src/core/cgroup.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <assert.h>
  24 #include <unistd.h>
  25 #include <sys/types.h>
  26 #include <signal.h>
  27 #include <sys/mount.h>
  28 #include <fcntl.h>
  29
  30 #include "cgroup.h"
  31 #include "cgroup-util.h"
  32 #include "log.h"
  33 #include "strv.h"
  34 #include "path-util.h"
  35
  36 int cgroup_bonding_realize(CGroupBonding *b) {
  37         int r;
  38
  39         assert(b);
  40         assert(b->path);
  41         assert(b->controller);
  42
  43         r = cg_create(b->controller, b->path);
  44         if (r < 0) {
  45                 log_warning("Failed to create cgroup %s:%s: %s", b->controller, b->path, strerror(-r));
  46                 return r;
  47         }
  48
  49         b->realized = true;
  50
  51         return 0;
  52 }
  53
  54 int cgroup_bonding_realize_list(CGroupBonding *first) {
  55         CGroupBonding *b;
  56         int r;
  57
  58         LIST_FOREACH(by_unit, b, first)
  59                 if ((r = cgroup_bonding_realize(b)) < 0 && b->essential)
  60                         return r;
  61
  62         return 0;
  63 }
  64
  65 void cgroup_bonding_free(CGroupBonding *b, bool trim) {
  66         assert(b);
  67
  68         if (b->unit) {
  69                 CGroupBonding *f;
  70
  71                 LIST_REMOVE(CGroupBonding, by_unit, b->unit->cgroup_bondings, b);
  72
  73                 if (streq(b->controller, SYSTEMD_CGROUP_CONTROLLER)) {
  74                         assert_se(f = hashmap_get(b->unit->manager->cgroup_bondings, b->path));
  75                         LIST_REMOVE(CGroupBonding, by_path, f, b);
  76
  77                         if (f)
  78                                 hashmap_replace(b->unit->manager->cgroup_bondings, b->path, f);
  79                         else
  80                                 hashmap_remove(b->unit->manager->cgroup_bondings, b->path);
  81                 }
  82         }
  83
  84         if (b->realized && b->ours && trim)
  85                 cg_trim(b->controller, b->path, false);
  86
  87         free(b->controller);
  88         free(b->path);
  89         free(b);
  90 }
  91
  92 void cgroup_bonding_free_list(CGroupBonding *first, bool remove_or_trim) {
  93         CGroupBonding *b, *n;
  94
  95         LIST_FOREACH_SAFE(by_unit, b, n, first)
  96                 cgroup_bonding_free(b, remove_or_trim);
  97 }
  98
  99 void cgroup_bonding_trim(CGroupBonding *b, bool delete_root) {
 100         assert(b);
 101
 102         if (b->realized && b->ours)
 103                 cg_trim(b->controller, b->path, delete_root);
 104 }
 105
 106 void cgroup_bonding_trim_list(CGroupBonding *first, bool delete_root) {
 107         CGroupBonding *b;
 108
 109         LIST_FOREACH(by_unit, b, first)
 110                 cgroup_bonding_trim(b, delete_root);
 111 }
 112
 113
 114 int cgroup_bonding_install(CGroupBonding *b, pid_t pid, const char *cgroup_suffix) {
 115         char *p = NULL;
 116         const char *path;
 117         int r;
 118
 119         assert(b);
 120         assert(pid >= 0);
 121
 122         if (cgroup_suffix) {
 123                 p = strjoin(b->path, "/", cgroup_suffix, NULL);
 124                 if (!p)
 125                         return -ENOMEM;
 126
 127                 path = p;
 128         } else
 129                 path = b->path;
 130
 131         r = cg_create_and_attach(b->controller, path, pid);
 132         free(p);
 133
 134         if (r < 0)
 135                 return r;
 136
 137         b->realized = true;
 138         return 0;
 139 }
 140
 141 int cgroup_bonding_install_list(CGroupBonding *first, pid_t pid, const char *cgroup_suffix) {
 142         CGroupBonding *b;
 143         int r;
 144
 145         LIST_FOREACH(by_unit, b, first) {
 146                 r = cgroup_bonding_install(b, pid, cgroup_suffix);
 147                 if (r < 0 && b->essential)
 148                         return r;
 149         }
 150
 151         return 0;
 152 }
 153
 154 int cgroup_bonding_set_group_access(CGroupBonding *b, mode_t mode, uid_t uid, gid_t gid) {
 155         assert(b);
 156
 157         if (!b->realized)
 158                 return -EINVAL;
 159
 160         return cg_set_group_access(b->controller, b->path, mode, uid, gid);
 161 }
 162
 163 int cgroup_bonding_set_group_access_list(CGroupBonding *first, mode_t mode, uid_t uid, gid_t gid) {
 164         CGroupBonding *b;
 165         int r;
 166
 167         LIST_FOREACH(by_unit, b, first) {
 168                 r = cgroup_bonding_set_group_access(b, mode, uid, gid);
 169                 if (r < 0)
