openssh/auth-krb5.c

   1 /*
   2  *    Kerberos v5 authentication and ticket-passing routines.
   3  *
   4  * $FreeBSD: src/crypto/openssh/auth-krb5.c,v 1.6 2001/02/13 16:58:04 assar Exp $
   5  */
   6 /*
   7  * Copyright (c) 2002 Daniel Kouril.  All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  */
  29
  30 #include "includes.h"
  31 RCSID("$OpenBSD: auth-krb5.c,v 1.10 2002/11/21 23:03:51 deraadt Exp $");
  32
  33 #include "ssh.h"
  34 #include "ssh1.h"
  35 #include "packet.h"
  36 #include "xmalloc.h"
  37 #include "log.h"
  38 #include "servconf.h"
  39 #include "uidswap.h"
  40 #include "auth.h"
  41
  42 #ifdef KRB5
  43 #include <krb5.h>
  44 #ifndef HEIMDAL
  45 #define krb5_get_err_text(context,code) error_message(code)
  46 #endif /* !HEIMDAL */
  47
  48 extern ServerOptions     options;
  49
  50 static int
  51 krb5_init(void *context)
  52 {
  53         Authctxt *authctxt = (Authctxt *)context;
  54         krb5_error_code problem;
  55         static int cleanup_registered = 0;
  56
  57         if (authctxt->krb5_ctx == NULL) {
  58                 problem = krb5_init_context(&authctxt->krb5_ctx);
  59                 if (problem)
  60                         return (problem);
  61                 krb5_init_ets(authctxt->krb5_ctx);
  62         }
  63         if (!cleanup_registered) {
  64                 fatal_add_cleanup(krb5_cleanup_proc, authctxt);
  65                 cleanup_registered = 1;
  66         }
  67         return (0);
  68 }
  69
  70 /*
  71  * Try krb5 authentication. server_user is passed for logging purposes
  72  * only, in auth is received ticket, in client is returned principal
  73  * from the ticket
  74  */
  75 int
  76 auth_krb5(Authctxt *authctxt, krb5_data *auth, char **client, krb5_data *reply)
  77 {
  78         krb5_error_code problem;
  79         krb5_principal server;
  80         krb5_ticket *ticket;
  81         int fd, ret;
  82
  83         ret = 0;
  84         server = NULL;
  85         ticket = NULL;
  86         reply->length = 0;
  87
  88         problem = krb5_init(authctxt);
  89         if (problem)
  90                 goto err;
  91
  92         problem = krb5_auth_con_init(authctxt->krb5_ctx,
  93             &authctxt->krb5_auth_ctx);
  94         if (problem)
  95                 goto err;
  96
  97         fd = packet_get_connection_in();
  98 #ifdef HEIMDAL
  99         problem = krb5_auth_con_setaddrs_from_fd(authctxt->krb5_ctx,
 100             authctxt->krb5_auth_ctx, &fd);
 101 #else
 102         problem = krb5_auth_con_genaddrs(authctxt->krb5_ctx,
 103             authctxt->krb5_auth_ctx,fd,
 104             KRB5_AUTH_CONTEXT_GENERATE_REMOTE_FULL_ADDR |
 105             KRB5_AUTH_CONTEXT_GENERATE_LOCAL_FULL_ADDR);
 106 #endif
 107         if (problem)
 108                 goto err;
 109
 110         problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
 111             KRB5_NT_SRV_HST, &server);
 112         if (problem)
 113                 goto err;
 114
 115         problem = krb5_rd_req(authctxt->krb5_ctx, &authctxt->krb5_auth_ctx,
 116             auth, server, NULL, NULL, &ticket);
 117         if (problem)
 118                 goto err;
 119
 120 #ifdef HEIMDAL
 121         problem = krb5_copy_principal(authctxt->krb5_ctx, ticket->client,
 122             &authctxt->krb5_user);
 123 #else
 124         problem = krb5_copy_principal(authctxt->krb5_ctx,
 125                                       ticket->enc_part2->client,
 126                                       &authctxt->krb5_user);
 127 #endif
 128         if (problem)
 129                 goto err;
 130
 131         /* if client wants mutual auth */
 132         problem = krb5_mk_rep(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
 133             reply);
 134         if (problem)
 135                 goto err;
 136
 137         /* Check .k5login authorization now. */
 138         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 139             authctxt->pw->pw_name))
 140                 goto err;
 141
 142         if (client)
 143                 krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
 144                     client);
 145
 146         ret = 1;
 147  err:
 148         if (server)
 149                 krb5_free_principal(authctxt->krb5_ctx, server);
 150         if (ticket)
