source4/ntp_signd/ntp_signd.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    NTP packet signing server
   5
   6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2005
   7    Copyright (C) Andrew Tridgell        2005
   8    Copyright (C) Stefan Metzmacher      2005
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  22 */
  23
  24 #include "includes.h"
  25 #include "smbd/service_task.h"
  26 #include "smbd/service.h"
  27 #include "smbd/service_stream.h"
  28 #include "smbd/process_model.h"
  29 #include "lib/stream/packet.h"
  30 #include "librpc/gen_ndr/ndr_ntp_signd.h"
  31 #include "param/param.h"
  32 #include "dsdb/samdb/samdb.h"
  33 #include "auth/auth.h"
  34 #include "libcli/security/security.h"
  35 #include "lib/ldb/include/ldb.h"
  36 #include "lib/ldb/include/ldb_errors.h"
  37 #include "../lib/crypto/md5.h"
  38 #include "system/passwd.h"
  39
  40 /*
  41   top level context structure for the ntp_signd server
  42 */
  43 struct ntp_signd_server {
  44         struct task_server *task;
  45         struct ldb_context *samdb;
  46 };
  47
  48 /*
  49   state of an open connection
  50 */
  51 struct ntp_signd_connection {
  52         /* stream connection we belong to */
  53         struct stream_connection *conn;
  54
  55         /* the ntp_signd_server the connection belongs to */
  56         struct ntp_signd_server *ntp_signd;
  57
  58         struct packet_context *packet;
  59 };
  60
  61 static void ntp_signd_terminate_connection(struct ntp_signd_connection *ntp_signdconn, const char *reason)
  62 {
  63         stream_terminate_connection(ntp_signdconn->conn, reason);
  64 }
  65
  66 static NTSTATUS signing_failure(struct ntp_signd_connection *ntp_signdconn,
  67                                 uint32_t packet_id)
  68 {
  69         NTSTATUS status;
  70         struct signed_reply signed_reply;
  71         TALLOC_CTX *tmp_ctx = talloc_new(ntp_signdconn);
  72         DATA_BLOB reply, blob;
  73         enum ndr_err_code ndr_err;
  74
  75         NT_STATUS_HAVE_NO_MEMORY(tmp_ctx);
  76
  77         signed_reply.op = SIGNING_FAILURE;
  78         signed_reply.packet_id = packet_id;
  79         signed_reply.signed_packet = data_blob(NULL, 0);
  80
  81         ndr_err = ndr_push_struct_blob(&reply, tmp_ctx,
  82                                        lp_iconv_convenience(ntp_signdconn->ntp_signd->task->lp_ctx),
  83                                        &signed_reply,
  84                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
  85
  86         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
  87                 DEBUG(1,("failed to push ntp error reply\n"));
  88                 talloc_free(tmp_ctx);
  89                 return ndr_map_error2ntstatus(ndr_err);
  90         }
  91
  92         blob = data_blob_talloc(ntp_signdconn, NULL, reply.length + 4);
  93         if (!blob.data) {
  94                 talloc_free(tmp_ctx);
  95                 return NT_STATUS_NO_MEMORY;
  96         }
  97
  98         RSIVAL(blob.data, 0, reply.length);
  99         memcpy(blob.data + 4, reply.data, reply.length);
 100
 101         status = packet_send(ntp_signdconn->packet, blob);
 102
 103         /* the call isn't needed any more */
 104         talloc_free(tmp_ctx);
 105
 106         return status;
 107 }
 108
 109 /*
 110   receive a full packet on a NTP_SIGND connection
 111 */
 112 static NTSTATUS ntp_signd_recv(void *private_data, DATA_BLOB wrapped_input)
 113 {
 114         struct ntp_signd_connection *ntp_signdconn = talloc_get_type(private_data,
 115                                                              struct ntp_signd_connection);
 116         NTSTATUS status = NT_STATUS_UNSUCCESSFUL;
 117         TALLOC_CTX *tmp_ctx = talloc_new(ntp_signdconn);
 118         DATA_BLOB input, output, wrapped_output;
 119         const struct dom_sid *domain_sid;
 120         struct dom_sid *sid;
 121         struct sign_request sign_request;
 122         struct signed_reply signed_reply;
 123         enum ndr_err_code ndr_err;
 124         struct ldb_result *res;
 125         const char *attrs[] = { "unicodePwd", "userAccountControl", "cn", NULL };
 126         struct MD5Context ctx;
 127         struct samr_Password *nt_hash;
 128         uint32_t user_account_control;
