Merge pull request #3048 from mpg/fix-rsa-complete-2.16
[backport 2.16] Fix pk_parse_key()'s use of rsa_complete()
diff --git a/ChangeLog b/ChangeLog
index f6d3124..bc2a7c8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -17,6 +17,11 @@
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 0ae2402..d500457 100644
--- a/library/pkparse.c
+++ b/library/pkparse.c
@@ -678,6 +678,32 @@
#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
*/
static int pk_parse_key_pkcs1_der( mbedtls_rsa_context *rsa,
@@ -729,46 +755,36 @@
}
/* 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 @@
*/
/* 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 4add252..cd842cf 100644
--- a/tests/suites/test_suite_pkparse.data
+++ b/tests/suites/test_suite_pkparse.data
@@ -1072,33 +1072,84 @@
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 3eb0397..4650d33 100644
--- a/tests/suites/test_suite_pkparse.function
+++ b/tests/suites/test_suite_pkparse.function
@@ -113,23 +113,14 @@
}
/* 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 );
