source3/lib/server_prefork.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Common server globals
   4
   5    Copyright (C) Simo Sorce <idra@samba.org> 2011
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "includes.h"
  22 #include "serverid.h"
  23 #include "messages.h"
  24 #include "system/time.h"
  25 #include "system/shmem.h"
  26 #include "system/filesys.h"
  27 #include "server_prefork.h"
  28 #include "../lib/util/samba_util.h"
  29 #include "../lib/util/tevent_unix.h"
  30
  31 struct prefork_pool {
  32
  33         int listen_fd_size;
  34         int *listen_fds;
  35
  36         prefork_main_fn_t *main_fn;
  37         void *private_data;
  38
  39         int pool_size;
  40         struct pf_worker_data *pool;
  41
  42         int allowed_clients;
  43
  44         prefork_sigchld_fn_t *sigchld_fn;
  45         void *sigchld_data;
  46 };
  47
  48 static bool prefork_setup_sigchld_handler(struct tevent_context *ev_ctx,
  49                                             struct prefork_pool *pfp);
  50
  51 static int prefork_pool_destructor(struct prefork_pool *pfp)
  52 {
  53         anonymous_shared_free(pfp->pool);
  54         return 0;
  55 }
  56
  57 bool prefork_create_pool(TALLOC_CTX *mem_ctx,
  58                          struct tevent_context *ev_ctx,
  59                          struct messaging_context *msg_ctx,
  60                          int listen_fd_size, int *listen_fds,
  61                          int min_children, int max_children,
  62                          prefork_main_fn_t *main_fn, void *private_data,
  63                          struct prefork_pool **pf_pool)
  64 {
  65         struct prefork_pool *pfp;
  66         pid_t pid;
  67         time_t now = time(NULL);
  68         size_t data_size;
  69         int ret;
  70         int i;
  71         bool ok;
  72
  73         pfp = talloc_zero(mem_ctx, struct prefork_pool);
  74         if (!pfp) {
  75                 DEBUG(1, ("Out of memory!\n"));
  76                 return false;
  77         }
  78         pfp->listen_fd_size = listen_fd_size;
  79         pfp->listen_fds = talloc_array(pfp, int, listen_fd_size);
  80         if (!pfp->listen_fds) {
  81                 DEBUG(1, ("Out of memory!\n"));
  82                 return false;
  83         }
  84         for (i = 0; i < listen_fd_size; i++) {
  85                 pfp->listen_fds[i] = listen_fds[i];
  86                 /* force sockets in non-blocking mode */
  87                 set_blocking(listen_fds[i], false);
  88         }
  89         pfp->main_fn = main_fn;
  90         pfp->private_data = private_data;
  91
  92         pfp->pool_size = max_children;
  93         data_size = sizeof(struct pf_worker_data) * max_children;
  94
  95         pfp->pool = (struct pf_worker_data *)anonymous_shared_allocate(
  96                 data_size);
  97         if (pfp->pool == NULL) {
  98                 DEBUG(1, ("Failed to mmap memory for prefork pool!\n"));
  99                 talloc_free(pfp);
 100                 return false;
 101         }
 102         talloc_set_destructor(pfp, prefork_pool_destructor);
 103
 104         for (i = 0; i < min_children; i++) {
 105
 106                 pfp->pool[i].allowed_clients = 1;
 107                 pfp->pool[i].started = now;
 108
 109                 pid = fork();
 110                 switch (pid) {
 111                 case -1:
 112                         DEBUG(1, ("Failed to prefork child n. %d !\n", i));
 113                         break;
 114
 115                 case 0: /* THE CHILD */
 116
 117                         pfp->pool[i].status = PF_WORKER_ALIVE;
 118                         ret = pfp->main_fn(ev_ctx, msg_ctx,
 119                                            &pfp->pool[i], i + 1,
 120                                            pfp->listen_fd_size,
 121                                            pfp->listen_fds,
 122                                            pfp->private_data);
 123                         exit(ret);
 124
 125                 default: /* THE PARENT */
 126                         pfp->pool[i].pid = pid;
 127                         break;
 128                 }
 129         }
 130
 131         ok = prefork_setup_sigchld_handler(ev_ctx, pfp);
 132         if (!ok) {
 133                 DEBUG(1, ("Failed to setup SIGCHLD Handler!\n"));
 134                 talloc_free(pfp);
 135                 return false;
 136         }
 137
 138         *pf_pool = pfp;
 139         return true;
 140 }
 141
 142 /* Provide the new max children number in new_max
 143  * (must be larger than current max).
