304 lines
8.2 KiB
C
304 lines
8.2 KiB
C
/* $OpenBSD: auth2-gss.c,v 1.18 2012/12/02 20:34:09 djm Exp $ */
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/*
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* Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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#ifdef GSSAPI
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#include <sys/types.h>
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#include <stdarg.h>
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#include "xmalloc.h"
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#include "key.h"
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#include "hostfile.h"
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#include "auth.h"
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#include "ssh2.h"
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#include "log.h"
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#include "dispatch.h"
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#include "buffer.h"
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#include "servconf.h"
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#include "packet.h"
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#include "ssh-gss.h"
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#include "monitor_wrap.h"
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extern ServerOptions options;
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static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
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static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt);
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static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
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static void input_gssapi_errtok(int, u_int32_t, void *);
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/*
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* We only support those mechanisms that we know about (ie ones that we know
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* how to check local user kuserok and the like)
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*/
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static int
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userauth_gssapi(Authctxt *authctxt)
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{
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gss_OID_desc goid = {0, NULL};
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Gssctxt *ctxt = NULL;
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int mechs;
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gss_OID_set supported;
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int present;
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OM_uint32 ms;
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u_int len;
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u_char *doid = NULL;
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if (!authctxt->valid || authctxt->user == NULL)
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return (0);
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mechs = packet_get_int();
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if (mechs == 0) {
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debug("Mechanism negotiation is not supported");
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return (0);
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}
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ssh_gssapi_supported_oids(&supported);
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do {
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mechs--;
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if (doid)
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xfree(doid);
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present = 0;
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doid = packet_get_string(&len);
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if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
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doid[1] == len - 2) {
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goid.elements = doid + 2;
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goid.length = len - 2;
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gss_test_oid_set_member(&ms, &goid, supported,
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&present);
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} else {
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logit("Badly formed OID received");
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}
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} while (mechs > 0 && !present);
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gss_release_oid_set(&ms, &supported);
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if (!present) {
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xfree(doid);
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authctxt->server_caused_failure = 1;
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return (0);
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}
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if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
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if (ctxt != NULL)
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ssh_gssapi_delete_ctx(&ctxt);
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xfree(doid);
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authctxt->server_caused_failure = 1;
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return (0);
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}
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authctxt->methoddata = (void *)ctxt;
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packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
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/* Return the OID that we received */
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packet_put_string(doid, len);
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packet_send();
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xfree(doid);
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
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authctxt->postponed = 1;
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return (0);
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}
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static void
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input_gssapi_token(int type, u_int32_t plen, void *ctxt)
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{
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Authctxt *authctxt = ctxt;
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Gssctxt *gssctxt;
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gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
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gss_buffer_desc recv_tok;
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OM_uint32 maj_status, min_status, flags;
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u_int len;
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if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
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fatal("No authentication or GSSAPI context");
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gssctxt = authctxt->methoddata;
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recv_tok.value = packet_get_string(&len);
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recv_tok.length = len; /* u_int vs. size_t */
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packet_check_eom();
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maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
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&send_tok, &flags));
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xfree(recv_tok.value);
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if (GSS_ERROR(maj_status)) {
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if (send_tok.length != 0) {
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packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
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packet_put_string(send_tok.value, send_tok.length);
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packet_send();
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}
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authctxt->postponed = 0;
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
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userauth_finish(authctxt, 0, "gssapi-with-mic", NULL);
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} else {
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if (send_tok.length != 0) {
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packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
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packet_put_string(send_tok.value, send_tok.length);
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packet_send();
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}
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if (maj_status == GSS_S_COMPLETE) {
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
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if (flags & GSS_C_INTEG_FLAG)
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC,
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&input_gssapi_mic);
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else
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dispatch_set(
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SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
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&input_gssapi_exchange_complete);
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}
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}
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gss_release_buffer(&min_status, &send_tok);
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}
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static void
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input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
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{
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Authctxt *authctxt = ctxt;
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Gssctxt *gssctxt;
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gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
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gss_buffer_desc recv_tok;
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OM_uint32 maj_status;
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u_int len;
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if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
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fatal("No authentication or GSSAPI context");
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gssctxt = authctxt->methoddata;
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recv_tok.value = packet_get_string(&len);
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recv_tok.length = len;
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packet_check_eom();
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/* Push the error token into GSSAPI to see what it says */
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maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
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&send_tok, NULL));
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xfree(recv_tok.value);
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/* We can't return anything to the client, even if we wanted to */
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
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/* The client will have already moved on to the next auth */
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gss_release_buffer(&maj_status, &send_tok);
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}
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/*
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* This is called when the client thinks we've completed authentication.
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* It should only be enabled in the dispatch handler by the function above,
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* which only enables it once the GSSAPI exchange is complete.
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*/
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static void
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input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
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{
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Authctxt *authctxt = ctxt;
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Gssctxt *gssctxt;
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int authenticated;
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if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
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fatal("No authentication or GSSAPI context");
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gssctxt = authctxt->methoddata;
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/*
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* We don't need to check the status, because we're only enabled in
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* the dispatcher once the exchange is complete
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*/
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packet_check_eom();
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authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
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authctxt->postponed = 0;
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
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userauth_finish(authctxt, authenticated, "gssapi-with-mic", NULL);
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}
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static void
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input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
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{
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Authctxt *authctxt = ctxt;
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Gssctxt *gssctxt;
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int authenticated = 0;
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Buffer b;
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gss_buffer_desc mic, gssbuf;
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u_int len;
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if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
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fatal("No authentication or GSSAPI context");
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gssctxt = authctxt->methoddata;
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mic.value = packet_get_string(&len);
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mic.length = len;
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ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
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"gssapi-with-mic");
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gssbuf.value = buffer_ptr(&b);
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gssbuf.length = buffer_len(&b);
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if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
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authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
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else
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logit("GSSAPI MIC check failed");
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buffer_free(&b);
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xfree(mic.value);
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authctxt->postponed = 0;
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
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dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
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userauth_finish(authctxt, authenticated, "gssapi-with-mic", NULL);
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}
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Authmethod method_gssapi = {
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"gssapi-with-mic",
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userauth_gssapi,
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&options.gss_authentication
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};
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#endif /* GSSAPI */
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