kernel/linux.git/net/ipv6/ip6_vti.c, branch v7.1

ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()

2026-06-10T15:16:07+00:00

In vti6_tnl_lookup(), when an exact match for a tunnel fails, the code falls back to searching for wildcard tunnels: - Tunnels matching the packet's local address, with any remote address wildcard remote). - Tunnels matching the packet's remote address, with any local address (wildcard local). However, vti6 stores all these different types of tunnels in the same hash table (ip6n->tnls_r_l) prone to hash collisions. The bug is that the fallback search loops in vti6_tnl_lookup() were missing checks to ensure that the candidate tunnel actually has a wildcard address. Fixes: fbe68ee87522 ("vti6: Add a lookup method for tunnels with wildcard endpoints.") Signed-off-by: Eric Dumazet Cc: Steffen Klassert Reviewed-by: Nicolas Dichtel Link: https://patch.msgid.link/20260608164613.933023-1-edumazet@google.com Signed-off-by: Jakub Kicinski

ip6_vti: set netns_immutable on the fallback device.

2026-06-10T01:15:47+00:00

john1988 and Noam Rathaus reported that vti6_init_net() does not set the netns_immutable flag on the per-netns fallback tunnel device (ip6_vti0). Other similar tunnel drivers (like ip6_tunnel, sit, ip6_gre, and ip_tunnel) correctly set this flag during their fallback device initialization to prevent them from being moved to another network namespace. Fixes: 61220ab34948 ("vti6: Enable namespace changing") Reported-by: Noam Rathaus Signed-off-by: Eric Dumazet Cc: Steffen Klassert Reviewed-by: Nicolas Dichtel Link: https://patch.msgid.link/20260608155918.787644-1-edumazet@google.com Signed-off-by: Jakub Kicinski

ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate().

2026-05-26T09:16:12+00:00

After patch 1/2 in this series, vti6_update() unlinks and relinks the tunnel through t->net. vti6_siocdevprivate() still uses dev_net(dev) for the collision lookup. For a tunnel moved through IFLA_NET_NS_FD, dev_net(dev) is the new netns, not t->net. SIOCCHGTUNNEL on a migrated tunnel then runs: net = dev_net(dev) /* migrated netns */ t = vti6_locate(net, &p1, false) /* misses target in t->net */ ... t = netdev_priv(dev) vti6_update(t, &p1, false) /* mutates t->net's hash */ A caller in the migrated netns picks params that match a tunnel in the creation netns. The lookup in dev_net(dev) finds nothing. vti6_update() prepends the migrated tunnel at the head of the creation netns hash bucket for those params. Later lookups in the creation netns resolve to the migrated device. xfrm receive delivers the matched packets through a device the caller controls. Reachable from an unprivileged user namespace (unshare --user --map-root-user --net). Cross tenant scope on container hosts. Switch the SIOCCHGTUNNEL path on a non fallback device to use t->net for the lookup. The lookup now matches the netns vti6_update() operates on. Also add ns_capable(self->net->user_ns, CAP_NET_ADMIN) before the lookup. The check at the top of the case is against dev_net(dev)->user_ns, which after migration is the attacker's netns. A caller there can pick params absent from self->net, the lookup returns NULL, t becomes self, and vti6_update() inserts the device into the creation netns hash. The new check requires CAP_NET_ADMIN in the creation netns user_ns too. SIOCADDTUNNEL and SIOCCHGTUNNEL on the fallback device keep dev_net(dev), which equals init_net there. Fixes: 61220ab34948 ("vti6: Enable namespace changing") Suggested-by: Jakub Kicinski Suggested-by: Xiao Liang Cc: stable@vger.kernel.org # v5.15+ Signed-off-by: Maoyi Xie Link: https://patch.msgid.link/20260521130555.3421684-3-maoyixie.tju@gmail.com Signed-off-by: Paolo Abeni

ip6: vti: Use ip6_tnl.net in vti6_changelink().

