bugtraq - Re: unauthorized deletion of IPsec (and ISAKMP) SAs in racoon

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Date: Wed, 14 Jan 2004 18:26:26 +0900 (JST)
From: itojun@...e.net
To: thomas@...nknerd.org
Cc: bugtraq@...urityfocus.com
Subject: Re: unauthorized deletion of IPsec (and ISAKMP) SAs in racoon


> 0 Preface
> 
>   Now that most bugs in isakmpd that allowed for unauthorized SA
>   deletion are "fixed", it's time to release some information on racoon.
> 
>   By the way: About 5 months ago I tried to contact the KAME developers.

	sorry that we did not take necessary actions that time.  the attached
	patch should remedy the problem (credit: IIJ SEIL team).
	kame as well as netbsd repository are updated, and vendors are informed.

itojun


Index: isakmp_inf.c
===================================================================
RCS file: /cvsroot/kame/kame/kame/kame/racoon/isakmp_inf.c,v
retrieving revision 1.82
diff -u -r1.82 isakmp_inf.c
--- isakmp_inf.c	13 Nov 2003 02:30:20 -0000	1.82
+++ isakmp_inf.c	14 Jan 2004 09:14:31 -0000
@@ -136,10 +136,81 @@
 
 	isakmp = (struct isakmp *)msg->v;
 	gen = (struct isakmp_gen *)((caddr_t)isakmp + sizeof(struct isakmp));
-	if (isakmp->np == ISAKMP_NPTYPE_HASH)
-		np = gen->np;
-	else
-		np = isakmp->np;
+
+	if (isakmp->np != ISAKMP_NPTYPE_HASH) {
+		plog(LLV_ERROR, LOCATION, NULL,
+		    "ignore information because the message has no hash payload.\n");
+		goto end;
+	}
+
+	if (iph1->status != PHASE1ST_ESTABLISHED) {
+		plog(LLV_ERROR, LOCATION, NULL,
+		    "ignore information because ISAKMP-SA has not been established yet.\n");
+		goto end;
+	}
+
+	np = gen->np;
+
+	{
+		void *p;
+		vchar_t *hash, *payload;
+		struct isakmp_gen *nd;
+
+		/*
+		 * XXX: gen->len includes isakmp header length
+		 */
+		p = (caddr_t) gen + sizeof(struct isakmp_gen);
+		nd = (struct isakmp_gen *) ((caddr_t) gen + gen->len);
+
+		/* nd length check */
+		if (nd->len > msg->l - (sizeof(struct isakmp) + gen->len)) {
+			plog(LLV_ERROR, LOCATION, NULL,
+				 "too long payload length (broken message?)\n");
+			goto end;
+		}
+
+		payload = vmalloc(nd->len);
+		if (payload == NULL) {
+			plog(LLV_ERROR, LOCATION, NULL,
+			    "cannot allocate memory\n");
+			goto end;
+		}
+
+		memcpy(payload->v, (caddr_t) nd, nd->len);
+
+		/* compute HASH */
+		hash = oakley_compute_hash1(iph1, isakmp->msgid, payload);
+		if (hash == NULL) {
+			plog(LLV_ERROR, LOCATION, NULL,
+			    "cannot compute hash\n");
+
+			vfree(payload);
+			goto end;
+		}
+		
+		if (gen->len - sizeof(struct isakmp_gen) != hash->l) {
+			plog(LLV_ERROR, LOCATION, NULL,
+			    "ignore information due to hash length mismatch\n");
+
+			vfree(hash);
+			vfree(payload);
+			goto end;
+		}
+
+		if (memcmp(p, hash->v, hash->l) != 0) {
+			plog(LLV_ERROR, LOCATION, NULL,
+			    "ignore information due to hash mismatch\n");
+
+			vfree(hash);
+			vfree(payload);
+			goto end;
+		}
+
+		plog(LLV_DEBUG, LOCATION, NULL, "hash validated.\n");
+
+		vfree(hash);
+		vfree(payload);
+	}
 		
 	/* make sure the packet were encrypted. */
 	if (!encrypted) {