source3/libads/kerberos_verify.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    kerberos utility library
   4    Copyright (C) Andrew Tridgell 2001
   5    Copyright (C) Remus Koos 2001
   6    Copyright (C) Luke Howard 2003
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23 #include "includes.h"
  24
  25 #ifdef HAVE_KRB5
  26
  27 /*
  28   verify an incoming ticket and parse out the principal name and
  29   authorization_data if available
  30 */
  31 NTSTATUS ads_verify_ticket(const char *realm, const DATA_BLOB *ticket,
  32                            char **principal, DATA_BLOB *auth_data,
  33                            DATA_BLOB *ap_rep,
  34                            uint8 session_key[16])
  35 {
  36         NTSTATUS sret = NT_STATUS_LOGON_FAILURE;
  37         krb5_context context = NULL;
  38         krb5_auth_context auth_context = NULL;
  39         krb5_keytab keytab = NULL;
  40         krb5_data packet;
  41         krb5_ticket *tkt = NULL;
  42         krb5_rcache rcache = NULL;
  43         int ret, i;
  44         krb5_keyblock *key = NULL;
  45         krb5_principal host_princ;
  46         char *host_princ_s = NULL;
  47         fstring myname;
  48         char *password_s = NULL;
  49         krb5_data password;
  50         krb5_enctype *enctypes = NULL;
  51 #if 0
  52         krb5_address local_addr;
  53         krb5_address remote_addr;
  54 #endif
  55         BOOL auth_ok = False;
  56
  57         ZERO_STRUCT(packet);
  58         ZERO_STRUCT(password);
  59         ZERO_STRUCTP(auth_data);
  60         ZERO_STRUCTP(ap_rep);
  61
  62         if (!secrets_init()) {
  63                 DEBUG(1,("ads_verify_ticket: secrets_init failed\n"));
  64                 return NT_STATUS_LOGON_FAILURE;
  65         }
  66
  67         password_s = secrets_fetch_machine_password(lp_workgroup(), NULL, NULL);
  68         if (!password_s) {
  69                 DEBUG(1,("ads_verify_ticket: failed to fetch machine password\n"));
  70                 return NT_STATUS_LOGON_FAILURE;
  71         }
  72
  73         password.data = password_s;
  74         password.length = strlen(password_s);
  75
  76         ret = krb5_init_context(&context);
  77         if (ret) {
  78                 DEBUG(1,("ads_verify_ticket: krb5_init_context failed (%s)\n", error_message(ret)));
  79                 return NT_STATUS_LOGON_FAILURE;
  80         }
  81
  82         ret = krb5_set_default_realm(context, realm);
  83         if (ret) {
  84                 DEBUG(1,("ads_verify_ticket: krb5_set_default_realm failed (%s)\n", error_message(ret)));
  85                 sret = NT_STATUS_LOGON_FAILURE;
  86                 goto out;
  87         }
  88
  89         /* This whole process is far more complex than I would
  90            like. We have to go through all this to allow us to store
  91            the secret internally, instead of using /etc/krb5.keytab */
  92
  93         ret = krb5_auth_con_init(context, &auth_context);
  94         if (ret) {
  95                 DEBUG(1,("ads_verify_ticket: krb5_auth_con_init failed (%s)\n", error_message(ret)));
  96                 sret = NT_STATUS_LOGON_FAILURE;
  97                 goto out;
  98         }
  99
 100         fstrcpy(myname, global_myname());
 101         strlower_m(myname);
 102         asprintf(&host_princ_s, "HOST/%s@%s", myname, lp_realm());
 103         ret = krb5_parse_name(context, host_princ_s, &host_princ);
 104         if (ret) {
 105                 DEBUG(1,("ads_verify_ticket: krb5_parse_name(%s) failed (%s)\n",
 106                                         host_princ_s, error_message(ret)));
 107                 sret = NT_STATUS_LOGON_FAILURE;
 108                 goto out;
 109         }
 110
 111         /*
 112          * JRA. We must set the rcache here. This will prevent replay attacks.
