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 1.15 2003/11/21 11:57:02 djm Exp $");
  32 RCSID("$FreeBSD$");
  33
  34 #include "ssh.h"
  35 #include "ssh1.h"
  36 #include "packet.h"
  37 #include "xmalloc.h"
  38 #include "log.h"
  39 #include "servconf.h"
  40 #include "uidswap.h"
  41 #include "auth.h"
  42
  43 #ifdef KRB5
  44 #include <krb5.h>
  45
  46 extern ServerOptions     options;
  47
  48 static int
  49 krb5_init(void *context)
  50 {
  51         Authctxt *authctxt = (Authctxt *)context;
  52         krb5_error_code problem;
  53
  54         if (authctxt->krb5_ctx == NULL) {
  55                 problem = krb5_init_context(&authctxt->krb5_ctx);
  56                 if (problem)
  57                         return (problem);
  58         }
  59         return (0);
  60 }
  61
  62 int
  63 auth_krb5_password(Authctxt *authctxt, const char *password)
  64 {
  65 #ifndef HEIMDAL
  66         krb5_creds creds;
  67         krb5_principal server;
  68 #endif
  69         krb5_error_code problem;
  70         krb5_ccache ccache = NULL;
  71         int len;
  72
  73         if (!authctxt->valid)
  74                 return (0);
  75
  76         temporarily_use_uid(authctxt->pw);
  77
  78         problem = krb5_init(authctxt);
  79         if (problem)
  80                 goto out;
  81
  82         problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
  83                     &authctxt->krb5_user);
  84         if (problem)
  85                 goto out;
  86
  87 #ifdef HEIMDAL
  88         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops, &ccache);
  89         if (problem)
  90                 goto out;
  91
  92         problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
  93                 authctxt->krb5_user);
  94         if (problem)
  95                 goto out;
  96
  97         restore_uid();
  98
  99         problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
 100             ccache, password, 1, NULL);
 101
 102         temporarily_use_uid(authctxt->pw);
 103
 104         if (problem)
 105                 goto out;
 106
 107         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops,
 108             &authctxt->krb5_fwd_ccache);
 109         if (problem)
 110                 goto out;
 111
 112         problem = krb5_cc_copy_cache(authctxt->krb5_ctx, ccache,
 113             authctxt->krb5_fwd_ccache);
 114         krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 115         ccache = NULL;
 116         if (problem)
 117                 goto out;
 118
 119 #else
 120         problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
 121             authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
 122         if (problem)
 123                 goto out;
 124
 125         problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
 126             KRB5_NT_SRV_HST, &server);
 127         if (problem)
 128                 goto out;
 129
 130         restore_uid();
 131         problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
 132             NULL, NULL, NULL);
 133         krb5_free_principal(authctxt->krb5_ctx, server);
 134         temporarily_use_uid(authctxt->pw);
 135         if (problem)
 136                 goto out;
 137
 138         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 139                           authctxt->pw->pw_name)) {
 140                 problem = -1;
 141                 goto out;
 142         }
 143
 144         problem = ssh_krb5_cc_gen(authctxt->krb5_ctx, &authctxt->krb5_fwd_ccache);
 145         if (problem)
 146                 goto out;
 147
 148         problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 149                                      authctxt->krb5_user);
 150         if (problem)
 151                 goto out;
 152
 153         problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 154                                  &creds);
 155         if (problem)
 156                 goto out;
 157 #endif
 158
 159         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 160
 161         len = strlen(authctxt->krb5_ticket_file) + 6;
 162         authctxt->krb5_ccname = xmalloc(len);
 163         snprintf(authctxt->krb5_ccname, len, "FILE:%s",
 164             authctxt->krb5_ticket_file);
 165
 166 #ifdef USE_PAM
 167         if (options.use_pam)
 168                 do_pam_putenv("KRB5CCNAME", authctxt->krb5_ccname);
 169 #endif
 170
 171  out:
 172         restore_uid();
 173
 174         if (problem) {
 175                 if (ccache)
 176                         krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 177
 178                 if (authctxt->krb5_ctx != NULL && problem!=-1)
 179                         debug("Kerberos password authentication failed: %s",
 180                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 181                 else
 182                         debug("Kerberos password authentication failed: %d",
 183                             problem);
 184
 185                 krb5_cleanup_proc(authctxt);
 186
 187                 if (options.kerberos_or_local_passwd)
 188                         return (-1);
 189                 else
 190                         return (0);
 191         }
 192         return (1);
 193 }
 194
 195 void
 196 krb5_cleanup_proc(Authctxt *authctxt)
 197 {
 198         debug("krb5_cleanup_proc called");
 199         if (authctxt->krb5_fwd_ccache) {
 200                 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 201                 authctxt->krb5_fwd_ccache = NULL;
 202         }
 203         if (authctxt->krb5_user) {
 204                 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
 205                 authctxt->krb5_user = NULL;
 206         }
 207         if (authctxt->krb5_ctx) {
 208                 krb5_free_context(authctxt->krb5_ctx);
 209                 authctxt->krb5_ctx = NULL;
 210         }
 211 }
 212
 213 #ifndef HEIMDAL
 214 krb5_error_code
 215 ssh_krb5_cc_gen(krb5_context ctx, krb5_ccache *ccache) {
 216         int tmpfd, ret;
 217         char ccname[40];
 218         mode_t old_umask;
 219
 220         ret = snprintf(ccname, sizeof(ccname),
 221             "FILE:/tmp/krb5cc_%d_XXXXXXXXXX", geteuid());
 222         if (ret == -1 || ret >= sizeof(ccname))
 223                 return ENOMEM;
 224
 225         old_umask = umask(0177);
 226         tmpfd = mkstemp(ccname + strlen("FILE:"));
 227         umask(old_umask);
 228         if (tmpfd == -1) {
 229                 logit("mkstemp(): %.100s", strerror(errno));
 230                 return errno;
 231         }
 232
 233         if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
 234                 logit("fchmod(): %.100s", strerror(errno));
 235                 close(tmpfd);
 236                 return errno;
 237         }
 238         close(tmpfd);
 239
 240         return (krb5_cc_resolve(ctx, ccname, ccache));
 241 }
 242 #endif /* !HEIMDAL */
 243 #endif /* KRB5 */