From: Paul Durrant <paul.durrant@citrix•com>
To: <xen-devel@lists•xen.org>, <netdev@vger•kernel.org>
Cc: Paul Durrant <paul.durrant@citrix•com>,
Wei Liu <wei.liu2@citrix•com>,
Ian Campbell <ian.campbell@citrix•com>,
David Vrabel <david.vrabel@citrix•com>
Subject: [PATCH net v2] xen-netback: fix fragment detection in checksum setup
Date: Thu, 28 Nov 2013 13:23:52 +0000 [thread overview]
Message-ID: <1385645032-29848-1-git-send-email-paul.durrant@citrix.com> (raw)
The code to detect fragments in checksum_setup() was missing for IPv4 and
too eager for IPv6. (It transpires that Windows seems to send IPv6 packets
with a fragment header even if they are not a fragment - i.e. offset is zero,
and M bit is not set).
Signed-off-by: Paul Durrant <paul.durrant@citrix•com>
Cc: Wei Liu <wei.liu2@citrix•com>
Cc: Ian Campbell <ian.campbell@citrix•com>
Cc: David Vrabel <david.vrabel@citrix•com>
---
v2
- Added comments noting what fragment/offset masks mean
drivers/net/xen-netback/netback.c | 33 ++++++++++++++++++++++++++++++---
1 file changed, 30 insertions(+), 3 deletions(-)
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 919b650..c7464d8 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -1165,15 +1165,28 @@ static int checksum_setup_ip(struct xenvif *vif, struct sk_buff *skb,
struct iphdr *iph = (void *)skb->data;
unsigned int header_size;
unsigned int off;
+ bool fragment;
int err = -EPROTO;
+ fragment = false;
+
off = sizeof(struct iphdr);
header_size = skb->network_header + off + MAX_IPOPTLEN;
maybe_pull_tail(skb, header_size);
+ /* 3fff -> fragment offset != 0 OR more fragments */
+ if (ntohs(iph->frag_off) & 0x3fff)
+ fragment = true;
+
off = iph->ihl * 4;
+ if (fragment) {
+ if (net_ratelimit())
+ netdev_err(vif->dev, "Packet is a fragment!\n");
+ goto out;
+ }
+
switch (iph->protocol) {
case IPPROTO_TCP:
if (!skb_partial_csum_set(skb, off,
@@ -1237,6 +1250,7 @@ static int checksum_setup_ipv6(struct xenvif *vif, struct sk_buff *skb,
bool fragment;
bool done;
+ fragment = false;
done = false;
off = sizeof(struct ipv6hdr);
@@ -1275,9 +1289,22 @@ static int checksum_setup_ipv6(struct xenvif *vif, struct sk_buff *skb,
off += (hp->hdrlen+2)<<2;
break;
}
- case IPPROTO_FRAGMENT:
- fragment = true;
- /* fall through */
+ case IPPROTO_FRAGMENT: {
+ struct frag_hdr *hp = (void *)(skb->data + off);
+
+ header_size = skb->network_header +
+ off +
+ sizeof(struct frag_hdr);
+ maybe_pull_tail(skb, header_size);
+
+ /* fff9 -> fragment offset != 0 OR more fragments */
+ if (ntohs(hp->frag_off) & 0xfff9)
+ fragment = true;
+
+ nexthdr = hp->nexthdr;
+ off += sizeof(struct frag_hdr);
+ break;
+ }
default:
done = true;
break;
--
1.7.10.4
next reply other threads:[~2013-11-28 13:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-28 13:23 Paul Durrant [this message]
2013-11-28 17:29 ` [PATCH net v2] xen-netback: fix fragment detection in checksum setup Eric Dumazet
2013-11-29 10:32 ` Paul Durrant
2013-11-29 5:35 ` annie li
2013-11-29 9:10 ` Paul Durrant
2013-11-29 9:57 ` [Xen-devel] " annie li
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