 113          */
 114
 115         ret = krb5_get_server_rcache(context, krb5_princ_component(context, host_princ, 0), &rcache);
 116         if (ret) {
 117                 DEBUG(1,("ads_verify_ticket: krb5_get_server_rcache failed (%s)\n", error_message(ret)));
 118                 sret = NT_STATUS_LOGON_FAILURE;
 119                 goto out;
 120         }
 121
 122         ret = krb5_auth_con_setrcache(context, auth_context, rcache);
 123         if (ret) {
 124                 DEBUG(1,("ads_verify_ticket: krb5_auth_con_setrcache failed (%s)\n", error_message(ret)));
 125                 sret = NT_STATUS_LOGON_FAILURE;
 126                 goto out;
 127         }
 128
 129         /* CIFS doesn't use addresses in tickets. This would breat NAT. JRA */
 130
 131         if ((ret = get_kerberos_allowed_etypes(context, &enctypes))) {
 132                 DEBUG(1,("ads_verify_ticket: krb5_get_permitted_enctypes failed (%s)\n",
 133                          error_message(ret)));
 134                 sret = NT_STATUS_LOGON_FAILURE;
 135                 goto out;
 136         }
 137
 138         /* Lock a mutex surrounding the replay as there is no locking in the MIT krb5
 139          * code surrounding the replay cache... */
 140
 141         if (!grab_server_mutex("replay cache mutex")) {
 142                 DEBUG(1,("ads_verify_ticket: unable to protect replay cache with mutex.\n"));
 143                 sret = NT_STATUS_LOGON_FAILURE;
 144                 goto out;
 145         }
 146
 147         /* We need to setup a auth context with each possible encoding type in turn. */
 148         for (i=0;enctypes[i];i++) {
 149                 if (!(key = (krb5_keyblock *)malloc(sizeof(*key)))) {
 150                         sret = NT_STATUS_NO_MEMORY;
 151                         goto out;
 152                 }
 153
 154                 if (create_kerberos_key_from_string(context, host_princ, &password, key, enctypes[i])) {
 155                         continue;
 156                 }
 157
 158                 krb5_auth_con_setuseruserkey(context, auth_context, key);
 159
 160                 krb5_free_keyblock(context, key);
 161
 162                 packet.length = ticket->length;
 163                 packet.data = (krb5_pointer)ticket->data;
 164
 165                 if (!(ret = krb5_rd_req(context, &auth_context, &packet,
 166                                        NULL, keytab, NULL, &tkt))) {
 167                         DEBUG(10,("ads_verify_ticket: enc type [%u] decrypted message !\n",
 168                                 (unsigned int)enctypes[i] ));
 169                         auth_ok = True;
 170                         break;
 171                 }
 172
 173                 DEBUG((ret != KRB5_BAD_ENCTYPE) ? 3 : 10,
 174                                 ("ads_verify_ticket: enc type [%u] failed to decrypt with error %s\n",
 175                                 (unsigned int)enctypes[i], error_message(ret)));
 176         }
 177
 178         release_server_mutex();
 179
 180         if (!auth_ok) {
 181                 DEBUG(3,("ads_verify_ticket: krb5_rd_req with auth failed (%s)\n",
 182                          error_message(ret)));
 183                 sret = NT_STATUS_LOGON_FAILURE;
 184                 goto out;
 185         }
 186
 187         ret = krb5_mk_rep(context, auth_context, &packet);
 188         if (ret) {
 189                 DEBUG(3,("ads_verify_ticket: Failed to generate mutual authentication reply (%s)\n",
 190                         error_message(ret)));
 191                 sret = NT_STATUS_LOGON_FAILURE;
 192                 goto out;
 193         }
 194
 195         *ap_rep = data_blob(packet.data, packet.length);
 196         free(packet.data);
 197
 198         get_krb5_smb_session_key(context, auth_context, session_key, True);
 199 #ifdef DEBUG_PASSWORD
 200         DEBUG(10,("SMB session key (from ticket) follows:\n"));
 201         dump_data(10, session_key, 16);
 202 #endif
 203
 204 #if 0
 205         file_save("/tmp/ticket.dat", ticket->data, ticket->length);
 206 #endif
 207
 208         get_auth_data_from_tkt(auth_data, tkt);
 209
 210         {
 211                 TALLOC_CTX *ctx = talloc_init("pac data");
 212                 decode_pac_data(auth_data, ctx);
 213                 talloc_destroy(ctx);
 214         }
 215
 216 #if 0
 217         if (tkt->enc_part2) {
 218                 file_save("/tmp/authdata.dat",
 219                           tkt->enc_part2->authorization_data[0]->contents,
 220                           tkt->enc_part2->authorization_data[0]->length);
 221 #endif
 222
 223         if ((ret = krb5_unparse_name(context, get_principal_from_tkt(tkt),
 224                                      principal))) {
 225                 DEBUG(3,("ads_verify_ticket: krb5_unparse_name failed (%s)\n",
 226                          error_message(ret)));
 227                 sret = NT_STATUS_LOGON_FAILURE;
 228                 goto out;
 229         }
 230
 231         sret = NT_STATUS_OK;
 232
 233  out:
 234
 235         if (!NT_STATUS_IS_OK(sret))
 236                 data_blob_free(auth_data);
 237
 238         if (!NT_STATUS_IS_OK(sret))
 239                 data_blob_free(ap_rep);
 240
 241         krb5_free_principal(context, host_princ);
 242         if (tkt != NULL)
 243                 krb5_free_ticket(context, tkt);
 244         free_kerberos_etypes(context, enctypes);
 245         SAFE_FREE(password_s);
 246         SAFE_FREE(host_princ_s);
 247
 248         if (auth_context)
 249                 krb5_auth_con_free(context, auth_context);
 250
 251         if (context)
 252                 krb5_free_context(context);
 253
 254         return sret;
 255 }
 256
 257 #endif /* HAVE_KRB5 */