1264377Sdes/* $OpenBSD: auth2-chall.c,v 1.41 2014/02/02 03:44:31 djm Exp $ */ 276259Sgreen/* 376259Sgreen * Copyright (c) 2001 Markus Friedl. All rights reserved. 492555Sdes * Copyright (c) 2001 Per Allansson. All rights reserved. 576259Sgreen * 676259Sgreen * Redistribution and use in source and binary forms, with or without 776259Sgreen * modification, are permitted provided that the following conditions 876259Sgreen * are met: 976259Sgreen * 1. Redistributions of source code must retain the above copyright 1076259Sgreen * notice, this list of conditions and the following disclaimer. 1176259Sgreen * 2. Redistributions in binary form must reproduce the above copyright 1276259Sgreen * notice, this list of conditions and the following disclaimer in the 1376259Sgreen * documentation and/or other materials provided with the distribution. 1476259Sgreen * 1576259Sgreen * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 1676259Sgreen * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 1776259Sgreen * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 1876259Sgreen * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 1976259Sgreen * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 2076259Sgreen * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 2176259Sgreen * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 2276259Sgreen * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 2376259Sgreen * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 2476259Sgreen * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 2576259Sgreen */ 26162856Sdes 2776259Sgreen#include "includes.h" 2876259Sgreen 29162856Sdes#include <sys/types.h> 30162856Sdes 31162856Sdes#include <stdarg.h> 32162856Sdes#include <stdio.h> 33162856Sdes#include <string.h> 34162856Sdes 35162856Sdes#include "xmalloc.h" 3676259Sgreen#include "ssh2.h" 37162856Sdes#include "key.h" 38162856Sdes#include "hostfile.h" 3976259Sgreen#include "auth.h" 4092555Sdes#include "buffer.h" 4176259Sgreen#include "packet.h" 4276259Sgreen#include "dispatch.h" 4376259Sgreen#include "log.h" 44147005Sdes#include "servconf.h" 4576259Sgreen 46147005Sdes/* import */ 47147005Sdesextern ServerOptions options; 48147005Sdes 4992555Sdesstatic int auth2_challenge_start(Authctxt *); 5092555Sdesstatic int send_userauth_info_request(Authctxt *); 5192555Sdesstatic void input_userauth_info_response(int, u_int32_t, void *); 5276259Sgreen 5392555Sdes#ifdef BSD_AUTH 5492555Sdesextern KbdintDevice bsdauth_device; 5598941Sdes#else 5699052Sdes#ifdef USE_PAM 57124211Sdesextern KbdintDevice sshpam_device; 5899052Sdes#endif 5998941Sdes#ifdef SKEY 6092555Sdesextern KbdintDevice skey_device; 6192555Sdes#endif 6298941Sdes#endif 6392555Sdes 6492555SdesKbdintDevice *devices[] = { 6592555Sdes#ifdef BSD_AUTH 6692555Sdes &bsdauth_device, 6798941Sdes#else 6899052Sdes#ifdef USE_PAM 69124211Sdes &sshpam_device, 7099052Sdes#endif 7198941Sdes#ifdef SKEY 7292555Sdes &skey_device, 7392555Sdes#endif 7498941Sdes#endif 7592555Sdes NULL 7692555Sdes}; 7792555Sdes 7892555Sdestypedef struct KbdintAuthctxt KbdintAuthctxt; 7992555Sdesstruct KbdintAuthctxt 8092555Sdes{ 8192555Sdes char *devices; 8292555Sdes void *ctxt; 8392555Sdes KbdintDevice *device; 8499063Sdes u_int nreq; 85285979Sdelphij u_int devices_done; 8692555Sdes}; 8792555Sdes 88147005Sdes#ifdef USE_PAM 89147005Sdesvoid 90147005Sdesremove_kbdint_device(const char *devname) 91147005Sdes{ 92147005Sdes int i, j; 