source/smbd/notify_internal.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Copyright (C) Andrew Tridgell 2006
   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   this is the change notify database. It implements mechanisms for
  22   storing current change notify waiters in a tdb, and checking if a
  23   given event matches any of the stored notify waiiters.
  24 */
  25
  26 #include "includes.h"
  27 #include "librpc/gen_ndr/ndr_notify.h"
  28
  29 struct notify_context {
  30         struct db_context *db;
  31         struct server_id server;
  32         struct messaging_context *messaging_ctx;
  33         struct notify_list *list;
  34         struct notify_array *array;
  35         int seqnum;
  36         struct sys_notify_context *sys_notify_ctx;
  37         TDB_DATA key;
  38 };
  39
  40
  41 struct notify_list {
  42         struct notify_list *next, *prev;
  43         void *private_data;
  44         void (*callback)(void *, const struct notify_event *);
  45         void *sys_notify_handle;
  46         int depth;
  47 };
  48
  49 #define NOTIFY_KEY "notify array"
  50
  51 #define NOTIFY_ENABLE           "notify:enable"
  52 #define NOTIFY_ENABLE_DEFAULT   True
  53
  54 static NTSTATUS notify_remove_all(struct notify_context *notify,
  55                                   const struct server_id *server);
  56 static void notify_handler(struct messaging_context *msg_ctx, void *private_data,
  57                            uint32_t msg_type, struct server_id server_id, DATA_BLOB *data);
  58
  59 /*
  60   destroy the notify context
  61 */
  62 static int notify_destructor(struct notify_context *notify)
  63 {
  64         messaging_deregister(notify->messaging_ctx, MSG_PVFS_NOTIFY, notify);
  65
  66         if (notify->list != NULL) {
  67                 notify_remove_all(notify, &notify->server);
  68         }
  69
  70         return 0;
  71 }
  72
  73 /*
  74   Open up the notify.tdb database. You should close it down using
  75   talloc_free(). We need the messaging_ctx to allow for notifications
  76   via internal messages
  77 */
  78 struct notify_context *notify_init(TALLOC_CTX *mem_ctx, struct server_id server,
  79                                    struct messaging_context *messaging_ctx,
  80                                    struct event_context *ev,
  81                                    connection_struct *conn)
  82 {
  83         struct notify_context *notify;
  84
  85         if (!lp_change_notify(conn->params)) {
  86                 return NULL;
  87         }
  88
  89         notify = talloc(mem_ctx, struct notify_context);
  90         if (notify == NULL) {
  91                 return NULL;
  92         }
  93
  94         notify->db = db_open(notify, lock_path("notify.tdb"),
  95                                   0, TDB_SEQNUM|TDB_CLEAR_IF_FIRST,
  96                                   O_RDWR|O_CREAT, 0644);
  97         if (notify->db == NULL) {
  98                 talloc_free(notify);
  99                 return NULL;
 100         }
 101
 102         notify->server = server;
 103         notify->messaging_ctx = messaging_ctx;
 104         notify->list = NULL;
 105         notify->array = NULL;
 106         notify->seqnum = notify->db->get_seqnum(notify->db);
 107         notify->key = string_term_tdb_data(NOTIFY_KEY);
 108
 109         talloc_set_destructor(notify, notify_destructor);
 110
 111         /* register with the messaging subsystem for the notify
 112            message type */
 113         messaging_register(notify->messaging_ctx, notify,
 114                            MSG_PVFS_NOTIFY, notify_handler);
 115
 116         notify->sys_notify_ctx = sys_notify_context_create(conn, notify, ev);
 117
 118         return notify;
 119 }
 120
 121 /*
 122   lock and fetch the record
 123 */
 124 static NTSTATUS notify_fetch_locked(struct notify_context *notify, struct db_record **rec)
