Revert my local not yet properly tested changes, that leaked in

with r235923.

1 files changed, 23 insertions, 16 deletions

diff --git a/sys/netgraph/ng_mppc.c b/sys/netgraph/ng_mppc.c
index 20b4bd0..6754be7 100644
--- a/sys/netgraph/ng_mppc.c
+++ b/sys/netgraph/ng_mppc.c
@@ -98,6 +98,15 @@ static MALLOC_DEFINE(M_NETGRAPH_MPPC, "netgraph_mppc", "netgraph mppc node");
 /* Key length */
 #define KEYLEN(b)		(((b) & MPPE_128) ? 16 : 8)
 
+/*
+ * When packets are lost with MPPE, we may have to re-key arbitrarily
+ * many times to 'catch up' to the new jumped-ahead sequence number.
+ * Since this can be expensive, we pose a limit on how many re-keyings
+ * we will do at one time to avoid a possible D.O.S. vulnerability.
+ * This should instead be a configurable parameter.
+ */
+#define MPPE_MAX_REKEY		1000
+
 /* MPPC packet header bits */
 #define MPPC_FLAG_FLUSHED	0x8000		/* xmitter reset state */
 #define MPPC_FLAG_RESTART	0x4000		/* compress history restart */
@@ -632,22 +641,20 @@ ng_mppc_decompress(node_p node, struct mbuf **datap)
 #endif
 #ifdef NETGRAPH_MPPC_ENCRYPTION
 		if ((d->cfg.bits & MPPE_BITS) != 0) {
-                       u_int rekey;
- 
-                       /* How many times are we going to have to re-key? */
-                       rekey = ((d->cfg.bits & MPPE_STATELESS) != 0) ?
-                           numLost : (numLost / (MPPE_UPDATE_MASK + 1));
-                       if (rekey > 1000)
-                               log(LOG_ERR, "%s: %d packets dropped, "
-				   "node [%x]\n", __func__, numLost,
-				   node->nd_ID);
-
-			/*
-			 * When packets are lost or re-ordered with MPPE,
-			 * we may have to re-key up to 0xfff times to 'catch
-			 * up' to the new jumped-ahead sequence number. Yep,
-			 * this is heavy, but what else can we do?
-			 */
+			u_int rekey;
+
+			/* How many times are we going to have to re-key? */
+			rekey = ((d->cfg.bits & MPPE_STATELESS) != 0) ?
+			    numLost : (numLost / (MPPE_UPDATE_MASK + 1));
+			if (rekey > MPPE_MAX_REKEY) {
+				log(LOG_ERR, "%s: too many (%d) packets"
+				    " dropped, disabling node %p!",
+				    __func__, numLost, node);
+				priv->recv.cfg.enable = 0;
+				goto failed;
+			}
+
+			/* Re-key as necessary to catch up to peer */
 			while (d->cc != cc) {
 				if ((d->cfg.bits & MPPE_STATELESS) != 0
 				    || (d->cc & MPPE_UPDATE_MASK)