Merge pull request #110 from cg2v/anonymous-pkinit

Anonymous pkinit improvements

kdc/kerberos5.c

@@ -432,7 +432,7 @@ pa_enc_chal_validate(kdc_request_t r, const PA_DATA *pa)
 
     heim_assert(r->armor_crypto != NULL, "ENC-CHAL called for non FAST");
     
-    if (b->kdc_options.request_anonymous) {
+    if (_kdc_is_anon_request(b)) {
 	ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
 	kdc_log(r->context, r->config, 0, "ENC-CHALL doesn't support anon");
 	return ret;
@@ -555,7 +555,7 @@ pa_enc_ts_validate(kdc_request_t r, const PA_DATA *pa)
     Key *pa_key;
     char *str;
 	
-    if (r->req.req_body.kdc_options.request_anonymous) {
+    if (_kdc_is_anon_request(&r->req.req_body)) {
 	ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
 	_kdc_set_e_text(r, "ENC-TS doesn't support anon");
 	goto out;
@@ -717,9 +717,14 @@ static const struct kdc_patypes pat[] = {
 	KRB5_PADATA_PK_AS_REQ_WIN, "PK-INIT(win2k)", PA_ANNOUNCE,
 	pa_pkinit_validate
     },
+    {
+	KRB5_PADATA_PKINIT_KX, "Anonymous PK-INIT", PA_ANNOUNCE,
+	NULL
+    },
 #else
     { KRB5_PADATA_PK_AS_REQ, "PK-INIT(ietf)", 0, NULL },
     { KRB5_PADATA_PK_AS_REQ_WIN, "PK-INIT(win2k)", 0, NULL },
+    { KRB5_PADATA_PKINIT_KX, "Anonymous PK-INIT", 0, NULL },
 #endif
     { KRB5_PADATA_PA_PK_OCSP_RESPONSE , "OCSP", 0, NULL },
     { 
@@ -1656,12 +1661,12 @@ _kdc_as_rep(kdc_request_t r,
      */
 
     if (_kdc_is_anonymous(context, r->client_princ)) {
-	if (!b->kdc_options.request_anonymous) {
+	if (!_kdc_is_anon_request(b)) {
 	    kdc_log(context, config, 0, "Anonymous ticket w/o anonymous flag");
 	    ret = KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN;
 	    goto out;
 	}
-    } else if (b->kdc_options.request_anonymous) {
+    } else if (_kdc_is_anon_request(b)) {
 	kdc_log(context, config, 0,
 		"Request for a anonymous ticket with non "
 		"anonymous client name: %s", r->client_name);
@@ -1810,7 +1815,7 @@ _kdc_as_rep(kdc_request_t r,
 	 * send requre preauth is its required or anon is requested,
 	 * anon is today only allowed via preauth mechanisms.
 	 */
-	if (require_preauth_p(r) || b->kdc_options.request_anonymous) {
+	if (require_preauth_p(r) || _kdc_is_anon_request(b)) {
 	    ret = KRB5KDC_ERR_PREAUTH_REQUIRED;
 	    _kdc_set_e_text(r, "Need to use PA-ENC-TIMESTAMP/PA-PK-AS-REQ");
 	    goto out;
@@ -1854,7 +1859,7 @@ _kdc_as_rep(kdc_request_t r,
 	goto out;
 
     if(f.renew || f.validate || f.proxy || f.forwarded || f.enc_tkt_in_skey
-       || (f.request_anonymous && !config->allow_anonymous)) {
+       || (_kdc_is_anon_request(b) && !config->allow_anonymous)) {
 	ret = KRB5KDC_ERR_BADOPTION;
 	_kdc_set_e_text(r, "Bad KDC options");
 	goto out;
@@ -1867,7 +1872,11 @@ _kdc_as_rep(kdc_request_t r,
     rep.pvno = 5;
     rep.msg_type = krb_as_rep;
 
