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