[CRIU] [PATCH] tty: Make sure no /dev/tty inheritance exist

[Andrey Vagin]

Accepted, thanks!

On Fri, Apr 28, 2017 at 04:18:38PM +0300, Cyrill Gorcunov wrote:
> Currently we support restoring opened /dev/tty reference
> if only control terminal belongs to the same process,
> ie no inheritance is allowed.
> 
> Thus we should refuse to dump in such scenario
> otherwise restore will fail.
> 
> Reported-by: Stanislav Kinsburskiy <skinsbursky at virtuozzo.com>
> Signed-off-by: Cyrill Gorcunov <gorcunov at virtuozzo.com>
> ---
>  criu/tty.c | 39 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
> 
> diff --git a/criu/tty.c b/criu/tty.c
> index ade559ce0ce1..1d65c86f78ac 100644
> --- a/criu/tty.c
> +++ b/criu/tty.c
> @@ -114,6 +114,7 @@ struct tty_dump_info {
>  	u32				id;
>  	pid_t				sid;
>  	pid_t				pgrp;
> +	pid_t				pid_real;
>  	int				fd;
>  	int				mnt_id;
>  	struct tty_driver		*driver;
> @@ -1752,6 +1753,7 @@ static int dump_tty_info(int lfd, u32 id, const struct fd_parms *p, struct tty_d
>  	dinfo->id		= id;
>  	dinfo->sid		= pti->sid;
>  	dinfo->pgrp		= pti->pgrp;
> +	dinfo->pid_real		= p->pid;
>  	dinfo->fd		= p->fd;
>  	dinfo->mnt_id		= p->mnt_id;
>  	dinfo->driver		= driver;
> @@ -2111,8 +2113,45 @@ static int tty_dump_queued_data(void)
>  	return ret;
>  }
>  
> +static int tty_verify_ctty(void)
> +{
> +	struct tty_dump_info *d, *p;
> +
> +	list_for_each_entry(d, &all_ttys, list) {
> +		struct tty_dump_info *n = NULL;
> +
> +		if (d->driver->type != TTY_TYPE__CTTY)
> +			continue;
> +
> +		list_for_each_entry(p, &all_ttys, list) {
> +			if (!is_pty(p->driver)	||
> +			    p->sid != d->sid	||
> +			    p->pgrp != d->sid)
> +				continue;
> +			n = p;
> +			break;
> +		}
> +
> +		if (!n) {
> +			pr_err("ctty inheritance detected sid/pgrp %d, "
> +			       "no PTY peer with sid/pgrp needed\n",
> +			       d->sid);
> +			return -ENOENT;
> +		} else if (n->pid_real != d->pid_real) {
> +			pr_err("ctty inheritance detected sid/pgrp %d "
> +			       "(ctty pid_real %d pty pid_real %d)\n",
> +			       d->sid, d->pid_real, n->pid_real);
> +			return -ENOENT;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  int tty_post_actions(void)
>  {
> +	if (tty_verify_ctty())
> +		return -1;
>  	if (tty_verify_active_pairs(NULL))
>  		return -1;
>  	else if (tty_dump_queued_data())
> -- 
> 2.7.4
>