source3/lib/messages_local.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Samba internal messaging functions
   4    Copyright (C) 2007 by Volker Lendecke
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 /**
  21   @defgroup messages Internal messaging framework
  22   @{
  23   @file messages.c
  24
  25   @brief  Module for internal messaging between Samba daemons.
  26
  27    The idea is that if a part of Samba wants to do communication with
  28    another Samba process then it will do a message_register() of a
  29    dispatch function, and use message_send_pid() to send messages to
  30    that process.
  31
  32    The dispatch function is given the pid of the sender, and it can
  33    use that to reply by message_send_pid().  See ping_message() for a
  34    simple example.
  35
  36    @caution Dispatch functions must be able to cope with incoming
  37    messages on an *odd* byte boundary.
  38
  39    This system doesn't have any inherent size limitations but is not
  40    very efficient for large messages or when messages are sent in very
  41    quick succession.
  42
  43 */
  44
  45 #include "includes.h"
  46 #include "librpc/gen_ndr/messaging.h"
  47 #include "librpc/gen_ndr/ndr_messaging.h"
  48
  49 struct messaging_tdb_context {
  50         struct messaging_context *msg_ctx;
  51         struct tdb_wrap *tdb;
  52         struct tevent_signal *se;
  53         int received_messages;
  54 };
  55
  56 static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
  57                                    struct server_id pid, int msg_type,
  58                                    const DATA_BLOB *data,
  59                                    struct messaging_backend *backend);
  60 static void message_dispatch(struct messaging_context *msg_ctx);
  61
  62 static void messaging_tdb_signal_handler(struct tevent_context *ev_ctx,
  63                                          struct tevent_signal *se,
  64                                          int signum, int count,
  65                                          void *_info, void *private_data)
  66 {
  67         struct messaging_tdb_context *ctx = talloc_get_type(private_data,
  68                                             struct messaging_tdb_context);
  69
  70         ctx->received_messages++;
  71
  72         DEBUG(10, ("messaging_tdb_signal_handler: sig[%d] count[%d] msgs[%d]\n",
  73                    signum, count, ctx->received_messages));
  74
  75         message_dispatch(ctx->msg_ctx);
  76 }
  77
  78 /****************************************************************************
  79  Initialise the messaging functions.
  80 ****************************************************************************/
  81
  82 NTSTATUS messaging_tdb_init(struct messaging_context *msg_ctx,
  83                             TALLOC_CTX *mem_ctx,
  84                             struct messaging_backend **presult)
  85 {
  86         struct messaging_backend *result;
  87         struct messaging_tdb_context *ctx;
  88
  89         if (!(result = TALLOC_P(mem_ctx, struct messaging_backend))) {
  90                 DEBUG(0, ("talloc failed\n"));
  91                 return NT_STATUS_NO_MEMORY;
  92         }
  93
  94         ctx = TALLOC_ZERO_P(result, struct messaging_tdb_context);
  95         if (!ctx) {
  96                 DEBUG(0, ("talloc failed\n"));
  97                 TALLOC_FREE(result);
  98                 return NT_STATUS_NO_MEMORY;
  99         }
 100         result->private_data = ctx;
 101         result->send_fn = messaging_tdb_send;
 102
 103         ctx->msg_ctx = msg_ctx;
 104
 105         ctx->tdb = tdb_wrap_open(ctx, lock_path("messages.tdb"), 0,
 106                                  TDB_CLEAR_IF_FIRST|TDB_DEFAULT|TDB_VOLATILE,
 107                                  O_RDWR|O_CREAT,0600);
 108
 109         if (!ctx->tdb) {
 110                 NTSTATUS status = map_nt_error_from_unix(errno);
 111                 DEBUG(0, ("ERROR: Failed to initialise messages database: "
 112                           "%s\n", strerror(errno)));
 113                 TALLOC_FREE(result);
 114                 return status;
 115         }
 116
 117         ctx->se = tevent_add_signal(msg_ctx->event_ctx,
 118                                     ctx,
 119                                     SIGUSR1, 0,
 120                                     messaging_tdb_signal_handler,
 121                                     ctx);
 122         if (!ctx->se) {
 123                 NTSTATUS status = map_nt_error_from_unix(errno);
 124                 DEBUG(0, ("ERROR: Failed to initialise messages signal handler: "
 125                           "%s\n", strerror(errno)));
 126                 TALLOC_FREE(result);
 127                 return status;
 128         }
 129
 130         sec_init();
 131
 132         *presult = result;
 133         return NT_STATUS_OK;
 134 }
 135
 136 bool messaging_tdb_parent_init(void)
 137 {
 138         struct tdb_wrap *db;
 139
 140         /*
 141          * Open the tdb in the parent process (smbd) so that our
 142          * CLEAR_IF_FIRST optimization in tdb_reopen_all can properly
 143          * work.
