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", NULL };
 127         struct MD5Context ctx;
 128         struct samr_Password *nt_hash;
 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         domain_sid = samdb_domain_sid(ntp_signdconn->ntp_signd->samdb);
 156         if (!domain_sid) {
 157                 talloc_free(tmp_ctx);
 158                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 159         }
 160
 161         /* The top bit is a 'key selector' */
 162         sid = dom_sid_add_rid(tmp_ctx, domain_sid, sign_request.key_id & 0x7FFFFFFF);
 163         if (!sid) {
 164                 talloc_free(tmp_ctx);
 165                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 166         }
 167
 168         ret = ldb_search_exp_fmt(ntp_signdconn->ntp_signd->samdb, tmp_ctx,
 169                                  &res, samdb_base_dn(ntp_signdconn->ntp_signd->samdb),
 170                                  LDB_SCOPE_SUBTREE, attrs, "(&(objectSid=%s)(objectClass=computer))",
 171                                  dom_sid_string(tmp_ctx, sid));
 172         if (ret != LDB_SUCCESS) {
 173                 DEBUG(2, ("Failed to search for SID %s in SAM for NTP signing: %s\n", dom_sid_string(tmp_ctx, sid),
 174                           ldb_errstring(ntp_signdconn->ntp_signd->samdb)));
 175                 talloc_free(tmp_ctx);
 176                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 177         }
 178
 179         if (res->count == 0) {
 180                 DEBUG(5, ("Failed to find SID %s in SAM for NTP signing\n", dom_sid_string(tmp_ctx, sid)));
 181         } else if (res->count != 1) {
 182                 DEBUG(1, ("Found SID %s %u times in SAM for NTP signing\n", dom_sid_string(tmp_ctx, sid), res->count));
 183                 talloc_free(tmp_ctx);
 184                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 185         }
 186
 187         nt_hash = samdb_result_hash(tmp_ctx, res->msgs[0], "unicodePwd");
 188         if (!nt_hash) {
 189                 DEBUG(1, ("No unicodePwd found on record of SID %s for NTP signing\n", dom_sid_string(tmp_ctx, sid)));
 190                 talloc_free(tmp_ctx);
 191                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 192         }
 193
 194         /* Generate the reply packet */
 195         signed_reply.version = 1;
 196         signed_reply.packet_id = sign_request.packet_id;
 197         signed_reply.op = SIGNING_SUCCESS;
 198         signed_reply.signed_packet = data_blob_talloc(tmp_ctx,
 199                                                       NULL,
 200                                                       sign_request.packet_to_sign.length + 20);
 201
 202         if (!signed_reply.signed_packet.data) {
 203                 talloc_free(tmp_ctx);
 204                 return signing_failure(ntp_signdconn, sign_request.packet_id);
 205         }
 206
 207         memcpy(signed_reply.signed_packet.data, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 208         SIVAL(signed_reply.signed_packet.data, sign_request.packet_to_sign.length, sign_request.key_id);
 209
 210         /* Sign the NTP response with the unicodePwd */
 211         MD5Init(&ctx);
 212         MD5Update(&ctx, nt_hash->hash, sizeof(nt_hash->hash));
 213         MD5Update(&ctx, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 214         MD5Final(signed_reply.signed_packet.data + sign_request.packet_to_sign.length + 4, &ctx);
 215
 216
 217         /* Place it into the packet for the wire */
 218         ndr_err = ndr_push_struct_blob(&output, tmp_ctx,
 219                                        lp_iconv_convenience(ntp_signdconn->ntp_signd->task->lp_ctx),
 220                                        &signed_reply,
 221                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
 222
 223         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 224                 DEBUG(1,("failed to push ntp error reply\n"));
 225                 talloc_free(tmp_ctx);
 226                 return ndr_map_error2ntstatus(ndr_err);
 227         }
 228
 229         wrapped_output = data_blob_talloc(ntp_signdconn, NULL, output.length + 4);
 230         if (!wrapped_output.data) {
 231                 talloc_free(tmp_ctx);
 232                 return NT_STATUS_NO_MEMORY;
 233         }
 234
 235         /* The 'wire' transport for this is wrapped with a 4 byte network byte order length */
 236         RSIVAL(wrapped_output.data, 0, output.length);
 237         memcpy(wrapped_output.data + 4, output.data, output.length);
 238
 239         status = packet_send(ntp_signdconn->packet, wrapped_output);
 240
 241         /* the call isn't needed any more */
 242         talloc_free(tmp_ctx);
 243         return status;
 244 }
 245
 246 /*
 247   receive some data on a NTP_SIGND connection
 248 */
 249 static void ntp_signd_recv_handler(struct stream_connection *conn, uint16_t flags)
 250 {
 251         struct ntp_signd_connection *ntp_signdconn = talloc_get_type(conn->private,
 252                                                              struct ntp_signd_connection);
 253         packet_recv(ntp_signdconn->packet);
 254 }
 255
 256 /*
 257   called on a tcp recv error
 258 */
 259 static void ntp_signd_recv_error(void *private, NTSTATUS status)
 260 {