93147005Sdes 94147005Sdes for (i = 0; devices[i] != NULL; i++) 95147005Sdes if (strcmp(devices[i]->name, devname) == 0) { 96147005Sdes for (j = i; devices[j] != NULL; j++) 97147005Sdes devices[j] = devices[j+1]; 98147005Sdes i--; 99147005Sdes } 100147005Sdes} 101147005Sdes#endif 102147005Sdes 10392555Sdesstatic KbdintAuthctxt * 10492555Sdeskbdint_alloc(const char *devs) 10592555Sdes{ 10692555Sdes KbdintAuthctxt *kbdintctxt; 10792555Sdes Buffer b; 10892555Sdes int i; 10992555Sdes 110147005Sdes#ifdef USE_PAM 111147005Sdes if (!options.use_pam) 112147005Sdes remove_kbdint_device("pam"); 113147005Sdes#endif 114147005Sdes 115258343Sdes kbdintctxt = xcalloc(1, sizeof(KbdintAuthctxt)); 11692555Sdes if (strcmp(devs, "") == 0) { 11792555Sdes buffer_init(&b); 11892555Sdes for (i = 0; devices[i]; i++) { 11992555Sdes if (buffer_len(&b) > 0) 12092555Sdes buffer_append(&b, ",", 1); 12192555Sdes buffer_append(&b, devices[i]->name, 12292555Sdes strlen(devices[i]->name)); 12392555Sdes } 12492555Sdes buffer_append(&b, "\0", 1); 12592555Sdes kbdintctxt->devices = xstrdup(buffer_ptr(&b)); 12692555Sdes buffer_free(&b); 12792555Sdes } else { 12892555Sdes kbdintctxt->devices = xstrdup(devs); 12992555Sdes } 13092555Sdes debug("kbdint_alloc: devices '%s'", kbdintctxt->devices); 13192555Sdes kbdintctxt->ctxt = NULL; 13292555Sdes kbdintctxt->device = NULL; 13399063Sdes kbdintctxt->nreq = 0; 13492555Sdes 13592555Sdes return kbdintctxt; 13692555Sdes} 13792555Sdesstatic void 13892555Sdeskbdint_reset_device(KbdintAuthctxt *kbdintctxt) 13992555Sdes{ 14092555Sdes if (kbdintctxt->ctxt) { 14192555Sdes kbdintctxt->device->free_ctx(kbdintctxt->ctxt); 14292555Sdes kbdintctxt->ctxt = NULL; 14392555Sdes } 14492555Sdes kbdintctxt->device = NULL; 14592555Sdes} 14692555Sdesstatic void 14792555Sdeskbdint_free(KbdintAuthctxt *kbdintctxt) 14892555Sdes{ 14992555Sdes if (kbdintctxt->device) 15092555Sdes kbdint_reset_device(kbdintctxt); 151255767Sdes free(kbdintctxt->devices); 152264377Sdes explicit_bzero(kbdintctxt, sizeof(*kbdintctxt)); 153255767Sdes free(kbdintctxt); 15492555Sdes} 15592555Sdes/* get next device */ 15692555Sdesstatic int 157255767Sdeskbdint_next_device(Authctxt *authctxt, KbdintAuthctxt *kbdintctxt) 15892555Sdes{ 15992555Sdes size_t len; 16092555Sdes char *t; 16192555Sdes int i; 16292555Sdes 16392555Sdes if (kbdintctxt->device) 16492555Sdes kbdint_reset_device(kbdintctxt); 16592555Sdes do { 16692555Sdes len = kbdintctxt->devices ? 16792555Sdes strcspn(kbdintctxt->devices, ",") : 0; 16892555Sdes 16992555Sdes if (len == 0) 17092555Sdes break; 171255767Sdes for (i = 0; devices[i]; i++) { 172285979Sdelphij if ((kbdintctxt->devices_done & (1 << i)) != 0 || 173285979Sdelphij !auth2_method_allowed(authctxt, 174255767Sdes "keyboard-interactive", devices[i]->name)) 175255767Sdes continue; 176285979Sdelphij if (strncmp(kbdintctxt->devices, devices[i]->name, 177285979Sdelphij len) == 0) { 17892555Sdes kbdintctxt->device = devices[i]; 179285979Sdelphij kbdintctxt->devices_done |= 1 << i; 180285979Sdelphij } 181255767Sdes } 18292555Sdes t = kbdintctxt->devices; 18392555Sdes kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL; 184255767Sdes free(t); 18592555Sdes debug2("kbdint_next_device: devices %s", kbdintctxt->devices ? 186149753Sdes kbdintctxt->devices : "<empty>"); 18792555Sdes } while (kbdintctxt->devices && !kbdintctxt->device); 18892555Sdes 18992555Sdes return kbdintctxt->device ? 