crypto/openssh/auth-krb5.c

   1 /* $OpenBSD: auth-krb5.c,v 1.19 2006/08/03 03:34:41 deraadt Exp $ */
   2 /*
   3  *    Kerberos v5 authentication and ticket-passing routines.
   4  *
   5  * $xFreeBSD: src/crypto/openssh/auth-krb5.c,v 1.6 2001/02/13 16:58:04 assar Exp$
   6  */
   7 /*
   8  * Copyright (c) 2002 Daniel Kouril.  All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30
  31 #include "includes.h"
  32 __RCSID("$FreeBSD$");
  33
  34 #include <sys/types.h>
  35 #include <pwd.h>
  36 #include <stdarg.h>
  37
  38 #include "xmalloc.h"
  39 #include "ssh.h"
  40 #include "ssh1.h"
  41 #include "packet.h"
  42 #include "log.h"
  43 #include "buffer.h"
  44 #include "servconf.h"
  45 #include "uidswap.h"
  46 #include "key.h"
  47 #include "hostfile.h"
  48 #include "auth.h"
  49
  50 #ifdef KRB5
  51 #include <errno.h>
  52 #include <unistd.h>
  53 #include <string.h>
  54 #include <krb5.h>
  55
  56 extern ServerOptions     options;
  57
  58 static int
  59 krb5_init(void *context)
  60 {
  61         Authctxt *authctxt = (Authctxt *)context;
  62         krb5_error_code problem;
  63
  64         if (authctxt->krb5_ctx == NULL) {
  65                 problem = krb5_init_context(&authctxt->krb5_ctx);
  66                 if (problem)
  67                         return (problem);
  68         }
  69         return (0);
  70 }
  71
  72 int
  73 auth_krb5_password(Authctxt *authctxt, const char *password)
  74 {
  75 #ifndef HEIMDAL
  76         krb5_creds creds;
  77         krb5_principal server;
  78 #endif
  79         krb5_error_code problem;
  80         krb5_ccache ccache = NULL;
  81         int len;
  82
  83         temporarily_use_uid(authctxt->pw);
  84
  85         problem = krb5_init(authctxt);
  86         if (problem)
  87                 goto out;
  88
  89         problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
  90                     &authctxt->krb5_user);
  91         if (problem)
  92                 goto out;
  93
  94 #ifdef HEIMDAL
  95         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops, &ccache);
  96         if (problem)
  97                 goto out;
  98
  99         problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
 100                 authctxt->krb5_user);
 101         if (problem)
 102                 goto out;
 103
 104         restore_uid();
 105
 106         problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
 107             ccache, password, 1, NULL);
 108
 109         temporarily_use_uid(authctxt->pw);
 110
 111         if (problem)
 112                 goto out;
 113
 114         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops,
 115             &authctxt->krb5_fwd_ccache);
 116         if (problem)
 117                 goto out;
 118
 119         problem = krb5_cc_copy_cache(authctxt->krb5_ctx, ccache,
 120             authctxt->krb5_fwd_ccache);
 121         krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 122         ccache = NULL;
 123         if (problem)
 124                 goto out;
 125
 126 #else
 127         problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
 128             authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
 129         if (problem)
 130                 goto out;
 131
 132         problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
 133             KRB5_NT_SRV_HST, &server);
 134         if (problem)
 135                 goto out;
 136
 137         restore_uid();
 138         problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
 139             NULL, NULL, NULL);
 140         krb5_free_principal(authctxt->krb5_ctx, server);
 141         temporarily_use_uid(authctxt->pw);
 142         if (problem)
 143                 goto out;
 144
 145         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 146                           authctxt->pw->pw_name)) {
 147                 problem = -1;
 148                 goto out;
 149         }
 150
 151         problem = ssh_krb5_cc_gen(authctxt->krb5_ctx, &authctxt->krb5_fwd_ccache);
 152         if (problem)
 153                 goto out;
 154
 155         problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 156                                      authctxt->krb5_user);
 157         if (problem)
 158                 goto out;
 159
 160         problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 161                                  &creds);
 162         if (problem)
 163                 goto out;
 164 #endif
 165
 166         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 167
 168         len = strlen(authctxt->krb5_ticket_file) + 6;
 169         authctxt->krb5_ccname = xmalloc(len);
 170         snprintf(authctxt->krb5_ccname, len, "FILE:%s",
 171             authctxt->krb5_ticket_file);
 172
 173 #ifdef USE_PAM
 174         if (options.use_pam)
 175                 do_pam_putenv("KRB5CCNAME", authctxt->krb5_ccname);
 176 #endif
 177
 178  out:
 179         restore_uid();
 180
 181         if (problem) {
 182                 if (ccache)
 183                         krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 184
 185                 if (authctxt->krb5_ctx != NULL && problem!=-1)
 186                         debug("Kerberos password authentication failed: %s",
 187                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 188                 else
 189                         debug("Kerberos password authentication failed: %d",
 190                             problem);
 191
 192                 krb5_cleanup_proc(authctxt);
 193
 194                 if (options.kerberos_or_local_passwd)
 195                         return (-1);
 196                 else
 197                         return (0);
 198         }
 199         return (authctxt->valid ? 1 : 0);
 200 }
 201
 202 void
 203 krb5_cleanup_proc(Authctxt *authctxt)
 204 {
 205         debug("krb5_cleanup_proc called");
 206         if (authctxt->krb5_fwd_ccache) {
 207                 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 208                 authctxt->krb5_fwd_ccache = NULL;
 209         }
 210         if (authctxt->krb5_user) {
 211                 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
 212                 authctxt->krb5_user = NULL;
 213         }
 214         if (authctxt->krb5_ctx) {
 215                 krb5_free_context(authctxt->krb5_ctx);
 216                 authctxt->krb5_ctx = NULL;
 217         }
 218 }
 219
 220 #ifndef HEIMDAL
 221 krb5_error_code
 222 ssh_krb5_cc_gen(krb5_context ctx, krb5_ccache *ccache) {
 223         int tmpfd, ret;
 224         char ccname[40];
 225         mode_t old_umask;
 226
 227         ret = snprintf(ccname, sizeof(ccname),
 228             "FILE:/tmp/krb5cc_%d_XXXXXXXXXX", geteuid());
 229         if (ret < 0 || (size_t)ret >= sizeof(ccname))
 230                 return ENOMEM;
 231
 232         old_umask = umask(0177);
 233         tmpfd = mkstemp(ccname + strlen("FILE:"));
 234         umask(old_umask);
 235         if (tmpfd == -1) {
 236                 logit("mkstemp(): %.100s", strerror(errno));
 237                 return errno;
 238         }
 239
 240         if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
 241                 logit("fchmod(): %.100s", strerror(errno));
 242                 close(tmpfd);
 243                 return errno;
 244         }
 245         close(tmpfd);
 246
 247         return (krb5_cc_resolve(ctx, ccname, ccache));
 248 }
 249 #endif /* !HEIMDAL */
 250 #endif /* KRB5 */