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netfilter: nf_nat: fix race when unloading protocol modules

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following oops was reported:
RIP: 0010:[<ffffffffa03227f2>]  [<ffffffffa03227f2>] 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:
 [..]
 [<ffffffffa02febed>] 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 <caiqian@redhat.com>
Cc: Patrick McHardy <kaber@trash.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2013-04-11 04:22:39 +00:00 • committed by Pablo Neira Ayuso
commit c2d421e171
1 changed files with 7 additions and 33 deletions
Download patch file Download diff file Expand all files Collapse all files

40
net/netfilter/nf_nat_core.c
View file

@ -467,33 +467,22 @@ EXPORT_SYMBOL_GPL(nf_nat_packet);
struct nf_nat_proto_clean { struct nf_nat_proto_clean {
u8 l3proto; u8 l3proto;
u8 l4proto; u8 l4proto;
bool hash;
}; };
/* Clear NAT section of all conntracks, in case we're loaded again. */ /* kill conntracks with affected NAT section */
static int nf_nat_proto_clean(struct nf_conn *i, void *data) static int nf_nat_proto_remove(struct nf_conn *i, void *data)
{ {
const struct nf_nat_proto_clean *clean = data; const struct nf_nat_proto_clean *clean = data;
struct nf_conn_nat *nat = nfct_nat(i); struct nf_conn_nat *nat = nfct_nat(i);
if (!nat) if (!nat)
return 0; return 0;
if (!(i->status & IPS_SRC_NAT_DONE))
return 0;
if ((clean->l3proto && nf_ct_l3num(i) != clean->l3proto) || if ((clean->l3proto && nf_ct_l3num(i) != clean->l3proto) ||
(clean->l4proto && nf_ct_protonum(i) != clean->l4proto)) (clean->l4proto && nf_ct_protonum(i) != clean->l4proto))
return 0; return 0;
if (clean->hash) { return i->status & IPS_NAT_MASK ? 1 : 0;
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;
} }
static void nf_nat_l4proto_clean(u8 l3proto, u8 l4proto) 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; struct net *net;
rtnl_lock(); rtnl_lock();
/* Step 1 - remove from bysource hash */
clean.hash = true;
for_each_net(net) for_each_net(net)
nf_ct_iterate_cleanup(net, nf_nat_proto_clean, &clean); nf_ct_iterate_cleanup(net, nf_nat_proto_remove, &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);
rtnl_unlock(); rtnl_unlock();
} }
@ -526,16 +507,9 @@ static void nf_nat_l3proto_clean(u8 l3proto)
struct net *net; struct net *net;
rtnl_lock(); 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) 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(); rtnl_unlock();
} }
@ -773,7 +747,7 @@ static void __net_exit nf_nat_net_exit(struct net *net)
{ {
struct nf_nat_proto_clean clean = {}; 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(); synchronize_rcu();
nf_ct_free_hashtable(net->ct.nat_bysource, net->ct.nat_htable_size); nf_ct_free_hashtable(net->ct.nat_bysource, net->ct.nat_htable_size);
} }