776 lines
25 KiB
Go
776 lines
25 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package boot
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import (
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"fmt"
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"path"
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"path/filepath"
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"strconv"
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"strings"
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"syscall"
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// Include filesystem types that OCI spec might mount.
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_ "gvisor.googlesource.com/gvisor/pkg/sentry/fs/dev"
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_ "gvisor.googlesource.com/gvisor/pkg/sentry/fs/host"
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_ "gvisor.googlesource.com/gvisor/pkg/sentry/fs/proc"
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_ "gvisor.googlesource.com/gvisor/pkg/sentry/fs/sys"
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_ "gvisor.googlesource.com/gvisor/pkg/sentry/fs/tmpfs"
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_ "gvisor.googlesource.com/gvisor/pkg/sentry/fs/tty"
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"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
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"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/auth"
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"gvisor.googlesource.com/gvisor/pkg/sentry/limits"
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specs "github.com/opencontainers/runtime-spec/specs-go"
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"gvisor.googlesource.com/gvisor/pkg/abi/linux"
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"gvisor.googlesource.com/gvisor/pkg/log"
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"gvisor.googlesource.com/gvisor/pkg/sentry/context"
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"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
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"gvisor.googlesource.com/gvisor/pkg/sentry/fs/gofer"
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"gvisor.googlesource.com/gvisor/pkg/sentry/fs/ramfs"
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"gvisor.googlesource.com/gvisor/pkg/syserror"
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"gvisor.googlesource.com/gvisor/runsc/specutils"
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)
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const (
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// Filesystem name for 9p gofer mounts.
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rootFsName = "9p"
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// Device name for root mount.
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rootDevice = "9pfs-/"
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// ChildContainersDir is the directory where child container root
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// filesystems are mounted.
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ChildContainersDir = "/__runsc_containers__"
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// Filesystems that runsc supports.
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bind = "bind"
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devpts = "devpts"
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devtmpfs = "devtmpfs"
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proc = "proc"
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sysfs = "sysfs"
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tmpfs = "tmpfs"
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nonefs = "none"
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)
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type fdDispenser struct {
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fds []int
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}
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func (f *fdDispenser) remove() int {
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if f.empty() {
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panic("fdDispenser out of fds")
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}
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rv := f.fds[0]
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f.fds = f.fds[1:]
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return rv
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}
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func (f *fdDispenser) empty() bool {
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return len(f.fds) == 0
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}
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func adjustDirentCache(k *kernel.Kernel) error {
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var hl syscall.Rlimit
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if err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &hl); err != nil {
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return fmt.Errorf("getting RLIMIT_NOFILE: %v", err)
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}
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if int64(hl.Cur) != syscall.RLIM_INFINITY {
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newSize := hl.Cur / 2
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if newSize < gofer.DefaultDirentCacheSize {
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log.Infof("Setting gofer dirent cache size to %d", newSize)
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gofer.DefaultDirentCacheSize = newSize
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k.DirentCacheLimiter = fs.NewDirentCacheLimiter(newSize)
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}
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}
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return nil
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}
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// setupRootContainerFS creates a mount namespace containing the root filesystem
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// and all mounts. 'rootCtx' is used to walk directories to find mount points.
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// 'setMountNS' is called after namespace is created. It must set the mount NS
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// to 'rootCtx'.
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func setupRootContainerFS(userCtx context.Context, rootCtx context.Context, spec *specs.Spec, conf *Config, goferFDs []int, setMountNS func(*fs.MountNamespace)) error {
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mounts := compileMounts(spec)
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// Create a tmpfs mount where we create and mount a root filesystem for
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// each child container.
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mounts = append(mounts, specs.Mount{
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Type: tmpfs,
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Destination: ChildContainersDir,
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})
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fds := &fdDispenser{fds: goferFDs}
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rootInode, err := createRootMount(rootCtx, spec, conf, fds, mounts)
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if err != nil {
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return fmt.Errorf("creating root mount: %v", err)
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}
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mns, err := fs.NewMountNamespace(userCtx, rootInode)
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if err != nil {
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return fmt.Errorf("creating root mount namespace: %v", err)
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}
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setMountNS(mns)
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root := mns.Root()
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defer root.DecRef()
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return mountSubmounts(rootCtx, conf, mns, root, mounts, fds)
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}
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// compileMounts returns the supported mounts from the mount spec, adding any
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// mandatory mounts that are required by the OCI specification.
