crypto/openssh-4/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 1.16 2005/11/21 09:42:10 dtucker 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
  45 extern ServerOptions     options;
  46
  47 static int
  48 krb5_init(void *context)
  49 {
  50         Authctxt *authctxt = (Authctxt *)context;
  51         krb5_error_code problem;
  52
  53         if (authctxt->krb5_ctx == NULL) {
  54                 problem = krb5_init_context(&authctxt->krb5_ctx);
  55                 if (problem)
  56                         return (problem);
  57         }
  58         return (0);
  59 }
  60
  61 int
  62 auth_krb5_password(Authctxt *authctxt, const char *password)
  63 {
  64 #ifndef HEIMDAL
  65         krb5_creds creds;
  66         krb5_principal server;
  67 #endif
  68         krb5_error_code problem;
  69         krb5_ccache ccache = NULL;
  70         int len;
  71
  72         temporarily_use_uid(authctxt->pw);
  73
  74         problem = krb5_init(authctxt);
  75         if (problem)
  76                 goto out;
  77
  78         problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
  79                     &authctxt->krb5_user);
  80         if (problem)
  81                 goto out;
  82
  83 #ifdef HEIMDAL
  84         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops, &ccache);
  85         if (problem)
  86                 goto out;
  87
  88         problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
  89                 authctxt->krb5_user);
  90         if (problem)
  91                 goto out;
  92
  93         restore_uid();
  94
  95         problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
  96             ccache, password, 1, NULL);
  97
  98         temporarily_use_uid(authctxt->pw);
  99
 100         if (problem)
 101                 goto out;
 102
 103         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops,
 104             &authctxt->krb5_fwd_ccache);
 105         if (problem)
 106                 goto out;
 107
 108         problem = krb5_cc_copy_cache(authctxt->krb5_ctx, ccache,
 109             authctxt->krb5_fwd_ccache);
 110         krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 111         ccache = NULL;
 112         if (problem)
 113                 goto out;
 114
 115 #else
 116         problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
 117             authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
 118         if (problem)
 119                 goto out;
 120
 121         problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
 122             KRB5_NT_SRV_HST, &server);
 123         if (problem)
 124                 goto out;
 125
 126         restore_uid();
 127         problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
 128             NULL, NULL, NULL);
 129         krb5_free_principal(authctxt->krb5_ctx, server);
 130         temporarily_use_uid(authctxt->pw);
 131         if (problem)
 132                 goto out;
 133
 134         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 135                           authctxt->pw->pw_name)) {
 136                 problem = -1;
 137                 goto out;
 138         }
 139
 140         problem = ssh_krb5_cc_gen(authctxt->krb5_ctx, &authctxt->krb5_fwd_ccache);
 141         if (problem)
 142                 goto out;
 143
 144         problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 145                                      authctxt->krb5_user);
 146         if (problem)
 147                 goto out;
 148
 149         problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 150                                  &creds);
 151         if (problem)
 152                 goto out;
 153 #endif
 154
 155         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 156
 157         len = strlen(authctxt->krb5_ticket_file) + 6;
 158         authctxt->krb5_ccname = xmalloc(len);
 159         snprintf(authctxt->krb5_ccname, len, "FILE:%s",
 160             authctxt->krb5_ticket_file);
 161
 162 #ifdef USE_PAM
 163         if (options.use_pam)
 164                 do_pam_putenv("KRB5CCNAME", authctxt->krb5_ccname);
 165 #endif
 166
 167  out:
 168         restore_uid();
 169
 170         if (problem) {
 171                 if (ccache)
 172                         krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 173
 174                 if (authctxt->krb5_ctx != NULL && problem!=-1)
 175                         debug("Kerberos password authentication failed: %s",
 176                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 177                 else
 178                         debug("Kerberos password authentication failed: %d",
 179                             problem);
 180
 181                 krb5_cleanup_proc(authctxt);
 182
 183                 if (options.kerberos_or_local_passwd)
 184                         return (-1);
 185                 else
 186                         return (0);
 187         }
 188         return (authctxt->valid ? 1 : 0);
 189 }
 190
 191 void
 192 krb5_cleanup_proc(Authctxt *authctxt)
 193 {
 194         debug("krb5_cleanup_proc called");
 195         if (authctxt->krb5_fwd_ccache) {
 196                 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 197                 authctxt->krb5_fwd_ccache = NULL;
 198         }
 199         if (authctxt->krb5_user) {
 200                 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
 201                 authctxt->krb5_user = NULL;
 202         }
 203         if (authctxt->krb5_ctx) {
 204                 krb5_free_context(authctxt->krb5_ctx);
 205                 authctxt->krb5_ctx = NULL;
 206         }
 207 }
 208
 209 #ifndef HEIMDAL
 210 krb5_error_code
 211 ssh_krb5_cc_gen(krb5_context ctx, krb5_ccache *ccache) {
 212         int tmpfd, ret;
 213         char ccname[40];
 214         mode_t old_umask;
 215
 216         ret = snprintf(ccname, sizeof(ccname),
 217             "FILE:/tmp/krb5cc_%d_XXXXXXXXXX", geteuid());
 218         if (ret < 0 || (size_t)ret >= sizeof(ccname))
 219                 return ENOMEM;
 220
 221         old_umask = umask(0177);
 222         tmpfd = mkstemp(ccname + strlen("FILE:"));
 223         umask(old_umask);
 224         if (tmpfd == -1) {
 225                 logit("mkstemp(): %.100s", strerror(errno));
 226                 return errno;
 227         }
 228
 229         if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
 230                 logit("fchmod(): %.100s", strerror(errno));
 231                 close(tmpfd);
 232                 return errno;
 233         }
 234         close(tmpfd);
 235
 236         return (krb5_cc_resolve(ctx, ccname, ccache));
 237 }
 238 #endif /* !HEIMDAL */
 239 #endif /* KRB5 */