 170                         return r;
 171         }
 172
 173         return 0;
 174 }
 175
 176 int cgroup_bonding_set_task_access(CGroupBonding *b, mode_t mode, uid_t uid, gid_t gid, int sticky) {
 177         assert(b);
 178
 179         if (!b->realized)
 180                 return -EINVAL;
 181
 182         return cg_set_task_access(b->controller, b->path, mode, uid, gid, sticky);
 183 }
 184
 185 int cgroup_bonding_set_task_access_list(CGroupBonding *first, mode_t mode, uid_t uid, gid_t gid, int sticky) {
 186         CGroupBonding *b;
 187         int r;
 188
 189         LIST_FOREACH(by_unit, b, first) {
 190                 r = cgroup_bonding_set_task_access(b, mode, uid, gid, sticky);
 191                 if (r < 0)
 192                         return r;
 193         }
 194
 195         return 0;
 196 }
 197
 198 int cgroup_bonding_kill(CGroupBonding *b, int sig, bool sigcont, bool rem, Set *s, const char *cgroup_suffix) {
 199         char *p = NULL;
 200         const char *path;
 201         int r;
 202
 203         assert(b);
 204         assert(sig >= 0);
 205
 206         /* Don't kill cgroups that aren't ours */
 207         if (!b->ours)
 208                 return 0;
 209
 210         if (cgroup_suffix) {
 211                 p = strjoin(b->path, "/", cgroup_suffix, NULL);
 212                 if (!p)
 213                         return -ENOMEM;
 214
 215                 path = p;
 216         } else
 217                 path = b->path;
 218
 219         r = cg_kill_recursive(b->controller, path, sig, sigcont, true, rem, s);
 220         free(p);
 221
 222         return r;
 223 }
 224
 225 int cgroup_bonding_kill_list(CGroupBonding *first, int sig, bool sigcont, bool rem, Set *s, const char *cgroup_suffix) {
 226         CGroupBonding *b;
 227         Set *allocated_set = NULL;
 228         int ret = -EAGAIN, r;
 229
 230         if (!first)
 231                 return 0;
 232
 233         if (!s)
 234                 if (!(s = allocated_set = set_new(trivial_hash_func, trivial_compare_func)))
 235                         return -ENOMEM;
 236
 237         LIST_FOREACH(by_unit, b, first) {
 238                 r = cgroup_bonding_kill(b, sig, sigcont, rem, s, cgroup_suffix);
 239                 if (r < 0) {
 240                         if (r == -EAGAIN || r == -ESRCH)
 241                                 continue;
 242
 243                         ret = r;
 244                         goto finish;
 245                 }
 246
 247                 if (ret < 0 || r > 0)
 248                         ret = r;
 249         }
 250
 251 finish:
 252         if (allocated_set)
 253                 set_free(allocated_set);
 254
 255         return ret;
 256 }
 257
 258 /* Returns 1 if the group is empty, 0 if it is not, -EAGAIN if we
 259  * cannot know */
 260 int cgroup_bonding_is_empty(CGroupBonding *b) {
 261         int r;
 262
 263         assert(b);
 264
 265         if ((r = cg_is_empty_recursive(b->controller, b->path, true)) < 0)
 266                 return r;
 267
 268         /* If it is empty it is empty */
 269         if (r > 0)
 270                 return 1;
 271
 272         /* It's not only us using this cgroup, so we just don't know */
 273         return b->ours ? 0 : -EAGAIN;
 274 }
 275
 276 int cgroup_bonding_is_empty_list(CGroupBonding *first) {
 277         CGroupBonding *b;
 278
 279         LIST_FOREACH(by_unit, b, first) {
 280                 int r;
 281
 282                 if ((r = cgroup_bonding_is_empty(b)) < 0) {
 283                         /* If this returned -EAGAIN, then we don't know if the
 284                          * group is empty, so let's see if another group can
 285                          * tell us */
 286
 287                         if (r != -EAGAIN)
 288                                 return r;
 289                 } else
 290                         return r;
 291         }
 292
 293         return -EAGAIN;
 294 }
 295
 296 int manager_setup_cgroup(Manager *m) {
 297         char *current = NULL, *path = NULL;
 298         int r;
 299         char suffix[32];
 300
 301         assert(m);
 302
 303         /* 0. Be nice to Ingo Molnar #628004 */
 304         if (path_is_mount_point("/sys/fs/cgroup/systemd", false) <= 0) {
 305                 log_warning("No control group support available, not creating root group.");
 306                 return 0;
 307         }
 308
 309         /* 1. Determine hierarchy */
 310         r = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &current);
 311         if (r < 0) {
 312                 log_error("Cannot determine cgroup we are running in: %s", strerror(-r));
