[IPV6]: Allow ipv6 fragmentation via ip6_xmit() when ipfragok is set.

include/net/ipv6.h

@@ -299,7 +299,8 @@ extern int			ipv6_rcv(struct sk_buff *skb,
 extern int			ip6_xmit(struct sock *sk,
 					 struct sk_buff *skb,
 					 struct flowi *fl,
-					 struct ipv6_txoptions *opt);
+					 struct ipv6_txoptions *opt,
+					 int ipfragok);
 
 extern int			ip6_nd_hdr(struct sock *sk,
 					   struct sk_buff *skb,

net/ipv6/ip6_output.c

@@ -196,7 +196,7 @@ static inline int ip6_maybe_reroute(struct sk_buff *skb)
  */
 
 int ip6_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
-	     struct ipv6_txoptions *opt)
+	     struct ipv6_txoptions *opt, int ipfragok)
 {
 	struct ipv6_pinfo *np = sk ? inet6_sk(sk) : NULL;
 	struct in6_addr *first_hop = &fl->fl6_dst;
@@ -258,13 +258,14 @@ int ip6_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
 	ipv6_addr_copy(&hdr->daddr, first_hop);
 
 	mtu = dst_pmtu(dst);
-	if (skb->len <= mtu) {
+	if ((skb->len <= mtu) || ipfragok) {
 		IP6_INC_STATS(Ip6OutRequests);
 		return NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, skb, NULL, dst->dev, ip6_maybe_reroute);
 	}
 
 	if (net_ratelimit())
 		printk(KERN_DEBUG "IPv6: sending pkt_too_big to self\n");
+	skb->dev = dst->dev;
 	icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu, skb->dev);
 	kfree_skb(skb);
 	return -EMSGSIZE;

net/ipv6/tcp_ipv6.c

@@ -939,7 +939,7 @@ static int tcp_v6_send_synack(struct sock *sk, struct open_request *req,
 					 csum_partial((char *)th, skb->len, skb->csum));
 
 		ipv6_addr_copy(&fl.fl6_dst, &req->af.v6_req.rmt_addr);
-		err = ip6_xmit(sk, skb, &fl, opt);
+		err = ip6_xmit(sk, skb, &fl, opt, 0);
 		if (err == NET_XMIT_CN)
 			err = 0;
 	}
@@ -1057,7 +1057,7 @@ static void tcp_v6_send_reset(struct sk_buff *skb)
 	buff->dst = ip6_route_output(NULL, &fl);
 
 	if (buff->dst->error == 0) {
-		ip6_xmit(NULL, buff, &fl, NULL);
+		ip6_xmit(NULL, buff, &fl, NULL, 0);
 		TCP_INC_STATS_BH(TcpOutSegs);
 		TCP_INC_STATS_BH(TcpOutRsts);
 		return;
@@ -1120,7 +1120,7 @@ static void tcp_v6_send_ack(struct sk_buff *skb, u32 seq, u32 ack, u32 win, u32
 	buff->dst = ip6_route_output(NULL, &fl);
 
 	if (buff->dst->error == 0) {
-		ip6_xmit(NULL, buff, &fl, NULL);
+		ip6_xmit(NULL, buff, &fl, NULL, 0);
 		TCP_INC_STATS_BH(TcpOutSegs);
 		return;
 	}
@@ -1823,7 +1823,7 @@ static int tcp_v6_xmit(struct sk_buff *skb, int ipfragok)
 	/* Restore final destination back after routing done */
 	ipv6_addr_copy(&fl.fl6_dst, &np->daddr);
 
-	return ip6_xmit(sk, skb, &fl, np->opt);
+	return ip6_xmit(sk, skb, &fl, np->opt, 0);
 }
 
 static void v6_addr2sockaddr(struct sock *sk, struct sockaddr * uaddr)

net/sctp/ipv6.c

@@ -176,7 +176,7 @@ static int sctp_v6_xmit(struct sk_buff *skb, struct sctp_transport *transport,
 
 	SCTP_INC_STATS(SctpOutSCTPPacks);
 
-	return ip6_xmit(sk, skb, &fl, np->opt);
+	return ip6_xmit(sk, skb, &fl, np->opt, ipfragok);
 }
 
 /* Returns the dst cache entry for the given source and destination ip