[v2,1/4] fs/posix_acl: apply umask if superblock disables ACL support
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Message ID 20190713041200.18566-1-mk@cm4all.com
State New
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Series
  • [v2,1/4] fs/posix_acl: apply umask if superblock disables ACL support
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Commit Message

Max Kellermann July 13, 2019, 4:11 a.m. UTC
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 <mk@cm4all.com>
Cc: stable@vger.kernel.org
---
 fs/posix_acl.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Comments

J. Bruce Fields Aug. 20, 2019, 9:26 p.m. UTC | #1
What happened to these patches?  All four make sense to me, for what
it's worth; feel free to add a

	Reviewed-by: J. Bruce Fields <bfields@redhat.com>

--b.

On Sat, Jul 13, 2019 at 06:11:57AM +0200, Max Kellermann wrote:
> 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 <mk@cm4all.com>
> Cc: stable@vger.kernel.org
> ---
>  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 84ad1c90d535..4071c66f234a 100644
> --- a/fs/posix_acl.c
> +++ b/fs/posix_acl.c
> @@ -589,9 +589,14 @@ 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

Patch
diff mbox series

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 84ad1c90d535..4071c66f234a 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -589,9 +589,14 @@  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();