d4af9e693f
I have worked hard to reduce diffs against the vendor branch. One notable change in that respect is that we no longer prefer DSA over RSA - the reasons for doing so went away years ago. This may cause some surprises, as ssh will warn about unknown host keys even for hosts whose keys haven't changed. MFC after: 6 weeks
379 lines
9.0 KiB
C
379 lines
9.0 KiB
C
/* $OpenBSD: auth2-chall.c,v 1.33 2007/09/21 08:15:29 djm Exp $ */
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/*
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* Copyright (c) 2001 Markus Friedl. All rights reserved.
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* Copyright (c) 2001 Per Allansson. 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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#include <sys/types.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <string.h>
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#include "xmalloc.h"
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#include "ssh2.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 "buffer.h"
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#include "packet.h"
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#include "dispatch.h"
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#include "log.h"
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#include "servconf.h"
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/* import */
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extern ServerOptions options;
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static int auth2_challenge_start(Authctxt *);
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static int send_userauth_info_request(Authctxt *);
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static void input_userauth_info_response(int, u_int32_t, void *);
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#ifdef BSD_AUTH
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extern KbdintDevice bsdauth_device;
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#else
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#ifdef USE_PAM
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extern KbdintDevice sshpam_device;
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#endif
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#ifdef SKEY
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extern KbdintDevice skey_device;
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#endif
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#endif
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KbdintDevice *devices[] = {
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#ifdef BSD_AUTH
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&bsdauth_device,
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#else
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#ifdef USE_PAM
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&sshpam_device,
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#endif
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#ifdef SKEY
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&skey_device,
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#endif
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#endif
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NULL
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};
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typedef struct KbdintAuthctxt KbdintAuthctxt;
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struct KbdintAuthctxt
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{
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char *devices;
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void *ctxt;
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KbdintDevice *device;
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u_int nreq;
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};
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#ifdef USE_PAM
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void
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remove_kbdint_device(const char *devname)
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{
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int i, j;
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for (i = 0; devices[i] != NULL; i++)
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if (strcmp(devices[i]->name, devname) == 0) {
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for (j = i; devices[j] != NULL; j++)
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devices[j] = devices[j+1];
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i--;
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}
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}
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#endif
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static KbdintAuthctxt *
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kbdint_alloc(const char *devs)
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{
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KbdintAuthctxt *kbdintctxt;
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Buffer b;
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int i;
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#ifdef USE_PAM
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if (!options.use_pam)
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remove_kbdint_device("pam");
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#endif
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kbdintctxt = xmalloc(sizeof(KbdintAuthctxt));
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if (strcmp(devs, "") == 0) {
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buffer_init(&b);
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for (i = 0; devices[i]; i++) {
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if (buffer_len(&b) > 0)
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buffer_append(&b, ",", 1);
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buffer_append(&b, devices[i]->name,
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strlen(devices[i]->name));
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}
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buffer_append(&b, "\0", 1);
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kbdintctxt->devices = xstrdup(buffer_ptr(&b));
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buffer_free(&b);
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} else {
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kbdintctxt->devices = xstrdup(devs);
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}
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debug("kbdint_alloc: devices '%s'", kbdintctxt->devices);
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kbdintctxt->ctxt = NULL;
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kbdintctxt->device = NULL;
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kbdintctxt->nreq = 0;
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return kbdintctxt;
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}
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static void
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kbdint_reset_device(KbdintAuthctxt *kbdintctxt)
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{
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if (kbdintctxt->ctxt) {
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kbdintctxt->device->free_ctx(kbdintctxt->ctxt);
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kbdintctxt->ctxt = NULL;
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}
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kbdintctxt->device = NULL;
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}
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static void
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kbdint_free(KbdintAuthctxt *kbdintctxt)
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{
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if (kbdintctxt->device)
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kbdint_reset_device(kbdintctxt);
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if (kbdintctxt->devices) {
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xfree(kbdintctxt->devices);
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kbdintctxt->devices = NULL;
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}
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xfree(kbdintctxt);
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}
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/* get next device */
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static int
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kbdint_next_device(KbdintAuthctxt *kbdintctxt)
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{
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size_t len;
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char *t;
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int i;
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if (kbdintctxt->device)
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kbdint_reset_device(kbdintctxt);
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do {
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len = kbdintctxt->devices ?
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strcspn(kbdintctxt->devices, ",") : 0;
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if (len == 0)
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break;
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for (i = 0; devices[i]; i++)
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if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0)
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kbdintctxt->device = devices[i];
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t = kbdintctxt->devices;
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kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL;
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xfree(t);
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debug2("kbdint_next_device: devices %s", kbdintctxt->devices ?
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kbdintctxt->devices : "<empty>");
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} while (kbdintctxt->devices && !kbdintctxt->device);
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return kbdintctxt->device ? 1 : 0;
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}
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/*
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* try challenge-response, set authctxt->postponed if we have to
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* wait for the response.
