- Added CRL revocation support to x509parse_verify()

- Fixed an off-by-one allocation in ssl_set_hostname()
 - Added CRL support to SSL/TLS code

ChangeLog

@@ -18,6 +18,10 @@ PolarSSL ChangeLog
      systems (Found by Gernot).
    * Undefining POLARSSL_HAVE_ASM now also handles prevents asm in
      padlock and timing code. 
+   * Fixed an off-by-one buffer allocation in ssl_set_hostname().
+   * Added support for Certificate Revocation List (CRL parsing.
+   * Added support for CRL revocation to x509parse_verify() and
+     SSL/TLS code.
 
 = Version 0.10.0 released on 2009-01-12
    * Migrated XySSL to PolarSSL

include/polarssl/ssl.h

@@ -235,6 +235,7 @@ struct _ssl_context
     rsa_context *rsa_key;               /*!<  own RSA private key     */
     x509_cert *own_cert;                /*!<  own X.509 certificate   */
     x509_cert *ca_chain;                /*!<  own trusted CA chain    */
+    x509_crl *ca_crl;                   /*!<  trusted CA CRLs         */
     x509_cert *peer_cert;               /*!<  peer X.509 cert chain   */
     char *peer_cn;                      /*!<  expected peer CN        */
 
@@ -389,12 +390,13 @@ void ssl_set_ciphers( ssl_context *ssl, int *ciphers );
  *
  * \param ssl      SSL context
  * \param ca_chain trusted CA chain
+ * \param ca_crl   trusted CA CRLs
  * \param peer_cn  expected peer CommonName (or NULL)
  *
  * \note           TODO: add two more parameters: depth and crl
  */
 void ssl_set_ca_chain( ssl_context *ssl, x509_cert *ca_chain,
-                       char *peer_cn );
+                       x509_crl *ca_crl, char *peer_cn );
 
 /**
  * \brief          Set own certificate and private key

include/polarssl/x509.h

@@ -60,6 +60,8 @@
 #define BADCERT_REVOKED                 2
 #define BADCERT_CN_MISMATCH             4
 #define BADCERT_NOT_TRUSTED             8
+#define BADCRL_NOT_TRUSTED             16
+#define BADCRL_EXPIRED                 32
 
 /*
  * DER constants
@@ -335,16 +337,17 @@ int x509parse_cert_info( char *buf, size_t size, char *prefix, x509_cert *crt );
 int x509parse_crl_info( char *buf, size_t size, char *prefix, x509_crl *crl );
 
 /**
- * \brief          Return 0 if the certificate is still valid,
+ * \brief          Return 0 if the x509_time is still valid,
- *                 or BADCERT_EXPIRED
+ *                 or 1 otherwise.
  */
-int x509parse_expired( x509_cert *crt );
+int x509parse_time_expired( x509_time *time );
 
 /**
  * \brief          Verify the certificate signature
  *
  * \param crt      a certificate to be verified
  * \param trust_ca the trusted CA chain
+ * \param ca_crl   the CRL chain for trusted CA's
  * \param cn       expected Common Name (can be set to
  *                 NULL if the CN must not be verified)
  * \param flags    result of the verification
@@ -361,6 +364,7 @@ int x509parse_expired( x509_cert *crt );
  */
 int x509parse_verify( x509_cert *crt,
                       x509_cert *trust_ca,
+                      x509_crl *ca_crl,
                       char *cn, int *flags );
 
 /**

library/ssl_tls.c

@@ -1332,7 +1332,7 @@ int ssl_parse_certificate( ssl_context *ssl )
             return( POLARSSL_ERR_SSL_CA_CHAIN_REQUIRED );
         }
 
-        ret = x509parse_verify( ssl->peer_cert, ssl->ca_chain,
+        ret = x509parse_verify( ssl->peer_cert, ssl->ca_chain, ssl->ca_crl,
                                 ssl->peer_cn,  &ssl->verify_result );
 
         if( ret != 0 )
@@ -1702,9 +1702,10 @@ void ssl_set_ciphers( ssl_context *ssl, int *ciphers )
 }
 
 void ssl_set_ca_chain( ssl_context *ssl, x509_cert *ca_chain,
-                       char *peer_cn )
+                       x509_crl *ca_crl, char *peer_cn )
 {
     ssl->ca_chain   = ca_chain;
+    ssl->ca_crl     = ca_crl;
     ssl->peer_cn    = peer_cn;
 }
 
