podman/libpod/util_linux.go
Daniel J Walsh b4fa6f4f08
Fix SELinux labels of volumes
If we attempt to label a volume and the file system
does not support labeling, then just warn.  SELinux
may or may not work, on the volume.

There is no way to setup a private label on a newly
created volume without using the container mountlabel.

If we don't have a mount label at the time of creation of
the volume, the only option we have is to create a shared
label.

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>
2020-02-13 21:42:57 -05:00

124 lines
3.5 KiB
Go

// +build linux
package libpod
import (
"fmt"
"strings"
"syscall"
"github.com/containers/libpod/libpod/define"
"github.com/containers/libpod/pkg/cgroups"
"github.com/containers/libpod/pkg/rootless"
"github.com/opencontainers/selinux/go-selinux/label"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"golang.org/x/sys/unix"
)
// systemdSliceFromPath makes a new systemd slice under the given parent with
// the given name.
// The parent must be a slice. The name must NOT include ".slice"
func systemdSliceFromPath(parent, name string) (string, error) {
cgroupPath, err := assembleSystemdCgroupName(parent, name)
if err != nil {
return "", err
}
logrus.Debugf("Created cgroup path %s for parent %s and name %s", cgroupPath, parent, name)
if err := makeSystemdCgroup(cgroupPath); err != nil {
return "", errors.Wrapf(err, "error creating cgroup %s", cgroupPath)
}
logrus.Debugf("Created cgroup %s", cgroupPath)
return cgroupPath, nil
}
func getDefaultSystemdCgroup() string {
if rootless.IsRootless() {
return SystemdDefaultRootlessCgroupParent
}
return SystemdDefaultCgroupParent
}
// makeSystemdCgroup creates a systemd CGroup at the given location.
func makeSystemdCgroup(path string) error {
controller, err := cgroups.NewSystemd(getDefaultSystemdCgroup())
if err != nil {
return err
}
if rootless.IsRootless() {
return controller.CreateSystemdUserUnit(path, rootless.GetRootlessUID())
}
return controller.CreateSystemdUnit(path)
}
// deleteSystemdCgroup deletes the systemd cgroup at the given location
func deleteSystemdCgroup(path string) error {
controller, err := cgroups.NewSystemd(getDefaultSystemdCgroup())
if err != nil {
return err
}
if rootless.IsRootless() {
conn, err := cgroups.GetUserConnection(rootless.GetRootlessUID())
if err != nil {
return err
}
defer conn.Close()
return controller.DeleteByPathConn(path, conn)
}
return controller.DeleteByPath(path)
}
// assembleSystemdCgroupName creates a systemd cgroup path given a base and
// a new component to add.
// The base MUST be systemd slice (end in .slice)
func assembleSystemdCgroupName(baseSlice, newSlice string) (string, error) {
const sliceSuffix = ".slice"
if !strings.HasSuffix(baseSlice, sliceSuffix) {
return "", errors.Wrapf(define.ErrInvalidArg, "cannot assemble cgroup path with base %q - must end in .slice", baseSlice)
}
noSlice := strings.TrimSuffix(baseSlice, sliceSuffix)
final := fmt.Sprintf("%s/%s-%s%s", baseSlice, noSlice, newSlice, sliceSuffix)
return final, nil
}
// LabelVolumePath takes a mount path for a volume and gives it an
// selinux label of either shared or not
func LabelVolumePath(path string) error {
_, mountLabel, err := label.InitLabels([]string{})
if err != nil {
return errors.Wrapf(err, "error getting default mountlabels")
}
if err := label.ReleaseLabel(mountLabel); err != nil {
return errors.Wrapf(err, "error releasing label %q", mountLabel)
}
if err := label.Relabel(path, mountLabel, true); err != nil {
if err != syscall.ENOTSUP {
logrus.Debugf("Labeling not supported on %q", path)
} else {
return errors.Wrapf(err, "error setting selinux label for %s to %q as shared", path, mountLabel)
}
}
return nil
}
// Unmount umounts a target directory
func Unmount(mount string) {
if err := unix.Unmount(mount, unix.MNT_DETACH); err != nil {
if err != syscall.EINVAL {
logrus.Warnf("failed to unmount %s : %v", mount, err)
} else {
logrus.Debugf("failed to unmount %s : %v", mount, err)
}
}
}