diff options
Diffstat (limited to 'runsc')
| -rw-r--r-- | runsc/boot/fs.go | 8 | ||||
| -rw-r--r-- | runsc/boot/vfs.go | 35 |
2 files changed, 32 insertions, 11 deletions
diff --git a/runsc/boot/fs.go b/runsc/boot/fs.go index e2c5f5fb1..ddf288456 100644 --- a/runsc/boot/fs.go +++ b/runsc/boot/fs.go @@ -254,7 +254,7 @@ func mustFindFilesystem(name string) fs.Filesystem { // 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) { +func addSubmountOverlay(ctx context.Context, inode *fs.Inode, submounts []string, mf fs.MountSourceFlags) (*fs.Inode, error) { // Construct a ramfs tree of mount points. The contents never // change, so this can be fully caching. There's no real // filesystem backing this tree, so we set the filesystem to @@ -264,7 +264,7 @@ func addSubmountOverlay(ctx context.Context, inode *fs.Inode, submounts []string if err != nil { return nil, fmt.Errorf("creating mount tree: %v", err) } - overlayInode, err := fs.NewOverlayRoot(ctx, inode, mountTree, fs.MountSourceFlags{}) + overlayInode, err := fs.NewOverlayRoot(ctx, inode, mountTree, mf) if err != nil { return nil, fmt.Errorf("adding mount overlay: %v", err) } @@ -741,7 +741,7 @@ func (c *containerMounter) createRootMount(ctx context.Context, conf *config.Con // for submount paths. "/dev" "/sys" "/proc" and "/tmp" are always // mounted even if they are not in the spec. submounts := append(subtargets("/", c.mounts), "/dev", "/sys", "/proc", "/tmp") - rootInode, err = addSubmountOverlay(ctx, rootInode, submounts) + rootInode, err = addSubmountOverlay(ctx, rootInode, submounts, mf) if err != nil { return nil, fmt.Errorf("adding submount overlay: %v", err) } @@ -851,7 +851,7 @@ func (c *containerMounter) mountSubmount(ctx context.Context, conf *config.Confi submounts := subtargets(m.Destination, c.mounts) if len(submounts) > 0 { log.Infof("Adding submount overlay over %q", m.Destination) - inode, err = addSubmountOverlay(ctx, inode, submounts) + inode, err = addSubmountOverlay(ctx, inode, submounts, mf) if err != nil { return fmt.Errorf("adding submount overlay: %v", err) } diff --git a/runsc/boot/vfs.go b/runsc/boot/vfs.go index 66b6cf19b..7844ea28c 100644 --- a/runsc/boot/vfs.go +++ b/runsc/boot/vfs.go @@ -134,7 +134,7 @@ func registerFilesystems(k *kernel.Kernel) error { } func setupContainerVFS2(ctx context.Context, conf *config.Config, mntr *containerMounter, procArgs *kernel.CreateProcessArgs) error { - mns, err := mntr.setupVFS2(ctx, conf, procArgs) + mns, err := mntr.mountAll(conf, procArgs) if err != nil { return fmt.Errorf("failed to setupFS: %w", err) } @@ -149,7 +149,7 @@ func setupContainerVFS2(ctx context.Context, conf *config.Config, mntr *containe return nil } -func (c *containerMounter) setupVFS2(ctx context.Context, conf *config.Config, procArgs *kernel.CreateProcessArgs) (*vfs.MountNamespace, error) { +func (c *containerMounter) mountAll(conf *config.Config, procArgs *kernel.CreateProcessArgs) (*vfs.MountNamespace, error) { log.Infof("Configuring container's file system with VFS2") // Create context with root credentials to mount the filesystem (the current @@ -172,24 +172,44 @@ func (c *containerMounter) setupVFS2(ctx context.Context, conf *config.Config, p if err := c.mountSubmountsVFS2(rootCtx, conf, mns, rootCreds); err != nil { return nil, fmt.Errorf("mounting submounts vfs2: %w", err) } + + if c.root.Readonly || conf.Overlay { + // Switch to ReadOnly after all submounts were setup. + root := mns.Root() + defer root.DecRef(rootCtx) + if err := c.k.VFS().SetMountReadOnly(root.Mount(), true); err != nil { + return nil, fmt.Errorf(`failed to set mount at "/" readonly: %v`, err) + } + } + return mns, nil } +// createMountNamespaceVFS2 creates the container's root mount and namespace. +// The mount is created ReadWrite to allow mount point for submounts to be +// created. ** The caller is responsible to switch to ReadOnly if needed ** func (c *containerMounter) createMountNamespaceVFS2(ctx context.Context, conf *config.Config, creds *auth.Credentials) (*vfs.MountNamespace, error) { fd := c.fds.remove() - opts := p9MountData(fd, conf.FileAccess, true /* vfs2 */) + data := p9MountData(fd, conf.FileAccess, true /* vfs2 */) if conf.OverlayfsStaleRead { // We can't check for overlayfs here because sandbox is chroot'ed and gofer // can only send mount options for specs.Mounts (specs.Root is missing // Options field). So assume root is always on top of overlayfs. - opts = append(opts, "overlayfs_stale_read") + data = append(data, "overlayfs_stale_read") } log.Infof("Mounting root over 9P, ioFD: %d", fd) - mns, err := c.k.VFS().NewMountNamespace(ctx, creds, "", gofer.Name, &vfs.GetFilesystemOptions{ - Data: strings.Join(opts, ","), - }) + opts := &vfs.MountOptions{ + // Always mount as ReadWrite to allow other mounts on top of it. It'll be + // made ReadOnly in the caller (if needed). + ReadOnly: false, + GetFilesystemOptions: vfs.GetFilesystemOptions{ + Data: strings.Join(data, ","), + }, + InternalMount: true, + } + mns, err := c.k.VFS().NewMountNamespace(ctx, creds, "", gofer.Name, opts) if err != nil { return nil, fmt.Errorf("setting up mount namespace: %w", err) } @@ -227,6 +247,7 @@ func (c *containerMounter) mountSubmountsVFS2(ctx context.Context, conf *config. if err := c.k.VFS().SetMountReadOnly(mnt, false); err != nil { return fmt.Errorf("failed to set mount at %q readwrite: %v", submount.Destination, err) } + // Restore back to ReadOnly at the end. defer func() { if err := c.k.VFS().SetMountReadOnly(mnt, true); err != nil { panic(fmt.Sprintf("failed to restore mount at %q back to readonly: %v", submount.Destination, err)) |