1 : 0; 19092555Sdes} 19192555Sdes 19276259Sgreen/* 19392555Sdes * try challenge-response, set authctxt->postponed if we have to 19476259Sgreen * wait for the response. 19576259Sgreen */ 19676259Sgreenint 19776259Sgreenauth2_challenge(Authctxt *authctxt, char *devs) 19876259Sgreen{ 19992555Sdes debug("auth2_challenge: user=%s devs=%s", 20092555Sdes authctxt->user ? authctxt->user : "<nouser>", 20192555Sdes devs ? devs : "<no devs>"); 20276259Sgreen 20392555Sdes if (authctxt->user == NULL || !devs) 20476259Sgreen return 0; 20592555Sdes if (authctxt->kbdintctxt == NULL) 20692555Sdes authctxt->kbdintctxt = kbdint_alloc(devs); 20792555Sdes return auth2_challenge_start(authctxt); 20892555Sdes} 20992555Sdes 21092555Sdes/* unregister kbd-int callbacks and context */ 21192555Sdesvoid 21292555Sdesauth2_challenge_stop(Authctxt *authctxt) 21392555Sdes{ 21492555Sdes /* unregister callback */ 21592555Sdes dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL); 216181111Sdes if (authctxt->kbdintctxt != NULL) { 21792555Sdes kbdint_free(authctxt->kbdintctxt); 21892555Sdes authctxt->kbdintctxt = NULL; 21992555Sdes } 22092555Sdes} 22192555Sdes 22292555Sdes/* side effect: sets authctxt->postponed if a reply was sent*/ 22392555Sdesstatic int 22492555Sdesauth2_challenge_start(Authctxt *authctxt) 22592555Sdes{ 22692555Sdes KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt; 22792555Sdes 22892555Sdes debug2("auth2_challenge_start: devices %s", 22992555Sdes kbdintctxt->devices ? kbdintctxt->devices : "<empty>"); 23092555Sdes 231255767Sdes if (kbdint_next_device(authctxt, kbdintctxt) == 0) { 23292555Sdes auth2_challenge_stop(authctxt); 23376259Sgreen return 0; 23492555Sdes } 23592555Sdes debug("auth2_challenge_start: trying authentication method '%s'", 23692555Sdes kbdintctxt->device->name); 23792555Sdes 23892555Sdes if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) { 23992555Sdes auth2_challenge_stop(authctxt); 24092555Sdes return 0; 24192555Sdes } 24292555Sdes if (send_userauth_info_request(authctxt) == 0) { 24392555Sdes auth2_challenge_stop(authctxt); 24492555Sdes return 0; 24592555Sdes } 24676259Sgreen dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, 24776259Sgreen &input_userauth_info_response); 24892555Sdes 24976259Sgreen authctxt->postponed = 1; 25076259Sgreen return 0; 25176259Sgreen} 25276259Sgreen 25392555Sdesstatic int 25492555Sdessend_userauth_info_request(Authctxt *authctxt) 25576259Sgreen{ 25692555Sdes KbdintAuthctxt *kbdintctxt; 25792555Sdes char *name, *instr, **prompts; 258149753Sdes u_int i, *echo_on; 25976259Sgreen 26092555Sdes kbdintctxt = authctxt->kbdintctxt; 26192555Sdes if (kbdintctxt->device->query(kbdintctxt->ctxt, 26299063Sdes &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on)) 26392555Sdes return 0; 26492555Sdes 26576259Sgreen packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST); 26692555Sdes packet_put_cstring(name); 26792555Sdes packet_put_cstring(instr); 26898684Sdes packet_put_cstring(""); /* language not used */ 26999063Sdes packet_put_int(kbdintctxt->nreq); 27099063Sdes for (i = 0; i < kbdintctxt->nreq; i++) { 27192555Sdes packet_put_cstring(prompts[i]); 27292555Sdes packet_put_char(echo_on[i]); 27392555Sdes } 27476259Sgreen packet_send(); 27576259Sgreen packet_write_wait(); 27692555Sdes 27799063Sdes for (i = 0; i < kbdintctxt->nreq; i++) 278255767Sdes free(prompts[i]); 279255767Sdes free(prompts); 280255767Sdes free(echo_on); 281255767Sdes free(name); 282255767Sdes