic/fs-util.c +++ b/src/basic/fs-util.c @@ -250,6 +250,21 @@ int fchmod_umask(int fd, mode_t m) { return r; } +int fchmod_opath(int fd, mode_t m) { + char procfs_path[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(int)]; + + /* This function operates also on fd that might have been opened with + * O_PATH. Indeed fchmodat() doesn't have the AT_EMPTY_PATH flag like + * fchownat() does. */ + + xsprintf(procfs_path, "/proc/self/fd/%i", fd); + + if (chmod(procfs_path, m) < 0) + return -errno; + + return 0; +} + int fd_warn_permissions(const char *path, int fd) { struct stat st; @@ -579,10 +594,6 @@ int inotify_add_watch_fd(int fd, int what, uint32_t mask) { } #endif // 0 -static bool noop_root(const char *root) { - return isempty(root) || path_equal(root, "/"); -} - static bool safe_transition(const struct stat *a, const struct stat *b) { /* Returns true if the transition from a to b is safe, i.e. that we never transition from unprivileged to * privileged files or directories. Why bother? So that unprivileged code can't symlink to privileged files @@ -657,7 +668,7 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags, * */ /* A root directory of "/" or "" is identical to none */ - if (noop_root(original_root)) + if (empty_or_root(original_root)) original_root = NULL; if (!original_root && !ret && (flags & (CHASE_NONEXISTENT|CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_OPEN|CHASE_STEP)) == CHASE_OPEN) { @@ -742,7 +753,7 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags, /* If we already are at the top, then going up will not change anything. This is in-line with * how the kernel handles this. */ - if (isempty(done) || path_equal(done, "/")) + if (empty_or_root(done)) continue; parent = dirname_malloc(done); @@ -963,7 +974,7 @@ int chase_symlinks_and_open( if (chase_flags & CHASE_NONEXISTENT) return -EINVAL; - if (noop_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) { + if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) { /* Shortcut this call if none of the special features of this call are requested */ r = open(path, open_flags); if (r < 0) @@ -1003,7 +1014,7 @@ int chase_symlinks_and_opendir( if (chase_flags & CHASE_NONEXISTENT) return -EINVAL; - if (noop_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) { + if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) { /* Shortcut this call if none of the special features of this call are requested */ d = opendir(path); if (!d) @@ -1029,6 +1040,46 @@ int chase_symlinks_and_opendir( return 0; } +int chase_symlinks_and_stat( + const char *path, + const char *root, + unsigned chase_flags, + char **ret_path, + struct stat *ret_stat) { + + _cleanup_close_ int path_fd = -1; + _cleanup_free_ char *p = NULL; + + assert(path); + assert(ret_stat); + + if (chase_flags & CHASE_NONEXISTENT) + return -EINVAL; + + if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) { + /* Shortcut this call if none of the special features of this call are requested */ + if (stat(path, ret_stat) < 0) + return -errno; + + return 1; + } + + path_fd = chase_symlinks(path, root, chase_flags|CHASE_OPEN, ret_path ? &p : NULL); + if (path_fd < 0) + return path_fd; + + if (fstat(path_fd, ret_stat) < 0) + return -errno; + + if (ret_path) + *ret_path = TAKE_PTR(p); + + if (chase_flags & CHASE_OPEN) + return TAKE_FD(path_fd); + + return 1; +} + int access_fd(int fd, int mode) { char p[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(fd) + 1]; int r; diff --git a/src/basic/fs-util.h b/src/basic/fs-util.h index 654922fd1..b5bc5c3bc 100644 --- a/src/basic/fs-util.h +++ b/src/basic/fs-util.h @@ -39,6 +39,7 @@ int readlink_and_make_absolute(const char *p, char **r); int chmod_and_chown(const char *path, mode_t mode, uid_t uid, gid_t gid); int fchmod_umask(int fd, mode_t mode); +int fchmod_opath(int fd, mode_t m); int fd_warn_permissions(const char *path, int fd); @@ -101,6 +102,7 @@ int chase_symlinks(const char *path_with_prefix, const char *root, unsigned flag int chase_symlinks_and_open(const char *path, const char *root, unsigned chase_flags, int open_flags, char **ret_path); int chase_symlinks_and_opendir(const char *path, const char *root, unsigned chase_flags, char **ret_path, DIR **ret_dir); +int chase_symlinks_and_stat(const char *path, const char *root, unsigned chase_flags, char **ret_path, struct stat *ret_stat); /* Useful for usage with _cleanup_(), removes a directory and frees the pointer */ static inline void rmdir_and_free(char *p) { -- 2.30.2