From d8f703112e39ab0d58bc140d2f8db80add02acf7 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Fri, 22 Nov 2013 10:31:29 +0800 Subject: [PATCH] gro: Only verify TCP checksums for candidates [ Upstream commit cc5c00bbb44c5d68b883aa5cb9d01514a2525d94 ] In some cases we may receive IP packets that are longer than their stated lengths. Such packets are never merged in GRO. However, we may end up computing their checksums incorrectly and end up allowing packets with a bogus checksum enter our stack with the checksum status set as verified. Since such packets are rare and not performance-critical, this patch simply skips the checksum verification for them. Reported-by: Alexander Duyck Signed-off-by: Herbert Xu Acked-by: Alexander Duyck Thanks, Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_offload.c | 5 +++++ net/ipv6/tcpv6_offload.c | 5 +++++ 2 files changed, 10 insertions(+) diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c index 533c58a..44c8678 100644 --- a/net/ipv4/tcp_offload.c +++ b/net/ipv4/tcp_offload.c @@ -274,6 +274,10 @@ static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff * __wsum wsum; __sum16 sum; + /* Don't bother verifying checksum if we're going to flush anyway. */ + if (NAPI_GRO_CB(skb)->flush) + goto skip_csum; + switch (skb->ip_summed) { case CHECKSUM_COMPLETE: if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr, @@ -299,6 +303,7 @@ flush: break; } +skip_csum: return tcp_gro_receive(head, skb); } diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c index 2ec6bf6..78081d8 100644 --- a/net/ipv6/tcpv6_offload.c +++ b/net/ipv6/tcpv6_offload.c @@ -39,6 +39,10 @@ static struct sk_buff **tcp6_gro_receive(struct sk_buff **head, __wsum wsum; __sum16 sum; + /* Don't bother verifying checksum if we're going to flush anyway. */ + if (NAPI_GRO_CB(skb)->flush) + goto skip_csum; + switch (skb->ip_summed) { case CHECKSUM_COMPLETE: if (!tcp_v6_check(skb_gro_len(skb), &iph->saddr, &iph->daddr, @@ -65,6 +69,7 @@ flush: break; } +skip_csum: return tcp_gro_receive(head, skb); } -- 2.7.4