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func compileMounts(spec *specs.Spec) []specs.Mount {
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// Keep track of whether proc and sys were mounted.
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var procMounted, sysMounted bool
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var mounts []specs.Mount
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// Always mount /dev.
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mounts = append(mounts, specs.Mount{
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Type: devtmpfs,
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Destination: "/dev",
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})
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mounts = append(mounts, specs.Mount{
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Type: devpts,
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Destination: "/dev/pts",
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})
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// Mount all submounts from the spec.
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for _, m := range spec.Mounts {
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if !specutils.IsSupportedDevMount(m) {
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log.Warningf("ignoring dev mount at %q", m.Destination)
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continue
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}
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mounts = append(mounts, m)
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switch filepath.Clean(m.Destination) {
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case "/proc":
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procMounted = true
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case "/sys":
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sysMounted = true
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}
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}
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// Mount proc and sys even if the user did not ask for it, as the spec
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// says we SHOULD.
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var mandatoryMounts []specs.Mount
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if !procMounted {
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mandatoryMounts = append(mandatoryMounts, specs.Mount{
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Type: proc,
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Destination: "/proc",
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})
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}
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if !sysMounted {
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mandatoryMounts = append(mandatoryMounts, specs.Mount{
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Type: sysfs,
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Destination: "/sys",
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})
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}
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// The mandatory mounts should be ordered right after the root, in case
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// there are submounts of these mandatory mounts already in the spec.
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mounts = append(mounts[:0], append(mandatoryMounts, mounts[0:]...)...)
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return mounts
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}
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// createRootMount creates the root filesystem.
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func createRootMount(ctx context.Context, spec *specs.Spec, conf *Config, fds *fdDispenser, mounts []specs.Mount) (*fs.Inode, error) {
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// First construct the filesystem from the spec.Root.
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mf := fs.MountSourceFlags{ReadOnly: spec.Root.Readonly}
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var (
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rootInode *fs.Inode
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err error
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)
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fd := fds.remove()
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log.Infof("Mounting root over 9P, ioFD: %d", fd)
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p9FS := mustFindFilesystem("9p")
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opts := p9MountOptions(fd, conf.FileAccess)
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rootInode, err = p9FS.Mount(ctx, rootDevice, mf, strings.Join(opts, ","), nil)
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if err != nil {
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return nil, fmt.Errorf("creating root mount point: %v", err)
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}
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// We need to overlay the root on top of a ramfs with stub directories
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// for submount paths. "/dev" "/sys" "/proc" and "/tmp" are always
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// mounted even if they are not in the spec.
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submounts := append(subtargets("/", mounts), "/dev", "/sys", "/proc", "/tmp")
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rootInode, err = addSubmountOverlay(ctx, rootInode, submounts)
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if err != nil {
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return nil, fmt.Errorf("adding submount overlay: %v", err)
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}
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if conf.Overlay && !spec.Root.Readonly {
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log.Debugf("Adding overlay on top of root mount")
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// Overlay a tmpfs filesystem on top of the root.
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rootInode, err = addOverlay(ctx, conf, rootInode, "root-overlay-upper", mf)
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if err != nil {
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return nil, err
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}
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}
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log.Infof("Mounted %q to %q type root", spec.Root.Path, "/")
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return rootInode, nil
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}
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func addOverlay(ctx context.Context, conf *Config, lower *fs.Inode, name string, lowerFlags fs.MountSourceFlags) (*fs.Inode, error) {
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// Upper layer uses the same flags as lower, but it must be read-write.
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lowerFlags.ReadOnly = false
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tmpFS := mustFindFilesystem("tmpfs")
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if !fs.IsDir(lower.StableAttr) {
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// Create overlay on top of mount file, e.g. /etc/hostname.
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msrc := fs.NewCachingMountSource(tmpFS, lowerFlags)
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return fs.NewOverlayRootFile(ctx, msrc, lower, lowerFlags)
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}
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// Create overlay on top of mount dir.
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upper, err := tmpFS.Mount(ctx, name+"-upper", lowerFlags, "", nil)
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if err != nil {
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return nil, fmt.Errorf("creating tmpfs overlay: %v", err)
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}
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return fs.NewOverlayRoot(ctx, upper, lower, lowerFlags)
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}
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// getMountNameAndOptions retrieves the fsName, opts, and useOverlay values
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// used for mounts.
