mirror/runc
1
0
Fork 0
mirror of https://github.com/opencontainers/runc.git synced 2026-07-10 21:53:57 +08:00
Code Issues Packages Projects Releases Wiki Activity

libct: use preopened rootfs more

Browse Source 
This uses preopened rootfs in Chdir and pivotRoot.

While at it, add O_PATH when opening oldroot in pivotRoot.

Co-authored-by: Kir Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: lfbzhm <lifubang@acmcoder.com>
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
(cherry picked from commit 5b094ed1ac)
Signed-off-by: lifubang <lifubang@acmcoder.com>
This commit is contained in:
lfbzhm
2026-03-27 13:27:43 -07:00
committed by lifubang
parent aa769e7dcc
commit 522b4c804e
1 changed files with 6 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files
libcontainer/rootfs_linux.go
+6 -12
View File
@@ -212,7 +212,7 @@ func prepareRootfs(pipe *syncSocket, iConfig *initConfig) (err error) {
// container. It's just cleaner to do this here (at the expense of the
// operation not being perfectly split).
if err := unix.Chdir(config.Rootfs); err != nil {
if err := unix.Fchdir(int(rootFd.Fd())); err != nil {
return &os.PathError{Op: "chdir", Path: config.Rootfs, Err: err}
}
@@ -227,7 +227,7 @@ func prepareRootfs(pipe *syncSocket, iConfig *initConfig) (err error) {
if config.NoPivotRoot {
err = msMoveRoot(config.Rootfs)
} else if config.Namespaces.Contains(configs.NEWNS) {
err = pivotRoot(config.Rootfs)
err = pivotRoot(rootFd)
} else {
err = chroot()
}
@@ -1144,28 +1144,22 @@ func setupPtmx(config *configs.Config) error {
// pivotRoot will call pivot_root such that rootfs becomes the new root
// filesystem, and everything else is cleaned up.
func pivotRoot(rootfs string) error {
func pivotRoot(root *os.File) error {
// While the documentation may claim otherwise, pivot_root(".", ".") is
// actually valid. What this results in is / being the new root but
// /proc/self/cwd being the old root. Since we can play around with the cwd
// with pivot_root this allows us to pivot without creating directories in
// the rootfs. Shout-outs to the LXC developers for giving us this idea.
oldroot, err := linux.Open("/", unix.O_DIRECTORY|unix.O_RDONLY, 0)
oldroot, err := linux.Open("/", unix.O_DIRECTORY|unix.O_RDONLY|unix.O_PATH, 0)
if err != nil {
return err
}
defer unix.Close(oldroot)
newroot, err := linux.Open(rootfs, unix.O_DIRECTORY|unix.O_RDONLY, 0)
if err != nil {
return err
}
defer unix.Close(newroot)
// Change to the new root so that the pivot_root actually acts on it.
if err := unix.Fchdir(newroot); err != nil {
return &os.PathError{Op: "fchdir", Path: "fd " + strconv.Itoa(newroot), Err: err}
if err := unix.Fchdir(int(root.Fd())); err != nil {
return &os.PathError{Op: "chdir", Path: root.Name(), Err: err}
}
if err := unix.PivotRoot(".", "."); err != nil {