/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include #include #include #include #include #include #include #include #include #include "alloc-util.h" #include "cgroup-util.h" #include "constants.h" #include "dirent-util.h" #include "extract-word.h" #include "fd-util.h" #include "fileio.h" #include "format-util.h" #include "fs-util.h" #include "log.h" #include "login-util.h" #include "macro.h" #include "missing_magic.h" #include "missing_threads.h" #include "mkdir.h" #include "parse-util.h" #include "path-util.h" #include "process-util.h" #include "set.h" #include "special.h" #include "stat-util.h" #include "stdio-util.h" #include "string-table.h" #include "string-util.h" #include "strv.h" #include "unit-name.h" #include "user-util.h" #include "xattr-util.h" static int cg_enumerate_items(const char *controller, const char *path, FILE **_f, const char *item) { _cleanup_free_ char *fs = NULL; FILE *f; int r; assert(_f); r = cg_get_path(controller, path, item, &fs); if (r < 0) return r; f = fopen(fs, "re"); if (!f) return -errno; *_f = f; return 0; } int cg_enumerate_processes(const char *controller, const char *path, FILE **_f) { return cg_enumerate_items(controller, path, _f, "cgroup.procs"); } int cg_read_pid(FILE *f, pid_t *_pid) { unsigned long ul; /* Note that the cgroup.procs might contain duplicates! See * cgroups.txt for details. */ assert(f); assert(_pid); errno = 0; if (fscanf(f, "%lu", &ul) != 1) { if (feof(f)) return 0; return errno_or_else(EIO); } if (ul <= 0) return -EIO; *_pid = (pid_t) ul; return 1; } int cg_read_event( const char *controller, const char *path, const char *event, char **ret) { _cleanup_free_ char *events = NULL, *content = NULL; int r; r = cg_get_path(controller, path, "cgroup.events", &events); if (r < 0) return r; r = read_full_virtual_file(events, &content, NULL); if (r < 0) return r; for (const char *p = content;;) { _cleanup_free_ char *line = NULL, *key = NULL, *val = NULL; const char *q; r = extract_first_word(&p, &line, "\n", 0); if (r < 0) return r; if (r == 0) return -ENOENT; q = line; r = extract_first_word(&q, &key, " ", 0); if (r < 0) return r; if (r == 0) return -EINVAL; if (!streq(key, event)) continue; val = strdup(q); if (!val) return -ENOMEM; *ret = TAKE_PTR(val); return 0; } } bool cg_ns_supported(void) { static thread_local int enabled = -1; if (enabled >= 0) return enabled; if (access("/proc/self/ns/cgroup", F_OK) < 0) { if (errno != ENOENT) log_debug_errno(errno, "Failed to check whether /proc/self/ns/cgroup is available, assuming not: %m"); enabled = false; } else enabled = true; return enabled; } bool cg_freezer_supported(void) { static thread_local int supported = -1; if (supported >= 0) return supported; supported = cg_all_unified() > 0 && access("/sys/fs/cgroup/init.scope/cgroup.freeze", F_OK) == 0; return supported; } bool cg_kill_supported(void) { static thread_local int supported = -1; if (supported >= 0) return supported; if (cg_all_unified() <= 0) supported = false; else if (access("/sys/fs/cgroup/init.scope/cgroup.kill", F_OK) < 0) { if (errno != ENOENT) log_debug_errno(errno, "Failed to check if cgroup.kill is available, assuming not: %m"); supported = false; } else supported = true; return supported; } int cg_enumerate_subgroups(const char *controller, const char *path, DIR **_d) { _cleanup_free_ char *fs = NULL; int r; DIR *d; assert(_d); /* This is not recursive! */ r = cg_get_path(controller, path, NULL, &fs); if (r < 0) return r; d = opendir(fs); if (!d) return -errno; *_d = d; return 0; } int cg_read_subgroup(DIR *d, char **fn) { assert(d); assert(fn); FOREACH_DIRENT_ALL(de, d, return -errno) { char *b; if (de->d_type != DT_DIR) continue; if (dot_or_dot_dot(de->d_name)) continue; b = strdup(de->d_name); if (!b) return -ENOMEM; *fn = b; return 1; } return 0; } int cg_rmdir(const char *controller, const char *path) { _cleanup_free_ char *p = NULL; int r; r = cg_get_path(controller, path, NULL, &p); if (r < 0) return r; r = rmdir(p); if (r < 0 && errno != ENOENT) return -errno; r = cg_hybrid_unified(); if (r <= 0) return r; if (streq(controller, SYSTEMD_CGROUP_CONTROLLER)) { r = cg_rmdir(SYSTEMD_CGROUP_CONTROLLER_LEGACY, path); if (r < 0) log_warning_errno(r, "Failed to remove compat systemd cgroup %s: %m", path); } return 0; } static int cg_kill_items( const char *controller, const char *path, int sig, CGroupFlags flags, Set *s, cg_kill_log_func_t log_kill, void *userdata, const char *item) { _cleanup_set_free_ Set *allocated_set = NULL; bool done = false; int r, ret = 0, ret_log_kill = 0; pid_t my_pid; assert(sig >= 0); /* Don't send SIGCONT twice. Also, SIGKILL always works even when process is suspended, hence don't send * SIGCONT on SIGKILL. */ if (IN_SET(sig, SIGCONT, SIGKILL)) flags &= ~CGROUP_SIGCONT; /* This goes through the tasks list and kills them all. This * is repeated until no further processes are added to the * tasks list, to properly handle forking processes */ if (!s) { s = allocated_set = set_new(NULL); if (!s) return -ENOMEM; } my_pid = getpid_cached(); do { _cleanup_fclose_ FILE *f = NULL; pid_t pid = 0; done = true; r = cg_enumerate_items(controller, path, &f, item); if (r < 0) { if (ret >= 0 && r != -ENOENT) return r; return ret; } while ((r = cg_read_pid(f, &pid)) > 0) { if ((flags & CGROUP_IGNORE_SELF) && pid == my_pid) continue; if (set_get(s, PID_TO_PTR(pid)) == PID_TO_PTR(pid)) continue; if (log_kill) ret_log_kill = log_kill(pid, sig, userdata); /* If we haven't killed this process yet, kill * it */ if (kill(pid, sig) < 0) { if (ret >= 0 && errno != ESRCH) ret = -errno; } else { if (flags & CGROUP_SIGCONT) (void) kill(pid, SIGCONT); if (ret == 0) { if (log_kill) ret = ret_log_kill; else ret = 1; } } done = false; r = set_put(s, PID_TO_PTR(pid)); if (r < 0) { if (ret >= 0) return r; return ret; } } if (r < 0) { if (ret >= 0) return r; return ret; } /* To avoid racing against processes which fork * quicker than we can kill them we repeat this until * no new pids need to be killed. */ } while (!done); return ret; } int cg_kill( const char *controller, const char *path, int sig, CGroupFlags flags, Set *s, cg_kill_log_func_t log_kill, void *userdata) { int r, ret; r = cg_kill_items(controller, path, sig, flags, s, log_kill, userdata, "cgroup.procs"); if (r < 0 || sig != SIGKILL) return r; ret = r; /* Only in case of killing with SIGKILL and when using cgroupsv2, kill remaining threads manually as a workaround for kernel bug. It was fixed in 5.2-rc5 (c03cd7738a83), backported to 4.19.66 (4340d175b898) and 4.14.138 (feb6b123b7dd). */ r = cg_unified_controller(controller); if (r < 0) return r; if (r == 0) return ret; r = cg_kill_items(controller, path, sig, flags, s, log_kill, userdata, "cgroup.threads"); if (r < 0) return r; return r > 0 || ret > 0; } int cg_kill_kernel_sigkill(const char *controller, const char *path) { /* Kills the cgroup at `path` directly by writing to its cgroup.kill file. * This sends SIGKILL to all processes in the cgroup and has the advantage of * being completely atomic, unlike cg_kill_items. */ int r; _cleanup_free_ char *killfile = NULL; assert(path); if (!cg_kill_supported()) return -EOPNOTSUPP; r = cg_get_path(controller, path, "cgroup.kill", &killfile); if (r < 0) return r; r = write_string_file(killfile, "1", WRITE_STRING_FILE_DISABLE_BUFFER); if (r < 0) return r; return 0; } int cg_kill_recursive( const char *controller, const char *path, int sig, CGroupFlags flags, Set *s, cg_kill_log_func_t log_kill, void *userdata) { _cleanup_set_free_ Set *allocated_set = NULL; _cleanup_closedir_ DIR *d = NULL; int r, ret; char *fn; assert(path); assert(sig >= 0); if (sig == SIGKILL && cg_kill_supported() && !FLAGS_SET(flags, CGROUP_IGNORE_SELF) && !s && !log_kill) { /* ignore CGROUP_SIGCONT, since this is a no-op alongside SIGKILL */ ret = cg_kill_kernel_sigkill(controller, path); if (ret < 0) return ret; } else { if (!s) { s = allocated_set = set_new(NULL); if (!s) return -ENOMEM; } ret = cg_kill(controller, path, sig, flags, s, log_kill, userdata); r = cg_enumerate_subgroups(controller, path, &d); if (r < 0) { if (ret >= 0 && r != -ENOENT) return r; return ret; } while ((r = cg_read_subgroup(d, &fn)) > 0) { _cleanup_free_ char *p = NULL; p = path_join(empty_to_root(path), fn); free(fn); if (!p) return -ENOMEM; r = cg_kill_recursive(controller, p, sig, flags, s, log_kill, userdata); if (r != 0 && ret >= 0) ret = r; } if (ret >= 0 && r < 0) ret = r; } if (FLAGS_SET(flags, CGROUP_REMOVE)) { r = cg_rmdir(controller, path); if (r < 0 && ret >= 0 && !IN_SET(r, -ENOENT, -EBUSY)) return r; } return ret; } static const char *controller_to_dirname(const char *controller) { assert(controller); /* Converts a controller name to the directory name below /sys/fs/cgroup/ we want to mount it * to. Effectively, this just cuts off the name= prefixed used for named hierarchies, if it is * specified. */ if (streq(controller, SYSTEMD_CGROUP_CONTROLLER)) { if (cg_hybrid_unified() > 0) controller = SYSTEMD_CGROUP_CONTROLLER_HYBRID; else controller = SYSTEMD_CGROUP_CONTROLLER_LEGACY; } return startswith(controller, "name=") ?: controller; } static int join_path_legacy(const char *controller, const char *path, const char *suffix, char **ret) { const char *dn; char *t = NULL; assert(ret); assert(controller); dn = controller_to_dirname(controller); if (isempty(path) && isempty(suffix)) t = path_join("/sys/fs/cgroup", dn); else if (isempty(path)) t = path_join("/sys/fs/cgroup", dn, suffix); else if (isempty(suffix)) t = path_join("/sys/fs/cgroup", dn, path); else t = path_join("/sys/fs/cgroup", dn, path, suffix); if (!t) return -ENOMEM; *ret = t; return 0; } static int join_path_unified(const char *path, const char *suffix, char **ret) { char *t; assert(ret); if (isempty(path) && isempty(suffix)) t = strdup("/sys/fs/cgroup"); else if (isempty(path)) t = path_join("/sys/fs/cgroup", suffix); else if (isempty(suffix)) t = path_join("/sys/fs/cgroup", path); else t = path_join("/sys/fs/cgroup", path, suffix); if (!t) return -ENOMEM; *ret = t; return 0; } int cg_get_path(const char *controller, const char *path, const char *suffix, char **ret) { int r; assert(ret); if (!controller) { char *t; /* If no controller is specified, we return the path *below* the controllers, without any * prefix. */ if (isempty(path) && isempty(suffix)) return -EINVAL; if (isempty(suffix)) t = strdup(path); else if (isempty(path)) t = strdup(suffix); else t = path_join(path, suffix); if (!t) return -ENOMEM; *ret = path_simplify(t); return 0; } if (!cg_controller_is_valid(controller)) return -EINVAL; r = cg_all_unified(); if (r < 0) return r; if (r > 0) r = join_path_unified(path, suffix, ret); else r = join_path_legacy(controller, path, suffix, ret); if (r < 0) return r; path_simplify(*ret); return 0; } static int controller_is_v1_accessible(const char *root, const char *controller) { const char *cpath, *dn; assert(controller); dn = controller_to_dirname(controller); /* If root if specified, we check that: * - possible subcgroup is created at root, * - we can modify the hierarchy. */ cpath = strjoina("/sys/fs/cgroup/", dn, root, root ? "/cgroup.procs" : NULL); return laccess(cpath, root ? W_OK : F_OK); } int cg_get_path_and_check(const char *controller, const char *path, const char *suffix, char **fs) { int r; assert(controller); assert(fs); if (!cg_controller_is_valid(controller)) return -EINVAL; r = cg_all_unified(); if (r < 0) return r; if (r > 0) { /* In the unified hierarchy all controllers are considered accessible, * except for the named hierarchies */ if (startswith(controller, "name=")) return -EOPNOTSUPP; } else { /* Check if the specified controller is actually accessible */ r = controller_is_v1_accessible(NULL, controller); if (r < 0) return r; } return cg_get_path(controller, path, suffix, fs); } int cg_set_xattr(const char *controller, const char *path, const char *name, const void *value, size_t size, int flags) { _cleanup_free_ char *fs = NULL; int r; assert(path); assert(name); assert(value || size <= 0); r = cg_get_path(controller, path, NULL, &fs); if (r < 0) return r; return RET_NERRNO(setxattr(fs, name, value, size, flags)); } int cg_get_xattr(const char *controller, const char *path, const char *name, void *value, size_t size) { _cleanup_free_ char *fs = NULL; ssize_t n; int r; assert(path); assert(name); r = cg_get_path(controller, path, NULL, &fs); if (r < 0) return r; n = getxattr(fs, name, value, size); if (n < 0) return -errno; return (int) n; } int cg_get_xattr_malloc(const char *controller, const char *path, const char *name, char **ret) { _cleanup_free_ char *fs = NULL; int r; assert(path); assert(name); r = cg_get_path(controller, path, NULL, &fs); if (r < 0) return r; r = lgetxattr_malloc(fs, name, ret); if (r < 0) return r; return r; } int cg_get_xattr_bool(const char *controller, const char *path, const char *name) { _cleanup_free_ char *val = NULL; int r; assert(path); assert(name); r = cg_get_xattr_malloc(controller, path, name, &val); if (r < 0) return r; return parse_boolean(val); } int cg_remove_xattr(const char *controller, const char *path, const char *name) { _cleanup_free_ char *fs = NULL; int r; assert(path); assert(name); r = cg_get_path(controller, path, NULL, &fs); if (r < 0) return r; return RET_NERRNO(removexattr(fs, name)); } int cg_pid_get_path(const char *controller, pid_t pid, char **ret_path) { _cleanup_fclose_ FILE *f = NULL; const char *fs, *controller_str = NULL; /* avoid false maybe-uninitialized warning */ int unified, r; assert(pid >= 0); assert(ret_path); if (controller) { if (!cg_controller_is_valid(controller)) return -EINVAL; } else controller = SYSTEMD_CGROUP_CONTROLLER; unified = cg_unified_controller(controller); if (unified < 0) return unified; if (unified == 0) { if (streq(controller, SYSTEMD_CGROUP_CONTROLLER)) controller_str = SYSTEMD_CGROUP_CONTROLLER_LEGACY; else controller_str = controller; } fs = procfs_file_alloca(pid, "cgroup"); r = fopen_unlocked(fs, "re", &f); if (r == -ENOENT) return -ESRCH; if (r < 0) return r; for (;;) { _cleanup_free_ char *line = NULL; char *e; r = read_line(f, LONG_LINE_MAX, &line); if (r < 0) return r; if (r == 0) return -ENODATA; if (unified) { e = startswith(line, "0:"); if (!e) continue; e = strchr(e, ':'); if (!e) continue; } else { char *l; l = strchr(line, ':'); if (!l) continue; l++; e = strchr(l, ':'); if (!e) continue; *e = 0; assert(controller_str); r = string_contains_word(l, ",", controller_str); if (r < 0) return r; if (r == 0) continue; } char *path = strdup(e + 1); if (!path) return -ENOMEM; /* Truncate suffix indicating the process is a zombie */ e = endswith(path, " (deleted)"); if (e) *e = 0; *ret_path = path; return 0; } } int cg_install_release_agent(const char *controller, const char *agent) { _cleanup_free_ char *fs = NULL, *contents = NULL; const char *sc; int r; assert(agent); r = cg_unified_controller(controller); if (r < 0) return r; if (r > 0) /* doesn't apply to unified hierarchy */ return -EOPNOTSUPP; r = cg_get_path(controller, NULL, "release_agent", &fs); if (r < 0) return r; r = read_one_line_file(fs, &contents); if (r < 0) return r; sc = strstrip(contents); if (isempty(sc)) { r = write_string_file(fs, agent, WRITE_STRING_FILE_DISABLE_BUFFER); if (r < 0) return r; } else if (!path_equal(sc, agent)) return -EEXIST; fs = mfree(fs); r = cg_get_path(controller, NULL, "notify_on_release", &fs); if (r < 0) return r; contents = mfree(contents); r = read_one_line_file(fs, &contents); if (r < 0) return r; sc = strstrip(contents); if (streq(sc, "0")) { r = write_string_file(fs, "1", WRITE_STRING_FILE_DISABLE_BUFFER); if (r < 0) return r; return 1; } if (!streq(sc, "1")) return -EIO; return 0; } int cg_uninstall_release_agent(const char *controller) { _cleanup_free_ char *fs = NULL; int r; r = cg_unified_controller(controller); if (r < 0) return r; if (r > 0) /* Doesn't apply to unified hierarchy */ return -EOPNOTSUPP; r = cg_get_path(controller, NULL, "notify_on_release", &fs); if (r < 0) return r; r = write_string_file(fs, "0", WRITE_STRING_FILE_DISABLE_BUFFER); if (r < 0) return r; fs = mfree(fs); r = cg_get_path(controller, NULL, "release_agent", &fs); if (r < 0) return r; r = write_string_file(fs, "", WRITE_STRING_FILE_DISABLE_BUFFER); if (r < 0) return r; return 0; } int cg_is_empty(const char *controller, const char *path) { _cleanup_fclose_ FILE *f = NULL; pid_t pid; int r; assert(path); r = cg_enumerate_processes(controller, path, &f); if (r == -ENOENT) return true; if (r < 0) return r; r = cg_read_pid(f, &pid); if (r < 0) return r; return r == 0; } int cg_is_empty_recursive(const char *controller, const char *path) { int r; assert(path); /* The root cgroup is always populated */ if (controller && empty_or_root(path)) return false; r = cg_unified_controller(controller); if (r < 0) return r; if (r > 0) { _cleanup_free_ char *t = NULL; /* On the unified hierarchy we can check empty state * via