Linux-libre 4.2-gnu

1 files changed, 47 insertions, 17 deletions

diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index cc1da6d9c..921138f6c 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -75,6 +75,7 @@ struct ipq {
 	__be16		id;
 	u8		protocol;
 	u8		ecn; /* RFC3168 support */
+	u16		max_df_size; /* largest frag with DF set seen */
 	int             iif;
 	unsigned int    rid;
 	struct inet_peer *peer;
@@ -173,6 +174,15 @@ static void ipq_kill(struct ipq *ipq)
 	inet_frag_kill(&ipq->q, &ip4_frags);
 }
 
+static bool frag_expire_skip_icmp(u32 user)
+{
+	return user == IP_DEFRAG_AF_PACKET ||
+	       ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_IN,
+					 __IP_DEFRAG_CONNTRACK_IN_END) ||
+	       ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_BRIDGE_IN,
+					 __IP_DEFRAG_CONNTRACK_BRIDGE_IN);
+}
+
 /*
  * Oops, a fragment queue timed out.  Kill it and send an ICMP reply.
  */
@@ -192,7 +202,7 @@ static void ip_expire(unsigned long arg)
 	ipq_kill(qp);
 	IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS);
 
-	if (!(qp->q.flags & INET_FRAG_EVICTED)) {
+	if (!inet_frag_evicting(&qp->q)) {
 		struct sk_buff *head = qp->q.fragments;
 		const struct iphdr *iph;
 		int err;
@@ -217,10 +227,8 @@ static void ip_expire(unsigned long arg)
 		/* Only an end host needs to send an ICMP
 		 * "Fragment Reassembly Timeout" message, per RFC792.
 		 */
-		if (qp->user == IP_DEFRAG_AF_PACKET ||
-		    ((qp->user >= IP_DEFRAG_CONNTRACK_IN) &&
-		     (qp->user <= __IP_DEFRAG_CONNTRACK_IN_END) &&
-		     (skb_rtable(head)->rt_type != RTN_LOCAL)))
+		if (frag_expire_skip_icmp(qp->user) &&
+		    (skb_rtable(head)->rt_type != RTN_LOCAL))
 			goto out_rcu_unlock;
 
 		/* Send an ICMP "Fragment Reassembly Timeout" message. */
@@ -301,7 +309,7 @@ static int ip_frag_reinit(struct ipq *qp)
 		kfree_skb(fp);
 		fp = xp;
 	} while (fp);
-	sub_frag_mem_limit(&qp->q, sum_truesize);
+	sub_frag_mem_limit(qp->q.net, sum_truesize);
 
 	qp->q.flags = 0;
 	qp->q.len = 0;
@@ -319,6 +327,7 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 {
 	struct sk_buff *prev, *next;
 	struct net_device *dev;
+	unsigned int fragsize;
 	int flags, offset;
 	int ihl, end;
 	int err = -ENOENT;
@@ -342,7 +351,7 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 	ihl = ip_hdrlen(skb);
 
 	/* Determine the position of this fragment. */
-	end = offset + skb->len - ihl;
+	end = offset + skb->len - skb_network_offset(skb) - ihl;
 	err = -EINVAL;
 
 	/* Is this the final fragment? */
@@ -372,7 +381,7 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 		goto err;
 
 	err = -ENOMEM;
-	if (!pskb_pull(skb, ihl))
+	if (!pskb_pull(skb, skb_network_offset(skb) + ihl))
 		goto err;
 
 	err = pskb_trim_rcsum(skb, end - offset);
@@ -446,7 +455,7 @@ found:
 				qp->q.fragments = next;
 
 			qp->q.meat -= free_it->len;
-			sub_frag_mem_limit(&qp->q, free_it->truesize);
+			sub_frag_mem_limit(qp->q.net, free_it->truesize);
 			kfree_skb(free_it);
 		}
 	}
@@ -470,13 +479,18 @@ found:
 	qp->q.stamp = skb->tstamp;
 	qp->q.meat += skb->len;
 	qp->ecn |= ecn;
-	add_frag_mem_limit(&qp->q, skb->truesize);
+	add_frag_mem_limit(qp->q.net, skb->truesize);
 	if (offset == 0)
 		qp->q.flags |= INET_FRAG_FIRST_IN;
 
+	fragsize = skb->len + ihl;
+
+	if (fragsize > qp->q.max_size)
+		qp->q.max_size = fragsize;
+
 	if (ip_hdr(skb)->frag_off & htons(IP_DF) &&
-	    skb->len + ihl > qp->q.max_size)
-		qp->q.max_size = skb->len + ihl;
+	    fragsize > qp->max_df_size)
+		qp->max_df_size = fragsize;
 
 	if (qp->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) &&
 	    qp->q.meat == qp->q.len) {
@@ -573,7 +587,7 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
 		head->len -= clone->len;
 		clone->csum = 0;
 		clone->ip_summed = head->ip_summed;
-		add_frag_mem_limit(&qp->q, clone->truesize);
+		add_frag_mem_limit(qp->q.net, clone->truesize);
 	}
 
 	skb_push(head, head->data - skb_network_header(head));
@@ -601,18 +615,34 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
 		}
 		fp = next;
 	}
-	sub_frag_mem_limit(&qp->q, sum_truesize);
+	sub_frag_mem_limit(qp->q.net, sum_truesize);
 
 	head->next = NULL;
 	head->dev = dev;
 	head->tstamp = qp->q.stamp;
-	IPCB(head)->frag_max_size = qp->q.max_size;
+	IPCB(head)->frag_max_size = max(qp->max_df_size, qp->q.max_size);
 
 	iph = ip_hdr(head);
-	/* max_size != 0 implies at least one fragment had IP_DF set */
-	iph->frag_off = qp->q.max_size ? htons(IP_DF) : 0;
 	iph->tot_len = htons(len);
 	iph->tos |= ecn;
+
+	/* When we set IP_DF on a refragmented skb we must also force a
+	 * call to ip_fragment to avoid forwarding a DF-skb of size s while
+	 * original sender only sent fragments of size f (where f < s).
+	 *
+	 * We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest
+	 * frag seen to avoid sending tiny DF-fragments in case skb was built
+	 * from one very small df-fragment and one large non-df frag.
+	 */
+	if (qp->max_df_size == qp->q.max_size) {
+		IPCB(head)->flags |= IPSKB_FRAG_PMTU;
+		iph->frag_off = htons(IP_DF);
+	} else {
+		iph->frag_off = 0;
+	}
+
+	ip_send_check(iph);
+
 	IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS);
 	qp->q.fragments = NULL;
 	qp->q.fragments_tail = NULL;