Merge branch 'ocsp-fixes'

Fixes a regression with handling OCSP error responses and adds a new
option to specify the length of nonces in OCSP requests.  Also adds some
other improvements for OCSP handling and fuzzers for OCSP
requests/responses.

Closes strongswan/strongswan#2011

conf/options/charon.opt

@@ -302,6 +302,13 @@ charon.nbns1
 charon.nbns2
 	WINS servers assigned to peer via configuration payload (CP).
 
+charon.ocsp_nonce_len = 32
+	Length of nonces in OCSP requests (1-32).
+
+	Length of nonces in OCSP requests. According to RFC 8954, valid values are
+	between 1 and 32, with new clients required to use 32. Some servers might
+	not support that so lowering the value to e.g. 16 might be necessary.
+
 charon.port = 500
 	UDP port used locally. If set to 0 a random port will be allocated.
 

fuzz/.gitignore

@@ -1,5 +1,7 @@
 fuzz_certs
 fuzz_crls
+fuzz_ocsp_req
+fuzz_ocsp_rsp
 fuzz_ids
 fuzz_pa_tnc
 fuzz_pb_tnc

fuzz/Makefile.am

@@ -25,7 +25,8 @@ pb_tnc_ldflags = \
 	$(top_builddir)/src/libtncif/.libs/libtncif.a \
 	$(fuzz_ldflags)
 
-FUZZ_TARGETS=fuzz_certs fuzz_crls fuzz_ids fuzz_pa_tnc fuzz_pb_tnc
+FUZZ_TARGETS=fuzz_certs fuzz_crls fuzz_ocsp_req fuzz_ocsp_rsp \
+	fuzz_ids fuzz_pa_tnc fuzz_pb_tnc
 
 all-local: $(FUZZ_TARGETS)
 
@@ -37,6 +38,12 @@ fuzz_certs: fuzz_certs.c ${libfuzzer}
 fuzz_crls: fuzz_crls.c ${libfuzzer}
 	$(CC) $(AM_CPPFLAGS) $(CFLAGS) -o $@ $< $(fuzz_ldflags)
 
+fuzz_ocsp_req: fuzz_ocsp_req.c ${libfuzzer}
+	$(CC) $(AM_CPPFLAGS) $(CFLAGS) -o $@ $< $(fuzz_ldflags)
+
+fuzz_ocsp_rsp: fuzz_ocsp_rsp.c ${libfuzzer}
+	$(CC) $(AM_CPPFLAGS) $(CFLAGS) -o $@ $< $(fuzz_ldflags)
+
 fuzz_ids: fuzz_ids.c ${libfuzzer}
 	$(CC) $(AM_CPPFLAGS) $(CFLAGS) -o $@ $< $(fuzz_ldflags)
 

fuzz/fuzz_ocsp_req.c

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2023 Tobias Brunner
+ *
+ * Copyright (C) secunet Security Networks AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include <library.h>
+#include <utils/debug.h>
+
+int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len)
+{
+	certificate_t *cert;
+	chunk_t chunk;
+
+	dbg_default_set_level(-1);
+	library_init(NULL, "fuzz_ocsp_req");
+	plugin_loader_add_plugindirs(PLUGINDIR, PLUGINS);
+	if (!lib->plugins->load(lib->plugins, PLUGINS))
+	{
+		return 1;
+	}
+
+	chunk = chunk_create((u_char*)buf, len);
+	cert = lib->creds->create(lib->creds, CRED_CERTIFICATE, CERT_X509_OCSP_REQUEST,
+							  BUILD_BLOB, chunk, BUILD_END);
+	DESTROY_IF(cert);
+
+	lib->plugins->unload(lib->plugins);
+	library_deinit();
+	return 0;
+}

fuzz/fuzz_ocsp_rsp.c

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2023 Tobias Brunner
+ *
+ * Copyright (C) secunet Security Networks AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include <library.h>
+#include <utils/debug.h>
+
+int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len)
+{
+	certificate_t *cert;
+	chunk_t chunk;
+
+	dbg_default_set_level(-1);
+	library_init(NULL, "fuzz_ocsp_rsp");
+	plugin_loader_add_plugindirs(PLUGINDIR, PLUGINS);
+	if (!lib->plugins->load(lib->plugins, PLUGINS))
+	{
+		return 1;
+	}
+
+	chunk = chunk_create((u_char*)buf, len);
+	cert = lib->creds->create(lib->creds, CRED_CERTIFICATE, CERT_X509_OCSP_RESPONSE,
+							  BUILD_BLOB, chunk, BUILD_END);
+	DESTROY_IF(cert);
+
+	lib->plugins->unload(lib->plugins);
+	library_deinit();
+	return 0;
+}

src/libstrongswan/credentials/certificates/certificate_printer.c

@@ -558,6 +558,11 @@ static void print_ocsp_response(private_certificate_printer_t *this,
 			fprintf(f, "\n");
 		}
 		enumerator->destroy(enumerator);
+
+		if (first)
+		{
+			fprintf(f, "(none)\n");
+		}
 	}
 }
 

src/libstrongswan/credentials/certificates/ocsp_response.h

@@ -56,6 +56,13 @@ struct ocsp_response_t {
 	 */
 	certificate_t certificate;
 
