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Subject[PATCH 1/4] fs/posix_acl: apply umask if superblock disables ACL support
Date
The function posix_acl_create() applies the umask only if the inode
has no ACL (= NULL) or if ACLs are not supported by the filesystem
driver (= -EOPNOTSUPP).

However, this happens only after after the IS_POSIXACL() check
succeeeded. If the superblock doesn't enable ACL support, umask will
never be applied. A filesystem which has no ACL support will of
course not enable SB_POSIXACL, rendering the umask-applying code path
unreachable.

This fixes a bug which causes the umask to be ignored with O_TMPFILE
on tmpfs:

https://github.com/MusicPlayerDaemon/MPD/issues/558
https://bugs.gentoo.org/show_bug.cgi?id=686142#c3
https://bugzilla.kernel.org/show_bug.cgi?id=203625

Signed-off-by: Max Kellermann <max.kellermann@gmail.com>
---
fs/posix_acl.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 2fd0fde16fe1..815f7b36ef94 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -588,9 +588,14 @@ posix_acl_create(struct inode *dir, umode_t *mode,
*acl = NULL;
*default_acl = NULL;

- if (S_ISLNK(*mode) || !IS_POSIXACL(dir))
+ if (S_ISLNK(*mode))
return 0;

+ if (!IS_POSIXACL(dir)) {
+ *mode &= ~current_umask();
+ return 0;
+ }
+
p = get_acl(dir, ACL_TYPE_DEFAULT);
if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
*mode &= ~current_umask();
--
2.20.1
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