mirror of
https://github.com/opencontainers/runc.git
synced 2026-07-11 06:03:57 +08:00
Kir Kolyshkin
ea36045fe1
When the cgroupv2 fs driver is used without setting cgroupsPath, it picks up a path from /proc/self/cgroup. On a host with systemd, such a path can look like (examples from my machines): - /user.slice/user-1000.slice/session-4.scope - /user.slice/user-1000.slice/user@1000.service/gnome-launched-xfce4-terminal.desktop-4260.scope - /user.slice/user-1000.slice/user@1000.service/gnome-terminal-server.service This cgroup already contains processes in it, which prevents to enable controllers for a sub-cgroup (writing to cgroup.subtree_control fails with EBUSY or EOPNOTSUPP). Obviously, a parent cgroup (which does not contain tasks) should be used. Fixes opencontainers/runc/issues/2298 Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
105 lines
3.0 KiB
Go
105 lines
3.0 KiB
Go
/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package fs2
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import (
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"bufio"
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"io"
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"os"
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"path/filepath"
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"strings"
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"github.com/opencontainers/runc/libcontainer/configs"
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libcontainerUtils "github.com/opencontainers/runc/libcontainer/utils"
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"github.com/pkg/errors"
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)
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const UnifiedMountpoint = "/sys/fs/cgroup"
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func defaultDirPath(c *configs.Cgroup) (string, error) {
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if (c.Name != "" || c.Parent != "") && c.Path != "" {
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return "", errors.Errorf("cgroup: either Path or Name and Parent should be used, got %+v", c)
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}
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if len(c.Paths) != 0 {
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// never set by specconv
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return "", errors.Errorf("cgroup: Paths is unsupported, use Path, got %+v", c)
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}
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// XXX: Do not remove this code. Path safety is important! -- cyphar
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cgPath := libcontainerUtils.CleanPath(c.Path)
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cgParent := libcontainerUtils.CleanPath(c.Parent)
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cgName := libcontainerUtils.CleanPath(c.Name)
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ownCgroup, err := parseCgroupFile("/proc/self/cgroup")
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if err != nil {
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return "", err
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}
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// The current user scope most probably has tasks in it already,
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// making it impossible to enable controllers for its sub-cgroup.
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// A parent cgroup (with no tasks in it) is what we need.
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ownCgroup = filepath.Dir(ownCgroup)
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return _defaultDirPath(UnifiedMountpoint, cgPath, cgParent, cgName, ownCgroup)
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}
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func _defaultDirPath(root, cgPath, cgParent, cgName, ownCgroup string) (string, error) {
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if (cgName != "" || cgParent != "") && cgPath != "" {
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return "", errors.New("cgroup: either Path or Name and Parent should be used")
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}
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innerPath := cgPath
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if innerPath == "" {
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innerPath = filepath.Join(cgParent, cgName)
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}
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if filepath.IsAbs(innerPath) {
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return filepath.Join(root, innerPath), nil
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}
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return filepath.Join(root, ownCgroup, innerPath), nil
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}
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// parseCgroupFile parses /proc/PID/cgroup file and return string
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func parseCgroupFile(path string) (string, error) {
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f, err := os.Open(path)
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if err != nil {
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return "", err
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}
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defer f.Close()
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return parseCgroupFromReader(f)
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}
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func parseCgroupFromReader(r io.Reader) (string, error) {
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var (
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s = bufio.NewScanner(r)
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)
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for s.Scan() {
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var (
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text = s.Text()
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parts = strings.SplitN(text, ":", 3)
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)
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if len(parts) < 3 {
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return "", errors.Errorf("invalid cgroup entry: %q", text)
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}
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// text is like "0::/user.slice/user-1001.slice/session-1.scope"
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if parts[0] == "0" && parts[1] == "" {
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return parts[2], nil
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}
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}
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if err := s.Err(); err != nil {
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return "", err
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}
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return "", errors.New("cgroup path not found")
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}
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