From d0e13a1488ad30dc3c2c9347b931cb10f892e3a4 Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Mon, 24 Sep 2018 16:49:57 -0400 Subject: 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: d58e468b1112 ("flow_dissector: implements flow dissector BPF hook") Reported-by: Eric Dumazet Signed-off-by: Willem de Bruijn Acked-by: Song Liu Signed-off-by: Daniel Borkmann --- net/core/flow_dissector.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) (limited to 'net') diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index 5c5dd74b5b3b..738c7562e1e0 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 -- cgit v1.2.3-59-g8ed1b