From 076f1437fe82de0b1f0ecf9a7ca031cd94c0c579 Mon Sep 17 00:00:00 2001 From: Lev Stipakov Date: Fri, 23 Feb 2018 17:12:49 +0200 Subject: [PATCH] Enable allowing unsupported critical extensions in runtime When compile time flag MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION is not set, certificate parsing fails if certificate contains unsupported critical extension. This patch allows to modify this behavior in runtime. Signed-off-by: Lev Stipakov --- include/mbedtls/oid.h | 13 +++- include/mbedtls/ssl.h | 22 ++++++ include/mbedtls/x509_crt.h | 2 + library/oid.c | 81 ++++++++++++++++++---- library/ssl_tls.c | 8 +++ library/x509_crt.c | 10 ++- tests/data_files/test-ca-nc.crt | 20 ++++++ tests/suites/test_suite_x509parse.data | 6 ++ tests/suites/test_suite_x509parse.function | 15 ++++ 9 files changed, 162 insertions(+), 15 deletions(-) create mode 100644 tests/data_files/test-ca-nc.crt diff --git a/include/mbedtls/oid.h b/include/mbedtls/oid.h index 408645ece..b116736f8 100644 --- a/include/mbedtls/oid.h +++ b/include/mbedtls/oid.h @@ -410,7 +410,7 @@ int mbedtls_oid_get_numeric_string( char *buf, size_t size, const mbedtls_asn1_b #if defined(MBEDTLS_X509_USE_C) || defined(MBEDTLS_X509_CREATE_C) /** - * \brief Translate an X.509 extension OID into local values + * \brief Translate supported X.509 extension OID into local values * * \param oid OID to use * \param ext_type place to store the extension type @@ -418,6 +418,17 @@ int mbedtls_oid_get_numeric_string( char *buf, size_t size, const mbedtls_asn1_b * \return 0 if successful, or MBEDTLS_ERR_OID_NOT_FOUND */ int mbedtls_oid_get_x509_ext_type( const mbedtls_asn1_buf *oid, int *ext_type ); + +/** + * \brief Translate supported and unsupported X.509 extension OID into local values + * + * \param oid OID to use + * \param ext_type place to store the extension type + * \param is_supported place to store flag if extension is supported (1 - supported, 0 otherwise) + * + * \return 0 if successful, or MBEDTLS_ERR_OID_NOT_FOUND + */ +int mbedtls_oid_get_x509_ext_type_supported( const mbedtls_asn1_buf *oid, int *ext_type, int *is_supported ); #endif /** diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h index 5fd6969da..1087ea166 100644 --- a/include/mbedtls/ssl.h +++ b/include/mbedtls/ssl.h @@ -696,6 +696,10 @@ struct mbedtls_ssl_config retransmission timeout (ms) */ #endif + uint32_t allowed_unsupported_critical_exts; /*!< Bit flags which represent runtime-enabled + unsupported critical extensions, e.g. + MBEDTLS_X509_EXT_NAME_CONSTRAINTS */ + #if defined(MBEDTLS_SSL_RENEGOTIATION) int renego_max_records; /*!< grace period for renegotiation */ unsigned char renego_period[8]; /*!