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.version = 1;
  78         signed_reply.op = SIGNING_FAILURE;
  79         signed_reply.packet_id = packet_id;
  80         signed_reply.signed_packet = data_blob(NULL, 0);
  81
  82         ndr_err = ndr_push_struct_blob(&reply, tmp_ctx,
  83                                        lp_iconv_convenience(ntp_signdconn->ntp_signd->task->lp_ctx),
  84                                        &signed_reply,
  85                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
  86
  87         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
  88                 DEBUG(1,("failed to push ntp error reply\n"));
  89                 talloc_free(tmp_ctx);
  90                 return ndr_map_error2ntstatus(ndr_err);
  91         }
  92
  93         blob = data_blob_talloc(ntp_signdconn, NULL, reply.length + 4);
  94         if (!blob.data) {
  95                 talloc_free(tmp_ctx);
  96                 return NT_STATUS_NO_MEMORY;
  97         }
  98
  99         RSIVAL(blob.data, 0, reply.length);
 100         memcpy(blob.data + 4, reply.data, reply.length);
 101
 102         status = packet_send(ntp_signdconn->packet, blob);
 103
 104         /* the call isn't needed any more */
 105         talloc_free(tmp_ctx);
 106
 107         return status;
 108 }
 109
 110 /*
 111   receive a full packet on a NTP_SIGND connection
 112 */
 113 static NTSTATUS ntp_signd_recv(void *private, DATA_BLOB wrapped_input)
 114 {
 115         struct ntp_signd_connection *ntp_signdconn = talloc_get_type(private,
 116                                                              struct ntp_signd_connection);
 117         NTSTATUS status = NT_STATUS_UNSUCCESSFUL;
 118         TALLOC_CTX *tmp_ctx = talloc_new(ntp_signdconn);
 119         DATA_BLOB input, output, wrapped_output;
 120         const struct dom_sid *domain_sid;
 121         struct dom_sid *sid;
 122         struct sign_request sign_request;
 123         struct signed_reply signed_reply;
 124         enum ndr_err_code ndr_err;
 125         struct ldb_result *res;
 126         const char *attrs[] = { "unicodePwd", "userAccountControl", NULL };
 127         struct MD5Context ctx;
 128         struct samr_Password *nt_hash;
 129         uint32_t user_account_control;
 130         int ret;
 131
 132         NT_STATUS_HAVE_NO_MEMORY(tmp_ctx);
 133
 134         talloc_steal(tmp_ctx, wrapped_input.data);
 135
 136         input = data_blob_const(wrapped_input.data + 4, wrapped_input.length - 4);
 137
 138         ndr_err = ndr_pull_struct_blob_all(&input, tmp_ctx,
 139                                            lp_iconv_convenience(ntp_signdconn->ntp_signd->task->lp_ctx),
 140                                            &sign_request,
 141                                            (ndr_pull_flags_fn_t)ndr_pull_sign_request);
 142
 143         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 144                 DEBUG(1,("failed to parse ntp signing request\n"));
 145                 dump_data(1, input.data, input.length);
 146                 return ndr_map_error2ntstatus(ndr_err);
 147         }
 148
 149         /* We need to implement 'check signature' and 'request server
 150          * to sign' operations at some point */
 151         if (sign_request.op != SIGN_TO_CLIENT) {
 152                 talloc_free(tmp_ctx);
 153                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 154         }
 155
 156         domain_sid = samdb_domain_sid(ntp_signdconn->ntp_signd->samdb);
 157         if (!domain_sid) {
 158                 talloc_free(tmp_ctx);
 159                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 160         }
 161
 162         /* The top bit is a 'key selector' */
 163         sid = dom_sid_add_rid(tmp_ctx, domain_sid, sign_request.key_id & 0x7FFFFFFF);
 164         if (!sid) {
 165                 talloc_free(tmp_ctx);
 166                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 167         }
 168
 169         ret = ldb_search_exp_fmt(ntp_signdconn->ntp_signd->samdb, tmp_ctx,
 170                                  &res, samdb_base_dn(ntp_signdconn->ntp_signd->samdb),
 171                                  LDB_SCOPE_SUBTREE, attrs, "(&(objectSid=%s)(objectClass=computer))",
 172                                  dom_sid_string(tmp_ctx, sid));
 173         if (ret != LDB_SUCCESS) {
 174                 DEBUG(2, ("Failed to search for SID %s in SAM for NTP signing: %s\n", dom_sid_string(tmp_ctx, sid),
 175                           ldb_errstring(ntp_signdconn->ntp_signd->samdb)));
 176                 talloc_free(tmp_ctx);
 177                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 178         }
 179
 180         if (res->count == 0) {
