crypto/openssh/auth-krb5.c

   1 /*
   2  *    Kerberos v5 authentication and ticket-passing routines.
   3  *
   4  * $xFreeBSD: src/crypto/openssh/auth-krb5.c,v 1.6 2001/02/13 16:58:04 assar Exp$
   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 1.9 2002/09/09 06:48:06 itojun Exp $");
  32 RCSID("$FreeBSD: src/crypto/openssh/auth-krb5.c,v 1.2.2.6 2003/02/03 17:31:06 des Exp $");
  33 RCSID("$DragonFly: src/crypto/openssh/Attic/auth-krb5.c,v 1.2 2003/06/17 04:24:36 dillon Exp $");
  34
  35 #include "ssh.h"
  36 #include "ssh1.h"
  37 #include "packet.h"
  38 #include "xmalloc.h"
  39 #include "log.h"
  40 #include "servconf.h"
  41 #include "uidswap.h"
  42 #include "auth.h"
  43
  44 #ifdef KRB5
  45 #include <krb5.h>
  46 #ifndef HEIMDAL
  47 #define krb5_get_err_text(context,code) error_message(code)
  48 #endif /* !HEIMDAL */
  49
  50 extern ServerOptions     options;
  51
  52 static int
  53 krb5_init(void *context)
  54 {
  55         Authctxt *authctxt = (Authctxt *)context;
  56         krb5_error_code problem;
  57         static int cleanup_registered = 0;
  58
  59         if (authctxt->krb5_ctx == NULL) {
  60                 problem = krb5_init_context(&authctxt->krb5_ctx);
  61                 if (problem)
  62                         return (problem);
  63                 krb5_init_ets(authctxt->krb5_ctx);
  64         }
  65         if (!cleanup_registered) {
  66                 fatal_add_cleanup(krb5_cleanup_proc, authctxt);
  67                 cleanup_registered = 1;
  68         }
  69         return (0);
  70 }
  71
  72 /*
  73  * Try krb5 authentication. server_user is passed for logging purposes
  74  * only, in auth is received ticket, in client is returned principal
  75  * from the ticket
  76  */
  77 int
  78 auth_krb5(Authctxt *authctxt, krb5_data *auth, char **client, krb5_data *reply)
  79 {
  80         krb5_error_code problem;
  81         krb5_principal server;
  82         krb5_ticket *ticket;
  83         int fd, ret;
  84
  85         ret = 0;
  86         server = NULL;
  87         ticket = NULL;
  88         reply->length = 0;
  89
  90         problem = krb5_init(authctxt);
  91         if (problem)
  92                 goto err;
  93
  94         problem = krb5_auth_con_init(authctxt->krb5_ctx,
  95             &authctxt->krb5_auth_ctx);
  96         if (problem)
  97                 goto err;
  98
  99         fd = packet_get_connection_in();
 100 #ifdef HEIMDAL
 101         problem = krb5_auth_con_setaddrs_from_fd(authctxt->krb5_ctx,
 102             authctxt->krb5_auth_ctx, &fd);
 103 #else
 104         problem = krb5_auth_con_genaddrs(authctxt->krb5_ctx,
 105             authctxt->krb5_auth_ctx,fd,
 106             KRB5_AUTH_CONTEXT_GENERATE_REMOTE_FULL_ADDR |
 107             KRB5_AUTH_CONTEXT_GENERATE_LOCAL_FULL_ADDR);
 108 #endif
 109         if (problem)
 110                 goto err;
 111
 112         problem = krb5_sname_to_principal(authctxt->krb5_ctx,  NULL, NULL ,
 113             KRB5_NT_SRV_HST, &server);
 114         if (problem)
 115                 goto err;
 116
 117         problem = krb5_rd_req(authctxt->krb5_ctx, &authctxt->krb5_auth_ctx,
 118             auth, server, NULL, NULL, &ticket);
 119         if (problem)
 120                 goto err;
 121
 122 #ifdef HEIMDAL
 123         problem = krb5_copy_principal(authctxt->krb5_ctx, ticket->client,
 124             &authctxt->krb5_user);
 125 #else
 126         problem = krb5_copy_principal(authctxt->krb5_ctx,
 127                                       ticket->enc_part2->client,
 128                                       &authctxt->krb5_user);
 129 #endif
 130         if (problem)
 131                 goto err;
 132
 133         /* if client wants mutual auth */
 134         problem = krb5_mk_rep(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
 135             reply);
 136         if (problem)
 137                 goto err;
 138
 139         /* Check .k5login authorization now. */
 140         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 141             authctxt->pw->pw_name))
 142                 goto err;
 143
 144         if (client)
 145                 krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
 146                     client);
 147
 148         ret = 1;
 149  err:
 150         if (server)