-    ret = copy_Realm(&r->client->entry.principal->realm, &rep.crealm);
+    if (_kdc_is_anonymous(context, r->client_princ)) {
+	Realm anon_realm=KRB5_ANON_REALM;
+	ret = copy_Realm(&anon_realm, &rep.crealm);
+    } else
+	ret = copy_Realm(&r->client->entry.principal->realm, &rep.crealm);
     if (ret)
 	goto out;
     ret = _krb5_principal2principalname(&rep.cname, r->client->entry.principal);
@@ -1973,7 +1982,7 @@ _kdc_as_rep(kdc_request_t r,
 	}
     }
 
-    if (f.request_anonymous)
+    if (_kdc_is_anon_request(b))
 	r->et.flags.anonymous = 1;
 
     if(b->addresses){
@@ -2320,3 +2329,14 @@ _kdc_tkt_add_if_relevant_ad(krb5_context context,
 
     return 0;
 }
+
+krb5_boolean
+_kdc_is_anon_request(const KDC_REQ_BODY *b)
+{
+	/* some versions of heimdal use bit 14 instead of 16 for
+	   request_anonymous, as indicated in the anonymous draft prior to
+	   version 11. Bit 14 is assigned to S4U2Proxy, but all S4U2Proxy
+	   requests will have a second ticket; don't consider those anonymous */
+	return (b->kdc_options.request_anonymous ||
+		(b->kdc_options.constrained_delegation && !b->additional_tickets));
+}

kdc/pkinit.c

@@ -573,7 +573,7 @@ _kdc_pk_rd_padata(krb5_context context,
 
 	type = "PK-INIT-Win2k";
 
-	if (req->req_body.kdc_options.request_anonymous) {
+	if (_kdc_is_anon_request(&req->req_body)) {
 	    ret = KRB5_KDC_ERR_PUBLIC_KEY_ENCRYPTION_NOT_SUPPORTED;
 	    krb5_set_error_message(context, ret,
 				   "Anon not supported in RSA mode");
@@ -719,7 +719,7 @@ _kdc_pk_rd_padata(krb5_context context,
 	hx509_certs signer_certs;
 	int flags = HX509_CMS_VS_ALLOW_DATA_OID_MISMATCH; /* BTMM */
 
-	if (req->req_body.kdc_options.request_anonymous)
+	if (_kdc_is_anon_request(&req->req_body))
 	    flags |= HX509_CMS_VS_ALLOW_ZERO_SIGNER;
 
 	ret = hx509_cms_verify_signed(context->hx509ctx,
@@ -804,7 +804,7 @@ _kdc_pk_rd_padata(krb5_context context,
 	    goto out;
 	}
 
-	if (req->req_body.kdc_options.request_anonymous &&
+	if (_kdc_is_anon_request(&req->req_body) &&
 	    ap.clientPublicValue == NULL) {
 	    free_AuthPack(&ap);
 	    ret = KRB5_KDC_ERR_PUBLIC_KEY_ENCRYPTION_NOT_SUPPORTED;
@@ -1370,16 +1370,86 @@ _kdc_pk_mk_pa_reply(krb5_context context,
 	    if (rep.u.encKeyPack.length != size)
 		krb5_abortx(context, "Internal ASN.1 encoder error");
 
