The capability CAP_CHECKPOINT_RESTORE was introduced to allow non-root
users to checkpoint and restore processes as non-root with CRIU.
This change extends CAP_CHECKPOINT_RESTORE to enable the CRIU option
'--shell-job' as non-root. CRIU's man-page describes the '--shell-job'
option like this:
Allow one to dump shell jobs. This implies the restored task will
inherit session and process group ID from the criu itself. This option
also allows to migrate a single external tty connection, to migrate
applications like top.
TIOCSLCKTRMIOS can only be done if the process has CAP_SYS_ADMIN and
this change extends it to CAP_SYS_ADMIN or CAP_CHECKPOINT_RESTORE.
With this change it is possible to checkpoint and restore processes
which have a tty connection as non-root if CAP_CHECKPOINT_RESTORE is
set.
Signed-off-by: Adrian Reber <[email protected]>
---
drivers/tty/tty_ioctl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index 4b499301a3db..95d14d7128cc 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -844,7 +844,7 @@ int tty_mode_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
ret = -EFAULT;
return ret;
case TIOCSLCKTRMIOS:
- if (!capable(CAP_SYS_ADMIN))
+ if (!capable(CAP_SYS_ADMIN) && !capable(CAP_CHECKPOINT_RESTORE))
return -EPERM;
copy_termios_locked(real_tty, &kterm);
if (user_termios_to_kernel_termios(&kterm,
@@ -861,7 +861,7 @@ int tty_mode_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
ret = -EFAULT;
return ret;
case TIOCSLCKTRMIOS:
- if (!capable(CAP_SYS_ADMIN))
+ if (!capable(CAP_SYS_ADMIN) && !capable(CAP_CHECKPOINT_RESTORE))
return -EPERM;
copy_termios_locked(real_tty, &kterm);
if (user_termios_to_kernel_termios_1(&kterm,
base-commit: 98b1cc82c4affc16f5598d4fa14b1858671b2263
--
2.43.0
On Wed, Dec 06, 2023 at 02:43:40PM +0100, Adrian Reber wrote:
> The capability CAP_CHECKPOINT_RESTORE was introduced to allow non-root
> users to checkpoint and restore processes as non-root with CRIU.
>
> This change extends CAP_CHECKPOINT_RESTORE to enable the CRIU option
> '--shell-job' as non-root. CRIU's man-page describes the '--shell-job'
> option like this:
>
> Allow one to dump shell jobs. This implies the restored task will
> inherit session and process group ID from the criu itself. This option
> also allows to migrate a single external tty connection, to migrate
> applications like top.
>
> TIOCSLCKTRMIOS can only be done if the process has CAP_SYS_ADMIN and
> this change extends it to CAP_SYS_ADMIN or CAP_CHECKPOINT_RESTORE.
>
> With this change it is possible to checkpoint and restore processes
> which have a tty connection as non-root if CAP_CHECKPOINT_RESTORE is
> set.
>
> Signed-off-by: Adrian Reber <[email protected]>
> ---
> drivers/tty/tty_ioctl.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
> index 4b499301a3db..95d14d7128cc 100644
> --- a/drivers/tty/tty_ioctl.c
> +++ b/drivers/tty/tty_ioctl.c
> @@ -844,7 +844,7 @@ int tty_mode_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
> ret = -EFAULT;
> return ret;
> case TIOCSLCKTRMIOS:
> - if (!capable(CAP_SYS_ADMIN))
> + if (!capable(CAP_SYS_ADMIN) && !capable(CAP_CHECKPOINT_RESTORE))
In both cases you should be able to use:
if (!checkpoint_restore_ns_capable(&init_user_ns))
return -EPERM;
with that fixed,
Acked-by: Christian Brauner <[email protected]>
> return -EPERM;
> copy_termios_locked(real_tty, &kterm);
> if (user_termios_to_kernel_termios(&kterm,
> @@ -861,7 +861,7 @@ int tty_mode_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
> ret = -EFAULT;
> return ret;
> case TIOCSLCKTRMIOS:
> - if (!capable(CAP_SYS_ADMIN))
> + if (!capable(CAP_SYS_ADMIN) && !capable(CAP_CHECKPOINT_RESTORE))
> return -EPERM;
> copy_termios_locked(real_tty, &kterm);
> if (user_termios_to_kernel_termios_1(&kterm,
>
> base-commit: 98b1cc82c4affc16f5598d4fa14b1858671b2263
> --
> 2.43.0
>