auth2-chall.c revision 181111
1181111Sdes/* $OpenBSD: auth2-chall.c,v 1.33 2007/09/21 08:15:29 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; 8592555Sdes}; 8692555Sdes 87147005Sdes#ifdef USE_PAM 88147005Sdesvoid 89147005Sdesremove_kbdint_device(const char *devname) 90147005Sdes{ 91147005Sdes int i, j; 92147005Sdes 93147005Sdes for (i = 0; devices[i] != NULL; i++) 94147005Sdes if (strcmp(devices[i]->name, devname) == 0) { 95147005Sdes for (j = i; devices[j] != NULL; j++) 96147005Sdes devices[j] = devices[j+1]; 97147005Sdes i--; 98147005Sdes } 99147005Sdes} 100147005Sdes#endif 101147005Sdes 10292555Sdesstatic KbdintAuthctxt * 10392555Sdeskbdint_alloc(const char *devs) 10492555Sdes{ 10592555Sdes KbdintAuthctxt *kbdintctxt; 10692555Sdes Buffer b; 10792555Sdes int i; 10892555Sdes 109147005Sdes#ifdef USE_PAM 110147005Sdes if (!options.use_pam) 111147005Sdes remove_kbdint_device("pam"); 112147005Sdes#endif 113147005Sdes 11492555Sdes kbdintctxt = xmalloc(sizeof(KbdintAuthctxt)); 11592555Sdes if (strcmp(devs, "") == 0) { 11692555Sdes buffer_init(&b); 11792555Sdes for (i = 0; devices[i]; i++) { 11892555Sdes if (buffer_len(&b) > 0) 11992555Sdes buffer_append(&b, ",", 1); 12092555Sdes buffer_append(&b, devices[i]->name, 12192555Sdes strlen(devices[i]->name)); 12292555Sdes } 12392555Sdes buffer_append(&b, "\0", 1); 12492555Sdes kbdintctxt->devices = xstrdup(buffer_ptr(&b)); 12592555Sdes buffer_free(&b); 12692555Sdes } else { 12792555Sdes kbdintctxt->devices = xstrdup(devs); 12892555Sdes } 12992555Sdes debug("kbdint_alloc: devices '%s'", kbdintctxt->devices); 13092555Sdes kbdintctxt->ctxt = NULL; 13192555Sdes kbdintctxt->device = NULL; 13299063Sdes kbdintctxt->nreq = 0; 13392555Sdes 13492555Sdes return kbdintctxt; 13592555Sdes} 13692555Sdesstatic void 13792555Sdeskbdint_reset_device(KbdintAuthctxt *kbdintctxt) 13892555Sdes{ 13992555Sdes if (kbdintctxt->ctxt) { 14092555Sdes kbdintctxt->device->free_ctx(kbdintctxt->ctxt); 14192555Sdes kbdintctxt->ctxt = NULL; 14292555Sdes } 14392555Sdes kbdintctxt->device = NULL; 14492555Sdes} 14592555Sdesstatic void 14692555Sdeskbdint_free(KbdintAuthctxt *kbdintctxt) 14792555Sdes{ 14892555Sdes if (kbdintctxt->device) 14992555Sdes kbdint_reset_device(kbdintctxt); 15092555Sdes if (kbdintctxt->devices) { 15192555Sdes xfree(kbdintctxt->devices); 15292555Sdes kbdintctxt->devices = NULL; 15392555Sdes } 15492555Sdes xfree(kbdintctxt); 15592555Sdes} 15692555Sdes/* get next device */ 15792555Sdesstatic int 15892555Sdeskbdint_next_device(KbdintAuthctxt *kbdintctxt) 15992555Sdes{ 16092555Sdes size_t len; 16192555Sdes char *t; 16292555Sdes int i; 16392555Sdes 16492555Sdes if (kbdintctxt->device) 16592555Sdes kbdint_reset_device(kbdintctxt); 16692555Sdes do { 16792555Sdes len = kbdintctxt->devices ? 16892555Sdes strcspn(kbdintctxt->devices, ",") : 0; 16992555Sdes 17092555Sdes if (len == 0) 17192555Sdes break; 17292555Sdes for (i = 0; devices[i]; i++) 17392555Sdes if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0) 17492555Sdes kbdintctxt->device = devices[i]; 17592555Sdes t = kbdintctxt->devices; 17692555Sdes kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL; 17792555Sdes xfree(t); 17892555Sdes debug2("kbdint_next_device: devices %s", kbdintctxt->devices ? 179149753Sdes kbdintctxt->devices : "<empty>"); 18092555Sdes } while (kbdintctxt->devices && !kbdintctxt->device); 18192555Sdes 18292555Sdes return kbdintctxt->device ? 1 : 0; 18392555Sdes} 18492555Sdes 18576259Sgreen/* 18692555Sdes * try challenge-response, set authctxt->postponed if we have to 18776259Sgreen * wait for the response. 