 144          */
 145
 146         db = tdb_wrap_open(talloc_autofree_context(),
 147                            lock_path("messages.tdb"), 0,
 148                            TDB_CLEAR_IF_FIRST|TDB_DEFAULT|TDB_VOLATILE,
 149                            O_RDWR|O_CREAT,0600);
 150         if (db == NULL) {
 151                 DEBUG(1, ("could not open messaging.tdb: %s\n",
 152                           strerror(errno)));
 153                 return false;
 154         }
 155         return true;
 156 }
 157
 158 /*******************************************************************
 159  Form a static tdb key from a pid.
 160 ******************************************************************/
 161
 162 static TDB_DATA message_key_pid(TALLOC_CTX *mem_ctx, struct server_id pid)
 163 {
 164         char *key;
 165         TDB_DATA kbuf;
 166
 167         key = talloc_asprintf(talloc_tos(), "PID/%s", procid_str_static(&pid));
 168
 169         SMB_ASSERT(key != NULL);
 170
 171         kbuf.dptr = (uint8 *)key;
 172         kbuf.dsize = strlen(key)+1;
 173         return kbuf;
 174 }
 175
 176 /*
 177   Fetch the messaging array for a process
 178  */
 179
 180 static NTSTATUS messaging_tdb_fetch(TDB_CONTEXT *msg_tdb,
 181                                     TDB_DATA key,
 182                                     TALLOC_CTX *mem_ctx,
 183                                     struct messaging_array **presult)
 184 {
 185         struct messaging_array *result;
 186         TDB_DATA data;
 187         DATA_BLOB blob;
 188         enum ndr_err_code ndr_err;
 189
 190         if (!(result = TALLOC_ZERO_P(mem_ctx, struct messaging_array))) {
 191                 return NT_STATUS_NO_MEMORY;
 192         }
 193
 194         data = tdb_fetch(msg_tdb, key);
 195
 196         if (data.dptr == NULL) {
 197                 *presult = result;
 198                 return NT_STATUS_OK;
 199         }
 200
 201         blob = data_blob_const(data.dptr, data.dsize);
 202
 203         ndr_err = ndr_pull_struct_blob(
 204                 &blob, result, NULL, result,
 205                 (ndr_pull_flags_fn_t)ndr_pull_messaging_array);
 206
 207         SAFE_FREE(data.dptr);
 208
 209         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 210                 TALLOC_FREE(result);
 211                 return ndr_map_error2ntstatus(ndr_err);
 212         }
 213
 214         if (DEBUGLEVEL >= 10) {
 215                 DEBUG(10, ("messaging_tdb_fetch:\n"));
 216                 NDR_PRINT_DEBUG(messaging_array, result);
 217         }
 218
 219         *presult = result;
 220         return NT_STATUS_OK;
 221 }
 222
 223 /*
 224   Store a messaging array for a pid
 225 */
 226
 227 static NTSTATUS messaging_tdb_store(TDB_CONTEXT *msg_tdb,
 228                                     TDB_DATA key,
 229                                     struct messaging_array *array)
 230 {
 231         TDB_DATA data;
 232         DATA_BLOB blob;
 233         enum ndr_err_code ndr_err;
 234         TALLOC_CTX *mem_ctx;
 235         int ret;
 236
 237         if (array->num_messages == 0) {
 238                 tdb_delete(msg_tdb, key);
 239                 return NT_STATUS_OK;
 240         }
 241
 242         if (!(mem_ctx = talloc_new(array))) {
 243                 return NT_STATUS_NO_MEMORY;
 244         }
 245
 246         ndr_err = ndr_push_struct_blob(
 247                 &blob, mem_ctx, NULL, array,
 248                 (ndr_push_flags_fn_t)ndr_push_messaging_array);
 249
 250         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 251                 talloc_free(mem_ctx);
 252                 return ndr_map_error2ntstatus(ndr_err);
 253         }
 254
 255         if (DEBUGLEVEL >= 10) {
 256                 DEBUG(10, ("messaging_tdb_store:\n"));
 257                 NDR_PRINT_DEBUG(messaging_array, array);
 258         }
 259
 260         data.dptr = blob.data;
 261         data.dsize = blob.length;
 262
 263         ret = tdb_store(msg_tdb, key, data, TDB_REPLACE);
 264         TALLOC_FREE(mem_ctx);
 265
 266         return (ret == 0) ? NT_STATUS_OK : NT_STATUS_INTERNAL_DB_CORRUPTION;
 267 }
 268
 269 /****************************************************************************
 270  Notify a process that it has a message. If the process doesn't exist
 271  then delete its record in the database.
