Merge remote-tracking branch 'origin/pr/2411' into development

ChangeLog

@@ -2,6 +2,16 @@ mbed TLS ChangeLog (Sorted per branch, date)
 
 = mbed TLS 2.x.x branch released xxxx-xx-xx
 
+Features
+   * Add a new X.509 API call `mbedtls_x509_parse_der_nocopy()`
+     which allows copy-less parsing of DER encoded X.509 CRTs,
+     at the cost of additional lifetime constraints on the input
+     buffer, but at the benefit of reduced RAM consumption.
+
+API Changes
+   * Add a new X.509 API call `mbedtls_x509_parse_der_nocopy()`.
+     See the Features section for more information.
+
 Bugfix
    * Fix a compilation issue with mbedtls_ecp_restart_ctx not being defined
      when MBEDTLS_ECP_ALT is defined. Reported by jwhui. Fixes #2242.

include/mbedtls/x509_crt.h

@@ -52,6 +52,8 @@ extern "C" {
  */
 typedef struct mbedtls_x509_crt
 {
+    int own_buffer;                     /**< Indicates if \c raw is owned
+                                         *   by the structure or not.        */
     mbedtls_x509_buf raw;               /**< The raw certificate data (DER). */
     mbedtls_x509_buf tbs;               /**< The raw certificate body (DER). The part that is To Be Signed. */
 
@@ -220,16 +222,58 @@ extern const mbedtls_x509_crt_profile mbedtls_x509_crt_profile_suiteb;
 
 /**
  * \brief          Parse a single DER formatted certificate and add it
- *                 to the chained list.
+ *                 to the end of the provided chained list.
  *
- * \param chain    points to the start of the chain
+ * \param chain    The pointer to the start of the CRT chain to attach to.
- * \param buf      buffer holding the certificate DER data
+ *                 When parsing the first CRT in a chain, this should point
- * \param buflen   size of the buffer
+ *                 to an instance of ::mbedtls_x509_crt initialized through
+ *                 mbedtls_x509_crt_init().
+ * \param buf      The buffer holding the DER encoded certificate.
+ * \param buflen   The size in Bytes of \p buf.
  *
- * \return         0 if successful, or a specific X509 or PEM error code
+ * \note           This function makes an internal copy of the CRT buffer
+ *                 \p buf. In particular, \p buf may be destroyed or reused
+ *                 after this call returns. To avoid duplicating the CRT
+ *                 buffer (at the cost of stricter lifetime constraints),
+ *                 use mbedtls_x509_crt_parse_der_nocopy() instead.
+ *
+ * \return         \c 0 if successful.
+ * \return         A negative error code on failure.
  */
-int mbedtls_x509_crt_parse_der( mbedtls_x509_crt *chain, const unsigned char *buf,
+int mbedtls_x509_crt_parse_der( mbedtls_x509_crt *chain,
-                        size_t buflen );
+                                const unsigned char *buf,
+                                size_t buflen );
+
+/**
+ * \brief          Parse a single DER formatted certificate and add it
+ *                 to the end of the provided chained list. This is a
+ *                 variant of mbedtls_x509_crt_parse_der() which takes
+ *                 temporary ownership of the CRT buffer until the CRT
+ *                 is destroyed.
+ *
+ * \param chain    The pointer to the start of the CRT chain to attach to.
+ *                 When parsing the first CRT in a chain, this should point
+ *                 to an instance of ::mbedtls_x509_crt initialized through
+ *                 mbedtls_x509_crt_init().
+ * \param buf      The address of the readable buffer holding the DER encoded
+ *                 certificate to use. On success, this buffer must be
+ *                 retained and not be changed for the liftetime of the
+ *                 CRT chain \p chain, that is, until \p chain is destroyed
+ *                 through a call to mbedtls_x509_crt_free().
+ * \param buflen   The size in Bytes of \p buf.
+ *
+ * \note           This call is functionally equivalent to
+ *                 mbedtls_x509_crt_parse_der(), but it avoids creating a
+ *                 copy of the input buffer at the cost of stronger lifetime
+ *                 constraints. This is useful in constrained environments
+ *                 where duplication of the CRT cannot be tolerated.
+ *
+ * \return         \c 0 if successful.
+ * \return         A negative error code on failure.
+ */
+int mbedtls_x509_crt_parse_der_nocopy( mbedtls_x509_crt *chain,
+                                       const unsigned char *buf,
+                                       size_t buflen );
 