 144  * Returns: 0 if all fine
 145  *          ENOSPC if mremap fails to expand
 146  *          EINVAL if new_max is invalid
 147  */
 148 int prefork_expand_pool(struct prefork_pool *pfp, int new_max)
 149 {
 150         struct prefork_pool *pool;
 151         size_t old_size;
 152         size_t new_size;
 153         int ret;
 154
 155         if (new_max <= pfp->pool_size) {
 156                 return EINVAL;
 157         }
 158
 159         old_size = sizeof(struct pf_worker_data) * pfp->pool_size;
 160         new_size = sizeof(struct pf_worker_data) * new_max;
 161
 162         pool = (struct prefork_pool *)anonymous_shared_resize(
 163                 &pfp->pool, new_size, false);
 164         if (pool == NULL) {
 165                 ret = errno;
 166                 DEBUG(3, ("Failed to mremap memory (%d: %s)!\n",
 167                           ret, strerror(ret)));
 168                 return ret;
 169         }
 170
 171         memset(&pool[pfp->pool_size], 0, new_size - old_size);
 172
 173         pfp->pool_size = new_max;
 174
 175         return 0;
 176 }
 177
 178 int prefork_add_children(struct tevent_context *ev_ctx,
 179                          struct messaging_context *msg_ctx,
 180                          struct prefork_pool *pfp,
 181                          int num_children)
 182 {
 183         pid_t pid;
 184         time_t now = time(NULL);
 185         int ret;
 186         int i, j;
 187
 188         for (i = 0, j = 0; i < pfp->pool_size && j < num_children; i++) {
 189
 190                 if (pfp->pool[i].status != PF_WORKER_NONE) {
 191                         continue;
 192                 }
 193
 194                 pfp->pool[i].allowed_clients = 1;
 195                 pfp->pool[i].started = now;
 196
 197                 pid = fork();
 198                 switch (pid) {
 199                 case -1:
 200                         DEBUG(1, ("Failed to prefork child n. %d !\n", j));
 201                         break;
 202
 203                 case 0: /* THE CHILD */
 204
 205                         pfp->pool[i].status = PF_WORKER_ALIVE;
 206                         ret = pfp->main_fn(ev_ctx, msg_ctx,
 207                                            &pfp->pool[i], i + 1,
 208                                            pfp->listen_fd_size,
 209                                            pfp->listen_fds,
 210                                            pfp->private_data);
 211
 212                         pfp->pool[i].status = PF_WORKER_EXITING;
 213                         exit(ret);
 214
 215                 default: /* THE PARENT */
 216                         pfp->pool[i].pid = pid;
 217                         j++;
 218                         break;
 219                 }
 220         }
 221
 222         DEBUG(5, ("Added %d children!\n", j));
 223
 224         return j;
 225 }
 226
 227 struct prefork_oldest {
 228         int num;
 229         time_t started;
 230 };
 231
 232 /* sort in inverse order */
 233 static int prefork_sort_oldest(const void *ap, const void *bp)
 234 {
 235         const struct prefork_oldest *a = (const struct prefork_oldest *)ap;
 236         const struct prefork_oldest *b = (const struct prefork_oldest *)bp;
 237
 238         if (a->started == b->started) {
 239                 return 0;
 240         }
 241         if (a->started < b->started) {
 242                 return 1;
 243         }
 244         return -1;
 245 }
 246
 247 int prefork_retire_children(struct messaging_context *msg_ctx,
 248                             struct prefork_pool *pfp,
 249                             int num_children, time_t age_limit)
 250 {
 251         const DATA_BLOB ping = data_blob_null;
 252         time_t now = time(NULL);
 253         struct prefork_oldest *oldest;
 254         int i, j;
 255
 256         oldest = talloc_array(pfp, struct prefork_oldest, pfp->pool_size);
