1 files changed, 73 insertions, 23 deletions

diff --git a/kexgsss.c b/kexgsss.c
index 80c133ac9..268eeccae 100644
--- a/kexgsss.c
+++ b/kexgsss.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001-2004 Simon Wilkinson. All rights reserved.
+ * Copyright (c) 2001-2005 Simon Wilkinson. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -53,21 +53,31 @@ kexgss_server(Kex *kex)
          */
 
         OM_uint32 ret_flags = 0;
-        gss_buffer_desc gssbuf, send_tok, recv_tok, msg_tok;
+        gss_buffer_desc gssbuf, recv_tok, msg_tok;
+        gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
         Gssctxt *ctxt = NULL;
         unsigned int klen, kout;
         unsigned char *kbuf, *hash;
         DH *dh;
+        int min = -1, max = -1, nbits = -1;
         BIGNUM *shared_secret = NULL;
         BIGNUM *dh_client_pub = NULL;
-        int type =0;
+        int type = 0;
+        int gex;
         u_int slen;
         gss_OID oid;
         
         /* Initialise GSSAPI */
 
+        /* If we're rekeying, privsep means that some of the private structures
+         * in the GSSAPI code are no longer available. This kludges them back
+         * into life
+         */
+        if (!ssh_gssapi_oid_table_ok()) 
+                ssh_gssapi_server_mechanisms();
+
         debug2("%s: Identifying %s", __func__, kex->name);
-        oid = ssh_gssapi_id_kex(NULL, kex->name);
+        oid = ssh_gssapi_id_kex(NULL, kex->name, &gex);
         if (oid == NULL)
            fatal("Unknown gssapi mechanism");
 
@@ -76,6 +86,34 @@ kexgss_server(Kex *kex)
         if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, oid))))
                 fatal("Unable to acquire credentials for the server");
 
+        if (gex) {
+                debug("Doing group exchange");
+                packet_read_expect(SSH2_MSG_KEXGSS_GROUPREQ);
+                min = packet_get_int();
+                nbits = packet_get_int();
+                max = packet_get_int();
+                min = MAX(DH_GRP_MIN, min);
+                max = MIN(DH_GRP_MAX, max);
+                packet_check_eom();
+                if (max < min || nbits < min || max < nbits)
+                        fatal("GSS_GEX, bad parameters: %d !< %d !< %d",
+                            min, nbits, max);
+                dh = PRIVSEP(choose_dh(min, nbits, max));
+                if (dh == NULL)
+                        packet_disconnect("Protocol error: no matching group found");
+
+                packet_start(SSH2_MSG_KEXGSS_GROUP);
+                packet_put_bignum2(dh->p);
+                packet_put_bignum2(dh->g);
+                packet_send();
+
+                packet_write_wait();
+                
+        } else {
+                dh = dh_new_group1();
+        }
+        dh_gen_key(dh, kex->we_need * 8);
+
         do {
                 debug("Wait SSH2_MSG_GSSAPI_INIT");
                 type = packet_read();
@@ -86,10 +124,9 @@ kexgss_server(Kex *kex)
                         recv_tok.value = packet_get_string(&slen);
                         recv_tok.length = slen; 
 
-                        dh_client_pub = BN_new();
-
-                        if (dh_client_pub == NULL)
+                        if ((dh_client_pub = BN_new()) == NULL)
                                 fatal("dh_client_pub == NULL");
+
                         packet_get_bignum2(dh_client_pub);
 
                         /* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
@@ -107,8 +144,8 @@ kexgss_server(Kex *kex)
                 maj_status = PRIVSEP(ssh_gssapi_accept_ctx(ctxt, &recv_tok, 
                     &send_tok, &ret_flags));
 
-                gss_release_buffer(&min_status, &recv_tok);
-                
+                xfree(recv_tok.value);
+
                 if (maj_status != GSS_S_COMPLETE && send_tok.length == 0)
                         fatal("Zero length token output when incomplete");
 
@@ -125,7 +162,7 @@ kexgss_server(Kex *kex)
         } while (maj_status & GSS_S_CONTINUE_NEEDED);
 
         if (GSS_ERROR(maj_status)) {
-                if (send_tok.length>0) {
+                if (send_tok.length > 0) {
                         packet_start(SSH2_MSG_KEXGSS_CONTINUE);
                         packet_put_string(send_tok.value, send_tok.length);
                         packet_send();
@@ -139,9 +176,6 @@ kexgss_server(Kex *kex)
         if (!(ret_flags & GSS_C_INTEG_FLAG))
                 fatal("Integrity flag wasn't set");
         
-        dh = dh_new_group1();
-        dh_gen_key(dh, kex->we_need * 8);
-
         if (!dh_pub_is_valid(dh, dh_client_pub))
                 packet_disconnect("bad client public DH value");
 
@@ -154,14 +188,29 @@ kexgss_server(Kex *kex)
         memset(kbuf, 0, klen);
         xfree(kbuf);
 
-        /* The GSSAPI hash is identical to the Diffie Helman one */
-        hash = kex_dh_hash(
-            kex->client_version_string, kex->server_version_string,
-            buffer_ptr(&kex->peer), buffer_len(&kex->peer),
-            buffer_ptr(&kex->my), buffer_len(&kex->my),
-            NULL, 0, /* Change this if we start sending host keys */
-            dh_client_pub, dh->pub_key, shared_secret
-        );
+        if (gex) {
+                hash = kexgex_hash(
+                    kex->client_version_string, kex->server_version_string,
+                    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
+                    buffer_ptr(&kex->my), buffer_len(&kex->my),
+                    NULL, 0,
+                    min, nbits, max,
+                    dh->p, dh->g,
+                    dh_client_pub,
+                    dh->pub_key,
+                    shared_secret
+                );
+        }
+        else {  
+                /* The GSSAPI hash is identical to the Diffie Helman one */
+                hash = kex_dh_hash(
+                    kex->client_version_string, kex->server_version_string,
+                    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
+                    buffer_ptr(&kex->my), buffer_len(&kex->my),
+                    NULL, 0, /* Change this if we start sending host keys */
+                    dh_client_pub, dh->pub_key, shared_secret
+                );
+        }
         BN_free(dh_client_pub);
 
         if (kex->session_id == NULL) {
@@ -180,7 +229,7 @@ kexgss_server(Kex *kex)
         packet_put_bignum2(dh->pub_key);
         packet_put_string((char *)msg_tok.value,msg_tok.length);
 
-        if (send_tok.length!=0) {
+        if (send_tok.length != 0) {
                 packet_put_char(1); /* true */
                 packet_put_string((char *)send_tok.value, send_tok.length);
         } else {
@@ -188,7 +237,8 @@ kexgss_server(Kex *kex)
         }
         packet_send();
 
-        gss_release_buffer(&min_status, &send_tok);     
+        gss_release_buffer(&min_status, &send_tok);
+        gss_release_buffer(&min_status, &msg_tok);
 
         if (gss_kex_context == NULL)
                 gss_kex_context = ctxt;