chiark / gitweb /
integer and buffer overflows: introduce a number of asserts
[secnet.git] / dh.c
diff --git a/dh.c b/dh.c
index 67ebd5068bbff17d5ccabd885fd0c10931492c49..fff9b998c54062eaa473968640f40acc6b6f8a5d 100644 (file)
--- a/dh.c
+++ b/dh.c
@@ -1,38 +1,6 @@
-/***************************************************************************
- *
- *              Part II Project, "A secure, private IP network"
- *              Stephen Early <sde1000@cam.ac.uk>
- *   
- *
- *     $RCSfile: dh.c,v $
- *
- *  Description: Diffie-Hellman implementation
- *
- *    Copyright: (C) Stephen Early 1995
- *
- *    $Revision: 1.3 $
- *
- *        $Date: 1996/05/16 18:38:54 $
- *
- *       $State: Exp $
- *
- ***************************************************************************/
-
-/*
- * $Log: dh.c,v $
- * Revision 1.3  1996/05/16 18:38:54  sde1000
- * Removed unused hexdigits variable.
- *
- * Revision 1.2  1996/04/14 16:33:52  sde1000
- * Moved mpbin/mpstring functions into util.c
- *
- * Revision 1.1  1996/04/14 16:21:47  sde1000
- * Initial revision
- *
- */
-
 #include <stdio.h>
 #include <gmp.h>
+#include <limits.h>
 
 #include "secnet.h"
 #include "util.h"
@@ -64,8 +32,9 @@ static string_t dh_makepublic(void *sst, uint8_t *secret, uint32_t secretlen)
     return r;
 }
 
+static dh_makeshared_fn dh_makeshared;
 static void dh_makeshared(void *sst, uint8_t *secret, uint32_t secretlen,
-                         string_t rempublic, uint8_t *sharedsecret,
+                         cstring_t rempublic, uint8_t *sharedsecret,
                          uint32_t buflen)
 {
     struct dh *st=sst;
@@ -145,12 +114,20 @@ static list_t *dh_apply(closure_t *self, struct cloc loc, dict_t *context,
            cfgfatal(loc,"diffie-hellman","modulus must be a prime\n");
        }
     }
-    st->ops.len=mpz_sizeinbase(&st->p,2)/8;
+
+    size_t sz=mpz_sizeinbase(&st->p,2)/8;
+    if (sz>INT_MAX) {
+       cfgfatal(loc,"diffie-hellman","modulus far too large\n");
+    }
+    if (mpz_cmp(&st->g,&st->p) >= 0) {
+       cfgfatal(loc,"diffie-hellman","generator must be less than modulus\n");
+    }
+
+    st->ops.len=sz;
 
     return new_closure(&st->cl);
 }
 
-init_module dh_module;
 void dh_module(dict_t *dict)
 {
     add_closure(dict,"diffie-hellman",dh_apply);