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authorGiuseppe Scrivano <gscrivan@redhat.com>2019-09-06 15:30:30 +0200
committerGiuseppe Scrivano <gscrivan@redhat.com>2019-09-12 08:35:26 +0200
commitafd0818326aa37f03a3bc74f0269a06a403db16d (patch)
tree8ebc91774297027f2c244b22a4428222d42fa3ad
parentb94a5e241095a55a6838970148d296e109b2afd1 (diff)
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rootless: automatically create a systemd scope
when running in rootless mode and using systemd as cgroup manager create automatically a systemd scope when the user doesn't own the current cgroup. This solves a couple of issues: on cgroup v2 it is necessary that a process before it can moved to a different cgroup tree must be in a directory owned by the unprivileged user. This is not always true, e.g. when creating a session with su -l. Closes: https://github.com/containers/libpod/issues/3937 Also, for running systemd in a container it was before necessary to specify "systemd-run --scope --user podman ...", now this is done automatically as part of this PR. Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
-rw-r--r--cmd/podman/main_local.go49
-rw-r--r--libpod/oci_internal_linux.go54
-rw-r--r--pkg/cgroups/cgroups_supported.go62
-rw-r--r--pkg/cgroups/cgroups_unsupported.go6
4 files changed, 140 insertions, 31 deletions
diff --git a/cmd/podman/main_local.go b/cmd/podman/main_local.go
index 0feba609b..56874baad 100644
--- a/cmd/podman/main_local.go
+++ b/cmd/podman/main_local.go
@@ -5,6 +5,7 @@ package main
import (
"context"
+ "fmt"
"log/syslog"
"os"
"runtime/pprof"
@@ -18,6 +19,7 @@ import (
"github.com/containers/libpod/pkg/rootless"
"github.com/containers/libpod/pkg/tracing"
"github.com/containers/libpod/pkg/util"
+ "github.com/containers/libpod/utils"
"github.com/opentracing/opentracing-go"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
@@ -120,6 +122,10 @@ func profileOff(cmd *cobra.Command) error {
}
func setupRootless(cmd *cobra.Command, args []string) error {
+ if !rootless.IsRootless() {
+ return nil
+ }
+
matches, err := rootless.ConfigurationMatches()
if err != nil {
return err
@@ -128,9 +134,6 @@ func setupRootless(cmd *cobra.Command, args []string) error {
logrus.Warningf("the current user namespace doesn't match the configuration in /etc/subuid or /etc/subgid")
logrus.Warningf("you can use `%s system migrate` to recreate the user namespace and restart the containers", os.Args[0])
}
- if os.Geteuid() == 0 || cmd == _searchCommand || cmd == _versionCommand || cmd == _mountCommand || cmd == _migrateCommand || strings.HasPrefix(cmd.Use, "help") {
- return nil
- }
podmanCmd := cliconfig.PodmanCommand{
Command: cmd,
@@ -139,6 +142,39 @@ func setupRootless(cmd *cobra.Command, args []string) error {
Remote: remoteclient,
}
+ runtime, err := libpodruntime.GetRuntime(getContext(), &podmanCmd)
+ if err != nil {
+ return errors.Wrapf(err, "could not get runtime")
+ }
+ defer runtime.DeferredShutdown(false)
+
+ // do it only after podman has already re-execed and running with uid==0.
+ if os.Geteuid() == 0 {
+ ownsCgroup, err := cgroups.UserOwnsCurrentSystemdCgroup()
+ if err != nil {
+ return err
+ }
+
+ if !ownsCgroup {
+ unitName := fmt.Sprintf("podman-%d.scope", os.Getpid())
+ if err := utils.RunUnderSystemdScope(os.Getpid(), "user.slice", unitName); err != nil {
+ conf, err := runtime.GetConfig()
+ if err != nil {
+ return err
+ }
+ if conf.CgroupManager == libpod.SystemdCgroupsManager {
+ logrus.Warnf("Failed to add podman to systemd sandbox cgroup: %v", err)
+ } else {
+ logrus.Debugf("Failed to add podman to systemd sandbox cgroup: %v", err)
+ }
+ }
+ }
+ }
+
+ if os.Geteuid() == 0 || cmd == _searchCommand || cmd == _versionCommand || cmd == _mountCommand || cmd == _migrateCommand || strings.HasPrefix(cmd.Use, "help") {
+ return nil
+ }
+
pausePidPath, err := util.GetRootlessPauseProcessPidPath()
if err != nil {
return errors.Wrapf(err, "could not get pause process pid file path")
@@ -158,13 +194,6 @@ func setupRootless(cmd *cobra.Command, args []string) error {
}
// if there is no pid file, try to join existing containers, and create a pause process.
