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Use in-place decryption in pk_parse_pkcs8_encrypted_der
The stack buffer used to hold the decrypted key in pk_parse_pkcs8_encrypted_der was statically sized to 2048 bytes, which is not enough for DER encoded 4096bit RSA keys. This commit resolves the problem by performing the key-decryption in-place, circumventing the introduction of another stack or heap copy of the key. There are two situations where pk_parse_pkcs8_encrypted_der is invoked: 1. When processing a PEM-encoded encrypted key in pk_parse_key. This does not need adaption since the PEM context used to hold the decoded key is already constructed and owned by pk_parse_key. 2. When processing a DER-encoded encrypted key in pk_parse_key. In this case, pk_parse_key calls pk_parse_pkcs8_encrypted_der with the buffer provided by the user, which is declared const. The commit therefore adds a small code paths making a copy of the keybuffer before calling pk_parse_pkcs8_encrypted_der.
This commit is contained in:
parent
a75a459143
commit
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@ -930,12 +930,12 @@ static int pk_parse_key_pkcs8_unencrypted_der(
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#if defined(POLARSSL_PKCS12_C) || defined(POLARSSL_PKCS5_C)
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static int pk_parse_key_pkcs8_encrypted_der(
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pk_context *pk,
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const unsigned char *key, size_t keylen,
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unsigned char *key, size_t keylen,
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const unsigned char *pwd, size_t pwdlen )
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{
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int ret, decrypted = 0;
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size_t len;
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unsigned char buf[2048];
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unsigned char *buf;
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unsigned char *p, *end;
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asn1_buf pbe_alg_oid, pbe_params;
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#if defined(POLARSSL_PKCS12_C)
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@ -943,8 +943,6 @@ static int pk_parse_key_pkcs8_encrypted_der(
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md_type_t md_alg;
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#endif
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memset( buf, 0, sizeof( buf ) );
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p = (unsigned char *) key;
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end = p + keylen;
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@ -979,8 +977,7 @@ static int pk_parse_key_pkcs8_encrypted_der(
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if( ( ret = asn1_get_tag( &p, end, &len, ASN1_OCTET_STRING ) ) != 0 )
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return( POLARSSL_ERR_PK_KEY_INVALID_FORMAT + ret );
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if( len > sizeof( buf ) )
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return( POLARSSL_ERR_PK_BAD_INPUT_DATA );
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buf = p;
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/*
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* Decrypt EncryptedData with appropriate PDE
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@ -1170,12 +1167,24 @@ int pk_parse_key( pk_context *pk,
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* error
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*/
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#if defined(POLARSSL_PKCS12_C) || defined(POLARSSL_PKCS5_C)
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if( ( ret = pk_parse_key_pkcs8_encrypted_der( pk, key, keylen,
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pwd, pwdlen ) ) == 0 )
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{
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return( 0 );
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unsigned char *key_copy;
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if( ( key_copy = polarssl_malloc( keylen ) ) == NULL )
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return( POLARSSL_ERR_PK_MALLOC_FAILED );
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memcpy( key_copy, key, keylen );
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ret = pk_parse_key_pkcs8_encrypted_der( pk, key_copy, keylen,
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pwd, pwdlen );
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polarssl_zeroize( key_copy, keylen );
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polarssl_free( key_copy );
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}
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if( ret == 0 )
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return( 0 );
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pk_free( pk );
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if( ret == POLARSSL_ERR_PK_PASSWORD_MISMATCH )
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