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-rw-r--r--src/basic/cgroup-util.c2434
1 files changed, 2434 insertions, 0 deletions
diff --git a/src/basic/cgroup-util.c b/src/basic/cgroup-util.c
new file mode 100644
index 0000000..18b16ec
--- /dev/null
+++ b/src/basic/cgroup-util.c
@@ -0,0 +1,2434 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <limits.h>
+#include <signal.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/utsname.h>
+#include <sys/xattr.h>
+#include <unistd.h>
+
+#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 **ret, const char *item) {
+ _cleanup_free_ char *fs = NULL;
+ FILE *f;
+ int r;
+
+ assert(ret);
+
+ r = cg_get_path(controller, path, item, &fs);
+ if (r < 0)
+ return r;
+
+ f = fopen(fs, "re");
+ if (!f)
+ return -errno;
+
+ *ret = f;
+ return 0;
+}
+
+int cg_enumerate_processes(const char *controller, const char *path, FILE **ret) {
+ return cg_enumerate_items(controller, path, ret, "cgroup.procs");
+}
+
+int cg_read_pid(FILE *f, pid_t *ret) {
+ unsigned long ul;
+
+ /* Note that the cgroup.procs might contain duplicates! See cgroups.txt for details. */
+
+ assert(f);
+ assert(ret);
+
+ errno = 0;
+ if (fscanf(f, "%lu", &ul) != 1) {
+
+ if (feof(f)) {
+ *ret = 0;
+ return 0;
+ }
+
+ return errno_or_else(EIO);
+ }
+
+ if (ul <= 0)
+ return -EIO;
+ if (ul > PID_T_MAX)
+ return -EIO;
+
+ *ret = (pid_t) ul;
+ return 1;
+}
+
+int cg_read_pidref(FILE *f, PidRef *ret) {
+ int r;
+
+ assert(f);
+ assert(ret);
+
+ for (;;) {
+ pid_t pid;
+
+ r = cg_read_pid(f, &pid);
+ if (r < 0)
+ return r;
+ if (r == 0) {
+ *ret = PIDREF_NULL;
+ return 0;
+ }
+
+ r = pidref_set_pid(ret, pid);
+ if (r >= 0)
+ return 1;
+ if (r != -ESRCH)
+ return r;
+
+ /* ESRCH → gone by now? just skip over it, read the next */
+ }
+}
+
+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 **ret) {
+ _cleanup_free_ char *fs = NULL;
+ DIR *d;
+ int r;
+
+ assert(ret);
+
+ /* This is not recursive! */
+
+ r = cg_get_path(controller, path, NULL, &fs);
+ if (r < 0)
+ return r;
+
+ d = opendir(fs);
+ if (!d)
+ return -errno;
+
+ *ret = d;
+ return 0;
+}
+
+int cg_read_subgroup(DIR *d, char **ret) {
+ assert(d);
+ assert(ret);
+
+ 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;
+
+ *ret = b;
+ return 1;
+ }
+
+ *ret = NULL;
+ 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 *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;
+
+ 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;
+ }
+
+ do {
+ _cleanup_fclose_ FILE *f = NULL;
+ done = true;
+
+ r = cg_enumerate_items(SYSTEMD_CGROUP_CONTROLLER, path, &f, item);
+ if (r == -ENOENT)
+ break;
+ if (r < 0)
+ return RET_GATHER(ret, r);
+
+ for (;;) {
+ _cleanup_(pidref_done) PidRef pidref = PIDREF_NULL;
+
+ r = cg_read_pidref(f, &pidref);
+ if (r < 0)
+ return RET_GATHER(ret, r);
+ if (r == 0)
+ break;
+
+ if ((flags & CGROUP_IGNORE_SELF) && pidref_is_self(&pidref))
+ continue;
+
+ if (set_get(s, PID_TO_PTR(pidref.pid)) == PID_TO_PTR(pidref.pid))
+ continue;
+
+ if (log_kill)
+ ret_log_kill = log_kill(&pidref, sig, userdata);
+
+ /* If we haven't killed this process yet, kill it */
+ r = pidref_kill(&pidref, sig);
+ if (r < 0 && r != -ESRCH)
+ RET_GATHER(ret, r);
+ if (r >= 0) {
+ if (flags & CGROUP_SIGCONT)
+ (void) pidref_kill(&pidref, SIGCONT);
+
+ if (ret == 0) {
+ if (log_kill)
+ ret = ret_log_kill;
+ else
+ ret = 1;
+ }
+ }
+
+ done = false;
+
+ r = set_put(s, PID_TO_PTR(pidref.pid));
+ if (r < 0)
+ return RET_GATHER(ret, r);
+ }
+
+ /* 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 *path,
+ int sig,
+ CGroupFlags flags,
+ Set *s,
+ cg_kill_log_func_t log_kill,
+ void *userdata) {
+
+ int r, ret;
+
+ r = cg_kill_items(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(SYSTEMD_CGROUP_CONTROLLER);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return ret;
+
+ r = cg_kill_items(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 *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(). */
+
+ _cleanup_free_ char *killfile = NULL;
+ int r;
+
+ assert(path);
+
