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