 181                 DEBUG(5, ("Failed to find SID %s in SAM for NTP signing\n", dom_sid_string(tmp_ctx, sid)));
 182         } else if (res->count != 1) {
 183                 DEBUG(1, ("Found SID %s %u times in SAM for NTP signing\n", dom_sid_string(tmp_ctx, sid), res->count));
 184                 talloc_free(tmp_ctx);
 185                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 186         }
 187
 188         user_account_control = ldb_msg_find_attr_as_uint(res->msgs[0], "userAccountControl", 0);
 189
 190         if (user_account_control & UF_ACCOUNTDISABLE) {
 191                 DEBUG(1, ("Account for SID [%s] is disabled\n", dom_sid_string(tmp_ctx, sid)));
 192                 talloc_free(tmp_ctx);
 193                 return NT_STATUS_ACCESS_DENIED;
 194         }
 195
 196         nt_hash = samdb_result_hash(tmp_ctx, res->msgs[0], "unicodePwd");
 197         if (!nt_hash) {
 198                 DEBUG(1, ("No unicodePwd found on record of SID %s for NTP signing\n", dom_sid_string(tmp_ctx, sid)));
 199                 talloc_free(tmp_ctx);
 200                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 201         }
 202
 203         /* Generate the reply packet */
 204         signed_reply.version = 1;
 205         signed_reply.packet_id = sign_request.packet_id;
 206         signed_reply.op = SIGNING_SUCCESS;
 207         signed_reply.signed_packet = data_blob_talloc(tmp_ctx,
 208                                                       NULL,
 209                                                       sign_request.packet_to_sign.length + 20);
 210
 211         if (!signed_reply.signed_packet.data) {
 212                 talloc_free(tmp_ctx);
 213                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 214         }
 215
 216         memcpy(signed_reply.signed_packet.data, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 217         SIVAL(signed_reply.signed_packet.data, sign_request.packet_to_sign.length, sign_request.key_id);
 218
 219         /* Sign the NTP response with the unicodePwd */
 220         MD5Init(&ctx);
 221         MD5Update(&ctx, nt_hash->hash, sizeof(nt_hash->hash));
 222         MD5Update(&ctx, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 223         MD5Final(signed_reply.signed_packet.data + sign_request.packet_to_sign.length + 4, &ctx);
 224
 225
 226         /* Place it into the packet for the wire */
 227         ndr_err = ndr_push_struct_blob(&output, tmp_ctx,
 228                                        lp_iconv_convenience(ntp_signdconn->ntp_signd->task->lp_ctx),
 229                                        &signed_reply,
 230                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
 231
 232         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 233                 DEBUG(1,("failed to push ntp error reply\n"));
 234                 talloc_free(tmp_ctx);
 235                 return ndr_map_error2ntstatus(ndr_err);
 236         }
 237
 238         wrapped_output = data_blob_talloc(ntp_signdconn, NULL, output.length + 4);
 239         if (!wrapped_output.data) {
 240                 talloc_free(tmp_ctx);
 241                 return NT_STATUS_NO_MEMORY;
 242         }
 243
 244         /* The 'wire' transport for this is wrapped with a 4 byte network byte order length */
 245         RSIVAL(wrapped_output.data, 0, output.length);
 246         memcpy(wrapped_output.data + 4, output.data, output.length);
 247
 248         status = packet_send(ntp_signdconn->packet, wrapped_output);
 249
 250         /* the call isn't needed any more */
 251         talloc_free(tmp_ctx);
 252         return status;
 253 }
 254
 255 /*
 256   receive some data on a NTP_SIGND connection
 257 */
 258 static void ntp_signd_recv_handler(struct stream_connection *conn, uint16_t flags)
 259 {
 260         struct ntp_signd_connection *ntp_signdconn = talloc_get_type(conn->private,
 261                                                              struct ntp_signd_connection);
 262         packet_recv(ntp_signdconn->packet);
 263 }
 264
 265 /*
 266   called on a tcp recv error
 267 */
 268 static void ntp_signd_recv_error(void *private, NTSTATUS status)
 269 {
 270         struct ntp_signd_connection *ntp_signdconn = talloc_get_type(private, struct ntp_signd_connection);
 271         ntp_signd_terminate_connection(ntp_signdconn, nt_errstr(status));
 272 }
 273
 274 /*
 275   called when we can write to a connection
 276 */
 277 static void ntp_signd_send(struct stream_connection *conn, uint16_t flags)
 278 {
 279         struct ntp_signd_connection *ntp_signdconn = talloc_get_type(conn->private,
 280                                                              struct ntp_signd_connection);
 281         packet_queue_run(ntp_signdconn->packet);