+ if (!cg_kill_supported())
+ return -EOPNOTSUPP;
+
+ r = cg_get_path(SYSTEMD_CGROUP_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 *path,
+ int sig,
+ CGroupFlags flags,
+ Set *s,
+ cg_kill_log_func_t log_kill,
+ void *userdata) {
+
+ int r, ret;
+
+ 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(path);
+ else {
+ _cleanup_set_free_ Set *allocated_set = NULL;
+ _cleanup_closedir_ DIR *d = NULL;
+
+ if (!s) {
+ s = allocated_set = set_new(NULL);
+ if (!s)
+ return -ENOMEM;
+ }
+
+ ret = cg_kill(path, sig, flags, s, log_kill, userdata);
+
+ r = cg_enumerate_subgroups(SYSTEMD_CGROUP_CONTROLLER, path, &d);
+ if (r < 0) {
+ if (r != -ENOENT)
+ RET_GATHER(ret, r);
+
+ return ret;
+ }
+
+ for (;;) {
+ _cleanup_free_ char *fn = NULL, *p = NULL;
+
+ r = cg_read_subgroup(d, &fn);
+ if (r < 0) {
+ RET_GATHER(ret, r);
+ break;
+ }
+ if (r == 0)
+ break;
+
+ p = path_join(empty_to_root(path), fn);
+ if (!p)
+ return -ENOMEM;
+
+ r = cg_kill_recursive(p, sig, flags, s, log_kill, userdata);
+ if (r != 0 && ret >= 0)
+ ret = r;
+ }
+ }
+
+ if (FLAGS_SET(flags, CGROUP_REMOVE)) {
+ r = cg_rmdir(SYSTEMD_CGROUP_CONTROLLER, path);
+ if (!IN_SET(r, -ENOENT, -EBUSY))
+ RET_GATHER(ret, 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 **ret) {
+ int r;
+
+ assert(controller);
+ assert(ret);
+
+ 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, ret);
+}
+
+int cg_set_xattr(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(SYSTEMD_CGROUP_CONTROLLER, path, NULL, &fs);
+ if (r < 0)
+ return r;
+
+ return RET_NERRNO(setxattr(fs, name, value, size, flags));
+}
+
+int cg_get_xattr(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(SYSTEMD_CGROUP_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 *path, const char *name, char **ret) {
+ _cleanup_free_ char *fs = NULL;
+ int r;
+
+ assert(path);
+ assert(name);
+
+ r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, path, NULL, &fs);
+ if (r < 0)
+ return r;
+
+ return lgetxattr_malloc(fs, name, ret);
+}
+
+int cg_get_xattr_bool(const char *path, const char *name) {
+ _cleanup_free_ char *fs = NULL;
+ int r;
+
+ assert(path);
+ assert(name);
+
+ r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, path, NULL, &fs);
+ if (r < 0)
+ return r;
+
+ return getxattr_at_bool(AT_FDCWD, fs, name, /* flags= */ 0);
+}
+
+int cg_remove_xattr(const char *path, const char *name) {
+ _cleanup_free_ char *fs = NULL;
+ int r;
+
+ assert(path);
+ assert(name);
+
+ r = cg_get_path(SYSTEMD_CGROUP_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_pidref_get_path(const char *controller, const PidRef *pidref, char **ret_path) {
+ _cleanup_free_ char *path = NULL;
+ int r;
+
+ assert(ret_path);
+
+ if (!pidref_is_set(pidref))
+ return -ESRCH;
+
+ r = cg_pid_get_path(controller, pidref->pid, &path);
+ if (r < 0)
+ return r;
+
+ /* Before we return the path, make sure the procfs entry for this pid still matches the pidref */
+ r = pidref_verify(pidref);
+ if (r < 0)
+ return r;
+
+ *ret_path = TAKE_PTR(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;
+ int r;
+
+ assert(spec);
+
+ if (*spec == '/') {
+ if (!path_is_normalized(spec))
+ return -EINVAL;
+
+ if (ret_path) {
+ r = path_simplify_alloc(spec, &path);
+ if (r < 0)
+ return r;
+ }
+
+ } 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 **ret) {
+ _cleanup_free_ char *c = NULL, *p = NULL;
+ int r;
+
+ assert(path);
+ assert(ret);
+
+ /* First, check if it already is a filesystem path */
+ if (path_startswith(path, "/sys/fs/cgroup"))
+ return path_simplify_alloc(path, ret);
+
+ /* 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, ret);
+}
+
+int cg_get_root_path(char **ret_path) {
+ char *p, *e;
+ int r;
+
+ assert(ret_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;
+
+ *ret_path = p;
+ return 0;
+}
+
+int cg_shift_path(const char *cgroup, const char *root, const char **ret_shifted) {
+ _cleanup_free_ char *rt = NULL;
+ char *p;
+ int r;
+
+ assert(cgroup);
+ assert(ret_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)
+ *ret_shifted = p - 1;
+ else
+ *ret_shifted = cgroup;
+
+ return 0;
+}
+
+int cg_pid_get_path_shifted(pid_t pid, const char *root, char **ret_cgroup) {
+ _cleanup_free_ char *raw = NULL;
+ const char *c;
+ int r;
+
+ assert(pid >= 0);
+ assert(ret_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)
+ *ret_cgroup = TAKE_PTR(raw);
+ else {
+ char *n;
+
+ n = strdup(c);
+ if (!n)
+ return -ENOMEM;
+
+ *ret_cgroup = n;
+ }
+
+ return 0;
+}
+
+int cg_path_decode_unit(const char *cgroup, char **ret_unit) {
+ char *c, *s;
+ size_t n;
+
+ assert(cgroup);
+ assert(ret_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;
+
+ *ret_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 **ret_unit) {
+ _cleanup_free_ char *cgroup = NULL;
+ int r;
+
+ assert(ret_unit);
+
+ r = cg_pid_get_path_shifted(pid, NULL, &cgroup);
+ if (r < 0)
+ return r;
+
+ return cg_path_get_unit(cgroup, ret_unit);
+}
+
+int cg_pidref_get_unit(const PidRef *pidref, char **ret) {
+ _cleanup_free_ char *unit = NULL;
+ int r;
+
+ assert(ret);
+
+ if (!pidref_is_set(pidref))
+ return -ESRCH;
+
+ r = cg_pid_get_unit(pidref->pid, &unit);
+ if (r < 0)
+ return r;
+
+ r = pidref_verify(pidref);
+ if (r < 0)
+ return r;
+
+ *ret = TAKE_PTR(unit);
+ return 0;
+}
+
+/**
+ * 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 **ret_unit) {
+ _cleanup_free_ char *cgroup = NULL;
+ int r;
+
+ assert(ret_unit);
+
+ r = cg_pid_get_path_shifted(pid, NULL, &cgroup);
+ if (r < 0)
+ return r;
+
+ return cg_path_get_user_unit(cgroup, ret_unit);
+}
+
+int cg_path_get_machine_name(const char *path, char **ret_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, ret_machine);
+}
+
+int cg_pid_get_machine_name(pid_t pid, char **ret_machine) {
+ _cleanup_free_ char *cgroup = NULL;
+ int r;
+
+ assert(ret_machine);
+
+ r = cg_pid_get_path_shifted(pid, NULL, &cgroup);
+ if (r < 0)
+ return r;
+
+ return cg_path_get_machine_name(cgroup, ret_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 **ret_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 (ret_session) {
+ char *rr;
+
+ rr = strdup(start);
+ if (!rr)
+ return -ENOMEM;
+
+ *ret_session = rr;
+ }
+
+ return 0;
+}
+
+int cg_pid_get_session(pid_t pid, char **ret_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, ret_session);
+}
+
+int cg_path_get_owner_uid(const char *path, uid_t *ret_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, ret_uid) < 0)
+ return -ENXIO;
+
+ return 0;
+}
+
+int cg_pid_get_owner_uid(pid_t pid, uid_t *ret_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, ret_uid);
+}
+
+int cg_path_get_slice(const char *p, char **ret_slice) {
+ const char *e = NULL;
+
+ assert(p);
+ assert(ret_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;
+
+ *ret_slice = s;
+ return 0;
+ }
+
+ return cg_path_decode_unit(e, ret_slice);
+ }
+
+ e = p;
+ p += n;
+ }
+}
+
+int cg_pid_get_slice(pid_t pid, char **ret_slice) {
+ _cleanup_free_ char *cgroup = NULL;
+ int r;
+
+ assert(ret_slice);
+
+ r = cg_pid_get_path_shifted(pid, NULL, &cgroup);
+ if (r < 0)
+ return r;
+
+ return cg_path_get_slice(cgroup, ret_slice);
+}
+
+int cg_path_get_user_slice(const char *p, char **ret_slice) {
+ const char *t;
+ assert(p);
+ assert(ret_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, ret_slice);
+}
+
+int cg_pid_get_user_slice(pid_t pid, char **ret_slice) {
+ _cleanup_free_ char *cgroup = NULL;
+ int r;
+
+ assert(ret_slice);
+
+ r = cg_pid_get_path_shifted(pid, NULL, &cgroup);
+ if (r < 0)
+ return r;
+
+ return cg_path_get_user_slice(cgroup, ret_slice);
+}
+
+bool cg_needs_escape(const char *p) {
+
+ /* Checks if the specified path is a valid cgroup name by our rules, or if it must be escaped. Note
+ * that we consider escaped cgroup names invalid here, as they need to be escaped a second time if
+ * they shall be used. Also note that various names cannot be made valid by escaping even if we
+ * return true here (because too long, or contain the forbidden character "/"). */
+
+ if (!filename_is_valid(p))
+ return true;
+
+ if (IN_SET(p[0], '_', '.'))
