netfilter: ipset: ipset list may return wrong member count for set with timeout

Simple testcase:

$ ipset create test hash:ip timeout 5
$ ipset add test 1.2.3.4
$ ipset add test 1.2.2.2
$ sleep 5

$ ipset l
Name: test
Type: hash:ip
Revision: 5
Header: family inet hashsize 1024 maxelem 65536 timeout 5
Size in memory: 296
References: 0
Number of entries: 2
Members:

We return "Number of entries: 2" but no members are listed. That is
because mtype_list runs "ip_set_timeout_expired" and does not list the
expired entries, but set->elements is never upated (until mtype_gc
cleans it up later).

Reviewed-by: Joshua Hunt <johunt@akamai.com>
Signed-off-by: Vishwanath Pai <vpai@akamai.com>
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h
index f236c0bc7b3f3e171e4303dd7c5379f34011812f..51063d9ed0f75d53be7a59738bf859570cd67d9b 100644 (file)
--- a/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/net/netfilter/ipset/ip_set_hash_gen.h
@@ -1041,12 +1041,24 @@ out:
 static int
 mtype_head(struct ip_set *set, struct sk_buff *skb)
 {
-       const struct htype *h = set->data;
+       struct htype *h = set->data;
        const struct htable *t;
        struct nlattr *nested;
        size_t memsize;
        u8 htable_bits;
 
+       /* If any members have expired, set->elements will be wrong
+        * mytype_expire function will update it with the right count.
+        * we do not hold set->lock here, so grab it first.
+        * set->elements can still be incorrect in the case of a huge set,
+        * because elements might time out during the listing.
+        */
+       if (SET_WITH_TIMEOUT(set)) {
+               spin_lock_bh(&set->lock);
+               mtype_expire(set, h);
+               spin_unlock_bh(&set->lock);
+       }
+
        rcu_read_lock_bh();
        t = rcu_dereference_bh_nfnl(h->table);
        memsize = mtype_ahash_memsize(h, t) + set->ext_size;