source4/kdc/kpasswd-service.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Samba kpasswd implementation
   5
   6    Copyright (c) 2005      Andrew Bartlett <abartlet@samba.org>
   7    Copyright (c) 2016      Andreas Schneider <asn@samba.org>
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21 */
  22
  23 #include "includes.h"
  24 #include "smbd/service_task.h"
  25 #include "tsocket/tsocket.h"
  26 #include "auth/credentials/credentials.h"
  27 #include "auth/auth.h"
  28 #include "auth/gensec/gensec.h"
  29 #include "kdc/kdc-server.h"
  30 #include "kdc/kpasswd-service.h"
  31 #include "kdc/kpasswd-helper.h"
  32
  33 #define HEADER_LEN 6
  34 #ifndef RFC3244_VERSION
  35 #define RFC3244_VERSION 0xff80
  36 #endif
  37
  38 kdc_code kpasswd_process(struct kdc_server *kdc,
  39                          TALLOC_CTX *mem_ctx,
  40                          DATA_BLOB *request,
  41                          DATA_BLOB *reply,
  42                          struct tsocket_address *remote_addr,
  43                          struct tsocket_address *local_addr,
  44                          int datagram)
  45 {
  46         uint16_t len;
  47         uint16_t verno;
  48         uint16_t ap_req_len;
  49         uint16_t enc_data_len;
  50         DATA_BLOB ap_req_blob = data_blob_null;
  51         DATA_BLOB ap_rep_blob = data_blob_null;
  52         DATA_BLOB enc_data_blob = data_blob_null;
  53         DATA_BLOB dec_data_blob = data_blob_null;
  54         DATA_BLOB kpasswd_dec_reply = data_blob_null;
  55         const char *error_string = NULL;
  56         krb5_error_code error_code = 0;
  57         struct cli_credentials *server_credentials;
  58         struct gensec_security *gensec_security;
  59 #ifndef SAMBA4_USES_HEIMDAL
  60         struct sockaddr_storage remote_ss;
  61 #endif
  62         struct sockaddr_storage local_ss;
  63         ssize_t socklen;
  64         TALLOC_CTX *tmp_ctx;
  65         kdc_code rc = KDC_ERROR;
  66         krb5_error_code code = 0;
  67         NTSTATUS status;
  68         int rv;
  69         bool is_inet;
  70         bool ok;
  71
  72         if (kdc->am_rodc) {
  73                 return KDC_PROXY_REQUEST;
  74         }
  75
  76         tmp_ctx = talloc_new(mem_ctx);
  77         if (tmp_ctx == NULL) {
  78                 return KDC_ERROR;
  79         }
  80
  81         is_inet = tsocket_address_is_inet(remote_addr, "ip");
  82         if (!is_inet) {
  83                 DBG_WARNING("Invalid remote IP address");
  84                 goto done;
  85         }
  86
  87 #ifndef SAMBA4_USES_HEIMDAL
  88         /*
  89          * FIXME: Heimdal fails to to do a krb5_rd_req() in gensec_krb5 if we
  90          * set the remote address.
  91          */
  92
  93         /* remote_addr */
  94         socklen = tsocket_address_bsd_sockaddr(remote_addr,
  95                                                (struct sockaddr *)&remote_ss,
  96                                                sizeof(struct sockaddr_storage));
  97         if (socklen < 0) {
  98                 DBG_WARNING("Invalid remote IP address");
  99                 goto done;
 100         }
 101 #endif
 102
 103         /* local_addr */
 104         socklen = tsocket_address_bsd_sockaddr(local_addr,
 105                                                (struct sockaddr *)&local_ss,
 106                                                sizeof(struct sockaddr_storage));
 107         if (socklen < 0) {
 108                 DBG_WARNING("Invalid local IP address");
 109                 goto done;
 110         }
 111
 112         if (request->length <= HEADER_LEN) {
 113                 DBG_WARNING("Request truncated\n");
 114                 goto done;
 115         }
 116
 117         len = RSVAL(request->data, 0);
 118         if (request->length != len) {
 119                 DBG_WARNING("Request length does not match\n");
 120                 goto done;
 121         }
 122
 123         verno = RSVAL(request->data, 2);
 124         if (verno != 1 && verno != RFC3244_VERSION) {
 125                 DBG_WARNING("Unsupported version: 0x%04x\n", verno);
 126         }
 127
 128         ap_req_len = RSVAL(request->data, 4);
 129         if ((ap_req_len >= len) || ((ap_req_len + HEADER_LEN) >= len)) {
 130                 DBG_WARNING("AP_REQ truncated\n");
 131                 goto done;
 132         }
 133
 134         ap_req_blob = data_blob_const(&request->data[HEADER_LEN], ap_req_len);
 135
 136         enc_data_len = len - ap_req_len;
 137         enc_data_blob = data_blob_const(&request->data[HEADER_LEN + ap_req_len],
 138                                         enc_data_len);
 139
 140         server_credentials = cli_credentials_init(tmp_ctx);
 141         if (server_credentials == NULL) {
 142                 DBG_ERR("Failed to initialize server credentials!\n");
 143                 goto done;
 144         }
 145
 146         /*
 147          * We want the credentials subsystem to use the krb5 context we already
 148          * have, rather than a new context.