 129         int ret;
 130
 131         NT_STATUS_HAVE_NO_MEMORY(tmp_ctx);
 132
 133         talloc_steal(tmp_ctx, wrapped_input.data);
 134
 135         input = data_blob_const(wrapped_input.data + 4, wrapped_input.length - 4);
 136
 137         ndr_err = ndr_pull_struct_blob_all(&input, tmp_ctx,
 138                                            lp_iconv_convenience(ntp_signdconn->ntp_signd->task->lp_ctx),
 139                                            &sign_request,
 140                                            (ndr_pull_flags_fn_t)ndr_pull_sign_request);
 141
 142         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 143                 DEBUG(1,("failed to parse ntp signing request\n"));
 144                 dump_data(1, input.data, input.length);
 145                 return ndr_map_error2ntstatus(ndr_err);
 146         }
 147
 148         /* We need to implement 'check signature' and 'request server
 149          * to sign' operations at some point */
 150         if (sign_request.op != SIGN_TO_CLIENT) {
 151                 talloc_free(tmp_ctx);
 152                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 153         }
 154
 155         /* We need to implement 'check signature' and 'request server
 156          * to sign' operations at some point */
 157         if (sign_request.version != NTP_SIGND_PROTOCOL_VERSION_0) {
 158                 talloc_free(tmp_ctx);
 159                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 160         }
 161
 162         domain_sid = samdb_domain_sid(ntp_signdconn->ntp_signd->samdb);
 163         if (!domain_sid) {
 164                 talloc_free(tmp_ctx);
 165                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 166         }
 167
 168         /* The top bit is a 'key selector' */
 169         sid = dom_sid_add_rid(tmp_ctx, domain_sid, sign_request.key_id & 0x7FFFFFFF);
 170         if (!sid) {
 171                 talloc_free(tmp_ctx);
 172                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 173         }
 174
 175         ret = ldb_search(ntp_signdconn->ntp_signd->samdb, tmp_ctx,
 176                                  &res, samdb_base_dn(ntp_signdconn->ntp_signd->samdb),
 177                                  LDB_SCOPE_SUBTREE, attrs, "(&(objectSid=%s)(objectClass=user))",
 178                                  dom_sid_string(tmp_ctx, sid));
 179         if (ret != LDB_SUCCESS) {
 180                 DEBUG(2, ("Failed to search for SID %s in SAM for NTP signing: %s\n", dom_sid_string(tmp_ctx, sid),
 181                           ldb_errstring(ntp_signdconn->ntp_signd->samdb)));
 182                 talloc_free(tmp_ctx);
 183                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 184         }
 185
 186         if (res->count == 0) {
 187                 DEBUG(5, ("Failed to find SID %s in SAM for NTP signing\n", dom_sid_string(tmp_ctx, sid)));
 188         } else if (res->count != 1) {
 189                 DEBUG(1, ("Found SID %s %u times in SAM for NTP signing\n", dom_sid_string(tmp_ctx, sid), res->count));
 190                 talloc_free(tmp_ctx);
 191                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 192         }
 193
 194         user_account_control = ldb_msg_find_attr_as_uint(res->msgs[0], "userAccountControl", 0);
 195
 196         if (user_account_control & UF_ACCOUNTDISABLE) {
 197                 DEBUG(1, ("Account %s for SID [%s] is disabled\n", ldb_dn_get_linearized(res->msgs[0]->dn), dom_sid_string(tmp_ctx, sid)));
 198                 talloc_free(tmp_ctx);
 199                 return NT_STATUS_ACCESS_DENIED;
 200         }
 201
 202         if (!(user_account_control & (UF_INTERDOMAIN_TRUST_ACCOUNT|UF_SERVER_TRUST_ACCOUNT|UF_WORKSTATION_TRUST_ACCOUNT))) {
 203                 DEBUG(1, ("Account %s for SID [%s] is not a trust account\n", ldb_dn_get_linearized(res->msgs[0]->dn), dom_sid_string(tmp_ctx, sid)));
 204                 talloc_free(tmp_ctx);
 205                 return NT_STATUS_ACCESS_DENIED;
 206         }
 207
 208         nt_hash = samdb_result_hash(tmp_ctx, res->msgs[0], "unicodePwd");
 209         if (!nt_hash) {
 210                 DEBUG(1, ("No unicodePwd found on record of SID %s for NTP signing\n", dom_sid_string(tmp_ctx, sid)));
