sctp: Perform software checksum if packet has to be fragmented.

[ Upstream commit d2dbbba77e95dff4b4f901fee236fef6d9552072 ]

IP/IPv6 fragmentation knows how to compute only TCP/UDP checksum.
This causes problems if SCTP packets has to be fragmented and
ipsummed has been set to PARTIAL due to checksum offload support.
This condition can happen when retransmitting after MTU discover,
or when INIT or other control chunks are larger then MTU.
Check for the rare fragmentation condition in SCTP and use software
checksum calculation in this case.

CC: Fan Du <fan.du@windriver.com>
Signed-off-by: Vlad Yasevich <vyasevich@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/net/sctp/output.c b/net/sctp/output.c
index 8d4eacf8b6da16bc6983ae6a57f6c235ebb0bf46..54bc011ed01e274b2bcc16f352f5ea9685201df3 100644 (file)
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -507,7 +507,7 @@ int sctp_packet_transmit(struct sctp_packet *packet)
         */
        if (!sctp_checksum_disable &&
            (!(dst->dev->features & (NETIF_F_NO_CSUM | NETIF_F_SCTP_CSUM)) ||
-            (dst_xfrm(dst) != NULL))) {
+            (dst_xfrm(dst) != NULL) || packet->ipfragok)) {
                __u32 crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len);
 
                /* 3) Put the resultant value into the checksum field in the