2026-05-26T09:16:12+00:00

ip netns add ns1 ip netns add ns2 ip -n ns1 link add vti6_test type vti6 remote ::1 local ::2 key 7 ip -n ns1 link set vti6_test netns ns2 ip -n ns2 link set vti6_test type vti6 remote ::3 local ::4 key 9 ip netns del ns2 ip netns del ns1 [ 132.495484] ------------[ cut here ]------------ [ 132.497609] kernel BUG at net/core/dev.c:12376! Commit 61220ab34948 ("vti6: Enable namespace changing") dropped NETIF_F_NETNS_LOCAL from vti6 devices. A vti6 tunnel can then move through IFLA_NET_NS_FD. After the move dev_net(dev) points at the new netns while t->net stays at the creation netns. vti6_changelink() and vti6_update() still use dev_net(dev) and dev_net(t->dev). They unlink from one per netns hash and relink into another. The creation netns is left with a stale entry. cleanup_net() of that netns later walks freed memory. Reachable from an unprivileged user namespace (unshare --user --map-root-user --net). Cross tenant scope on container hosts. Fixes: 61220ab34948 ("vti6: Enable namespace changing") Reported-by: Maoyi Xie Reviewed-by: Eric Dumazet Cc: stable@vger.kernel.org # v5.15+ Signed-off-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260521130555.3421684-2-maoyixie.tju@gmail.com Signed-off-by: Paolo Abeni

ipv6: adopt skb_dst_dev() and skb_dst_dev_net[_rcu]() helpers

2025-07-02T21:32:30+00:00

Use the new helpers as a step to deal with potential dst->dev races. v2: fix typo in ipv6_rthdr_rcv() (kernel test robot ) Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250630121934.3399505-10-edumazet@google.com Signed-off-by: Jakub Kicinski

ipv6: adopt dst_dev() helper

2025-07-02T21:32:30+00:00

Use the new helper as a step to deal with potential dst->dev races. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250630121934.3399505-9-edumazet@google.com Signed-off-by: Jakub Kicinski

ipv6: Convert tunnel devices' ->exit_batch_rtnl() to ->exit_rtnl().

2025-04-15T00:08:42+00:00

The following functions iterates the dying netns list and performs the same operations for each netns. * ip6gre_exit_batch_rtnl() * ip6_tnl_exit_batch_rtnl() * vti6_exit_batch_rtnl() * sit_exit_batch_rtnl() Let's use ->exit_rtnl(). Signed-off-by: Kuniyuki Iwashima Reviewed-by: David Ahern Reviewed-by: Sabrina Dubroca Link: https://patch.msgid.link/20250411205258.63164-8-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

net: move misc netdev_lock flavors to a separate header

2025-03-08T17:06:50+00:00

Move the more esoteric helpers for netdev instance lock to a dedicated header. This avoids growing netdevice.h to infinity and makes rebuilding the kernel much faster (after touching the header with the helpers). The main netdev_lock() / netdev_unlock() functions are used in static inlines in netdevice.h and will probably be used most commonly, so keep them in netdevice.h. Acked-by: Stanislav Fomichev Link: https://patch.msgid.link/20250307183006.2312761-1-kuba@kernel.org Signed-off-by: Jakub Kicinski

net: ipv6: Use link netns in newlink() of rtnl_link_ops

2025-02-21T23:28:02+00:00

When link_net is set, use it as link netns instead of dev_net(). This prepares for rtnetlink core to create device in target netns directly, in which case the two namespaces may be different. Signed-off-by: Xiao Liang Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250219125039.18024-9-shaw.leon@gmail.com Signed-off-by: Jakub Kicinski

net: ipv6: Init tunnel link-netns before registering dev

2025-02-21T23:28:02+00:00

Currently some IPv6 tunnel drivers set tnl->net to dev_net(dev) in ndo_init(), which is called in register_netdevice(). However, it lacks the context of link-netns when we enable cross-net tunnels at device registration time. Let's move the init of tunnel link-netns before register_netdevice(). ip6_gre has already initialized netns, so just remove the redundant assignment. Signed-off-by: Xiao Liang Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250219125039.18024-8-shaw.leon@gmail.com Signed-off-by: Jakub Kicinski