From 5808467ed107d7bda8c37cc63f77465a2c30acd3 Mon Sep 17 00:00:00 2001 From: Tobias Brunner Date: Mon, 5 Mar 2018 09:45:34 +0100 Subject: [PATCH] pkcs5: Parse PRF algorithms if given in PBKDF2-params as defined in RFC 8018 We can't use ASN1_DEF, which would technically be more correct, as the ASN.1 parser currently can't handle that. For algorithm identifiers we often use ASN1_EOC as type (with ASN1_RAW), however, that doesn't work with ASN1_DEF because the element is assumed missing if the type doesn't match. On the other hand, we can't set the type to ASN1_SEQUENCE because then the parser skips the following rule if the element is missing (it does so for all constructed types, but I guess is mainly intended for context tags), which in this case overruns the parser rules array. --- src/libstrongswan/crypto/pkcs5.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) diff --git a/src/libstrongswan/crypto/pkcs5.c b/src/libstrongswan/crypto/pkcs5.c index 8a1452425..96f0aae53 100644 --- a/src/libstrongswan/crypto/pkcs5.c +++ b/src/libstrongswan/crypto/pkcs5.c @@ -422,7 +422,9 @@ static bool parse_pbes1_params(private_pkcs5_t *this, chunk_t blob, int level0) /** * ASN.1 definition of a PBKDF2-params structure * The salt is actually a CHOICE and could be an AlgorithmIdentifier from - * PBKDF2-SaltSources (but as per RFC 2898 that's for future versions). + * PBKDF2-SaltSources (but as per RFC 8018 that's for future versions). + * The PRF algorithm is actually defined as DEFAULT and not OPTIONAL, but the + * parser can't handle ASN1_DEF with SEQUENCEs. */ static const asn1Object_t pbkdf2ParamsObjects[] = { { 0, "PBKDF2-params", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */ @@ -430,7 +432,8 @@ static const asn1Object_t pbkdf2ParamsObjects[] = { { 1, "iterationCount",ASN1_INTEGER, ASN1_BODY }, /* 2 */ { 1, "keyLength", ASN1_INTEGER, ASN1_OPT|ASN1_BODY }, /* 3 */ { 1, "end opt", ASN1_EOC, ASN1_END }, /* 4 */ - { 1, "prf", ASN1_EOC, ASN1_DEF|ASN1_RAW }, /* 5 */ + { 1, "prf", ASN1_SEQUENCE, ASN1_OPT|ASN1_RAW }, /* 5 */ + { 1, "end opt", ASN1_EOC, ASN1_END }, /* 6 */ { 0, "exit", ASN1_EOC, ASN1_EXIT } }; #define PBKDF2_SALT 1 @@ -446,13 +449,15 @@ static bool parse_pbkdf2_params(private_pkcs5_t *this, chunk_t blob, int level0) asn1_parser_t *parser; chunk_t object; int objectID; - bool success; + bool success = FALSE; parser = asn1_parser_create(pbkdf2ParamsObjects, blob); parser->set_top_level(parser, level0); /* keylen is optional */ this->keylen = 0; + /* defaults to id-hmacWithSHA1 */ + this->data.pbes2.prf_alg = PRF_HMAC_SHA1; while (parser->iterate(parser, &objectID, &object)) { @@ -474,13 +479,22 @@ static bool parse_pbkdf2_params(private_pkcs5_t *this, chunk_t blob, int level0) break; } case PBKDF2_PRF: - { /* defaults to id-hmacWithSHA1, no other is currently defined */ - this->data.pbes2.prf_alg = PRF_HMAC_SHA1; + { + int oid; + + oid = asn1_parse_algorithmIdentifier(object, + parser->get_level(parser) + 1, NULL); + this->data.pbes2.prf_alg = pseudo_random_function_from_oid(oid); + if (this->data.pbes2.prf_alg == PRF_UNDEFINED) + { /* unsupported PRF algorithm */ + goto end; + } break; } } } success = parser->success(parser); +end: parser->destroy(parser); return success; }