From c2d421e171868586939c328dfb91bab840fe4c49 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 11 Apr 2013 04:22:39 +0000 Subject: [PATCH] netfilter: nf_nat: fix race when unloading protocol modules following oops was reported: RIP: 0010:[] [] nf_nat_cleanup_conntrack+0x42/0x70 [nf_nat] RSP: 0018:ffff880202c63d40 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8801ac7bec28 RCX: ffff8801d0eedbe0 RDX: dead000000200200 RSI: 0000000000000011 RDI: ffffffffa03265b8 [..] Call Trace: [..] [] destroy_conntrack+0xbd/0x110 [nf_conntrack] Happens when a conntrack timeout expires right after first part of the nat cleanup has completed (bysrc hash removal), but before part 2 has completed (re-initialization of nat area). [ destroy callback tries to delete bysrc again ] Patrick suggested to just remove the affected conntracks -- the connections won't work properly anyway without nat transformation. So, lets do that. Reported-by: CAI Qian Cc: Patrick McHardy Signed-off-by: Florian Westphal Acked-by: Patrick McHardy Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_nat_core.c | 40 +++++++------------------------------ 1 file changed, 7 insertions(+), 33 deletions(-) diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c index 8d5769c6d16e..ad24be070e53 100644 --- a/net/netfilter/nf_nat_core.c +++ b/net/netfilter/nf_nat_core.c @@ -467,33 +467,22 @@ EXPORT_SYMBOL_GPL(nf_nat_packet); struct nf_nat_proto_clean { u8 l3proto; u8 l4proto; - bool hash; }; -/* Clear NAT section of all conntracks, in case we're loaded again. */ -static int nf_nat_proto_clean(struct nf_conn *i, void *data) +/* kill conntracks with affected NAT section */ +static int nf_nat_proto_remove(struct nf_conn *i, void *data) { const struct nf_nat_proto_clean *clean = data; struct nf_conn_nat *nat = nfct_nat(i); if (!nat) return 0; - if (!(i->status & IPS_SRC_NAT_DONE)) - return 0; + if ((clean->l3proto && nf_ct_l3num(i) != clean->l3proto) || (clean->l4proto && nf_ct_protonum(i) != clean->l4proto)) return 0; - if (clean->hash) { - spin_lock_bh(&nf_nat_lock); - hlist_del_rcu(&nat->bysource); - spin_unlock_bh(&nf_nat_lock); - } else { - memset(nat, 0, sizeof(*nat)); - i->status &= ~(IPS_NAT_MASK | IPS_NAT_DONE_MASK | - IPS_SEQ_ADJUST); - } - return 0; + return i->status & IPS_NAT_MASK ? 1 : 0; } static void nf_nat_l4proto_clean(u8 l3proto, u8 l4proto) @@ -505,16 +494,8 @@ static void nf_nat_l4proto_clean(u8 l3proto, u8 l4proto) struct net *net; rtnl_lock(); - /* Step 1 - remove from bysource hash */ - clean.hash = true; for_each_net(net) - nf_ct_iterate_cleanup(net, nf_nat_proto_clean, &clean); - synchronize_rcu(); - - /* Step 2 - clean NAT section */ - clean.hash = false; - for_each_net(net) - nf_ct_iterate_cleanup(net, nf_nat_proto_clean, &clean); + nf_ct_iterate_cleanup(net, nf_nat_proto_remove, &clean); rtnl_unlock(); } @@ -526,16 +507,9 @@ static void nf_nat_l3proto_clean(u8 l3proto) struct net *net; rtnl_lock(); - /* Step 1 - remove from bysource hash */ - clean.hash = true; - for_each_net(net) - nf_ct_iterate_cleanup(net, nf_nat_proto_clean, &clean); - synchronize_rcu(); - /* Step 2 - clean NAT section */ - clean.hash = false; for_each_net(net) - nf_ct_iterate_cleanup(net, nf_nat_proto_clean, &clean); + nf_ct_iterate_cleanup(net, nf_nat_proto_remove, &clean); rtnl_unlock(); } @@ -773,7 +747,7 @@ static void __net_exit nf_nat_net_exit(struct net *net) { struct nf_nat_proto_clean clean = {}; - nf_ct_iterate_cleanup(net, &nf_nat_proto_clean, &clean); + nf_ct_iterate_cleanup(net, &nf_nat_proto_remove, &clean); synchronize_rcu(); nf_ct_free_hashtable(net->ct.nat_bysource, net->ct.nat_htable_size); } -- 2.20.1