pkcs7: add support for signed data

OpenSSL provides APIs to generate only the signted data
format PKCS7 i.e. without content type OID. This patch
adds support to parse the data correctly even if formatted
only as signed data

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>

include/mbedtls/pkcs7.h

@@ -96,6 +96,20 @@ typedef mbedtls_asn1_named_data mbedtls_pkcs7_name;
  */
 typedef mbedtls_asn1_sequence mbedtls_pkcs7_sequence;
 
+/**
+ * PKCS7 types
+ */
+typedef enum {
+    MBEDTLS_PKCS7_NONE=0,
+    MBEDTLS_PKCS7_DATA,
+    MBEDTLS_PKCS7_SIGNED_DATA,
+    MBEDTLS_PKCS7_ENVELOPED_DATA,
+    MBEDTLS_PKCS7_SIGNED_AND_ENVELOPED_DATA,
+    MBEDTLS_PKCS7_DIGESTED_DATA,
+    MBEDTLS_PKCS7_ENCRYPTED_DATA,
+}
+mbedtls_pkcs7_type;
+
 /**
  * Structure holding PKCS7 signer info
  */
@@ -168,7 +182,7 @@ void mbedtls_pkcs7_init( mbedtls_pkcs7 *pkcs7 );
  *                 \p buf. In particular, \p buf may be destroyed or reused
  *                 after this call returns.
  *
- * \return         \c 0, if successful.
+ * \return         The \c mbedtls_pkcs7_type of \p buf, if successful.
  * \return         A negative error code on failure.
  */
 int mbedtls_pkcs7_parse_der( mbedtls_pkcs7 *pkcs7, const unsigned char *buf,

library/pkcs7.c

@@ -103,6 +103,7 @@ static int pkcs7_get_content_info_type( unsigned char **p, unsigned char *end,
 {
     size_t len = 0;
     int ret;
+    unsigned char *start = *p;
 
     ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_CONSTRUCTED
                                             | MBEDTLS_ASN1_SEQUENCE );
@@ -110,8 +111,10 @@ static int pkcs7_get_content_info_type( unsigned char **p, unsigned char *end,
         return( MBEDTLS_ERR_PKCS7_INVALID_CONTENT_INFO + ret );
 
     ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_OID );
-    if( ret != 0 )
+    if( ret != 0 ) {
+        *p = start;
         return( MBEDTLS_ERR_PKCS7_INVALID_CONTENT_INFO + ret );
+    }
 
     pkcs7->tag = MBEDTLS_ASN1_OID;
     pkcs7->len = len;
@@ -428,6 +431,7 @@ int mbedtls_pkcs7_parse_der( mbedtls_pkcs7 *pkcs7, const unsigned char *buf,
     unsigned char *end;
     size_t len = 0;
     int ret;
+    int isoidset = 0;
 
     if( !pkcs7 )
         return( MBEDTLS_ERR_PKCS7_BAD_INPUT_DATA );
@@ -444,7 +448,10 @@ int mbedtls_pkcs7_parse_der( mbedtls_pkcs7 *pkcs7, const unsigned char *buf,
 
     ret = pkcs7_get_content_info_type( &start, end, &pkcs7->content_type_oid );
     if( ret != 0 )
-        goto out;
+    {
+        len = buflen;
+        goto try_data;
+    }
 
     if( ! MBEDTLS_OID_CMP( MBEDTLS_OID_PKCS7_DATA, &pkcs7->content_type_oid )
      || ! MBEDTLS_OID_CMP( MBEDTLS_OID_PKCS7_ENCRYPTED_DATA, &pkcs7->content_type_oid )
@@ -463,17 +470,31 @@ int mbedtls_pkcs7_parse_der( mbedtls_pkcs7 *pkcs7, const unsigned char *buf,
         goto out;
     }
 
+    isoidset = 1;
     start = start + pkcs7->content_type_oid.len;
 
     ret = pkcs7_get_next_content_len( &start, end, &len );
     if( ret != 0 )
         goto out;
 
+try_data:
     ret = pkcs7_get_signed_data( start, len, &pkcs7->signed_data );
+    if ( ret != 0 )
+        goto out;
+
+    if ( !isoidset )
+    {
+        pkcs7->content_type_oid.tag = MBEDTLS_ASN1_OID;
+        pkcs7->content_type_oid.len = MBEDTLS_OID_SIZE( MBEDTLS_OID_PKCS7_SIGNED_DATA );
+        pkcs7->content_type_oid.p = (unsigned char *)MBEDTLS_OID_PKCS7_SIGNED_DATA;
+    }
+
+    ret = MBEDTLS_PKCS7_SIGNED_DATA;
 
 out:
-    if ( ret != 0 )
+    if ( ret < 0 )
         mbedtls_pkcs7_free( pkcs7 );
+
     return( ret );
 }
 

tests/data_files/Makefile

@@ -1223,6 +1223,11 @@ pkcs7_signerInfo_serial_invalid_size.der: pkcs7_data_cert_signed_sha256.der
 	echo -en '\x15' | dd of=$@ seek=973 bs=1 conv=notrunc
 all_final += pkcs7_signerInfo_serial_invalid_size.der
 
