--- /dev/null
+/*
+ * 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
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#ifdef GSSAPI
+
+#include "includes.h"
+
+#include <openssl/crypto.h>
+#include <openssl/bn.h>
+
+#include <string.h>
+
+#include "xmalloc.h"
+#include "buffer.h"
+#include "ssh2.h"
+#include "key.h"
+#include "cipher.h"
+#include "kex.h"
+#include "log.h"
+#include "packet.h"
+#include "dh.h"
+
+#include "ssh-gss.h"
+
+void
+kexgss_client(Kex *kex) {
+ gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
+ gss_buffer_desc recv_tok, gssbuf, msg_tok, *token_ptr;
+ Gssctxt *ctxt;
+ OM_uint32 maj_status, min_status, ret_flags;
+ u_int klen, kout, slen = 0, hashlen, strlen;
+ DH *dh;
+ BIGNUM *dh_server_pub = NULL;
+ BIGNUM *shared_secret = NULL;
+ BIGNUM *p = NULL;
+ BIGNUM *g = NULL;
+ u_char *kbuf, *hash;
+ u_char *serverhostkey = NULL;
+ u_char *empty = "";
+ char *msg;
+ char *lang;
+ int type = 0;
+ int first = 1;
+ int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX;
+
+ /* Initialise our GSSAPI world */
+ ssh_gssapi_build_ctx(&ctxt);
+ if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type)
+ == GSS_C_NO_OID)
+ fatal("Couldn't identify host exchange");
+
+ if (ssh_gssapi_import_name(ctxt, kex->gss_host))
+ fatal("Couldn't import hostname");
+
+ if (kex->gss_client &&
+ ssh_gssapi_client_identity(ctxt, kex->gss_client))
+ fatal("Couldn't acquire client credentials");
+
+ switch (kex->kex_type) {
+ case KEX_GSS_GRP1_SHA1:
+ dh = dh_new_group1();
+ break;
+ case KEX_GSS_GRP14_SHA1:
+ dh = dh_new_group14();
+ break;
+ case KEX_GSS_GEX_SHA1:
+ debug("Doing group exchange\n");
+ nbits = dh_estimate(kex->we_need * 8);
+ packet_start(SSH2_MSG_KEXGSS_GROUPREQ);
+ packet_put_int(min);
+ packet_put_int(nbits);
+ packet_put_int(max);
+
+ packet_send();
+
+ packet_read_expect(SSH2_MSG_KEXGSS_GROUP);
+
+ if ((p = BN_new()) == NULL)
+ fatal("BN_new() failed");
+ packet_get_bignum2(p);
+ if ((g = BN_new()) == NULL)
+ fatal("BN_new() failed");
+ packet_get_bignum2(g);
+ packet_check_eom();
+
+ if (BN_num_bits(p) < min || BN_num_bits(p) > max)
+ fatal("GSSGRP_GEX group out of range: %d !< %d !< %d",
+ min, BN_num_bits(p), max);
+
+ dh = dh_new_group(g, p);
+ break;
+ default:
+ fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
+ }
+
+ /* Step 1 - e is dh->pub_key */
+ dh_gen_key(dh, kex->we_need * 8);
+
+ /* This is f, we initialise it now to make life easier */
+ dh_server_pub = BN_new();
+ if (dh_server_pub == NULL)
+ fatal("dh_server_pub == NULL");
+
+ token_ptr = GSS_C_NO_BUFFER;
+
+ do {
+ debug("Calling gss_init_sec_context");
+
+ maj_status = ssh_gssapi_init_ctx(ctxt,
+ kex->gss_deleg_creds, token_ptr, &send_tok,
+ &ret_flags);
+
+ if (GSS_ERROR(maj_status)) {
+ if (send_tok.length != 0) {
+ packet_start(SSH2_MSG_KEXGSS_CONTINUE);
+ packet_put_string(send_tok.value,
+ send_tok.length);
+ }
+ fatal("gss_init_context failed");
+ }
+
+ /* If we've got an old receive buffer get rid of it */
+ if (token_ptr != GSS_C_NO_BUFFER)
+ xfree(recv_tok.value);
+
+ if (maj_status == GSS_S_COMPLETE) {
+ /* If mutual state flag is not true, kex fails */
+ if (!(ret_flags & GSS_C_MUTUAL_FLAG))
+ fatal("Mutual authentication failed");
+
+ /* If integ avail flag is not true kex fails */
+ if (!(ret_flags & GSS_C_INTEG_FLAG))
+ fatal("Integrity check failed");
+ }
+
+ /*
+ * If we have data to send, then the last message that we
+ * received cannot have been a 'complete'.
