Split the checksum calculation for IPv6 like for IPv4:

Always calculate the pseudo-header checksum.
Complete the checksum if hardware offload is not available.

Parts originally from NetBSD; ok henning@

3 files changed, 80 insertions, 4 deletions

diff --git a/sys/netinet6/in6.h b/sys/netinet6/in6.h
index 83ba26eb5cd..7a17a3e9c8f 100644
--- a/sys/netinet6/in6.h
+++ b/sys/netinet6/in6.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: in6.h,v 1.69 2013/10/28 21:02:35 deraadt Exp $	*/
+/*	$OpenBSD: in6.h,v 1.70 2014/01/22 14:27:20 naddy Exp $	*/
 /*	$KAME: in6.h,v 1.83 2001/03/29 02:55:07 jinmei Exp $	*/
 
 /*
@@ -416,6 +416,54 @@ typedef	__socklen_t	socklen_t;	/* length type for network syscalls */
 #endif /* __BSD_VISIBLE */
 
 #ifdef _KERNEL
+/*
+ * in6_cksum_phdr:
+ *
+ *	Compute significant parts of the IPv6 checksum pseudo-header
+ *	for use in a delayed TCP/UDP checksum calculation.
+ *
+ *	Args:
+ *
+ *		src		Source IPv6 address
+ *		dst		Destination IPv6 address
+ *		len		htonl(proto-hdr-len)
+ *		nxt		htonl(next-proto-number)
+ *
+ *	NOTE: We expect the src and dst addresses to be 16-bit
+ *	aligned!
+ */
+static __inline u_int16_t __attribute__((__unused__))
+in6_cksum_phdr(const struct in6_addr *src, const struct in6_addr *dst,
+    u_int32_t len, u_int32_t nxt)
+{
+	u_int32_t sum = 0;
+	const u_int16_t *w;
+
+	w = (const u_int16_t *) src;
+	sum += w[0];
+	if (!IN6_IS_SCOPE_EMBED(src))
+		sum += w[1];
+	sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
+	sum += w[6]; sum += w[7];
+
+	w = (const u_int16_t *) dst;
+	sum += w[0];
+	if (!IN6_IS_SCOPE_EMBED(dst))
+		sum += w[1];
+	sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
+	sum += w[6]; sum += w[7];
+
+	sum += (u_int16_t)(len >> 16) + (u_int16_t)(len /*& 0xffff*/);
+
+	sum += (u_int16_t)(nxt >> 16) + (u_int16_t)(nxt /*& 0xffff*/);
+
+	sum = (u_int16_t)(sum >> 16) + (u_int16_t)(sum /*& 0xffff*/);
+
+	if (sum > 0xffff)
+		sum -= 0xffff;
+
+	return (sum);
+}
 
 extern	u_char inet6ctlerrmap[];
 extern	struct ifqueue ip6intrq;	/* IP6 packet input queue */
diff --git a/sys/netinet6/in6_cksum.c b/sys/netinet6/in6_cksum.c
index a98b2004b6d..00e35629071 100644
--- a/sys/netinet6/in6_cksum.c
+++ b/sys/netinet6/in6_cksum.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: in6_cksum.c,v 1.15 2008/06/11 19:00:50 mcbride Exp $	*/
+/*	$OpenBSD: in6_cksum.c,v 1.16 2014/01/22 14:27:20 naddy Exp $	*/
 /*	$KAME: in6_cksum.c,v 1.10 2000/12/03 00:53:59 itojun Exp $	*/
 
 /*
@@ -115,6 +115,10 @@ in6_cksum(struct mbuf *m, u_int8_t nxt, u_int32_t off, u_int32_t len)
 			m->m_pkthdr.len, off, len);
 	}
 
+	/* Skip pseudo-header if nxt == 0. */
+	if (nxt == 0)
+		 goto skip_phdr;
+
 	bzero(&uph, sizeof(uph));
 
 	/*
@@ -141,6 +145,7 @@ in6_cksum(struct mbuf *m, u_int8_t nxt, u_int32_t off, u_int32_t len)
 	sum += uph.phs[0];  sum += uph.phs[1];
 	sum += uph.phs[2];  sum += uph.phs[3];
 
+skip_phdr:
 	/*
 	 * Secondly calculate a summary of the first mbuf excluding offset.
 	 */
diff --git a/sys/netinet6/ip6_output.c b/sys/netinet6/ip6_output.c
index f547e635db8..2efda0435f3 100644
--- a/sys/netinet6/ip6_output.c
+++ b/sys/netinet6/ip6_output.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip6_output.c,v 1.150 2014/01/21 10:18:26 mpi Exp $	*/
+/*	$OpenBSD: ip6_output.c,v 1.151 2014/01/22 14:27:20 naddy Exp $	*/
 /*	$KAME: ip6_output.c,v 1.172 2001/03/25 09:55:56 itojun Exp $	*/
 
 /*
@@ -3211,7 +3211,7 @@ in6_delayed_cksum(struct mbuf *m, u_int8_t nxt)
 	if (offset <= 0 || nxtp != nxt)
 		/* If the desired next protocol isn't found, punt. */
 		return;
-	csum = (u_int16_t)(in6_cksum(m, nxt, offset, m->m_pkthdr.len - offset));
+	csum = (u_int16_t)(in6_cksum(m, 0, offset, m->m_pkthdr.len - offset));
 
 	switch (nxt) {
 	case IPPROTO_TCP:
@@ -3238,6 +3238,29 @@ in6_delayed_cksum(struct mbuf *m, u_int8_t nxt)
 void
 in6_proto_cksum_out(struct mbuf *m, struct ifnet *ifp)
 {
+	/* some hw and in6_delayed_cksum need the pseudo header cksum */
+	if (m->m_pkthdr.csum_flags &
+	    (M_TCP_CSUM_OUT|M_UDP_CSUM_OUT|M_ICMP_CSUM_OUT)) {
+		struct ip6_hdr *ip6;
+		int nxt, offset;
+		u_int16_t csum;
+
+		ip6 = mtod(m, struct ip6_hdr *);
+		offset = ip6_lasthdr(m, 0, IPPROTO_IPV6, &nxt);
+		csum = in6_cksum_phdr(&ip6->ip6_src, &ip6->ip6_dst,
+		    htonl(m->m_pkthdr.len - offset), htonl(nxt));
+		if (nxt == IPPROTO_TCP)
+			offset += offsetof(struct tcphdr, th_sum);
+		else if (nxt == IPPROTO_UDP)
+			offset += offsetof(struct udphdr, uh_sum);
+		else if (nxt == IPPROTO_ICMPV6)
+			offset += offsetof(struct icmp6_hdr, icmp6_cksum);
+		if ((offset + sizeof(u_int16_t)) > m->m_len)
+			m_copyback(m, offset, sizeof(csum), &csum, M_NOWAIT);
+		else
+			*(u_int16_t *)(mtod(m, caddr_t) + offset) = csum;
+	}
+
 	if (m->m_pkthdr.csum_flags & M_TCP_CSUM_OUT) {
 		if (!ifp || !(ifp->if_capabilities & IFCAP_CSUM_TCPv6) ||
 		    ifp->if_bridgeport != NULL) {