 149          *
 150          * On this context the KDB plugin has been loaded, so we can access
 151          * dsdb.
 152          */
 153         status = cli_credentials_set_krb5_context(server_credentials,
 154                                                   kdc->smb_krb5_context);
 155         if (!NT_STATUS_IS_OK(status)) {
 156                 goto done;
 157         }
 158
 159         cli_credentials_set_conf(server_credentials, kdc->task->lp_ctx);
 160
 161         ok = cli_credentials_set_username(server_credentials,
 162                                           "kadmin/changepw",
 163                                           CRED_SPECIFIED);
 164         if (!ok) {
 165                 goto done;
 166         }
 167
 168         rv = cli_credentials_set_keytab_name(server_credentials,
 169                                              kdc->task->lp_ctx,
 170                                              kdc->keytab_name,
 171                                              CRED_SPECIFIED);
 172         if (rv != 0) {
 173                 DBG_ERR("Failed to set credentials keytab name\n");
 174                 goto done;
 175         }
 176
 177         status = samba_server_gensec_start(tmp_ctx,
 178                                            kdc->task->event_ctx,
 179                                            kdc->task->msg_ctx,
 180                                            kdc->task->lp_ctx,
 181                                            server_credentials,
 182                                            "kpasswd",
 183                                            &gensec_security);
 184         if (!NT_STATUS_IS_OK(status)) {
 185                 goto done;
 186         }
 187
 188         status = gensec_set_local_address(gensec_security, local_addr);
 189         if (!NT_STATUS_IS_OK(status)) {
 190                 goto done;
 191         }
 192
 193 #ifndef SAMBA4_USES_HEIMDAL
 194         status = gensec_set_remote_address(gensec_security, remote_addr);
 195         if (!NT_STATUS_IS_OK(status)) {
 196                 goto done;
 197         }
 198 #endif
 199
 200         /* We want the GENSEC wrap calls to generate PRIV tokens */
 201         gensec_want_feature(gensec_security, GENSEC_FEATURE_SEAL);
 202
 203         /* Use the krb5 gesec mechanism so we can load DB modules */
 204         status = gensec_start_mech_by_name(gensec_security, "krb5");
 205         if (!NT_STATUS_IS_OK(status)) {
 206                 goto done;
 207         }
 208
 209         /*
 210          * Accept the AP-REQ and generate the AP-REP we need for the reply
 211          *
 212          * We only allow KRB5 and make sure the backend to is RPC/IPC free.
 213          *
 214          * See gensec_krb5_update_internal() as GENSEC_SERVER.
 215          *
 216          * It allows gensec_update() not to block.
 217          *
 218          * If that changes in future we need to use
 219          * gensec_update_send/recv here!