+	/**
+	 * Get general status of this OCSP response.
+	 *
+	 * @return					OCSP status
+	 */
+	ocsp_status_t (*get_ocsp_status)(ocsp_response_t *this);
+
 	/**
 	 * Get the nonce received with this OCSP response.
 	 *

src/libstrongswan/plugins/revocation/revocation_validator.c

@@ -121,8 +121,14 @@ static certificate_t *fetch_ocsp(char *url, certificate_t *subject,
 		request->destroy(request);
 		return NULL;
 	}
-	ocsp_request = (ocsp_request_t*)request;
 	ocsp_response = (ocsp_response_t*)response;
+	if (ocsp_response->get_ocsp_status(ocsp_response) != OCSP_SUCCESSFUL)
+	{
+		response->destroy(response);
+		request->destroy(request);
+		return NULL;
+	}
+	ocsp_request = (ocsp_request_t*)request;
 	if (ocsp_response->get_nonce(ocsp_response).len &&
 		!chunk_equals_const(ocsp_request->get_nonce(ocsp_request),
 							ocsp_response->get_nonce(ocsp_response)))

src/libstrongswan/plugins/x509/x509_ocsp_request.c

@@ -205,9 +205,13 @@ static chunk_t build_requestList(private_x509_ocsp_request_t *this)
 static chunk_t build_nonce(private_x509_ocsp_request_t *this)
 {
 	rng_t *rng;
+	int nonce_len;
+
+	nonce_len = lib->settings->get_int(lib->settings, "%s.ocsp_nonce_len",
+									   NONCE_LEN, lib->ns);
 
 	rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK);
-	if (!rng || !rng->allocate_bytes(rng, NONCE_LEN, &this->nonce))
+	if (!rng || !rng->allocate_bytes(rng, max(1, nonce_len), &this->nonce))
 	{
 		DBG1(DBG_LIB, "failed to create RNG");
 		DESTROY_IF(rng);

src/libstrongswan/plugins/x509/x509_ocsp_response.c

@@ -263,6 +263,12 @@ METHOD(ocsp_response_t, create_response_enumerator, enumerator_t*,
 				filter, NULL, NULL);
 }
 
