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 1.8 2002/03/19 10:49:35 markus 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)
  77 {
  78         krb5_error_code problem;
  79         krb5_principal server;
  80         krb5_data reply;
  81         krb5_ticket *ticket;
  82         int fd, ret;
  83
  84         ret = 0;
  85         server = NULL;
  86         ticket = NULL;
  87         reply.length = 0;
  88
  89         problem = krb5_init(authctxt);
  90         if (problem)
  91                 goto err;
  92
  93         problem = krb5_auth_con_init(authctxt->krb5_ctx,
  94             &authctxt->krb5_auth_ctx);
  95         if (problem)
  96                 goto err;
  97
  98         fd = packet_get_connection_in();
  99 #ifdef HEIMDAL
 100         problem = krb5_auth_con_setaddrs_from_fd(authctxt->krb5_ctx,
 101             authctxt->krb5_auth_ctx, &fd);
 102 #else
 103         problem = krb5_auth_con_genaddrs(authctxt->krb5_ctx,
 104             authctxt->krb5_auth_ctx,fd,
 105             KRB5_AUTH_CONTEXT_GENERATE_REMOTE_FULL_ADDR |
 106             KRB5_AUTH_CONTEXT_GENERATE_LOCAL_FULL_ADDR);
 107 #endif
 108         if (problem)
 109                 goto err;
 110
 111         problem = krb5_sname_to_principal(authctxt->krb5_ctx,  NULL, NULL ,
 112             KRB5_NT_SRV_HST, &server);
 113         if (problem)
 114                 goto err;
 115
 116         problem = krb5_rd_req(authctxt->krb5_ctx, &authctxt->krb5_auth_ctx,
 117             auth, server, NULL, NULL, &ticket);
 118         if (problem)
 119                 goto err;
 120
 121 #ifdef HEIMDAL
 122         problem = krb5_copy_principal(authctxt->krb5_ctx, ticket->client,
 123             &authctxt->krb5_user);
 124 #else
 125         problem = krb5_copy_principal(authctxt->krb5_ctx,
 126                                       ticket->enc_part2->client,
 127                                       &authctxt->krb5_user);
 128 #endif
 129         if (problem)
 130                 goto err;
 131
 132         /* if client wants mutual auth */
 133         problem = krb5_mk_rep(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
 134             &reply);
 135         if (problem)
 136                 goto err;
 137
 138         /* Check .k5login authorization now. */
 139         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 140             authctxt->pw->pw_name))
 141                 goto err;
 142
 143         if (client)
 144                 krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
 145                     client);
 146
 147         packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
 148         packet_put_string((char *) reply.data, reply.length);
 149         packet_send();
 150         packet_write_wait();
 151
 152         ret = 1;
 153  err:
 154         if (server)
 155                 krb5_free_principal(authctxt->krb5_ctx, server);
 156         if (ticket)
 157                 krb5_free_ticket(authctxt->krb5_ctx, ticket);
 158         if (reply.length)
 159                 xfree(reply.data);
 160
 161         if (problem) {
 162                 if (authctxt->krb5_ctx != NULL)
 163                         debug("Kerberos v5 authentication failed: %s",
 164                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 165                 else
 166                         debug("Kerberos v5 authentication failed: %d",
 167                             problem);
 168         }
 169
 170         return (ret);
 171 }
 172
 173 int
 174 auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt)
 175 {
 176         krb5_error_code problem;
 177         krb5_ccache ccache = NULL;
 178         char *pname;
 179         krb5_creds **creds;
 180
 181         if (authctxt->pw == NULL || authctxt->krb5_user == NULL)
 182                 return (0);
 183
 184         temporarily_use_uid(authctxt->pw);
 185
 186 #ifdef HEIMDAL
 187         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops, &ccache);
 188 #else
 189 {
 190         char ccname[40];
 191         int tmpfd;
 192
 193         snprintf(ccname,sizeof(ccname),"FILE:/tmp/krb5cc_%d_XXXXXX",geteuid());
 194
 195         if ((tmpfd = mkstemp(ccname+strlen("FILE:")))==-1) {
 196                 log("mkstemp(): %.100s", strerror(errno));
 197                 problem = errno;
 198                 goto fail;
 199         }
 200         if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
 201                 log("fchmod(): %.100s", strerror(errno));
 202                 close(tmpfd);
 203                 problem = errno;
 204                 goto fail;
 205         }
 206         close(tmpfd);
 207         problem = krb5_cc_resolve(authctxt->krb5_ctx, ccname, &ccache);
 208 }
 209 #endif
 210         if (problem)
 211                 goto fail;
 212
 213         problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
 214             authctxt->krb5_user);
 215         if (problem)
 216                 goto fail;
 217
 218 #ifdef HEIMDAL
 219         problem = krb5_rd_cred2(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
 220             ccache, tgt);
 221         if (problem)
 222                 goto fail;
 223 #else
 224         problem = krb5_rd_cred(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
 225             tgt, &creds, NULL);
 226         if (problem)
 227                 goto fail;
 228         problem = krb5_cc_store_cred(authctxt->krb5_ctx, ccache, *creds);
 229         if (problem)
 230                 goto fail;
 231 #endif
 232
 233         authctxt->krb5_fwd_ccache = ccache;
 234         ccache = NULL;
 235
 236         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 237
 238         problem = krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
