tcp: don't annotate mark on control socket from tcp_v6_send_response()

Unlike ipv4, this control socket is shared by all cpus so we cannot use
it as scratchpad area to annotate the mark that we pass to ip6_xmit().

Add a new parameter to ip6_xmit() to indicate the mark. The SCTP socket
family caches the flowi6 structure in the sctp_transport structure, so
we cannot use to carry the mark unless we later on reset it back, which
I discarded since it looks ugly to me.

Fixes: bf99b4ded5f8 ("tcp: fix mark propagation with fwmark_reflect enabled")
Suggested-by: Eric Dumazet <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/ipv6.h

···
  *	upper-layer output functions
  */
 int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
-	     struct ipv6_txoptions *opt, int tclass);
+	     __u32 mark, struct ipv6_txoptions *opt, int tclass);
 
 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr);
 

net/dccp/ipv6.c

···
 		opt = ireq->ipv6_opt;
 		if (!opt)
 			opt = rcu_dereference(np->opt);
-		err = ip6_xmit(sk, skb, &fl6, opt, np->tclass);
+		err = ip6_xmit(sk, skb, &fl6, sk->sk_mark, opt, np->tclass);
 		rcu_read_unlock();
 		err = net_xmit_eval(err);
 	}
···
 	dst = ip6_dst_lookup_flow(ctl_sk, &fl6, NULL);
 	if (!IS_ERR(dst)) {
 		skb_dst_set(skb, dst);
-		ip6_xmit(ctl_sk, skb, &fl6, NULL, 0);
+		ip6_xmit(ctl_sk, skb, &fl6, 0, NULL, 0);
 		DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
 		DCCP_INC_STATS(DCCP_MIB_OUTRSTS);
 		return;

net/ipv6/inet6_connection_sock.c

···
 	/* Restore final destination back after routing done */
 	fl6.daddr = sk->sk_v6_daddr;
 
-	res = ip6_xmit(sk, skb, &fl6, rcu_dereference(np->opt),
+	res = ip6_xmit(sk, skb, &fl6, sk->sk_mark, rcu_dereference(np->opt),
 		       np->tclass);
 	rcu_read_unlock();
 	return res;

net/ipv6/ip6_output.c

···
  * which are using proper atomic operations or spinlocks.
  */
 int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
-	     struct ipv6_txoptions *opt, int tclass)
+	     __u32 mark, struct ipv6_txoptions *opt, int tclass)
 {
 	struct net *net = sock_net(sk);
 	const struct ipv6_pinfo *np = inet6_sk(sk);
···
 
 	skb->protocol = htons(ETH_P_IPV6);
 	skb->priority = sk->sk_priority;
-	skb->mark = sk->sk_mark;
+	skb->mark = mark;
 
 	mtu = dst_mtu(dst);
 	if ((skb->len <= mtu) || skb->ignore_df || skb_is_gso(skb)) {

net/ipv6/tcp_ipv6.c

···
 		opt = ireq->ipv6_opt;
 		if (!opt)
 			opt = rcu_dereference(np->opt);
-		err = ip6_xmit(sk, skb, fl6, opt, np->tclass);
+		err = ip6_xmit(sk, skb, fl6, sk->sk_mark, opt, np->tclass);
 		rcu_read_unlock();
 		err = net_xmit_eval(err);
 	}
···
 	dst = ip6_dst_lookup_flow(ctl_sk, &fl6, NULL);
 	if (!IS_ERR(dst)) {
 		skb_dst_set(buff, dst);
-		ctl_sk->sk_mark = fl6.flowi6_mark;
-		ip6_xmit(ctl_sk, buff, &fl6, NULL, tclass);
+		ip6_xmit(ctl_sk, buff, &fl6, fl6.flowi6_mark, NULL, tclass);
 		TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
 		if (rst)
 			TCP_INC_STATS(net, TCP_MIB_OUTRSTS);

net/sctp/ipv6.c

···
 	SCTP_INC_STATS(sock_net(sk), SCTP_MIB_OUTSCTPPACKS);
 
 	rcu_read_lock();
-	res = ip6_xmit(sk, skb, fl6, rcu_dereference(np->opt), np->tclass);
+	res = ip6_xmit(sk, skb, fl6, sk->sk_mark, rcu_dereference(np->opt),
+		       np->tclass);
 	rcu_read_unlock();
 	return res;
 }