CVE-2025-22021
netfilter: socket: Lookup orig tuple for IPv6 SNAT
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netfilter: socket: Lookup orig tuple for IPv6 SNAT
In the Linux kernel, the following vulnerability has been resolved: netfilter: socket: Lookup orig tuple for IPv6 SNAT 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.
Reserved 2024-12-29 | Published 2025-04-16 | Updated 2025-05-04 | Assigner Linuxgit.kernel.org/...c/6488b96a79a26e19100ad872622f04e93b638d7f
git.kernel.org/...c/58ab63d3ded2ca6141357a2b24eee8453d0f871d
git.kernel.org/...c/1ca2169cc19dca893c7aae6af122852097435d16
git.kernel.org/...c/1ec43100f7123010730b7ddfc3d5c2eac19e70e7
git.kernel.org/...c/5251041573850e5020cd447374e23010be698898
git.kernel.org/...c/2bb139e483f8cbe488d19d8c1135ac3615e2668c
git.kernel.org/...c/41904cbb343d115931d6bf79aa2c815cac4ef72b
git.kernel.org/...c/221c27259324ec1404f028d4f5a0f2ae7f63ee23
git.kernel.org/...c/932b32ffd7604fb00b5c57e239a3cc4d901ccf6e
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