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