 /**
  * \brief          Parse one DER-encoded or one or more concatenated PEM-encoded

library/x509_crt.c

@@ -834,8 +834,10 @@ static int x509_get_crt_ext( unsigned char **p,
 /*
  * Parse and fill a single X.509 certificate in DER format
  */
-static int x509_crt_parse_der_core( mbedtls_x509_crt *crt, const unsigned char *buf,
+static int x509_crt_parse_der_core( mbedtls_x509_crt *crt,
-                                    size_t buflen )
+                                    const unsigned char *buf,
+                                    size_t buflen,
+                                    int make_copy )
 {
     int ret;
     size_t len;
@@ -852,7 +854,7 @@ static int x509_crt_parse_der_core( mbedtls_x509_crt *crt, const unsigned char *
     if( crt == NULL || buf == NULL )
         return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
 
-    // Use the original buffer until we figure out actual length
+    /* Use the original buffer until we figure out actual length. */
     p = (unsigned char*) buf;
     len = buflen;
     end = p + len;
@@ -870,25 +872,26 @@ static int x509_crt_parse_der_core( mbedtls_x509_crt *crt, const unsigned char *
         return( MBEDTLS_ERR_X509_INVALID_FORMAT );
     }
 
-    if( len > (size_t) ( end - p ) )
-    {
-        mbedtls_x509_crt_free( crt );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
-    }
-    crt_end = p + len;
-
-    // Create and populate a new buffer for the raw field
-    crt->raw.len = crt_end - buf;
-    crt->raw.p = p = mbedtls_calloc( 1, crt->raw.len );
-    if( p == NULL )
-        return( MBEDTLS_ERR_X509_ALLOC_FAILED );
-
-    memcpy( p, buf, crt->raw.len );
-
-    // Direct pointers to the new buffer
-    p += crt->raw.len - len;
     end = crt_end = p + len;
+    crt->raw.len = crt_end - buf;
+    if( make_copy != 0 )
+    {
+        /* Create and populate a new buffer for the raw field. */
+        crt->raw.p = p = mbedtls_calloc( 1, crt->raw.len );
+        if( crt->raw.p == NULL )
+            return( MBEDTLS_ERR_X509_ALLOC_FAILED );
+
+        memcpy( crt->raw.p, buf, crt->raw.len );
+        crt->own_buffer = 1;
+
+        p += crt->raw.len - len;
+        end = crt_end = p + len;
+    }
+    else
+    {
+        crt->raw.p = (unsigned char*) buf;
+        crt->own_buffer = 0;
+    }
 
     /*
      * TBSCertificate  ::=  SEQUENCE  {
@@ -1091,8 +1094,10 @@ static int x509_crt_parse_der_core( mbedtls_x509_crt *crt, const unsigned char *
  * Parse one X.509 certificate in DER format from a buffer and add them to a
  * chained list
  */
-int mbedtls_x509_crt_parse_der( mbedtls_x509_crt *chain, const unsigned char *buf,
+static int mbedtls_x509_crt_parse_der_internal( mbedtls_x509_crt *chain,
-                        size_t buflen )
+                                                const unsigned char *buf,
+                                                size_t buflen,
+                                                int make_copy )
 {
     int ret;
     mbedtls_x509_crt *crt = chain, *prev = NULL;
@@ -1124,7 +1129,7 @@ int mbedtls_x509_crt_parse_der( mbedtls_x509_crt *chain, const unsigned char *bu
         crt = crt->next;
     }
 
-    if( ( ret = x509_crt_parse_der_core( crt, buf, buflen ) ) != 0 )
+    if( ( ret = x509_crt_parse_der_core( crt, buf, buflen, make_copy ) ) != 0 )
     {
         if( prev )
             prev->next = NULL;
@@ -1138,11 +1143,27 @@ int mbedtls_x509_crt_parse_der( mbedtls_x509_crt *chain, const unsigned char *bu
     return( 0 );
 }
 