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func getMountNameAndOptions(conf *Config, m specs.Mount, fds *fdDispenser) (string, []string, bool, error) {
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var (
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fsName string
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opts []string
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useOverlay bool
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err error
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)
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switch m.Type {
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case devpts, devtmpfs, proc, sysfs:
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fsName = m.Type
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case nonefs:
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fsName = sysfs
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case tmpfs:
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fsName = m.Type
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// tmpfs has some extra supported options that we must pass through.
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opts, err = parseAndFilterOptions(m.Options, "mode", "uid", "gid")
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case bind:
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fd := fds.remove()
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fsName = "9p"
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// Non-root bind mounts are always shared.
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opts = p9MountOptions(fd, FileAccessShared)
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// If configured, add overlay to all writable mounts.
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useOverlay = conf.Overlay && !mountFlags(m.Options).ReadOnly
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default:
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// TODO(nlacasse): Support all the mount types and make this a
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// fatal error. Most applications will "just work" without
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// them, so this is a warning for now.
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// we do not support.
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log.Warningf("ignoring unknown filesystem type %q", m.Type)
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}
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return fsName, opts, useOverlay, err
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}
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func mountSubmounts(ctx context.Context, conf *Config, mns *fs.MountNamespace, root *fs.Dirent, mounts []specs.Mount, fds *fdDispenser) error {
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for _, m := range mounts {
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if err := mountSubmount(ctx, conf, mns, root, fds, m, mounts); err != nil {
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return fmt.Errorf("mount submount %q: %v", m.Destination, err)
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}
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}
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if err := mountTmp(ctx, conf, mns, root, fds, mounts); err != nil {
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return fmt.Errorf("mount submount %q: %v", "tmp", err)
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}
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if !fds.empty() {
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return fmt.Errorf("not all mount points were consumed, remaining: %v", fds)
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}
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return nil
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}
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// mountSubmount mounts volumes inside the container's root. Because mounts may
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// be readonly, a lower ramfs overlay is added to create the mount point dir.
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// Another overlay is added with tmpfs on top if Config.Overlay is true.
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// 'm.Destination' must be an absolute path with '..' and symlinks resolved.
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func mountSubmount(ctx context.Context, conf *Config, mns *fs.MountNamespace, root *fs.Dirent, fds *fdDispenser, m specs.Mount, mounts []specs.Mount) error {
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// Map mount type to filesystem name, and parse out the options that we are
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// capable of dealing with.
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fsName, opts, useOverlay, err := getMountNameAndOptions(conf, m, fds)
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// Return the error or nil that corresponds to the default case in getMountNameAndOptions.
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if err != nil {
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return err
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}
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if fsName == "" {
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return nil
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}
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// All filesystem names should have been mapped to something we know.
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filesystem := mustFindFilesystem(fsName)
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mf := mountFlags(m.Options)
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if useOverlay {
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// All writes go to upper, be paranoid and make lower readonly.
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mf.ReadOnly = true
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}
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inode, err := filesystem.Mount(ctx, mountDevice(m), mf, strings.Join(opts, ","), nil)
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if err != nil {
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return fmt.Errorf("creating mount with source %q: %v", m.Source, err)
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}
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// If there are submounts, we need to overlay the mount on top of a
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// ramfs with stub directories for submount paths.
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submounts := subtargets(m.Destination, mounts)
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if len(submounts) > 0 {
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log.Infof("Adding submount overlay over %q", m.Destination)
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inode, err = addSubmountOverlay(ctx, inode, submounts)
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if err != nil {
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return fmt.Errorf("adding submount overlay: %v", err)
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}
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}
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if useOverlay {
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log.Debugf("Adding overlay on top of mount %q", m.Destination)
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inode, err = addOverlay(ctx, conf, inode, m.Type, mf)
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if err != nil {
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return err
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}
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}
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maxTraversals := uint(0)
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dirent, err := mns.FindInode(ctx, root, root, m.Destination, &maxTraversals)
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if err != nil {
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return fmt.Errorf("can't find mount destination %q: %v", m.Destination, err)
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}
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defer dirent.DecRef()
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if err := mns.Mount(ctx, dirent, inode); err != nil {
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return fmt.Errorf("mount %q error: %v", m.Destination, err)
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}
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log.Infof("Mounted %q to %q type %s", m.Source, m.Destination, m.Type)
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return nil
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}
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// p9MountOptions creates a slice of options for a p9 mount.