 257         if (!oldest) {
 258                 return -1;
 259         }
 260
 261         for (i = 0; i < pfp->pool_size; i++) {
 262                 oldest[i].num = i;
 263                 if (pfp->pool[i].status == PF_WORKER_ALIVE ||
 264                     pfp->pool[i].status == PF_WORKER_ACCEPTING) {
 265                         oldest[i].started = pfp->pool[i].started;
 266                 } else {
 267                         oldest[i].started = now;
 268                 }
 269         }
 270
 271         qsort(oldest, pfp->pool_size,
 272                 sizeof(struct prefork_oldest),
 273                 prefork_sort_oldest);
 274
 275         for (i = 0, j = 0; i < pfp->pool_size && j < num_children; i++) {
 276                 if (((pfp->pool[i].status == PF_WORKER_ALIVE) &&
 277                      (pfp->pool[i].num_clients < 1)) &&
 278                     (pfp->pool[i].started <= age_limit)) {
 279                         /* tell the child it's time to give up */
 280                         DEBUG(5, ("Retiring pid %u!\n", (unsigned int)pfp->pool[i].pid));
 281                         pfp->pool[i].cmds = PF_SRV_MSG_EXIT;
 282                         messaging_send(msg_ctx,
 283                                         pid_to_procid(pfp->pool[i].pid),
 284                                         MSG_PREFORK_PARENT_EVENT, &ping);
 285                         j++;
 286                 }
 287         }
 288
 289         return j;
 290 }
 291
 292 int prefork_count_children(struct prefork_pool *pfp, int *active)
 293 {
 294         int i, a, t;
 295
 296         a = 0;
 297         t = 0;
 298         for (i = 0; i < pfp->pool_size; i++) {
 299                 if (pfp->pool[i].status == PF_WORKER_NONE) {
 300                         continue;
 301                 }
 302
 303                 t++;
 304
 305                 if ((pfp->pool[i].status == PF_WORKER_EXITING) ||
 306                     (pfp->pool[i].num_clients <= 0)) {
 307                         continue;
 308                 }
 309
 310                 a++;
 311         }
 312
 313         if (active) {
 314                 *active = a;
 315         }
 316         return t;
 317 }
 318
 319 static void prefork_cleanup_loop(struct prefork_pool *pfp)
 320 {
 321         int status;
 322         pid_t pid;
 323         int i;
 324
 325         /* TODO: should we use a process group id wait instead of looping ? */
 326         for (i = 0; i < pfp->pool_size; i++) {
 327                 if (pfp->pool[i].status == PF_WORKER_NONE ||
 328                     pfp->pool[i].pid == 0) {
 329                         continue;
 330                 }
 331
 332                 pid = waitpid(pfp->pool[i].pid, &status, WNOHANG);
 333                 if (pid > 0) {
 334
 335                         if (pfp->pool[i].status != PF_WORKER_EXITING) {
 336                                 DEBUG(3, ("Child (%d) terminated abnormally:"
 337                                           " %d\n", (int)pid, status));
 338                         } else {
 339                                 DEBUG(10, ("Child (%d) terminated with status:"
 340                                            " %d\n", (int)pid, status));
 341                         }
 342
 343                         /* reset all fields,
 344                          * this makes status = PF_WORK_NONE */
 345                         memset(&pfp->pool[i], 0,
 346                                 sizeof(struct pf_worker_data));
 347                 }
 348         }
 349
 350 }
 351
 352 int prefork_count_allowed_connections(struct prefork_pool *pfp)
 353 {
 354         int c;
 355         int i;
 356
 357         c = 0;
 358         for (i = 0; i < pfp->pool_size; i++) {
 359                 if (pfp->pool[i].status == PF_WORKER_NONE ||
 360                     pfp->pool[i].status == PF_WORKER_EXITING) {
