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 1.15 2003/11/21 11:57:02 djm 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 #ifdef KRB5_INIT_ETS
  58                 krb5_init_ets(authctxt->krb5_ctx);
  59 #endif
  60         }
  61         return (0);
  62 }
  63
  64 int
  65 auth_krb5_password(Authctxt *authctxt, const char *password)
  66 {
  67 #ifndef HEIMDAL
  68         krb5_creds creds;
  69         krb5_principal server;
  70         char ccname[40];
  71         int tmpfd;
  72         mode_t old_umask;
  73 #endif
  74         krb5_error_code problem;
  75         krb5_ccache ccache = NULL;
  76         int len;
  77
  78         if (!authctxt->valid)
  79                 return (0);
  80
  81         temporarily_use_uid(authctxt->pw);
  82
  83         problem = krb5_init(authctxt);
  84         if (problem)
  85                 goto out;
  86
  87         problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
  88                     &authctxt->krb5_user);
  89         if (problem)
  90                 goto out;
  91
  92 #ifdef HEIMDAL
  93         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops, &ccache);
  94         if (problem)
  95                 goto out;
  96
  97         problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
  98                 authctxt->krb5_user);
  99         if (problem)
 100                 goto out;
 101
 102         restore_uid();
 103
 104         problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
 105             ccache, password, 1, NULL);
 106
 107         temporarily_use_uid(authctxt->pw);
 108
 109         if (problem)
 110                 goto out;
 111
 112         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops,
 113             &authctxt->krb5_fwd_ccache);
 114         if (problem)
 115                 goto out;
 116
 117         problem = krb5_cc_copy_cache(authctxt->krb5_ctx, ccache,
 118             authctxt->krb5_fwd_ccache);
 119         krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 120         ccache = NULL;
 121         if (problem)
 122                 goto out;
 123
 124 #else
 125         problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
 126             authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
 127         if (problem)
 128                 goto out;
 129
 130         problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
 131             KRB5_NT_SRV_HST, &server);
 132         if (problem)
 133                 goto out;
 134
 135         restore_uid();
 136         problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
 137             NULL, NULL, NULL);
 138         krb5_free_principal(authctxt->krb5_ctx, server);
 139         temporarily_use_uid(authctxt->pw);
 140         if (problem)
 141                 goto out;
 142
 143         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 144                           authctxt->pw->pw_name)) {
 145                 problem = -1;
 146                 goto out;
 147         }
 148
 149         snprintf(ccname,sizeof(ccname),"FILE:/tmp/krb5cc_%d_XXXXXX",geteuid());
 150
 151         old_umask = umask(0177);
 152         tmpfd = mkstemp(ccname + strlen("FILE:"));
 153         umask(old_umask);
 154         if (tmpfd == -1) {
 155                 logit("mkstemp(): %.100s", strerror(errno));
 156                 problem = errno;
 157                 goto out;
 158         }
 159
 160         if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
 161                 logit("fchmod(): %.100s", strerror(errno));
 162                 close(tmpfd);
 163                 problem = errno;
 164                 goto out;
 165         }
 166         close(tmpfd);
 167
 168         problem = krb5_cc_resolve(authctxt->krb5_ctx, ccname, &authctxt->krb5_fwd_ccache);
 169         if (problem)
 170                 goto out;
 171
 172         problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 173                                      authctxt->krb5_user);
 174         if (problem)
 175                 goto out;
 176
 177         problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 178                                  &creds);
 179         if (problem)
 180                 goto out;
 181 #endif
 182
 183         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 184
 185         len = strlen(authctxt->krb5_ticket_file) + 6;
 186         authctxt->krb5_ccname = xmalloc(len);
 187         snprintf(authctxt->krb5_ccname, len, "FILE:%s",
 188             authctxt->krb5_ticket_file);
 189
 190 #ifdef USE_PAM
 191         if (options.use_pam)
 192                 do_pam_putenv("KRB5CCNAME", authctxt->krb5_ccname);
 193 #endif
 194
 195  out:
 196         restore_uid();
 197
 198         if (problem) {
 199                 if (ccache)
 200                         krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 201
 202                 if (authctxt->krb5_ctx != NULL && problem!=-1)
 203                         debug("Kerberos password authentication failed: %s",
 204                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 205                 else
 206                         debug("Kerberos password authentication failed: %d",
 207                             problem);
 208
 209                 krb5_cleanup_proc(authctxt);
 210
 211                 if (options.kerberos_or_local_passwd)
 212                         return (-1);
 213                 else
 214                         return (0);
 215         }
 216         return (1);
 217 }
 218
 219 void
 220 krb5_cleanup_proc(Authctxt *authctxt)
 221 {
 222         debug("krb5_cleanup_proc called");
 223         if (authctxt->krb5_fwd_ccache) {
 224                 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 225                 authctxt->krb5_fwd_ccache = NULL;
 226         }
 227         if (authctxt->krb5_user) {
 228                 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
 229                 authctxt->krb5_user = NULL;
 230         }
 231         if (authctxt->krb5_ctx) {
 232                 krb5_free_context(authctxt->krb5_ctx);
 233                 authctxt->krb5_ctx = NULL;
 234         }
 235 }
 236
 237 #endif /* KRB5 */