[ovs-dev] [PATCH] [RFC] [linux kernel patch] Add TCP encap_rcv hook
Simon Horman
horms at verge.net.au
Wed Apr 4 05:15:00 UTC 2012
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 <horms at verge.net.au>
---
include/linux/tcp.h | 5 +++++
net/ipv4/tcp_ipv4.c | 25 ++++++++++++++++++++++++-
2 files changed, 29 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..6d55863 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 +1715,29 @@ 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 UDP 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 UDP.
+ * <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)
+ return encap_rcv(sk, skb);
+ }
+
nf_reset(skb);
if (sk_filter(sk, skb))
@@ -1725,7 +1749,6 @@ 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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