| /* $OpenBSD: auth2-chall.c,v 1.30 2006/08/03 03:34:41 deraadt 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 <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 |
| } |