 125 {
 126         *rec = notify->db->fetch_locked(notify->db, notify, notify->key);
 127         if (*rec == NULL) {
 128                 return NT_STATUS_INTERNAL_DB_CORRUPTION;
 129         }
 130         return NT_STATUS_OK;
 131 }
 132
 133 /*
 134   load the notify array
 135 */
 136 static NTSTATUS notify_load(struct notify_context *notify, struct db_record *rec)
 137 {
 138         TDB_DATA dbuf;
 139         DATA_BLOB blob;
 140         NTSTATUS status;
 141         int seqnum;
 142
 143         seqnum = notify->db->get_seqnum(notify->db);
 144
 145         if (seqnum == notify->seqnum && notify->array != NULL) {
 146                 return NT_STATUS_OK;
 147         }
 148
 149         notify->seqnum = seqnum;
 150
 151         talloc_free(notify->array);
 152         notify->array = TALLOC_ZERO_P(notify, struct notify_array);
 153         NT_STATUS_HAVE_NO_MEMORY(notify->array);
 154
 155         if (!rec) {
 156                 if (notify->db->fetch(notify->db, notify, notify->key, &dbuf) != 0) {
 157                         return NT_STATUS_INTERNAL_DB_CORRUPTION;
 158                 }
 159         } else {
 160                 dbuf = rec->value;
 161         }
 162
 163         blob.data = (uint8 *)dbuf.dptr;
 164         blob.length = dbuf.dsize;
 165
 166         if (blob.length == 0) {
 167                 status = NT_STATUS_OK;
 168         } else {
 169                 status = ndr_pull_struct_blob(&blob, notify->array, notify->array,
 170                                               (ndr_pull_flags_fn_t)ndr_pull_notify_array);
 171         }
 172
 173         if (DEBUGLEVEL >= 10) {
 174                 DEBUG(10, ("notify_load:\n"));
 175                 NDR_PRINT_DEBUG(notify_array, notify->array);
 176         }
 177
 178         if (!rec) {
 179                 talloc_free(dbuf.dptr);
 180         }
 181
 182         return status;
 183 }
 184
 185 /*
 186   compare notify entries for sorting
 187 */
 188 static int notify_compare(const void *p1, const void *p2)
 189 {
 190         const struct notify_entry *e1 = (const struct notify_entry *)p1;
 191         const struct notify_entry *e2 = (const struct notify_entry *)p2;
 192         return strcmp(e1->path, e2->path);
 193 }
 194
 195 /*
 196   save the notify array
 197 */
 198 static NTSTATUS notify_save(struct notify_context *notify, struct db_record *rec)
 199 {
 200         TDB_DATA dbuf;
 201         DATA_BLOB blob;
 202         NTSTATUS status;
 203         TALLOC_CTX *tmp_ctx;
 204
 205         /* if possible, remove some depth arrays */
 206         while (notify->array->num_depths > 0 &&
 207                notify->array->depth[notify->array->num_depths-1].num_entries == 0) {
 208                 notify->array->num_depths--;
 209         }
 210
 211         /* we might just be able to delete the record */
 212         if (notify->array->num_depths == 0) {
 213                 return rec->delete_rec(rec);
 214         }
 215
 216         tmp_ctx = talloc_new(notify);
 217         NT_STATUS_HAVE_NO_MEMORY(tmp_ctx);
 218
 219         status = ndr_push_struct_blob(&blob, tmp_ctx, notify->array,
 220                                       (ndr_push_flags_fn_t)ndr_push_notify_array);
 221         if (!NT_STATUS_IS_OK(status)) {
 222                 talloc_free(tmp_ctx);
 223                 return status;
 224         }
 225
 226         if (DEBUGLEVEL >= 10) {
 227                 DEBUG(10, ("notify_save:\n"));
 228                 NDR_PRINT_DEBUG(notify_array, notify->array);
 229         }
 230
 231         dbuf.dptr = blob.data;
 232         dbuf.dsize = blob.length;
 233
 234         status = rec->store(rec, dbuf, TDB_REPLACE);
 235         talloc_free(tmp_ctx);
 236
 237         return status;
 238 }
 239
 240
 241 /*
 242   handle incoming notify messages
 243 */
 244 static void notify_handler(struct messaging_context *msg_ctx, void *private_data,