+METHOD(ocsp_response_t, get_ocsp_status, ocsp_status_t,
+	private_x509_ocsp_response_t *this)
+{
+	return this->ocsp_status;
+}
+
 METHOD(ocsp_response_t, get_nonce, chunk_t,
 	private_x509_ocsp_response_t *this)
 {
@@ -612,49 +618,49 @@ static bool build_basicOCSPResponse(private_x509_ocsp_response_t *this,
  * ASN.1 definition of basicResponse
  */
 static const asn1Object_t basicResponseObjects[] = {
-	{ 0, "BasicOCSPResponse",				ASN1_SEQUENCE,			ASN1_NONE }, /*  0 */
+	{ 0, "BasicOCSPResponse",				ASN1_SEQUENCE,			ASN1_NONE            }, /*  0 */
-	{ 1,   "tbsResponseData",				ASN1_SEQUENCE,			ASN1_OBJ  }, /*  1 */
+	{ 1,   "tbsResponseData",				ASN1_SEQUENCE,			ASN1_OBJ             }, /*  1 */
-	{ 2,     "versionContext",				ASN1_CONTEXT_C_0,		ASN1_NONE |
+	{ 2,     "versionContext",				ASN1_CONTEXT_C_0,		ASN1_NONE|ASN1_DEF   }, /*  2 */
-																	ASN1_DEF  }, /*  2 */
+	{ 3,       "version",					ASN1_INTEGER,			ASN1_BODY            }, /*  3 */
-	{ 3,       "version",					ASN1_INTEGER,			ASN1_BODY }, /*  3 */
+	{ 2,     "responderId",					ASN1_EOC,				ASN1_CHOICE          }, /*  4 */
-	{ 2,     "responderIdContext",			ASN1_CONTEXT_C_1,		ASN1_OPT  }, /*  4 */
+	{ 3,       "responderIdContext",		ASN1_CONTEXT_C_1,		ASN1_OPT             }, /*  5 */
-	{ 3,       "responderIdByName",			ASN1_SEQUENCE,			ASN1_OBJ  }, /*  5 */
+	{ 4,         "responderIdByName",		ASN1_SEQUENCE,			ASN1_OBJ             }, /*  6 */
-	{ 2,     "end choice",					ASN1_EOC,				ASN1_END  }, /*  6 */
+	{ 3,       "end choice",				ASN1_EOC,				ASN1_END|ASN1_CH     }, /*  7 */
-	{ 2,     "responderIdContext",			ASN1_CONTEXT_C_2,		ASN1_OPT  }, /*  7 */
+	{ 3,       "responderIdContext",		ASN1_CONTEXT_C_2,		ASN1_OPT             }, /*  8 */
-	{ 3,       "responderIdByKey",			ASN1_OCTET_STRING,		ASN1_BODY }, /*  8 */
+	{ 4,         "responderIdByKey",		ASN1_OCTET_STRING,		ASN1_BODY            }, /*  9 */
-	{ 2,     "end choice",					ASN1_EOC,				ASN1_END  }, /*  9 */
+	{ 3,       "end choice",				ASN1_EOC,				ASN1_END|ASN1_CH     }, /* 10 */
-	{ 2,     "producedAt",					ASN1_GENERALIZEDTIME,	ASN1_BODY }, /* 10 */
+	{ 2,     "end choices",					ASN1_EOC,				ASN1_END|ASN1_CHOICE }, /* 11 */
-	{ 2,     "responses",					ASN1_SEQUENCE,			ASN1_OBJ  }, /* 11 */
+	{ 2,     "producedAt",					ASN1_GENERALIZEDTIME,	ASN1_BODY            }, /* 12 */
-	{ 2,     "responseExtensionsContext",	ASN1_CONTEXT_C_1,		ASN1_OPT  }, /* 12 */
+	{ 2,     "responses",					ASN1_SEQUENCE,			ASN1_OBJ             }, /* 13 */
-	{ 3,       "responseExtensions",		ASN1_SEQUENCE,			ASN1_LOOP }, /* 13 */
+	{ 2,     "responseExtensionsContext",	ASN1_CONTEXT_C_1,		ASN1_OPT             }, /* 14 */
-	{ 4,         "extension",				ASN1_SEQUENCE,			ASN1_NONE }, /* 14 */
+	{ 3,       "responseExtensions",		ASN1_SEQUENCE,			ASN1_LOOP            }, /* 15 */
-	{ 5,           "extnID",				ASN1_OID,				ASN1_BODY }, /* 15 */
+	{ 4,         "extension",				ASN1_SEQUENCE,			ASN1_NONE            }, /* 16 */
-	{ 5,           "critical",				ASN1_BOOLEAN,			ASN1_BODY |
+	{ 5,           "extnID",				ASN1_OID,				ASN1_BODY            }, /* 17 */
-																	ASN1_DEF  }, /* 16 */
+	{ 5,           "critical",				ASN1_BOOLEAN,			ASN1_BODY | ASN1_DEF }, /* 18 */
-	{ 5,           "extnValue",				ASN1_OCTET_STRING,		ASN1_BODY }, /* 17 */
+	{ 5,           "extnValue",				ASN1_OCTET_STRING,		ASN1_BODY            }, /* 19 */
-	{ 3,       "end loop",					ASN1_EOC,				ASN1_END  }, /* 18 */
+	{ 3,       "end loop",					ASN1_EOC,				ASN1_END             }, /* 20 */
-	{ 2,     "end opt",						ASN1_EOC,				ASN1_END  }, /* 19 */
+	{ 2,     "end opt",						ASN1_EOC,				ASN1_END             }, /* 21 */
-	{ 1,   "signatureAlgorithm",			ASN1_EOC,				ASN1_RAW  }, /* 20 */
+	{ 1,   "signatureAlgorithm",			ASN1_EOC,				ASN1_RAW             }, /* 22 */
-	{ 1,   "signature",						ASN1_BIT_STRING,		ASN1_BODY }, /* 21 */
+	{ 1,   "signature",						ASN1_BIT_STRING,		ASN1_BODY            }, /* 23 */
-	{ 1,   "certsContext",					ASN1_CONTEXT_C_0,		ASN1_OPT  }, /* 22 */
+	{ 1,   "certsContext",					ASN1_CONTEXT_C_0,		ASN1_OPT             }, /* 24 */
-	{ 2,     "certs",						ASN1_SEQUENCE,			ASN1_LOOP }, /* 23 */
+	{ 2,     "certs",						ASN1_SEQUENCE,			ASN1_LOOP            }, /* 25 */
-	{ 3,       "certificate",				ASN1_SEQUENCE,			ASN1_RAW  }, /* 24 */
+	{ 3,       "certificate",				ASN1_SEQUENCE,			ASN1_RAW             }, /* 26 */
-	{ 2,     "end loop",					ASN1_EOC,				ASN1_END  }, /* 25 */
+	{ 2,     "end loop",					ASN1_EOC,				ASN1_END             }, /* 27 */
-	{ 1,   "end opt",						ASN1_EOC,				ASN1_END  }, /* 26 */
+	{ 1,   "end opt",						ASN1_EOC,				ASN1_END             }, /* 28 */
-	{ 0, "exit",							ASN1_EOC,				ASN1_EXIT }
+	{ 0, "exit",							ASN1_EOC,				ASN1_EXIT            }
 };
 #define BASIC_RESPONSE_TBS_DATA		 1
 #define BASIC_RESPONSE_VERSION		 3
-#define BASIC_RESPONSE_ID_BY_NAME	 5
+#define BASIC_RESPONSE_ID_BY_NAME	 6
-#define BASIC_RESPONSE_ID_BY_KEY	 8
+#define BASIC_RESPONSE_ID_BY_KEY	 9
-#define BASIC_RESPONSE_PRODUCED_AT	10
+#define BASIC_RESPONSE_PRODUCED_AT	12
-#define BASIC_RESPONSE_RESPONSES	11
+#define BASIC_RESPONSE_RESPONSES	13
-#define BASIC_RESPONSE_EXT_ID		15
+#define BASIC_RESPONSE_EXT_ID		17
-#define BASIC_RESPONSE_CRITICAL		16
+#define BASIC_RESPONSE_CRITICAL		18
-#define BASIC_RESPONSE_EXT_VALUE	17
+#define BASIC_RESPONSE_EXT_VALUE	19
-#define BASIC_RESPONSE_ALGORITHM	20
+#define BASIC_RESPONSE_ALGORITHM	22
-#define BASIC_RESPONSE_SIGNATURE	21
+#define BASIC_RESPONSE_SIGNATURE	23
-#define BASIC_RESPONSE_CERTIFICATE	24
+#define BASIC_RESPONSE_CERTIFICATE	26
 
