ports/security/ipsec-tools/files/patch-isakmp_frag.c
Eugene Grosbein 4e95cbb248 security/ipsec-tools: fix CVE-2016-10396
The racoon daemon in IPsec-Tools 0.8.2 contains a remotely exploitable
computational-complexity attack when parsing and storing ISAKMP fragments.
The implementation permits a remote attacker to exhaust computational
resources on the remote endpoint by repeatedly sending ISAKMP fragment
packets in a particular order such that the worst-case computational
complexity is realized in the algorithm utilized to determine
if reassembly of the fragments can take place.

The fix obtained from NetBSD CVS head with a command:

cvs diff -D 2017-01-24 -D 2017-09-01 \
	src/racoon/handler.h \
	src/racoon/isakmp.c \
	src/racoon/isakmp_frag.c \
	src/racoon/isakmp_inf.c

While here, add LICENSE.

PR:		225066
Approved by:	VANHULLEBUS Yvan (maintainer timeout, 3 months)
Obtained from:	NetBSD
MFH:		2018Q1
Security:	CVE-2016-10396
2018-04-14 12:07:58 +00:00

151 lines
4 KiB
C

Index: src/racoon/isakmp_frag.c
===================================================================
RCS file: /cvsroot/src/crypto/dist/ipsec-tools/src/racoon/isakmp_frag.c,v
retrieving revision 1.5
retrieving revision 1.7
diff -p -u -r1.5 -r1.7
--- src/racoon/isakmp_frag.c 22 Apr 2009 11:24:20 -0000 1.5
+++ src/racoon/isakmp_frag.c 23 Jul 2017 05:40:27 -0000 1.7
@@ -1,4 +1,4 @@
-/* $NetBSD: isakmp_frag.c,v 1.5 2009/04/22 11:24:20 tteras Exp $ */
+/* $NetBSD: isakmp_frag.c,v 1.7 2017/07/23 05:40:27 christos Exp $ */
/* Id: isakmp_frag.c,v 1.4 2004/11/13 17:31:36 manubsd Exp */
@@ -173,6 +173,43 @@ vendorid_frag_cap(gen)
return ntohl(hp[MD5_DIGEST_LENGTH / sizeof(*hp)]);
}
+static int
+isakmp_frag_insert(struct ph1handle *iph1, struct isakmp_frag_item *item)
+{
+ struct isakmp_frag_item *pitem = NULL;
+ struct isakmp_frag_item *citem = iph1->frag_chain;
+
+ /* no frag yet, just insert at beginning of list */
+ if (iph1->frag_chain == NULL) {
+ iph1->frag_chain = item;
+ return 0;
+ }
+
+ do {
+ /* duplicate fragment number, abort (CVE-2016-10396) */
+ if (citem->frag_num == item->frag_num)
+ return -1;
+
+ /* need to insert before current item */
+ if (citem->frag_num > item->frag_num) {
+ if (pitem != NULL)
+ pitem->frag_next = item;
+ else
+ /* insert at the beginning of the list */
+ iph1->frag_chain = item;
+ item->frag_next = citem;
+ return 0;
+ }
+
+ pitem = citem;
+ citem = citem->frag_next;
+ } while (citem != NULL);
+
+ /* we reached the end of the list, insert */
+ pitem->frag_next = item;
+ return 0;
+}
+
int
isakmp_frag_extract(iph1, msg)
struct ph1handle *iph1;
@@ -224,39 +261,43 @@ isakmp_frag_extract(iph1, msg)
item->frag_next = NULL;
item->frag_packet = buf;
- /* Look for the last frag while inserting the new item in the chain */
- if (item->frag_last)
- last_frag = item->frag_num;
+ /* Check for the last frag before inserting the new item in the chain */
+ if (item->frag_last) {
+ /* if we have the last fragment, indices must match */
+ if (iph1->frag_last_index != 0 &&
+ item->frag_last != iph1->frag_last_index) {
+ plog(LLV_ERROR, LOCATION, NULL,
+ "Repeated last fragment index mismatch\n");
+ racoon_free(item);
+ vfree(buf);
+ return -1;
+ }
- if (iph1->frag_chain == NULL) {
- iph1->frag_chain = item;
- } else {
- struct isakmp_frag_item *current;
+ last_frag = iph1->frag_last_index = item->frag_num;
+ }
- current = iph1->frag_chain;
- while (current->frag_next) {
- if (current->frag_last)
- last_frag = item->frag_num;
- current = current->frag_next;
- }
- current->frag_next = item;
+ /* insert fragment into chain */
+ if (isakmp_frag_insert(iph1, item) == -1) {
+ plog(LLV_ERROR, LOCATION, NULL,
+ "Repeated fragment index mismatch\n");
+ racoon_free(item);
+ vfree(buf);
+ return -1;
}
- /* If we saw the last frag, check if the chain is complete */
+ /* If we saw the last frag, check if the chain is complete
+ * we have a sorted list now, so just walk through */
if (last_frag != 0) {
+ item = iph1->frag_chain;
for (i = 1; i <= last_frag; i++) {
- item = iph1->frag_chain;
- do {
- if (item->frag_num == i)
- break;
- item = item->frag_next;
- } while (item != NULL);
-
+ if (item->frag_num != i)
+ break;
+ item = item->frag_next;
if (item == NULL) /* Not found */
break;
}
- if (item != NULL) /* It is complete */
+ if (i > last_frag) /* It is complete */
return 1;
}
@@ -291,15 +332,9 @@ isakmp_frag_reassembly(iph1)
}
data = buf->v;
+ item = iph1->frag_chain;
for (i = 1; i <= frag_count; i++) {
- item = iph1->frag_chain;
- do {
- if (item->frag_num == i)
- break;
- item = item->frag_next;
- } while (item != NULL);
-
- if (item == NULL) {
+ if (item->frag_num != i) {
plog(LLV_ERROR, LOCATION, NULL,
"Missing fragment #%d\n", i);
vfree(buf);
@@ -308,6 +343,7 @@ isakmp_frag_reassembly(iph1)
}
memcpy(data, item->frag_packet->v, item->frag_packet->l);
data += item->frag_packet->l;
+ item = item->frag_next;
}
out: