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fs-util: make sure fsync_directory_of_file() does something useful on O_PATH fds

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When handling O_PATH fds it's safe to use the parent of
/proc/self/fd/<fd> for any kind of inode. Hence do so.
This commit is contained in:
Lennart Poettering 2021-06-15 15:57:18 +02:00
parent 105a4245ff
commit 427c934fdb
1 changed files with 25 additions and 10 deletions
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35
src/basic/fs-util.c
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@ -1378,18 +1378,39 @@ int unlinkat_deallocate(int fd, const char *name, UnlinkDeallocateFlags flags) {
}
int fsync_directory_of_file(int fd) {
_cleanup_free_ char *path = NULL;
_cleanup_close_ int dfd = -1;
struct stat st;
int r;
assert(fd >= 0);
/* We only reasonably can do this for regular files and directories, hence check for that */
/* We only reasonably can do this for regular files and directories, or for O_PATH fds, hence check
* for the inode type first */
if (fstat(fd, &st) < 0)
return -errno;
if (S_ISREG(st.st_mode)) {
if (S_ISDIR(st.st_mode)) {
dfd = openat(fd, "..", O_RDONLY|O_DIRECTORY|O_CLOEXEC, 0);
if (dfd < 0)
return -errno;
} else if (!S_ISREG(st.st_mode)) { /* Regular files are OK regardless if O_PATH or not, for all other
* types check O_PATH flag */
int flags;
flags = fcntl(fd, F_GETFL);
if (flags < 0)
return -errno;
if (!FLAGS_SET(flags, O_PATH)) /* If O_PATH this refers to the inode in the fs, in which case
* we can sensibly do what is requested. Otherwise this refers
* to a socket, fifo or device node, where the concept of a
* containing directory doesn't make too much sense. */
return -ENOTTY;
}
if (dfd < 0) {
_cleanup_free_ char *path = NULL;
r = fd_get_path(fd, &path);
if (r < 0) {
@ -1412,13 +1433,7 @@ int fsync_directory_of_file(int fd) {
dfd = open_parent(path, O_CLOEXEC|O_NOFOLLOW, 0);
if (dfd < 0)
return dfd;
} else if (S_ISDIR(st.st_mode)) {
dfd = openat(fd, "..", O_RDONLY|O_DIRECTORY|O_CLOEXEC, 0);
if (dfd < 0)
return -errno;
} else
return -ENOTTY;
}
if (fsync(dfd) < 0)
return -errno;