| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Mon, 05 Dec 2011 12:35:27 -0600
From: Serge Hallyn <serge.hallyn@...onical.com>
To: Daniel Lezcano <daniel.lezcano@...e.fr>
CC: akpm@...ux-foundation.org, oleg@...hat.com,
containers@...ts.linux-foundation.org, gkurz@...ibm.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1][V3] Add reboot_pid_ns to handle the reboot syscall
On 12/04/2011 02:24 PM, Daniel Lezcano wrote:
> In the case of a child pid namespace, rebooting the system does not
> really makes sense. When the pid namespace is used in conjunction
> with the other namespaces in order to create a linux container, the
> reboot syscall leads to some problems.
>
> A container can reboot the host. That can be fixed by dropping
> the sys_reboot capability but we are unable to correctly to poweroff/
> halt/reboot a container and the container stays stuck at the shutdown
> time with the container's init process waiting indefinitively.
>
> After several attempts, no solution from userspace was found to reliabily
> handle the shutdown from a container.
>
> This patch propose to store the reboot value in the 16 upper bits of the
> exit code from the processes belonging to a pid namespace which has
> rebooted. When the reboot syscall is called and we are not in the initial
> pid namespace, we kill the pid namespace.
>
> By this way the parent process of the child pid namespace to know if
> it rebooted or not and take the right decision.
>
> Signed-off-by: Daniel Lezcano<daniel.lezcano@...e.fr>
Tested-by: Serge Hallyn <serge.hallyn@...onical.com>
Tested it with reboot(2), worked as expected.
thanks,
-serge
> Acked-by: Serge Hallyn<serge.hallyn@...onical.com>
> ---
> include/linux/pid_namespace.h | 8 +++++++-
> kernel/pid_namespace.c | 33 +++++++++++++++++++++++++++++++++
> kernel/sys.c | 3 +++
> 3 files changed, 43 insertions(+), 1 deletions(-)
>
> diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
> index e7cf666..3279596 100644
> --- a/include/linux/pid_namespace.h
> +++ b/include/linux/pid_namespace.h
> @@ -32,6 +32,7 @@ struct pid_namespace {
> #endif
> gid_t pid_gid;
> int hide_pid;
> + int reboot;
> };
>
> extern struct pid_namespace init_pid_ns;
> @@ -47,6 +48,7 @@ static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns)
> extern struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *ns);
> extern void free_pid_ns(struct kref *kref);
> extern void zap_pid_ns_processes(struct pid_namespace *pid_ns);
> +extern int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd);
>
> static inline void put_pid_ns(struct pid_namespace *ns)
> {
> @@ -74,11 +76,15 @@ static inline void put_pid_ns(struct pid_namespace *ns)
> {
> }
>
> -
> static inline void zap_pid_ns_processes(struct pid_namespace *ns)
> {
> BUG();
> }
> +
> +static inline int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
> +{
> + BUG();
> +}
> #endif /* CONFIG_PID_NS */
>
> extern struct pid_namespace *task_active_pid_ns(struct task_struct *tsk);
> diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
> index a896839..c7a85ea 100644
> --- a/kernel/pid_namespace.c
> +++ b/kernel/pid_namespace.c
> @@ -15,6 +15,7 @@
> #include<linux/acct.h>
> #include<linux/slab.h>
> #include<linux/proc_fs.h>
> +#include<linux/reboot.h>
>
> #define BITS_PER_PAGE (PAGE_SIZE*8)
>
> @@ -187,6 +188,9 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
> rc = sys_wait4(-1, NULL, __WALL, NULL);
> } while (rc != -ECHILD);
>
> + if (pid_ns->reboot)
> + current->signal->group_exit_code = pid_ns->reboot;
> +
> acct_exit_ns(pid_ns);
> return;
> }
> @@ -221,6 +225,35 @@ static struct ctl_table pid_ns_ctl_table[] = {
>
> static struct ctl_path kern_path[] = { { .procname = "kernel", }, { } };
>
> +int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd)
> +{
> + switch(cmd) {
> + case LINUX_REBOOT_CMD_RESTART2:
> + case LINUX_REBOOT_CMD_RESTART:
> + pid_ns->reboot = SYSTEM_RESTART<< 16;
> + break;
> +
> + case LINUX_REBOOT_CMD_HALT:
> + pid_ns->reboot = SYSTEM_HALT<< 16;
> + break;
> +
> + case LINUX_REBOOT_CMD_POWER_OFF:
> + pid_ns->reboot = SYSTEM_POWER_OFF<< 16;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + read_lock(&tasklist_lock);
> + force_sig(SIGKILL, pid_ns->child_reaper);
> + read_unlock(&tasklist_lock);
> +
> + do_exit(0);
> +
> + /* Not reached */
> + return 0;
> +}
> +
> static __init int pid_namespaces_init(void)
> {
> pid_ns_cachep = KMEM_CACHE(pid_namespace, SLAB_PANIC);
> diff --git a/kernel/sys.c b/kernel/sys.c
> index ddf8155..31acf63 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -444,6 +444,9 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
> magic2 != LINUX_REBOOT_MAGIC2C))
> return -EINVAL;
>
> + if (task_active_pid_ns(current) !=&init_pid_ns)
> + return reboot_pid_ns(task_active_pid_ns(current), cmd);
> +
> /* Instead of trying to make the power_off code look like
> * halt when pm_power_off is not set do it the easy way.
> */
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists