Hi,
If interface drivers have enabled transmit offloading for the payload
checksum , IPv6 fragments contain invalid checksum. For fragments
the protocol checksum has to be calculated before fragmentation.
Hardware cannot do this as it is too late. Do it earlier in software.
ip_fragement() has such code, but in IPv6 it is missing. Note that
in6_proto_cksum_out() has to be called before the next protocol is
set to IPPROTO_FRAGMENT.
ok?
bluhm
Index: netinet6/ip6_output.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/ip6_output.c,v
retrieving revision 1.269
diff -u -p -r1.269 ip6_output.c
--- netinet6/ip6_output.c 29 Jun 2022 22:45:24 -0000 1.269
+++ netinet6/ip6_output.c 6 Aug 2022 22:21:04 -0000
@@ -729,6 +729,12 @@ reroute:
mtu = IPV6_MAXPACKET;
/*
+ * If we are doing fragmentation, we can't defer TCP/UDP
+ * checksumming; compute the checksum and clear the flag.
+ */
+ in6_proto_cksum_out(m, NULL);
+
+ /*
* Change the next header field of the last header in the
* unfragmentable part.
*/