 272 ****************************************************************************/
 273
 274 static NTSTATUS message_notify(struct server_id procid)
 275 {
 276         pid_t pid = procid.pid;
 277         int ret;
 278         uid_t euid = geteuid();
 279
 280         /*
 281          * Doing kill with a non-positive pid causes messages to be
 282          * sent to places we don't want.
 283          */
 284
 285         SMB_ASSERT(pid > 0);
 286
 287         if (euid != 0) {
 288                 /* If we're not root become so to send the message. */
 289                 save_re_uid();
 290                 set_effective_uid(0);
 291         }
 292
 293         ret = kill(pid, SIGUSR1);
 294
 295         if (euid != 0) {
 296                 /* Go back to who we were. */
 297                 int saved_errno = errno;
 298                 restore_re_uid_fromroot();
 299                 errno = saved_errno;
 300         }
 301
 302         if (ret == 0) {
 303                 return NT_STATUS_OK;
 304         }
 305
 306         /*
 307          * Something has gone wrong
 308          */
 309
 310         DEBUG(2,("message to process %d failed - %s\n", (int)pid,
 311                  strerror(errno)));
 312
 313         /*
 314          * No call to map_nt_error_from_unix -- don't want to link in
 315          * errormap.o into lots of utils.
 316          */
 317
 318         if (errno == ESRCH)  return NT_STATUS_INVALID_HANDLE;
 319         if (errno == EINVAL) return NT_STATUS_INVALID_PARAMETER;
 320         if (errno == EPERM)  return NT_STATUS_ACCESS_DENIED;
 321         return NT_STATUS_UNSUCCESSFUL;
 322 }
 323
 324 /****************************************************************************
 325  Send a message to a particular pid.
 326 ****************************************************************************/
 327
 328 static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
 329                                    struct server_id pid, int msg_type,
 330                                    const DATA_BLOB *data,
 331                                    struct messaging_backend *backend)
 332 {
 333         struct messaging_tdb_context *ctx = talloc_get_type(backend->private_data,
 334                                             struct messaging_tdb_context);
 335         struct messaging_array *msg_array;
 336         struct messaging_rec *rec;
 337         NTSTATUS status;
 338         TDB_DATA key;
 339         struct tdb_wrap *tdb = ctx->tdb;
 340         TALLOC_CTX *frame = talloc_stackframe();
 341
 342         /* NULL pointer means implicit length zero. */
 343         if (!data->data) {
 344                 SMB_ASSERT(data->length == 0);
 345         }
 346
 347         /*
 348          * Doing kill with a non-positive pid causes messages to be
 349          * sent to places we don't want.