 211                 talloc_free(tmp_ctx);
 212                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 213         }
 214
 215         /* Generate the reply packet */
 216         signed_reply.packet_id = sign_request.packet_id;
 217         signed_reply.op = SIGNING_SUCCESS;
 218         signed_reply.signed_packet = data_blob_talloc(tmp_ctx,
 219                                                       NULL,
 220                                                       sign_request.packet_to_sign.length + 20);
 221
 222         if (!signed_reply.signed_packet.data) {
 223                 talloc_free(tmp_ctx);
 224                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 225         }
 226
 227         memcpy(signed_reply.signed_packet.data, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 228         SIVAL(signed_reply.signed_packet.data, sign_request.packet_to_sign.length, sign_request.key_id);
 229
 230         /* Sign the NTP response with the unicodePwd */
 231         MD5Init(&ctx);
 232         MD5Update(&ctx, nt_hash->hash, sizeof(nt_hash->hash));
 233         MD5Update(&ctx, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 234         MD5Final(signed_reply.signed_packet.data + sign_request.packet_to_sign.length + 4, &ctx);
 235
 236
 237         /* Place it into the packet for the wire */
 238         ndr_err = ndr_push_struct_blob(&output, tmp_ctx,
 239                                        lp_iconv_convenience(ntp_signdconn->ntp_signd->task->lp_ctx),
 240                                        &signed_reply,
 241                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
 242
 243         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 244                 DEBUG(1,("failed to push ntp error reply\n"));
 245                 talloc_free(tmp_ctx);
 246                 return ndr_map_error2ntstatus(ndr_err);
 247         }
 248
 249         wrapped_output = data_blob_talloc(ntp_signdconn, NULL, output.length + 4);
 250         if (!wrapped_output.data) {
 251                 talloc_free(tmp_ctx);
 252                 return NT_STATUS_NO_MEMORY;
 253         }
 254
 255         /* The 'wire' transport for this is wrapped with a 4 byte network byte order length */
 256         RSIVAL(wrapped_output.data, 0, output.length);
 257         memcpy(wrapped_output.data + 4, output.data, output.length);
 258
 259         status = packet_send(ntp_signdconn->packet, wrapped_output);
 260
 261         /* the call isn't needed any more */
 262         talloc_free(tmp_ctx);
 263         return status;
 264 }
 265
 266 /*
 267   receive some data on a NTP_SIGND connection
 268 */
 269 static void ntp_signd_recv_handler(struct stream_connection *conn, uint16_t flags)
 270 {
 271         struct ntp_signd_connection *ntp_signdconn = talloc_get_type(conn->private_data,
 272                                                              struct ntp_signd_connection);
 273         packet_recv(ntp_signdconn->packet);
 274 }
 275
 276 /*
 277   called on a tcp recv error
 278 */
 279 static void ntp_signd_recv_error(void *private_data, NTSTATUS status)
 280 {
 281         struct ntp_signd_connection *ntp_signdconn = talloc_get_type(private_data, struct ntp_signd_connection);
 282         ntp_signd_terminate_connection(ntp_signdconn, nt_errstr(status));
 283 }
 284
 285 /*
 286   called when we can write to a connection
 287 */
 288 static void ntp_signd_send(struct stream_connection *conn, uint16_t flags)
 289 {
 290         struct ntp_signd_connection *ntp_signdconn = talloc_get_type(conn->private_data,
 291                                                              struct ntp_signd_connection);
 292         packet_queue_run(ntp_signdconn->packet);
 293 }
 294
 295 /*
 296   called when we get a new connection
 297 */
 298 static void ntp_signd_accept(struct stream_connection *conn)
 299 {
 300         struct ntp_signd_server *ntp_signd = talloc_get_type(conn->private_data, struct ntp_signd_server);
 301         struct ntp_signd_connection *ntp_signdconn;
 302
 303         ntp_signdconn = talloc_zero(conn, struct ntp_signd_connection);
 304         if (!ntp_signdconn) {
 305                 stream_terminate_connection(conn, "ntp_signd_accept: out of memory");