+int mbedtls_x509_crt_parse_der_nocopy( mbedtls_x509_crt *chain,
+                                       const unsigned char *buf,
+                                       size_t buflen )
+{
+    return( mbedtls_x509_crt_parse_der_internal( chain, buf, buflen, 0 ) );
+}
+
+int mbedtls_x509_crt_parse_der( mbedtls_x509_crt *chain,
+                                const unsigned char *buf,
+                                size_t buflen )
+{
+    return( mbedtls_x509_crt_parse_der_internal( chain, buf, buflen, 1 ) );
+}
+
 /*
  * Parse one or more PEM certificates from a buffer and add them to the chained
  * list
  */
-int mbedtls_x509_crt_parse( mbedtls_x509_crt *chain, const unsigned char *buf, size_t buflen )
+int mbedtls_x509_crt_parse( mbedtls_x509_crt *chain,
+                            const unsigned char *buf,
+                            size_t buflen )
 {
 #if defined(MBEDTLS_PEM_PARSE_C)
     int success = 0, first_error = 0, total_failed = 0;
@@ -2699,7 +2720,7 @@ void mbedtls_x509_crt_free( mbedtls_x509_crt *crt )
             mbedtls_free( seq_prv );
         }
 
-        if( cert_cur->raw.p != NULL )
+        if( cert_cur->raw.p != NULL && cert_cur->own_buffer )
         {
             mbedtls_platform_zeroize( cert_cur->raw.p, cert_cur->raw.len );
             mbedtls_free( cert_cur->raw.p );

tests/data_files/Makefile

@@ -45,7 +45,9 @@ all_intermediate += test-ca.req.sha256
 
 test-ca.crt: $(test_ca_key_file_rsa) test-ca.req.sha256
 	$(MBEDTLS_CERT_WRITE) is_ca=1 serial=3 request_file=test-ca.req.sha256 selfsign=1 issuer_name="C=NL,O=PolarSSL,CN=PolarSSL Test CA" issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) not_before=20110212144400 not_after=20210212144400 md=SHA1 version=3 output_file=$@
-all_final += test-ca.crt
+test-ca.der: test-ca.crt
+	$(OPENSSL) x509 -inform PEM -in $< -outform DER -out $@
+all_final += test-ca.crt test-ca.der
 
 test-ca-sha1.crt: $(test_ca_key_file_rsa) test-ca.req.sha256
 	$(MBEDTLS_CERT_WRITE) is_ca=1 serial=3 request_file=test-ca.req.sha256 selfsign=1 issuer_name="C=NL,O=PolarSSL,CN=PolarSSL Test CA" issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) not_before=20110212144400 not_after=20210212144400 md=SHA1 version=3 output_file=$@
@@ -873,7 +875,9 @@ server1_all: server1.crt server1.noauthid.crt server1.crt.openssl server1.v1.crt
 
 server2.crt: server2.req.sha256
 	$(MBEDTLS_CERT_WRITE) request_file=server2.req.sha256 serial=2 issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) not_before=20110212144406 not_after=20210212144406 md=SHA1 version=3 output_file=$@
-all_final += server2.crt
+server2.der: server2.crt
+	$(OPENSSL) x509 -inform PEM -in $< -outform DER -out $@
+all_final += server2.crt server2.der
 
 server2-sha256.crt: server2.req.sha256
 	$(MBEDTLS_CERT_WRITE) request_file=server2.req.sha256 serial=2 issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) not_before=20110212144406 not_after=20210212144406 md=SHA256 version=3 output_file=$@

tests/suites/test_suite_x509parse.data

@@ -2,14 +2,26 @@ X509 Certificate information #1
 depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
 x509_cert_info:"data_files/server1.crt":"cert. version     \: 3\nserial number     \: 01\nissuer name       \: C=NL, O=PolarSSL, CN=PolarSSL Test CA\nsubject name      \: C=NL, O=PolarSSL, CN=PolarSSL Server 1\nissued  on        \: 2011-02-12 14\:44\:06\nexpires on        \: 2021-02-12 14\:44\:06\nsigned using      \: RSA with SHA1\nRSA key size      \: 2048 bits\nbasic constraints \: CA=false\n"
 