 313                 goto finish;
 314         }
 315
 316         if (m->running_as == MANAGER_SYSTEM)
 317                 strcpy(suffix, "/system");
 318         else {
 319                 snprintf(suffix, sizeof(suffix), "/systemd-%lu", (unsigned long) getpid());
 320                 char_array_0(suffix);
 321         }
 322
 323         free(m->cgroup_hierarchy);
 324         if (endswith(current, suffix)) {
 325                 /* We probably got reexecuted and can continue to use our root cgroup */
 326                 m->cgroup_hierarchy = current;
 327                 current = NULL;
 328
 329         } else {
 330                 /* We need a new root cgroup */
 331                 m->cgroup_hierarchy = NULL;
 332                 if (asprintf(&m->cgroup_hierarchy, "%s%s", streq(current, "/") ? "" : current, suffix) < 0) {
 333                         log_error("Out of memory.");
 334                         r = -ENOMEM;
 335                         goto finish;
 336                 }
 337         }
 338
 339         /* 2. Show data */
 340         r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy, NULL, &path);
 341         if (r < 0) {
 342                 log_error("Cannot find cgroup mount point: %s", strerror(-r));
 343                 goto finish;
 344         }
 345
 346         log_debug("Using cgroup controller " SYSTEMD_CGROUP_CONTROLLER ". File system hierarchy is at %s.", path);
 347
 348         /* 3. Install agent */
 349         r = cg_install_release_agent(SYSTEMD_CGROUP_CONTROLLER, SYSTEMD_CGROUP_AGENT_PATH);
 350         if (r < 0)
 351                 log_warning("Failed to install release agent, ignoring: %s", strerror(-r));
 352         else if (r > 0)
 353                 log_debug("Installed release agent.");
 354         else
 355                 log_debug("Release agent already installed.");
 356
 357         /* 4. Realize the group */
 358         r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy, 0);
 359         if (r < 0) {
 360                 log_error("Failed to create root cgroup hierarchy: %s", strerror(-r));
 361                 goto finish;
 362         }
 363
 364         /* 5. And pin it, so that it cannot be unmounted */
 365         if (m->pin_cgroupfs_fd >= 0)
 366                 close_nointr_nofail(m->pin_cgroupfs_fd);
 367
 368         m->pin_cgroupfs_fd = open(path, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOCTTY|O_NONBLOCK);
 369         if (r < 0) {
 370                 log_error("Failed to open pin file: %m");
 371                 r = -errno;
 372                 goto finish;
 373         }
 374
 375         log_debug("Created root group.");
 376
 377         cg_shorten_controllers(m->default_controllers);
 378
 379 finish:
 380         free(current);
 381         free(path);
 382
 383         return r;
 384 }
 385
 386 void manager_shutdown_cgroup(Manager *m, bool delete) {
 387         assert(m);
 388
 389         if (delete && m->cgroup_hierarchy)
 390                 cg_delete(SYSTEMD_CGROUP_CONTROLLER, m->cgroup_hierarchy);
 391
 392         if (m->pin_cgroupfs_fd >= 0) {
 393                 close_nointr_nofail(m->pin_cgroupfs_fd);
 394                 m->pin_cgroupfs_fd = -1;
 395         }
 396
 397         free(m->cgroup_hierarchy);
 398         m->cgroup_hierarchy = NULL;
 399 }
 400
 401 int cgroup_bonding_get(Manager *m, const char *cgroup, CGroupBonding **bonding) {
 402         CGroupBonding *b;
 403         char *p;
 404
 405         assert(m);
 406         assert(cgroup);
 407         assert(bonding);
 408
 409         b = hashmap_get(m->cgroup_bondings, cgroup);
 410         if (b) {
 411                 *bonding = b;
 412                 return 1;
 413         }
 414
 415         p = strdup(cgroup);
 416         if (!p)
 417                 return -ENOMEM;
 418
 419         for (;;) {
 420                 char *e;
 421
 422                 e = strrchr(p, '/');
 423                 if (!e || e == p) {
 424                         free(p);
 425                         *bonding = NULL;
 426                         return 0;
 427                 }
 428
 429                 *e = 0;
 430
 431                 b = hashmap_get(m->cgroup_bondings, p);
 432                 if (b) {
 433                         free(p);
 434                         *bonding = b;
 435                         return 1;
 436                 }
 437         }
 438 }
 439
 440 int cgroup_notify_empty(Manager *m, const char *group) {
 441         CGroupBonding *l, *b;
 442         int r;
 443
 444         assert(m);
 445         assert(group);