 245                            uint32_t msg_type, struct server_id server_id, DATA_BLOB *data)
 246 {
 247         struct notify_context *notify = talloc_get_type(private_data, struct notify_context);
 248         NTSTATUS status;
 249         struct notify_event ev;
 250         TALLOC_CTX *tmp_ctx = talloc_new(notify);
 251         struct notify_list *listel;
 252
 253         if (tmp_ctx == NULL) {
 254                 return;
 255         }
 256
 257         status = ndr_pull_struct_blob(data, tmp_ctx, &ev,
 258                                       (ndr_pull_flags_fn_t)ndr_pull_notify_event);
 259         if (!NT_STATUS_IS_OK(status)) {
 260                 talloc_free(tmp_ctx);
 261                 return;
 262         }
 263
 264         for (listel=notify->list;listel;listel=listel->next) {
 265                 if (listel->private_data == ev.private_data) {
 266                         listel->callback(listel->private_data, &ev);
 267                         break;
 268                 }
 269         }
 270
 271         talloc_free(tmp_ctx);
 272 }
 273
 274 /*
 275   callback from sys_notify telling us about changes from the OS
 276 */
 277 static void sys_notify_callback(struct sys_notify_context *ctx,
 278                                 void *ptr, struct notify_event *ev)
 279 {
 280         struct notify_list *listel = talloc_get_type(ptr, struct notify_list);
 281         ev->private_data = listel;
 282         DEBUG(10, ("sys_notify_callback called with action=%d, for %s\n",
 283                    ev->action, ev->path));
 284         listel->callback(listel->private_data, ev);
 285 }
 286
 287 /*
 288   add an entry to the notify array
 289 */
 290 static NTSTATUS notify_add_array(struct notify_context *notify, struct db_record *rec,
 291                                  struct notify_entry *e,
 292                                  void *private_data, int depth)
 293 {
 294         int i;
 295         struct notify_depth *d;
 296         struct notify_entry *ee;
 297
 298         /* possibly expand the depths array */
 299         if (depth >= notify->array->num_depths) {
 300                 d = talloc_realloc(notify->array, notify->array->depth,
 301                                    struct notify_depth, depth+1);
 302                 NT_STATUS_HAVE_NO_MEMORY(d);
 303                 for (i=notify->array->num_depths;i<=depth;i++) {
 304                         ZERO_STRUCT(d[i]);
 305                 }
 306                 notify->array->depth = d;
 307                 notify->array->num_depths = depth+1;
 308         }
 309         d = &notify->array->depth[depth];
 310
 311         /* expand the entries array */
 312         ee = talloc_realloc(notify->array->depth, d->entries, struct notify_entry,
 313                             d->num_entries+1);
 314         NT_STATUS_HAVE_NO_MEMORY(ee);
 315         d->entries = ee;
 316
 317         d->entries[d->num_entries] = *e;
 318         d->entries[d->num_entries].private_data = private_data;
 319         d->entries[d->num_entries].server = notify->server;
 320         d->entries[d->num_entries].path_len = strlen(e->path);
 321         d->num_entries++;
 322
 323         d->max_mask |= e->filter;
 324         d->max_mask_subdir |= e->subdir_filter;
 325
 326         if (d->num_entries > 1) {
 327                 qsort(d->entries, d->num_entries, sizeof(d->entries[0]), notify_compare);
 328         }
 329
 330         /* recalculate the maximum masks */
 331         d->max_mask = 0;
 332         d->max_mask_subdir = 0;
 333
 334         for (i=0;i<d->num_entries;i++) {
 335                 d->max_mask |= d->entries[i].filter;
 336                 d->max_mask_subdir |= d->entries[i].subdir_filter;
 337         }
 338
 339         return notify_save(notify, rec);
 340 }
 341
 342 /*
 343   add a notify watch. This is called when a notify is first setup on a open
 344   directory handle.