-
- runtime, err := libpodruntime.GetRuntime(getContext(), &podmanCmd)
- if err != nil {
- return errors.Wrapf(err, "could not get runtime")
- }
- defer runtime.DeferredShutdown(false)
-
ctrs, err := runtime.GetRunningContainers()
if err != nil {
logrus.Errorf(err.Error())
diff --git a/libpod/oci_internal_linux.go b/libpod/oci_internal_linux.go
index f9e935d86..4df1e4010 100644
--- a/libpod/oci_internal_linux.go
+++ b/libpod/oci_internal_linux.go
@@ -21,6 +21,7 @@ import (
"github.com/containers/libpod/pkg/cgroups"
"github.com/containers/libpod/pkg/errorhandling"
"github.com/containers/libpod/pkg/lookup"
+ "github.com/containers/libpod/pkg/rootless"
"github.com/containers/libpod/pkg/util"
"github.com/containers/libpod/utils"
"github.com/coreos/go-systemd/activation"
@@ -359,35 +360,46 @@ func startCommandGivenSelinux(cmd *exec.Cmd) error {
// moveConmonToCgroupAndSignal gets a container's cgroupParent and moves the conmon process to that cgroup
// it then signals for conmon to start by sending nonse data down the start fd
func (r *OCIRuntime) moveConmonToCgroupAndSignal(ctr *Container, cmd *exec.Cmd, startFd *os.File, uuid string) error {
+ mustCreateCgroup := true
// If cgroup creation is disabled - just signal.
if ctr.config.NoCgroups {
- return writeConmonPipeData(startFd)
+ mustCreateCgroup = false
}
- cgroupParent := ctr.CgroupParent()
- if r.cgroupManager == SystemdCgroupsManager {
- unitName := createUnitName("libpod-conmon", ctr.ID())
-
- realCgroupParent := cgroupParent
- splitParent := strings.Split(cgroupParent, "/")
- if strings.HasSuffix(cgroupParent, ".slice") && len(splitParent) > 1 {
- realCgroupParent = splitParent[len(splitParent)-1]
+ if rootless.IsRootless() {
+ ownsCgroup, err := cgroups.UserOwnsCurrentSystemdCgroup()
+ if err != nil {
+ return err
}
+ mustCreateCgroup = !ownsCgroup
+ }
- logrus.Infof("Running conmon under slice %s and unitName %s", realCgroupParent, unitName)
- if err := utils.RunUnderSystemdScope(cmd.Process.Pid, realCgroupParent, unitName); err != nil {
- logrus.Warnf("Failed to add conmon to systemd sandbox cgroup: %v", err)
- }
- } else {
- cgroupPath := filepath.Join(ctr.config.CgroupParent, "conmon")
- control, err := cgroups.New(cgroupPath, &spec.LinuxResources{})
- if err != nil {
- logrus.Warnf("Failed to add conmon to cgroupfs sandbox cgroup: %v", err)
+ if mustCreateCgroup {
+ cgroupParent := ctr.CgroupParent()
+ if r.cgroupManager == SystemdCgroupsManager {
+ unitName := createUnitName("libpod-conmon", ctr.ID())
+
+ realCgroupParent := cgroupParent
+ splitParent := strings.Split(cgroupParent, "/")
+ if strings.HasSuffix(cgroupParent, ".slice") && len(splitParent) > 1 {
+ realCgroupParent = splitParent[len(splitParent)-1]
+ }
+
+ logrus.Infof("Running conmon under slice %s and unitName %s", realCgroupParent, unitName)
+ if err := utils.RunUnderSystemdScope(cmd.Process.Pid, realCgroupParent, unitName); err != nil {
+ logrus.Warnf("Failed to add conmon to systemd sandbox cgroup: %v", err)
+ }
} else {
- // we need to remove this defer and delete the cgroup once conmon exits
- // maybe need a conmon monitor?