 151                 krb5_free_ticket(authctxt->krb5_ctx, ticket);
 152         if (!ret && reply->length) {
 153                 xfree(reply->data);
 154                 memset(reply, 0, sizeof(*reply));
 155         }
 156
 157         if (problem) {
 158                 if (authctxt->krb5_ctx != NULL)
 159                         debug("Kerberos v5 authentication failed: %s",
 160                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 161                 else
 162                         debug("Kerberos v5 authentication failed: %d",
 163                             problem);
 164         }
 165
 166         return (ret);
 167 }
 168
 169 int
 170 auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt)
 171 {
 172         krb5_error_code problem;
 173         krb5_ccache ccache = NULL;
 174         char *pname;
 175         krb5_creds **creds;
 176
 177         if (authctxt->pw == NULL || authctxt->krb5_user == NULL)
 178                 return (0);
 179
 180         temporarily_use_uid(authctxt->pw);
 181
 182 #ifdef HEIMDAL
 183         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops, &ccache);
 184 #else
 185 {
 186         char ccname[40];
 187         int tmpfd;
 188
 189         snprintf(ccname,sizeof(ccname),"FILE:/tmp/krb5cc_%d_XXXXXX",geteuid());
 190
 191         if ((tmpfd = mkstemp(ccname+strlen("FILE:")))==-1) {
 192                 log("mkstemp(): %.100s", strerror(errno));
 193                 problem = errno;
 194                 goto fail;
 195         }
 196         if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
 197                 log("fchmod(): %.100s", strerror(errno));
 198                 close(tmpfd);
 199                 problem = errno;
 200                 goto fail;
 201         }
 202         close(tmpfd);
 203         problem = krb5_cc_resolve(authctxt->krb5_ctx, ccname, &ccache);
 204 }
 205 #endif
 206         if (problem)
 207                 goto fail;
 208
 209         problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
 210             authctxt->krb5_user);
 211         if (problem)
 212                 goto fail;
 213
 214 #ifdef HEIMDAL
 215         problem = krb5_rd_cred2(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
 216             ccache, tgt);
 217         if (problem)
 218                 goto fail;
 219 #else
 220         problem = krb5_rd_cred(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
 221             tgt, &creds, NULL);
 222         if (problem)
 223                 goto fail;
 224         problem = krb5_cc_store_cred(authctxt->krb5_ctx, ccache, *creds);
 225         if (problem)
 226                 goto fail;
 227 #endif
 228
 229         authctxt->krb5_fwd_ccache = ccache;
 230         ccache = NULL;
 231
 232         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 233
 234         problem = krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
 235             &pname);
 236         if (problem)
 237                 goto fail;
 238
 239         debug("Kerberos v5 TGT accepted (%s)", pname);
 240
 241         restore_uid();
 242
 243         return (1);
 244
 245  fail:
 246         if (problem)
 247                 debug("Kerberos v5 TGT passing failed: %s",
 248                     krb5_get_err_text(authctxt->krb5_ctx, problem));
 249         if (ccache)
 250                 krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 251
 252         restore_uid();
 253
 254         return (0);
 255 }
 256
 257 int
 258 auth_krb5_password(Authctxt *authctxt, const char *password)
 259 {
 260 #ifndef HEIMDAL
 261         krb5_creds creds;
 262         krb5_principal server;
 263         char ccname[40];
 264         int tmpfd;
 265 #endif
 266         krb5_error_code problem;
 267
 268         if (authctxt->pw == NULL)
 269                 return (0);
 270
 271         temporarily_use_uid(authctxt->pw);
 272
 273         problem = krb5_init(authctxt);
 274         if (problem)
 275                 goto out;
 276
 277         problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
 278                     &authctxt->krb5_user);
 279         if (problem)
 280                 goto out;
 281
 282 #ifdef HEIMDAL
 283         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops,
 284             &authctxt->krb5_fwd_ccache);
