auth-krb5.c

   1 /* $OpenBSD: auth-krb5.c,v 1.18 2006/05/06 08:35:40 dtucker Exp $ */
   2 /*
   3  *    Kerberos v5 authentication and ticket-passing routines.
   4  *
   5  * $FreeBSD: 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
  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 <errno.h>
  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         temporarily_use_uid(authctxt->pw);
  74
  75         problem = krb5_init(authctxt);
  76         if (problem)
  77                 goto out;
  78
  79         problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
  80                     &authctxt->krb5_user);
  81         if (problem)
  82                 goto out;
  83
  84 #ifdef HEIMDAL
  85         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops, &ccache);
  86         if (problem)
  87                 goto out;
  88
  89         problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
  90                 authctxt->krb5_user);
  91         if (problem)
  92                 goto out;
  93
  94         restore_uid();
  95
  96         problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
  97             ccache, password, 1, NULL);
  98
  99         temporarily_use_uid(authctxt->pw);
 100
 101         if (problem)
 102                 goto out;
 103
 104         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops,
 105             &authctxt->krb5_fwd_ccache);
 106         if (problem)
 107                 goto out;
 108
 109         problem = krb5_cc_copy_cache(authctxt->krb5_ctx, ccache,
 110             authctxt->krb5_fwd_ccache);
 111         krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 112         ccache = NULL;
 113         if (problem)
 114                 goto out;
 115
 116 #else
 117         problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
 118             authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
 119         if (problem)
 120                 goto out;
 121
 122         problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
 123             KRB5_NT_SRV_HST, &server);
 124         if (problem)
 125                 goto out;
 126
 127         restore_uid();
 128         problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
 129             NULL, NULL, NULL);
 130         krb5_free_principal(authctxt->krb5_ctx, server);
 131         temporarily_use_uid(authctxt->pw);
 132         if (problem)
 133                 goto out;
 134
 135         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 136                           authctxt->pw->pw_name)) {
 137                 problem = -1;
 138                 goto out;
 139         }
 140
 141         problem = ssh_krb5_cc_gen(authctxt->krb5_ctx, &authctxt->krb5_fwd_ccache);
 142         if (problem)
 143                 goto out;
 144
 145         problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 146                                      authctxt->krb5_user);
 147         if (problem)
 148                 goto out;
 149
 150         problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 151                                  &creds);
 152         if (problem)
 153                 goto out;
 154 #endif
 155
 156         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 157
 158         len = strlen(authctxt->krb5_ticket_file) + 6;
 159         authctxt->krb5_ccname = xmalloc(len);
 160         snprintf(authctxt->krb5_ccname, len, "FILE:%s",
 161             authctxt->krb5_ticket_file);
 162
 163 #ifdef USE_PAM
 164         if (options.use_pam)
 165                 do_pam_putenv("KRB5CCNAME", authctxt->krb5_ccname);
 166 #endif
 167
 168  out:
 169         restore_uid();
 170
 171         if (problem) {
 172                 if (ccache)
 173                         krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 174
 175                 if (authctxt->krb5_ctx != NULL && problem!=-1)
 176                         debug("Kerberos password authentication failed: %s",
 177                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 178                 else
 179                         debug("Kerberos password authentication failed: %d",
 180                             problem);
 181
 182                 krb5_cleanup_proc(authctxt);
 183
 184                 if (options.kerberos_or_local_passwd)
 185                         return (-1);
 186                 else
 187                         return (0);
 188         }
 189         return (authctxt->valid ? 1 : 0);
 190 }
 191
 192 void
 193 krb5_cleanup_proc(Authctxt *authctxt)
 194 {
 195         debug("krb5_cleanup_proc called");
 196         if (authctxt->krb5_fwd_ccache) {
 197                 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 198                 authctxt->krb5_fwd_ccache = NULL;
 199         }
 200         if (authctxt->krb5_user) {
 201                 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
 202                 authctxt->krb5_user = NULL;
 203         }
 204         if (authctxt->krb5_ctx) {
 205                 krb5_free_context(authctxt->krb5_ctx);
 206                 authctxt->krb5_ctx = NULL;
 207         }
 208 }
 209
 210 #ifndef HEIMDAL
 211 krb5_error_code
 212 ssh_krb5_cc_gen(krb5_context ctx, krb5_ccache *ccache) {
 213         int tmpfd, ret;
 214         char ccname[40];
 215         mode_t old_umask;
 216
 217         ret = snprintf(ccname, sizeof(ccname),
 218             "FILE:/tmp/krb5cc_%d_XXXXXXXXXX", geteuid());
 219         if (ret < 0 || (size_t)ret >= sizeof(ccname))
 220                 return ENOMEM;
 221
 222         old_umask = umask(0177);
 223         tmpfd = mkstemp(ccname + strlen("FILE:"));
 224         umask(old_umask);
 225         if (tmpfd == -1) {
 226                 logit("mkstemp(): %.100s", strerror(errno));
 227                 return errno;
 228         }
 229
 230         if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
 231                 logit("fchmod(): %.100s", strerror(errno));
 232                 close(tmpfd);
 233                 return errno;
 234         }
 235         close(tmpfd);
 236
 237         return (krb5_cc_resolve(ctx, ccname, ccache));
 238 }
 239 #endif /* !HEIMDAL */
 240 #endif /* KRB5 */