runsc: set up a minimal chroot from the sandbox process

In this case, new mounts are not created in the host mount namspaces, so
tearDownChroot isn't needed, because chroot will be destroyed with a
sandbox mount namespace.

In additional, pivot_root can't be called instead of chroot.

PiperOrigin-RevId: 229250871
Change-Id: I765bdb587d0b8287a6a8efda8747639d37c7e7b6

1 files changed, 0 insertions, 97 deletions

diff --git a/runsc/sandbox/chroot.go b/runsc/sandbox/chroot.go
deleted file mode 100644
index 354049871..000000000
--- a/runsc/sandbox/chroot.go
+++ /dev/null
@@ -1,97 +0,0 @@
-// Copyright 2018 Google LLC
-//
-// 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 sandbox
-
-import (
-	"fmt"
-	"io/ioutil"
-	"os"
-	"path/filepath"
-	"syscall"
-
-	"gvisor.googlesource.com/gvisor/pkg/log"
-	"gvisor.googlesource.com/gvisor/runsc/specutils"
-)
-
-// chrootBinPath is the location inside the chroot where the runsc binary will
-// be mounted.
-const chrootBinPath = "/runsc"
-
-// mountInChroot creates the destination mount point in the given chroot and
-// mounts the source.
-func mountInChroot(chroot, src, dst, typ string, flags uint32) error {
-	chrootDst := filepath.Join(chroot, dst)
-	log.Infof("Mounting %q at %q", src, chrootDst)
-
-	if err := specutils.Mount(src, chrootDst, typ, flags); err != nil {
-		return fmt.Errorf("error mounting %q at %q: %v", src, chrootDst, err)
-	}
-	return nil
-}
-
-// setUpChroot creates an empty directory with runsc mounted at /runsc and proc
-// mounted at /proc.
-func setUpChroot() (string, error) {
-	// Create the chroot directory and make it accessible to all users.
-	chroot, err := ioutil.TempDir("", "runsc-sandbox-chroot-")
-	if err != nil {
-		return "", fmt.Errorf("TempDir() failed: %v", err)
-	}
-	if err := os.Chmod(chroot, 0777); err != nil {
-		return "", fmt.Errorf("Chmod(%q) failed: %v", chroot, err)
-	}
-	log.Infof("Setting up sandbox chroot in %q", chroot)
-
-	// Mount /proc.
-	if err := mountInChroot(chroot, "proc", "/proc", "proc", syscall.MS_NOSUID|syscall.MS_NODEV|syscall.MS_NOEXEC); err != nil {
-		return "", fmt.Errorf("error mounting proc in chroot: %v", err)
-	}
-
-	// Mount runsc at /runsc in the chroot.
-	binPath, err := specutils.BinPath()
-	if err != nil {
-		return "", err
-	}
-	if err := mountInChroot(chroot, binPath, chrootBinPath, "bind", syscall.MS_BIND|syscall.MS_RDONLY); err != nil {
-		return "", fmt.Errorf("error mounting runsc in chroot: %v", err)
-	}
-
-	return chroot, nil
-}
-
-// tearDownChroot unmounts /proc and /runsc from the chroot before deleting the
-// directory.
-func tearDownChroot(chroot string) error {
-	log.Debugf("Removing chroot mounts %q", chroot)
-
-	// Unmount /proc.
-	proc := filepath.Join(chroot, "proc")
-	if err := syscall.Unmount(proc, 0); err != nil {
-		return fmt.Errorf("error unmounting %q: %v", proc, err)
-	}
-
-	// Unmount /runsc.
-	exe := filepath.Join(chroot, chrootBinPath)
-	if err := syscall.Unmount(exe, 0); err != nil {
-		return fmt.Errorf("error unmounting %q: %v", exe, err)
-	}
-
-	// Remove chroot directory.
-	if err := os.RemoveAll(chroot); err != nil {
-		return fmt.Errorf("error removing %q: %v", chroot, err)
-	}
-
-	return nil
-}