 361                         continue;
 362                 }
 363
 364                 if (pfp->pool[i].num_clients < 0) {
 365                         continue;
 366                 }
 367
 368                 c += pfp->pool[i].allowed_clients - pfp->pool[i].num_clients;
 369         }
 370
 371         return c;
 372 }
 373
 374 void prefork_increase_allowed_clients(struct prefork_pool *pfp, int max)
 375 {
 376         int i;
 377
 378         for (i = 0; i < pfp->pool_size; i++) {
 379                 if (pfp->pool[i].status == PF_WORKER_NONE ||
 380                     pfp->pool[i].status == PF_WORKER_EXITING) {
 381                         continue;
 382                 }
 383
 384                 if (pfp->pool[i].num_clients < 0) {
 385                         continue;
 386                 }
 387
 388                 if (pfp->pool[i].allowed_clients < max) {
 389                         pfp->pool[i].allowed_clients++;
 390                 }
 391         }
 392 }
 393
 394 void prefork_decrease_allowed_clients(struct prefork_pool *pfp)
 395 {
 396         int i;
 397
 398         for (i = 0; i < pfp->pool_size; i++) {
 399                 if (pfp->pool[i].status == PF_WORKER_NONE ||
 400                     pfp->pool[i].status == PF_WORKER_EXITING) {
 401                         continue;
 402                 }
 403
 404                 if (pfp->pool[i].num_clients < 0) {
 405                         continue;
 406                 }
 407
 408                 if (pfp->pool[i].allowed_clients > 1) {
 409                         pfp->pool[i].allowed_clients--;
 410                 }
 411         }
 412 }
 413
 414 void prefork_reset_allowed_clients(struct prefork_pool *pfp)
 415 {
 416         int i;
 417
 418         for (i = 0; i < pfp->pool_size; i++) {
 419                 pfp->pool[i].allowed_clients = 1;
 420         }
 421 }
 422
 423 void prefork_send_signal_to_all(struct prefork_pool *pfp, int signal_num)
 424 {
 425         int i;
 426
 427         for (i = 0; i < pfp->pool_size; i++) {
 428                 if (pfp->pool[i].status == PF_WORKER_NONE) {
 429                         continue;
 430                 }
 431
 432                 kill(pfp->pool[i].pid, signal_num);
 433         }
 434 }
 435
 436 void prefork_warn_active_children(struct messaging_context *msg_ctx,
 437                                   struct prefork_pool *pfp)
 438 {
 439         const DATA_BLOB ping = data_blob_null;
 440         int i;
 441
 442         for (i = 0; i < pfp->pool_size; i++) {
 443                 if (pfp->pool[i].status == PF_WORKER_NONE) {
 444                         continue;
 445                 }
 446
 447                 messaging_send(msg_ctx,
 448                                 pid_to_procid(pfp->pool[i].pid),
 449                                 MSG_PREFORK_PARENT_EVENT, &ping);
 450         }
 451 }
 452
 453 static void prefork_sigchld_handler(struct tevent_context *ev_ctx,
 454                                     struct tevent_signal *se,
 455                                     int signum, int count,
 456                                     void *siginfo, void *pvt)
 457 {
 458         struct prefork_pool *pfp;
 459
 460         pfp = talloc_get_type_abort(pvt, struct prefork_pool);
 461
 462         /* run the cleanup function to make sure all dead children are
 463          * properly and timely retired. */
 464         prefork_cleanup_loop(pfp);
 465
 466         if (pfp->sigchld_fn) {
 467                 pfp->sigchld_fn(ev_ctx, pfp, pfp->sigchld_data);
 468         }
 469 }
 470
 471 static bool prefork_setup_sigchld_handler(struct tevent_context *ev_ctx,
 472                                           struct prefork_pool *pfp)
 473 {
 474         struct tevent_signal *se;
 475
 476         se = tevent_add_signal(ev_ctx, pfp, SIGCHLD, 0,
 477                                 prefork_sigchld_handler, pfp);