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func p9MountOptions(fd int, fa FileAccessType) []string {
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opts := []string{
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"trans=fd",
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"rfdno=" + strconv.Itoa(fd),
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"wfdno=" + strconv.Itoa(fd),
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"privateunixsocket=true",
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}
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if fa == FileAccessShared {
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opts = append(opts, "cache=remote_revalidating")
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}
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return opts
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}
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// parseAndFilterOptions parses a MountOptions slice and filters by the allowed
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// keys.
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func parseAndFilterOptions(opts []string, allowedKeys ...string) ([]string, error) {
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var out []string
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for _, o := range opts {
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kv := strings.Split(o, "=")
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switch len(kv) {
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case 1:
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if specutils.ContainsStr(allowedKeys, o) {
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out = append(out, o)
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continue
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}
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log.Warningf("ignoring unsupported key %q", kv)
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case 2:
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if specutils.ContainsStr(allowedKeys, kv[0]) {
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out = append(out, o)
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continue
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}
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log.Warningf("ignoring unsupported key %q", kv[0])
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default:
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return nil, fmt.Errorf("invalid option %q", o)
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}
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}
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return out, nil
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}
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// mountDevice returns a device string based on the fs type and target
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// of the mount.
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func mountDevice(m specs.Mount) string {
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if m.Type == bind {
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// Make a device string that includes the target, which is consistent across
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// S/R and uniquely identifies the connection.
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return "9pfs-" + m.Destination
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}
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// All other fs types use device "none".
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return "none"
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}
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// addRestoreMount adds a mount to the MountSources map used for restoring a
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// checkpointed container.
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func addRestoreMount(conf *Config, renv *fs.RestoreEnvironment, m specs.Mount, fds *fdDispenser) error {
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fsName, opts, _, err := getMountNameAndOptions(conf, m, fds)
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// Return the error or nil that corresponds to the default case in getMountNameAndOptions.
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if err != nil {
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return err
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}
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// TODO(nlacasse): Fix this when we support all the mount types and
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// make this a fatal error.
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if fsName == "" {
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return nil
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}
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newMount := fs.MountArgs{
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Dev: mountDevice(m),
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Flags: mountFlags(m.Options),
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DataString: strings.Join(opts, ","),
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}
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renv.MountSources[fsName] = append(renv.MountSources[fsName], newMount)
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log.Infof("Added mount at %q: %+v", fsName, newMount)
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return nil
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}
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// createRestoreEnvironment builds a fs.RestoreEnvironment called renv by adding the mounts
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// to the environment.
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func createRestoreEnvironment(spec *specs.Spec, conf *Config, fds *fdDispenser) (*fs.RestoreEnvironment, error) {
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renv := &fs.RestoreEnvironment{
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MountSources: make(map[string][]fs.MountArgs),
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}
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// Add root mount.
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fd := fds.remove()
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opts := p9MountOptions(fd, conf.FileAccess)
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mf := fs.MountSourceFlags{}
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if spec.Root.Readonly {
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mf.ReadOnly = true
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}
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rootMount := fs.MountArgs{
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Dev: rootDevice,
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Flags: mf,
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DataString: strings.Join(opts, ","),
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}
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renv.MountSources[rootFsName] = append(renv.MountSources[rootFsName], rootMount)
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// Add submounts.
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var tmpMounted bool
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for _, m := range compileMounts(spec) {
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if err := addRestoreMount(conf, renv, m, fds); err != nil {
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return nil, err
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}
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if filepath.Clean(m.Destination) == "/tmp" {
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tmpMounted = true
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}
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}
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// TODO(b/67958150): handle '/tmp' properly (see mountTmp()).
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if !tmpMounted {
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tmpMount := specs.Mount{
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Type: tmpfs,
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Destination: "/tmp",
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}
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if err := addRestoreMount(conf, renv, tmpMount, fds); err != nil {
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return nil, err
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}
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}
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return renv, nil
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}
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func mountFlags(opts []string) fs.MountSourceFlags {
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mf := fs.MountSourceFlags{}
|
|
for _, o := range opts {
|
|
switch o {
|
|
case "rw":
|
|
mf.ReadOnly = false
|
|
case "ro":
|
|
mf.ReadOnly = true
|
|
case "noatime":
|
|
mf.NoAtime = true
|
|
case "noexec":
|
|
mf.NoExec = true
|
|
default:
|
|
log.Warningf("ignoring unknown mount option %q", o)
|
|
}
|
|
}
|
|
return mf
|
|
}
|
|
|
|
func mustFindFilesystem(name string) fs.Filesystem {
|
|
fs, ok := fs.FindFilesystem(name)
|
|
if !ok {
|
|
panic(fmt.Sprintf("could not find filesystem %q", name))
|
|
}
|
|
return fs
|
|
}
|
|
|
|
// addSubmountOverlay overlays the inode over a ramfs tree containing the given
|
|
// paths.
