apparmor: add outofband transition and use it in xattr match

There are cases where the a special out of band transition that can
not be triggered by input is useful in separating match conditions
in the dfa encoding.

The null_transition is currently used as an out of band transition
for match conditions that can not contain a \0 in their input
but apparmor needs an out of band transition for cases where
the match condition is allowed to contain any input character.

Achieve this by allowing for an explicit transition out of input
range that can only be triggered by code.

Signed-off-by: John Johansen <john.johansen@canonical.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index be6dc548d307..d7a179cdaa1e 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -591,7 +591,7 @@ static __poll_t ns_revision_poll(struct file *file, poll_table *pt)
 
 void __aa_bump_ns_revision(struct aa_ns *ns)
 {
-	WRITE_ONCE(ns->revision, ns->revision + 1);
+	WRITE_ONCE(ns->revision, READ_ONCE(ns->revision) + 1);
 	wake_up_interruptible(&ns->wait);
 }
 
@@ -2331,6 +2331,8 @@ static struct aa_sfs_entry aa_sfs_entry_versions[] = {
 static struct aa_sfs_entry aa_sfs_entry_policy[] = {
 	AA_SFS_DIR("versions",			aa_sfs_entry_versions),
 	AA_SFS_FILE_BOOLEAN("set_load",		1),
+	/* number of out of band transitions supported */
+	AA_SFS_FILE_U64("outofband",		MAX_OOB_SUPPORTED),
 	{ }
 };