 306                 return;
 307         }
 308         ntp_signdconn->conn      = conn;
 309         ntp_signdconn->ntp_signd         = ntp_signd;
 310         conn->private_data    = ntp_signdconn;
 311
 312         ntp_signdconn->packet = packet_init(ntp_signdconn);
 313         if (ntp_signdconn->packet == NULL) {
 314                 ntp_signd_terminate_connection(ntp_signdconn, "ntp_signd_accept: out of memory");
 315                 return;
 316         }
 317         packet_set_private(ntp_signdconn->packet, ntp_signdconn);
 318         packet_set_socket(ntp_signdconn->packet, conn->socket);
 319         packet_set_callback(ntp_signdconn->packet, ntp_signd_recv);
 320         packet_set_full_request(ntp_signdconn->packet, packet_full_request_u32);
 321         packet_set_error_handler(ntp_signdconn->packet, ntp_signd_recv_error);
 322         packet_set_event_context(ntp_signdconn->packet, conn->event.ctx);
 323         packet_set_fde(ntp_signdconn->packet, conn->event.fde);
 324         packet_set_serialise(ntp_signdconn->packet);
 325 }
 326
 327 static const struct stream_server_ops ntp_signd_stream_ops = {
 328         .name                   = "ntp_signd",
 329         .accept_connection      = ntp_signd_accept,
 330         .recv_handler           = ntp_signd_recv_handler,
 331         .send_handler           = ntp_signd_send
 332 };
 333
 334 /*
 335   startup the ntp_signd task
 336 */
 337 static void ntp_signd_task_init(struct task_server *task)
 338 {
 339         struct ntp_signd_server *ntp_signd;
 340         NTSTATUS status;
 341
 342         const struct model_ops *model_ops;
 343
 344         const char *address;
 345
 346         if (!directory_create_or_exist(lp_ntp_signd_socket_directory(task->lp_ctx), geteuid(), 0755)) {
 347                 char *error = talloc_asprintf(task, "Cannot create NTP signd pipe directory: %s",
 348                                               lp_ntp_signd_socket_directory(task->lp_ctx));
 349                 task_server_terminate(task,
 350                                       error, true);
 351                 return;
 352         }
 353
 354         /* within the ntp_signd task we want to be a single process, so
 355            ask for the single process model ops and pass these to the
 356            stream_setup_socket() call. */
 357         model_ops = process_model_startup(task->event_ctx, "single");
 358         if (!model_ops) {
 359                 DEBUG(0,("Can't find 'single' process model_ops\n"));
 360                 return;
 361         }
 362
 363         task_server_set_title(task, "task[ntp_signd]");
 364
 365         ntp_signd = talloc(task, struct ntp_signd_server);
 366         if (ntp_signd == NULL) {
 367                 task_server_terminate(task, "ntp_signd: out of memory", true);
 368                 return;
 369         }
 370
 371         ntp_signd->task = task;
 372
 373         /* Must be system to get at the password hashes */
 374         ntp_signd->samdb = samdb_connect(ntp_signd, task->event_ctx, task->lp_ctx, system_session(task->lp_ctx));
 375         if (ntp_signd->samdb == NULL) {
 376                 task_server_terminate(task, "ntp_signd failed to open samdb", true);
 377                 return;
 378         }
 379
 380         address = talloc_asprintf(ntp_signd, "%s/socket", lp_ntp_signd_socket_directory(task->lp_ctx));
 381
 382         status = stream_setup_socket(ntp_signd->task->event_ctx,
 383                                      ntp_signd->task->lp_ctx,
 384                                      model_ops,
 385                                      &ntp_signd_stream_ops,
 386                                      "unix", address, NULL,
 387                                      lp_socket_options(ntp_signd->task->lp_ctx),
 388                                      ntp_signd);
 389         if (!NT_STATUS_IS_OK(status)) {
 390                 DEBUG(0,("Failed to bind to %s - %s\n",
 391                          address, nt_errstr(status)));
 392                 return;
 393         }
 394
 395 }
 396
 397
 398 /* called at smbd startup - register ourselves as a server service */
 399 NTSTATUS server_service_ntp_signd_init(void)
 400 {
 401         return register_server_service("ntp_signd", ntp_signd_task_init);
 402 }