libct: Signal: honor RootlessCgroups

`signalAllProcesses()` depends on the cgroup and is expected to fail
when runc is running in rootless without an access to the cgroup.

Fix issue 4394

Signed-off-by: Akihiro Suda <[email protected]>

libcontainer/container_linux.go

@@ -388,11 +388,18 @@ func (c *Container) Signal(s os.Signal) error {
  // leftover processes. Handle this special case here.
  if s == unix.SIGKILL && !c.config.Namespaces.IsPrivate(configs.NEWPID) {
  if err := signalAllProcesses(c.cgroupManager, unix.SIGKILL); err != nil {
+ if c.config.RootlessCgroups { // may not have an access to cgroup
+ return c.signal(s)
+ }
  return fmt.Errorf("unable to kill all processes: %w", err)
  }
  return nil
  }
 
+ return c.signal(s)
+}
+
+func (c *Container) signal(s os.Signal) error {
  // To avoid a PID reuse attack, don't kill non-running container.
  if !c.hasInit() {
  return ErrNotRunning

libcontainer/state_linux.go

@@ -44,6 +44,7 @@ func destroy(c *Container) error {
  // and destroy is supposed to remove all the container resources, we need
  // to kill those processes here.
  if !c.config.Namespaces.IsPrivate(configs.NEWPID) {
+ // Likely to fail when c.config.RootlessCgroups is true
  _ = signalAllProcesses(c.cgroupManager, unix.SIGKILL)
  }
  if err := c.cgroupManager.Destroy(); err != nil {

tests/integration/kill.bats

@@ -133,3 +133,27 @@ test_host_pidns_kill() {
  test_host_pidns_kill
  unset KILL_INIT
 }
+
+# https://github.com/opencontainers/runc/issues/4394 (cgroup v1, rootless)
+@test "kill KILL [shared pidns]" {
+ update_config '.process.args = ["sleep", "infinity"]'
+
+ runc run -d --console-socket "$CONSOLE_SOCKET" target_ctr
+ [ "$status" -eq 0 ]
+ testcontainer target_ctr running
+ target_pid="$(__runc state target_ctr | jq .pid)"
+ update_config '.linux.namespaces |= map(if .type == "user" or .type == "pid" then (.path = "/proc/'"$target_pid"'/ns/" + .type) else . end) | del(.linux.uidMappings) | del(.linux.gidMappings)'
+
+ runc run -d --console-socket "$CONSOLE_SOCKET" attached_ctr
+ testcontainer attached_ctr running
+ [ "$status" -eq 0 ]
+
+ runc kill attached_ctr 9
+ [ "$status" -eq 0 ]
+
+ runc delete --force attached_ctr
+ [ "$status" -eq 0 ]
+
+ runc delete --force target_ctr
+ [ "$status" -eq 0 ]
+}