This patch adds a test for the shared HOST Pid namespace

It also kills all processes in a cgroup if you are not using the pid namespace

If we stop using the PID namespace, and more then one process is running
when the pid 1 exits, docker will hang since the cgroups do not disappear.

This code will kill all remaining processes

Add Tests for handing of Pid Namespaces

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)

integration/exec_test.go

@@ -67,7 +67,7 @@ func TestIPCPrivate(t *testing.T) {
 	}
 
 	if actual := strings.Trim(buffers.Stdout.String(), "\n"); actual == l {
-		t.Fatalf("ipc link should be private to the conatiner but equals host %q %q", actual, l)
+		t.Fatalf("ipc link should be private to the container but equals host %q %q", actual, l)
 	}
 }
 
@@ -152,7 +152,7 @@ func TestIPCBadPath(t *testing.T) {
 
 	_, _, err = runContainer(config, "", "true")
 	if err == nil {
-		t.Fatal("container succeded with bad ipc path")
+		t.Fatal("container succeeded with bad ipc path")
 	}
 }
 
@@ -176,3 +176,34 @@ func TestRlimit(t *testing.T) {
 		t.Fatalf("expected rlimit to be 1024, got %s", limit)
 	}
 }
+
+func TestPIDNSPrivate(t *testing.T) {
+	if testing.Short() {
+		return
+	}
+
+	rootfs, err := newRootFs()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer remove(rootfs)
+
+	l, err := os.Readlink("/proc/1/ns/pid")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	config := newTemplateConfig(rootfs)
+	buffers, exitCode, err := runContainer(config, "", "readlink", "/proc/self/ns/pid")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if exitCode != 0 {
+		t.Fatalf("exit code not 0. code %d stderr %q", exitCode, buffers.Stderr)
+	}
+
+	if actual := strings.Trim(buffers.Stdout.String(), "\n"); actual == l {
+		t.Fatalf("pid link should be private to the container but equals host %q %q", actual, l)
+	}
+}

namespaces/exec.go

@@ -110,9 +110,40 @@ func Exec(container *libcontainer.Config, stdin io.Reader, stdout, stderr io.Wri
 			return -1, err
 		}
 	}
+	if !container.Namespaces.Contains(libcontainer.NEWPID) {
+		killAllPids(container)
+	}
 	return command.ProcessState.Sys().(syscall.WaitStatus).ExitStatus(), nil
 }
 
+func killAllPids(container *libcontainer.Config) {
+	var (
+		pids []int
+		err  error
+	)
+	freeze := fs.Freeze
+	getPids := fs.GetPids
+	if systemd.UseSystemd() {
+		freeze = systemd.Freeze
+		getPids = systemd.GetPids
+	}
+
+	freeze(container.Cgroups, cgroups.Frozen)
+	if pids, err = getPids(container.Cgroups); err == nil {
+		for _, pid := range pids {
+			if p, err := os.FindProcess(pid); err == nil {
+				p.Kill()
+			}
+		}
+	}
+	freeze(container.Cgroups, cgroups.Thawed)
+	for _, pid := range pids {
+		if p, err := os.FindProcess(pid); err == nil {
+			p.Wait()
+		}
+	}
+}
+
 // DefaultCreateCommand will return an exec.Cmd with the Cloneflags set to the proper namespaces
 // defined on the container's configuration and use the current binary as the init with the
 // args provided