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 "system/filesys.h"
  47 #include "messages.h"
  48 #include "lib/util/tdb_wrap.h"
  49
  50 struct messaging_tdb_context {
  51         struct messaging_context *msg_ctx;
  52         struct tdb_wrap *tdb;
  53         struct tevent_signal *se;
  54         int received_messages;
  55 };
  56
  57 static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
  58                                    struct server_id pid, int msg_type,
  59                                    const DATA_BLOB *data,
  60                                    struct messaging_backend *backend);
  61 static void message_dispatch(struct messaging_context *msg_ctx);
  62
  63 static void messaging_tdb_signal_handler(struct tevent_context *ev_ctx,
  64                                          struct tevent_signal *se,
  65                                          int signum, int count,
  66                                          void *_info, void *private_data)
  67 {
  68         struct messaging_tdb_context *ctx = talloc_get_type(private_data,
  69                                             struct messaging_tdb_context);
  70
  71         ctx->received_messages++;
  72
  73         DEBUG(10, ("messaging_tdb_signal_handler: sig[%d] count[%d] msgs[%d]\n",
  74                    signum, count, ctx->received_messages));
  75
  76         message_dispatch(ctx->msg_ctx);
  77 }
  78
  79 /****************************************************************************
  80  Initialise the messaging functions.
  81 ****************************************************************************/
  82
  83 NTSTATUS messaging_tdb_init(struct messaging_context *msg_ctx,
  84                             TALLOC_CTX *mem_ctx,
  85                             struct messaging_backend **presult)
  86 {
  87         struct messaging_backend *result;
  88         struct messaging_tdb_context *ctx;
  89
  90         if (!(result = talloc(mem_ctx, struct messaging_backend))) {
  91                 DEBUG(0, ("talloc failed\n"));
  92                 return NT_STATUS_NO_MEMORY;
  93         }
  94
  95         ctx = talloc_zero(result, struct messaging_tdb_context);
  96         if (!ctx) {
  97                 DEBUG(0, ("talloc failed\n"));
  98                 TALLOC_FREE(result);
  99                 return NT_STATUS_NO_MEMORY;
 100         }
 101         result->private_data = ctx;
 102         result->send_fn = messaging_tdb_send;
 103
 104         ctx->msg_ctx = msg_ctx;
 105
 106         ctx->tdb = tdb_wrap_open(ctx, lock_path("messages.tdb"), 0,
 107                                  TDB_CLEAR_IF_FIRST|TDB_DEFAULT|TDB_VOLATILE|TDB_INCOMPATIBLE_HASH,
 108                                  O_RDWR|O_CREAT,0600);
 109
 110         if (!ctx->tdb) {
 111                 NTSTATUS status = map_nt_error_from_unix(errno);
 112                 DEBUG(2, ("ERROR: Failed to initialise messages database: "
 113                           "%s\n", strerror(errno)));
 114                 TALLOC_FREE(result);
 115                 return status;
 116         }
 117
 118         ctx->se = tevent_add_signal(msg_ctx->event_ctx,
 119                                     ctx,
 120                                     SIGUSR1, 0,
 121                                     messaging_tdb_signal_handler,
 122                                     ctx);
 123         if (!ctx->se) {
 124                 NTSTATUS status = map_nt_error_from_unix(errno);
 125                 DEBUG(0, ("ERROR: Failed to initialise messages signal handler: "
 126                           "%s\n", strerror(errno)));
 127                 TALLOC_FREE(result);
 128                 return status;
 129         }
 130
 131         sec_init();
 132
 133         *presult = result;
 134         return NT_STATUS_OK;
 135 }
 136
 137 bool messaging_tdb_parent_init(TALLOC_CTX *mem_ctx)
 138 {
 139         struct tdb_wrap *db;
 140
 141         /*
 142          * Open the tdb in the parent process (smbd) so that our
 143          * CLEAR_IF_FIRST optimization in tdb_reopen_all can properly
 144          * work.
 145          */
 146
 147         db = tdb_wrap_open(mem_ctx, lock_path("messages.tdb"), 0,
 148                            TDB_CLEAR_IF_FIRST|TDB_DEFAULT|TDB_VOLATILE|TDB_INCOMPATIBLE_HASH,
 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(mem_ctx, struct messaging_array))) {
 191                 return NT_STATUS_NO_MEMORY;
 192         }
 193
 194         data = tdb_fetch_compat(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, 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(&blob, mem_ctx, array,
 247                 (ndr_push_flags_fn_t)ndr_push_messaging_array);
 248
 249         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 250                 talloc_free(mem_ctx);
 251                 return ndr_map_error2ntstatus(ndr_err);
 252         }
 253
 254         if (DEBUGLEVEL >= 10) {
 255                 DEBUG(10, ("messaging_tdb_store:\n"));
 256                 NDR_PRINT_DEBUG(messaging_array, array);
 257         }
 258
 259         data.dptr = blob.data;
 260         data.dsize = blob.length;
 261
 262         ret = tdb_store(msg_tdb, key, data, TDB_REPLACE);
 263         TALLOC_FREE(mem_ctx);
 264
 265         return (ret == 0) ? NT_STATUS_OK : NT_STATUS_INTERNAL_DB_CORRUPTION;
 266 }
 267
 268 /****************************************************************************
 269  Notify a process that it has a message. If the process doesn't exist
 270  then delete its record in the database.
