* New upstream release (http://www.openssh.org/txt/release-5.7):

  - Implement Elliptic Curve Cryptography modes for key exchange (ECDH)
    and host/user keys (ECDSA) as specified by RFC5656.  ECDH and ECDSA
    offer better performance than plain DH and DSA at the same equivalent
    symmetric key length, as well as much shorter keys.
  - sftp(1)/sftp-server(8): add a protocol extension to support a hard
    link operation.  It is available through the "ln" command in the
    client.  The old "ln" behaviour of creating a symlink is available
    using its "-s" option or through the preexisting "symlink" command.
  - scp(1): Add a new -3 option to scp: Copies between two remote hosts
    are transferred through the local host (closes: #508613).
  - ssh(1): "atomically" create the listening mux socket by binding it on
    a temporary name and then linking it into position after listen() has
    succeeded.  This allows the mux clients to determine that the server
    socket is either ready or stale without races (closes: #454784).
    Stale server sockets are now automatically removed (closes: #523250).
  - ssh(1): install a SIGCHLD handler to reap expired child process
    (closes: #594687).
  - ssh(1)/ssh-agent(1): honour $TMPDIR for client xauth and ssh-agent
    temporary directories (closes: #357469, although only if you arrange
    for ssh-agent to actually see $TMPDIR since the setgid bit will cause
    it to be stripped off).

1 files changed, 32 insertions, 6 deletions

diff --git a/schnorr.c b/schnorr.c
index c17ff3241..4d54d6881 100644
--- a/schnorr.c
+++ b/schnorr.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: schnorr.c,v 1.3 2009/03/05 07:18:19 djm Exp $ */
+/* $OpenBSD: schnorr.c,v 1.5 2010/12/03 23:49:26 djm Exp $ */
 /*
  * Copyright (c) 2008 Damien Miller.  All rights reserved.
  *
@@ -138,6 +138,10 @@ schnorr_sign(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g,
                 error("%s: g_x < 1", __func__);
                 return -1;
         }
+        if (BN_cmp(g_x, grp_p) >= 0) {
+                error("%s: g_x > g", __func__);
+                return -1;
+        }
 
         h = g_v = r = tmp = v = NULL;
         if ((bn_ctx = BN_CTX_new()) == NULL) {
@@ -254,14 +258,19 @@ schnorr_verify(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g,
     const BIGNUM *r, const BIGNUM *e)
 {
         int success = -1;
-        BIGNUM *h, *g_xh, *g_r, *expected;
+        BIGNUM *h = NULL, *g_xh = NULL, *g_r = NULL, *gx_q = NULL;
+        BIGNUM *expected = NULL;
         BN_CTX *bn_ctx;
 
         SCHNORR_DEBUG_BN((g_x, "%s: g_x = ", __func__));
 
         /* Avoid degenerate cases: g^0 yields a spoofable signature */
         if (BN_cmp(g_x, BN_value_one()) <= 0) {
-                error("%s: g_x < 1", __func__);
+                error("%s: g_x <= 1", __func__);
+                return -1;
+        }
+        if (BN_cmp(g_x, grp_p) >= 0) {
+                error("%s: g_x >= p", __func__);
                 return -1;
         }
 
@@ -272,6 +281,7 @@ schnorr_verify(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g,
         }
         if ((g_xh = BN_new()) == NULL ||
             (g_r = BN_new()) == NULL ||
+            (gx_q = BN_new()) == NULL ||
             (expected = BN_new()) == NULL) {
                 error("%s: BN_new", __func__);
                 goto out;
@@ -280,6 +290,17 @@ schnorr_verify(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g,
         SCHNORR_DEBUG_BN((e, "%s: e = ", __func__));
         SCHNORR_DEBUG_BN((r, "%s: r = ", __func__));
 
+        /* gx_q = (g^x)^q must === 1 mod p */
+        if (BN_mod_exp(gx_q, g_x, grp_q, grp_p, bn_ctx) == -1) {
+                error("%s: BN_mod_exp (g_x^q mod p)", __func__);
+                goto out;
+        }
+        if (BN_cmp(gx_q, BN_value_one()) != 0) {
+                error("%s: Invalid signature (g^x)^q != 1 mod p", __func__);
+                goto out;
+        }
+
+        SCHNORR_DEBUG_BN((g_xh, "%s: g_xh = ", __func__));
         /* h = H(g || g^v || g^x || id) */
         if ((h = schnorr_hash(grp_p, grp_q, grp_g, evp_md, e, g_x,
             id, idlen)) == NULL) {
@@ -314,9 +335,14 @@ schnorr_verify(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g,
         BN_CTX_free(bn_ctx);
         if (h != NULL)
                 BN_clear_free(h);
-        BN_clear_free(g_xh);
-        BN_clear_free(g_r);
-        BN_clear_free(expected);
+        if (gx_q != NULL)
+                BN_clear_free(gx_q);
+        if (g_xh != NULL)
+                BN_clear_free(g_xh);
+        if (g_r != NULL)
+                BN_clear_free(g_r);
+        if (expected != NULL)
+                BN_clear_free(expected);
         return success;
 }