|
|
func addSubmountOverlay(ctx context.Context, inode *fs.Inode, submounts []string) (*fs.Inode, error) {
|
|
msrc := fs.NewPseudoMountSource()
|
|
mountTree, err := ramfs.MakeDirectoryTree(ctx, msrc, submounts)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("creating mount tree: %v", err)
|
|
}
|
|
overlayInode, err := fs.NewOverlayRoot(ctx, inode, mountTree, fs.MountSourceFlags{})
|
|
if err != nil {
|
|
return nil, fmt.Errorf("adding mount overlay: %v", err)
|
|
}
|
|
return overlayInode, err
|
|
}
|
|
|
|
// subtargets takes a set of Mounts and returns only the targets that are
|
|
// children of the given root. The returned paths are relative to the root.
|
|
func subtargets(root string, mnts []specs.Mount) []string {
|
|
var targets []string
|
|
for _, mnt := range mnts {
|
|
if relPath, isSubpath := fs.IsSubpath(mnt.Destination, root); isSubpath {
|
|
targets = append(targets, relPath)
|
|
}
|
|
}
|
|
return targets
|
|
}
|
|
|
|
// setupContainerFS is used to set up the file system and amend the procArgs accordingly.
|
|
// procArgs are passed by reference and the FDMap field is modified. It dups stdioFDs.
|
|
func setupContainerFS(procArgs *kernel.CreateProcessArgs, spec *specs.Spec, conf *Config, stdioFDs, goferFDs []int, console bool, creds *auth.Credentials, ls *limits.LimitSet, k *kernel.Kernel, cid string) error {
|
|
ctx := procArgs.NewContext(k)
|
|
|
|
// Create the FD map, which will set stdin, stdout, and stderr. If
|
|
// console is true, then ioctl calls will be passed through to the host
|
|
// fd.
|
|
fdm, err := createFDMap(ctx, k, ls, console, stdioFDs)
|
|
if err != nil {
|
|
return fmt.Errorf("importing fds: %v", err)
|
|
}
|
|
|
|
// CreateProcess takes a reference on FDMap if successful. We
|
|
// won't need ours either way.
|
|
procArgs.FDMap = fdm
|
|
|
|
// Use root user to configure mounts. The current user might not have
|
|
// permission to do so.
|
|
rootProcArgs := kernel.CreateProcessArgs{
|
|
WorkingDirectory: "/",
|
|
Credentials: auth.NewRootCredentials(creds.UserNamespace),
|
|
Umask: 0022,
|
|
MaxSymlinkTraversals: linux.MaxSymlinkTraversals,
|
|
}
|
|
rootCtx := rootProcArgs.NewContext(k)
|
|
|
|
// If this is the root container, we also need to setup the root mount
|
|
// namespace.
|
|
mns := k.RootMountNamespace()
|
|
if mns == nil {
|
|
// Setup the root container.
|
|
return setupRootContainerFS(ctx, rootCtx, spec, conf, goferFDs, func(mns *fs.MountNamespace) {
|
|
k.SetRootMountNamespace(mns)
|
|
})
|
|
}
|
|
|
|
// Setup a child container.
|
|
log.Infof("Creating new process in child container.")
|
|
globalRoot := mns.Root()
|
|
defer globalRoot.DecRef()
|
|
|
|
// Create mount point for the container's rootfs.
|
|
maxTraversals := uint(0)
|
|
contDir, err := mns.FindInode(ctx, globalRoot, nil, ChildContainersDir, &maxTraversals)
|
|
if err != nil {
|
|
return fmt.Errorf("couldn't find child container dir %q: %v", ChildContainersDir, err)
|
|
}
|
|
if err := contDir.CreateDirectory(ctx, globalRoot, cid, fs.FilePermsFromMode(0755)); err != nil {
|
|
return fmt.Errorf("create directory %q: %v", cid, err)
|
|
}
|
|
containerRoot, err := contDir.Walk(ctx, globalRoot, cid)
|
|
if err != nil {
|
|
return fmt.Errorf("walk to %q failed: %v", cid, err)
|
|
}
|
|
defer containerRoot.DecRef()
|
|
|
|
// Create the container's root filesystem mount.