 446
 447         r = cgroup_bonding_get(m, group, &l);
 448         if (r <= 0)
 449                 return r;
 450
 451         LIST_FOREACH(by_path, b, l) {
 452                 int t;
 453
 454                 if (!b->unit)
 455                         continue;
 456
 457                 t = cgroup_bonding_is_empty_list(b);
 458                 if (t < 0) {
 459
 460                         /* If we don't know, we don't know */
 461                         if (t != -EAGAIN)
 462                                 log_warning("Failed to check whether cgroup is empty: %s", strerror(errno));
 463
 464                         continue;
 465                 }
 466
 467                 if (t > 0) {
 468                         /* If it is empty, let's delete it */
 469                         cgroup_bonding_trim_list(b->unit->cgroup_bondings, true);
 470
 471                         if (UNIT_VTABLE(b->unit)->cgroup_notify_empty)
 472                                 UNIT_VTABLE(b->unit)->cgroup_notify_empty(b->unit);
 473                 }
 474         }
 475
 476         return 0;
 477 }
 478
 479 Unit* cgroup_unit_by_pid(Manager *m, pid_t pid) {
 480         CGroupBonding *l, *b;
 481         char *group = NULL;
 482
 483         assert(m);
 484
 485         if (pid <= 1)
 486                 return NULL;
 487
 488         if (cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, pid, &group) < 0)
 489                 return NULL;
 490
 491         l = hashmap_get(m->cgroup_bondings, group);
 492
 493         if (!l) {
 494                 char *slash;
 495
 496                 while ((slash = strrchr(group, '/'))) {
 497                         if (slash == group)
 498                                 break;
 499
 500                         *slash = 0;
 501
 502                         if ((l = hashmap_get(m->cgroup_bondings, group)))
 503                                 break;
 504                 }
 505         }
 506
 507         free(group);
 508
 509         LIST_FOREACH(by_path, b, l) {
 510
 511                 if (!b->unit)
 512                         continue;
 513
 514                 if (b->ours)
 515                         return b->unit;
 516         }
 517
 518         return NULL;
 519 }
 520
 521 CGroupBonding *cgroup_bonding_find_list(CGroupBonding *first, const char *controller) {
 522         CGroupBonding *b;
 523
 524         assert(controller);
 525
 526         LIST_FOREACH(by_unit, b, first)
 527                 if (streq(b->controller, controller))
 528                         return b;
 529
 530         return NULL;
 531 }
 532
 533 char *cgroup_bonding_to_string(CGroupBonding *b) {
 534         char *r;
 535
 536         assert(b);
 537
 538         if (asprintf(&r, "%s:%s", b->controller, b->path) < 0)
 539                 return NULL;
 540
 541         return r;
 542 }
 543
 544 pid_t cgroup_bonding_search_main_pid(CGroupBonding *b) {
 545         FILE *f;
 546         pid_t pid = 0, npid, mypid;
 547
 548         assert(b);
 549
 550         if (!b->ours)
 551                 return 0;
 552
 553         if (cg_enumerate_processes(b->controller, b->path, &f) < 0)
 554                 return 0;
 555
 556         mypid = getpid();
 557
 558         while (cg_read_pid(f, &npid) > 0)  {
 559                 pid_t ppid;
 560
 561                 if (npid == pid)
 562                         continue;
 563
 564                 /* Ignore processes that aren't our kids */
 565                 if (get_parent_of_pid(npid, &ppid) >= 0 && ppid != mypid)
 566                         continue;
 567
 568                 if (pid != 0) {
 569                         /* Dang, there's more than one daemonized PID
 570                         in this group, so we don't know what process
 571                         is the main process. */
 572                         pid = 0;
 573                         break;
 574                 }
 575
 576                 pid = npid;
 577         }
 578
 579         fclose(f);
 580
 581         return pid;
 582 }
 583
 584 pid_t cgroup_bonding_search_main_pid_list(CGroupBonding *first) {
 585         CGroupBonding *b;
 586         pid_t pid;
 587
 588         /* Try to find a main pid from this cgroup, but checking if
 589          * there's only one PID in the cgroup and returning it. Later
 590          * on we might want to add additional, smarter heuristics
 591          * here. */
 592
 593         LIST_FOREACH(by_unit, b, first)
 594                 if ((pid = cgroup_bonding_search_main_pid(b)) != 0)
 595                         return pid;
 596
 597         return 0;
 598
 599 }