The patch titled
vfs: utimensat(): fix error checking for {UTIME_NOW,UTIME_OMIT} case
has been added to the -mm tree. Its filename is
vfs-utimensat-fix-error-checking-for-utime_nowutime_omit-case.patch
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------------------------------------------------------
Subject: vfs: utimensat(): fix error checking for {UTIME_NOW,UTIME_OMIT} case
From: Michael Kerrisk <mtk.manpages@xxxxxxxxxxxxxx>
The POSIX.1 draft spec for utimensat() says:
Only a process with the effective user ID equal to the
user ID of the file or with appropriate privileges may use
futimens() or utimensat() with a non-null times argument
that does not have both tv_nsec fields set to UTIME_NOW
and does not have both tv_nsec fields set to UTIME_OMIT.
If this condition is violated, then the error EPERM should result.
However, the current implementation does not generate EPERM if
one tv_nsec field is UTIME_NOW while the other is UTIME_OMIT.
It should give this error for that case.
This patch:
a) Repairs that problem.
b) Removes the now unneeded nsec_special() helper function.
c) Adds some comments to explain the checks that are being
performed.
Thanks to Miklos, who provided comments on the previous iteration
of this patch. As a result, this version is a little simpler and
and its logic is better structured.
Miklos suggested an alternative idea, migrating the
is_owner_or_cap() checks into fs/attr.c:inode_change_ok() via
the use of an ATTR_OWNER_CHECK flag. Maybe we could do that
later, but for now I've gone with this version, which is
IMO simpler, and can be more easily read as being correct.
Acked-by: Miklos Szeredi <miklos@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Ulrich Drepper <drepper@xxxxxxxxxx>
Signed-off-by: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/utimes.c | 36 +++++++++++++++++++++---------------
1 file changed, 21 insertions(+), 15 deletions(-)
diff -puN fs/utimes.c~vfs-utimensat-fix-error-checking-for-utime_nowutime_omit-case fs/utimes.c
--- a/fs/utimes.c~vfs-utimensat-fix-error-checking-for-utime_nowutime_omit-case
+++ a/fs/utimes.c
@@ -40,14 +40,9 @@ asmlinkage long sys_utime(char __user *f
#endif
-static bool nsec_special(long nsec)
-{
- return nsec == UTIME_OMIT || nsec == UTIME_NOW;
-}
-
static bool nsec_valid(long nsec)
{
- if (nsec_special(nsec))
+ if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
return true;
return nsec >= 0 && nsec <= 999999999;
@@ -106,7 +101,7 @@ long do_utimes(int dfd, char __user *fil
times[1].tv_nsec == UTIME_NOW)
times = NULL;
- /* Don't worry, the checks are done in inode_change_ok() */
+ /* In most cases, the checks are done in inode_change_ok() */
newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
if (times) {
error = -EPERM;
@@ -128,15 +123,26 @@ long do_utimes(int dfd, char __user *fil
newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
newattrs.ia_valid |= ATTR_MTIME_SET;
}
- }
- /*
- * If times is NULL or both times are either UTIME_OMIT or
- * UTIME_NOW, then need to check permissions, because
- * inode_change_ok() won't do it.
- */
- if (!times || (nsec_special(times[0].tv_nsec) &&
- nsec_special(times[1].tv_nsec))) {
+ /*
+ * For the UTIME_OMIT/UTIME_NOW and UTIME_NOW/UTIME_OMIT
+ * cases, we need to make an extra check that is not done by
+ * inode_change_ok().
+ */
+ if (((times[0].tv_nsec == UTIME_NOW &&
+ times[1].tv_nsec == UTIME_OMIT)
+ ||
+ (times[0].tv_nsec == UTIME_OMIT &&
+ times[1].tv_nsec == UTIME_NOW))
+ && !is_owner_or_cap(inode))
+ goto mnt_drop_write_and_out;
+ } else {
+
+ /*
+ * If times is NULL (or both times are UTIME_NOW),
+ * then we need to check permissions, because
+ * inode_change_ok() won't do it.
+ */
error = -EACCES;
if (IS_IMMUTABLE(inode))
goto mnt_drop_write_and_out;
_
Patches currently in -mm which might be from mtk.manpages@xxxxxxxxxxxxxx are
ipc-restore-msgpool-original-value.patch
huge-page-private-reservation-review-cleanups.patch
huge-page-private-reservation-review-cleanups-fix.patch
mm-record-map_noreserve-status-on-vmas-and-fix-small-page-mprotect-reservations.patch
hugetlb-move-reservation-region-support-earlier.patch
hugetlb-allow-huge-page-mappings-to-be-created-without-reservations.patch
hugetlb-allow-huge-page-mappings-to-be-created-without-reservations-cleanups.patch
flag-parameters-socket-and-socketpair.patch
flag-parameters-socket-and-socketpair-mips-fix.patch
flag-parameters-paccept.patch
flag-parameters-paccept-fix.patch
flag-parameters-paccept-fix-flag-parameters-arch-specific-sock_nonblock.patch
flag-parameters-paccept-flag-parameters-paccept-w-out-set_restore_sigmask.patch
flag-parameters-paccept-sys_ni.patch
flag-parameters-anon_inode_getfd-extension.patch
flag-parameters-anon_inode_getfd-extension-fix.patch
flag-parameters-signalfd.patch
flag-parameters-signalfd-fix.patch
flag-parameters-eventfd.patch
flag-parameters-eventfd-fix.patch
flag-parameters-timerfd_create.patch
flag-parameters-epoll_create.patch
flag-parameters-dup2.patch
flag-parameters-pipe.patch
flag-parameters-inotify_init.patch
flag-parameters-inotify_init-fix.patch
flag-parametersi-nonblock-in-anon_inode_getfd.patch
flag-parameters-nonblock-in-socket-and-socketpair.patch
flag-parameters-nonblock-in-signalfd.patch
flag-parameters-nonblock-in-eventfd.patch
flag-parameters-nonblock-in-timerfd_create.patch
flag-parameters-nonblock-in-pipe.patch
flag-parameters-nonblock-in-inotify_init.patch
flag-parameters-check-magic-constants.patch
flag-parameters-check-magic-constants-alpha.patch
flag-parameters-add-on-remove-epoll_create-size-param.patch
vfs-utimensat-ignore-tv_sec-if-tv_nsec-==-utime_omit-or-utime_now.patch
vfs-utimensat-be-consistent-with-utime-for-immutable-and-append-only-files.patch
vfs-utimensat-fix-error-checking-for-utime_nowutime_omit-case.patch
vfs-utimensat-fix-error-checking-for-utime_nowutime_omit-case-cleanup.patch
vfs-utimensat-fix-write-access-check-for-futimens.patch
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