audit: add filtering for io_uring records

This patch adds basic audit io_uring filtering, using as much of the
existing audit filtering infrastructure as possible.  In order to do
this we reuse the audit filter rule's syscall mask for the io_uring
operation and we create a new filter for io_uring operations as
AUDIT_FILTER_URING_EXIT/audit_filter_list[7].

Thanks to Richard Guy Briggs for his review, feedback, and work on
the corresponding audit userspace changes.

Acked-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
index 2acf7ca..698b62b 100644
--- a/kernel/audit_watch.c
+++ b/kernel/audit_watch.c
@@ -183,7 +183,8 @@ int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op)
 		return -EOPNOTSUPP;
 
 	if (path[0] != '/' || path[len-1] == '/' ||
-	    krule->listnr != AUDIT_FILTER_EXIT ||
+	    (krule->listnr != AUDIT_FILTER_EXIT &&
+	     krule->listnr != AUDIT_FILTER_URING_EXIT) ||
 	    op != Audit_equal ||
 	    krule->inode_f || krule->watch || krule->tree)
 		return -EINVAL;