-	    /* XXX KRB-FX-CF2 */
-	    ret = krb5_generate_random_keyblock(context, sessionetype,
-						sessionkey);
-	    if (ret) {
-		free_PA_PK_AS_REP(&rep);
-		goto out;
+	    /* generate the session key using the method from RFC6112 */
+	    {
+		krb5_keyblock kdc_contribution_key;
+		krb5_crypto reply_crypto;
+		krb5_crypto kdccont_crypto;
+		krb5_data p1 = { strlen("PKINIT"), "PKINIT"};
+		krb5_data p2 = { strlen("KEYEXCHANGE"), "KEYEXCHANGE"};
+		void *kckdata;
+		size_t kcklen;
+		EncryptedData kx;
+		void *kxdata;
+		size_t kxlen;
+
+		ret = krb5_generate_random_keyblock(context, sessionetype,
+						&kdc_contribution_key);
+		if (ret) {
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		ret = krb5_crypto_init(context, &cp->reply_key, enctype, &reply_crypto);
+		if (ret) {
+		    krb5_free_keyblock_contents(context, &kdc_contribution_key);
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		ret = krb5_crypto_init(context, &kdc_contribution_key, sessionetype, &kdccont_crypto);
+		if (ret) {
+		    krb5_crypto_destroy(context, reply_crypto);
+		    krb5_free_keyblock_contents(context, &kdc_contribution_key);
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		/* KRB-FX-CF2 */
+		ret = krb5_crypto_fx_cf2(context, kdccont_crypto, reply_crypto,
+					 &p1, &p2, sessionetype, sessionkey);
+		krb5_crypto_destroy(context, kdccont_crypto);
+		if (ret) {
+		    krb5_crypto_destroy(context, reply_crypto);
+		    krb5_free_keyblock_contents(context, &kdc_contribution_key);
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		ASN1_MALLOC_ENCODE(EncryptionKey, kckdata, kcklen,
+				   &kdc_contribution_key, &size, ret);
+		krb5_free_keyblock_contents(context, &kdc_contribution_key);
+		if (ret) {
+		    krb5_set_error_message(context, ret, "encoding of PKINIT-KX Key failed %d", ret);
+		    krb5_crypto_destroy(context, reply_crypto);
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		if (kcklen != size)
+		    krb5_abortx(context, "Internal ASN.1 encoder error");
+		ret = krb5_encrypt_EncryptedData(context, reply_crypto, KRB5_KU_PA_PKINIT_KX,
+					kckdata, kcklen, 0, &kx);
+		krb5_crypto_destroy(context, reply_crypto);
+		free(kckdata);
+		if (ret) {
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		ASN1_MALLOC_ENCODE(EncryptedData, kxdata, kxlen,
+				   &kx, &size, ret);
+		free_EncryptedData(&kx);
+		if (ret) {
+		    krb5_set_error_message(context, ret, "encoding of PKINIT-KX failed %d", ret);
+		    free_PA_PK_AS_REP(&rep);
+		    goto out;
+		}
+		if (kxlen != size)
+		    krb5_abortx(context, "Internal ASN.1 encoder error");
+		/* Add PA-PKINIT-KX */
+		ret = krb5_padata_add(context, md, KRB5_PADATA_PKINIT_KX, kxdata, kxlen);
+		if (ret) {
+		    krb5_set_error_message(context, ret,
+					   "Failed adding PKINIT-KX %d", ret);
+		    free(buf);
+		    goto out;
+		}
 	    }
-
-	    /* XXX Add PA-PKINIT-KX */
-
 	}
 
 #define use_btmm_with_enckey 0

lib/asn1/krb5.asn1

@@ -338,8 +338,8 @@ TicketFlags ::= BIT STRING {
 	hw-authent(11),
 	transited-policy-checked(12),
 	ok-as-delegate(13),
-	anonymous(14),
-	enc-pa-rep(15)
+	enc-pa-rep(15),
+	anonymous(16)
 }
 
 KDCOptions ::= BIT STRING {
@@ -351,9 +351,9 @@ KDCOptions ::= BIT STRING {
 	allow-postdate(5),
 	postdated(6),
 	renewable(8),
-	request-anonymous(14),
+	constrained-delegation(14), -- ms extension (aka cname-in-addl-tkt)
 	canonicalize(15),
-	constrained-delegation(16), -- ms extension
+	request-anonymous(16),
 	disable-transited-check(26),
 	renewable-ok(27),
 	enc-tkt-in-skey(28),