diff --git a/ChangeLog b/ChangeLog index f6d31246db..bc2a7c8061 100644 --- a/ChangeLog +++ b/ChangeLog @@ -17,6 +17,11 @@ Security Bugfix * Fix an unchecked call to mbedtls_md() in the x509write module. + * Fix a bug in mbedtls_pk_parse_key() that would cause it to accept some + RSA keys that would later be rejected by functions expecting private + keys. Found by Catena cyber using oss-fuzz (issue 20467). + * Fix a bug in mbedtls_pk_parse_key() that would cause it to accept some + RSA keys with invalid values by silently fixing those values. = mbed TLS 2.16.4 branch released 2020-01-15 diff --git a/library/pkparse.c b/library/pkparse.c index 0ae24027fe..d5004577a1 100644 --- a/library/pkparse.c +++ b/library/pkparse.c @@ -677,6 +677,32 @@ int mbedtls_pk_parse_subpubkey( unsigned char **p, const unsigned char *end, } #if defined(MBEDTLS_RSA_C) +/* + * Wrapper around mbedtls_asn1_get_mpi() that rejects zero. + * + * The value zero is: + * - never a valid value for an RSA parameter + * - interpreted as "omitted, please reconstruct" by mbedtls_rsa_complete(). + * + * Since values can't be omitted in PKCS#1, passing a zero value to + * rsa_complete() would be incorrect, so reject zero values early. + */ +static int asn1_get_nonzero_mpi( unsigned char **p, + const unsigned char *end, + mbedtls_mpi *X ) +{ + int ret; + + ret = mbedtls_asn1_get_mpi( p, end, X ); + if( ret != 0 ) + return( ret ); + + if( mbedtls_mpi_cmp_int( X, 0 ) == 0 ) + return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT ); + + return( 0 ); +} + /* * Parse a PKCS#1 encoded private RSA key */ @@ -729,46 +755,36 @@ static int pk_parse_key_pkcs1_der( mbedtls_rsa_context *rsa, } /* Import N */ - if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, - MBEDTLS_ASN1_INTEGER ) ) != 0 || - ( ret = mbedtls_rsa_import_raw( rsa, p, len, NULL, 0, NULL, 0, - NULL, 0, NULL, 0 ) ) != 0 ) + if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 || + ( ret = mbedtls_rsa_import( rsa, &T, NULL, NULL, + NULL, NULL ) ) != 0 ) goto cleanup; - p += len; /* Import E */ - if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, - MBEDTLS_ASN1_INTEGER ) ) != 0 || - ( ret = mbedtls_rsa_import_raw( rsa, NULL, 0, NULL, 0, NULL, 0, - NULL, 0, p, len ) ) != 0 ) + if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 || + ( ret = mbedtls_rsa_import( rsa, NULL, NULL, NULL, + NULL, &T ) ) != 0 ) goto cleanup; - p += len; /* Import D */ - if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, - MBEDTLS_ASN1_INTEGER ) ) != 0 || - ( ret = mbedtls_rsa_import_raw( rsa, NULL, 0, NULL, 0, NULL, 0, - p, len, NULL, 0 ) ) != 0 ) + if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 || + ( ret = mbedtls_rsa_import( rsa, NULL, NULL, NULL, + &T, NULL ) ) != 0 ) goto cleanup; - p += len; /* Import P */ - if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, - MBEDTLS_ASN1_INTEGER ) ) != 0 || - ( ret = mbedtls_rsa_import_raw( rsa, NULL, 0, p, len, NULL, 0, - NULL, 0, NULL, 0 ) ) != 0 ) + if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 || + ( ret = mbedtls_rsa_import( rsa, NULL, &T, NULL, + NULL, NULL ) ) != 0 ) goto cleanup; - p += len; /* Import Q */ - if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, - MBEDTLS_ASN1_INTEGER ) ) != 0 || - ( ret = mbedtls_rsa_import_raw( rsa, NULL, 0, NULL, 0, p, len, - NULL, 0, NULL, 0 ) ) != 0 ) + if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 || + ( ret = mbedtls_rsa_import( rsa, NULL, NULL, &T, + NULL, NULL ) ) != 0 ) goto cleanup; - p += len; -#if !defined(MBEDTLS_RSA_NO_CRT) +#if !defined(MBEDTLS_RSA_NO_CRT) && !defined(MBEDTLS_RSA_ALT) /* * The RSA CRT parameters DP, DQ and QP are nominally redundant, in * that they can be easily recomputed from D, P and Q. However by @@ -781,28 +797,42 @@ static int pk_parse_key_pkcs1_der( mbedtls_rsa_context *rsa, */ /* Import DP */ - if( ( ret = mbedtls_asn1_get_mpi( &p, end, &rsa->DP ) ) != 0) + if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 || + ( ret = mbedtls_mpi_copy( &rsa->DP, &T ) ) != 0 ) goto cleanup; /* Import DQ */ - if( ( ret = mbedtls_asn1_get_mpi( &p, end, &rsa->DQ ) ) != 0) + if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 || + ( ret = mbedtls_mpi_copy( &rsa->DQ, &T ) ) != 0 ) goto cleanup; /* Import QP */ - if( ( ret = mbedtls_asn1_get_mpi( &p, end, &rsa->QP ) ) != 0) + if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 || + ( ret = mbedtls_mpi_copy( &rsa->QP, &T ) ) != 0 ) goto cleanup; #else /* Verify existance of the CRT params */ - if( ( ret = mbedtls_asn1_get_mpi( &p, end, &T ) ) != 0 || - ( ret = mbedtls_asn1_get_mpi( &p, end, &T ) ) != 0 || - ( ret = mbedtls_asn1_get_mpi( &p, end, &T ) ) != 0 ) + if( ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 || + ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 || + ( ret = asn1_get_nonzero_mpi( &p, end, &T ) ) != 0 ) goto cleanup; #endif - /* Complete the RSA private key */ - if( ( ret = mbedtls_rsa_complete( rsa ) ) != 0 ) + /* rsa_complete() doesn't complete anything with the default + * implementation but is still called: + * - for the benefit of alternative implementation that may want to + * pre-compute stuff beyond what's provided (eg Montgomery factors) + * - as is also sanity-checks the key + * + * Furthermore, we also check the public part for consistency with + * mbedtls_pk_parse_pubkey(), as it includes size minima for example. + */ + if( ( ret = mbedtls_rsa_complete( rsa ) ) != 0 || + ( ret = mbedtls_rsa_check_pubkey( rsa ) ) != 0 ) + { goto cleanup; + } if( p != end ) { diff --git a/tests/suites/test_suite_pkparse.data b/tests/suites/test_suite_pkparse.data index 4add252df7..cd842cf8bd 100644 --- a/tests/suites/test_suite_pkparse.data +++ b/tests/suites/test_suite_pkparse.data @@ -1072,33 +1072,84 @@ Parse EC Key #15 (SEC1 DER, secp256k1, SpecifiedECDomain) depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_ECP_C:MBEDTLS_ECP_DP_SECP256K1_ENABLED:MBEDTLS_PK_PARSE_EC_EXTENDED pk_parse_keyfile_ec:"data_files/ec_prv.specdom.der":"NULL":0 -Key ASN1 (Incorrect first tag) -pk_parse_key:"":"":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +Key ASN1 (No data) +pk_parse_key:"":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + +Key ASN1 (First tag not Sequence) +pk_parse_key:"020100":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT Key ASN1 (RSAPrivateKey, incorrect version tag) depends_on:MBEDTLS_RSA_C -pk_parse_key:"300100":"":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +pk_parse_key:"300100":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT Key ASN1 (RSAPrivateKey, version tag missing) depends_on:MBEDTLS_RSA_C -pk_parse_key:"3000":"":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +pk_parse_key:"3000":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT Key ASN1 (RSAPrivateKey, invalid version) depends_on:MBEDTLS_RSA_C -pk_parse_key:"3003020101":"":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +pk_parse_key:"3003020101":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT Key ASN1 (RSAPrivateKey, correct version, incorrect tag) depends_on:MBEDTLS_RSA_C -pk_parse_key:"300402010000":"":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +pk_parse_key:"300402010000":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT -Key ASN1 (RSAPrivateKey, values present, length mismatch) +Key ASN1 (RSAPrivateKey, correct format+values, minimal modulus size (128 bit)) depends_on:MBEDTLS_RSA_C -pk_parse_key:"301c02010002010102010102010102010102010102010102010102010100":"":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +pk_parse_key:"3063020100021100cc8ab070369ede72920e5a51523c857102030100010211009a6318982a7231de1894c54aa4909201020900f3058fd8dc484d61020900d7770dbd8b78a2110209009471f14c26428401020813425f060c4b72210208052b93d01747a87c":0 -Key ASN1 (RSAPrivateKey, values present, check_privkey fails) +Key ASN1 (RSAPrivateKey, correct format, modulus too small (127 bit)) depends_on:MBEDTLS_RSA_C -pk_parse_key:"301b020100020102020101020101020101020101020101020101020101":"":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +pk_parse_key:"30630201000211007c8ab070369ede72920e5a51523c857102030100010211009a6318982a7231de1894c54aa4909201020900f3058fd8dc484d61020900d7770dbd8b78a2110209009471f14c26428401020813425f060c4b72210208052b93d01747a87c":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + +Key ASN1 (RSAPrivateKey, correct format, modulus even) +depends_on:MBEDTLS_RSA_C +pk_parse_key:"3063020100021100cc8ab070369ede72920e5a51523c857002030100010211009a6318982a7231de1894c54aa4909201020900f3058fd8dc484d61020900d7770dbd8b78a2110209009471f14c26428401020813425f060c4b72210208052b93d01747a87c":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + +Key ASN1 (RSAPrivateKey, correct format, d == 0) +depends_on:MBEDTLS_RSA_C +pk_parse_key:"30630201000211007c8ab070369ede72920e5a51523c8571020301000102110000000000000000000000000000000000020900f3058fd8dc484d61020900d7770dbd8b78a2110209009471f14c26428401020813425f060c4b72210208052b93d01747a87c":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + +Key ASN1 (RSAPrivateKey, correct format, d == p == q == 0) +depends_on:MBEDTLS_RSA_C +pk_parse_key:"3063020100021100cc8ab070369ede72920e5a51523c8571020301000102110000000000000000000000000000000000020900000000000000000002090000000000000000000209009471f14c26428401020813425f060c4b72210208052b93d01747a87c":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + +Key ASN1 (RSAPrivateKey, correct values, trailing garbage) +depends_on:MBEDTLS_RSA_C +pk_parse_key:"3064020100021100cc8ab070369ede72920e5a51523c857102030100010211009a6318982a7231de1894c54aa4909201020900f3058fd8dc484d61020900d7770dbd8b78a2110209009471f14c26428401020813425f060c4b72210208052b93d01747a87c00":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + +Key ASN1 (RSAPrivateKey, correct values, n wrong tag) +depends_on:MBEDTLS_RSA_C +pk_parse_key:"3063020100FF1100cc8ab070369ede72920e5a51523c857102030100010211009a6318982a7231de1894c54aa4909201020900f3058fd8dc484d61020900d7770dbd8b78a2110209009471f14c26428401020813425f060c4b72210208052b93d01747a87c":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + +Key ASN1 (RSAPrivateKey, correct values, e wrong tag) +depends_on:MBEDTLS_RSA_C +pk_parse_key:"3063020100021100cc8ab070369ede72920e5a51523c8571FF030100010211009a6318982a7231de1894c54aa4909201020900f3058fd8dc484d61020900d7770dbd8b78a2110209009471f14c26428401020813425f060c4b72210208052b93d01747a87c":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + +Key ASN1 (RSAPrivateKey, correct values, d wrong tag) +depends_on:MBEDTLS_RSA_C +pk_parse_key:"3063020100021100cc8ab070369ede72920e5a51523c85710203010001FF11009a6318982a7231de1894c54aa4909201020900f3058fd8dc484d61020900d7770dbd8b78a2110209009471f14c26428401020813425f060c4b72210208052b93d01747a87c":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + +Key ASN1 (RSAPrivateKey, correct values, p wrong tag) +depends_on:MBEDTLS_RSA_C +pk_parse_key:"3063020100021100cc8ab070369ede72920e5a51523c857102030100010211009a6318982a7231de1894c54aa4909201FF0900f3058fd8dc484d61020900d7770dbd8b78a2110209009471f14c26428401020813425f060c4b72210208052b93d01747a87c":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + +Key ASN1 (RSAPrivateKey, correct values, q wrong tag) +depends_on:MBEDTLS_RSA_C +pk_parse_key:"3063020100021100cc8ab070369ede72920e5a51523c857102030100010211009a6318982a7231de1894c54aa4909201020900f3058fd8dc484d61FF0900d7770dbd8b78a2110209009471f14c26428401020813425f060c4b72210208052b93d01747a87c":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + +Key ASN1 (RSAPrivateKey, correct values, dp wrong tag) +depends_on:MBEDTLS_RSA_C +pk_parse_key:"3063020100021100cc8ab070369ede72920e5a51523c857102030100010211009a6318982a7231de1894c54aa4909201020900f3058fd8dc484d61020900d7770dbd8b78a211FF09009471f14c26428401020813425f060c4b72210208052b93d01747a87c":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + +Key ASN1 (RSAPrivateKey, correct values, dq wrong tag) +depends_on:MBEDTLS_RSA_C +pk_parse_key:"3063020100021100cc8ab070369ede72920e5a51523c857102030100010211009a6318982a7231de1894c54aa4909201020900f3058fd8dc484d61020900d7770dbd8b78a2110209009471f14c26428401FF0813425f060c4b72210208052b93d01747a87c":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + +Key ASN1 (RSAPrivateKey, correct values, qp wrong tag) +depends_on:MBEDTLS_RSA_C +pk_parse_key:"3063020100021100cc8ab070369ede72920e5a51523c857102030100010211009a6318982a7231de1894c54aa4909201020900f3058fd8dc484d61020900d7770dbd8b78a2110209009471f14c26428401020813425f060c4b7221FF08052b93d01747a87c":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT Key ASN1 (ECPrivateKey, empty parameters) depends_on:MBEDTLS_ECP_C -pk_parse_key:"30070201010400a000":"":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +pk_parse_key:"30070201010400a000":MBEDTLS_ERR_PK_KEY_INVALID_FORMAT diff --git a/tests/suites/test_suite_pkparse.function b/tests/suites/test_suite_pkparse.function index 3eb0397e6a..4650d33115 100644 --- a/tests/suites/test_suite_pkparse.function +++ b/tests/suites/test_suite_pkparse.function @@ -113,23 +113,14 @@ exit: } /* END_CASE */ -/* BEGIN_CASE depends_on:MBEDTLS_RSA_C */ -void pk_parse_key( data_t * buf, char * result_str, int result ) +/* BEGIN_CASE */ +void pk_parse_key( data_t * buf, int result ) { mbedtls_pk_context pk; - unsigned char output[2000]; - ((void) result_str); mbedtls_pk_init( &pk ); - memset( output, 0, 2000 ); - - - TEST_ASSERT( mbedtls_pk_parse_key( &pk, buf->x, buf->len, NULL, 0 ) == ( result ) ); - if( ( result ) == 0 ) - { - TEST_ASSERT( 1 ); - } + TEST_ASSERT( mbedtls_pk_parse_key( &pk, buf->x, buf->len, NULL, 0 ) == result ); exit: mbedtls_pk_free( &pk );