the "populated" attribute of "cgroup.events". */ r = cg_read_event(controller, path, "populated", &t); if (r == -ENOENT) return true; if (r < 0) return r; return streq(t, "0"); } else { _cleanup_closedir_ DIR *d = NULL; char *fn; r = cg_is_empty(controller, path); if (r <= 0) return r; r = cg_enumerate_subgroups(controller, path, &d); if (r == -ENOENT) return true; if (r < 0) return r; while ((r = cg_read_subgroup(d, &fn)) > 0) { _cleanup_free_ char *p = NULL; p = path_join(path, fn); free(fn); if (!p) return -ENOMEM; r = cg_is_empty_recursive(controller, p); if (r <= 0) return r; } if (r < 0) return r; return true; } } int cg_split_spec(const char *spec, char **ret_controller, char **ret_path) { _cleanup_free_ char *controller = NULL, *path = NULL; assert(spec); if (*spec == '/') { if (!path_is_normalized(spec)) return -EINVAL; if (ret_path) { path = strdup(spec); if (!path) return -ENOMEM; path_simplify(path); } } else { const char *e; e = strchr(spec, ':'); if (e) { controller = strndup(spec, e-spec); if (!controller) return -ENOMEM; if (!cg_controller_is_valid(controller)) return -EINVAL; if (!isempty(e + 1)) { path = strdup(e+1); if (!path) return -ENOMEM; if (!path_is_normalized(path) || !path_is_absolute(path)) return -EINVAL; path_simplify(path); } } else { if (!cg_controller_is_valid(spec)) return -EINVAL; if (ret_controller) { controller = strdup(spec); if (!controller) return -ENOMEM; } } } if (ret_controller) *ret_controller = TAKE_PTR(controller); if (ret_path) *ret_path = TAKE_PTR(path); return 0; } int cg_mangle_path(const char *path, char **result) { _cleanup_free_ char *c = NULL, *p = NULL; char *t; int r; assert(path); assert(result); /* First, check if it already is a filesystem path */ if (path_startswith(path, "/sys/fs/cgroup")) { t = strdup(path); if (!t) return -ENOMEM; *result = path_simplify(t); return 0; } /* Otherwise, treat it as cg spec */ r = cg_split_spec(path, &c, &p); if (r < 0) return r; return cg_get_path(c ?: SYSTEMD_CGROUP_CONTROLLER, p ?: "/", NULL, result); } int cg_get_root_path(char **path) { char *p, *e; int r; assert(path); r = cg_pid_get_path(SYSTEMD_CGROUP_CONTROLLER, 1, &p); if (r < 0) return r; e = endswith(p, "/" SPECIAL_INIT_SCOPE); if (!e) e = endswith(p, "/" SPECIAL_SYSTEM_SLICE); /* legacy */ if (!e) e = endswith(p, "/system"); /* even more legacy */ if (e) *e = 0; *path = p; return 0; } int cg_shift_path(const char *cgroup, const char *root, const char **shifted) { _cleanup_free_ char *rt = NULL; char *p; int r; assert(cgroup); assert(shifted); if (!root) { /* If the root was specified let's use that, otherwise * let's determine it from PID 1 */ r = cg_get_root_path(&rt); if (r < 0) return r; root = rt; } p = path_startswith(cgroup, root); if (p && p > cgroup) *shifted = p - 1; else *shifted = cgroup; return 0; } int cg_pid_get_path_shifted(pid_t pid, const char *root, char **cgroup) { _cleanup_free_ char *raw = NULL; const char *c; int r; assert(pid >= 0); assert(cgroup); r = cg_pid_get_path(SYSTEMD_CGROUP_CONTROLLER, pid, &raw); if (r < 0) return r; r = cg_shift_path(raw, root, &c); if (r < 0) return r; if (c == raw) *cgroup = TAKE_PTR(raw); else { char *n; n = strdup(c); if (!n) return -ENOMEM; *cgroup = n; } return 0; } int cg_path_decode_unit(const char *cgroup, char **unit) { char *c, *s; size_t n; assert(cgroup); assert(unit); n = strcspn(cgroup, "/"); if (n < 3) return -ENXIO; c = strndupa_safe(cgroup, n); c = cg_unescape(c); if (!unit_name_is_valid(c, UNIT_NAME_PLAIN|UNIT_NAME_INSTANCE)) return -ENXIO; s = strdup(c); if (!s) return -ENOMEM; *unit = s; return 0; } static bool valid_slice_name(const char *p, size_t n) { if (!p) return false; if (n < STRLEN("x.slice")) return false; if (memcmp(p + n - 6, ".slice", 6) == 0) { char buf[n+1], *c; memcpy(buf, p, n); buf[n] = 0; c = cg_unescape(buf); return unit_name_is_valid(c, UNIT_NAME_PLAIN); } return false; } static const char *skip_slices(const char *p) { assert(p); /* Skips over all slice assignments */ for (;;) { size_t n; p += strspn(p, "/"); n = strcspn(p, "/"); if (!valid_slice_name(p, n)) return p; p += n; } } int cg_path_get_unit(const char *path, char **ret) { _cleanup_free_ char *unit = NULL; const char *e; int r; assert(path); assert(ret); e = skip_slices(path); r = cg_path_decode_unit(e, &unit); if (r < 0) return r; /* We skipped over the slices, don't accept any now */ if (endswith(unit, ".slice")) return -ENXIO; *ret = TAKE_PTR(unit); return 0; } int cg_path_get_unit_path(const char *path, char **ret) { _cleanup_free_ char *path_copy = NULL; char *unit_name; assert(path); assert(ret); path_copy = strdup(path); if (!path_copy) return -ENOMEM; unit_name = (char *)skip_slices(path_copy); unit_name[strcspn(unit_name, "/")] = 0; if (!unit_name_is_valid(cg_unescape(unit_name), UNIT_NAME_PLAIN|UNIT_NAME_INSTANCE)) return -ENXIO; *ret = TAKE_PTR(path_copy); return 0; } int cg_pid_get_unit(pid_t pid, char **unit) { _cleanup_free_ char *cgroup = NULL; int r; assert(unit); r = cg_pid_get_path_shifted(pid, NULL, &cgroup); if (r < 0) return r; return cg_path_get_unit(cgroup, unit); } /** * Skip session-*.scope, but require it to be there. */ static const char *skip_session(const char *p) { size_t n; if (isempty(p)) return NULL; p += strspn(p, "/"); n = strcspn(p, "/"); if (n < STRLEN("session-x.scope")) return NULL; if (memcmp(p, "session-", 8) == 0 && memcmp(p + n - 6, ".scope", 6) == 0) { char buf[n - 8 - 6 + 1]; memcpy(buf, p + 8, n - 8 - 6); buf[n - 8 - 6] = 0; /* Note that session scopes never need unescaping, * since they cannot conflict with the kernel's own * names, hence we don't need to call cg_unescape() * here. */ if (!session_id_valid(buf)) return NULL; p += n; p += strspn(p, "/"); return p; } return NULL; } /** * Skip user@*.service, but require it to be there. */ static const char *skip_user_manager(const char *p) { size_t n; if (isempty(p)) return NULL; p += strspn(p, "/"); n = strcspn(p, "/"); if (n < STRLEN("user@x.service")) return NULL; if (memcmp(p, "user@", 5) == 0 && memcmp(p + n - 8, ".service", 8) == 0) { char buf[n - 5 - 8 + 1]; memcpy(buf, p + 5, n - 5 - 8); buf[n - 5 - 8] = 0; /* Note that user manager services never need unescaping, * since they cannot conflict with the kernel's own * names, hence we don't need to call cg_unescape() * here. */ if (parse_uid(buf, NULL) < 0) return NULL; p += n; p += strspn(p, "/"); return p; } return NULL; } static const char *skip_user_prefix(const char *path) { const char *e, *t; assert(path); /* Skip slices, if there are any */ e = skip_slices(path); /* Skip the user manager, if it's in the path now... */ t = skip_user_manager(e); if (t) return t; /* Alternatively skip the user session if it is in the path... */ return skip_session(e); } int cg_path_get_user_unit(const char *path, char **ret) { const char *t; assert(path); assert(ret); t = skip_user_prefix(path); if (!t) return -ENXIO; /* And from here on it looks pretty much the same as for a system unit, hence let's use the same * parser. */ return cg_path_get_unit(t, ret); } int cg_pid_get_user_unit(pid_t pid, char **unit) { _cleanup_free_ char *cgroup = NULL; int r; assert(unit); r = cg_pid_get_path_shifted(pid, NULL, &cgroup); if (r < 0) return r; return cg_path_get_user_unit(cgroup, unit); } int cg_path_get_machine_name(const char *path, char **machine) { _cleanup_free_ char *u = NULL; const char *sl; int r; r = cg_path_get_unit(path, &u); if (r < 0) return r; sl = strjoina("/run/systemd/machines/unit:", u); return readlink_malloc(sl, machine); } int cg_pid_get_machine_name(pid_t pid, char **machine) { _cleanup_free_ char *cgroup = NULL; int r; assert(machine); r = cg_pid_get_path_shifted(pid, NULL, &cgroup); if (r < 0) return r; return cg_path_get_machine_name(cgroup, machine); } int cg_path_get_cgroupid(const char *path, uint64_t *ret) { cg_file_handle fh = CG_FILE_HANDLE_INIT; int mnt_id = -1; assert(path); assert(ret); /* This is cgroupfs so we know the size of the handle, thus no need to loop around like * name_to_handle_at_loop() does in mountpoint-util.c */ if (name_to_handle_at(AT_FDCWD, path, &fh.file_handle, &mnt_id, 0) < 0) return -errno; *ret = CG_FILE_HANDLE_CGROUPID(fh); return 0; } int cg_path_get_session(const char *path, char **session) { _cleanup_free_ char *unit = NULL; char *start, *end; int r; assert(path); r = cg_path_get_unit(path, &unit); if (r < 0) return r; start = startswith(unit, "session-"); if (!start) return -ENXIO; end = endswith(start, ".scope"); if (!end) return -ENXIO; *end = 0; if (!session_id_valid(start)) return -ENXIO; if (session) { char *rr; rr = strdup(start); if (!rr) return -ENOMEM; *session = rr; } return 0; } int cg_pid_get_session(pid_t pid, char **session) { _cleanup_free_ char *cgroup = NULL; int r; r = cg_pid_get_path_shifted(pid, NULL, &cgroup); if (r < 0) return r; return cg_path_get_session(cgroup, session); } int cg_path_get_owner_uid(const char *path, uid_t *uid) { _cleanup_free_ char *slice = NULL; char *start, *end; int r; assert(path); r = cg_path_get_slice(path, &slice); if (r < 0) return r; start = startswith(slice, "user-"); if (!start) return -ENXIO; end = endswith(start, ".slice"); if (!end) return -ENXIO; *end = 0; if (parse_uid(start, uid) < 0) return -ENXIO; return 0; } int cg_pid_get_owner_uid(pid_t pid, uid_t *uid) { _cleanup_free_ char *cgroup = NULL; int r; r = cg_pid_get_path_shifted(pid, NULL, &cgroup); if (r < 0) return r; return cg_path_get_owner_uid(cgroup, uid); } int cg_path_get_slice(const char *p, char **slice) { const char *e = NULL; assert(p); assert(slice); /* Finds the right-most slice unit from the beginning, but * stops before we come to the first non-slice unit. */ for (;;) { size_t n; p += strspn(p, "/"); n = strcspn(p, "/"); if (!valid_slice_name(p, n)) { if (!e) { char *s; s = strdup(SPECIAL_ROOT_SLICE); if (!s) return -ENOMEM; *slice = s; return 0; } return cg_path_decode_unit(e, slice); } e = p; p += n; } } int cg_pid_get_slice(pid_t pid, char **slice) { _cleanup_free_ char *cgroup = NULL; int r; assert(slice); r = cg_pid_get_path_shifted(pid, NULL, &cgroup); if (r < 0) return r; return cg_path_get_slice(cgroup, slice); } int cg_path_get_user_slice(const char *p, char **slice) { const char *t; assert(p); assert(slice); t = skip_user_prefix(p); if (!t) return -ENXIO; /* And now it looks pretty much the same as for a system * slice, so let's just use the same parser from here on. */ return cg_path_get_slice(t, slice); } int cg_pid_get_user_slice(pid_t pid, char **slice) { _cleanup_free_ char *cgroup = NULL; int r; assert(slice); r = cg_pid_get_path_shifted(pid, NULL, &cgroup); if (r < 0) return r; return cg_path_get_user_slice(cgroup, slice); } char *cg_escape(const char *p) { bool need_prefix = false; /* This implements very minimal escaping for names to be used * as file names in the cgroup tree: any name which might * conflict with a kernel name or is prefixed with '_' is * prefixed with a '_'. That way, when reading cgroup names it * is sufficient to remove a single prefixing underscore if * there is one. */ /* The return value of this function (unlike cg_unescape()) * needs free()! */ if (IN_SET(p[0], 0, '_', '.') || STR_IN_SET(p, "notify_on_release", "release_agent", "tasks") || startswith(p, "cgroup.")) need_prefix = true; else { const