apparmor: Fix failed mount permission check error message

stable inclusion
from stable-v5.10.138
commit e0ca0156a78666f630f469271b4a48ef6ddc0704
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I60QFD

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e0ca0156a78666f630f469271b4a48ef6ddc0704

--------------------------------

commit ec240b59 upstream.

When the mount check fails due to a permission check failure instead
of explicitly at one of the subcomponent checks, AppArmor is reporting
a failure in the flags match. However this is not true and AppArmor
can not attribute the error at this point to any particular component,
and should only indicate the mount failed due to missing permissions.

Fixes: 2ea3ffb7 ("apparmor: add mount mediation")
Signed-off-by: NJohn Johansen <john.johansen@canonical.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>

security/apparmor/mount.c

@@ -229,7 +229,8 @@ static const char * const mnt_info_table[] = {
 	"failed srcname match",
 	"failed type match",
 	"failed flags match",
-	"failed data match"
+	"failed data match",
+	"failed perms check"
 };
 
 /*
@@ -284,8 +285,8 @@ static int do_match_mnt(struct aa_dfa *dfa, unsigned int start,
 			return 0;
 	}
 
-	/* failed at end of flags match */
-	return 4;
+	/* failed at perms check, don't confuse with flags match */
+	return 6;
 }