@@ -1740,11 +1741,13 @@ int ssl_set_hostname( ssl_context *ssl, char *hostname )
         return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
 
     ssl->hostname_len = strlen( hostname );
-    ssl->hostname = (unsigned char *) malloc( ssl->hostname_len );
+    ssl->hostname = (unsigned char *) malloc( ssl->hostname_len + 1 );
 
     memcpy( ssl->hostname, (unsigned char *) hostname,
             ssl->hostname_len );
     
+    ssl->hostname[ssl->hostname_len] = '\0';
+
     return( 0 );
 }
 

library/x509parse.c

@@ -2068,9 +2068,9 @@ int x509parse_crl_info( char *buf, size_t size, char *prefix, x509_crl *crl )
 }
 
 /*
- * Return 0 if the certificate is still valid, or BADCERT_EXPIRED
+ * Return 0 if the x509_time is still valid, or 1 otherwise.
  */
-int x509parse_expired( x509_cert *crt )
+int x509parse_time_expired( x509_time *to )
 {
     struct tm *lt;
     time_t tt;
@@ -2078,17 +2078,38 @@ int x509parse_expired( x509_cert *crt )
     tt = time( NULL );
     lt = localtime( &tt );
 
-    if( lt->tm_year  > crt->valid_to.year - 1900 )
+    if( lt->tm_year  > to->year - 1900 )
-        return( BADCERT_EXPIRED );
+        return( 1 );
 
-    if( lt->tm_year == crt->valid_to.year - 1900 &&
+    if( lt->tm_year == to->year - 1900 &&
-        lt->tm_mon   > crt->valid_to.mon  - 1 )
+        lt->tm_mon   > to->mon  - 1 )
-        return( BADCERT_EXPIRED );
+        return( 1 );
 
-    if( lt->tm_year == crt->valid_to.year - 1900 &&
+    if( lt->tm_year == to->year - 1900 &&
-        lt->tm_mon  == crt->valid_to.mon  - 1    &&
+        lt->tm_mon  == to->mon  - 1    &&
-        lt->tm_mday  > crt->valid_to.day )
+        lt->tm_mday  > to->day )
-        return( BADCERT_EXPIRED );
+        return( 1 );
+
+    return( 0 );
+}
+
+/*
+ * Return 1 if the certificate is revoked, or 0 otherwise.
+ */
+int x509parse_revoked( x509_cert *crt, x509_crl *crl )
+{
+    x509_crl_entry *cur = &crl->entry;
+
+    while( cur != NULL && cur->serial.len != 0 )
+    {
+        if( memcmp( crt->serial.p, cur->serial.p, crt->serial.len ) == 0 )
+        {
+            if( x509parse_time_expired( &cur->revocation_date ) )
+                return( 1 );
+        }
+
+        cur = cur->next;
+    }
 
     return( 0 );
 }
@@ -2125,6 +2146,7 @@ static void x509_hash( unsigned char *in, int len, int alg,
  */
 int x509parse_verify( x509_cert *crt,
                       x509_cert *trust_ca,
+                      x509_crl *ca_crl,
                       char *cn, int *flags )
 {
     int cn_len;
@@ -2134,7 +2156,10 @@ int x509parse_verify( x509_cert *crt,
     x509_name *name;
     unsigned char hash[64];
 
-    *flags = x509parse_expired( crt );
+    *flags = 0;
+
+    if( x509parse_time_expired( &crt->valid_to ) )
+        *flags = BADCERT_EXPIRED;
 
     if( cn != NULL )
     {
@@ -2224,6 +2249,61 @@ int x509parse_verify( x509_cert *crt,
         trust_ca = trust_ca->next;
     }
 
+    /*
+     * TODO: What happens if no CRL is present?
+     * Suggestion: Revocation state should be unknown if no CRL is present.
+     * For backwards compatibility this is not yet implemented.
+     */
+
+    /*
+     * Check if the topmost certificate is revoked if the trusted CA is
+     * determined.
+     */
+    while( trust_ca != NULL && ca_crl != NULL && ca_crl->version != 0 )
+    {
+        if( ca_crl->issuer_raw.len != trust_ca->subject_raw.len ||
+            memcmp( ca_crl->issuer_raw.p, trust_ca->subject_raw.p,
+                    ca_crl->issuer_raw.len ) != 0 )
+        {
+            ca_crl = ca_crl->next;
+            continue;
+        }
+
+        /*
+         * Check if CRL is correctry signed by the trusted CA
+         */
+        hash_id = ca_crl->sig_oid1.p[8];
+
+        x509_hash( ca_crl->tbs.p, ca_crl->tbs.len, hash_id, hash );
+
+        if( !rsa_pkcs1_verify( &trust_ca->rsa, RSA_PUBLIC, hash_id,
+                              0, hash, ca_crl->sig.p ) == 0 )
+        {
+            /*
+             * CRL is not trusted
+             */
+            *flags |= BADCRL_NOT_TRUSTED;
+            break;
+        }
+
+        /*
+         * Check for validity of CRL (Do not drop out)
+         */
+        if( x509parse_time_expired( &ca_crl->next_update ) )
+            *flags |= BADCRL_EXPIRED;
+        
+        /*
+         * Check if certificate is revoked
+         */
+        if( x509parse_revoked(crt, ca_crl) )
+        {
+            *flags |= BADCERT_REVOKED;
+            break;
+        }
+
+        ca_crl = ca_crl->next;
+    }
+
     if( *flags != 0 )
         return( POLARSSL_ERR_X509_CERT_VERIFY_FAILED );
 
