[strongSwan] ipv6ready IKEv2_Self_Test v1.0.3 failing with strongSwan

[Jiri Bohac]

Hi,

On Mon, Jul 26, 2010 at 09:45:05AM +0200, Martin Willi wrote:
> > However, strongSwan automatically uses any integrity algorithm
> > specified in a ike= proposal definition 
> 
> This is a limitation inherited from the configuration syntax for IKEv1.
> 
> I don't know if it makes sense for real setups

me neither. I don't know it you want to do this just for the sake
of passing ipv6ready one day. Why not...

>, but extending the syntax should be no problem. The question
> would be how we distinguish PRF and integrity algorithms in our
> proposal string (psha1,psha256?).

For testing purposes, I applied the following patch to
strongSwan. Any algorithm prefixed with "integrity_" will not
be automatically used for PRF and any algorithm prefixed with
"prf_" will not be used for integrity.

Thus, "ike=3des-integrity_sha1-prf_sha1-modp1024" is equivalent
to "ike=3des-sha1-modp1024".
"ike=3des,integrity_md5-prf-sha1-modp1024" will create a proposal
which you can not cpecify with the current syntax.

The patch (with appropriately tweaked TAHI remote scripts)
allowed quite a few of the failing tests to pass.

This could be more cleanly implemented defining new
new AUTH_ONLY_ALGORITHM_TYPE and PRF_ALGORITHM constants and
adding the new prefixed keywords to the hash table in
src/libstrongswan/crypto/proposal/proposal_keywords.txt
I used this patch to avoid having to re-run gperf after patching.


Index: strongswan-4.4.0/src/libcharon/config/proposal.c
===================================================================
--- strongswan-4.4.0.orig/src/libcharon/config/proposal.c	2010-07-26 12:32:46.000000000 +0200
+++ strongswan-4.4.0/src/libcharon/config/proposal.c	2010-07-26 13:58:24.000000000 +0200
@@ -588,18 +588,44 @@ static void check_proposal(private_propo
 /**
  * add a algorithm identified by a string to the proposal.
  */
+
+#define INTEGRITY_ONLY_PREFIX "integrity_"
+#define INTEGRITY_ONLY_PREFIX_LEN (sizeof(INTEGRITY_ONLY_PREFIX) - 1)
+#define PRF_ONLY_PREFIX "prf_"
+#define PRF_ONLY_PREFIX_LEN (sizeof(PRF_ONLY_PREFIX) - 1)
+
 static status_t add_string_algo(private_proposal_t *this, chunk_t alg)
 {
-	const proposal_token_t *token = proposal_get_token(alg.ptr, alg.len);
+	const proposal_token_t *token;
+	int integrity_only = 0, prf_only = 0;
+
+	/* algorithms prefixed with "integrity_" / "prf_" will not be automatically added as
+	   both integrity and PRF algorithms */
+	if (INTEGRITY_ONLY_PREFIX_LEN < alg.len &&
+		!strncmp(alg.ptr, INTEGRITY_ONLY_PREFIX, INTEGRITY_ONLY_PREFIX_LEN)) {
+		integrity_only = 1;
+		alg.ptr += INTEGRITY_ONLY_PREFIX_LEN;
+		alg.len -= INTEGRITY_ONLY_PREFIX_LEN;
+	}
+	else if (PRF_ONLY_PREFIX_LEN < alg.len &&
+		!strncmp(alg.ptr, PRF_ONLY_PREFIX, PRF_ONLY_PREFIX_LEN)) {
+		prf_only = 1;
+		alg.ptr += PRF_ONLY_PREFIX_LEN;
+		alg.len -= PRF_ONLY_PREFIX_LEN;
+	}
+
+	token = proposal_get_token(alg.ptr, alg.len);
 
 	if (token == NULL)
 	{
 		return FAILED;
 	}
 
-	add_algorithm(this, token->type, token->algorithm, token->keysize);
+	if (!prf_only)
+		add_algorithm(this, token->type, token->algorithm, token->keysize);
 
-	if (this->protocol == PROTO_IKE && token->type == INTEGRITY_ALGORITHM)
+	if (this->protocol == PROTO_IKE && token->type == INTEGRITY_ALGORITHM &&
+		!integrity_only)
 	{
 		pseudo_random_function_t prf;
 
Rgards,

-- 
Jiri Bohac <jbohac at suse.cz>
SUSE Labs, SUSE CZ