 345 */
 346 NTSTATUS notify_add(struct notify_context *notify, struct notify_entry *e0,
 347                     void (*callback)(void *, const struct notify_event *),
 348                     void *private_data)
 349 {
 350         struct notify_entry e = *e0;
 351         NTSTATUS status;
 352         char *tmp_path = NULL;
 353         struct notify_list *listel;
 354         size_t len;
 355         int depth;
 356         struct db_record *rec;
 357
 358         /* see if change notify is enabled at all */
 359         if (notify == NULL) {
 360                 return NT_STATUS_NOT_IMPLEMENTED;
 361         }
 362
 363         status = notify_fetch_locked(notify, &rec);
 364         NT_STATUS_NOT_OK_RETURN(status);
 365
 366         status = notify_load(notify, rec);
 367         if (!NT_STATUS_IS_OK(status)) {
 368                 talloc_free(rec);
 369                 return status;
 370         }
 371
 372         /* cope with /. on the end of the path */
 373         len = strlen(e.path);
 374         if (len > 1 && e.path[len-1] == '.' && e.path[len-2] == '/') {
 375                 tmp_path = talloc_strndup(notify, e.path, len-2);
 376                 if (tmp_path == NULL) {
 377                         status = NT_STATUS_NO_MEMORY;
 378                         goto done;
 379                 }
 380                 e.path = tmp_path;
 381         }
 382
 383         depth = count_chars(e.path, '/');
 384
 385         listel = TALLOC_ZERO_P(notify, struct notify_list);
 386         if (listel == NULL) {
 387                 status = NT_STATUS_NO_MEMORY;
 388                 goto done;
 389         }
 390
 391         listel->private_data = private_data;
 392         listel->callback = callback;
 393         listel->depth = depth;
 394         DLIST_ADD(notify->list, listel);
 395
 396         /* ignore failures from sys_notify */
 397         if (notify->sys_notify_ctx != NULL) {
 398                 /*
 399                   this call will modify e.filter and e.subdir_filter
 400                   to remove bits handled by the backend
 401                 */
 402                 status = sys_notify_watch(notify->sys_notify_ctx, &e,
 403                                           sys_notify_callback, listel,
 404                                           &listel->sys_notify_handle);
 405                 if (NT_STATUS_IS_OK(status)) {
 406                         talloc_steal(listel, listel->sys_notify_handle);
 407                 }
 408         }
 409
 410         /* if the system notify handler couldn't handle some of the
 411            filter bits, or couldn't handle a request for recursion
 412            then we need to install it in the array used for the
 413            intra-samba notify handling */
 414         if (e.filter != 0 || e.subdir_filter != 0) {
 415                 status = notify_add_array(notify, rec, &e, private_data, depth);
 416         }
 417
 418 done:
 419         talloc_free(rec);
 420         talloc_free(tmp_path);
 421
 422         return status;
 423 }
 424
 425 /*
 426   remove a notify watch. Called when the directory handle is closed
 427 */
 428 NTSTATUS notify_remove(struct notify_context *notify, void *private_data)
 429 {
 430         NTSTATUS status;
 431         struct notify_list *listel;
 432         int i, depth;
 433         struct notify_depth *d;
 434         struct db_record *rec;
 435
 436         /* see if change notify is enabled at all */
 437         if (notify == NULL) {
 438                 return NT_STATUS_NOT_IMPLEMENTED;
 439         }
 440
 441         for (listel=notify->list;listel;listel=listel->next) {
 442                 if (listel->private_data == private_data) {
 443                         DLIST_REMOVE(notify->list, listel);
 444                         break;
 445                 }
 446         }
 447         if (listel == NULL) {
 448                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 449         }
 450
 451         depth = listel->depth;
 452
 453         talloc_free(listel);
 454
 455         status = notify_fetch_locked(notify, &rec);
 456         NT_STATUS_NOT_OK_RETURN(status);
 457
 458         status = notify_load(notify, rec);
 459         if (!NT_STATUS_IS_OK(status)) {
 460                 talloc_free(rec);
 461                 return status;
 462         }
 463
 464         if (depth >= notify->array->num_depths) {
 465                 talloc_free(rec);
