config.json failed(permission denied) "chdir to cwd (\"/\") set"

[Taeung]

Hi,

This problem occurs when running runc run test.

I wonder the cause of this problem and how to fix it,
however, I didn't yet find out it..

Preparation:

I got rootfs/ from https://alpinelinux.org/downloads/

$ curl -O http://dl-cdn.alpinelinux.org/alpine/v3.7/releases/x86_64/alpine-minirootfs-3.7.0-x86_64.tar.gz

$ mkdir rootfs && tar xf alpine-minirootfs-3.7.0-x86_64.tar.gz -C rootfs

$ runc spec && ls
config.json  rootfs

Problem situation:

$ sudo runc run test
container_linux.go:348: starting container process caused "chdir to cwd (\"/\") set in config.json failed: permission denied"

This problem seems to be related with:

1. libcontainer/init_linux.go:154~157

119 func finalizeNamespace(config *initConfig) error {
...
154         if config.Cwd != "" {
155                 if err := unix.Chdir(config.Cwd); err != nil {
156                         return fmt.Errorf("chdir to cwd (%q) set in config.json failed: %v", config.Cwd, err)

2. libcontainer/container_linux.go:348

338 func (c *linuxContainer) start(process *Process, isInit bool) error {
339         parent, err := c.newParentProcess(process, isInit)
340         if err != nil {
341                 return newSystemErrorWithCause(err, "creating new parent process")
342         }
343         if err := parent.start(); err != nil {
344                 // terminate the process to ensure that it properly is reaped.                                    
345                 if err := ignoreTerminateErrors(parent.terminate()); err != nil {
346                         logrus.Warn(err)
347                 }
348                 return newSystemErrorWithCause(err, "starting container process")
349         }

But I don't know the specific reason very well..
This problem came from alpinelinux rootfs/ ?
(cf. busybox example is OK)

I'd appreciate it, if you help this.

[ldd91]

I met the same problem

[EricJeffrey]

Apparently, #2086 has shown the reason:
Cwd is not owned by root.
So chown will do