18876259Sgreen */ 18976259Sgreenint 19076259Sgreenauth2_challenge(Authctxt *authctxt, char *devs) 19176259Sgreen{ 19292555Sdes debug("auth2_challenge: user=%s devs=%s", 19392555Sdes authctxt->user ? authctxt->user : "<nouser>", 19492555Sdes devs ? devs : "<no devs>"); 19576259Sgreen 19692555Sdes if (authctxt->user == NULL || !devs) 19776259Sgreen return 0; 19892555Sdes if (authctxt->kbdintctxt == NULL) 19992555Sdes authctxt->kbdintctxt = kbdint_alloc(devs); 20092555Sdes return auth2_challenge_start(authctxt); 20192555Sdes} 20292555Sdes 20392555Sdes/* unregister kbd-int callbacks and context */ 20492555Sdesvoid 20592555Sdesauth2_challenge_stop(Authctxt *authctxt) 20692555Sdes{ 20792555Sdes /* unregister callback */ 20892555Sdes dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL); 209181111Sdes if (authctxt->kbdintctxt != NULL) { 21092555Sdes kbdint_free(authctxt->kbdintctxt); 21192555Sdes authctxt->kbdintctxt = NULL; 21292555Sdes } 21392555Sdes} 21492555Sdes 21592555Sdes/* side effect: sets authctxt->postponed if a reply was sent*/ 21692555Sdesstatic int 21792555Sdesauth2_challenge_start(Authctxt *authctxt) 21892555Sdes{ 21992555Sdes KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt; 22092555Sdes 22192555Sdes debug2("auth2_challenge_start: devices %s", 22292555Sdes kbdintctxt->devices ? kbdintctxt->devices : "<empty>"); 22392555Sdes 22492555Sdes if (kbdint_next_device(kbdintctxt) == 0) { 22592555Sdes auth2_challenge_stop(authctxt); 22676259Sgreen return 0; 22792555Sdes } 22892555Sdes debug("auth2_challenge_start: trying authentication method '%s'", 22992555Sdes kbdintctxt->device->name); 23092555Sdes 23192555Sdes if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) { 23292555Sdes auth2_challenge_stop(authctxt); 23392555Sdes return 0; 23492555Sdes } 23592555Sdes if (send_userauth_info_request(authctxt) == 0) { 23692555Sdes auth2_challenge_stop(authctxt); 23792555Sdes return 0; 23892555Sdes } 23976259Sgreen dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, 24076259Sgreen &input_userauth_info_response); 24192555Sdes 24276259Sgreen authctxt->postponed = 1; 24376259Sgreen return 0; 24476259Sgreen} 24576259Sgreen 24692555Sdesstatic int 24792555Sdessend_userauth_info_request(Authctxt *authctxt) 24876259Sgreen{ 24992555Sdes KbdintAuthctxt *kbdintctxt; 25092555Sdes char *name, *instr, **prompts; 251149753Sdes u_int i, *echo_on; 25276259Sgreen 25392555Sdes kbdintctxt = authctxt->kbdintctxt; 25492555Sdes if (kbdintctxt->device->query(kbdintctxt->ctxt, 25599063Sdes &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on)) 25692555Sdes return 0; 25792555Sdes 25876259Sgreen packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST); 25992555Sdes packet_put_cstring(name); 26092555Sdes packet_put_cstring(instr); 26198684Sdes packet_put_cstring(""); /* language not used */ 26299063Sdes packet_put_int(kbdintctxt->nreq); 26399063Sdes for (i = 0; i < kbdintctxt->nreq; i++) { 26492555Sdes packet_put_cstring(prompts[i]); 26592555Sdes packet_put_char(echo_on[i]); 26692555Sdes } 26776259Sgreen packet_send(); 26876259Sgreen packet_write_wait(); 26992555Sdes 27099063Sdes for (i = 0; i < kbdintctxt->nreq; i++) 27192555Sdes xfree(prompts[i]); 27292555Sdes xfree(prompts); 27392555Sdes xfree(echo_on); 27492555Sdes xfree(name); 27592555Sdes xfree(instr); 27692555Sdes return 1; 27776259Sgreen} 27876259Sgreen 27992555Sdesstatic void 28092555Sdesinput_userauth_info_response(int