 220          */
 221         status = gensec_update(gensec_security, tmp_ctx,
 222                                ap_req_blob, &ap_rep_blob);
 223         if (!NT_STATUS_IS_OK(status) &&
 224             !NT_STATUS_EQUAL(status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
 225                 ap_rep_blob = data_blob_null;
 226                 error_code = KRB5_KPASSWD_HARDERROR;
 227                 error_string = talloc_asprintf(tmp_ctx,
 228                                                "gensec_update failed - %s\n",
 229                                                nt_errstr(status));
 230                 DBG_ERR("%s", error_string);
 231                 goto reply;
 232         }
 233
 234         status = gensec_unwrap(gensec_security,
 235                                tmp_ctx,
 236                                &enc_data_blob,
 237                                &dec_data_blob);
 238         if (!NT_STATUS_IS_OK(status)) {
 239                 ap_rep_blob = data_blob_null;
 240                 error_code = KRB5_KPASSWD_HARDERROR;
 241                 error_string = talloc_asprintf(tmp_ctx,
 242                                                "gensec_unwrap failed - %s\n",
 243                                                nt_errstr(status));
 244                 DBG_ERR("%s", error_string);
 245                 goto reply;
 246         }
 247
 248         code = kpasswd_handle_request(kdc,
 249                                       tmp_ctx,
 250                                       gensec_security,
 251                                       verno,
 252                                       &dec_data_blob,
 253                                       &kpasswd_dec_reply,
 254                                       &error_string);
 255         if (code != 0) {
 256                 error_code = code;
 257                 goto reply;
 258         }
 259
 260         status = gensec_wrap(gensec_security,
 261                              tmp_ctx,
 262                              &kpasswd_dec_reply,
 263                              &enc_data_blob);
 264         if (!NT_STATUS_IS_OK(status)) {
 265                 error_code = KRB5_KPASSWD_HARDERROR;
 266                 error_string = talloc_asprintf(tmp_ctx,
 267                                                "gensec_wrap failed - %s\n",
 268                                                nt_errstr(status));
 269                 DBG_ERR("%s", error_string);
 270                 goto reply;
 271         }
 272
 273 reply:
 274         if (error_code != 0) {
 275                 krb5_data k_enc_data;
 276                 krb5_data k_dec_data;
 277                 const char *principal_string;
 278                 krb5_principal server_principal;
 279
 280                 if (error_string == NULL) {
 281                         DBG_ERR("Invalid error string! This should not happen\n");
 282                         goto done;
 283                 }
 284
 285                 ok = kpasswd_make_error_reply(tmp_ctx,
 286                                               error_code,
 287                                               error_string,
 288                                               &dec_data_blob);
 289                 if (!ok) {
 290                         DBG_ERR("Failed to create error reply\n");
 291                         goto done;
 292                 }
 293
 294                 k_dec_data.length = dec_data_blob.length;
 295                 k_dec_data.data   = (char *)dec_data_blob.data;
 296
 297                 principal_string = cli_credentials_get_principal(server_credentials,
 298                                                                  tmp_ctx);
 299                 if (principal_string == NULL) {
 300                         goto done;
 301                 }
 302
 303                 code = smb_krb5_parse_name(kdc->smb_krb5_context->krb5_context,
 304                                            principal_string,
 305                                            &server_principal);
 306                 if (code != 0) {
 307                         DBG_ERR("Failed to create principal: %s\n",
 308                                 error_message(code));
 309                         goto done;
 310                 }
 311
 312                 code = smb_krb5_mk_error(kdc->smb_krb5_context->krb5_context,
 313                                          error_code,
 314                                          NULL, /* e_text */
 315                                          &k_dec_data,
 316                                          NULL, /* client */
 317                                          server_principal,
 318                                          &k_enc_data);
 319                 krb5_free_principal(kdc->smb_krb5_context->krb5_context,
 320                                     server_principal);
 321                 if (code != 0) {
 322                         DBG_ERR("Failed to create krb5 error reply: %s\n",
 323                                 error_message(code));
 324                         goto done;
 325                 }
 326
 327                 enc_data_blob = data_blob_talloc(tmp_ctx,
 328                                                  k_enc_data.data,
 329                                                  k_enc_data.length);
 330                 if (enc_data_blob.data == NULL) {
 331                         DBG_ERR("Failed to allocate memory for error reply\n");
 332                         goto done;
 333                 }
 334         }
 335
 336         *reply = data_blob_talloc(mem_ctx,
 337                                   NULL,
 338                                   HEADER_LEN + ap_rep_blob.length + enc_data_blob.length);
 339         if (reply->data == NULL) {
 340                 goto done;
 341         }
 342         RSSVAL(reply->data, 0, reply->length);
 343         RSSVAL(reply->data, 2, 1);
 344         RSSVAL(reply->data, 4, ap_rep_blob.length);
 345         memcpy(reply->data + HEADER_LEN,
 346                ap_rep_blob.data,
 347                ap_rep_blob.length);
 348         memcpy(reply->data + HEADER_LEN + ap_rep_blob.length,
 349                enc_data_blob.data,
 350                enc_data_blob.length);
 351
 352         rc = KDC_OK;
 353 done:
 354         talloc_free(tmp_ctx);
 355         return rc;
 356 }