openssh/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 1.16 2005/11/21 09:42:10 dtucker 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         }
  58         return (0);
  59 }
  60
  61 int
  62 auth_krb5_password(Authctxt *authctxt, const char *password)
  63 {
  64 #ifndef HEIMDAL
  65         krb5_creds creds;
  66         krb5_principal server;
  67 #endif
  68         krb5_error_code problem;
  69         krb5_ccache ccache = NULL;
  70         int len;
  71
  72         temporarily_use_uid(authctxt->pw);
  73
  74         problem = krb5_init(authctxt);
  75         if (problem)
  76                 goto out;
  77
  78         problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
  79                     &authctxt->krb5_user);
  80         if (problem)
  81                 goto out;
  82
  83 #ifdef HEIMDAL
  84         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops, &ccache);
  85         if (problem)
  86                 goto out;
  87
  88         problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
  89                 authctxt->krb5_user);
  90         if (problem)
  91                 goto out;
  92
  93         restore_uid();
  94
  95         problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
  96             ccache, password, 1, NULL);
  97
  98         temporarily_use_uid(authctxt->pw);
  99
 100         if (problem)
 101                 goto out;
 102
 103         problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops,
 104             &authctxt->krb5_fwd_ccache);
 105         if (problem)
 106                 goto out;
 107
 108         problem = krb5_cc_copy_cache(authctxt->krb5_ctx, ccache,
 109             authctxt->krb5_fwd_ccache);
 110         krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 111         ccache = NULL;
 112         if (problem)
 113                 goto out;
 114
 115 #else
 116         problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
 117             authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
 118         if (problem)
 119                 goto out;
 120
 121         problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
 122             KRB5_NT_SRV_HST, &server);
 123         if (problem)
 124                 goto out;
 125
 126         restore_uid();
 127         problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
 128             NULL, NULL, NULL);
 129         krb5_free_principal(authctxt->krb5_ctx, server);
 130         temporarily_use_uid(authctxt->pw);
 131         if (problem)
 132                 goto out;
 133
 134         if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
 135                           authctxt->pw->pw_name)) {
 136                 problem = -1;
 137                 goto out;
 138         }
 139
 140         problem = ssh_krb5_cc_gen(authctxt->krb5_ctx, &authctxt->krb5_fwd_ccache);
 141         if (problem)
 142                 goto out;
 143
 144         problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 145                                      authctxt->krb5_user);
 146         if (problem)
 147                 goto out;
 148
 149         problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
 150                                  &creds);
 151         if (problem)
 152                 goto out;
 153 #endif
 154
 155         authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 156
 157         len = strlen(authctxt->krb5_ticket_file) + 6;
 158         authctxt->krb5_ccname = xmalloc(len);
 159 #ifdef USE_CCAPI
 160         snprintf(authctxt->krb5_ccname, len, "API:%s",
 161             authctxt->krb5_ticket_file);
 162 #else
 163         snprintf(authctxt->krb5_ccname, len, "FILE:%s",
 164             authctxt->krb5_ticket_file);
 165 #endif
 166
 167 #ifdef USE_PAM
 168         if (options.use_pam)
 169                 do_pam_putenv("KRB5CCNAME", authctxt->krb5_ccname);
 170 #endif
 171
 172  out:
 173         restore_uid();
 174
 175         if (problem) {
 176                 if (ccache)
 177                         krb5_cc_destroy(authctxt->krb5_ctx, ccache);
 178
 179                 if (authctxt->krb5_ctx != NULL && problem!=-1)
 180                         debug("Kerberos password authentication failed: %s",
 181                             krb5_get_err_text(authctxt->krb5_ctx, problem));
 182                 else
 183                         debug("Kerberos password authentication failed: %d",
 184                             problem);
 185
 186                 krb5_cleanup_proc(authctxt);
 187
 188                 if (options.kerberos_or_local_passwd)
 189                         return (-1);
 190                 else
 191                         return (0);
 192         }
 193         return (authctxt->valid ? 1 : 0);
 194 }
 195
 196 void
 197 krb5_cleanup_proc(Authctxt *authctxt)
 198 {
 199         debug("krb5_cleanup_proc called");
 200         if (authctxt->krb5_fwd_ccache) {
 201                 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
 202                 authctxt->krb5_fwd_ccache = NULL;
 203         }
 204         if (authctxt->krb5_user) {
 205                 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
 206                 authctxt->krb5_user = NULL;
 207         }
 208         if (authctxt->krb5_ctx) {
 209                 krb5_free_context(authctxt->krb5_ctx);
 210                 authctxt->krb5_ctx = NULL;
 211         }
 212 }
 213
 214 #ifndef HEIMDAL
 215 krb5_error_code
 216 ssh_krb5_cc_gen(krb5_context ctx, krb5_ccache *ccache) {
 217         int ret;
 218         char ccname[40];
 219         mode_t old_umask;
 220 #ifdef USE_CCAPI
 221         char cctemplate[] = "API:krb5cc_%d";
 222 #else
 223         char cctemplate[] = "FILE:/tmp/krb5cc_%d_XXXXXXXXXX";
 224         int tmpfd;
 225 #endif
 226
 227         ret = snprintf(ccname, sizeof(ccname),
 228             cctemplate, geteuid());
 229         if (ret < 0 || (size_t)ret >= sizeof(ccname))
 230                 return ENOMEM;
 231
 232 #ifndef USE_CCAPI
 233         old_umask = umask(0177);
 234         tmpfd = mkstemp(ccname + strlen("FILE:"));
 235         umask(old_umask);
 236         if (tmpfd == -1) {
 237                 logit("mkstemp(): %.100s", strerror(errno));
 238                 return errno;
 239         }
 240
 241         if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
 242                 logit("fchmod(): %.100s", strerror(errno));
 243                 close(tmpfd);
 244                 return errno;
 245         }
 246         close(tmpfd);
 247 #endif
 248
 249         return (krb5_cc_resolve(ctx, ccname, ccache));
 250 }
 251 #endif /* !HEIMDAL */
 252 #endif /* KRB5 */