+X509 Certificate information #1 (DER)
+depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
+x509_cert_info:"data_files/server1.der":"cert. version     \: 3\nserial number     \: 01\nissuer name       \: C=NL, O=PolarSSL, CN=PolarSSL Test CA\nsubject name      \: C=NL, O=PolarSSL, CN=PolarSSL Server 1\nissued  on        \: 2011-02-12 14\:44\:06\nexpires on        \: 2021-02-12 14\:44\:06\nsigned using      \: RSA with SHA1\nRSA key size      \: 2048 bits\nbasic constraints \: CA=false\n"
+
 X509 Certificate information #2
 depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
 x509_cert_info:"data_files/server2.crt":"cert. version     \: 3\nserial number     \: 02\nissuer name       \: C=NL, O=PolarSSL, CN=PolarSSL Test CA\nsubject name      \: C=NL, O=PolarSSL, CN=localhost\nissued  on        \: 2011-02-12 14\:44\:06\nexpires on        \: 2021-02-12 14\:44\:06\nsigned using      \: RSA with SHA1\nRSA key size      \: 2048 bits\nbasic constraints \: CA=false\n"
 
+X509 Certificate information #2 (DER)
+depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
+x509_cert_info:"data_files/server2.der":"cert. version     \: 3\nserial number     \: 02\nissuer name       \: C=NL, O=PolarSSL, CN=PolarSSL Test CA\nsubject name      \: C=NL, O=PolarSSL, CN=localhost\nissued  on        \: 2011-02-12 14\:44\:06\nexpires on        \: 2021-02-12 14\:44\:06\nsigned using      \: RSA with SHA1\nRSA key size      \: 2048 bits\nbasic constraints \: CA=false\n"
+
 X509 Certificate information #3
 depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
 x509_cert_info:"data_files/test-ca.crt":"cert. version     \: 3\nserial number     \: 03\nissuer name       \: C=NL, O=PolarSSL, CN=PolarSSL Test CA\nsubject name      \: C=NL, O=PolarSSL, CN=PolarSSL Test CA\nissued  on        \: 2011-02-12 14\:44\:00\nexpires on        \: 2021-02-12 14\:44\:00\nsigned using      \: RSA with SHA1\nRSA key size      \: 2048 bits\nbasic constraints \: CA=true\n"
 
+X509 Certificate information #3 (DER)
+depends_on:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
+x509_cert_info:"data_files/test-ca.der":"cert. version     \: 3\nserial number     \: 03\nissuer name       \: C=NL, O=PolarSSL, CN=PolarSSL Test CA\nsubject name      \: C=NL, O=PolarSSL, CN=PolarSSL Test CA\nissued  on        \: 2011-02-12 14\:44\:00\nexpires on        \: 2021-02-12 14\:44\:00\nsigned using      \: RSA with SHA1\nRSA key size      \: 2048 bits\nbasic constraints \: CA=true\n"
+
 X509 Certificate information MD2 Digest
 depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_MD2_C
 x509_cert_info:"data_files/cert_md2.crt":"cert. version     \: 3\nserial number     \: 09\nissuer name       \: C=NL, O=PolarSSL, CN=PolarSSL Test CA\nsubject name      \: C=NL, O=PolarSSL, CN=PolarSSL Cert MD2\nissued  on        \: 2009-07-12 10\:56\:59\nexpires on        \: 2011-07-12 10\:56\:59\nsigned using      \: RSA with MD2\nRSA key size      \: 2048 bits\nbasic constraints \: CA=false\n"

tests/suites/test_suite_x509parse.function

@@ -513,8 +513,22 @@ void x509parse_crt( data_t * buf, char * result_str, int result )
     mbedtls_x509_crt_init( &crt );
     memset( output, 0, 2000 );
 
+    TEST_ASSERT( mbedtls_x509_crt_parse_der( &crt, buf->x, buf->len ) == ( result ) );
+    if( ( result ) == 0 )
+    {
+        res = mbedtls_x509_crt_info( (char *) output, 2000, "", &crt );
 
-    TEST_ASSERT( mbedtls_x509_crt_parse( &crt, buf->x, buf->len ) == ( result ) );
+        TEST_ASSERT( res != -1 );
+        TEST_ASSERT( res != -2 );
+
+        TEST_ASSERT( strcmp( (char *) output, result_str ) == 0 );
+    }
+
+    mbedtls_x509_crt_free( &crt );
+    mbedtls_x509_crt_init( &crt );
+    memset( output, 0, 2000 );
+
+    TEST_ASSERT( mbedtls_x509_crt_parse_der_nocopy( &crt, buf->x, buf->len ) == ( result ) );
     if( ( result ) == 0 )
     {
         res = mbedtls_x509_crt_info( (char *) output, 2000, "", &crt );