 466                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 467         }
 468
 469         /* we only have to search at the depth of this element */
 470         d = &notify->array->depth[depth];
 471
 472         for (i=0;i<d->num_entries;i++) {
 473                 if (private_data == d->entries[i].private_data &&
 474                     cluster_id_equal(&notify->server, &d->entries[i].server)) {
 475                         break;
 476                 }
 477         }
 478         if (i == d->num_entries) {
 479                 talloc_free(rec);
 480                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 481         }
 482
 483         if (i < d->num_entries-1) {
 484                 memmove(&d->entries[i], &d->entries[i+1],
 485                         sizeof(d->entries[i])*(d->num_entries-(i+1)));
 486         }
 487         d->num_entries--;
 488
 489         status = notify_save(notify, rec);
 490
 491         talloc_free(rec);
 492
 493         return status;
 494 }
 495
 496 /*
 497   remove all notify watches for a messaging server
 498 */
 499 static NTSTATUS notify_remove_all(struct notify_context *notify,
 500                                   const struct server_id *server)
 501 {
 502         NTSTATUS status;
 503         int i, depth, del_count=0;
 504         struct db_record *rec;
 505
 506         status = notify_fetch_locked(notify, &rec);
 507         NT_STATUS_NOT_OK_RETURN(status);
 508
 509         status = notify_load(notify, rec);
 510         if (!NT_STATUS_IS_OK(status)) {
 511                 talloc_free(rec);
 512                 return status;
 513         }
 514
 515         /* we have to search for all entries across all depths, looking for matches
 516            for the server id */
 517         for (depth=0;depth<notify->array->num_depths;depth++) {
 518                 struct notify_depth *d = &notify->array->depth[depth];
 519                 for (i=0;i<d->num_entries;i++) {
 520                         if (cluster_id_equal(server, &d->entries[i].server)) {
 521                                 if (i < d->num_entries-1) {
 522                                         memmove(&d->entries[i], &d->entries[i+1],
 523                                                 sizeof(d->entries[i])*(d->num_entries-(i+1)));
 524                                 }
 525                                 i--;
 526                                 d->num_entries--;
 527                                 del_count++;
 528                         }
 529                 }
 530         }
 531
 532         if (del_count > 0) {
 533                 status = notify_save(notify, rec);
 534         }
 535
 536         talloc_free(rec);
 537
 538         return status;
 539 }
 540
 541
 542 /*
 543   send a notify message to another messaging server
 544 */
 545 static NTSTATUS notify_send(struct notify_context *notify, struct notify_entry *e,
 546                             const char *path, uint32_t action)
 547 {
 548         struct notify_event ev;
 549         DATA_BLOB data;
 550         NTSTATUS status;
 551         TALLOC_CTX *tmp_ctx;
 552
 553         ev.action = action;
 554         ev.path = path;
 555         ev.private_data = e->private_data;
 556
 557         tmp_ctx = talloc_new(notify);
 558
 559         status = ndr_push_struct_blob(&data, tmp_ctx, &ev,
 560                                       (ndr_push_flags_fn_t)ndr_push_notify_event);
 561         if (!NT_STATUS_IS_OK(status)) {
 562                 talloc_free(tmp_ctx);
 563                 return status;
 564         }
 565
 566         status = messaging_send(notify->messaging_ctx, e->server,
 567                                 MSG_PVFS_NOTIFY, &data);
 568         talloc_free(tmp_ctx);
 569         return status;
 570 }
 571
 572
 573 /*
 574   trigger a notify message for anyone waiting on a matching event
 575
 576   This function is called a lot, and needs to be very fast. The unusual data structure
 577   and traversal is designed to be fast in the average case, even for large numbers of
 578   notifies
 579 */
 580 void notify_trigger(struct notify_context *notify,
 581                     uint32_t action, uint32_t filter, const char *path)
 582 {
 583         NTSTATUS status;
 584         int depth;
 585         const char *p, *next_p;
 586
 587         DEBUG(10, ("notify_trigger called action=0x%x, filter=0x%x, "