 151                 krb5_free_principal(authctxt->krb5_ctx, server);
 152         if (ticket)
 153                 krb5_free_ticket(authctxt->krb5_ctx, ticket);
 154         if (!ret && reply->length) {
 155                 xfree(reply->data);
 156                 memset(reply, 0, sizeof(*reply));
 157         }
 158
 159         if (problem) {
 160                 if (authctxt->krb5_ctx != NULL)
 161                         debug("Kerberos v5 authentication failed: %s",
 162                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 163                 else
 164                         debug("Kerberos v5 authentication failed: %d",
 165                             problem);
 166         }
 167
 168         return (ret);
 169 }
 170
 171 int
 172 auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt)
 173 {
 174         krb5_error_code problem;
 175         krb5_ccache ccache = NULL;
 176         char *pname;
 177         krb5_creds **creds;
 178
 179         if (authctxt->pw == NULL || authctxt->krb5_user == NULL)
 180                 return (0);
 181
 182         temporarily_use_uid(authctxt->pw);
 183
 184 #ifdef HEIMDAL
 185         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops, &ccache);
 186 #else
 187 {
 188         char ccname[40];
 189         int tmpfd;
 190
 191         snprintf(ccname,sizeof(ccname),"FILE:/tmp/krb5cc_%d_XXXXXX",geteuid());
 192
 193         if ((tmpfd = mkstemp(ccname+strlen("FILE:")))==-1) {
 194                 log("mkstemp(): %.100s", strerror(errno));
 195                 problem = errno;
 196                 goto fail;
 197         }
 198         if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
 199                 log("fchmod(): %.100s", strerror(errno));
 200                 close(tmpfd);
 201                 problem = errno;
 202                 goto fail;
 203         }
 204         close(tmpfd);
 205         problem = krb5_cc_resolve(authctxt->krb5_ctx, ccname, &ccache);
 206 }
 207 #endif
 208         if (problem)
 209                 goto fail;
 210
 211         problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
 212             authctxt->krb5_user);
 213         if (problem)
 214                 goto fail;
 215
 216 #ifdef HEIMDAL
 217         problem = krb5_rd_cred2(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
 218             ccache, tgt);
 219         if (problem)
 220                 goto fail;
 221 #else
 222         problem = krb5_rd_cred(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
 223             tgt, &creds, NULL);
 224         if (problem)
 225                 goto fail;
 226         problem = krb5_cc_store_cred(authctxt->krb5_ctx, ccache, *creds);
 227         if (problem)
 228                 goto fail;
 229 #endif
 230
 231         authctxt->krb5_fwd_ccache = ccache;
 232         ccache = NULL;
 233
 234         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 235
 236         problem = krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
 237             &pname);
 238         if (problem)
 239                 goto fail;
 240
 241         debug("Kerberos v5 TGT accepted (%s)", pname);
 242
 243         restore_uid();
 244
 245         return (1);
 246
 247  fail:
 248         if (problem)
 249                 debug("Kerberos v5 TGT passing failed: %s",
 250                     krb5_get_err_text(authctxt->krb5_ctx, problem));
 251         if (ccache)
 252                 krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 253
 254         restore_uid();
 255
 256         return (0);
 257 }
 258
 259 int
 260 auth_krb5_password(Authctxt *authctxt, const char *password)
 261 {
 262 #ifndef HEIMDAL
 263         krb5_creds creds;
 264         krb5_principal server;
 265         char ccname[40];
 266         int tmpfd;
 267 #endif
 268         krb5_error_code problem;
 269
 270         if (authctxt->pw == NULL)
 271                 return (0);
 272
 273         temporarily_use_uid(authctxt->pw);
 274
 275         problem = krb5_init(authctxt);
 276         if (problem)
 277                 goto out;
 278
 279         problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
 280                     &authctxt->krb5_user);
 281         if (problem)
 282                 goto out;
 283
 284 #ifdef HEIMDAL
 285         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops,
