Rename and reorder function parameters

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>

library/constant_time.c

@@ -310,19 +310,19 @@ void mbedtls_cf_memcpy_if_eq( unsigned char *dest,
         dest[i] = ( src[i] & mask ) | ( dest[i] & ~mask );
 }
 
-void mbedtls_cf_memcpy_offset( unsigned char *dst,
+void mbedtls_cf_memcpy_offset( unsigned char *dest,
-                               const unsigned char *src_base,
+                               const unsigned char *src,
-                               size_t offset_secret,
+                               size_t offset,
                                size_t offset_min,
                                size_t offset_max,
                                size_t len )
 {
-    size_t offset;
+    size_t offsetval;
 
-    for( offset = offset_min; offset <= offset_max; offset++ )
+    for( offsetval = offset_min; offsetval <= offset_max; offsetval++ )
     {
-        mbedtls_cf_memcpy_if_eq( dst, src_base + offset, len,
+        mbedtls_cf_memcpy_if_eq( dest, src + offsetval, len,
-                                 offset, offset_secret );
+                                 offsetval, offset );
     }
 }
 
@@ -564,11 +564,11 @@ int mbedtls_mpi_lt_mpi_ct( const mbedtls_mpi *X,
 #if defined(MBEDTLS_PKCS1_V15) && defined(MBEDTLS_RSA_C) && !defined(MBEDTLS_RSA_ALT)
 
 int mbedtls_cf_rsaes_pkcs1_v15_unpadding( int mode,
+                                          unsigned char *input,
                                           size_t ilen,
-                                          size_t *olen,
                                           unsigned char *output,
                                           size_t output_max_len,
-                                          unsigned char *buf )
+                                          size_t *olen )
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     size_t i, plaintext_max_size;
@@ -594,19 +594,19 @@ int mbedtls_cf_rsaes_pkcs1_v15_unpadding( int mode,
 
     /* Check and get padding length in constant time and constant
      * memory trace. The first byte must be 0. */
-    bad |= buf[0];
+    bad |= input[0];
 
     if( mode == MBEDTLS_RSA_PRIVATE )
     {
         /* Decode EME-PKCS1-v1_5 padding: 0x00 || 0x02 || PS || 0x00
          * where PS must be at least 8 nonzero bytes. */
-        bad |= buf[1] ^ MBEDTLS_RSA_CRYPT;
+        bad |= input[1] ^ MBEDTLS_RSA_CRYPT;
 
         /* Read the whole buffer. Set pad_done to nonzero if we find
          * the 0x00 byte and remember the padding length in pad_count. */
         for( i = 2; i < ilen; i++ )
         {
-            pad_done  |= ((buf[i] | (unsigned char)-buf[i]) >> 7) ^ 1;
+            pad_done  |= ((input[i] | (unsigned char)-input[i]) >> 7) ^ 1;
             pad_count += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1;
         }
     }
@@ -614,16 +614,16 @@ int mbedtls_cf_rsaes_pkcs1_v15_unpadding( int mode,
     {
         /* Decode EMSA-PKCS1-v1_5 padding: 0x00 || 0x01 || PS || 0x00
          * where PS must be at least 8 bytes with the value 0xFF. */
-        bad |= buf[1] ^ MBEDTLS_RSA_SIGN;
+        bad |= input[1] ^ MBEDTLS_RSA_SIGN;
 
         /* Read the whole buffer. Set pad_done to nonzero if we find
          * the 0x00 byte and remember the padding length in pad_count.
          * If there's a non-0xff byte in the padding, the padding is bad. */
         for( i = 2; i < ilen; i++ )
         {
-            pad_done |= mbedtls_cf_uint_if( buf[i], 0, 1 );
+            pad_done |= mbedtls_cf_uint_if( input[i], 0, 1 );
             pad_count += mbedtls_cf_uint_if( pad_done, 0, 1 );
-            bad |= mbedtls_cf_uint_if( pad_done, 0, buf[i] ^ 0xFF );
+            bad |= mbedtls_cf_uint_if( pad_done, 0, input[i] ^ 0xFF );
         }
     }
 
@@ -668,7 +668,7 @@ int mbedtls_cf_rsaes_pkcs1_v15_unpadding( int mode,
      * through memory or cache access patterns. */
     bad = mbedtls_cf_uint_mask( bad | output_too_large );
     for( i = 11; i < ilen; i++ )
-        buf[i] &= ~bad;
+        input[i] &= ~bad;
 