 588                    "path=%s\n", (unsigned)action, (unsigned)filter, path));
 589
 590         /* see if change notify is enabled at all */
 591         if (notify == NULL) {
 592                 return;
 593         }
 594
 595  again:
 596         status = notify_load(notify, NULL);
 597         if (!NT_STATUS_IS_OK(status)) {
 598                 return;
 599         }
 600
 601         /* loop along the given path, working with each directory depth separately */
 602         for (depth=0,p=path;
 603              p && depth < notify->array->num_depths;
 604              p=next_p,depth++) {
 605                 int p_len = p - path;
 606                 int min_i, max_i, i;
 607                 struct notify_depth *d = &notify->array->depth[depth];
 608                 next_p = strchr(p+1, '/');
 609
 610                 /* see if there are any entries at this depth */
 611                 if (d->num_entries == 0) continue;
 612
 613                 /* try to skip based on the maximum mask. If next_p is
 614                  NULL then we know it will be a 'this directory'
 615                  match, otherwise it must be a subdir match */
 616                 if (next_p != NULL) {
 617                         if (0 == (filter & d->max_mask_subdir)) {
 618                                 continue;
 619                         }
 620                 } else {
 621                         if (0 == (filter & d->max_mask)) {
 622                                 continue;
 623                         }
 624                 }
 625
 626                 /* we know there is an entry here worth looking
 627                  for. Use a bisection search to find the first entry
 628                  with a matching path */
 629                 min_i = 0;
 630                 max_i = d->num_entries-1;
 631
 632                 while (min_i < max_i) {
 633                         struct notify_entry *e;
 634                         int cmp;
 635                         i = (min_i+max_i)/2;
 636                         e = &d->entries[i];
 637                         cmp = strncmp(path, e->path, p_len);
 638                         if (cmp == 0) {
 639                                 if (p_len == e->path_len) {
 640                                         max_i = i;
 641                                 } else {
 642                                         max_i = i-1;
 643                                 }
 644                         } else if (cmp < 0) {
 645                                 max_i = i-1;
 646                         } else {
 647                                 min_i = i+1;
 648                         }
 649                 }
 650
 651                 if (min_i != max_i) {
 652                         /* none match */
 653                         continue;
 654                 }
 655
 656                 /* we now know that the entries start at min_i */
 657                 for (i=min_i;i<d->num_entries;i++) {
 658                         struct notify_entry *e = &d->entries[i];
 659                         if (p_len != e->path_len ||
 660                             strncmp(path, e->path, p_len) != 0) break;
 661                         if (next_p != NULL) {
 662                                 if (0 == (filter & e->subdir_filter)) {
 663                                         continue;
 664                                 }
 665                         } else {
 666                                 if (0 == (filter & e->filter)) {
 667                                         continue;
 668                                 }
 669                         }
 670                         status = notify_send(notify, e, path + e->path_len + 1,
 671                                              action);
 672
 673                         if (NT_STATUS_EQUAL(
 674                                     status, NT_STATUS_INVALID_HANDLE)) {
 675                                 struct server_id server = e->server;
 676
 677                                 DEBUG(10, ("Deleting notify entries for "
 678                                            "process %s because it's gone\n",
 679                                            procid_str_static(&e->server)));
 680                                 notify_remove_all(notify, &server);
 681                                 goto again;
 682                         }
 683                 }
 684         }
 685 }