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*/
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int
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auth2_challenge(Authctxt *authctxt, char *devs)
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{
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debug("auth2_challenge: user=%s devs=%s",
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authctxt->user ? authctxt->user : "<nouser>",
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devs ? devs : "<no devs>");
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if (authctxt->user == NULL || !devs)
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return 0;
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if (authctxt->kbdintctxt == NULL)
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authctxt->kbdintctxt = kbdint_alloc(devs);
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return auth2_challenge_start(authctxt);
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}
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/* unregister kbd-int callbacks and context */
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void
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auth2_challenge_stop(Authctxt *authctxt)
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{
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/* unregister callback */
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dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL);
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if (authctxt->kbdintctxt != NULL) {
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kbdint_free(authctxt->kbdintctxt);
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authctxt->kbdintctxt = NULL;
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}
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}
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/* side effect: sets authctxt->postponed if a reply was sent*/
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static int
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auth2_challenge_start(Authctxt *authctxt)
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{
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KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt;
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debug2("auth2_challenge_start: devices %s",
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kbdintctxt->devices ? kbdintctxt->devices : "<empty>");
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if (kbdint_next_device(kbdintctxt) == 0) {
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auth2_challenge_stop(authctxt);
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return 0;
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}
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debug("auth2_challenge_start: trying authentication method '%s'",
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kbdintctxt->device->name);
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if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) {
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auth2_challenge_stop(authctxt);
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return 0;
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}
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if (send_userauth_info_request(authctxt) == 0) {
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auth2_challenge_stop(authctxt);
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return 0;
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}
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dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE,
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&input_userauth_info_response);
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authctxt->postponed = 1;
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return 0;
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}
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static int
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send_userauth_info_request(Authctxt *authctxt)
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{
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KbdintAuthctxt *kbdintctxt;
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char *name, *instr, **prompts;
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u_int i, *echo_on;
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kbdintctxt = authctxt->kbdintctxt;
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if (kbdintctxt->device->query(kbdintctxt->ctxt,
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&name, &instr, &kbdintctxt->nreq, &prompts, &echo_on))
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return 0;
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packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST);
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packet_put_cstring(name);
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packet_put_cstring(instr);
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packet_put_cstring(""); /* language not used */
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packet_put_int(kbdintctxt->nreq);
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for (i = 0; i < kbdintctxt->nreq; i++) {
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packet_put_cstring(prompts[i]);
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packet_put_char(echo_on[i]);
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}
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packet_send();
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packet_write_wait();
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for (i = 0; i < kbdintctxt->nreq; i++)
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xfree(prompts[i]);
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xfree(prompts);
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xfree(echo_on);
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xfree(name);
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xfree(instr);
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return 1;
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}
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static void
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input_userauth_info_response(int type, u_int32_t seq, void *ctxt)
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{
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Authctxt *authctxt = ctxt;
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KbdintAuthctxt *kbdintctxt;
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int authenticated = 0, res, len;
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u_int i, nresp;
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char **response = NULL, *method;
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if (authctxt == NULL)
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fatal("input_userauth_info_response: no authctxt");
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kbdintctxt = authctxt->kbdintctxt;
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if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL)
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fatal("input_userauth_info_response: no kbdintctxt");
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if (kbdintctxt->device == NULL)
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fatal("input_userauth_info_response: no device");
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authctxt->postponed = 0; /* reset */
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nresp = packet_get_int();
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if (nresp != kbdintctxt->nreq)
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fatal("input_userauth_info_response: wrong number of replies");
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if (nresp > 100)
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fatal("input_userauth_info_response: too many replies");
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if (nresp > 0) {
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response = xcalloc(nresp, sizeof(char *));
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for (i = 0; i < nresp; i++)
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response[i] = packet_get_string(NULL);
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}
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packet_check_eom();
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res = kbdintctxt->device->respond(kbdintctxt->ctxt, nresp, response);
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for (i = 0; i < nresp; i++) {
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memset(response[i], 'r', strlen(response[i]));
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xfree(response[i]);
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}
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if (response)
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xfree(response);
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switch (res) {
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case 0:
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/* Success! */
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authenticated = authctxt->valid ? 1 : 0;
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break;
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case 1:
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/* Authentication needs further interaction */
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if (send_userauth_info_request(authctxt) == 1)
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authctxt->postponed = 1;
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break;
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default:
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/* Failure! */
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break;
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}
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len = strlen("keyboard-interactive") + 2 +
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strlen(kbdintctxt->device->name);
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method = xmalloc(len);
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snprintf(method, len, "keyboard-interactive/%s",
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kbdintctxt->device->name);
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if (!authctxt->postponed) {
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if (authenticated) {
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auth2_challenge_stop(authctxt);
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} else {
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/* start next device */
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/* may set authctxt->postponed */
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auth2_challenge_start(authctxt);
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}
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}
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userauth_finish(authctxt, authenticated, method);
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xfree(method);
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}
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void
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privsep_challenge_enable(void)
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{
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#if defined(BSD_AUTH) || defined(USE_PAM) || defined(SKEY)
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int n = 0;
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#endif
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#ifdef BSD_AUTH
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extern KbdintDevice mm_bsdauth_device;
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#endif
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#ifdef USE_PAM
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extern KbdintDevice mm_sshpam_device;
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#endif
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#ifdef SKEY
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extern KbdintDevice mm_skey_device;
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#endif
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#ifdef BSD_AUTH
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devices[n++] = &mm_bsdauth_device;
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#else
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#ifdef USE_PAM
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devices[n++] = &mm_sshpam_device;
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#endif
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#ifdef SKEY
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devices[n++] = &mm_skey_device;
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#endif
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#endif
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}
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