|
|
fds := &fdDispenser{fds: goferFDs}
|
|
rootInode, err := createRootMount(rootCtx, spec, conf, fds, nil)
|
|
if err != nil {
|
|
return fmt.Errorf("creating filesystem for container: %v", err)
|
|
}
|
|
|
|
// Mount the container's root filesystem to the newly created mount point.
|
|
if err := mns.Mount(ctx, containerRoot, rootInode); err != nil {
|
|
return fmt.Errorf("mount container root: %v", err)
|
|
}
|
|
|
|
// We have to re-walk to the dirent to find the mounted
|
|
// directory. The old dirent is invalid at this point.
|
|
containerRoot, err = contDir.Walk(ctx, globalRoot, cid)
|
|
if err != nil {
|
|
return fmt.Errorf("find container mount point %q: %v", cid, err)
|
|
}
|
|
cu := specutils.MakeCleanup(func() { containerRoot.DecRef() })
|
|
defer cu.Clean()
|
|
|
|
log.Infof("Mounted child's root fs to %q", filepath.Join(ChildContainersDir, cid))
|
|
|
|
// Set process root here, so 'rootCtx.Value(CtxRoot)' will return it.
|
|
procArgs.Root = containerRoot
|
|
|
|
// Mount all submounts.
|
|
mounts := compileMounts(spec)
|
|
if err := mountSubmounts(rootCtx, conf, mns, containerRoot, mounts, fds); err != nil {
|
|
return err
|
|
}
|
|
cu.Release()
|
|
return nil
|
|
}
|
|
|
|
// setExecutablePath sets the procArgs.Filename by searching the PATH for an
|
|
// executable matching the procArgs.Argv[0].
|
|
func setExecutablePath(ctx context.Context, mns *fs.MountNamespace, procArgs *kernel.CreateProcessArgs) error {
|
|
paths := fs.GetPath(procArgs.Envv)
|
|
exe := procArgs.Argv[0]
|
|
f, err := mns.ResolveExecutablePath(ctx, procArgs.WorkingDirectory, exe, paths)
|
|
if err != nil {
|
|
return fmt.Errorf("searching for executable %q, cwd: %q, $PATH=%q: %v", exe, procArgs.WorkingDirectory, strings.Join(paths, ":"), err)
|
|
}
|
|
procArgs.Filename = f
|
|
return nil
|
|
}
|
|
|
|
// destroyContainerFS cleans up the filesystem by unmounting all mounts for the
|
|
// given container and deleting the container root directory.
|
|
func destroyContainerFS(ctx context.Context, cid string, k *kernel.Kernel) error {
|
|
defer func() {
|
|
// Flushing dirent references triggers many async close
|
|
// operations. We must wait for those to complete before
|
|
// returning, otherwise the caller may kill the gofer before
|
|
// they complete, causing a cascade of failing RPCs.
|
|
//
|
|
// This must take place in the first deferred function, so that
|
|
// it runs after all the other deferred DecRef() calls in this
|
|
// function.
|
|
log.Infof("Waiting for async filesystem operations to complete")
|
|
fs.AsyncBarrier()
|
|
}()
|
|
|
|
// First get a reference to the container root directory.
|
|
mns := k.RootMountNamespace()
|
|
mnsRoot := mns.Root()
|
|
defer mnsRoot.DecRef()
|
|
containerRoot := path.Join(ChildContainersDir, cid)
|
|
maxTraversals := uint(0)
|
|
containerRootDirent, err := mns.FindInode(ctx, mnsRoot, nil, containerRoot, &maxTraversals)
|
|
if err == syserror.ENOENT {
|
|
// Container must have been destroyed already. That's fine.
|
|
return nil
|
|
}
|
|
if err != nil {
|
|
return fmt.Errorf("finding container root directory %q: %v", containerRoot, err)
|
|
}
|
|
defer containerRootDirent.DecRef()
|
|
|
|
// Iterate through all submounts and unmount them. We unmount lazily by
|
|
// setting detach=true, so we can unmount in any order.
