gss-serv-krb5.c

   1 /*      $OpenBSD: gss-serv-krb5.c,v 1.1 2003/08/22 10:56:09 markus 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 #include <krb5.h>
  42
  43 static krb5_context krb_context = NULL;
  44
  45 /* Initialise the krb5 library, for the stuff that GSSAPI won't do */
  46
  47 static int
  48 ssh_gssapi_krb5_init()
  49 {
  50         krb5_error_code problem;
  51
  52         if (krb_context != NULL)
  53                 return 1;
  54
  55         problem = krb5_init_context(&krb_context);
  56         if (problem) {
  57                 logit("Cannot initialize krb5 context");
  58                 return 0;
  59         }
  60         krb5_init_ets(krb_context);
  61
  62         return 1;
  63 }
  64
  65 /* Check if this user is OK to login. This only works with krb5 - other
  66  * GSSAPI mechanisms will need their own.
  67  * Returns true if the user is OK to log in, otherwise returns 0
  68  */
  69
  70 static int
  71 ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name)
  72 {
  73         krb5_principal princ;
  74         int retval;
  75
  76         if (ssh_gssapi_krb5_init() == 0)
  77                 return 0;
  78
  79         if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
  80             &princ))) {
  81                 logit("krb5_parse_name(): %.100s",
  82                     krb5_get_err_text(krb_context, retval));
  83                 return 0;
  84         }
  85         if (krb5_kuserok(krb_context, princ, name)) {
  86                 retval = 1;
  87                 logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
  88                     name, (char *)client->displayname.value);
  89         } else
  90                 retval = 0;
  91
  92         krb5_free_principal(krb_context, princ);
  93         return retval;
  94 }
  95
  96
  97 /* This writes out any forwarded credentials from the structure populated
  98  * during userauth. Called after we have setuid to the user */
  99
 100 static void
 101 ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
 102 {
 103         krb5_ccache ccache;
 104         krb5_error_code problem;
 105         krb5_principal princ;
 106         OM_uint32 maj_status, min_status;
 107
 108         if (client->creds == NULL) {
 109                 debug("No credentials stored");
 110                 return;
 111         }
 112
 113         if (ssh_gssapi_krb5_init() == 0)
 114                 return;
 115
 116         if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
 117                 logit("krb5_cc_gen_new(): %.100s",
 118                     krb5_get_err_text(krb_context, problem));
 119                 return;
 120         }
 121
 122         if ((problem = krb5_parse_name(krb_context,
 123             client->exportedname.value, &princ))) {
 124                 logit("krb5_parse_name(): %.100s",
 125                     krb5_get_err_text(krb_context, problem));
 126                 krb5_cc_destroy(krb_context, ccache);
 127                 return;
 128         }
 129
 130         if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
 131                 logit("krb5_cc_initialize(): %.100s",
 132                     krb5_get_err_text(krb_context, problem));
 133                 krb5_free_principal(krb_context, princ);
 134                 krb5_cc_destroy(krb_context, ccache);
 135                 return;
 136         }
 137
 138         krb5_free_principal(krb_context, princ);
 139
 140         if ((maj_status = gss_krb5_copy_ccache(&min_status,
 141             client->creds, ccache))) {
 142                 logit("gss_krb5_copy_ccache() failed");
 143                 krb5_cc_destroy(krb_context, ccache);
 144                 return;
 145         }
 146
 147         client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
 148         client->store.envvar = "KRB5CCNAME";
 149         client->store.envval = xstrdup(client->store.filename);
 150
 151         krb5_cc_close(krb_context, ccache);
 152
 153         return;
 154 }
 155
 156 ssh_gssapi_mech gssapi_kerberos_mech = {
 157         "toWM5Slw5Ew8Mqkay+al2g==",
 158         "Kerberos",
 159         {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
 160         NULL,
 161         &ssh_gssapi_krb5_userok,
 162         NULL,
 163         &ssh_gssapi_krb5_storecreds
 164 };
 165
 166 #endif /* KRB5 */
 167
 168 #endif /* GSSAPI */