- djm@cvs.openbsd.org 2009/01/01 21:17:36

     [kexgexs.c]
     fix hash calculation for KEXGEX: hash over the original client-supplied
     values and not the sanity checked versions that we acutally use;
     bz#1540 reported by john.smith AT arrows.demon.co.uk
     ok markus@

diff --git a/ChangeLog b/ChangeLog
index dea2f6015c9c5e7b8c1db4d8e268f4a17bd9c866..abeb17d279352b5e9e7844f6b5e2832f63c9fe10 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -36,6 +36,12 @@
      call channel destroy callbacks on receipt of open failure messages.
      fixes client hangs when connecting to a server that has MaxSessions=0
      set spotted by imorgan AT nas.nasa.gov; ok markus@
+   - djm@cvs.openbsd.org 2009/01/01 21:17:36
+     [kexgexs.c]
+     fix hash calculation for KEXGEX: hash over the original client-supplied
+     values and not the sanity checked versions that we acutally use;
+     bz#1540 reported by john.smith AT arrows.demon.co.uk
+     ok markus@
 
 20090107
  - (djm) [uidswap.c] bz#1412: Support >16 supplemental groups in OS X.

diff --git a/kexgexs.c b/kexgexs.c
index a037f57f2814e2cc783239e42cea0aca1a114b58..76a0f8ca7164d5e0259a49e90e6b29e061ec7381 100644 (file)
--- a/kexgexs.c
+++ b/kexgexs.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: kexgexs.c,v 1.10 2006/11/06 21:25:28 markus Exp $ */
+/* $OpenBSD: kexgexs.c,v 1.11 2009/01/01 21:17:36 djm Exp $ */
 /*
  * Copyright (c) 2000 Niels Provos.  All rights reserved.
  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
@@ -56,7 +56,8 @@ kexgex_server(Kex *kex)
        DH *dh;
        u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
        u_int sbloblen, klen, slen, hashlen;
-       int min = -1, max = -1, nbits = -1, type, kout;
+       int omin = -1, min = -1, omax = -1, max = -1, onbits = -1, nbits = -1;
+       int type, kout;
 
        if (kex->load_host_key == NULL)
                fatal("Cannot load hostkey");
@@ -68,27 +69,29 @@ kexgex_server(Kex *kex)
        switch (type) {
        case SSH2_MSG_KEX_DH_GEX_REQUEST:
                debug("SSH2_MSG_KEX_DH_GEX_REQUEST received");
-               min = packet_get_int();
-               nbits = packet_get_int();
-               max = packet_get_int();
+               omin = min = packet_get_int();
+               onbits = nbits = packet_get_int();
+               omax = max = packet_get_int();
                min = MAX(DH_GRP_MIN, min);
                max = MIN(DH_GRP_MAX, max);
+               nbits = MAX(DH_GRP_MIN, nbits);
+               nbits = MIN(DH_GRP_MAX, nbits);
                break;
        case SSH2_MSG_KEX_DH_GEX_REQUEST_OLD:
                debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD received");
-               nbits = packet_get_int();
-               min = DH_GRP_MIN;
-               max = DH_GRP_MAX;
+               onbits = nbits = packet_get_int();
                /* unused for old GEX */
+               omin = min = DH_GRP_MIN;
+               omax = max = DH_GRP_MAX;
                break;
        default:
                fatal("protocol error during kex, no DH_GEX_REQUEST: %d", type);
        }
        packet_check_eom();
 
-       if (max < min || nbits < min || max < nbits)
+       if (omax < omin || onbits < omin || omax < onbits)
                fatal("DH_GEX_REQUEST, bad parameters: %d !< %d !< %d",
-                   min, nbits, max);
+                   omin, onbits, omax);
 
        /* Contact privileged parent */
        dh = PRIVSEP(choose_dh(min, nbits, max));
@@ -149,7 +152,7 @@ kexgex_server(Kex *kex)
        key_to_blob(server_host_key, &server_host_key_blob, &sbloblen);
 
        if (type == SSH2_MSG_KEX_DH_GEX_REQUEST_OLD)
-               min = max = -1;
+               omin = min = omax = max = -1;
 
        /* calc H */
        kexgex_hash(
@@ -159,7 +162,7 @@ kexgex_server(Kex *kex)
            buffer_ptr(&kex->peer), buffer_len(&kex->peer),
            buffer_ptr(&kex->my), buffer_len(&kex->my),
            server_host_key_blob, sbloblen,
-           min, nbits, max,
+           omin, onbits, omax,
            dh->p, dh->g,
            dh_client_pub,
            dh->pub_key,