|
|
for _, m := range containerRootDirent.Inode.MountSource.Submounts() {
|
|
root := m.Root()
|
|
defer root.DecRef()
|
|
|
|
// Do a best-effort unmount by flushing the refs and unmount
|
|
// with "detach only = true". Unmount returns EINVAL when the mount point
|
|
// doesn't exist, i.e. it has already been unmounted.
|
|
log.Debugf("Unmounting container submount %q", root.BaseName())
|
|
m.FlushDirentRefs()
|
|
if err := mns.Unmount(ctx, root, true /* detach only */); err != nil && err != syserror.EINVAL {
|
|
return fmt.Errorf("unmounting container submount %q: %v", root.BaseName(), err)
|
|
}
|
|
}
|
|
|
|
// Unmount the container root itself.
|
|
log.Debugf("Unmounting container root %q", containerRoot)
|
|
containerRootDirent.Inode.MountSource.FlushDirentRefs()
|
|
if err := mns.Unmount(ctx, containerRootDirent, true /* detach only */); err != nil {
|
|
return fmt.Errorf("unmounting container root mount %q: %v", containerRootDirent.BaseName(), err)
|
|
}
|
|
|
|
// Get a reference to the parent directory and remove the root
|
|
// container directory.
|
|
maxTraversals = 0
|
|
containersDirDirent, err := mns.FindInode(ctx, mnsRoot, nil, ChildContainersDir, &maxTraversals)
|
|
if err != nil {
|
|
return fmt.Errorf("finding containers directory %q: %v", ChildContainersDir, err)
|
|
}
|
|
defer containersDirDirent.DecRef()
|
|
log.Debugf("Deleting container root %q", containerRoot)
|
|
if err := containersDirDirent.RemoveDirectory(ctx, mnsRoot, cid); err != nil {
|
|
return fmt.Errorf("removing directory %q: %v", containerRoot, err)
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// mountTmp mounts an internal tmpfs at '/tmp' if it's safe to do so.
|
|
// Technically we don't have to mount tmpfs at /tmp, as we could just rely on
|
|
// the host /tmp, but this is a nice optimization, and fixes some apps that call
|
|
// mknod in /tmp. It's unsafe to mount tmpfs if:
|
|
// 1. /tmp is mounted explictly: we should not override user's wish
|
|
// 2. /tmp is not empty: mounting tmpfs would hide existing files in /tmp
|
|
//
|
|
// Note that when there are submounts inside of '/tmp', directories for the
|
|
// mount points must be present, making '/tmp' not empty anymore.
|
|
func mountTmp(ctx context.Context, conf *Config, mns *fs.MountNamespace, root *fs.Dirent, fds *fdDispenser, mounts []specs.Mount) error {
|
|
for _, m := range mounts {
|
|
if filepath.Clean(m.Destination) == "/tmp" {
|
|
log.Debugf("Explict %q mount found, skipping internal tmpfs, mount: %+v", "/tmp", m)
|
|
return nil
|
|
}
|
|
}
|
|
|
|
maxTraversals := uint(0)
|
|
tmp, err := mns.FindInode(ctx, root, root, "tmp", &maxTraversals)
|
|
switch err {
|
|
case nil:
|
|
// Found '/tmp' in filesystem, check if it's empty.
|
|
defer tmp.DecRef()
|
|
f, err := tmp.Inode.GetFile(ctx, tmp, fs.FileFlags{Read: true, Directory: true})
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer f.DecRef()
|
|
serializer := &fs.CollectEntriesSerializer{}
|
|
if err := f.Readdir(ctx, serializer); err != nil {
|
|
return err
|
|
}
|
|
// If more than "." and ".." is found, skip internal tmpfs to prevent hiding
|
|
// existing files.
|
|
if len(serializer.Order) > 2 {
|
|
log.Infof("Skipping internal tmpfs on top %q, because it's not empty", "/tmp")
|
|
return nil
|
|
}
|
|
log.Infof("Mounting internal tmpfs on top of empty %q", "/tmp")
|
|
fallthrough
|
|
|
|
case syserror.ENOENT:
|
|
// No '/tmp' found (or fallthrough from above). Safe to mount internal
|
|
// tmpfs.
|
|
tmpMount := specs.Mount{
|
|
Type: tmpfs,
|
|
Destination: "/tmp",
|
|
}
|
|
return mountSubmount(ctx, conf, mns, root, fds, tmpMount, mounts)
|
|
|
|
default:
|
|
return err
|
|
}
|
|
}
|