convert the LDAP/SASL code to use GSS-SPNEGO if possible

we now do this:

- look for suported SASL mechanisms on the LDAP server
- choose GSS-SPNEGO if possible
- within GSS-SPNEGO choose KRB5 if we can do a kinit
- otherwise use NTLMSSP

This change also means that we no longer rely on having a gssapi
library to do ADS.

todo:
- add TLS/SSL support over LDAP
- change to using LDAP/SSL for password change in ADS
(This used to be commit b04e91f660d3b26d23044075d4a7e707eb41462d)

2 files changed, 221 insertions, 34 deletions

diff --git a/source3/libads/ldap.c b/source3/libads/ldap.c
index f0c4ad9040..2cfbedc6d4 100644
--- a/source3/libads/ldap.c
+++ b/source3/libads/ldap.c
@@ -226,7 +226,7 @@ ADS_STATUS ads_connect(ADS_STRUCT *ads)
 	/* try via DNS */
 	if (ads_try_dns(ads)) {
 		goto got_connection;
-		}
+	}
 
 	/* try via netbios lookups */
 	if (!lp_disable_netbios() && ads_try_netbios(ads)) {
@@ -274,11 +274,6 @@ got_connection:
 	}
 #endif
 
-	if (ads->auth.password) {
-		if ((code = ads_kinit_password(ads)))
-			return ADS_ERROR_KRB5(code);
-	}
-
 	if (ads->auth.no_bind) {
 		return ADS_SUCCESS;
 	}
diff --git a/source3/libads/sasl.c b/source3/libads/sasl.c
index 81dedb0a81..12a5722319 100644
--- a/source3/libads/sasl.c
+++ b/source3/libads/sasl.c
@@ -22,37 +22,192 @@
 
 #ifdef HAVE_ADS
 
-#if USE_CYRUS_SASL
-/*
-  this is a minimal interact function, just enough for SASL to talk
-  GSSAPI/kerberos to W2K
-  Error handling is a bit of a problem. I can't see how to get Cyrus-sasl
-  to give sensible errors
+/* 
+   perform a LDAP/SASL/SPNEGO/NTLMSSP bind (just how many layers can
+   we fit on one socket??)
 */
-static int sasl_interact(LDAP *ld,unsigned flags,void *defaults,void *in)
+static ADS_STATUS ads_sasl_spnego_ntlmssp_bind(ADS_STRUCT *ads)
 {
-	sasl_interact_t *interact = in;
+	const char *mechs[] = {OID_NTLMSSP, NULL};
+	DATA_BLOB msg1;
+	DATA_BLOB blob, chal1, chal2, auth;
+	uint8 challenge[8];
+	uint8 nthash[24], lmhash[24], sess_key[16];
+	uint32 neg_flags;
+	struct berval cred, *scred;
+	ADS_STATUS status;
+	extern pstring global_myname;
+	int rc;
+
+	neg_flags = NTLMSSP_NEGOTIATE_UNICODE | 
+		NTLMSSP_NEGOTIATE_128 | 
+		NTLMSSP_NEGOTIATE_NTLM;
+
+	memset(sess_key, 0, 16);
 
