netdev - [PATCH net-next] gro: should aggregate frames without DF

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <1370019752.5109.108.camel@edumazet-glaptop>
Date:	Fri, 31 May 2013 10:02:32 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>, Jerry Chu <hkchu@...gle.com>,
	Herbert Xu <herbert@...dor.apana.org.au>
Subject: [PATCH net-next] gro: should aggregate frames without DF

From: Eric Dumazet <edumazet@...gle.com>

GRO on IPv4 doesn't aggregate frames if they don't have DF bit set.

Some servers use IP_MTU_DISCOVER/IP_PMTUDISC_PROBE, so linux receivers
are unable to aggregate this kind of traffic.

The right thing to do is to allow aggregation as long as the DF bit has
same value on all segments.

bnx2x LRO does this correctly.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Jerry Chu <hkchu@...gle.com>
Cc: Herbert Xu <herbert@...dor.apana.org.au>
---
 net/ipv4/af_inet.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index b05ae96..328cc62 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1384,9 +1384,9 @@ static struct sk_buff **inet_gro_receive(struct sk_buff **head,
 	if (unlikely(ip_fast_csum((u8 *)iph, 5)))
 		goto out_unlock;
 
-	id = ntohl(*(__be32 *)&iph->id);
-	flush = (u16)((ntohl(*(__be32 *)iph) ^ skb_gro_len(skb)) | (id ^ IP_DF));
-	id >>= 16;
+	flush = ntohs(iph->tot_len) ^ skb_gro_len(skb);
+
+	id = ntohs(iph->id);
 
 	for (p = *head; p; p = p->next) {
 		struct iphdr *iph2;
@@ -1407,6 +1407,7 @@ static struct sk_buff **inet_gro_receive(struct sk_buff **head,
 		NAPI_GRO_CB(p)->flush |=
 			(iph->ttl ^ iph2->ttl) |
 			(iph->tos ^ iph2->tos) |
+			((iph->frag_off ^ iph2->frag_off) & htons(IP_DF)) |
 			((u16)(ntohs(iph2->id) + NAPI_GRO_CB(p)->count) ^ id);
 
 		NAPI_GRO_CB(p)->flush |= flush;


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html