 285         if (problem)
 286                 goto out;
 287
 288         problem = krb5_cc_initialize(authctxt->krb5_ctx,
 289             authctxt->krb5_fwd_ccache, authctxt->krb5_user);
 290         if (problem)
 291                 goto out;
 292
 293         restore_uid();
 294         problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
 295             authctxt->krb5_fwd_ccache, password, 1, NULL);
 296         temporarily_use_uid(authctxt->pw);
 297
 298         if (problem)
 299                 goto out;
 300
 301 #else
 302         problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
 303             authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
 304         if (problem)
 305                 goto out;
 306
 307         problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
 308             KRB5_NT_SRV_HST, &server);
 309         if (problem)
 310                 goto out;
 311
 312         restore_uid();
 313         problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
 314             NULL, NULL, NULL);
 315         krb5_free_principal(authctxt->krb5_ctx, server);
 316         temporarily_use_uid(authctxt->pw);
 317         if (problem)
 318                 goto out;
 319
 320         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 321                           authctxt->pw->pw_name)) {
 322                 problem = -1;
 323                 goto out;
 324         }
 325
 326         snprintf(ccname,sizeof(ccname),"FILE:/tmp/krb5cc_%d_XXXXXX",geteuid());
 327
 328         if ((tmpfd = mkstemp(ccname+strlen("FILE:")))==-1) {
 329                 log("mkstemp(): %.100s", strerror(errno));
 330                 problem = errno;
 331                 goto out;
 332         }
 333
 334         if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
 335                 log("fchmod(): %.100s", strerror(errno));
 336                 close(tmpfd);
 337                 problem = errno;
 338                 goto out;
 339         }
 340         close(tmpfd);
 341
 342         problem = krb5_cc_resolve(authctxt->krb5_ctx, ccname, &authctxt->krb5_fwd_ccache);
 343         if (problem)
 344                 goto out;
 345
 346         problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 347                                      authctxt->krb5_user);
 348         if (problem)
 349                 goto out;
 350
 351         problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 352                                  &creds);
 353         if (problem)
 354                 goto out;
 355 #endif
 356
 357         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 358
 359  out:
 360         restore_uid();
 361
 362         if (problem) {
 363                 if (authctxt->krb5_ctx != NULL && problem!=-1)
 364                         debug("Kerberos password authentication failed: %s",
 365                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 366                 else
 367                         debug("Kerberos password authentication failed: %d",
 368                             problem);
 369
 370                 krb5_cleanup_proc(authctxt);
 371
 372                 if (options.kerberos_or_local_passwd)
 373                         return (-1);
 374                 else
 375                         return (0);
 376         }
 377         return (1);
 378 }
 379
 380 void
 381 krb5_cleanup_proc(void *context)
 382 {
 383         Authctxt *authctxt = (Authctxt *)context;
 384
 385         debug("krb5_cleanup_proc called");
 386         if (authctxt->krb5_fwd_ccache) {
 387                 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 388                 authctxt->krb5_fwd_ccache = NULL;
 389         }
 390         if (authctxt->krb5_user) {
 391                 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
 392                 authctxt->krb5_user = NULL;
 393         }
 394         if (authctxt->krb5_auth_ctx) {
 395                 krb5_auth_con_free(authctxt->krb5_ctx,
 396                     authctxt->krb5_auth_ctx);
 397                 authctxt->krb5_auth_ctx = NULL;
 398         }
 399         if (authctxt->krb5_ctx) {
 400                 krb5_free_context(authctxt->krb5_ctx);
 401                 authctxt->krb5_ctx = NULL;
 402         }
 403 }
 404
 405 #endif /* KRB5 */