Fix sandbox chroot

Sandbox was setting chroot, but was not chaging the working
dir. Added test to ensure this doesn't happen in the future.

PiperOrigin-RevId: 215676270
Change-Id: I14352d3de64a4dcb90e50948119dc8328c9c15e1

8 files changed, 199 insertions, 21 deletions

diff --git a/runsc/test/README.md b/runsc/test/README.md
new file mode 100644
index 000000000..5929cbeb6
--- /dev/null
+++ b/runsc/test/README.md
@@ -0,0 +1,26 @@
+# Tests
+
+The tests defined under this path are verifying functionality beyond what unit
+tests can cover, e.g. integration and end to end tests. Due to their nature,
+they may need extra setup in the test machine and extra configuration to run.
+
+-   **integration:** defines integration tests that uses `docker run` to test
+    functionality.
+-   **image:** basic end to end test for popular images.
+-   **root:** tests that require to be run as root.
+-   **testutil:** utilities library to support the tests.
+
+The following setup steps are required in order to run these tests:
+
+
+     `./runsc/test/install.sh [--runtime <name>]`
+
+The tests expect the runtime name to be provided in the `RUNSC_RUNTIME`
+environment variable (default: `runsc-test`). To run the tests execute:
+
+
+```
+bazel test --test_env=RUNSC_RUNTIME=runsc-test \
+  //runsc/test/image:image_test \
+  //runsc/test/integration:integration_test
+```
diff --git a/runsc/test/image/image_test.go b/runsc/test/image/image_test.go
index 71d992115..341bdc1d5 100644
--- a/runsc/test/image/image_test.go
+++ b/runsc/test/image/image_test.go
@@ -12,17 +12,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package image provides end-to-end image tests for runsc. These tests require
-// docker and runsc to be installed on the machine. To set it up, run:
-//
-//     ./runsc/test/install.sh [--runtime <name>]
-//
-// The tests expect the runtime name to be provided in the RUNSC_RUNTIME
-// environment variable (default: runsc-test).
-//
+// Package image provides end-to-end image tests for runsc.
+
 // Each test calls docker commands to start up a container, and tests that it is
 // behaving properly, like connecting to a port or looking at the output. The
 // container is killed and deleted at the end.
+//
+// Setup instruction in runsc/test/README.md.
 package image
 
 import (
@@ -307,7 +303,7 @@ func TestRuby(t *testing.T) {
 	}
 }
 
-func MainTest(m *testing.M) {
+func TestMain(m *testing.M) {
 	testutil.EnsureSupportedDockerVersion()
 	os.Exit(m.Run())
 }
diff --git a/runsc/test/integration/integration_test.go b/runsc/test/integration/integration_test.go
index 457b5fbf5..5f24aeed5 100644
--- a/runsc/test/integration/integration_test.go
+++ b/runsc/test/integration/integration_test.go
@@ -12,18 +12,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package image provides end-to-end integration tests for runsc. These tests require
-// docker and runsc to be installed on the machine. To set it up, run:
-//
-//     ./runsc/test/install.sh [--runtime <name>]
-//
-// The tests expect the runtime name to be provided in the RUNSC_RUNTIME
-// environment variable (default: runsc-test).
+// Package integration provides end-to-end integration tests for runsc.
 //
 // Each test calls docker commands to start up a container, and tests that it is
-// behaving properly, with various runsc commands. The container is killed and deleted
-// at the end.
-
+// behaving properly, with various runsc commands. The container is killed and
+// deleted at the end.
+//
+// Setup instruction in runsc/test/README.md.
 package integration
 
