From d110a3942aca78d14929bc648aeb83ee0b245a61 Mon Sep 17 00:00:00 2001 From: Liping Zhang Date: Sat, 6 May 2017 20:28:02 +0800 Subject: [PATCH] netfilter: don't setup nat info for confirmed ct We cannot setup nat info if the ct has been confirmed already, else, different cpu may race to handle the same ct. In extreme situation, we may hit the "BUG_ON(nf_nat_initialized(ct, maniptype))" in the nf_nat_setup_info. Also running the following commands will easily hit NF_CT_ASSERT in nf_conntrack_alter_reply: # nft flush ruleset # ping -c 2 -W 1 1.1.1.111 & # nft add table t # nft add chain t c {type nat hook postrouting priority 0 \;} # nft add rule t c snat to 4.5.6.7 WARNING: CPU: 1 PID: 10065 at net/netfilter/nf_conntrack_core.c:1472 nf_conntrack_alter_reply+0x9a/0x1a0 [nf_conntrack] [...] Call Trace: nf_nat_setup_info+0xad/0x840 [nf_nat] ? deactivate_slab+0x65d/0x6c0 nft_nat_eval+0xcd/0x100 [nft_nat] nft_do_chain+0xff/0x5d0 [nf_tables] ? mark_held_locks+0x6f/0xa0 ? __local_bh_enable_ip+0x70/0xa0 ? trace_hardirqs_on_caller+0x11f/0x190 ? ipt_do_table+0x310/0x610 ? trace_hardirqs_on+0xd/0x10 ? __local_bh_enable_ip+0x70/0xa0 ? ipt_do_table+0x32b/0x610 ? __lock_acquire+0x2ac/0x1580 ? ipt_do_table+0x32b/0x610 nft_nat_do_chain+0x65/0x80 [nft_chain_nat_ipv4] nf_nat_ipv4_fn+0x1ae/0x240 [nf_nat_ipv4] nf_nat_ipv4_out+0x4a/0xf0 [nf_nat_ipv4] nft_nat_ipv4_out+0x15/0x20 [nft_chain_nat_ipv4] nf_hook_slow+0x2c/0xf0 ip_output+0x154/0x270 So for the confirmed ct, just ignore it and return NF_ACCEPT. Fixes: 9a08ecfe74d7 ("netfilter: don't attach a nat extension by default") Signed-off-by: Liping Zhang Acked-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_nat_core.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c index b48d6b5..ef0be32 100644 --- a/net/netfilter/nf_nat_core.c +++ b/net/netfilter/nf_nat_core.c @@ -409,6 +409,10 @@ nf_nat_setup_info(struct nf_conn *ct, { struct nf_conntrack_tuple curr_tuple, new_tuple; + /* Can't setup nat info for confirmed ct. */ + if (nf_ct_is_confirmed(ct)) + return NF_ACCEPT; + NF_CT_ASSERT(maniptype == NF_NAT_MANIP_SRC || maniptype == NF_NAT_MANIP_DST); BUG_ON(nf_nat_initialized(ct, maniptype)); -- 2.7.4