crypto/openssh/gss-serv-krb5.c

   1 /* $OpenBSD: gss-serv-krb5.c,v 1.8 2013/07/20 01:55:13 djm Exp $ */
   2
   3 /*
   4  * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include "includes.h"
  28
  29 #ifdef GSSAPI
  30 #ifdef KRB5
  31
  32 #include <sys/types.h>
  33
  34 #include <stdarg.h>
  35 #include <string.h>
  36
  37 #include "xmalloc.h"
  38 #include "key.h"
  39 #include "hostfile.h"
  40 #include "auth.h"
  41 #include "log.h"
  42 #include "misc.h"
  43 #include "servconf.h"
  44
  45 #include "buffer.h"
  46 #include "ssh-gss.h"
  47
  48 extern ServerOptions options;
  49
  50 #ifdef HEIMDAL
  51 # include <krb5.h>
  52 #endif
  53 #ifdef HAVE_GSSAPI_KRB5_H
  54 # include <gssapi_krb5.h>
  55 #elif HAVE_GSSAPI_GSSAPI_KRB5_H
  56 # include <gssapi/gssapi_krb5.h>
  57 #endif
  58
  59 static krb5_context krb_context = NULL;
  60
  61 /* Initialise the krb5 library, for the stuff that GSSAPI won't do */
  62
  63 static int
  64 ssh_gssapi_krb5_init(void)
  65 {
  66         krb5_error_code problem;
  67
  68         if (krb_context != NULL)
  69                 return 1;
  70
  71         problem = krb5_init_context(&krb_context);
  72         if (problem) {
  73                 logit("Cannot initialize krb5 context");
  74                 return 0;
  75         }
  76
  77         return 1;
  78 }
  79
  80 /* Check if this user is OK to login. This only works with krb5 - other
  81  * GSSAPI mechanisms will need their own.
  82  * Returns true if the user is OK to log in, otherwise returns 0
  83  */
  84
  85 static int
  86 ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name)
  87 {
  88         krb5_principal princ;
  89         int retval;
  90         const char *errmsg;
  91
  92         if (ssh_gssapi_krb5_init() == 0)
  93                 return 0;
  94
  95         if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
  96             &princ))) {
  97                 errmsg = krb5_get_error_message(krb_context, retval);
  98                 logit("krb5_parse_name(): %.100s", errmsg);
  99                 krb5_free_error_message(krb_context, errmsg);
 100                 return 0;
 101         }
 102         if (krb5_kuserok(krb_context, princ, name)) {
 103                 retval = 1;
 104                 logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
 105                     name, (char *)client->displayname.value);
 106         } else
 107                 retval = 0;
 108
 109         krb5_free_principal(krb_context, princ);
 110         return retval;
 111 }
 112
 113
 114 /* This writes out any forwarded credentials from the structure populated
 115  * during userauth. Called after we have setuid to the user */
 116
 117 static void
 118 ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
 119 {
 120         krb5_ccache ccache;
 121         krb5_error_code problem;
 122         krb5_principal princ;
 123         OM_uint32 maj_status, min_status;
 124         int len;
 125         const char *errmsg;
 126
 127         if (client->creds == NULL) {
 128                 debug("No credentials stored");
 129                 return;
 130         }
 131
 132         if (ssh_gssapi_krb5_init() == 0)
 133                 return;
 134
 135 #ifdef HEIMDAL
 136 # ifdef HAVE_KRB5_CC_NEW_UNIQUE
 137         if ((problem = krb5_cc_new_unique(krb_context, krb5_fcc_ops.prefix,
 138             NULL, &ccache)) != 0) {
 139                 errmsg = krb5_get_error_message(krb_context, problem);
 140                 logit("krb5_cc_new_unique(): %.100s", errmsg);
 141 # else
 142         if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
 143             logit("krb5_cc_gen_new(): %.100s",
 144                 krb5_get_err_text(krb_context, problem));
 145 # endif
 146                 krb5_free_error_message(krb_context, errmsg);
 147                 return;
 148         }
 149 #else
 150         if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) {
 151                 errmsg = krb5_get_error_message(krb_context, problem);
 152                 logit("ssh_krb5_cc_gen(): %.100s", errmsg);
 153                 krb5_free_error_message(krb_context, errmsg);
 154                 return;
 155         }
 156 #endif  /* #ifdef HEIMDAL */
 157
 158         if ((problem = krb5_parse_name(krb_context,
 159             client->exportedname.value, &princ))) {
 160                 errmsg = krb5_get_error_message(krb_context, problem);
 161                 logit("krb5_parse_name(): %.100s", errmsg);
 162                 krb5_free_error_message(krb_context, errmsg);
 163                 return;
 164         }
 165
 166         if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
 167                 errmsg = krb5_get_error_message(krb_context, problem);
 168                 logit("krb5_cc_initialize(): %.100s", errmsg);
 169                 krb5_free_error_message(krb_context, errmsg);
 170                 krb5_free_principal(krb_context, princ);
 171                 krb5_cc_destroy(krb_context, ccache);
 172                 return;
 173         }
 174
 175         krb5_free_principal(krb_context, princ);
 176
 177         if ((maj_status = gss_krb5_copy_ccache(&min_status,
 178             client->creds, ccache))) {
 179                 logit("gss_krb5_copy_ccache() failed");
 180                 krb5_cc_destroy(krb_context, ccache);
 181                 return;
 182         }
 183
 184         client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
 185         client->store.envvar = "KRB5CCNAME";
 186         len = strlen(client->store.filename) + 6;
 187         client->store.envval = xmalloc(len);
 188         snprintf(client->store.envval, len, "FILE:%s", client->store.filename);
 189
 190 #ifdef USE_PAM
 191         if (options.use_pam)
 192                 do_pam_putenv(client->store.envvar, client->store.envval);
 193 #endif
 194
 195         krb5_cc_close(krb_context, ccache);
 196
 197         return;
 198 }
 199
 200 ssh_gssapi_mech gssapi_kerberos_mech = {
 201         "toWM5Slw5Ew8Mqkay+al2g==",
 202         "Kerberos",
 203         {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
 204         NULL,
 205         &ssh_gssapi_krb5_userok,
 206         NULL,
 207         &ssh_gssapi_krb5_storecreds
 208 };
 209
 210 #endif /* KRB5 */
 211
 212 #endif /* GSSAPI */