 239             &pname);
 240         if (problem)
 241                 goto fail;
 242
 243         debug("Kerberos v5 TGT accepted (%s)", pname);
 244
 245         restore_uid();
 246
 247         return (1);
 248
 249  fail:
 250         if (problem)
 251                 debug("Kerberos v5 TGT passing failed: %s",
 252                     krb5_get_err_text(authctxt->krb5_ctx, problem));
 253         if (ccache)
 254                 krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 255
 256         restore_uid();
 257
 258         return (0);
 259 }
 260
 261 int
 262 auth_krb5_password(Authctxt *authctxt, const char *password)
 263 {
 264 #ifndef HEIMDAL
 265         krb5_creds creds;
 266         krb5_principal server;
 267         char ccname[40];
 268         int tmpfd;
 269 #endif
 270         krb5_error_code problem;
 271
 272         if (authctxt->pw == NULL)
 273                 return (0);
 274
 275         temporarily_use_uid(authctxt->pw);
 276
 277         problem = krb5_init(authctxt);
 278         if (problem)
 279                 goto out;
 280
 281         problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
 282                     &authctxt->krb5_user);
 283         if (problem)
 284                 goto out;
 285
 286 #ifdef HEIMDAL
 287         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops,
 288             &authctxt->krb5_fwd_ccache);
 289         if (problem)
 290                 goto out;
 291
 292         problem = krb5_cc_initialize(authctxt->krb5_ctx,
 293             authctxt->krb5_fwd_ccache, authctxt->krb5_user);
 294         if (problem)
 295                 goto out;
 296
 297         restore_uid();
 298         problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
 299             authctxt->krb5_fwd_ccache, password, 1, NULL);
 300         temporarily_use_uid(authctxt->pw);
 301
 302         if (problem)
 303                 goto out;
 304
 305 #else
 306         problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
 307             authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
 308         if (problem)
 309                 goto out;
 310
 311         problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
 312             KRB5_NT_SRV_HST, &server);
 313         if (problem)
 314                 goto out;
 315
 316         restore_uid();
 317         problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
 318             NULL, NULL, NULL);
 319         krb5_free_principal(authctxt->krb5_ctx, server);
 320         temporarily_use_uid(authctxt->pw);
 321         if (problem)
 322                 goto out;
 323
 324         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 325                           authctxt->pw->pw_name)) {
 326                 problem = -1;
 327                 goto out;
 328         }
 329
 330         snprintf(ccname,sizeof(ccname),"FILE:/tmp/krb5cc_%d_XXXXXX",geteuid());
 331
 332         if ((tmpfd = mkstemp(ccname+strlen("FILE:")))==-1) {
 333                 log("mkstemp(): %.100s", strerror(errno));
 334                 problem = errno;
 335                 goto out;
 336         }
 337
 338         if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
 339                 log("fchmod(): %.100s", strerror(errno));
 340                 close(tmpfd);
 341                 problem = errno;
 342                 goto out;
 343         }
 344         close(tmpfd);
 345
 346         problem = krb5_cc_resolve(authctxt->krb5_ctx, ccname, &authctxt->krb5_fwd_ccache);
 347         if (problem)
 348                 goto out;
 349
 350         problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 351                                      authctxt->krb5_user);
 352         if (problem)
 353                 goto out;
 354
 355         problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 356                                  &creds);
 357         if (problem)
 358                 goto out;
 359 #endif
 360
 361         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 362
 363  out:
 364         restore_uid();
 365
 366         if (problem) {
 367                 if (authctxt->krb5_ctx != NULL && problem!=-1)
 368                         debug("Kerberos password authentication failed: %s",
 369                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 370                 else
 371                         debug("Kerberos password authentication failed: %d",
 372                             problem);
 373
 374                 krb5_cleanup_proc(authctxt);
 375
 376                 if (options.kerberos_or_local_passwd)
 377                         return (-1);
 378                 else
 379                         return (0);
 380         }
 381         return (1);
 382 }
 383
 384 void
 385 krb5_cleanup_proc(void *context)
 386 {
 387         Authctxt *authctxt = (Authctxt *)context;
 388
 389         debug("krb5_cleanup_proc called");
 390         if (authctxt->krb5_fwd_ccache) {
 391                 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 392                 authctxt->krb5_fwd_ccache = NULL;
 393         }
 394         if (authctxt->krb5_user) {
 395                 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
 396                 authctxt->krb5_user = NULL;
 397         }
 398         if (authctxt->krb5_auth_ctx) {
 399                 krb5_auth_con_free(authctxt->krb5_ctx,
 400                     authctxt->krb5_auth_ctx);
 401                 authctxt->krb5_auth_ctx = NULL;
 402         }
 403         if (authctxt->krb5_ctx) {
 404                 krb5_free_context(authctxt->krb5_ctx);
 405                 authctxt->krb5_ctx = NULL;
 406         }
 407 }
 408
 409 #endif /* KRB5 */