 286             &authctxt->krb5_fwd_ccache);
 287         if (problem)
 288                 goto out;
 289
 290         problem = krb5_cc_initialize(authctxt->krb5_ctx,
 291             authctxt->krb5_fwd_ccache, authctxt->krb5_user);
 292         if (problem)
 293                 goto out;
 294
 295         restore_uid();
 296         problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
 297             authctxt->krb5_fwd_ccache, password, 1, NULL);
 298         temporarily_use_uid(authctxt->pw);
 299
 300         if (problem)
 301                 goto out;
 302
 303 #else
 304         problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
 305             authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
 306         if (problem)
 307                 goto out;
 308
 309         problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
 310             KRB5_NT_SRV_HST, &server);
 311         if (problem)
 312                 goto out;
 313
 314         restore_uid();
 315         problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
 316             NULL, NULL, NULL);
 317         krb5_free_principal(authctxt->krb5_ctx, server);
 318         temporarily_use_uid(authctxt->pw);
 319         if (problem)
 320                 goto out;
 321
 322         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 323                           authctxt->pw->pw_name)) {
 324                 problem = -1;
 325                 goto out;
 326         }
 327
 328         snprintf(ccname,sizeof(ccname),"FILE:/tmp/krb5cc_%d_XXXXXX",geteuid());
 329
 330         if ((tmpfd = mkstemp(ccname+strlen("FILE:")))==-1) {
 331                 log("mkstemp(): %.100s", strerror(errno));
 332                 problem = errno;
 333                 goto out;
 334         }
 335
 336         if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
 337                 log("fchmod(): %.100s", strerror(errno));
 338                 close(tmpfd);
 339                 problem = errno;
 340                 goto out;
 341         }
 342         close(tmpfd);
 343
 344         problem = krb5_cc_resolve(authctxt->krb5_ctx, ccname, &authctxt->krb5_fwd_ccache);
 345         if (problem)
 346                 goto out;
 347
 348         problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 349                                      authctxt->krb5_user);
 350         if (problem)
 351                 goto out;
 352
 353         problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 354                                  &creds);
 355         if (problem)
 356                 goto out;
 357 #endif
 358
 359         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 360
 361  out:
 362         restore_uid();
 363
 364         if (problem) {
 365                 if (authctxt->krb5_ctx != NULL && problem!=-1)
 366                         debug("Kerberos password authentication failed: %s",
 367                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 368                 else
 369                         debug("Kerberos password authentication failed: %d",
 370                             problem);
 371
 372                 krb5_cleanup_proc(authctxt);
 373
 374                 if (options.kerberos_or_local_passwd)
 375                         return (-1);
 376                 else
 377                         return (0);
 378         }
 379         return (1);
 380 }
 381
 382 void
 383 krb5_cleanup_proc(void *context)
 384 {
 385         Authctxt *authctxt = (Authctxt *)context;
 386
 387         debug("krb5_cleanup_proc called");
 388         if (authctxt->krb5_fwd_ccache) {
 389                 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 390                 authctxt->krb5_fwd_ccache = NULL;
 391         }
 392         if (authctxt->krb5_user) {
 393                 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
 394                 authctxt->krb5_user = NULL;
 395         }
 396         if (authctxt->krb5_auth_ctx) {
 397                 krb5_auth_con_free(authctxt->krb5_ctx,
 398                     authctxt->krb5_auth_ctx);
 399                 authctxt->krb5_auth_ctx = NULL;
 400         }
 401         if (authctxt->krb5_ctx) {
 402                 krb5_free_context(authctxt->krb5_ctx);
 403                 authctxt->krb5_ctx = NULL;
 404         }
 405 }
 406
 407 #endif /* KRB5 */