On Thu, 2016-11-10 at 11:26 -0800, Eric Dumazet wrote:
> The issue is that sk_filter() truncates an incoming packet to a smaller
> value.
>
> Bad things happen because TCP_SKB_CB(skb)->end_seq is not updated.
>
> I guess other issues would also happen if the truncation also removes
> part of tcp header.
>
> sk_filter_trim_cap(sk, skb, tcp_hlen) would be needed,
> or sk_filter_trim_cap(sk, skb, skb->len) to only ACCEPT/DROP packets,
> but no truncations.
Something like :
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 61b7be303eec..0b8f575eefaa 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1676,7 +1676,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
nf_reset(skb);
- if (sk_filter(sk, skb))
+ if (sk_filter_trim_cap(sk, skb, skb->len))
goto discard_and_relse;
skb->dev = NULL;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 6ca23c2e76f7..2c7a6f7f1113 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1229,7 +1229,7 @@ static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff
*skb)
if (skb->protocol == htons(ETH_P_IP))
return tcp_v4_do_rcv(sk, skb);
- if (sk_filter(sk, skb))
+ if (sk_filter_trim_cap(sk, skb, skb->len))
goto discard;
/*