 261         struct ntp_signd_connection *ntp_signdconn = talloc_get_type(private, struct ntp_signd_connection);
 262         ntp_signd_terminate_connection(ntp_signdconn, nt_errstr(status));
 263 }
 264
 265 /*
 266   called when we can write to a connection
 267 */
 268 static void ntp_signd_send(struct stream_connection *conn, uint16_t flags)
 269 {
 270         struct ntp_signd_connection *ntp_signdconn = talloc_get_type(conn->private,
 271                                                              struct ntp_signd_connection);
 272         packet_queue_run(ntp_signdconn->packet);
 273 }
 274
 275 /*
 276   called when we get a new connection
 277 */
 278 static void ntp_signd_accept(struct stream_connection *conn)
 279 {
 280         struct ntp_signd_server *ntp_signd = talloc_get_type(conn->private, struct ntp_signd_server);
 281         struct ntp_signd_connection *ntp_signdconn;
 282
 283         ntp_signdconn = talloc_zero(conn, struct ntp_signd_connection);
 284         if (!ntp_signdconn) {
 285                 stream_terminate_connection(conn, "ntp_signd_accept: out of memory");
 286                 return;
 287         }
 288         ntp_signdconn->conn      = conn;
 289         ntp_signdconn->ntp_signd         = ntp_signd;
 290         conn->private    = ntp_signdconn;
 291
 292         ntp_signdconn->packet = packet_init(ntp_signdconn);
 293         if (ntp_signdconn->packet == NULL) {
 294                 ntp_signd_terminate_connection(ntp_signdconn, "ntp_signd_accept: out of memory");
 295                 return;
 296         }
 297         packet_set_private(ntp_signdconn->packet, ntp_signdconn);
 298         packet_set_socket(ntp_signdconn->packet, conn->socket);
 299         packet_set_callback(ntp_signdconn->packet, ntp_signd_recv);
 300         packet_set_full_request(ntp_signdconn->packet, packet_full_request_u32);
 301         packet_set_error_handler(ntp_signdconn->packet, ntp_signd_recv_error);
 302         packet_set_event_context(ntp_signdconn->packet, conn->event.ctx);
 303         packet_set_fde(ntp_signdconn->packet, conn->event.fde);
 304         packet_set_serialise(ntp_signdconn->packet);
 305 }
 306
 307 static const struct stream_server_ops ntp_signd_stream_ops = {
 308         .name                   = "ntp_signd",
 309         .accept_connection      = ntp_signd_accept,
 310         .recv_handler           = ntp_signd_recv_handler,
 311         .send_handler           = ntp_signd_send
 312 };
 313
 314 /*
 315   startup the ntp_signd task
 316 */
 317 static void ntp_signd_task_init(struct task_server *task)
 318 {
 319         struct ntp_signd_server *ntp_signd;
 320         NTSTATUS status;
 321
 322         const struct model_ops *model_ops;
 323
 324         const char *address;
 325
 326         if (!directory_create_or_exist(lp_ntp_signd_socket_directory(task->lp_ctx), geteuid(), 0755)) {
 327                 char *error = talloc_asprintf(task, "Cannot create NTP signd pipe directory: %s",
 328                                               lp_ntp_signd_socket_directory(task->lp_ctx));
 329                 task_server_terminate(task,
 330                                       error);
 331                 return;
 332         }
 333
 334         /* within the ntp_signd task we want to be a single process, so
 335            ask for the single process model ops and pass these to the
 336            stream_setup_socket() call. */
 337         model_ops = process_model_byname("single");
 338         if (!model_ops) {
 339                 DEBUG(0,("Can't find 'single' process model_ops\n"));
 340                 return;
 341         }
 342
 343         task_server_set_title(task, "task[ntp_signd]");
 344
 345         ntp_signd = talloc(task, struct ntp_signd_server);
 346         if (ntp_signd == NULL) {
 347                 task_server_terminate(task, "ntp_signd: out of memory");
 348                 return;
 349         }
 350
 351         ntp_signd->task = task;
 352
 353         /* Must be system to get at the password hashes */
 354         ntp_signd->samdb = samdb_connect(ntp_signd, task->event_ctx, task->lp_ctx, system_session(ntp_signd, task->lp_ctx));
 355         if (ntp_signd->samdb == NULL) {
 356                 task_server_terminate(task, "ntp_signd failed to open samdb");
 357                 return;
 358         }
 359
 360         address = talloc_asprintf(ntp_signd, "%s/socket", lp_ntp_signd_socket_directory(task->lp_ctx));
 361
 362         status = stream_setup_socket(ntp_signd->task->event_ctx,
 363                                      ntp_signd->task->lp_ctx,
 364                                      model_ops,
 365                                      &ntp_signd_stream_ops,
 366                                      "unix", address, NULL,
 367                                      lp_socket_options(ntp_signd->task->lp_ctx),
 368                                      ntp_signd);
 369         if (!NT_STATUS_IS_OK(status)) {
 370                 DEBUG(0,("Failed to bind to %s - %s\n",
 371                          address, nt_errstr(status)));
 372                 return;
 373         }
 374
 375 }
 376
 377
 378 /* called at smbd startup - register ourselves as a server service */
 379 NTSTATUS server_service_ntp_signd_init(void)
 380 {
 381         return register_server_service("ntp_signd", ntp_signd_task_init);
 382 }