From: Florian Westphal fw@strlen.de
mainline inclusion from mainline-v5.9-rc4 commit c46172147ebbeb70094db48d76ab7945d96c638b category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I63OS1 CVE: NA
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Its possible that we have more than one packet with the same ct tuple simultaneously, e.g. when an application emits n packets on same UDP socket from multiple threads.
NAT rules might be applied to those packets. With the right set of rules, n packets will be mapped to m destinations, where at least two packets end up with the same destination.
When this happens, the existing clash resolution may merge the skb that is processed after the first has been received with the identical tuple already in hash table.
However, its possible that this identical tuple is a NAT_CLASH tuple. In that case the second skb will be sent, but no reply can be received since the reply that is processed first removes the NAT_CLASH tuple.
Do not auto-delete, this gives a 1 second window for replies to be passed back to originator.
Packets that are coming later (udp stream case) will not be affected: they match the original ct entry, not a NAT_CLASH one.
Also prevent NAT_CLASH entries from getting offloaded.
Fixes: 6a757c07e51f ("netfilter: conntrack: allow insertion of clashing entries") Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org
conflict: net/netfilter/nf_conntrack_proto_udp.c
Signed-off-by: Lu Wei luwei32@huawei.com --- net/netfilter/nf_conntrack_proto_udp.c | 20 ++++++-------------- net/netfilter/nft_flow_offload.c | 2 +- 2 files changed, 7 insertions(+), 15 deletions(-)
diff --git a/net/netfilter/nf_conntrack_proto_udp.c b/net/netfilter/nf_conntrack_proto_udp.c index f4cc96261c67..83ad9f53afe3 100644 --- a/net/netfilter/nf_conntrack_proto_udp.c +++ b/net/netfilter/nf_conntrack_proto_udp.c @@ -37,18 +37,6 @@ static unsigned int *udp_get_timeouts(struct net *net) return nf_udp_pernet(net)->timeouts; }
-static void nf_conntrack_udp_refresh_unreplied(struct nf_conn *ct, - struct sk_buff *skb, - enum ip_conntrack_info ctinfo, - u32 extra_jiffies) -{ - if (unlikely(ctinfo == IP_CT_ESTABLISHED_REPLY && - ct->status & IPS_NAT_CLASH)) - nf_ct_kill(ct); - else - nf_ct_refresh_acct(ct, ctinfo, skb, extra_jiffies); -} - /* Returns verdict for packet, and may modify conntracktype */ static int udp_packet(struct nf_conn *ct, const struct sk_buff *skb, @@ -66,12 +54,16 @@ static int udp_packet(struct nf_conn *ct, if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_REPLIED]); + + /* never set ASSURED for IPS_NAT_CLASH, they time out soon */ + if (unlikely((ct->status & IPS_NAT_CLASH))) + return NF_ACCEPT; + /* Also, more likely to be important, and not a probe */ if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status)) nf_conntrack_event_cache(IPCT_ASSURED, ct); } else { - nf_conntrack_udp_refresh_unreplied(ct, skb, ctinfo, - timeouts[UDP_CT_UNREPLIED]); + nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_UNREPLIED]); } return NF_ACCEPT; } diff --git a/net/netfilter/nft_flow_offload.c b/net/netfilter/nft_flow_offload.c index 166edea0e452..df545267b933 100644 --- a/net/netfilter/nft_flow_offload.c +++ b/net/netfilter/nft_flow_offload.c @@ -100,7 +100,7 @@ static void nft_flow_offload_eval(const struct nft_expr *expr, }
if (nf_ct_ext_exist(ct, NF_CT_EXT_HELPER) || - ct->status & IPS_SEQ_ADJUST) + ct->status & (IPS_SEQ_ADJUST | IPS_NAT_CLASH)) goto out;
if (!nf_ct_is_confirmed(ct))