 282 }
 283
 284 /*
 285   called when we get a new connection
 286 */
 287 static void ntp_signd_accept(struct stream_connection *conn)
 288 {
 289         struct ntp_signd_server *ntp_signd = talloc_get_type(conn->private, struct ntp_signd_server);
 290         struct ntp_signd_connection *ntp_signdconn;
 291
 292         ntp_signdconn = talloc_zero(conn, struct ntp_signd_connection);
 293         if (!ntp_signdconn) {
 294                 stream_terminate_connection(conn, "ntp_signd_accept: out of memory");
 295                 return;
 296         }
 297         ntp_signdconn->conn      = conn;
 298         ntp_signdconn->ntp_signd         = ntp_signd;
 299         conn->private    = ntp_signdconn;
 300
 301         ntp_signdconn->packet = packet_init(ntp_signdconn);
 302         if (ntp_signdconn->packet == NULL) {
 303                 ntp_signd_terminate_connection(ntp_signdconn, "ntp_signd_accept: out of memory");
 304                 return;
 305         }
 306         packet_set_private(ntp_signdconn->packet, ntp_signdconn);
 307         packet_set_socket(ntp_signdconn->packet, conn->socket);
 308         packet_set_callback(ntp_signdconn->packet, ntp_signd_recv);
 309         packet_set_full_request(ntp_signdconn->packet, packet_full_request_u32);
 310         packet_set_error_handler(ntp_signdconn->packet, ntp_signd_recv_error);
 311         packet_set_event_context(ntp_signdconn->packet, conn->event.ctx);
 312         packet_set_fde(ntp_signdconn->packet, conn->event.fde);
 313         packet_set_serialise(ntp_signdconn->packet);
 314 }
 315
 316 static const struct stream_server_ops ntp_signd_stream_ops = {
 317         .name                   = "ntp_signd",
 318         .accept_connection      = ntp_signd_accept,
 319         .recv_handler           = ntp_signd_recv_handler,
 320         .send_handler           = ntp_signd_send
 321 };
 322
 323 /*
 324   startup the ntp_signd task
 325 */
 326 static void ntp_signd_task_init(struct task_server *task)
 327 {
 328         struct ntp_signd_server *ntp_signd;
 329         NTSTATUS status;
 330
 331         const struct model_ops *model_ops;
 332
 333         const char *address;
 334
 335         if (!directory_create_or_exist(lp_ntp_signd_socket_directory(task->lp_ctx), geteuid(), 0755)) {
 336                 char *error = talloc_asprintf(task, "Cannot create NTP signd pipe directory: %s",
 337                                               lp_ntp_signd_socket_directory(task->lp_ctx));
 338                 task_server_terminate(task,
 339                                       error);
 340                 return;
 341         }
 342
 343         /* within the ntp_signd task we want to be a single process, so
 344            ask for the single process model ops and pass these to the
 345            stream_setup_socket() call. */
 346         model_ops = process_model_byname("single");
 347         if (!model_ops) {
 348                 DEBUG(0,("Can't find 'single' process model_ops\n"));
 349                 return;
 350         }
 351
 352         task_server_set_title(task, "task[ntp_signd]");
 353
 354         ntp_signd = talloc(task, struct ntp_signd_server);
 355         if (ntp_signd == NULL) {
 356                 task_server_terminate(task, "ntp_signd: out of memory");
 357                 return;
 358         }
 359
 360         ntp_signd->task = task;
 361
 362         /* Must be system to get at the password hashes */
 363         ntp_signd->samdb = samdb_connect(ntp_signd, task->event_ctx, task->lp_ctx, system_session(ntp_signd, task->lp_ctx));
 364         if (ntp_signd->samdb == NULL) {
 365                 task_server_terminate(task, "ntp_signd failed to open samdb");
 366                 return;
 367         }
 368
 369         address = talloc_asprintf(ntp_signd, "%s/socket", lp_ntp_signd_socket_directory(task->lp_ctx));
 370
 371         status = stream_setup_socket(ntp_signd->task->event_ctx,
 372                                      ntp_signd->task->lp_ctx,
 373                                      model_ops,
 374                                      &ntp_signd_stream_ops,
 375                                      "unix", address, NULL,
 376                                      lp_socket_options(ntp_signd->task->lp_ctx),
 377                                      ntp_signd);
 378         if (!NT_STATUS_IS_OK(status)) {
 379                 DEBUG(0,("Failed to bind to %s - %s\n",
 380                          address, nt_errstr(status)));
 381                 return;
 382         }
 383
 384 }
 385
 386
 387 /* called at smbd startup - register ourselves as a server service */
 388 NTSTATUS server_service_ntp_signd_init(void)
 389 {
 390         return register_server_service("ntp_signd", ntp_signd_task_init);
 391 }