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userns: Allow unprivileged reboot

PATCH Applied Li Zefan 3 participants 3 messages Dec 27, 2012 – Jan 2, 2013

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Li Zefan

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#0 lore raw

PATCH 1/1 userns: Allow unprivileged reboot

In a container with its own pid namespace and user namespace, rebooting the system won't reboot the host, but terminate all the processes in it and thus have the container shutdown, so it's safe.

Signed-off-by Li Zefan <[email protected]>
---
 kernel/sys.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
kernel/sys.c +3 -2
index 265b376..24d1ef5 100644
@@ -433,11 +433,12 @@ static DEFINE_MUTEX(reboot_mutex);
 SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
 		void __user *, arg)
 {
+	struct pid_namespace *pid_ns = task_active_pid_ns(current);
 	char buffer[256];
 	int ret = 0;
 
 	/* We only trust the superuser with rebooting the system. */
-	if (!capable(CAP_SYS_BOOT))
+	if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
 		return -EPERM;
 
 	/* For safety, we require "magic" arguments. */

@@ -453,7 +454,7 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
 	 * pid_namespace, the command is handled by reboot_pid_ns() which will
 	 * call do_exit().
 	 */
-	ret = reboot_pid_ns(task_active_pid_ns(current), cmd);
+	ret = reboot_pid_ns(pid_ns, cmd);
 	if (ret)
 		return ret;
Signature · 1 line
1.8.0.2
Applied
#1 lore raw
Quoted 5 lines · Li Zefan

In a container with its own pid namespace and user namespace, rebooting the system won't reboot the host, but terminate all the processes in it and thus have the container shutdown, so it's safe.

Signed-off-by Li Zefan <[email protected]>

Applied to my development tree. It will eventaully make it to my for-next branch.

Eric

Acked-by Serge E. Hallyn on v1 1/1
#2 lore raw
In reply to Li Zefan
Quoted 5 lines · Li Zefan

In a container with its own pid namespace and user namespace, rebooting the system won't reboot the host, but terminate all the processes in it and thus have the container shutdown, so it's safe.

Signed-off-by Li Zefan <[email protected]>

Thanks, Li.

fwiw,

Acked-by Serge E. Hallyn <serge.hallyn-GeWIH/[email protected]>

-serge

Quoted 37 lines
---
 kernel/sys.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
kernel/sys.c +3 -2
index 265b376..24d1ef5 100644
@@ -433,11 +433,12 @@ static DEFINE_MUTEX(reboot_mutex);
 SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
 		void __user *, arg)
 {
+	struct pid_namespace *pid_ns = task_active_pid_ns(current);
 	char buffer[256];
 	int ret = 0;
 
 	/* We only trust the superuser with rebooting the system. */
-	if (!capable(CAP_SYS_BOOT))
+	if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
 		return -EPERM;
 
 	/* For safety, we require "magic" arguments. */

@@ -453,7 +454,7 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
 	 * pid_namespace, the command is handled by reboot_pid_ns() which will
 	 * call do_exit().
 	 */
-	ret = reboot_pid_ns(task_active_pid_ns(current), cmd);
+	ret = reboot_pid_ns(pid_ns, cmd);
 	if (ret)
 		return ret;
Signature · 5 lines
1.8.0.2
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