nspawn-cgroup.c revision b5efdb8af40ea759a1ea584c1bc44ecc81dd00ce
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2015 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <sys/mount.h>
#include "alloc-util.h"
#include "cgroup-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "mkdir.h"
#include "nspawn-cgroup.h"
#include "string-util.h"
#include "strv.h"
#include "util.h"
int chown_cgroup(pid_t pid, uid_t uid_shift) {
_cleanup_free_ char *path = NULL, *fs = NULL;
_cleanup_close_ int fd = -1;
const char *fn;
int r;
r = cg_pid_get_path(NULL, pid, &path);
if (r < 0)
return log_error_errno(r, "Failed to get container cgroup path: %m");
r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, path, NULL, &fs);
if (r < 0)
return log_error_errno(r, "Failed to get file system path for container cgroup: %m");
fd = open(fs, O_RDONLY|O_CLOEXEC|O_DIRECTORY);
if (fd < 0)
return log_error_errno(errno, "Failed to open %s: %m", fs);
FOREACH_STRING(fn,
".",
"tasks",
"notify_on_release",
"cgroup.procs",
"cgroup.clone_children",
"cgroup.controllers",
"cgroup.subtree_control",
"cgroup.populated")
if (fchownat(fd, fn, uid_shift, uid_shift, 0) < 0)
log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING, errno,
"Failed to chown() cgroup file %s, ignoring: %m", fn);
return 0;
}
int sync_cgroup(pid_t pid, bool unified_requested) {
_cleanup_free_ char *cgroup = NULL;
char tree[] = "/tmp/unifiedXXXXXX", pid_string[DECIMAL_STR_MAX(pid) + 1];
bool undo_mount = false;
const char *fn;
int unified, r;
unified = cg_unified();
if (unified < 0)
return log_error_errno(unified, "Failed to determine whether the unified hierachy is used: %m");
if ((unified > 0) == unified_requested)
return 0;
/* When the host uses the legacy cgroup setup, but the
* container shall use the unified hierarchy, let's make sure
* we copy the path from the name=systemd hierarchy into the
* unified hierarchy. Similar for the reverse situation. */
r = cg_pid_get_path(SYSTEMD_CGROUP_CONTROLLER, pid, &cgroup);
if (r < 0)
return log_error_errno(r, "Failed to get control group of " PID_FMT ": %m", pid);
/* In order to access the unified hierarchy we need to mount it */
if (!mkdtemp(tree))
return log_error_errno(errno, "Failed to generate temporary mount point for unified hierarchy: %m");
if (unified)
r = mount("cgroup", tree, "cgroup", MS_NOSUID|MS_NOEXEC|MS_NODEV, "none,name=systemd,xattr");
else
r = mount("cgroup", tree, "cgroup", MS_NOSUID|MS_NOEXEC|MS_NODEV, "__DEVEL__sane_behavior");
if (r < 0) {
r = log_error_errno(errno, "Failed to mount unified hierarchy: %m");
goto finish;
}
undo_mount = true;
fn = strjoina(tree, cgroup, "/cgroup.procs");
(void) mkdir_parents(fn, 0755);
sprintf(pid_string, PID_FMT, pid);
r = write_string_file(fn, pid_string, 0);
if (r < 0)
log_error_errno(r, "Failed to move process: %m");
finish:
if (undo_mount)
(void) umount(tree);
(void) rmdir(tree);
return r;
}
int create_subcgroup(pid_t pid, bool unified_requested) {
_cleanup_free_ char *cgroup = NULL;
const char *child;
int unified, r;
CGroupMask supported;
/* In the unified hierarchy inner nodes may only only contain
* subgroups, but not processes. Hence, if we running in the
* unified hierarchy and the container does the same, and we
* did not create a scope unit for the container move us and
* the container into two separate subcgroups. */
if (!unified_requested)
return 0;
unified = cg_unified();
if (unified < 0)
return log_error_errno(unified, "Failed to determine whether the unified hierachy is used: %m");
if (unified == 0)
return 0;
r = cg_mask_supported(&supported);
if (r < 0)
return log_error_errno(r, "Failed to determine supported controllers: %m");
r = cg_pid_get_path(SYSTEMD_CGROUP_CONTROLLER, 0, &cgroup);
if (r < 0)
return log_error_errno(r, "Failed to get our control group: %m");
child = strjoina(cgroup, "/payload");
r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, child, pid);
if (r < 0)
return log_error_errno(r, "Failed to create %s subcgroup: %m", child);
child = strjoina(cgroup, "/supervisor");
r = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, child, 0);
if (r < 0)
return log_error_errno(r, "Failed to create %s subcgroup: %m", child);
/* Try to enable as many controllers as possible for the new payload. */
(void) cg_enable_everywhere(supported, supported, cgroup);
return 0;
}