char *dot; dot = strrchr(p, '.'); if (dot) { CGroupController c; size_t l = dot - p; for (c = 0; c < _CGROUP_CONTROLLER_MAX; c++) { const char *n; n = cgroup_controller_to_string(c); if (l != strlen(n)) continue; if (memcmp(p, n, l) != 0) continue; need_prefix = true; break; } } } if (need_prefix) return strjoin("_", p); return strdup(p); } char *cg_unescape(const char *p) { assert(p); /* The return value of this function (unlike cg_escape()) * doesn't need free()! */ if (p[0] == '_') return (char*) p+1; return (char*) p; } #define CONTROLLER_VALID \ DIGITS LETTERS \ "_" bool cg_controller_is_valid(const char *p) { const char *t, *s; if (!p) return false; if (streq(p, SYSTEMD_CGROUP_CONTROLLER)) return true; s = startswith(p, "name="); if (s) p = s; if (IN_SET(*p, 0, '_')) return false; for (t = p; *t; t++) if (!strchr(CONTROLLER_VALID, *t)) return false; if (t - p > NAME_MAX) return false; return true; } int cg_slice_to_path(const char *unit, char **ret) { _cleanup_free_ char *p = NULL, *s = NULL, *e = NULL; const char *dash; int r; assert(unit); assert(ret); if (streq(unit, SPECIAL_ROOT_SLICE)) { char *x; x = strdup(""); if (!x) return -ENOMEM; *ret = x; return 0; } if (!unit_name_is_valid(unit, UNIT_NAME_PLAIN)) return -EINVAL; if (!endswith(unit, ".slice")) return -EINVAL; r = unit_name_to_prefix(unit, &p); if (r < 0) return r; dash = strchr(p, '-'); /* Don't allow initial dashes */ if (dash == p) return -EINVAL; while (dash) { _cleanup_free_ char *escaped = NULL; char n[dash - p + sizeof(".slice")]; #if HAS_FEATURE_MEMORY_SANITIZER /* msan doesn't instrument stpncpy, so it thinks * n is later used uninitialized: * https://github.com/google/sanitizers/issues/926 */ zero(n); #endif /* Don't allow trailing or double dashes */ if (IN_SET(dash[1], 0, '-')) return -EINVAL; strcpy(stpncpy(n, p, dash - p), ".slice"); if (!unit_name_is_valid(n, UNIT_NAME_PLAIN)) return -EINVAL; escaped = cg_escape(n); if (!escaped) return -ENOMEM; if (!strextend(&s, escaped, "/")) return -ENOMEM; dash = strchr(dash+1, '-'); } e = cg_escape(unit); if (!e) return -ENOMEM; if (!strextend(&s, e)) return -ENOMEM; *ret = TAKE_PTR(s); return 0; } int cg_is_threaded(const char *controller, const char *path) { _cleanup_free_ char *fs = NULL, *contents = NULL; _cleanup_strv_free_ char **v = NULL; int r; r = cg_get_path(controller, path, "cgroup.type", &fs); if (r < 0) return r; r = read_full_virtual_file(fs, &contents, NULL); if (r == -ENOENT) return false; /* Assume no. */ if (r < 0) return r; v = strv_split(contents, NULL); if (!v) return -ENOMEM; /* If the cgroup is in the threaded mode, it contains "threaded". * If one of the parents or siblings is in the threaded mode, it may contain "invalid". */ return strv_contains(v, "threaded") || strv_contains(v, "invalid"); } int cg_set_attribute(const char *controller, const char *path, const char *attribute, const char *value) { _cleanup_free_ char *p = NULL; int r; r = cg_get_path(controller, path, attribute, &p); if (r < 0) return r; return write_string_file(p, value, WRITE_STRING_FILE_DISABLE_BUFFER); } int cg_get_attribute(const char *controller, const char *path, const char *attribute, char **ret) { _cleanup_free_ char *p = NULL; int r; r = cg_get_path(controller, path, attribute, &p); if (r < 0) return r; return read_one_line_file(p, ret); } int cg_get_attribute_as_uint64(const char *controller, const char *path, const char *attribute, uint64_t *ret) { _cleanup_free_ char *value = NULL; uint64_t v; int r; assert(ret); r = cg_get_attribute(controller, path, attribute, &value); if (r == -ENOENT) return -ENODATA; if (r < 0) return r; if (streq(value, "max")) { *ret = CGROUP_LIMIT_MAX; return 0; } r = safe_atou64(value, &v); if (r < 0) return r; *ret = v; return 0; } int cg_get_attribute_as_bool(const char *controller, const char *path, const char *attribute, bool *ret) { _cleanup_free_ char *value = NULL; int r; assert(ret); r = cg_get_attribute(controller, path, attribute, &value); if (r == -ENOENT) return -ENODATA; if (r < 0) return r; r = parse_boolean(value); if (r < 0) return r; *ret = r; return 0; } int cg_get_owner(const char *controller, const char *path, uid_t *ret_uid) { _cleanup_free_ char *f = NULL; struct stat stats; int r; assert(ret_uid); r = cg_get_path(controller, path, NULL, &f); if (r < 0) return r; r = stat(f, &stats); if (r < 0) return -errno; *ret_uid = stats.st_uid; return 0; } int cg_get_keyed_attribute_full( const char *controller, const char *path, const char *attribute, char **keys, char **ret_values, CGroupKeyMode mode) { _cleanup_free_ char *filename = NULL, *contents = NULL; const char *p; size_t n, i, n_done = 0; char **v; int r; /* Reads one or more fields of a cgroup v2 keyed attribute file. The 'keys' parameter should be an strv with * all keys to retrieve. The 'ret_values' parameter should be passed as string size with the same number of * entries as 'keys'. On success each entry will be set to the value of the matching key. * * If the attribute file doesn't exist at all returns ENOENT, if any key is not found returns ENXIO. If mode * is set to GG_KEY_MODE_GRACEFUL we ignore missing keys and return those that were parsed successfully. */ r = cg_get_path(controller, path, attribute, &filename); if (r < 0) return r; r = read_full_file(filename, &contents, NULL); if (r < 0) return r; n = strv_length(keys); if (n == 0) /* No keys to retrieve? That's easy, we are done then */ return 0; /* Let's build this up in a temporary array for now in order not to clobber the return parameter on failure */ v = newa0(char*, n); for (p = contents; *p;) { const char *w = NULL; for (i = 0; i < n; i++) if (!v[i]) { w = first_word(p, keys[i]); if (w) break; } if (w) { size_t l; l = strcspn(w, NEWLINE); v[i] = strndup(w, l); if (!v[i]) { r = -ENOMEM; goto fail; } n_done++; if (n_done >= n) goto done; p = w + l; } else p += strcspn(p, NEWLINE); p += strspn(p, NEWLINE); } if (mode & CG_KEY_MODE_GRACEFUL) goto done; r = -ENXIO; fail: for (i = 0; i < n; i++) free(v[i]); return r; done: memcpy(ret_values, v, sizeof(char*) * n); if (mode & CG_KEY_MODE_GRACEFUL) return n_done; return 0; } int cg_mask_to_string(CGroupMask mask, char **ret) { _cleanup_free_ char *s = NULL; bool space = false; CGroupController c; size_t n = 0; assert(ret); if (mask == 0) { *ret = NULL; return 0; } for (c = 0; c < _CGROUP_CONTROLLER_MAX; c++) { const char *k; size_t l; if (!FLAGS_SET(mask, CGROUP_CONTROLLER_TO_MASK(c))) continue; k = cgroup_controller_to_string(c); l = strlen(k); if (!GREEDY_REALLOC(s, n + space + l + 1)) return -ENOMEM; if (space) s[n] = ' '; memcpy(s + n + space, k, l); n += space + l; space = true; } assert(s); s[n] = 0; *ret = TAKE_PTR(s); return 0; } int cg_mask_from_string(const char *value, CGroupMask *ret) { CGroupMask m = 0; assert(ret); assert(value); for (;;) { _cleanup_free_ char *n = NULL; CGroupController v; int r; r = extract_first_word(&value, &n, NULL, 0); if (r < 0) return r; if (r == 0) break; v = cgroup_controller_from_string(n); if (v < 0) continue; m |= CGROUP_CONTROLLER_TO_MASK(v); } *ret = m; return 0; } int cg_mask_supported_subtree(const char *root, CGroupMask *ret) { CGroupMask mask; int r; /* Determines the mask of supported cgroup controllers. Only includes controllers we can make sense of and that * are actually accessible. Only covers real controllers, i.e. not the CGROUP_CONTROLLER_BPF_xyz * pseudo-controllers. */ r = cg_all_unified(); if (r < 0) return r; if (r > 0) { _cleanup_free_ char *controllers = NULL, *path = NULL; /* In the unified hierarchy we can read the supported and accessible controllers from * the top-level cgroup attribute */ r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, root, "cgroup.controllers", &path); if (r < 0) return r; r = read_one_line_file(path, &controllers); if (r < 0) return r; r = cg_mask_from_string(controllers, &mask); if (r < 0) return r; /* Mask controllers that are not supported in unified hierarchy. */ mask &= CGROUP_MASK_V2; } else { CGroupController c; /* In the legacy hierarchy, we check which hierarchies are accessible. */ mask = 0; for (c = 0; c < _CGROUP_CONTROLLER_MAX; c++) { CGroupMask bit = CGROUP_CONTROLLER_TO_MASK(c); const char *n; if (!FLAGS_SET(CGROUP_MASK_V1, bit)) continue; n = cgroup_controller_to_string(c); if (controller_is_v1_accessible(root, n) >= 0) mask |= bit; } } *ret = mask; return 0; } int cg_mask_supported(CGroupMask *ret) { _cleanup_free_ char *root = NULL; int r; r = cg_get_root_path(&root); if (r < 0) return r; return cg_mask_supported_subtree(root, ret); } int cg_kernel_controllers(Set **ret) { _cleanup_set_free_ Set *controllers = NULL; _cleanup_fclose_ FILE *f = NULL; int r; assert(ret); /* Determines the full list of kernel-known controllers. Might include controllers we don't actually support * and controllers that aren't currently accessible (because not mounted). This does not include "name=" * pseudo-controllers. */ r = fopen_unlocked("/proc/cgroups", "re", &f); if (r == -ENOENT) { *ret = NULL; return 0; } if (r < 0) return r; /* Ignore the header line */ (void) read_line(f, SIZE_MAX, NULL); for (;;) { _cleanup_free_ char *controller = NULL; int enabled = 0; errno = 0; if (fscanf(f, "%ms %*i %*i %i", &controller, &enabled) != 2) { if (feof(f)) break; if (ferror(f)) return errno_or_else(EIO); return -EBADMSG; } if (!enabled) continue; if (!cg_controller_is_valid(controller)) return -EBADMSG; r = set_ensure_consume(&controllers, &string_hash_ops_free, TAKE_PTR(controller)); if (r < 0) return r; } *ret = TAKE_PTR(controllers); return 0; } /* The hybrid mode was initially implemented in v232 and simply mounted cgroup2 on * /sys/fs/cgroup/systemd. This unfortunately broke other tools (such as docker) which expected the v1 * "name=systemd" hierarchy on /sys/fs/cgroup/systemd. From v233 and on, the hybrid mode mounts v2 on * /sys/fs/cgroup/unified and maintains "name=systemd" hierarchy on /sys/fs/cgroup/systemd for compatibility * with other tools. * * To keep live upgrade working, we detect and support v232 layout. When v232 layout is detected, to keep * cgroup v2 process management but disable the compat dual layout, we return true on * cg_unified_controller(SYSTEMD_CGROUP_CONTROLLER) and false on cg_hybrid_unified(). */ static thread_local bool unified_systemd_v232; int cg_unified_cached(bool flush) { static thread_local CGroupUnified unified_cache = CGROUP_UNIFIED_UNKNOWN; struct statfs fs; /* Checks if we support the unified hierarchy. Returns an * error when the cgroup hierarchies aren't mounted yet or we * have any other trouble determining if the unified hierarchy * is supported. */ if (flush) unified_cache = CGROUP_UNIFIED_UNKNOWN; else if (unified_cache >= CGROUP_UNIFIED_NONE) return unified_cache; if (statfs("/sys/fs/cgroup/", &fs) < 0) return log_debug_errno(errno, "statfs(\"/sys/fs/cgroup/\") failed: %m"); if (F_TYPE_EQUAL(fs.f_type, CGROUP2_SUPER_MAGIC)) { log_debug("Found cgroup2 on /sys/fs/cgroup/, full unified hierarchy"); unified_cache = CGROUP_UNIFIED_ALL; } else if (F_TYPE_EQUAL(fs.f_type, TMPFS_MAGIC)) { if (statfs("/sys/fs/cgroup/unified/", &fs) == 0 && F_TYPE_EQUAL(fs.f_type, CGROUP2_SUPER_MAGIC)) { log_debug("Found cgroup2 on /sys/fs/cgroup/unified, unified hierarchy for systemd controller"); unified_cache = CGROUP_UNIFIED_SYSTEMD; unified_systemd_v232 = false; } else { if (statfs("/sys/fs/cgroup/systemd/", &fs) < 0) { if (errno == ENOENT) { /* Some other software may have set up /sys/fs/cgroup in a configuration we do not recognize. */ log_debug_errno(errno, "Unsupported cgroupsv1 setup detected: name=systemd hierarchy not found."); return -ENOMEDIUM; } return log_debug_errno(errno, "statfs(\"/sys/fs/cgroup/systemd\" failed: %m"); } if (F_TYPE_EQUAL(fs.f_type, CGROUP2_SUPER_MAGIC)) { log_debug("Found cgroup2 on /sys/fs/cgroup/systemd, unified hierarchy for systemd controller (v232 variant)"); unified_cache = CGROUP_UNIFIED_SYSTEMD; unified_systemd_v232 = true; } else if (F_TYPE_EQUAL(fs.f_type, CGROUP_SUPER_MAGIC)) { log_debug("Found cgroup on /sys/fs/cgroup/systemd, legacy hierarchy"); unified_cache = CGROUP_UNIFIED_NONE; } else { log_debug("Unexpected filesystem type %llx mounted on /sys/fs/cgroup/systemd, assuming legacy hierarchy", (unsigned long long) fs.f_type); unified_cache = CGROUP_UNIFIED_NONE; } } } else if (F_TYPE_EQUAL(fs.f_type, SYSFS_MAGIC)) { return log_debug_errno(SYNTHETIC_ERRNO(ENOMEDIUM), "No filesystem is currently mounted on /sys/fs/cgroup."); } else return log_debug_errno(SYNTHETIC_ERRNO(ENOMEDIUM), "Unknown filesystem type %llx mounted on /sys/fs/cgroup.", (unsigned long long)fs.f_type); return unified_cache; } int cg_unified_controller(const char *controller) { int r; r = cg_unified_cached(false); if (r < 0) return r; if (r == CGROUP_UNIFIED_NONE) return false; if (r >= CGROUP_UNIFIED_ALL) return true; return streq_ptr(controller, SYSTEMD_CGROUP_CONTROLLER); } int cg_all_unified(void) { int r; r = cg_unified_cached(false); if (r < 0) return r; return r >= CGROUP_UNIFIED_ALL; } int cg_hybrid_unified(void) { int r; r = cg_unified_cached(false); if (r < 0) return r; return r == CGROUP_UNIFIED_SYSTEMD && !unified_systemd_v232; } const uint64_t cgroup_io_limit_defaults[_CGROUP_IO_LIMIT_TYPE_MAX] = { [CGROUP_IO_RBPS_MAX] = CGROUP_LIMIT_MAX, [CGROUP_IO_WBPS_MAX] = CGROUP_LIMIT_MAX, [CGROUP_IO_RIOPS_MAX] = CGROUP_LIMIT_MAX, [CGROUP_IO_WIOPS_MAX] = CGROUP_LIMIT_MAX, }; static const char* const cgroup_io_limit_type_table[_CGROUP_IO_LIMIT_TYPE_MAX] = { [CGROUP_IO_RBPS_MAX] = "IOReadBandwidthMax", [CGROUP_IO_WBPS_MAX] = "IOWriteBandwidthMax", [CGROUP_IO_RIOPS_MAX] = "IOReadIOPSMax", [CGROUP_IO_WIOPS_MAX] = "IOWriteIOPSMax", }; DEFINE_STRING_TABLE_LOOKUP(cgroup_io_limit_type, CGroupIOLimitType); bool is_cgroup_fs(const struct statfs *s) { return is_fs_type(s, CGROUP_SUPER_MAGIC) || is_fs_type(s, CGROUP2_SUPER_MAGIC); } bool fd_is_cgroup_fs(int fd) { struct statfs s; if (fstatfs(fd, &s) < 0) return -errno; return is_cgroup_fs(&s); } static const char *const cgroup_controller_table[_CGROUP_CONTROLLER_MAX] = { [CGROUP_CONTROLLER_CPU] = "cpu", [CGROUP_CONTROLLER_CPUACCT] = "cpuacct", [CGROUP_CONTROLLER_CPUSET] = "cpuset", [CGROUP_CONTROLLER_IO] = "io", [CGROUP_CONTROLLER_BLKIO] = "blkio", [CGROUP_CONTROLLER_MEMORY] = "memory", [CGROUP_CONTROLLER_DEVICES] = "devices", [CGROUP_CONTROLLER_PIDS] = "pids", [CGROUP_CONTROLLER_BPF_FIREWALL] = "bpf-firewall", [CGROUP_CONTROLLER_BPF_DEVICES] = "bpf-devices", [CGROUP_CONTROLLER_BPF_FOREIGN] = "bpf-foreign", [CGROUP_CONTROLLER_BPF_SOCKET_BIND] = "bpf-socket-bind", [CGROUP_CONTROLLER_BPF_RESTRICT_NETWORK_INTERFACES] = "bpf-restrict-network-interfaces", }; DEFINE_STRING_TABLE_LOOKUP(cgroup_controller, CGroupController); CGroupMask get_cpu_accounting_mask(void) { static CGroupMask needed_mask = (CGroupMask) -1; /* On kernel ≥4.15 with unified hierarchy, cpu.stat's usage_usec is * provided externally from the CPU controller, which means we don't * need to enable the CPU controller just to get metrics. This is good, * because enabling the CPU controller comes at a minor performance * hit, especially when it's propagated deep into large hierarchies. * There's also no separate CPU accounting controller available within * a unified hierarchy. * * This combination of factors results in the desired cgroup mask to * enable for CPU accounting varying as follows: * * ╔═════════════════════╤═════════════════════╗ * ║ Linux ≥4.15 │ Linux <4.15 ║ * ╔═══════════════╬═════════════════════╪═════════════════════╣ * ║ Unified ║ nothing │ CGROUP_MASK_CPU ║ * ╟───────────────╫─────────────────────┼─────────────────────╢ * ║ Hybrid/Legacy ║ CGROUP_MASK_CPUACCT │ CGROUP_MASK_CPUACCT ║ * ╚═══════════════╩═════════════════════╧═════════════════════╝ * * We check kernel version here instead of manually checking whether * cpu.stat is present for every cgroup, as that check in itself would * already be fairly expensive. * * Kernels where this patch has been backported will therefore have the * CPU controller enabled unnecessarily. This is more expensive than * necessary, but harmless. ☺️ */ if (needed_mask == (CGroupMask) -1) { if (cg_all_unified()) { struct utsname u; assert_se(uname(&u) >= 0); if (strverscmp_improved(u.release, "4.15") < 0) needed_mask = CGROUP_MASK_CPU; else needed_mask = 0; } else needed_mask = CGROUP_MASK_CPUACCT; } return needed_mask; } bool cpu_accounting_is_cheap(void) { return get_cpu_accounting_mask() == 0; } static const char* const managed_oom_mode_table[_MANAGED_OOM_MODE_MAX] = { [MANAGED_OOM_AUTO] = "auto", [MANAGED_OOM_KILL] = "kill", }; DEFINE_STRING_TABLE_LOOKUP(managed_oom_mode, ManagedOOMMode); static const char* const managed_oom_preference_table[_MANAGED_OOM_PREFERENCE_MAX] = { [MANAGED_OOM_PREFERENCE_NONE] = "none", [MANAGED_OOM_PREFERENCE_AVOID] = "avoid", [MANAGED_OOM_PREFERENCE_OMIT] = "omit", }; DEFINE_STRING_TABLE_LOOKUP(managed_oom_preference, ManagedOOMPreference);