 271 ****************************************************************************/
 272
 273 static NTSTATUS message_notify(struct server_id procid)
 274 {
 275         pid_t pid = procid.pid;
 276         int ret;
 277         uid_t euid = geteuid();
 278
 279         /*
 280          * Doing kill with a non-positive pid causes messages to be
 281          * sent to places we don't want.
 282          */
 283
 284         SMB_ASSERT(pid > 0);
 285
 286         if (euid != 0) {
 287                 /* If we're not root become so to send the message. */
 288                 save_re_uid();
 289                 set_effective_uid(0);
 290         }
 291
 292         ret = kill(pid, SIGUSR1);
 293
 294         if (euid != 0) {
 295                 /* Go back to who we were. */
 296                 int saved_errno = errno;
 297                 restore_re_uid_fromroot();
 298                 errno = saved_errno;
 299         }
 300
 301         if (ret == 0) {
 302                 return NT_STATUS_OK;
 303         }
 304
 305         /*
 306          * Something has gone wrong
 307          */
 308
 309         DEBUG(2,("message to process %d failed - %s\n", (int)pid,
 310                  strerror(errno)));
 311
 312         /*
 313          * No call to map_nt_error_from_unix -- don't want to link in
 314          * errormap.o into lots of utils.
 315          */
 316
 317         if (errno == ESRCH)  return NT_STATUS_INVALID_HANDLE;
 318         if (errno == EINVAL) return NT_STATUS_INVALID_PARAMETER;
 319         if (errno == EPERM)  return NT_STATUS_ACCESS_DENIED;
 320         return NT_STATUS_UNSUCCESSFUL;
 321 }
 322
 323 /****************************************************************************
 324  Send a message to a particular pid.
 325 ****************************************************************************/
 326
 327 static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
 328                                    struct server_id pid, int msg_type,
 329                                    const DATA_BLOB *data,
 330                                    struct messaging_backend *backend)
 331 {
 332         struct messaging_tdb_context *ctx = talloc_get_type(backend->private_data,
 333                                             struct messaging_tdb_context);
 334         struct messaging_array *msg_array;
 335         struct messaging_rec *rec;
 336         NTSTATUS status;
 337         TDB_DATA key;
 338         struct tdb_wrap *tdb = ctx->tdb;
 339         TALLOC_CTX *frame = talloc_stackframe();
 340
 341         /* NULL pointer means implicit length zero. */
 342         if (!data->data) {
 343                 SMB_ASSERT(data->length == 0);
 344         }
 345
 346         /*
 347          * Doing kill with a non-positive pid causes messages to be
 348          * sent to places we don't want.
 349          */
 350
 351         SMB_ASSERT(procid_to_pid(&pid) > 0);
 352
 353         key = message_key_pid(frame, pid);
 354
 355         if (tdb_chainlock(tdb->tdb, key) != 0) {
 356                 TALLOC_FREE(frame);
 357                 return NT_STATUS_LOCK_NOT_GRANTED;
 358         }
 359
 360         status = messaging_tdb_fetch(tdb->tdb, key, talloc_tos(), &msg_array);
 361
 362         if (!NT_STATUS_IS_OK(status)) {
 363                 goto done;
 364         }
 365
 366         if ((msg_type & MSG_FLAG_LOWPRIORITY)
 367             && (msg_array->num_messages > 1000)) {
 368                 DEBUG(5, ("Dropping message for PID %s\n",
 369                           procid_str_static(&pid)));
 370                 status = NT_STATUS_INSUFFICIENT_RESOURCES;
 371                 goto done;
 372         }
 373
 374         if (!(rec = talloc_realloc(talloc_tos(), msg_array->messages,
 375                                          struct messaging_rec,
 376                                          msg_array->num_messages+1))) {
 377                 status = NT_STATUS_NO_MEMORY;
 378                 goto done;
 379         }
 380
 381         rec[msg_array->num_messages].msg_version = MESSAGE_VERSION;
 382         rec[msg_array->num_messages].msg_type = msg_type & MSG_TYPE_MASK;
 383         rec[msg_array->num_messages].dest = pid;
 384         rec[msg_array->num_messages].src = msg_ctx->id;
 385         rec[msg_array->num_messages].buf = *data;
 386
 387         msg_array->messages = rec;
 388         msg_array->num_messages += 1;
 389
 390         status = messaging_tdb_store(tdb->tdb, key, msg_array);
 391
 392         if (!NT_STATUS_IS_OK(status)) {
 393                 goto done;
 394         }
 395
 396         status = message_notify(pid);
 397
 398         if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) {
 399                 DEBUG(2, ("pid %s doesn't exist - deleting messages record\n",
 400                           procid_str_static(&pid)));
 401                 tdb_delete(tdb->tdb, message_key_pid(talloc_tos(), pid));
 402         }
 403
 404  done:
 405         tdb_chainunlock(tdb->tdb, key);
 406         TALLOC_FREE(frame);
 407         return status;
 408 }
 409
 410 /****************************************************************************
 411  Retrieve all messages for a process.
 412 ****************************************************************************/
 413
 414 static NTSTATUS retrieve_all_messages(TDB_CONTEXT *msg_tdb,
 415                                       struct server_id id,
 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, id);
 421         NTSTATUS status;
 422
 423         if (tdb_chainlock(msg_tdb, key) != 0) {
 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, msg_ctx->id, 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 /** @} **/