Merge remote-tracking branch 'restricted/1205' into mbedtls-1.3-restricted

* restricted/1205:
  Fix name, documentation & location of config flag
  Restrict MD5 in x509 certificates

ChangeLog

@@ -13,6 +13,8 @@ Security
      Found by Laurent Simon.
     Tighten parsing of RSA PKCS#1 v1.5 signatures, to avoid a
      potential Bleichenbacher/BERserk-style attack.
+   * Remove support for X509 certificates signed with MD5.
+     Issue raised by Harm Verhagen
 
 Bugfix
    * Fix insufficient support for signature-hash-algorithm extension,

include/polarssl/config.h

@@ -2366,6 +2366,29 @@
 /* X509 options */
 //#define POLARSSL_X509_MAX_INTERMEDIATE_CA   8   /**< Maximum number of intermediate CAs in a verification chain. */
 
+/**
+ * \def POLARSSL_X509_MIN_VERIFY_MD_ALG
+ *
+ * Minimal hash algorithm accepted in X.509 chain verification.
+ *
+ * The value should be one of the enumerations in md_type_t defined in md.h
+ * Only algorithms with a value equal or higher are accepted.
+ *
+ * typedef enum {
+ *      POLARSSL_MD_NONE=0,
+ *      POLARSSL_MD_MD2,
+ *      POLARSSL_MD_MD4,
+ *      POLARSSL_MD_MD5,
+ *      POLARSSL_MD_SHA1,
+ *      POLARSSL_MD_SHA224,
+ *      POLARSSL_MD_SHA256,
+ *      POLARSSL_MD_SHA384,
+ *      POLARSSL_MD_SHA512,
+ *      POLARSSL_MD_RIPEMD160,
+ *  } md_type_t;
+ */
+//#define POLARSSL_X509_MIN_VERIFY_MD_ALG  POLARSSL_MD_SHA1
+
 /* \} name SECTION: Module configuration options */
 
 #include "check_config.h"

library/x509_crt.c

@@ -76,6 +76,10 @@
 #endif /* !_WIN32 || EFIX64 || EFI32 */
 #endif
 
+#if !defined(POLARSSL_X509_MIN_VERIFY_MD_ALG)
+#define POLARSSL_X509_MIN_VERIFY_MD_ALG  POLARSSL_MD_SHA1
+#endif
+
 /* Implementation that should never be optimized out by the compiler */
 static void polarssl_zeroize( void *v, size_t n ) {
     volatile unsigned char *p = v; while( n-- ) *p++ = 0;
@@ -1435,6 +1439,18 @@ int x509_crt_verify_info( char *buf, size_t size, const char *prefix,
     return( (int) ( size - n ) );
 }
 
+/*
+ * Check md_alg against profile
+ * Return 0 if md_alg acceptable for this profile, -1 otherwise
+ */
+static int x509_check_md_alg( md_type_t md_alg )
+{
+    if( md_alg >= POLARSSL_X509_MIN_VERIFY_MD_ALG )
+        return( 0 );
+
+    return( -1 );
+}
+
 #if defined(POLARSSL_X509_CHECK_KEY_USAGE)
 int x509_crt_check_key_usage( const x509_crt *crt, int usage )
 {
@@ -1542,6 +1558,15 @@ static int x509_crt_verifycrl( x509_crt *crt, x509_crt *ca,
         }
 #endif
 
+        /*
+         * Check if CRL is signed with a valid MD
+         */
+        if( x509_check_md_alg( crl_list->sig_md ) != 0 )
+        {
+            flags |= BADCRL_NOT_TRUSTED;
+            break;
+        }
+
         /*
          * Check if CRL is correctly signed by the trusted CA
          */
@@ -1789,6 +1814,18 @@ static int x509_crt_verify_top(
      */
     *flags |= BADCERT_NOT_TRUSTED;
 
+    /*
+     * Check if certificate is signed with a valid MD
+     */
+    if( x509_check_md_alg( child->sig_md ) != 0 )
+    {
+        *flags |= BADCERT_NOT_TRUSTED;
+        /*
+         * not signed with a valid MD, no need to check trust_ca
+         */
+        trust_ca = NULL;
+    }
+
     md_info = md_info_from_type( child->sig_md );
     if( md_info == NULL )
     {
@@ -1926,6 +1963,12 @@ static int x509_crt_verify_child(
     if( x509_time_future( &child->valid_from ) )
         *flags |= BADCERT_FUTURE;
 
