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Merge pull request #28487 from yuwata/statx-fixlets

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util: fix error handling of statx()
This commit is contained in:
Luca Boccassi 2023-07-21 23:09:40 +01:00 committed by GitHub
commit 73d6f20155
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4 changed files with 57 additions and 28 deletions
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22
src/basic/fd-util.c
View File

@ -929,17 +929,18 @@ int path_is_root_at(int dir_fd, const char *path) {
* $ mount --bind /tmp/x /tmp/x/y
*
* Note, statx() does not provide the mount ID and path_get_mnt_id_at() does not work when an old
* kernel is used without /proc mounted. In that case, let's assume that we do not have such spurious
* mount points in an early boot stage, and silently skip the following check. */
* kernel is used. In that case, let's assume that we do not have such spurious mount points in an
* early boot stage, and silently skip the following check. */
if (!FLAGS_SET(st.nsx.stx_mask, STATX_MNT_ID)) {
int mntid;
r = path_get_mnt_id_at(dir_fd, "", &mntid);
if (r == -ENOSYS)
return true; /* skip the mount ID check */
if (r < 0)
r = path_get_mnt_id_at_fallback(dir_fd, "", &mntid);
if (r < 0) {
if (ERRNO_IS_NOT_SUPPORTED(r))
return true; /* skip the mount ID check */
return r;
}
assert(mntid >= 0);
st.nsx.stx_mnt_id = mntid;
@ -949,11 +950,12 @@ int path_is_root_at(int dir_fd, const char *path) {
if (!FLAGS_SET(pst.nsx.stx_mask, STATX_MNT_ID)) {
int mntid;
r = path_get_mnt_id_at(dir_fd, "..", &mntid);
if (r == -ENOSYS)
return true; /* skip the mount ID check */
if (r < 0)
r = path_get_mnt_id_at_fallback(dir_fd, "..", &mntid);
if (r < 0) {
if (ERRNO_IS_NOT_SUPPORTED(r))
return true; /* skip the mount ID check */
return r;
}
assert(mntid >= 0);
pst.nsx.stx_mnt_id = mntid;

28
src/basic/mountpoint-util.c
View File

@ -223,7 +223,9 @@ int fd_is_mount_point(int fd, const char *filename, int flags) {
AT_STATX_DONT_SYNC, /* don't go to the network for this – for similar reasons */
STATX_TYPE,
&sx) < 0) {
if (!ERRNO_IS_NOT_SUPPORTED(errno) && !ERRNO_IS_PRIVILEGE(errno))
if (!ERRNO_IS_NOT_SUPPORTED(errno) && /* statx() is not supported by the kernel. */
!ERRNO_IS_PRIVILEGE(errno) && /* maybe filtered by seccomp. */
errno != EINVAL) /* glibc's fallback method returns EINVAL when AT_STATX_DONT_SYNC is set. */
return -errno;
/* If statx() is not available or forbidden, fall back to name_to_handle_at() below */
@ -357,9 +359,21 @@ int path_is_mount_point(const char *t, const char *root, int flags) {
return fd_is_mount_point(fd, last_path_component(t), flags);
}
int path_get_mnt_id_at_fallback(int dir_fd, const char *path, int *ret) {
int r;
assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
assert(ret);
r = name_to_handle_at_loop(dir_fd, path, NULL, ret, isempty(path) ? AT_EMPTY_PATH : 0);
if (r == 0 || is_name_to_handle_at_fatal_error(r))
return r;
return fd_fdinfo_mnt_id(dir_fd, path, isempty(path) ? AT_EMPTY_PATH : 0, ret);
}
int path_get_mnt_id_at(int dir_fd, const char *path, int *ret) {
STRUCT_NEW_STATX_DEFINE(buf);
int r;
assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
assert(ret);
@ -371,7 +385,9 @@ int path_get_mnt_id_at(int dir_fd, const char *path, int *ret) {
AT_STATX_DONT_SYNC, /* don't go to the network, mnt_id is a local concept */
STATX_MNT_ID,
&buf.sx) < 0) {
if (!ERRNO_IS_NOT_SUPPORTED(errno) && !ERRNO_IS_PRIVILEGE(errno))
if (!ERRNO_IS_NOT_SUPPORTED(errno) && /* statx() is not supported by the kernel. */
!ERRNO_IS_PRIVILEGE(errno) && /* maybe filtered by seccomp. */
errno != EINVAL) /* glibc's fallback method returns EINVAL when AT_STATX_DONT_SYNC is set. */
return -errno;
/* Fall back to name_to_handle_at() and then fdinfo if statx is not supported or we lack
@ -382,11 +398,7 @@ int path_get_mnt_id_at(int dir_fd, const char *path, int *ret) {
return 0;
}
r = name_to_handle_at_loop(dir_fd, path, NULL, ret, isempty(path) ? AT_EMPTY_PATH : 0);
if (r == 0 || is_name_to_handle_at_fatal_error(r))
return r;
return fd_fdinfo_mnt_id(dir_fd, path, isempty(path) ? AT_EMPTY_PATH : 0, ret);
return path_get_mnt_id_at_fallback(dir_fd, path, ret);
}
bool fstype_is_network(const char *fstype) {

1
src/basic/mountpoint-util.h
View File

@ -37,6 +37,7 @@
int name_to_handle_at_loop(int fd, const char *path, struct file_handle **ret_handle, int *ret_mnt_id, int flags);
int path_get_mnt_id_at_fallback(int dir_fd, const char *path, int *ret);
int path_get_mnt_id_at(int dir_fd, const char *path, int *ret);
static inline int path_get_mnt_id(const char *path, int *ret) {
return path_get_mnt_id_at(AT_FDCWD, path, ret);

34
src/basic/stat-util.c
View File

@ -394,21 +394,35 @@ bool statx_mount_same(const struct new_statx *a, const struct new_statx *b) {
a->stx_dev_minor == b->stx_dev_minor;
}
static bool is_statx_fatal_error(int err, int flags) {
assert(err < 0);
/* If statx() is not supported or if we see EPERM (which might indicate seccomp filtering or so),
* let's do a fallback. Note that on EACCES we'll not fall back, since that is likely an indication of
* fs access issues, which we should propagate. */
if (ERRNO_IS_NOT_SUPPORTED(err) || err == -EPERM)
return false;
/* When unsupported flags are specified, glibc's fallback function returns -EINVAL.
* See statx_generic() in glibc. */
if (err != -EINVAL)
return true;
if ((flags & ~(AT_EMPTY_PATH | AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW | AT_STATX_SYNC_AS_STAT)) != 0)
return false; /* Unsupported flags are specified. Let's try to use our implementation. */
return true;
}
int statx_fallback(int dfd, const char *path, int flags, unsigned mask, struct statx *sx) {
static bool avoid_statx = false;
struct stat st;
int r;
if (!avoid_statx) {
if (statx(dfd, path, flags, mask, sx) < 0) {
if (!ERRNO_IS_NOT_SUPPORTED(errno) && errno != EPERM)
return -errno;
/* If statx() is not supported or if we see EPERM (which might indicate seccomp
* filtering or so), let's do a fallback. Not that on EACCES we'll not fall back,
* since that is likely an indication of fs access issues, which we should
* propagate */
} else
return 0;
r = RET_NERRNO(statx(dfd, path, flags, mask, sx));
if (r >= 0 || is_statx_fatal_error(r, flags))
return r;
avoid_statx = true;
}