fixing audit rule ordering mess, part 1

Problem: ordering between the rules on exit chain is currently lost;
all watch and inode rules are listed after everything else _and_
exit,never on one kind doesn't stop exit,always on another from
being matched.

Solution: assign priorities to rules, keep track of the current
highest-priority matching rule and its result (always/never).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 14 insertions, 3 deletions

diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 0febaa0f784c..995a2e86808d 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -919,6 +919,7 @@ static struct audit_entry *audit_dupe_rule(struct audit_krule *old,
         new->action = old->action;
         for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
                 new->mask[i] = old->mask[i];
+        new->prio = old->prio;
         new->buflen = old->buflen;
         new->inode_f = old->inode_f;
         new->watch = NULL;
@@ -987,9 +988,8 @@ static void audit_update_watch(struct audit_parent *parent,
 
                 /* If the update involves invalidating rules, do the inode-based
                  * filtering now, so we don't omit records. */
-                if (invalidating && current->audit_context &&
-                    audit_filter_inodes(current, current->audit_context) == AUDIT_RECORD_CONTEXT)
-                        audit_set_auditable(current->audit_context);
+                if (invalidating && current->audit_context)
+                        audit_filter_inodes(current, current->audit_context);
 
                 nwatch = audit_dupe_watch(owatch);
                 if (IS_ERR(nwatch)) {
@@ -1258,6 +1258,9 @@ static int audit_add_watch(struct audit_krule *krule, struct nameidata *ndp,
         return ret;
 }
 
+static u64 prio_low = ~0ULL/2;
+static u64 prio_high = ~0ULL/2 - 1;
+
 /* Add rule to given filterlist if not a duplicate. */
 static inline int audit_add_rule(struct audit_entry *entry,
                                  struct list_head *list)
@@ -1319,6 +1322,14 @@ static inline int audit_add_rule(struct audit_entry *entry,
                 }
         }
 
+        entry->rule.prio = ~0ULL;
+        if (entry->rule.listnr == AUDIT_FILTER_EXIT) {
+                if (entry->rule.flags & AUDIT_FILTER_PREPEND)
+                        entry->rule.prio = ++prio_high;
+                else
+                        entry->rule.prio = --prio_low;
+        }
+
         if (entry->rule.flags & AUDIT_FILTER_PREPEND) {
                 list_add_rcu(&entry->list, list);
                 entry->rule.flags &= ~AUDIT_FILTER_PREPEND;