 478         if (!se) {
 479                 DEBUG(0, ("Failed to setup SIGCHLD handler!\n"));
 480                 return false;
 481         }
 482
 483         return true;
 484 }
 485
 486 void prefork_set_sigchld_callback(struct prefork_pool *pfp,
 487                                   prefork_sigchld_fn_t *sigchld_fn,
 488                                   void *private_data)
 489 {
 490         pfp->sigchld_fn = sigchld_fn;
 491         pfp->sigchld_data = private_data;
 492 }
 493
 494 /* ==== Functions used by children ==== */
 495
 496 struct pf_listen_state {
 497         struct tevent_context *ev;
 498         struct pf_worker_data *pf;
 499
 500         int listen_fd_size;
 501         int *listen_fds;
 502
 503         int accept_fd;
 504
 505         struct tsocket_address *srv_addr;
 506         struct tsocket_address *cli_addr;
 507
 508         int error;
 509 };
 510
 511 struct pf_listen_ctx {
 512         TALLOC_CTX *fde_ctx;
 513         struct tevent_req *req;
 514         int listen_fd;
 515 };
 516
 517 static void prefork_listen_accept_handler(struct tevent_context *ev,
 518                                           struct tevent_fd *fde,
 519                                           uint16_t flags, void *pvt);
 520
 521 struct tevent_req *prefork_listen_send(TALLOC_CTX *mem_ctx,
 522                                         struct tevent_context *ev,
 523                                         struct pf_worker_data *pf,
 524                                         int listen_fd_size,
 525                                         int *listen_fds)
 526 {
 527         struct tevent_req *req;
 528         struct pf_listen_state *state;
 529         struct pf_listen_ctx *ctx;
 530         struct tevent_fd *fde;
 531         TALLOC_CTX *fde_ctx;
 532         int i;
 533
 534         req = tevent_req_create(mem_ctx, &state, struct pf_listen_state);
 535         if (!req) {
 536                 return NULL;
 537         }
 538
 539         state->ev = ev;
 540         state->pf = pf;
 541         state->listen_fd_size = listen_fd_size;
 542         state->listen_fds = listen_fds;
 543         state->accept_fd = -1;
 544         state->error = 0;
 545
 546         fde_ctx = talloc_new(state);
 547         if (tevent_req_nomem(fde_ctx, req)) {
 548                 return tevent_req_post(req, ev);
 549         }
 550
 551         /* race on accept */
 552         for (i = 0; i < state->listen_fd_size; i++) {
 553                 ctx = talloc(fde_ctx, struct pf_listen_ctx);
 554                 if (tevent_req_nomem(ctx, req)) {
 555                         return tevent_req_post(req, ev);
 556                 }
 557                 ctx->fde_ctx = fde_ctx;
 558                 ctx->req = req;
 559                 ctx->listen_fd = state->listen_fds[i];
 560
 561                 fde = tevent_add_fd(state->ev, fde_ctx,
 562                                     ctx->listen_fd, TEVENT_FD_READ,
 563                                     prefork_listen_accept_handler, ctx);
 564                 if (tevent_req_nomem(fde, req)) {
 565                         return tevent_req_post(req, ev);
 566                 }
 567         }
 568
 569         pf->status = PF_WORKER_ACCEPTING;
 570
 571         return req;
 572 }
 573
 574 static void prefork_listen_accept_handler(struct tevent_context *ev,
 575                                           struct tevent_fd *fde,
 576                                           uint16_t flags, void *pvt)
 577 {
 578         struct pf_listen_state *state;
 579         struct tevent_req *req;
 580         struct pf_listen_ctx *ctx;
 581         struct sockaddr_storage addr;
 582         socklen_t addrlen;
 583         int soerr = 0;
 584         socklen_t solen = sizeof(soerr);
 585         int sd = -1;
 586         int ret;
 587
 588         ctx = talloc_get_type_abort(pvt, struct pf_listen_ctx);