 350          */
 351
 352         SMB_ASSERT(procid_to_pid(&pid) > 0);
 353
 354         key = message_key_pid(frame, pid);
 355
 356         if (tdb_chainlock(tdb->tdb, key) == -1) {
 357                 TALLOC_FREE(frame);
 358                 return NT_STATUS_LOCK_NOT_GRANTED;
 359         }
 360
 361         status = messaging_tdb_fetch(tdb->tdb, key, talloc_tos(), &msg_array);
 362
 363         if (!NT_STATUS_IS_OK(status)) {
 364                 goto done;
 365         }
 366
 367         if ((msg_type & MSG_FLAG_LOWPRIORITY)
 368             && (msg_array->num_messages > 1000)) {
 369                 DEBUG(5, ("Dropping message for PID %s\n",
 370                           procid_str_static(&pid)));
 371                 status = NT_STATUS_INSUFFICIENT_RESOURCES;
 372                 goto done;
 373         }
 374
 375         if (!(rec = TALLOC_REALLOC_ARRAY(talloc_tos(), msg_array->messages,
 376                                          struct messaging_rec,
 377                                          msg_array->num_messages+1))) {
 378                 status = NT_STATUS_NO_MEMORY;
 379                 goto done;
 380         }
 381
 382         rec[msg_array->num_messages].msg_version = MESSAGE_VERSION;
 383         rec[msg_array->num_messages].msg_type = msg_type & MSG_TYPE_MASK;
 384         rec[msg_array->num_messages].dest = pid;
 385         rec[msg_array->num_messages].src = procid_self();
 386         rec[msg_array->num_messages].buf = *data;
 387
 388         msg_array->messages = rec;
 389         msg_array->num_messages += 1;
 390
 391         status = messaging_tdb_store(tdb->tdb, key, msg_array);
 392
 393         if (!NT_STATUS_IS_OK(status)) {
 394                 goto done;
 395         }
 396
 397         status = message_notify(pid);
 398
 399         if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) {
 400                 DEBUG(2, ("pid %s doesn't exist - deleting messages record\n",
 401                           procid_str_static(&pid)));
 402                 tdb_delete(tdb->tdb, message_key_pid(talloc_tos(), pid));
 403         }
 404
 405  done:
 406         tdb_chainunlock(tdb->tdb, key);
 407         TALLOC_FREE(frame);
 408         return status;
 409 }
 410
 411 /****************************************************************************
 412  Retrieve all messages for the current process.
 413 ****************************************************************************/
 414
 415 static NTSTATUS retrieve_all_messages(TDB_CONTEXT *msg_tdb,
 416                                       TALLOC_CTX *mem_ctx,
 417                                       struct messaging_array **presult)
 418 {
 419         struct messaging_array *result;
 420         TDB_DATA key = message_key_pid(mem_ctx, procid_self());
 421         NTSTATUS status;
 422
 423         if (tdb_chainlock(msg_tdb, key) == -1) {
 424                 TALLOC_FREE(key.dptr);
 425                 return NT_STATUS_LOCK_NOT_GRANTED;
 426         }
 427
 428         status = messaging_tdb_fetch(msg_tdb, key, mem_ctx, &result);
 429
 430         /*
 431          * We delete the record here, tdb_set_max_dead keeps it around
 432          */
 433         tdb_delete(msg_tdb, key);
 434         tdb_chainunlock(msg_tdb, key);
 435
 436         if (NT_STATUS_IS_OK(status)) {
 437                 *presult = result;
 438         }
 439
 440         TALLOC_FREE(key.dptr);
 441
 442         return status;
 443 }
 444
 445 /****************************************************************************
 446  Receive and dispatch any messages pending for this process.
 447  JRA changed Dec 13 2006. Only one message handler now permitted per type.
 448  *NOTE*: Dispatch functions must be able to cope with incoming
 449  messages on an *odd* byte boundary.
 450 ****************************************************************************/
 451
 452 static void message_dispatch(struct messaging_context *msg_ctx)
 453 {
 454         struct messaging_tdb_context *ctx = talloc_get_type(msg_ctx->local->private_data,
 455                                             struct messaging_tdb_context);
 456         struct messaging_array *msg_array = NULL;
 457         struct tdb_wrap *tdb = ctx->tdb;
 458         NTSTATUS status;
 459         uint32 i;
 460
 461         if (ctx->received_messages == 0) {
 462                 return;
 463         }
 464
 465         DEBUG(10, ("message_dispatch: received_messages = %d\n",
 466                    ctx->received_messages));
 467
 468         status = retrieve_all_messages(tdb->tdb, NULL, &msg_array);
 469         if (!NT_STATUS_IS_OK(status)) {
 470                 DEBUG(0, ("message_dispatch: failed to retrieve messages: %s\n",
 471                            nt_errstr(status)));
 472                 return;
 473         }
 474
 475         ctx->received_messages = 0;
 476
 477         for (i=0; i<msg_array->num_messages; i++) {
 478                 messaging_dispatch_rec(msg_ctx, &msg_array->messages[i]);
 479         }
 480
 481         TALLOC_FREE(msg_array);
 482 }
 483
 484 /** @} **/