+ */
+ if (send_tok.length != 0) {
+ if (first) {
+ packet_start(SSH2_MSG_KEXGSS_INIT);
+ packet_put_string(send_tok.value,
+ send_tok.length);
+ packet_put_bignum2(dh->pub_key);
+ first = 0;
+ } else {
+ packet_start(SSH2_MSG_KEXGSS_CONTINUE);
+ packet_put_string(send_tok.value,
+ send_tok.length);
+ }
+ packet_send();
+ gss_release_buffer(&min_status, &send_tok);
+
+ /* If we've sent them data, they should reply */
+ do {
+ type = packet_read();
+ if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
+ debug("Received KEXGSS_HOSTKEY");
+ if (serverhostkey)
+ fatal("Server host key received more than once");
+ serverhostkey =
+ packet_get_string(&slen);
+ }
+ } while (type == SSH2_MSG_KEXGSS_HOSTKEY);
+
+ switch (type) {
+ case SSH2_MSG_KEXGSS_CONTINUE:
+ debug("Received GSSAPI_CONTINUE");
+ if (maj_status == GSS_S_COMPLETE)
+ fatal("GSSAPI Continue received from server when complete");
+ recv_tok.value = packet_get_string(&strlen);
+ recv_tok.length = strlen;
+ break;
+ case SSH2_MSG_KEXGSS_COMPLETE:
+ debug("Received GSSAPI_COMPLETE");
+ packet_get_bignum2(dh_server_pub);
+ msg_tok.value = packet_get_string(&strlen);
+ msg_tok.length = strlen;
+
+ /* Is there a token included? */
+ if (packet_get_char()) {
+ recv_tok.value=
+ packet_get_string(&strlen);
+ recv_tok.length = strlen;
+ /* If we're already complete - protocol error */
+ if (maj_status == GSS_S_COMPLETE)
+ packet_disconnect("Protocol error: received token when complete");
+ } else {
+ /* No token included */
+ if (maj_status != GSS_S_COMPLETE)
+ packet_disconnect("Protocol error: did not receive final token");
+ }
+ break;
+ case SSH2_MSG_KEXGSS_ERROR:
+ debug("Received Error");
+ maj_status = packet_get_int();
+ min_status = packet_get_int();
+ msg = packet_get_string(NULL);
+ lang = packet_get_string(NULL);
+ fatal("GSSAPI Error: \n%.400s",msg);
+ default:
+ packet_disconnect("Protocol error: didn't expect packet type %d",
+ type);
+ }
+ token_ptr = &recv_tok;
+ } else {
+ /* No data, and not complete */
+ if (maj_status != GSS_S_COMPLETE)
+ fatal("Not complete, and no token output");
+ }
+ } while (maj_status & GSS_S_CONTINUE_NEEDED);
+
+ /*
+ * We _must_ have received a COMPLETE message in reply from the
+ * server, which will have set dh_server_pub and msg_tok
+ */
+
+ if (type != SSH2_MSG_KEXGSS_COMPLETE)
+ fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");
+
+ /* Check f in range [1, p-1] */
+ if (!dh_pub_is_valid(dh, dh_server_pub))
+ packet_disconnect("bad server public DH value");
+
+ /* compute K=f^x mod p */
+ klen = DH_size(dh);
+ kbuf = xmalloc(klen);
+ kout = DH_compute_key(kbuf, dh_server_pub, dh);
+ if (kout < 0)
+ fatal("DH_compute_key: failed");
+
+ shared_secret = BN_new();
+ if (shared_secret == NULL)
+ fatal("kexgss_client: BN_new failed");
+
+ if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
+ fatal("kexdh_client: BN_bin2bn failed");
+
+ memset(kbuf, 0, klen);
+ xfree(kbuf);
+
+ switch (kex->kex_type) {
+ case KEX_GSS_GRP1_SHA1:
+ case KEX_GSS_GRP14_SHA1:
+ kex_dh_hash( kex->client_version_string,
+ kex->server_version_string,
+ buffer_ptr(&kex->my), buffer_len(&kex->my),
+ buffer_ptr(&kex->peer), buffer_len(&kex->peer),
+ (serverhostkey ? serverhostkey : empty), slen,
+ dh->pub_key, /* e */
+ dh_server_pub, /* f */
+ shared_secret, /* K */
+ &hash, &hashlen
+ );
+ break;
+ case KEX_GSS_GEX_SHA1:
+ kexgex_hash(
+ kex->evp_md,
+ kex->client_version_string,
+ kex->server_version_string,
+ buffer_ptr(&kex->my), buffer_len(&kex->my),
+ buffer_ptr(&kex->peer), buffer_len(&kex->peer),
+ (serverhostkey ? serverhostkey : empty), slen,
+ min, nbits, max,
+ dh->p, dh->g,
+ dh->pub_key,
+ dh_server_pub,
+ shared_secret,
+ &hash, &hashlen
+ );
+ break;
+ default:
+ fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
+ }
+
+ gssbuf.value = hash;
+ gssbuf.length = hashlen;
+
+ /* Verify that the hash matches the MIC we just got. */
+ if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok)))
+ packet_disconnect("Hash's MIC didn't verify");
+
+ xfree(msg_tok.value);
+
+ DH_free(dh);
+ if (serverhostkey)
+ xfree(serverhostkey);
+ BN_clear_free(dh_server_pub);
+
+ /* save session id */
+ if (kex->session_id == NULL) {
+ kex->session_id_len = hashlen;
+ kex->session_id = xmalloc(kex->session_id_len);
+ memcpy(kex->session_id, hash, kex->session_id_len);
+ }
+
+ if (kex->gss_deleg_creds)
+ ssh_gssapi_credentials_updated(ctxt);
+
+ if (gss_kex_context == NULL)
+ gss_kex_context = ctxt;
+ else
+ ssh_gssapi_delete_ctx(&ctxt);
+
+ kex_derive_keys(kex, hash, hashlen, shared_secret);
+ BN_clear_free(shared_secret);
+ kex_finish(kex);
+}
+
+#endif /* GSSAPI */
projects / openssh.git / blobdiff