 589         req = ctx->req;
 590         state = tevent_req_data(ctx->req, struct pf_listen_state);
 591
 592         if ((state->pf->cmds == PF_SRV_MSG_EXIT) &&
 593             (state->pf->num_clients <= 0)) {
 594                 /* We have been asked to exit, so drop here and the next
 595                  * child will pick it up */
 596                 state->pf->status = PF_WORKER_EXITING;
 597                 state->error = EINTR;
 598                 goto done;
 599         }
 600
 601         /* before proceeding check that the listening fd is ok */
 602         ret = getsockopt(ctx->listen_fd, SOL_SOCKET, SO_ERROR, &soerr, &solen);
 603         if (ret == -1) {
 604                 /* this is a fatal error, we cannot continue listening */
 605                 state->error = EBADF;
 606                 goto done;
 607         }
 608         if (soerr != 0) {
 609                 /* this is a fatal error, we cannot continue listening */
 610                 state->error = soerr;
 611                 goto done;
 612         }
 613
 614         ZERO_STRUCT(addr);
 615         addrlen = sizeof(addr);
 616         sd = accept(ctx->listen_fd, (struct sockaddr *)&addr, &addrlen);
 617         if (sd == -1) {
 618                 state->error = errno;
 619                 DEBUG(6, ("Accept failed! (%d, %s)\n",
 620                           state->error, strerror(state->error)));
 621                 goto done;
 622         }
 623         smb_set_close_on_exec(sd);
 624
 625         state->accept_fd = sd;
 626
 627         ret = tsocket_address_bsd_from_sockaddr(state,
 628                                         (struct sockaddr *)(void *)&addr,
 629                                         addrlen, &state->cli_addr);
 630         if (ret < 0) {
 631                 state->error = errno;
 632                 goto done;
 633         }
 634
 635         ZERO_STRUCT(addr);
 636         addrlen = sizeof(addr);
 637         ret = getsockname(sd, (struct sockaddr *)(void *)&addr, &addrlen);
 638         if (ret < 0) {
 639                 state->error = errno;
 640                 goto done;
 641         }
 642
 643         ret = tsocket_address_bsd_from_sockaddr(state,
 644                                         (struct sockaddr *)(void *)&addr,
 645                                         addrlen, &state->srv_addr);
 646         if (ret < 0) {
 647                 state->error = errno;
 648                 goto done;
 649         }
 650
 651 done:
 652         /* do not track the listen fds anymore */
 653         talloc_free(ctx->fde_ctx);
 654         tevent_req_done(req);
 655 }
 656
 657 int prefork_listen_recv(struct tevent_req *req,
 658                         TALLOC_CTX *mem_ctx, int *fd,
 659                         struct tsocket_address **srv_addr,
 660                         struct tsocket_address **cli_addr)
 661 {
 662         struct pf_listen_state *state;
 663         int ret = 0;
 664
 665         state = tevent_req_data(req, struct pf_listen_state);
 666
 667         if (state->error) {
 668                 ret = state->error;
 669         } else {
 670                 if (!tevent_req_is_unix_error(req, &ret)) {
 671                         ret = 0;
 672                 }
 673         }
 674
 675         if (ret) {
 676                 if (state->accept_fd != -1) {
 677                         close(state->accept_fd);
 678                 }
 679         } else {
 680                 *fd = state->accept_fd;
 681                 *srv_addr = talloc_move(mem_ctx, &state->srv_addr);
 682                 *cli_addr = talloc_move(mem_ctx, &state->cli_addr);
 683                 state->pf->num_clients++;
 684         }
 685         if (state->pf->status == PF_WORKER_ACCEPTING) {
 686                 state->pf->status = PF_WORKER_ALIVE;
 687         }
 688
 689         tevent_req_received(req);
 690         return ret;
 691 }