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