Files
runc/pause.go
T
Akihiro Suda 06f789cf26 Disable rootless mode except RootlessCgMgr when executed as the root in userns
This PR decomposes `libcontainer/configs.Config.Rootless bool` into `RootlessEUID bool` and
`RootlessCgroups bool`, so as to make "runc-in-userns" to be more compatible with "rootful" runc.

`RootlessEUID` denotes that runc is being executed as a non-root user (euid != 0) in
the current user namespace. `RootlessEUID` is almost identical to the former `Rootless`
except cgroups stuff.

`RootlessCgroups` denotes that runc is unlikely to have the full access to cgroups.
`RootlessCgroups` is set to false if runc is executed as the root (euid == 0) in the initial namespace.
Otherwise `RootlessCgroups` is set to true.
(Hint: if `RootlessEUID` is true, `RootlessCgroups` becomes true as well)

When runc is executed as the root (euid == 0) in an user namespace (e.g. by Docker-in-LXD, Podman, Usernetes),
`RootlessEUID` is set to false but `RootlessCgroups` is set to true.
So, "runc-in-userns" behaves almost same as "rootful" runc except that cgroups errors are ignored.

This PR does not have any impact on CLI flags and `state.json`.

Note about CLI:
* Now `runc --rootless=(auto|true|false)` CLI flag is only used for setting `RootlessCgroups`.
* Now `runc spec --rootless` is only required when `RootlessEUID` is set to true.
  For runc-in-userns, `runc spec`  without `--rootless` should work, when sufficient numbers of
  UID/GID are mapped.

Note about `$XDG_RUNTIME_DIR` (e.g. `/run/user/1000`):
* `$XDG_RUNTIME_DIR` is ignored if runc is being executed as the root (euid == 0) in the initial namespace, for backward compatibility.
  (`/run/runc` is used)
* If runc is executed as the root (euid == 0) in an user namespace, `$XDG_RUNTIME_DIR` is honored if `$USER != "" && $USER != "root"`.
  This allows unprivileged users to allow execute runc as the root in userns, without mounting writable `/run/runc`.

Note about `state.json`:
* `rootless` is set to true when `RootlessEUID == true && RootlessCgroups == true`.

Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>
2018-09-07 15:05:03 +09:00

75 lines
1.8 KiB
Go

// +build linux
package main
import (
"github.com/sirupsen/logrus"
"github.com/urfave/cli"
)
var pauseCommand = cli.Command{
Name: "pause",
Usage: "pause suspends all processes inside the container",
ArgsUsage: `<container-id>
Where "<container-id>" is the name for the instance of the container to be
paused. `,
Description: `The pause command suspends all processes in the instance of the container.
Use runc list to identiy instances of containers and their current status.`,
Action: func(context *cli.Context) error {
if err := checkArgs(context, 1, exactArgs); err != nil {
return err
}
rootlessCg, err := shouldUseRootlessCgroupManager(context)
if err != nil {
return err
}
if rootlessCg {
logrus.Warnf("runc pause may fail if you don't have the full access to cgroups")
}
container, err := getContainer(context)
if err != nil {
return err
}
if err := container.Pause(); err != nil {
return err
}
return nil
},
}
var resumeCommand = cli.Command{
Name: "resume",
Usage: "resumes all processes that have been previously paused",
ArgsUsage: `<container-id>
Where "<container-id>" is the name for the instance of the container to be
resumed.`,
Description: `The resume command resumes all processes in the instance of the container.
Use runc list to identiy instances of containers and their current status.`,
Action: func(context *cli.Context) error {
if err := checkArgs(context, 1, exactArgs); err != nil {
return err
}
rootlessCg, err := shouldUseRootlessCgroupManager(context)
if err != nil {
return err
}
if rootlessCg {
logrus.Warn("runc resume may fail if you don't have the full access to cgroups")
}
container, err := getContainer(context)
if err != nil {
return err
}
if err := container.Resume(); err != nil {
return err
}
return nil
},
}