* New upstream release (closes: #536182). Yes, I know 5.3p1 has been out

  for a while, but there's no GSSAPI patch available for it yet.
  - Change the default cipher order to prefer the AES CTR modes and the
    revised "arcfour256" mode to CBC mode ciphers that are susceptible to
    CPNI-957037 "Plaintext Recovery Attack Against SSH".
  - Add countermeasures to mitigate CPNI-957037-style attacks against the
    SSH protocol's use of CBC-mode ciphers. Upon detection of an invalid
    packet length or Message Authentication Code, ssh/sshd will continue
    reading up to the maximum supported packet length rather than
    immediately terminating the connection. This eliminates most of the
    known differences in behaviour that leaked information about the
    plaintext of injected data which formed the basis of this attack
    (closes: #506115, LP: #379329).
  - ForceCommand directive now accepts commandline arguments for the
    internal-sftp server (closes: #524423, LP: #362511).
  - Add AllowAgentForwarding to available Match keywords list (closes:
    #540623).
  - Make ssh(1) send the correct channel number for
    SSH2_MSG_CHANNEL_SUCCESS and SSH2_MSG_CHANNEL_FAILURE messages to
    avoid triggering 'Non-public channel' error messages on sshd(8) in
    openssh-5.1.
  - Avoid printing 'Non-public channel' warnings in sshd(8), since the
    ssh(1) has sent incorrect channel numbers since ~2004 (this reverts a
    behaviour introduced in openssh-5.1; closes: #496017).
* Update to GSSAPI patch from
  http://www.sxw.org.uk/computing/patches/openssh-5.2p1-gsskex-all-20090726.patch,
  including cascading credentials support (LP: #416958).

1 files changed, 21 insertions, 4 deletions

diff --git a/kexgsss.c b/kexgsss.c
index 3ca23bbb2..0c3eeaa63 100644
--- a/kexgsss.c
+++ b/kexgsss.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001-2006 Simon Wilkinson. All rights reserved.
+ * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -42,6 +42,9 @@
 #include "dh.h"
 #include "ssh-gss.h"
 #include "monitor_wrap.h"
+#include "servconf.h"
+
+extern ServerOptions options;
 
 void
 kexgss_server(Kex *kex)
@@ -67,6 +70,7 @@ kexgss_server(Kex *kex)
         BIGNUM *dh_client_pub = NULL;
         int type = 0;
         gss_OID oid;
+        char *mechs;
 
         /* Initialise GSSAPI */
 
@@ -75,7 +79,8 @@ kexgss_server(Kex *kex)
          * into life
          */
         if (!ssh_gssapi_oid_table_ok()) 
-                ssh_gssapi_server_mechanisms();
+                if ((mechs = ssh_gssapi_server_mechanisms()))
+                        xfree(mechs);
 
         debug2("%s: Identifying %s", __func__, kex->name);
         oid = ssh_gssapi_id_kex(NULL, kex->name, kex->kex_type);
@@ -191,9 +196,16 @@ kexgss_server(Kex *kex)
         klen = DH_size(dh);
         kbuf = xmalloc(klen); 
         kout = DH_compute_key(kbuf, dh_client_pub, dh);
+        if (kout < 0)
+                fatal("DH_compute_key: failed");
 
         shared_secret = BN_new();
-        BN_bin2bn(kbuf, kout, shared_secret);
+        if (shared_secret == NULL)
+                fatal("kexgss_server: BN_new failed");
+
+        if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
+                fatal("kexgss_server: BN_bin2bn failed");
+
         memset(kbuf, 0, klen);
         xfree(kbuf);
 
@@ -228,7 +240,7 @@ kexgss_server(Kex *kex)
                 fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
         }
 
-        BN_free(dh_client_pub);
+        BN_clear_free(dh_client_pub);
 
         if (kex->session_id == NULL) {
                 kex->session_id_len = hashlen;
@@ -267,5 +279,10 @@ kexgss_server(Kex *kex)
         kex_derive_keys(kex, hash, hashlen, shared_secret);
         BN_clear_free(shared_secret);
         kex_finish(kex);
+
+        /* If this was a rekey, then save out any delegated credentials we
+         * just exchanged.  */
+        if (options.gss_store_rekey)
+                ssh_gssapi_rekey_creds();
 }
 #endif /* GSSAPI */