fs/9p: only translate RWX permissions for plain 9P2000

[ Upstream commit cd25e15e57e68a6b18dc9323047fe9c68b99290b ]

Garbage in plain 9P2000's perm bits is allowed through, which causes it
to be able to set (among others) the suid bit. This was presumably not
the intent since the unix extended bits are handled explicitly and
conditionally on .u.

Signed-off-by: Joakim Sindholt <opensource@zhasha.com>
Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 0d9b7d453a877b16b2601e8d2f468a76484ea47d..75907f77f9e38de11c141419c3503fa70fe5c49f 100644 (file)
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -87,7 +87,7 @@ static int p9mode2perm(struct v9fs_session_info *v9ses,
        int res;
        int mode = stat->mode;
 
-       res = mode & S_IALLUGO;
+       res = mode & 0777; /* S_IRWXUGO */
        if (v9fs_proto_dotu(v9ses)) {
                if ((mode & P9_DMSETUID) == P9_DMSETUID)
                        res |= S_ISUID;