From: Willem de Bruijn <will...@google.com>
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 <eduma...@google.com>
Signed-off-by: Willem de Bruijn <will...@google.com>
---
net/core/flow_dissector.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
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
--
2.19.0.444.g18242da7ef-goog
