gss-serv-krb5.c

   1 /* $OpenBSD: gss-serv-krb5.c,v 1.7 2006/08/03 03:34:42 deraadt 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 <string.h>
  35
  36 #include "xmalloc.h"
  37 #include "key.h"
  38 #include "hostfile.h"
  39 #include "auth.h"
  40 #include "log.h"
  41 #include "servconf.h"
  42
  43 #include "buffer.h"
  44 #include "ssh-gss.h"
  45
  46 extern ServerOptions options;
  47
  48 #ifdef HEIMDAL
  49 # include <krb5.h>
  50 #else
  51 # ifdef HAVE_GSSAPI_KRB5_H
  52 #  include <gssapi_krb5.h>
  53 # elif HAVE_GSSAPI_GSSAPI_KRB5_H
  54 #  include <gssapi/gssapi_krb5.h>
  55 # endif
  56 #endif
  57
  58 static krb5_context krb_context = NULL;
  59
  60 /* Initialise the krb5 library, for the stuff that GSSAPI won't do */
  61
  62 static int
  63 ssh_gssapi_krb5_init(void)
  64 {
  65         krb5_error_code problem;
  66
  67         if (krb_context != NULL)
  68                 return 1;
  69
  70         problem = krb5_init_context(&krb_context);
  71         if (problem) {
  72                 logit("Cannot initialize krb5 context");
  73                 return 0;
  74         }
  75
  76         return 1;
  77 }
  78
  79 /* Check if this user is OK to login. This only works with krb5 - other
  80  * GSSAPI mechanisms will need their own.
  81  * Returns true if the user is OK to log in, otherwise returns 0
  82  */
  83
  84 static int
  85 ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name)
  86 {
  87         krb5_principal princ;
  88         int retval;
  89
  90         if (ssh_gssapi_krb5_init() == 0)
  91                 return 0;
  92
  93         if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
  94             &princ))) {
  95                 logit("krb5_parse_name(): %.100s",
  96                     krb5_get_err_text(krb_context, retval));
  97                 return 0;
  98         }
  99         if (krb5_kuserok(krb_context, princ, name)) {
 100                 retval = 1;
 101                 logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
 102                     name, (char *)client->displayname.value);
 103         } else
 104                 retval = 0;
 105
 106         krb5_free_principal(krb_context, princ);
 107         return retval;
 108 }
 109
 110
 111 /* This writes out any forwarded credentials from the structure populated
 112  * during userauth. Called after we have setuid to the user */
 113
 114 static void
 115 ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
 116 {
 117         krb5_ccache ccache;
 118         krb5_error_code problem;
 119         krb5_principal princ;
 120         OM_uint32 maj_status, min_status;
 121         int len;
 122
 123         if (client->creds == NULL) {
 124                 debug("No credentials stored");
 125                 return;
 126         }
 127
 128         if (ssh_gssapi_krb5_init() == 0)
 129                 return;
 130
 131 #ifdef HEIMDAL
 132         if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
 133                 logit("krb5_cc_gen_new(): %.100s",
 134                     krb5_get_err_text(krb_context, problem));
 135                 return;
 136         }
 137 #else
 138         if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) {
 139                 logit("ssh_krb5_cc_gen(): %.100s",
 140                     krb5_get_err_text(krb_context, problem));
 141                 return;
 142         }
 143 #endif  /* #ifdef HEIMDAL */
 144
 145         if ((problem = krb5_parse_name(krb_context,
 146             client->exportedname.value, &princ))) {
 147                 logit("krb5_parse_name(): %.100s",
 148                     krb5_get_err_text(krb_context, problem));
 149                 krb5_cc_destroy(krb_context, ccache);
 150                 return;
 151         }
 152
 153         if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
 154                 logit("krb5_cc_initialize(): %.100s",
 155                     krb5_get_err_text(krb_context, problem));
 156                 krb5_free_principal(krb_context, princ);
 157                 krb5_cc_destroy(krb_context, ccache);
 158                 return;
 159         }
 160
 161         krb5_free_principal(krb_context, princ);
 162
 163         if ((maj_status = gss_krb5_copy_ccache(&min_status,
 164             client->creds, ccache))) {
 165                 logit("gss_krb5_copy_ccache() failed");
 166                 krb5_cc_destroy(krb_context, ccache);
 167                 return;
 168         }
 169
 170         client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
 171         client->store.envvar = "KRB5CCNAME";
 172         len = strlen(client->store.filename) + 6;
 173         client->store.envval = xmalloc(len);
 174         snprintf(client->store.envval, len, "FILE:%s", client->store.filename);
 175
 176 #ifdef USE_PAM
 177         if (options.use_pam)
 178                 do_pam_putenv(client->store.envvar, client->store.envval);
 179 #endif
 180
 181         krb5_cc_close(krb_context, ccache);
 182
 183         return;
 184 }
 185
 186 ssh_gssapi_mech gssapi_kerberos_mech = {
 187         "toWM5Slw5Ew8Mqkay+al2g==",
 188         "Kerberos",
 189         {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
 190         NULL,
 191         &ssh_gssapi_krb5_userok,
 192         NULL,
 193         &ssh_gssapi_krb5_storecreds
 194 };
 195
 196 #endif /* KRB5 */
 197
 198 #endif /* GSSAPI */