< value of the record counters @@ -2298,6 +2302,24 @@ void mbedtls_ssl_conf_renegotiation_period( mbedtls_ssl_config *conf, const unsigned char period[8] ); #endif /* MBEDTLS_SSL_RENEGOTIATION */ +/** + * \brief Allows unsupported critical extensions + * + * Without compile-time flag MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION + * mbedTLS fails certificate verification if certificate contains + * unsupported critical extensions. + * + * This method allows to modify behavior in runtime by providing + * bit flags which represent unsupported extensions (for example MBEDTLS_X509_EXT_NAME_CONSTRAINTS) + * which should be allowed despite missing above mentioned compile-time flag. + * + * \param conf SSL configuration + * \param exts Bit flags which represent runtime-enabled unsupported critical extensions, + * e.g. MBEDTLS_X509_EXT_NAME_CONSTRAINTS + * + */ +void mbedtls_ssl_conf_allow_unsupported_critical_exts( mbedtls_ssl_config *conf, uint32_t exts ); + /** * \brief Return the number of data bytes available to read * diff --git a/include/mbedtls/x509_crt.h b/include/mbedtls/x509_crt.h index e72231ee8..9df19e52c 100644 --- a/include/mbedtls/x509_crt.h +++ b/include/mbedtls/x509_crt.h @@ -90,6 +90,8 @@ typedef struct mbedtls_x509_crt mbedtls_pk_type_t sig_pk; /**< Internal representation of the Public Key algorithm of the signature algorithm, e.g. MBEDTLS_PK_RSA */ void *sig_opts; /**< Signature options to be passed to mbedtls_pk_verify_ext(), e.g. for RSASSA-PSS */ + uint32_t allowed_unsupported_critical_exts; /**< Optional Bit flags which represent runtime-enabled unsupported critical extensions, e.g. MBEDTLS_X509_EXT_NAME_CONSTRAINTS */ + struct mbedtls_x509_crt *next; /**< Next certificate in the CA-chain. */ } mbedtls_x509_crt; diff --git a/library/oid.c b/library/oid.c index edea950f8..a756d2801 100644 --- a/library/oid.c +++ b/library/oid.c @@ -254,38 +254,95 @@ FN_OID_GET_ATTR1(mbedtls_oid_get_attr_short_name, oid_x520_attr_t, x520_attr, co typedef struct { mbedtls_oid_descriptor_t descriptor; int ext_type; + int is_supported; } oid_x509_ext_t; static const oid_x509_ext_t oid_x509_ext[] = { { - { ADD_LEN( MBEDTLS_OID_BASIC_CONSTRAINTS ), "id-ce-basicConstraints", "Basic Constraints" }, - MBEDTLS_X509_EXT_BASIC_CONSTRAINTS, + { ADD_LEN( MBEDTLS_OID_AUTHORITY_KEY_IDENTIFIER ), "id-ce-authorityKeyIdentifier", "Authority Key Identifier" }, + MBEDTLS_X509_EXT_AUTHORITY_KEY_IDENTIFIER, 0, }, { - { ADD_LEN( MBEDTLS_OID_KEY_USAGE ), "id-ce-keyUsage", "Key Usage" }, - MBEDTLS_X509_EXT_KEY_USAGE, + { ADD_LEN( MBEDTLS_OID_SUBJECT_KEY_IDENTIFIER ), "id-ce-subjectKeyIdentifier", "Subject Key Identifier" }, + MBEDTLS_X509_EXT_SUBJECT_KEY_IDENTIFIER, 0, }, { - { ADD_LEN( MBEDTLS_OID_EXTENDED_KEY_USAGE ), "id-ce-extKeyUsage", "Extended Key Usage" }, - MBEDTLS_X509_EXT_EXTENDED_KEY_USAGE, + { ADD_LEN( MBEDTLS_OID_KEY_USAGE ), "id-ce-keyUsage", "Key Usage" }, + MBEDTLS_X509_EXT_KEY_USAGE, 1, }, { - { ADD_LEN( MBEDTLS_OID_SUBJECT_ALT_NAME ), "id-ce-subjectAltName", "Subject Alt Name" }, - MBEDTLS_X509_EXT_SUBJECT_ALT_NAME, + { ADD_LEN( MBEDTLS_OID_CERTIFICATE_POLICIES ), "id-ce-certificatePolicies", "Certificate Policies" }, + MBEDTLS_X509_EXT_CERTIFICATE_POLICIES, 0, }, { - { ADD_LEN( MBEDTLS_OID_NS_CERT_TYPE ), "id-netscape-certtype", "Netscape Certificate Type" }, - MBEDTLS_X509_EXT_NS_CERT_TYPE, + { ADD_LEN( MBEDTLS_OID_POLICY_MAPPINGS ), "id-ce-policyMappings", "Policy Mapping" }, + MBEDTLS_X509_EXT_POLICY_MAPPINGS, 0, + }, + { + { ADD_LEN( MBEDTLS_OID_ISSUER_ALT_NAME ), "id-ce-issuerAltName", "Issuer Alt Name" }, + MBEDTLS_X509_EXT_ISSUER_ALT_NAME, 0, + }, + { + { ADD_LEN( MBEDTLS_OID_SUBJECT_DIRECTORY_ATTRS ), "id-ce-subjectDirectoryAttributes", "Subject Directory Attributes" }, + MBEDTLS_X509_EXT_SUBJECT_DIRECTORY_ATTRS, 0, + }, + { + { ADD_LEN( MBEDTLS_OID_BASIC_CONSTRAINTS ), "id-ce-basicConstraints", "Basic Constraints" }, + MBEDTLS_X509_EXT_BASIC_CONSTRAINTS, 1, + }, + { + { ADD_LEN( MBEDTLS_OID_NAME_CONSTRAINTS ), "id-ce-nameConstraints", "Name Constraints" }, + MBEDTLS_X509_EXT_NAME_CONSTRAINTS, 0, + }, + { + { ADD_LEN( MBEDTLS_OID_POLICY_CONSTRAINTS ), "id-ce-policyConstraints", "Policy Constraints" }, + MBEDTLS_X509_EXT_POLICY_CONSTRAINTS, 0, + }, + { + { ADD_LEN( MBEDTLS_OID_EXTENDED_KEY_USAGE ), "id-ce-extKeyUsage", "Extended Key Usage" }, + MBEDTLS_X509_EXT_EXTENDED_KEY_USAGE, 1 + }, + { + { ADD_LEN( MBEDTLS_OID_CRL_DISTRIBUTION_POINTS ), "id-ce-cRLDistributionPoints", "CRL Distribution Points" }, + MBEDTLS_X509_EXT_CRL_DISTRIBUTION_POINTS, 0, + }, + { + { ADD_LEN( MBEDTLS_OID_INIHIBIT_ANYPOLICY ), "id-ce-inhibitAnyPolicy", "Inhibit Any Policy" }, + MBEDTLS_X509_EXT_INIHIBIT_ANYPOLICY, 0, + }, + { + { ADD_LEN( MBEDTLS_OID_FRESHEST_CRL ), "id-ce-freshestCRL", "Freshest CRL" }, + MBEDTLS_X509_EXT_FRESHEST_CRL, 0, + }, + { + { ADD_LEN( MBEDTLS_OID_SUBJECT_ALT_NAME ), "id-ce-subjectAltName", "Subject Alt Name" }, + MBEDTLS_X509_EXT_SUBJECT_ALT_NAME, 1 + }, + { + { ADD_LEN( MBEDTLS_OID_NS_CERT_TYPE ), "id-netscape-certtype", "Netscape Certificate Type" }, + MBEDTLS_X509_EXT_NS_CERT_TYPE, 1 }, { { NULL, 0, NULL, NULL }, - 0, + 0, 0 }, }; FN_OID_TYPED_FROM_ASN1(oid_x509_ext_t, x509_ext, oid_x509_ext) -FN_OID_GET_ATTR1(mbedtls_oid_get_x509_ext_type, oid_x509_ext_t, x509_ext, int, ext_type) +FN_OID_GET_ATTR2(mbedtls_oid_get_x509_ext_type_supported, oid_x509_ext_t, x509_ext, int, ext_type, int, is_supported) + +int mbedtls_oid_get_x509_ext_type( const mbedtls_asn1_buf *oid, int *ext_type ) +{ + int ret = 0; + int is_supported = 0; + + ret = mbedtls_oid_get_x509_ext_type_supported(oid, ext_type, &is_supported); + if( is_supported == 0 ) + ret = MBEDTLS_ERR_OID_NOT_FOUND; + + return( ret ); +} static const mbedtls_oid_descriptor_t oid_ext_key_usage[] = { diff --git a/library/ssl_tls.c b/library/ssl_tls.c index 1270ee9b8..2ce3f9b7d 100644 --- a/library/ssl_tls.c +++ b/library/ssl_tls.c @@ -4668,6 +4668,9 @@ int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl ) mbedtls_x509_crt_init( ssl->session_negotiate->peer_cert ); + ssl->session_negotiate->peer_cert->allowed_unsupported_critical_exts = + ssl->conf->allowed_unsupported_critical_exts; + i += 3; while( i < ssl->in_hslen ) @@ -6626,6 +6629,11 @@ void mbedtls_ssl_conf_renegotiation_period( mbedtls_ssl_config *conf, } #endif /* MBEDTLS_SSL_RENEGOTIATION */ +void mbedtls_ssl_conf_allow_unsupported_critical_exts( mbedtls_ssl_config *conf, uint32_t exts ) +{ + conf->allowed_unsupported_critical_exts = exts; +} + #if defined(MBEDTLS_SSL_SESSION_TICKETS) #if defined(MBEDTLS_SSL_CLI_C) void mbedtls_ssl_conf_session_tickets( mbedtls_ssl_config *conf, int use_tickets ) diff --git a/library/x509_crt.c b/library/x509_crt.c index 3ad53a715..130b3ad1b 100644 --- a/library/x509_crt.c +++ b/library/x509_crt.c @@ -539,6 +539,7 @@ static int x509_get_crt_ext( unsigned char **p, int ret; size_t len; unsigned char *end_ext_data, *end_ext_octet; + int is_supported; if( *p == end ) return( 0 ); @@ -593,9 +594,9 @@ static int x509_get_crt_ext( unsigned char **p, /* * Detect supported extensions */ - ret = mbedtls_oid_get_x509_ext_type( &extn_oid, &ext_type ); + ret = mbedtls_oid_get_x509_ext_type_supported( &extn_oid, &ext_type, &is_supported ); - if( ret != 0 ) + if( ( ret != 0 ) || ( is_supported == 0 ) ) { /* No parser found, skip extension */ *p = end_ext_octet; @@ -603,6 +604,10 @@ static int x509_get_crt_ext( unsigned char **p, #if !defined(MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION) if( is_critical ) { + /* Do not fail if extension is found, but unsupported and allowed in runtime */ + if( ( ret == 0 ) && ( ext_type & crt->allowed_unsupported_critical_exts ) ) + continue; + /* Data is marked as critical: fail */ return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ); @@ -956,6 +961,7 @@ int mbedtls_x509_crt_parse_der( mbedtls_x509_crt *chain, const unsigned char *bu prev = crt; mbedtls_x509_crt_init( crt->next ); + crt->next->allowed_unsupported_critical_exts = crt->allowed_unsupported_critical_exts; crt = crt->next; } diff --git a/tests/data_files/test-ca-nc.crt b/tests/data_files/test-ca-nc.crt new file mode 100644 index 000000000..7e0c56134 --- /dev/null +++ b/tests/data_files/test-ca-nc.crt @@ -0,0 +1,20 @@ +-----BEGIN CERTIFICATE----- +MIIDSzCCAjOgAwIBAgIJAJx/NjT4C4viMA0GCSqGSIb3DQEBCwUAMBMxETAPBgNV +BAMMCExlZXZpQ0E0MB4XDTE4MDEyNzE1MDczMloXDTI4MDEyNTE1MDczMlowEzER +MA8GA1UEAwwITGVldmlDQTQwggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIB +AQDWN79RTlyFm5o0LVMSVjc68W0+gtl95xpaaD7IS6gDYjcbGnCwSefiq7y9rtck +OM1A5Bzhj5+iWbmZStUmeJUhSGgxP/FxuUaAV0fsBGJ5jDrzmbhzDkHsNxDMB2ks +XFyy4LfODcBs9TXxY43KUKuq/0meiT3WAaZWHMYle9vkQJM2l0RyH4IXHCHiIRwd +2wntin6T9QOFJOc2ietNb7KsXVne81wb7h9BVMsjCIAsbPpHa+PZQs1xFuxmRxCs +kpavnMy+SqevHhvqtvbHppcXYtZspTnkVoXWUdx3HHXgZMQKlAWlwyx57xpZBU2g +qksO+KCLVYOQMN9usmuMOpHHAgMBAAGjgaEwgZ4wHQYDVR0eAQH/BBMwEaAPMA2C +C2V4YW1wbGUuY29tMB0GA1UdDgQWBBR3T9IilPeRAFfLO8ocg216OBo+6DBDBgNV +HSMEPDA6gBR3T9IilPeRAFfLO8ocg216OBo+6KEXpBUwEzERMA8GA1UEAwwITGVl +dmlDQTSCCQCcfzY0+AuL4jAMBgNVHRMEBTADAQH/MAsGA1UdDwQEAwIBBjANBgkq +hkiG9w0BAQsFAAOCAQEAR086ciNM3ujSQNhhguqFHYGfDRRuAgOk4l7GXIfFa9te +B2KMLSwP367QaMwFxRrOoDvixIjzbpiiKB3cv+IXqGyfsRJw47XLwGK4FtSsXjst +m2M8W5iXBQ94XoLj9OKb4ZJWKI930S/PF7uuxICtWttYSoylfyMkiR45+1SLj2eF +X4EnXK3Q0H42v8LCDFqj9iNQ2WMLwA7kFPB+oOZxkFi2G0F3VuW+JZeBPQCpYdRO +0kQQ/gIZE6KEdscKHi9y6OfGSeRlDBMADky9NiZy7I3AcspLcmMQh/191/DnooNe +OwQ6w1HweApjB46bGyILpGUi9MZhvCnoLWg+cN3/wQ== +-----END CERTIFICATE----- diff --git a/tests/suites/test_suite_x509parse.data b/tests/suites/test_suite_x509parse.data index 0fe68cb06..e39f065e2 100644 --- a/tests/suites/test_suite_x509parse.data +++ b/tests/suites/test_suite_x509parse.data @@ -1798,6 +1798,12 @@ X509 File parse (trailing spaces, OK) depends_on:MBEDTLS_ECDSA_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED:MBEDTLS_SHA256_C:MBEDTLS_RSA_C x509parse_crt_file:"data_files/server7_trailing_space.crt":0 +X509 File parse (unsupported critical ext Name Constraints, fail) +x509parse_crt_file:"data_files/test-ca-nc.crt":MBEDTLS_ERR_X509_INVALID_EXTENSIONS + MBEDTLS_ERR_ASN1_UNEXPECTED_TAG + +X509 File parse (allowed unsupported critical ext Name Constraints, ok) +x509parse_crt_file_allow_exts:"data_files/test-ca-nc.crt":MBEDTLS_X509_EXT_NAME_CONSTRAINTS:0 + X509 Get time (UTC no issues) depends_on:MBEDTLS_X509_USE_C x509_get_time:MBEDTLS_ASN1_UTC_TIME:"500101000000Z":0:1950:1:1:0:0:0 diff --git a/tests/suites/test_suite_x509parse.function b/tests/suites/test_suite_x509parse.function index 584ee822b..c12a0e0ef 100644 --- a/tests/suites/test_suite_x509parse.function +++ b/tests/suites/test_suite_x509parse.function @@ -448,6 +448,21 @@ exit: } /* END_CASE */ +/* BEGIN_CASE depends_on:MBEDTLS_X509_CRT_PARSE_C:MBEDTLS_FS_IO */ +void x509parse_crt_file_allow_exts( char *crt_file, int exts, int result ) +{ + mbedtls_x509_crt crt; + + mbedtls_x509_crt_init( &crt ); + crt.allowed_unsupported_critical_exts = exts; + + TEST_ASSERT( mbedtls_x509_crt_parse_file( &crt, crt_file ) == result ); + +exit: + mbedtls_x509_crt_free( &crt ); +} +/* END_CASE */ + /* BEGIN_CASE depends_on:MBEDTLS_X509_CRT_PARSE_C */ void x509parse_crt( char *crt_data, char *result_str, int result ) { -- 2.22.0.windows.1