[PATCH] Fix encryption/decryption return type for GOST28147

[Jussi Kivilinna]

* cipher/gost.h (_gcry_gost_enc_one): Change return type to
'unsigned int'.
* cipher/gost28147.c (max): New macro.
(gost_encrypt_block, gost_decrypt_block): Return burn stack depth.
(_gcry_gost_enc_one): Return burn stack depth from gost_encrypt_block.
--

Return type for block cipher functions was lately changed from 'void' to
'unsigned int' to pass burn stack depth to cipher mode code. Patch fixes
gost28147 to return stack burn value.

Signed-off-by: Jussi Kivilinna <jussi.kivilinna at iki.fi>
---
 cipher/gost.h      |    2 +-
 cipher/gost28147.c |   23 +++++++++++++++++++----
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/cipher/gost.h b/cipher/gost.h
index e1cf033..42021aa 100644
--- a/cipher/gost.h
+++ b/cipher/gost.h
@@ -27,7 +27,7 @@ typedef struct {
 } GOST28147_context;
 
 /* This is a simple interface that will be used by GOST R 34.11-94 */
-extern void _gcry_gost_enc_one (GOST28147_context *c, const byte *key,
+extern unsigned int _gcry_gost_enc_one (GOST28147_context *c, const byte *key,
     byte *out, byte *in);
 
 #endif
diff --git a/cipher/gost28147.c b/cipher/gost28147.c
index 5d6d1e7..862e7d6 100644
--- a/cipher/gost28147.c
+++ b/cipher/gost28147.c
@@ -35,6 +35,9 @@
 #include "cipher.h"
 
 
+#define max(a, b) (((a) > (b)) ? (a) : (b))
+
+
 /* This is an s-box from RFC4357, named GostR3411-94-TestParamSet
  * For now it is the only s-box supported, as libgcrypt lacks mechanism
  * for passing parameters to cipher in a usefull way. */
@@ -107,7 +110,7 @@ gost_val (GOST28147_context *ctx, u32 cm1, int subkey)
   return (cm1 << 11) | (cm1 >> 21);
 }
 
-static void
+static unsigned int
 gost_encrypt_block (void *c, byte *outbuf, const byte *inbuf)
 {
   GOST28147_context *ctx = c;
@@ -153,16 +156,22 @@ gost_encrypt_block (void *c, byte *outbuf, const byte *inbuf)
   outbuf[1 + 4] = (n1 >> (1 * 8)) & 0xff;
   outbuf[2 + 4] = (n1 >> (2 * 8)) & 0xff;
   outbuf[3 + 4] = (n1 >> (3 * 8)) & 0xff;
+
+  return /* burn_stack */ 4*sizeof(void*) /* func call */ +
+                          3*sizeof(void*) /* stack */ +
+                          max( 4*sizeof(void*) /* gost_val call */,
+                               3*sizeof(void*) /* gost_set_subst call */ +
+                               2*sizeof(void*) /* gost_set subst stack*/ );
 }
 
-void _gcry_gost_enc_one (GOST28147_context *c, const byte *key,
+unsigned int _gcry_gost_enc_one (GOST28147_context *c, const byte *key,
     byte *out, byte *in)
 {
   gost_setkey (c, key, 32);
-  gost_encrypt_block (c, out, in);
+  return gost_encrypt_block (c, out, in);
 }
 
-static void
+static unsigned int
 gost_decrypt_block (void *c, byte *outbuf, const byte *inbuf)
 {
   GOST28147_context *ctx = c;
@@ -208,6 +217,12 @@ gost_decrypt_block (void *c, byte *outbuf, const byte *inbuf)
   outbuf[1 + 4] = (n1 >> (1 * 8)) & 0xff;
   outbuf[2 + 4] = (n1 >> (2 * 8)) & 0xff;
   outbuf[3 + 4] = (n1 >> (3 * 8)) & 0xff;
+
+  return /* burn_stack */ 4*sizeof(void*) /* func call */ +
+                          3*sizeof(void*) /* stack */ +
+                          max( 4*sizeof(void*) /* gost_val call */,
+                               3*sizeof(void*) /* gost_set_subst call */ +
+                               2*sizeof(void*) /* gost_set subst stack*/ );
 }
 
 gcry_cipher_spec_t _gcry_cipher_spec_gost28147 =