From: Willem de Bruijn <willemb@google.com> Date: Mon, 24 Sep 2018 20:49:57 +0000 (-0400) Subject: flow_dissector: lookup netns by skb->sk if skb->dev is NULL X-Git-Tag: baikal/mips/sdk5.9~17461^2~258^2 X-Git-Url: https://git.baikalelectronics.ru/sdk/?a=commitdiff_plain;h=f83d422c274febcb0b30d6f8cc279af9dcdb88b1;p=kernel.git flow_dissector: lookup netns by skb->sk if skb->dev is NULL BPF flow dissectors are configured per network namespace. __skb_flow_dissect looks up the netns through dev_net(skb->dev). In some dissector paths skb->dev is NULL, such as for Unix sockets. In these cases fall back to looking up the netns by socket. Analyzing the codepaths leading to __skb_flow_dissect I did not find a case where both skb->dev and skb->sk are NULL. Warn and fall back to standard flow dissector if one is found. Fixes: 23513a901445 ("flow_dissector: implements flow dissector BPF hook") Reported-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Willem de Bruijn <willemb@google.com> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> --- diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index 5c5dd74b5b3b0..738c7562e1e07 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -714,7 +714,7 @@ bool __skb_flow_dissect(const struct sk_buff *skb, struct flow_dissector_key_vlan *key_vlan; enum flow_dissect_ret fdret; enum flow_dissector_key_id dissector_vlan = FLOW_DISSECTOR_KEY_MAX; - struct bpf_prog *attached; + struct bpf_prog *attached = NULL; int num_hdrs = 0; u8 ip_proto = 0; bool ret; @@ -755,8 +755,14 @@ bool __skb_flow_dissect(const struct sk_buff *skb, target_container); rcu_read_lock(); - attached = skb ? rcu_dereference(dev_net(skb->dev)->flow_dissector_prog) - : NULL; + if (skb) { + if (skb->dev) + attached = rcu_dereference(dev_net(skb->dev)->flow_dissector_prog); + else if (skb->sk) + attached = rcu_dereference(sock_net(skb->sk)->flow_dissector_prog); + else + WARN_ON_ONCE(1); + } if (attached) { /* Note that even though the const qualifier is discarded * throughout the execution of the BPF program, all changes(the