-	while (interact->id != SASL_CB_LIST_END) {
-		interact->result = strdup("");
-		interact->len = strlen(interact->result);
-		interact++;
+	/* generate the ntlmssp negotiate packet */
+	msrpc_gen(&blob, "CddB",
+		  "NTLMSSP",
+		  NTLMSSP_NEGOTIATE,
+		  neg_flags,
+		  sess_key, 16);
+
+	/* and wrap it in a SPNEGO wrapper */
+	msg1 = gen_negTokenTarg(mechs, blob);
+	data_blob_free(&blob);
+
+	cred.bv_val = msg1.data;
+	cred.bv_len = msg1.length;
+
+	rc = ldap_sasl_bind_s(ads->ld, NULL, "GSS-SPNEGO", &cred, NULL, NULL, &scred);
+	if (rc != LDAP_SASL_BIND_IN_PROGRESS) {
+		status = ADS_ERROR(rc);
+		goto failed;
 	}
-	
-	return LDAP_SUCCESS;
+
+	blob = data_blob(scred->bv_val, scred->bv_len);
+
+	/* the server gives us back two challenges */
+	if (!spnego_parse_challenge(blob, &chal1, &chal2)) {
+		DEBUG(3,("Failed to parse challenges\n"));
+		status = ADS_ERROR(LDAP_OPERATIONS_ERROR);
+		goto failed;
+	}
+
+	data_blob_free(&blob);
+
+	/* encrypt the password with the challenge */
+	memcpy(challenge, chal1.data + 24, 8);
+	SMBencrypt(ads->auth.password, challenge,lmhash);
+	SMBNTencrypt(ads->auth.password, challenge,nthash);
+
+	data_blob_free(&chal1);
+	data_blob_free(&chal2);
+
+	/* this generates the actual auth packet */
+	msrpc_gen(&blob, "CdBBUUUBd", 
+		  "NTLMSSP", 
+		  NTLMSSP_AUTH, 
+		  lmhash, 24,
+		  nthash, 24,
+		  lp_workgroup(), 
+		  ads->auth.user_name, 
+		  global_myname,
+		  sess_key, 16,
+		  neg_flags);
+
+	/* wrap it in SPNEGO */
+	auth = spnego_gen_auth(blob);
+
+	data_blob_free(&blob);
+
+	/* now send the auth packet and we should be done */
+	cred.bv_val = auth.data;
+	cred.bv_len = auth.length;
+
+	rc = ldap_sasl_bind_s(ads->ld, NULL, "GSS-SPNEGO", &cred, NULL, NULL, &scred);
+
+	return ADS_ERROR(rc);
+
+failed:
+	return status;
+}
+
+/* 
+   perform a LDAP/SASL/SPNEGO/KRB5 bind
+*/
+static ADS_STATUS ads_sasl_spnego_krb5_bind(ADS_STRUCT *ads, const char *principal)
+{
+	DATA_BLOB blob;
+	struct berval cred, *scred;
+	int rc;
+
+	blob = spnego_gen_negTokenTarg(principal);
+
+	if (!blob.data) {
+		return ADS_ERROR(LDAP_OPERATIONS_ERROR);
+	}
+
+	/* now send the auth packet and we should be done */
+	cred.bv_val = blob.data;
+	cred.bv_len = blob.length;
+
+	rc = ldap_sasl_bind_s(ads->ld, NULL, "GSS-SPNEGO", &cred, NULL, NULL, &scred);
+
+	data_blob_free(&blob);
+
+	return ADS_ERROR(rc);
 }
+
+/* 
+   this performs a SASL/SPNEGO bind
+*/
+static ADS_STATUS ads_sasl_spnego_bind(ADS_STRUCT *ads)
+{
+	struct berval *scred;
+	int rc, i;
+	ADS_STATUS status;
+	DATA_BLOB blob;
+	char *principal;
+	char *OIDs[ASN1_MAX_OIDS];
+	BOOL got_kerberos_mechanism = False;
+
+	rc = ldap_sasl_bind_s(ads->ld, NULL, "GSS-SPNEGO", NULL, NULL, NULL, &scred);
+
+	if (rc != LDAP_SASL_BIND_IN_PROGRESS) {
+		status = ADS_ERROR(rc);
+		goto failed;
+	}
+
+	blob = data_blob(scred->bv_val, scred->bv_len);
+
+#if 0
+	file_save("sasl_spnego.dat", blob.data, blob.length);
 #endif
 
+	/* the server sent us the first part of the SPNEGO exchange in the negprot 
+	   reply */
+	if (!spnego_parse_negTokenInit(blob, OIDs, &principal)) {
+		data_blob_free(&blob);
+		status = ADS_ERROR(LDAP_OPERATIONS_ERROR);
+		goto failed;
+	}
+	data_blob_free(&blob);
+
+	/* make sure the server understands kerberos */
+	for (i=0;OIDs[i];i++) {
+		DEBUG(3,("got OID=%s\n", OIDs[i]));
+		if (strcmp(OIDs[i], OID_KERBEROS5_OLD) == 0 ||
+		    strcmp(OIDs[i], OID_KERBEROS5) == 0) {
+			got_kerberos_mechanism = True;
+		}
+		free(OIDs[i]);
+	}
+	DEBUG(3,("got principal=%s\n", principal));
 
+	if (got_kerberos_mechanism && ads_kinit_password(ads) == 0) {
+		return ads_sasl_spnego_krb5_bind(ads, principal);
+	}
+
+	/* lets do NTLMSSP ... this has the big advantage that we don't need
+	   to sync clocks, and we don't rely on special versions of the krb5 
+	   library for HMAC_MD4 encryption */
+	return ads_sasl_spnego_ntlmssp_bind(ads);
+
+failed:
+	return status;
+}
+
+#ifdef HAVE_GSSAPI
 #define MAX_GSS_PASSES 3
 
