Subject: [PATCHv2 1/2 ] {xfrm, sctp} Stick to software crc32 even if hardware is capable of that

From: Fan Du <[email-masked]>
Date: Fri, 11 Oct 2013 15:05:45 +0800

On 2013年10月10日 21:11, Neil Horman wrote:
> On Thu, Oct 10, 2013 at 01:51:36PM +0800, Fan Du wrote:
>> igb/ixgbe have hardware sctp checksum support, when this feature is enabled
>> and also IPsec is armed to protect sctp traffic, ugly things happened as
>> xfrm_output checks CHECKSUM_PARTIAL to do check sum operation(sum every thing
>> up and pack the 16bits result in the checksum field). The result is fail
>> establishment of sctp communication.
>>
> Shouldn't this be fixed in the xfrm code then?  E.g. check the device features
> for SCTP checksum offloading and and skip the checksum during xfrm output if its
> available?
>
> Or am I missing something?
> Neil
>
>

 From 014276de0877f11d46e1704114a7d91f19221a63 Mon Sep 17 00:00:00 2001
From: Fan Du <[email-masked]>
Date: Fri, 11 Oct 2013 14:24:33 +0800
Subject: [PATCH 1/2] {xfrm, sctp} Stick to software crc32 even if hardware is
  capable of that

igb/ixgbe have hardware sctp checksum support, when this feature is enabled
and also IPsec is armed to protect sctp traffic, ugly things happened as
xfrm_output checks CHECKSUM_PARTIAL to do check sum operation(sum every thing
up and pack the 16bits result in the checksum field). The result is fail
establishment of sctp communication.

Signed-off-by: Fan Du <[email-masked]>
---
v2:
   Leave ip_summed as CHECKSUM_PARTIAL as before, the second patch will fix this.

---
  net/sctp/output.c |   14 +++++++++++++-
  1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/net/sctp/output.c b/net/sctp/output.c
index 0ac3a65..6de6402 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -372,6 +372,16 @@ static void sctp_packet_set_owner_w(struct sk_buff *skb, struct sock *sk)
  	atomic_inc(&sk->sk_wmem_alloc);
  }

+static int is_xfrm_armed(struct dst_entry *dst)
+{
+#ifdef CONFIG_XFRM
+	/* If dst->xfrm is valid, this skb needs to be transformed */
+	return dst->xfrm != NULL;
+#else
+	return 0;
+#endif
+}
+
  /* All packets are sent to the network through this function from
   * sctp_outq_tail().
   *
@@ -536,7 +546,9 @@ int sctp_packet_transmit(struct sctp_packet *packet)
  	 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
  	 */
  	if (!sctp_checksum_disable) {
-		if (!(dst->dev->features & NETIF_F_SCTP_CSUM)) {
+		if ((!(dst->dev->features & NETIF_F_SCTP_CSUM)) ||
+			is_xfrm_armed(dst)) {
+
  			__u32 crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len);

  			/* 3) Put the resultant value into the checksum field in the
-- 
1.7.9.5

-- 
浮沉随浪只记今朝笑

--fan