On Wed, Apr 04, 2012 at 09:10:52AM -0700, Ben Pfaff wrote:
> On Wed, Apr 04, 2012 at 02:15:00PM +0900, Simon Horman wrote:
> > This hook is based on a hook of the same name provided by UDP. It provides
> > a way for to receive packets that have a TCP header but are not in fact
> > TCP. It is intended to be used by an implementation of the STT tunneling
> > protocol within Open vSwtich's datapath. A prototype of such an
> > implementation has been made.
> >
> > Signed-off-by: Simon Horman <ho...@verge.net.au>
>
> The comments still talk about UDP.
Ooops, here is a fresh version
[RFC] [linux kernel patch] Add TCP encap_rcv hook
This hook is based on a hook of the same name provided by UDP. It provides
a way for to receive packets that have a TCP header and treat them in some
alternate way.
It is intended to be used by an implementation of the STT tunneling
protocol within Open vSwtich's datapath. A prototype of such an
implementation has been made.
Signed-off-by: Simon Horman <ho...@verge.net.au>
---
v2
* Fix comment to refer to TCP rather than UDP
* Allow skb to continue traversing the stack if
the encap_rcv callback returns a positive value.
This is the same behaviour as the UDP hook.
---
include/linux/tcp.h | 5 +++++
net/ipv4/tcp_ipv4.c | 28 +++++++++++++++++++++++++++-
2 files changed, 32 insertions(+), 1 deletions(-)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 3c7ffdb..36e794b 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -472,6 +472,11 @@ struct tcp_sock {
* contains related tcp_cookie_transactions fields.
*/
struct tcp_cookie_values *cookie_values;
+
+ /* For encapsulation sockets. */
+ __u16 encap_type;
+ /* Hole */
+ int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
};
static inline struct tcp_sock *tcp_sk(const struct sock *sk)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index fd54c5f..ce56c6c 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1663,6 +1663,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
const struct iphdr *iph;
const struct tcphdr *th;
struct sock *sk;
+ struct tcp_sock *tp;
int ret;
struct net *net = dev_net(skb->dev);
@@ -1714,6 +1715,32 @@ process:
if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
goto discard_and_relse;
+
+ tp = tcp_sk(sk);
+
+ if (tp->encap_type) {
+ int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
+
+ /*
+ * This is an encapsulation socket so pass the skb to
+ * the socket's udp_encap_rcv() hook. Otherwise, just
+ * fall through and pass this up the TCP socket.
+ * up->encap_rcv() returns the following value:
+ * =0 if skb was successfully passed to the encap
+ * handler or was discarded by it.
+ * >0 if skb should be passed on to TCP.
+ * <0 if skb should be resubmitted as proto -N
+ */
+
+ /* if we're overly short, let UDP handle it */
+ encap_rcv = ACCESS_ONCE(tp->encap_rcv);
+ if (encap_rcv) {
+ int ret = encap_rcv(sk, skb);
+ if (ret <= 0)
+ return -ret;
+ }
+ }
+
nf_reset(skb);
if (sk_filter(sk, skb))
@@ -1725,7 +1752,6 @@ process:
ret = 0;
if (!sock_owned_by_user(sk)) {
#ifdef CONFIG_NET_DMA
- struct tcp_sock *tp = tcp_sk(sk);
if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
tp->ucopy.dma_chan = dma_find_channel(DMA_MEMCPY);
if (tp->ucopy.dma_chan)
--
1.7.9.1
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