 /**
  * Parse a basicOCSPResponse
@@ -756,11 +762,6 @@ end:
 	parser->destroy(parser);
 	if (success)
 	{
-		if (!this->responderId)
-		{
-			this->responderId = identification_create_from_encoding(ID_ANY,
-									chunk_empty);
-		}
 		success = parse_responses(this, responses, responses_level);
 	}
 	return success;
@@ -826,6 +827,10 @@ static bool parse_OCSPResponse(private_x509_ocsp_response_t *this)
 		switch (objectID)
 		{
 			case OCSP_RESPONSE_STATUS:
+				if (object.len != 1)
+				{
+					goto end;
+				}
 				this->ocsp_status = (ocsp_status_t)*object.ptr;
 				switch (this->ocsp_status)
 				{
@@ -878,7 +883,11 @@ METHOD(certificate_t, get_issuer, identification_t*,
 METHOD(certificate_t, has_issuer, id_match_t,
 	private_x509_ocsp_response_t *this, identification_t *issuer)
 {
-	return this->responderId->matches(this->responderId, issuer);
+	if (this->responderId)
+	{
+		return this->responderId->matches(this->responderId, issuer);
+	}
+	return ID_MATCH_NONE;
 }
 
 METHOD(certificate_t, issued_by, bool,
@@ -889,7 +898,7 @@ METHOD(certificate_t, issued_by, bool,
 	bool valid;
 	x509_t *x509 = (x509_t*)issuer;
 
-	if (issuer->get_type(issuer) != CERT_X509)
+	if (issuer->get_type(issuer) != CERT_X509 || !this->responderId)
 	{
 		return FALSE;
 	}
@@ -1050,6 +1059,7 @@ static private_x509_ocsp_response_t *create_empty()
 					.get_ref = _get_ref,
 					.destroy = _destroy,
 				},
+				.get_ocsp_status = _get_ocsp_status,
 				.get_nonce = _get_nonce,
 				.get_status = _get_status,
 				.create_cert_enumerator = _create_cert_enumerator,

src/pki/commands/ocsp.c

@@ -528,6 +528,11 @@ gen:
 				ocsp_status = OCSP_INTERNALERROR;
 			}
 		}
+		else
+		{
+			DBG1(DBG_APP, "no signer certificate found");
+			ocsp_status = OCSP_INTERNALERROR;
+		}
 		DBG1(DBG_APP, "ocspResponseStatus:  %N", ocsp_status_names, ocsp_status);
 
 		enumerator = responses->create_enumerator(responses);