1 files changed, 67 insertions, 1 deletions

diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 8ce0ce2ee48e..ce2b70ce4018 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -22,6 +22,7 @@
  *		Patrick McHardy :	LRU queue of frag heads for evictor.
  */
 
+#include <linux/compiler.h>
 #include <linux/config.h>
 #include <linux/module.h>
 #include <linux/types.h>
@@ -38,6 +39,7 @@
 #include <net/ip.h>
 #include <net/icmp.h>
 #include <net/checksum.h>
+#include <net/inetpeer.h>
 #include <linux/tcp.h>
 #include <linux/udp.h>
 #include <linux/inet.h>
@@ -56,6 +58,8 @@
 int sysctl_ipfrag_high_thresh = 256*1024;
 int sysctl_ipfrag_low_thresh = 192*1024;
 
+int sysctl_ipfrag_max_dist = 64;
+
 /* Important NOTE! Fragment queue must be destroyed before MSL expires.
  * RFC791 is wrong proposing to prolongate timer each fragment arrival by TTL.
  */
@@ -89,8 +93,10 @@ struct ipq {
 	spinlock_t	lock;
 	atomic_t	refcnt;
 	struct timer_list timer;	/* when will this queue expire?		*/
-	int		iif;
 	struct timeval	stamp;
+	int             iif;
+	unsigned int    rid;
+	struct inet_peer *peer;
 };
 
 /* Hash table. */
@@ -195,6 +201,9 @@ static void ip_frag_destroy(struct ipq *qp, int *work)
 	BUG_TRAP(qp->last_in&COMPLETE);
 	BUG_TRAP(del_timer(&qp->timer) == 0);
 
+	if (qp->peer)
+		inet_putpeer(qp->peer);
+
 	/* Release all fragment data. */
 	fp = qp->fragments;
 	while (fp) {
@@ -353,6 +362,7 @@ static struct ipq *ip_frag_create(unsigned hash, struct iphdr *iph, u32 user)
 	qp->meat = 0;
 	qp->fragments = NULL;
 	qp->iif = 0;
+	qp->peer = sysctl_ipfrag_max_dist ? inet_getpeer(iph->saddr, 1) : NULL;
 
 	/* Initialize a timer for this entry. */
 	init_timer(&qp->timer);
@@ -398,6 +408,56 @@ static inline struct ipq *ip_find(struct iphdr *iph, u32 user)
 	return ip_frag_create(hash, iph, user);
 }
 
+/* Is the fragment too far ahead to be part of ipq? */
+static inline int ip_frag_too_far(struct ipq *qp)
+{
+	struct inet_peer *peer = qp->peer;
+	unsigned int max = sysctl_ipfrag_max_dist;
+	unsigned int start, end;
+
+	int rc;
+
+	if (!peer || !max)
+		return 0;
+
+	start = qp->rid;
+	end = atomic_inc_return(&peer->rid);
+	qp->rid = end;
+
+	rc = qp->fragments && (end - start) > max;
+
+	if (rc) {
+		IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS);
+	}
+
+	return rc;
+}
+
+static int ip_frag_reinit(struct ipq *qp)
+{
+	struct sk_buff *fp;
+
+	if (!mod_timer(&qp->timer, jiffies + sysctl_ipfrag_time)) {
+		atomic_inc(&qp->refcnt);
+		return -ETIMEDOUT;
+	}
+
+	fp = qp->fragments;
+	do {
+		struct sk_buff *xp = fp->next;
+		frag_kfree_skb(fp, NULL);
+		fp = xp;
+	} while (fp);
+
+	qp->last_in = 0;
+	qp->len = 0;
+	qp->meat = 0;
+	qp->fragments = NULL;
+	qp->iif = 0;
+
+	return 0;
+}
+
 /* Add new segment to existing queue. */
 static void ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 {
@@ -408,6 +468,12 @@ static void ip_frag_queue(struct ipq *qp, struct sk_buff *skb)
 	if (qp->last_in & COMPLETE)
 		goto err;
 
+	if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) &&
+	    unlikely(ip_frag_too_far(qp)) && unlikely(ip_frag_reinit(qp))) {
+		ipq_kill(qp);
+		goto err;
+	}
+
  	offset = ntohs(skb->nh.iph->frag_off);
 	flags = offset & ~IP_OFFSET;
 	offset &= IP_OFFSET;