+ return true;
+
+ if (STR_IN_SET(p, "notify_on_release", "release_agent", "tasks"))
+ return true;
+
+ if (startswith(p, "cgroup."))
+ return true;
+
+ for (CGroupController c = 0; c < _CGROUP_CONTROLLER_MAX; c++) {
+ const char *q;
+
+ q = startswith(p, cgroup_controller_to_string(c));
+ if (!q)
+ continue;
+
+ if (q[0] == '.')
+ return true;
+ }
+
+ return false;
+}
+
+int cg_escape(const char *p, char **ret) {
+ _cleanup_free_ char *n = NULL;
+
+ /* 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 (cg_needs_escape(p)) {
+ n = strjoin("_", p);
+ if (!n)
+ return -ENOMEM;
+
+ if (!filename_is_valid(n)) /* became invalid due to the prefixing? Or contained things like a slash that cannot be fixed by prefixing? */
+ return -EINVAL;
+ } else {
+ n = strdup(p);
+ if (!n)
+ return -ENOMEM;
+ }
+
+ *ret = TAKE_PTR(n);
+ return 0;
+}
+
+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;
+
+ r = cg_escape(n, &escaped);
+ if (r < 0)
+ return r;
+
+ if (!strextend(&s, escaped, "/"))
+ return -ENOMEM;
+
+ dash = strchr(dash+1, '-');
+ }
+
+ r = cg_escape(unit, &e);
+ if (r < 0)
+ return r;
+
+ if (!strextend(&s, e))
+ return -ENOMEM;
+
+ *ret = TAKE_PTR(s);
+ return 0;
+}
+
+int cg_is_threaded(const char *path) {
+ _cleanup_free_ char *fs = NULL, *contents = NULL;
+ _cleanup_strv_free_ char **v = NULL;
+ int r;
+
+ r = cg_get_path(SYSTEMD_CGROUP_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 *path, uid_t *ret_uid) {
+ _cleanup_free_ char *f = NULL;
+ struct stat stats;
+ int r;
+
+ assert(ret_uid);
+
+ r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, path, NULL, &f);
+ if (r < 0)
+ return r;
+
+ if (stat(f, &stats) < 0)
+ return -errno;
+
+ r = stat_verify_directory(&stats);
+ if (r < 0)
+ return r;
+
+ *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:
+ free_many_charp(v, n);
+ 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;
+}
+
+int cg_is_delegated(const char *path) {
+ int r;
+
+ assert(path);
+
+ r = cg_get_xattr_bool(path, "trusted.delegate");
+ if (!ERRNO_IS_NEG_XATTR_ABSENT(r))
+ return r;
+
+ /* If the trusted xattr isn't set (preferred), then check the untrusted one. Under the assumption
+ * that whoever is trusted enough to own the cgroup, is also trusted enough to decide if it is
+ * delegated or not this should be safe. */
+ r = cg_get_xattr_bool(path, "user.delegate");
+ return ERRNO_IS_NEG_XATTR_ABSENT(r) ? false : r;
+}
+
+int cg_is_delegated_fd(int fd) {
+ int r;
+
+ assert(fd >= 0);
+
+ r = getxattr_at_bool(fd, /* path= */ NULL, "trusted.delegate", /* flags= */ 0);
+ if (!ERRNO_IS_NEG_XATTR_ABSENT(r))
+ return r;
+
+ r = getxattr_at_bool(fd, /* path= */ NULL, "user.delegate", /* flags= */ 0);
+ return ERRNO_IS_NEG_XATTR_ABSENT(r) ? false : r;
+}
+
+int cg_has_coredump_receive(const char *path) {
+ int r;
+
+ assert(path);
+
+ r = cg_get_xattr_bool(path, "user.coredump_receive");
+ if (ERRNO_IS_NEG_XATTR_ABSENT(r))
+ return false;
+
+ return r;
+}
+
+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);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-19 16:12:19 +0000