1 files changed, 27 insertions, 8 deletions

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 251ec12517e9..0872df066a4e 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -106,7 +106,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
 	if (lwtunnel_xmit_redirect(dst->lwtstate)) {
 		int res = lwtunnel_xmit(skb);
 
-		if (res < 0 || res == LWTUNNEL_XMIT_DONE)
+		if (res != LWTUNNEL_XMIT_CONTINUE)
 			return res;
 	}
 
@@ -153,7 +153,13 @@ ip6_finish_output_gso_slowpath_drop(struct net *net, struct sock *sk,
 		int err;
 
 		skb_mark_not_on_list(segs);
-		err = ip6_fragment(net, sk, segs, ip6_finish_output2);
+		/* Last GSO segment can be smaller than gso_size (and MTU).
+		 * Adding a fragment header would produce an "atomic fragment",
+		 * which is considered harmful (RFC-8021). Avoid that.
+		 */
+		err = segs->len > mtu ?
+			ip6_fragment(net, sk, segs, ip6_finish_output2) :
+			ip6_finish_output2(net, sk, segs);
 		if (err && ret == 0)
 			ret = err;
 	}
@@ -460,7 +466,7 @@ int ip6_forward(struct sk_buff *skb)
 		goto drop;
 
 	if (!net->ipv6.devconf_all->disable_policy &&
-	    !idev->cnf.disable_policy &&
+	    (!idev || !idev->cnf.disable_policy) &&
 	    !xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) {
 		__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
 		goto drop;
@@ -734,6 +740,9 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 		ipv6_hdr(skb)->payload_len = htons(first_len -
 						   sizeof(struct ipv6hdr));
 
+		/* We prevent @rt from being freed. */
+		rcu_read_lock();
+
 		for (;;) {
 			/* Prepare header of the next frame,
 			 * before previous one went down. */
@@ -776,6 +785,7 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 		if (err == 0) {
 			IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
 				      IPSTATS_MIB_FRAGOKS);
+			rcu_read_unlock();
 			return 0;
 		}
 
@@ -783,6 +793,7 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 
 		IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
 			      IPSTATS_MIB_FRAGFAILS);
+		rcu_read_unlock();
 		return err;
 
 slow_path_clean:
@@ -1259,8 +1270,6 @@ static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork,
 		if (np->frag_size)
 			mtu = np->frag_size;
 	}
-	if (mtu < IPV6_MIN_MTU)
-		return -EINVAL;
 	cork->base.fragsize = mtu;
 	cork->base.gso_size = ipc6->gso_size;
 	cork->base.tx_flags = 0;
@@ -1320,8 +1329,6 @@ static int __ip6_append_data(struct sock *sk,
 
 	fragheaderlen = sizeof(struct ipv6hdr) + rt->rt6i_nfheader_len +
 			(opt ? opt->opt_nflen : 0);
-	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen -
-		     sizeof(struct frag_hdr);
 
 	headersize = sizeof(struct ipv6hdr) +
 		     (opt ? opt->opt_flen + opt->opt_nflen : 0) +
@@ -1329,6 +1336,13 @@ static int __ip6_append_data(struct sock *sk,
 		      sizeof(struct frag_hdr) : 0) +
 		     rt->rt6i_nfheader_len;
 
+	if (mtu <= fragheaderlen ||
+	    ((mtu - fragheaderlen) & ~7) + fragheaderlen <= sizeof(struct frag_hdr))
+		goto emsgsize;
+
+	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen -
+		     sizeof(struct frag_hdr);
+
 	/* as per RFC 7112 section 5, the entire IPv6 Header Chain must fit
 	 * the first fragment
 	 */
@@ -1722,8 +1736,13 @@ struct sk_buff *__ip6_make_skb(struct sock *sk,
 	IP6_UPD_PO_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUT, skb->len);
 	if (proto == IPPROTO_ICMPV6) {
 		struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));
+		u8 icmp6_type;
 
-		ICMP6MSGOUT_INC_STATS(net, idev, icmp6_hdr(skb)->icmp6_type);
+		if (sk->sk_socket->type == SOCK_RAW && !inet_sk(sk)->hdrincl)
+			icmp6_type = fl6->fl6_icmp_type;
+		else
+			icmp6_type = icmp6_hdr(skb)->icmp6_type;
+		ICMP6MSGOUT_INC_STATS(net, idev, icmp6_type);
 		ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTMSGS);
 	}