- if err := control.AddPid(cmd.Process.Pid); err != nil {
+ cgroupPath := filepath.Join(ctr.config.CgroupParent, "conmon")
+ control, err := cgroups.New(cgroupPath, &spec.LinuxResources{})
+ if err != nil {
logrus.Warnf("Failed to add conmon to cgroupfs sandbox cgroup: %v", err)
+ } else {
+ // we need to remove this defer and delete the cgroup once conmon exits
+ // maybe need a conmon monitor?
+ if err := control.AddPid(cmd.Process.Pid); err != nil {
+ logrus.Warnf("Failed to add conmon to cgroupfs sandbox cgroup: %v", err)
+ }
}
}
}
diff --git a/pkg/cgroups/cgroups_supported.go b/pkg/cgroups/cgroups_supported.go
index fcd44dfc8..2a36777d4 100644
--- a/pkg/cgroups/cgroups_supported.go
+++ b/pkg/cgroups/cgroups_supported.go
@@ -3,8 +3,15 @@
package cgroups
import (
+ "bufio"
+ "fmt"
+ "os"
+ "path/filepath"
+ "strings"
"sync"
"syscall"
+
+ "github.com/pkg/errors"
)
var (
@@ -25,3 +32,58 @@ func IsCgroup2UnifiedMode() (bool, error) {
})
return isUnified, isUnifiedErr
}
+
+// UserOwnsCurrentSystemdCgroup checks whether the current EUID owns the
+// current cgroup.
+func UserOwnsCurrentSystemdCgroup() (bool, error) {
+ uid := os.Geteuid()
+
+ cgroup2, err := IsCgroup2UnifiedMode()
+ if err != nil {
+ return false, err
+ }
+
+ f, err := os.Open("/proc/self/cgroup")
+ if err != nil {
+ return false, errors.Wrapf(err, "open file /proc/self/cgroup")
+ }
+ defer f.Close()
+
+ scanner := bufio.NewScanner(f)
+ for scanner.Scan() {
+ line := scanner.Text()
+ parts := strings.SplitN(line, ":", 3)
+
+ if len(parts) < 3 {
+ continue
+ }
+
+ var cgroupPath string
+
+ if cgroup2 {
+ cgroupPath = filepath.Join(cgroupRoot, parts[2])
+ } else {
+ if parts[1] != "name=systemd" {
+ continue
+ }
+ cgroupPath = filepath.Join(cgroupRoot, "systemd", parts[2])
+ }
+
+ st, err := os.Stat(cgroupPath)
+ if err != nil {
+ return false, err
+ }
+ s := st.Sys()
+ if s == nil {
+ return false, fmt.Errorf("error stat cgroup path %s", cgroupPath)
+ }
+
+ if int(s.(*syscall.Stat_t).Uid) != uid {
+ return false, nil
+ }
+ }
+ if err := scanner.Err(); err != nil {
+ return false, errors.Wrapf(err, "parsing file /proc/self/cgroup")
+ }
+ return true, nil
+}
diff --git a/pkg/cgroups/cgroups_unsupported.go b/pkg/cgroups/cgroups_unsupported.go
index 9dc196e42..cd140fbf3 100644
--- a/pkg/cgroups/cgroups_unsupported.go
+++ b/pkg/cgroups/cgroups_unsupported.go
@@ -6,3 +6,9 @@ package cgroups
func IsCgroup2UnifiedMode() (bool, error) {
return false, nil
}
+
+// UserOwnsCurrentSystemdCgroup checks whether the current EUID owns the
+// current cgroup.
+func UserOwnsCurrentSystemdCgroup() (bool, error) {
+ return false, nil
+}