type, u_int32_t seq, void *ctxt) 28176259Sgreen{ 28276259Sgreen Authctxt *authctxt = ctxt; 28392555Sdes KbdintAuthctxt *kbdintctxt; 284149753Sdes int authenticated = 0, res, len; 285149753Sdes u_int i, nresp; 28692555Sdes char **response = NULL, *method; 28776259Sgreen 28876259Sgreen if (authctxt == NULL) 28976259Sgreen fatal("input_userauth_info_response: no authctxt"); 29092555Sdes kbdintctxt = authctxt->kbdintctxt; 29192555Sdes if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL) 29292555Sdes fatal("input_userauth_info_response: no kbdintctxt"); 29392555Sdes if (kbdintctxt->device == NULL) 29492555Sdes fatal("input_userauth_info_response: no device"); 29576259Sgreen 29676259Sgreen authctxt->postponed = 0; /* reset */ 29776259Sgreen nresp = packet_get_int(); 29899063Sdes if (nresp != kbdintctxt->nreq) 29999063Sdes fatal("input_userauth_info_response: wrong number of replies"); 30099063Sdes if (nresp > 100) 30199063Sdes fatal("input_userauth_info_response: too many replies"); 30292555Sdes if (nresp > 0) { 303162856Sdes response = xcalloc(nresp, sizeof(char *)); 30492555Sdes for (i = 0; i < nresp; i++) 30592555Sdes response[i] = packet_get_string(NULL); 30692555Sdes } 30792555Sdes packet_check_eom(); 30892555Sdes 309147005Sdes res = kbdintctxt->device->respond(kbdintctxt->ctxt, nresp, response); 31092555Sdes 31192555Sdes for (i = 0; i < nresp; i++) { 31292555Sdes memset(response[i], 'r', strlen(response[i])); 31392555Sdes xfree(response[i]); 31492555Sdes } 31592555Sdes if (response) 31676259Sgreen xfree(response); 31792555Sdes 31892555Sdes switch (res) { 31992555Sdes case 0: 32092555Sdes /* Success! */ 321147005Sdes authenticated = authctxt->valid ? 1 : 0; 32292555Sdes break; 32392555Sdes case 1: 32492555Sdes /* Authentication needs further interaction */ 32592555Sdes if (send_userauth_info_request(authctxt) == 1) 32692555Sdes authctxt->postponed = 1; 32792555Sdes break; 32892555Sdes default: 32992555Sdes /* Failure! */ 33092555Sdes break; 33176259Sgreen } 33276259Sgreen 33392555Sdes len = strlen("keyboard-interactive") + 2 + 33492555Sdes strlen(kbdintctxt->device->name); 33592555Sdes method = xmalloc(len); 33692555Sdes snprintf(method, len, "keyboard-interactive/%s", 33792555Sdes kbdintctxt->device->name); 33892555Sdes 33992555Sdes if (!authctxt->postponed) { 34092555Sdes if (authenticated) { 34192555Sdes auth2_challenge_stop(authctxt); 34292555Sdes } else { 34392555Sdes /* start next device */ 34492555Sdes /* may set authctxt->postponed */ 34592555Sdes auth2_challenge_start(authctxt); 34692555Sdes } 34792555Sdes } 34876259Sgreen userauth_finish(authctxt, authenticated, method); 34992555Sdes xfree(method); 35076259Sgreen} 35198684Sdes 35298684Sdesvoid 35398684Sdesprivsep_challenge_enable(void) 35498684Sdes{ 355124211Sdes#if defined(BSD_AUTH) || defined(USE_PAM) || defined(SKEY) 356124211Sdes int n = 0; 357124211Sdes#endif 35898684Sdes#ifdef BSD_AUTH 35998684Sdes extern KbdintDevice mm_bsdauth_device; 36098684Sdes#endif 36199052Sdes#ifdef USE_PAM 362124211Sdes extern KbdintDevice mm_sshpam_device; 36399052Sdes#endif 36498684Sdes#ifdef SKEY 36598684Sdes extern KbdintDevice mm_skey_device; 36698684Sdes#endif 36799052Sdes 36898684Sdes#ifdef BSD_AUTH 36999052Sdes devices[n++] = &mm_bsdauth_device; 37098684Sdes#else 37199052Sdes#ifdef USE_PAM 372124211Sdes devices[n++] = &mm_sshpam_device; 37399052Sdes#endif 37498684Sdes#ifdef SKEY 37599052Sdes devices[n++] = &mm_skey_device; 37698684Sdes#endif 37798684Sdes#endif 37898684Sdes} 379