 import (
@@ -184,7 +179,7 @@ func TestConnectToSelf(t *testing.T) {
 	}
 }
 
-func MainTest(m *testing.M) {
+func TestMain(m *testing.M) {
 	testutil.EnsureSupportedDockerVersion()
 	os.Exit(m.Run())
 }
diff --git a/runsc/test/root/BUILD b/runsc/test/root/BUILD
new file mode 100644
index 000000000..dbc0f1d26
--- /dev/null
+++ b/runsc/test/root/BUILD
@@ -0,0 +1,27 @@
+package(licenses = ["notice"])  # Apache 2.0
+
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "root",
+    srcs = ["root.go"],
+    importpath = "gvisor.googlesource.com/gvisor/runsc/test/root",
+)
+
+go_test(
+    name = "root_test",
+    size = "small",
+    srcs = ["chroot_test.go"],
+    embed = [":root"],
+    tags = [
+        # Requires docker and runsc to be configured before the test runs.
+        # Also test only runs as root.
+        "manual",
+        "local",
+    ],
+    deps = [
+        "//runsc/specutils",
+        "//runsc/test/testutil",
+        "@com_github_syndtr_gocapability//capability:go_default_library",
+    ],
+)
diff --git a/runsc/test/root/chroot_test.go b/runsc/test/root/chroot_test.go
new file mode 100644
index 000000000..5c59e7451
--- /dev/null
+++ b/runsc/test/root/chroot_test.go
@@ -0,0 +1,103 @@
+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package root is used for tests that requires sysadmin privileges run. First,
+// follow the setup instruction in runsc/test/README.md. To run these test:
+//
+//     bazel build //runsc/test/root:root_test
+//     root_test=$(find -L ./bazel-bin/ -executable -type f -name root_test | grep __main__)
+//     sudo RUNSC_RUNTIME=runsc-test ${root_test}
+package root
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"reflect"
+	"sort"
+	"strconv"
+	"strings"
+	"testing"
+
+	"github.com/syndtr/gocapability/capability"
+	"gvisor.googlesource.com/gvisor/runsc/specutils"
+	"gvisor.googlesource.com/gvisor/runsc/test/testutil"
+)
+
+// TestChroot verifies that the sandbox is chroot'd and that mounts are cleaned
+// up after the sandbox is destroyed.
+func TestChroot(t *testing.T) {
+	d := testutil.MakeDocker("chroot-test")
+	if err := d.Run("alpine", "sleep", "10000"); err != nil {
+		t.Fatalf("docker run failed: %v", err)
+	}
+	defer d.CleanUp()
+
+	pid, err := d.SandboxPid()
+	if err != nil {
+		t.Fatalf("Docker.SandboxPid(): %v", err)
+	}
+
+	// Check that sandbox is chroot'ed.
+	chroot, err := filepath.EvalSymlinks(filepath.Join("/proc", strconv.Itoa(pid), "root"))
+	if err != nil {
+		t.Fatalf("error resolving /proc/<pid>/root symlink: %v", err)
+	}
+	if want := "/tmp/runsc-sandbox-chroot-"; !strings.HasPrefix(chroot, want) {
+		t.Errorf("sandbox is not chroot'd, it should be inside: %q, got: %q", want, chroot)
+	}
+
+	path, err := filepath.EvalSymlinks(filepath.Join("/proc", strconv.Itoa(pid), "cwd"))
+	if err != nil {
+		t.Fatalf("error resolving /proc/<pid>/cwd symlink: %v", err)
+	}
+	if chroot != path {
+		t.Errorf("sandbox current dir is wrong, want: %q, got: %q", chroot, path)
+	}
+
+	fi, err := ioutil.ReadDir(chroot)
+	if err != nil {
+		t.Fatalf("error listing %q: %v", chroot, err)
+	}
+	if want, got := 2, len(fi); want != got {
+		t.Fatalf("chroot dir got %d entries, want %d", want, got)
+	}
+
+	// chroot dir is prepared by runsc and should contains only the executable
+	// and /proc.
+	files := []string{fi[0].Name(), fi[1].Name()}
+	sort.Strings(files)
+	if want := []string{"proc", "runsc"}; !reflect.DeepEqual(files, want) {
+		t.Errorf("chroot got children %v, want %v", files, want)
+	}
+
+	d.CleanUp()
+
+	// Check that chroot directory was cleaned up.
+	if _, err := os.Stat(chroot); err == nil || !os.IsNotExist(err) {
+		t.Errorf("chroot directory %q was not deleted: %v", chroot, err)
+	}
+}
+
+func TestMain(m *testing.M) {
+	testutil.EnsureSupportedDockerVersion()
+
+	if !specutils.HasCapabilities(capability.CAP_SYS_ADMIN, capability.CAP_DAC_OVERRIDE) {
+		fmt.Println("Test requires sysadmin privileges to run. Try again with sudo.")
+		os.Exit(1)
+	}
+
+	os.Exit(m.Run())
+}
diff --git a/runsc/test/root/root.go b/runsc/test/root/root.go
new file mode 100644
index 000000000..790f62c29
--- /dev/null
+++ b/runsc/test/root/root.go
@@ -0,0 +1,16 @@
+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package root is empty. See chroot_test.go for description.
+package root
diff --git a/runsc/test/testutil/docker.go b/runsc/test/testutil/docker.go
index 55ca353b8..cf61f2c10 100644
--- a/runsc/test/testutil/docker.go
+++ b/runsc/test/testutil/docker.go
@@ -267,6 +267,19 @@ func (d *Docker) FindPort(sandboxPort int) (int, error) {
 	return port, nil
 }
 
+// SandboxPid returns the PID to the sandbox process.
+func (d *Docker) SandboxPid() (int, error) {
+	out, err := do("inspect", "-f={{.State.Pid}}", d.Name)
+	if err != nil {
+		return -1, fmt.Errorf("error retrieving pid: %v", err)
+	}
+	pid, err := strconv.Atoi(strings.TrimSuffix(string(out), "\n"))
+	if err != nil {
+		return -1, fmt.Errorf("error parsing pid %q: %v", out, err)
+	}
+	return pid, nil
+}
+
 // WaitForOutput calls 'docker logs' to retrieve containers output and searches
 // for the given pattern.
 func (d *Docker) WaitForOutput(pattern string, timeout time.Duration) (string, error) {
diff --git a/runsc/test/testutil/testutil.go b/runsc/test/testutil/testutil.go
index cdc7f78c3..b4664995c 100644
--- a/runsc/test/testutil/testutil.go
+++ b/runsc/test/testutil/testutil.go
@@ -238,7 +238,7 @@ func WaitForHTTP(port int, timeout time.Duration) error {
 }
 
 // RunAsRoot ensures the test runs with CAP_SYS_ADMIN and CAP_SYS_CHROOT. If
-// need it will create a new user namespace and reexecute the test as root
+// needed it will create a new user namespace and re-execute the test as root
 // inside of the namespace. This functionr returns when it's running as root. If
 // it needs to create another process, it will exit from there and not return.
 func RunAsRoot() {
@@ -246,6 +246,8 @@ func RunAsRoot() {
 		return
 	}
 
+	fmt.Println("*** Re-running test as root in new user namespace ***")
+
 	// Current process doesn't have CAP_SYS_ADMIN, create user namespace and run
 	// as root inside that namespace to get it.
 	runtime.LockOSThread()