+# pkcs7 signature file just with signed data
+pkcs7_data_cert_signeddata_sha256.der: pkcs7_data_cert_signed_sha256.der
+	dd if=pkcs7_data_cert_signed_sha256.der of=$@ skip=19 bs=1
+all_final += pkcs7_data_cert_signeddata_sha256.der
+
 ################################################################
 #### Diffie-Hellman parameters
 ################################################################

tests/suites/test_suite_pkcs7.data

@@ -51,3 +51,6 @@ pkcs7_parse_failure:"data_files/pkcs7_signerInfo_issuer_invalid_size.der"
 
 PKCS7 Signed Data Parse Failure Corrupt signerInfo.serial #15.2
 pkcs7_parse_failure:"data_files/pkcs7_signerInfo_serial_invalid_size.der"
+
+PKCS7 Only Signed Data Parse Pass #15
+pkcs7_parse:"data_files/pkcs7_data_cert_signeddata_sha256.der"

tests/suites/test_suite_pkcs7.function

@@ -29,7 +29,7 @@ void pkcs7_parse( char *pkcs7_file )
     TEST_ASSERT( res == 0 );
 
     res = mbedtls_pkcs7_parse_der( &pkcs7, pkcs7_buf, buflen );
-    TEST_ASSERT( res == 0 );
+    TEST_ASSERT( res == MBEDTLS_PKCS7_SIGNED_DATA );
 
 exit:
     mbedtls_free( pkcs7_buf );
@@ -52,7 +52,7 @@ void pkcs7_parse_without_cert( char *pkcs7_file )
     TEST_ASSERT( res == 0 );
 
     res = mbedtls_pkcs7_parse_der( &pkcs7, pkcs7_buf, buflen );
-    TEST_ASSERT( res == 0 );
+    TEST_ASSERT( res == MBEDTLS_PKCS7_SIGNED_DATA );
 
 exit:
     mbedtls_free( pkcs7_buf );
@@ -210,10 +210,10 @@ void pkcs7_verify( char *pkcs7_file, char *crt, char *filetobesigned )
     TEST_ASSERT( res == 0 );
 
     res = mbedtls_pkcs7_parse_der( &pkcs7, pkcs7_buf, buflen );
-    TEST_ASSERT( res == 0 );
+    TEST_ASSERT( res == MBEDTLS_PKCS7_SIGNED_DATA );
     mbedtls_free( pkcs7_buf );
 
-    res = stat(filetobesigned, &st);
+    res = stat( filetobesigned, &st );
     TEST_ASSERT( res == 0 );
 
     file = fopen( filetobesigned, "rb" );
@@ -263,9 +263,9 @@ void pkcs7_verify_hash( char *pkcs7_file, char *crt, char *filetobesigned )
     TEST_ASSERT( res == 0 );
 
     res = mbedtls_pkcs7_parse_der( &pkcs7, pkcs7_buf, buflen );
-    TEST_ASSERT( res == 0 );
+    TEST_ASSERT( res == MBEDTLS_PKCS7_SIGNED_DATA );
 
-    res = stat(filetobesigned, &st);
+    res = stat( filetobesigned, &st );
     TEST_ASSERT( res == 0 );
 
     file = fopen( filetobesigned, "rb" );
@@ -319,12 +319,12 @@ void pkcs7_verify_badcert( char *pkcs7_file, char *crt, char *filetobesigned )
     TEST_ASSERT( res == 0 );
 
     res = mbedtls_pkcs7_parse_der( &pkcs7, pkcs7_buf, buflen );
-    TEST_ASSERT( res == 0 );
+    TEST_ASSERT( res == MBEDTLS_PKCS7_SIGNED_DATA );
 
     res = mbedtls_x509_crt_parse_file( &x509, crt );
     TEST_ASSERT( res == 0 );
 
-    res = stat(filetobesigned, &st);
+    res = stat( filetobesigned, &st );
     TEST_ASSERT( res == 0 );
 
     file = fopen( filetobesigned, "rb" );
@@ -369,12 +369,12 @@ void pkcs7_verify_tampered_data( char *pkcs7_file, char *crt, char *filetobesign
     TEST_ASSERT( res == 0 );
 
     res = mbedtls_pkcs7_parse_der( &pkcs7, pkcs7_buf, buflen );
-    TEST_ASSERT( res == 0 );
+    TEST_ASSERT( res == MBEDTLS_PKCS7_SIGNED_DATA );
 
     res = mbedtls_x509_crt_parse_file( &x509, crt );
     TEST_ASSERT( res == 0 );
 
-    res = stat(filetobesigned, &st);
+    res = stat( filetobesigned, &st );
     TEST_ASSERT( res == 0 );
 
     file = fopen( filetobesigned, "rb" );