 /* this performs a SASL/gssapi bind
    we avoid using cyrus-sasl to make Samba more robust. cyrus-sasl
    is very dependent on correctly configured DNS whereas
    this routine is much less fragile
-   see RFC2078 for details
+   see RFC2078 and RFC2222 for details
 */
-ADS_STATUS ads_sasl_gssapi_bind(ADS_STRUCT *ads)
+static ADS_STATUS ads_sasl_gssapi_bind(ADS_STRUCT *ads)
 {
 	int minor_status;
 	gss_name_t serv_name;
@@ -68,6 +223,7 @@ ADS_STATUS ads_sasl_gssapi_bind(ADS_STRUCT *ads)
 	uint8 *p;
 	uint32 max_msg_size;
 	char *sname;
+	unsigned sec_layer;
 	ADS_STATUS status;
 	krb5_principal principal;
 	krb5_context ctx;
@@ -159,22 +315,25 @@ ADS_STATUS ads_sasl_gssapi_bind(ADS_STRUCT *ads)
 
 	p = (uint8 *)output_token.value;
 
+	file_save("sasl_gssapi.dat", output_token.value, output_token.length);
+
 	max_msg_size = (p[1]<<16) | (p[2]<<8) | p[3];
+	sec_layer = *p;
 
 	gss_release_buffer(&minor_status, &output_token);
 
 	output_token.value = malloc(strlen(ads->config.bind_path) + 8);
 	p = output_token.value;
 
-	*p++ = 1; /* no sign or seal */
+	*p++ = 1; /* no sign & seal selection */
 	/* choose the same size as the server gave us */
 	*p++ = max_msg_size>>16;
 	*p++ = max_msg_size>>8;
 	*p++ = max_msg_size;
 	snprintf(p, strlen(ads->config.bind_path)+4, "dn:%s", ads->config.bind_path);
-	p += strlen(ads->config.bind_path);
+	p += strlen(p);
 
-	output_token.length = strlen(ads->config.bind_path) + 8;
+	output_token.length = PTR_DIFF(p, output_token.value);
 
 	gss_rc = gss_wrap(&minor_status, context_handle,0,GSS_C_QOP_DEFAULT,
 			  &output_token, &conf_state,
@@ -198,18 +357,51 @@ ADS_STATUS ads_sasl_gssapi_bind(ADS_STRUCT *ads)
 failed:
 	return status;
 }
+#endif
+
+/* mapping between SASL mechanisms and functions */
+static struct {
+	const char *name;
+	ADS_STATUS (*fn)(ADS_STRUCT *);
+} sasl_mechanisms[] = {
+	{"GSS-SPNEGO", ads_sasl_spnego_bind},
+#ifdef HAVE_GSSAPI
+	{"GSSAPI", ads_sasl_gssapi_bind}, /* doesn't work with .NET RC1. No idea why */
+#endif
+	{NULL, NULL}
+};
 
 ADS_STATUS ads_sasl_bind(ADS_STRUCT *ads)
 {
-#if USE_CYRUS_SASL
-	int rc;
-	rc = ldap_sasl_interactive_bind_s(ads->ld, NULL, NULL, NULL, NULL, 
-					  LDAP_SASL_QUIET,
-					  sasl_interact, NULL);
-	return ADS_ERROR(rc);
-#else
-	return ads_sasl_gssapi_bind(ads);
-#endif
+	const char *attrs[] = {"supportedSASLMechanisms", NULL};
+	char **values;
+	ADS_STATUS status;
+	int i, j;
+	void *res;
+
+	/* get a list of supported SASL mechanisms */
+	status = ads_do_search(ads, "", LDAP_SCOPE_BASE, "(objectclass=*)", attrs, &res);
+	if (!ADS_ERR_OK(status)) return status;
+
+	values = ldap_get_values(ads->ld, res, "supportedSASLMechanisms");
+
+	/* try our supported mechanisms in order */
+	for (i=0;sasl_mechanisms[i].name;i++) {
+		/* see if the server supports it */
+		for (j=0;values && values[j];j++) {
+			if (strcmp(values[j], sasl_mechanisms[i].name) == 0) {
+				DEBUG(4,("Found SASL mechanism %s\n", values[j]));
+				status = sasl_mechanisms[i].fn(ads);
+				ldap_value_free(values);
+				ldap_msgfree(res);
+				return status;
+			}
+		}
+	}
+
+	ldap_value_free(values);
+	ldap_msgfree(res);
+	return ADS_ERROR(LDAP_AUTH_METHOD_NOT_SUPPORTED);
 }
 
 #endif