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systemd/src/basic/cgroup-util.c
Lennart Poettering 6414203cfc cgroup-util: add cg_is_delegated_fd() helper 
This is just like cg_is_delegate() but operates on an fd instead of a
cgroup path.

Sooner or later we should access cgroupfs mostly via fds rather than
paths, but we aren't there yet. But let's at least get started.
2023-10-26 09:27:27 +02:00

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/* 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);
}
/**
* 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);
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