@@ -2406,7 +2486,7 @@ int x509_self_test( int verbose )
     if( verbose != 0 )
         printf( "passed\n  X.509 signature verify: ");
 
-    ret = x509parse_verify( &clicert, &cacert, "Joe User", &i );
+    ret = x509parse_verify( &clicert, &cacert, NULL, "Joe User", &i );
     if( ret != 0 )
     {
         if( verbose != 0 )

programs/ssl/ssl_client2.c

@@ -158,7 +158,7 @@ int main( void )
     ssl_set_ciphers( &ssl, ssl_default_ciphers );
     ssl_set_session( &ssl, 1, 600, &ssn );
 
-    ssl_set_ca_chain( &ssl, &cacert, SERVER_NAME );
+    ssl_set_ca_chain( &ssl, &cacert, NULL, SERVER_NAME );
     ssl_set_own_cert( &ssl, &clicert, &rsa );
 
     ssl_set_hostname( &ssl, SERVER_NAME );

programs/ssl/ssl_server.c

@@ -286,7 +286,7 @@ accept:
 
     memset( &ssn, 0, sizeof( ssl_session ) );
 
-    ssl_set_ca_chain( &ssl, srvcert.next, NULL );
+    ssl_set_ca_chain( &ssl, srvcert.next, NULL, NULL );
     ssl_set_own_cert( &ssl, &srvcert, &rsa );
     ssl_set_dh_param( &ssl, my_dhm_P, my_dhm_G );
 

programs/test/ssl_cert_test.c

@@ -32,12 +32,14 @@
 #define snprintf _snprintf
 #endif
 
-#define MAX_CLIENT_CERTS    6
+#define MAX_CLIENT_CERTS    8
 
 char *client_certificates[MAX_CLIENT_CERTS] =
 {
     "client1.crt",
     "client2.crt",
+    "server1.crt",
+    "server2.crt",
     "cert_sha224.crt",
     "cert_sha256.crt",
     "cert_sha384.crt",
@@ -48,6 +50,8 @@ char *client_private_keys[MAX_CLIENT_CERTS] =
 {
     "client1.key",
     "client2.key",
+    "server1.key",
+    "server2.key",
     "cert_sha224.key",
     "cert_sha256.key",
     "cert_sha384.key",
@@ -83,6 +87,9 @@ int main( void )
 
     printf( " ok\n" );
 
+    x509parse_cert_info( buf, 1024, "CRT: ", &cacert );
+    printf("%s\n", buf );
+
     /*
      * 1.2. Load the CRL
      */
@@ -134,12 +141,18 @@ int main( void )
         printf( "  . Verify the client certificate with CA certificate..." );
         fflush( stdout );
 
-        ret = x509parse_verify( &clicert, &cacert, NULL, &flags );
+        ret = x509parse_verify( &clicert, &cacert, &crl, NULL, &flags );
         if( ret != 0 )
         {
+            if( ret == POLARSSL_ERR_X509_CERT_VERIFY_FAILED )
+            {
+                if( flags == BADCERT_REVOKED )
+                    printf( " REVOKED " );
+            } else {
                 printf( " failed\n  !  x509parse_verify returned %d\n\n", ret );
                 goto exit;
             }
+        }
 
         printf( " ok\n" );
 

programs/test/ssl_test.c

@@ -225,7 +225,7 @@ static int ssl_test( struct options *opt )
 
         ssl_set_endpoint( &ssl, SSL_IS_SERVER );
         ssl_set_dh_param( &ssl, dhm_P, dhm_G );
-        ssl_set_ca_chain( &ssl, srvcert.next, NULL );
+        ssl_set_ca_chain( &ssl, srvcert.next, NULL, NULL );
         ssl_set_own_cert( &ssl, &srvcert, &rsa );
     }