linux - 如何从初始 PID 命名空间以外的 PID 命名空间和初始 PID 命名空间调用 reboot()？

Question

manpage of reboot()说

Behavior inside PID namespaces

Since Linux 3.4, if reboot() is called from a PID namespace other
than the initial PID namespace with one of the cmd values listed
below, it performs a "reboot" of that namespace: the "init" process
of the PID namespace is immediately terminated, with the effects
described in pid_namespaces(7).

The values that can be supplied in cmd when calling reboot() in this case are as follows:

LINUX_REBOOT_CMD_RESTART, LINUX_REBOOT_CMD_RESTART2 The "init" process is terminated, and wait(2) in the parent process reports that the child was killed with a SIGHUP signal.

LINUX_REBOOT_CMD_POWER_OFF, LINUX_REBOOT_CMD_HALT The "init" process is terminated, and wait(2) in the parent process reports that the child was killed with a SIGINT signal.

For the other cmd values, reboot() returns -1 and errno is set to
EINVAL.

看完its manpage，我对PID命名空间的理解有限.我想知道如何调用 reboot()

• 来自初始 PID 命名空间以外的 PID 命名空间，以及
• 来自初始 PID namespace ？

Answer 1

您可以使用 nsenter 进入其他 PID 命名空间。从初始 PID 命名空间以外的 PID 命名空间执行重启:

/usr/bin/nsenter -p/proc/PID/ns/pid reboot

如果目标PID为1:

/usr/bin/nsenter -p/proc/1/ns/pid reboot

第二个问题与简单地调用 reboot 相同，因为它会获取当前的 PID 上下文。