From: Maxim Mikityanskiy <maxtram95@gmail.com> stable inclusion from stable-v6.6.86 commit 5251041573850e5020cd447374e23010be698898 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IC1PGJ CVE: CVE-2025-22021 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 932b32ffd7604fb00b5c57e239a3cc4d901ccf6e upstream. nf_sk_lookup_slow_v4 does the conntrack lookup for IPv4 packets to restore the original 5-tuple in case of SNAT, to be able to find the right socket (if any). Then socket_match() can correctly check whether the socket was transparent. However, the IPv6 counterpart (nf_sk_lookup_slow_v6) lacks this conntrack lookup, making xt_socket fail to match on the socket when the packet was SNATed. Add the same logic to nf_sk_lookup_slow_v6. IPv6 SNAT is used in Kubernetes clusters for pod-to-world packets, as pods' addresses are in the fd00::/8 ULA subnet and need to be replaced with the node's external address. Cilium leverages Envoy to enforce L7 policies, and Envoy uses transparent sockets. Cilium inserts an iptables prerouting rule that matches on `-m socket --transparent` and redirects the packets to localhost, but it fails to match SNATed IPv6 packets due to that missing conntrack lookup. Closes: https://github.com/cilium/cilium/issues/37932 Fixes: eb31628e37a0 ("netfilter: nf_tables: Add support for IPv6 NAT") Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com> Reviewed-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- net/ipv6/netfilter/nf_socket_ipv6.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/net/ipv6/netfilter/nf_socket_ipv6.c b/net/ipv6/netfilter/nf_socket_ipv6.c index a7690ec62325..9ea5ef56cb27 100644 --- a/net/ipv6/netfilter/nf_socket_ipv6.c +++ b/net/ipv6/netfilter/nf_socket_ipv6.c @@ -103,6 +103,10 @@ struct sock *nf_sk_lookup_slow_v6(struct net *net, const struct sk_buff *skb, struct sk_buff *data_skb = NULL; int doff = 0; int thoff = 0, tproto; +#if IS_ENABLED(CONFIG_NF_CONNTRACK) + enum ip_conntrack_info ctinfo; + struct nf_conn const *ct; +#endif tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL); if (tproto < 0) { @@ -136,6 +140,25 @@ struct sock *nf_sk_lookup_slow_v6(struct net *net, const struct sk_buff *skb, return NULL; } +#if IS_ENABLED(CONFIG_NF_CONNTRACK) + /* Do the lookup with the original socket address in + * case this is a reply packet of an established + * SNAT-ted connection. + */ + ct = nf_ct_get(skb, &ctinfo); + if (ct && + ((tproto != IPPROTO_ICMPV6 && + ctinfo == IP_CT_ESTABLISHED_REPLY) || + (tproto == IPPROTO_ICMPV6 && + ctinfo == IP_CT_RELATED_REPLY)) && + (ct->status & IPS_SRC_NAT_DONE)) { + daddr = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.in6; + dport = (tproto == IPPROTO_TCP) ? + ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port : + ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port; + } +#endif + return nf_socket_get_sock_v6(net, data_skb, doff, tproto, saddr, daddr, sport, dport, indev); } -- 2.25.1