free(instr); 28392555Sdes return 1; 28476259Sgreen} 28576259Sgreen 28692555Sdesstatic void 28792555Sdesinput_userauth_info_response(int type, u_int32_t seq, void *ctxt) 28876259Sgreen{ 28976259Sgreen Authctxt *authctxt = ctxt; 29092555Sdes KbdintAuthctxt *kbdintctxt; 291192595Sdes int authenticated = 0, res; 292149753Sdes u_int i, nresp; 293248619Sdes const char *devicename = NULL; 294248619Sdes char **response = NULL; 29576259Sgreen 29676259Sgreen if (authctxt == NULL) 29776259Sgreen fatal("input_userauth_info_response: no authctxt"); 29892555Sdes kbdintctxt = authctxt->kbdintctxt; 29992555Sdes if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL) 30092555Sdes fatal("input_userauth_info_response: no kbdintctxt"); 30192555Sdes if (kbdintctxt->device == NULL) 30292555Sdes fatal("input_userauth_info_response: no device"); 30376259Sgreen 30476259Sgreen authctxt->postponed = 0; /* reset */ 30576259Sgreen nresp = packet_get_int(); 30699063Sdes if (nresp != kbdintctxt->nreq) 30799063Sdes fatal("input_userauth_info_response: wrong number of replies"); 30899063Sdes if (nresp > 100) 30999063Sdes fatal("input_userauth_info_response: too many replies"); 31092555Sdes if (nresp > 0) { 311162856Sdes response = xcalloc(nresp, sizeof(char *)); 31292555Sdes for (i = 0; i < nresp; i++) 31392555Sdes response[i] = packet_get_string(NULL); 31492555Sdes } 31592555Sdes packet_check_eom(); 31692555Sdes 317147005Sdes res = kbdintctxt->device->respond(kbdintctxt->ctxt, nresp, response); 31892555Sdes 31992555Sdes for (i = 0; i < nresp; i++) { 320264377Sdes explicit_bzero(response[i], strlen(response[i])); 321255767Sdes free(response[i]); 32292555Sdes } 323255767Sdes free(response); 32492555Sdes 32592555Sdes switch (res) { 32692555Sdes case 0: 32792555Sdes /* Success! */ 328147005Sdes authenticated = authctxt->valid ? 1 : 0; 32992555Sdes break; 33092555Sdes case 1: 33192555Sdes /* Authentication needs further interaction */ 33292555Sdes if (send_userauth_info_request(authctxt) == 1) 33392555Sdes authctxt->postponed = 1; 33492555Sdes break; 33592555Sdes default: 33692555Sdes /* Failure! */ 33792555Sdes break; 33876259Sgreen } 339248619Sdes devicename = kbdintctxt->device->name; 34092555Sdes if (!authctxt->postponed) { 34192555Sdes if (authenticated) { 34292555Sdes auth2_challenge_stop(authctxt); 34392555Sdes } else { 34492555Sdes /* start next device */ 34592555Sdes /* may set authctxt->postponed */ 34692555Sdes auth2_challenge_start(authctxt); 34792555Sdes } 34892555Sdes } 349248619Sdes userauth_finish(authctxt, authenticated, "keyboard-interactive", 350248619Sdes devicename); 35176259Sgreen} 35298684Sdes 35398684Sdesvoid 35498684Sdesprivsep_challenge_enable(void) 35598684Sdes{ 356124211Sdes#if defined(BSD_AUTH) || defined(USE_PAM) || defined(SKEY) 357124211Sdes int n = 0; 358124211Sdes#endif 35998684Sdes#ifdef BSD_AUTH 36098684Sdes extern KbdintDevice mm_bsdauth_device; 36198684Sdes#endif 36299052Sdes#ifdef USE_PAM 363124211Sdes extern KbdintDevice mm_sshpam_device; 36499052Sdes#endif 36598684Sdes#ifdef SKEY 36698684Sdes extern KbdintDevice mm_skey_device; 36798684Sdes#endif 36899052Sdes 36998684Sdes#ifdef BSD_AUTH 37099052Sdes devices[n++] = &mm_bsdauth_device; 37198684Sdes#else 37299052Sdes#ifdef USE_PAM 373124211Sdes devices[n++] = &mm_sshpam_device; 37499052Sdes#endif 37598684Sdes#ifdef SKEY 37699052Sdes devices[n++] = &mm_skey_device; 37798684Sdes#endif 37898684Sdes#endif 37998684Sdes} 380