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