+    /*
+     * Check if certificate is signed with a valid MD
+     */
+    if( x509_check_md_alg( child->sig_md ) != 0 )
+        *flags |= BADCERT_NOT_TRUSTED;
+
     md_info = md_info_from_type( child->sig_md );
     if( md_info == NULL )
     {

tests/suites/test_suite_x509parse.data

@@ -417,11 +417,11 @@ x509_verify:"data_files/server2.crt":"data_files/server1.crt":"data_files/crl_ex
 
 X509 Certificate verification #12 (Valid Cert MD4 Digest)
 depends_on:POLARSSL_MD4_C:POLARSSL_PEM_PARSE_C:POLARSSL_SHA1_C:POLARSSL_RSA_C:POLARSSL_PKCS1_V15
-x509_verify:"data_files/cert_md4.crt":"data_files/test-ca.crt":"data_files/crl.pem":"NULL":0:0:"NULL"
+x509_verify:"data_files/cert_md4.crt":"data_files/test-ca.crt":"data_files/crl.pem":"NULL":POLARSSL_ERR_X509_CERT_VERIFY_FAILED:BADCERT_NOT_TRUSTED:"NULL"
 
 X509 Certificate verification #13 (Valid Cert MD5 Digest)
 depends_on:POLARSSL_MD5_C:POLARSSL_PEM_PARSE_C:POLARSSL_SHA1_C:POLARSSL_RSA_C:POLARSSL_PKCS1_V15
-x509_verify:"data_files/cert_md5.crt":"data_files/test-ca.crt":"data_files/crl.pem":"NULL":0:0:"NULL"
+x509_verify:"data_files/cert_md5.crt":"data_files/test-ca.crt":"data_files/crl.pem":"NULL":POLARSSL_ERR_X509_CERT_VERIFY_FAILED:BADCERT_NOT_TRUSTED:"NULL"
 
 X509 Certificate verification #14 (Valid Cert SHA1 Digest)
 depends_on:POLARSSL_SHA1_C:POLARSSL_PEM_PARSE_C:POLARSSL_SHA1_C:POLARSSL_RSA_C:POLARSSL_PKCS1_V15
@@ -723,6 +723,14 @@ X509 Certificate verification #87 (Expired CA and invalid CA)
 depends_on:POLARSSL_PEM_PARSE_C:POLARSSL_ECP_C:POLARSSL_ECP_DP_SECP256R1_ENABLED:POLARSSL_ECP_DP_SECP384R1_ENABLED:POLARSSL_SHA1_C:POLARSSL_SHA256_C
 x509_verify:"data_files/server5.crt":"data_files/test-ca2_cat-past-invalid.crt":"data_files/crl-ec-sha1.pem":"NULL":POLARSSL_ERR_X509_CERT_VERIFY_FAILED:BADCERT_EXPIRED:"NULL"
 
+X509 Certificate verification #88 (MD4 CRL)
+depends_on:POLARSSL_SHA256_C:POLARSSL_PEM_PARSE_C:POLARSSL_SHA1_C:POLARSSL_RSA_C:POLARSSL_PKCS1_V15
+x509_verify:"data_files/cert_sha256.crt":"data_files/test-ca.crt":"data_files/crl_md4.pem":"NULL":POLARSSL_ERR_X509_CERT_VERIFY_FAILED:BADCRL_NOT_TRUSTED:"NULL"
+
+X509 Certificate verification #89 (MD5 CRL)
+depends_on:POLARSSL_SHA256_C:POLARSSL_PEM_PARSE_C:POLARSSL_SHA1_C:POLARSSL_RSA_C:POLARSSL_PKCS1_V15
+x509_verify:"data_files/cert_sha256.crt":"data_files/test-ca.crt":"data_files/crl_md5.pem":"NULL":POLARSSL_ERR_X509_CERT_VERIFY_FAILED:BADCRL_NOT_TRUSTED:"NULL"
+
 X509 Certificate verification callback: trusted EE cert
 depends_on:POLARSSL_PEM_PARSE_C:POLARSSL_ECDSA_C:POLARSSL_SHA256_C:POLARSSL_ECP_DP_SECP256R1_ENABLED
 x509_verify_callback:"data_files/server5-selfsigned.crt":"data_files/server5-selfsigned.crt":0:"depth 0 - serial 53\:A2\:CB\:4B\:12\:4E\:AD\:83\:7D\:A8\:94\:B2 - subject CN=selfsigned, OU=testing, O=PolarSSL, C=NL\n"