     /* If the plaintext is too large, truncate it to the buffer size.
      * Copy anyway to avoid revealing the length through timing, because
@@ -684,7 +684,7 @@ int mbedtls_cf_rsaes_pkcs1_v15_unpadding( int mode,
      * does not depend on the plaintext size. After this move, the
      * starting location of the plaintext is no longer sensitive
      * information. */
-    mbedtls_cf_mem_move_to_left( buf + ilen - plaintext_max_size,
+    mbedtls_cf_mem_move_to_left( input + ilen - plaintext_max_size,
                                  plaintext_max_size,
                                  plaintext_max_size - plaintext_size );
 
@@ -696,7 +696,7 @@ int mbedtls_cf_rsaes_pkcs1_v15_unpadding( int mode,
      * length, validity of padding, success of the decryption, and other
      * secrets. */
     if( output_max_len != 0 )
-        memcpy( output, buf + ilen - plaintext_max_size, plaintext_max_size );
+        memcpy( output, input + ilen - plaintext_max_size, plaintext_max_size );
 
     /* Report the amount of data we copied to the output buffer. In case
      * of errors (bad padding or output too large), the value of *olen

library/constant_time.h

@@ -263,21 +263,21 @@ void mbedtls_cf_memcpy_if_eq( unsigned char *dest,
  * offset_secret, but only on \p offset_min, \p offset_max and \p len.
  * Functionally equivalent to memcpy(dst, src + offset_secret, len).
  *
- * \param dst           The destination buffer. This must point to a writable
+ * \param dest          The destination buffer. This must point to a writable
  *                      buffer of at least \p len bytes.
- * \param src_base      The base of the source buffer. This must point to a
+ * \param src           The base of the source buffer. This must point to a
  *                      readable buffer of at least \p offset_max + \p len
- *                      bytes.
+ *                      bytes. Shouldn't overlap with \p dest.
- * \param offset_secret The offset in the source buffer from which to copy.
+ * \param offset        The offset in the source buffer from which to copy.
  *                      This must be no less than \p offset_min and no greater
  *                      than \p offset_max.
- * \param offset_min    The minimal value of \p offset_secret.
+ * \param offset_min    The minimal value of \p offset.
- * \param offset_max    The maximal value of \p offset_secret.
+ * \param offset_max    The maximal value of \p offset.
  * \param len           The number of bytes to copy.
  */
-void mbedtls_cf_memcpy_offset( unsigned char *dst,
+void mbedtls_cf_memcpy_offset( unsigned char *dest,
-                               const unsigned char *src_base,
+                               const unsigned char *src,
-                               size_t offset_secret,
+                               size_t offset,
                                size_t offset_min,
                                size_t offset_max,
                                size_t len );
@@ -342,22 +342,22 @@ int mbedtls_cf_hmac( mbedtls_md_context_t *ctx,
  *
  * \param mode           The mode of operation. This must be either
  *                       #MBEDTLS_RSA_PRIVATE or #MBEDTLS_RSA_PUBLIC (deprecated).
+ * \param input          The input buffer for the unpadding operation.
  * \param ilen           The length of the ciphertext.
- * \param olen           The address at which to store the length of
- *                       the plaintext. This must not be \c NULL.
  * \param output         The buffer used to hold the plaintext. This must
  *                       be a writable buffer of length \p output_max_len Bytes.
  * \param output_max_len The length in Bytes of the output buffer \p output.
- * \param buf            The input buffer for the unpadding operation.
+ * \param olen           The address at which to store the length of
+ *                       the plaintext. This must not be \c NULL.
  *
  * \return         \c 0 on success.
  * \return         An \c MBEDTLS_ERR_RSA_XXX error code on failure.
  */
 int mbedtls_cf_rsaes_pkcs1_v15_unpadding( int mode,
+                                          unsigned char *input,
                                           size_t ilen,
-                                          size_t *olen,
                                           unsigned char *output,
                                           size_t output_max_len,
-                                          unsigned char *buf );
+                                          size_t *olen );
 
 #endif /* MBEDTLS_PKCS1_V15 && MBEDTLS_RSA_C && ! MBEDTLS_RSA_ALT */

library/rsa.c

@@ -1517,9 +1517,8 @@ int mbedtls_rsa_rsaes_pkcs1_v15_decrypt( mbedtls_rsa_context *ctx,
     if( ret != 0 )
         goto cleanup;
 
-    ret = mbedtls_cf_rsaes_pkcs1_v15_unpadding( mode, ilen, olen, output,
+    ret = mbedtls_cf_rsaes_pkcs1_v15_unpadding( mode, buf, ilen,
-                                                output_max_len,
+                                                output, output_max_len, olen );
-                                                (unsigned char *) &buf );
 
 cleanup:
     mbedtls_platform_zeroize( buf, sizeof( buf ) );