gss-serv-krb5.c

   1 /* $OpenBSD: gss-serv-krb5.c,v 1.6 2006/07/02 18:36:47 stevesk 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 <string.h>
  33
  34 #include "auth.h"
  35 #include "xmalloc.h"
  36 #include "log.h"
  37 #include "servconf.h"
  38
  39 #include "ssh-gss.h"
  40
  41 extern ServerOptions options;
  42
  43 #ifdef HEIMDAL
  44 # include <krb5.h>
  45 #else
  46 # ifdef HAVE_GSSAPI_KRB5_H
  47 #  include <gssapi_krb5.h>
  48 # elif HAVE_GSSAPI_GSSAPI_KRB5_H
  49 #  include <gssapi/gssapi_krb5.h>
  50 # endif
  51 #endif
  52
  53 static krb5_context krb_context = NULL;
  54
  55 /* Initialise the krb5 library, for the stuff that GSSAPI won't do */
  56
  57 static int
  58 ssh_gssapi_krb5_init(void)
  59 {
  60         krb5_error_code problem;
  61
  62         if (krb_context != NULL)
  63                 return 1;
  64
  65         problem = krb5_init_context(&krb_context);
  66         if (problem) {
  67                 logit("Cannot initialize krb5 context");
  68                 return 0;
  69         }
  70
  71         return 1;
  72 }
  73
  74 /* Check if this user is OK to login. This only works with krb5 - other
  75  * GSSAPI mechanisms will need their own.
  76  * Returns true if the user is OK to log in, otherwise returns 0
  77  */
  78
  79 static int
  80 ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name)
  81 {
  82         krb5_principal princ;
  83         int retval;
  84
  85         if (ssh_gssapi_krb5_init() == 0)
  86                 return 0;
  87
  88         if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
  89             &princ))) {
  90                 logit("krb5_parse_name(): %.100s",
  91                     krb5_get_err_text(krb_context, retval));
  92                 return 0;
  93         }
  94         if (krb5_kuserok(krb_context, princ, name)) {
  95                 retval = 1;
  96                 logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
  97                     name, (char *)client->displayname.value);
  98         } else
  99                 retval = 0;
 100
 101         krb5_free_principal(krb_context, princ);
 102         return retval;
 103 }
 104
 105
 106 /* This writes out any forwarded credentials from the structure populated
 107  * during userauth. Called after we have setuid to the user */
 108
 109 static void
 110 ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
 111 {
 112         krb5_ccache ccache;
 113         krb5_error_code problem;
 114         krb5_principal princ;
 115         OM_uint32 maj_status, min_status;
 116         int len;
 117
 118         if (client->creds == NULL) {
 119                 debug("No credentials stored");
 120                 return;
 121         }
 122
 123         if (ssh_gssapi_krb5_init() == 0)
 124                 return;
 125
 126 #ifdef HEIMDAL
 127         if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
 128                 logit("krb5_cc_gen_new(): %.100s",
 129                     krb5_get_err_text(krb_context, problem));
 130                 return;
 131         }
 132 #else
 133         if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) {
 134                 logit("ssh_krb5_cc_gen(): %.100s",
 135                     krb5_get_err_text(krb_context, problem));
 136                 return;
 137         }
 138 #endif  /* #ifdef HEIMDAL */
 139
 140         if ((problem = krb5_parse_name(krb_context,
 141             client->exportedname.value, &princ))) {
 142                 logit("krb5_parse_name(): %.100s",
 143                     krb5_get_err_text(krb_context, problem));
 144                 krb5_cc_destroy(krb_context, ccache);
 145                 return;
 146         }
 147
 148         if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
 149                 logit("krb5_cc_initialize(): %.100s",
 150                     krb5_get_err_text(krb_context, problem));
 151                 krb5_free_principal(krb_context, princ);
 152                 krb5_cc_destroy(krb_context, ccache);
 153                 return;
 154         }
 155
 156         krb5_free_principal(krb_context, princ);
 157
 158         if ((maj_status = gss_krb5_copy_ccache(&min_status,
 159             client->creds, ccache))) {
 160                 logit("gss_krb5_copy_ccache() failed");
 161                 krb5_cc_destroy(krb_context, ccache);
 162                 return;
 163         }
 164
 165         client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
 166         client->store.envvar = "KRB5CCNAME";
 167         len = strlen(client->store.filename) + 6;
 168         client->store.envval = xmalloc(len);
 169         snprintf(client->store.envval, len, "FILE:%s", client->store.filename);
 170
 171 #ifdef USE_PAM
 172         if (options.use_pam)
 173                 do_pam_putenv(client->store.envvar, client->store.envval);
 174 #endif
 175
 176         krb5_cc_close(krb_context, ccache);
 177
 178         return;
 179 }
 180
 181 ssh_gssapi_mech gssapi_kerberos_mech = {
 182         "toWM5Slw5Ew8Mqkay+al2g==",
 183         "Kerberos",
 184         {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
 185         NULL,
 186         &ssh_gssapi_krb5_userok,
 187         NULL,
 188         &ssh_gssapi_krb5_storecreds
 189 };
 190
 191 #endif /* KRB5 */
 192
 193 #endif /* GSSAPI */