linux-kernel - Re: [systemd-devel] [PATCH] tty: Set correct tty name in 'active' sysfs attribute

Open Source and information security mailing list archives

Message-ID: <CANq1E4QM-SwAhBmgGgmKjAHaKW-QZ7GPBkKyrv_=ek1CFmRWEw@mail.gmail.com>
Date:	Wed, 5 Feb 2014 13:53:47 +0100
From:	David Herrmann <dh.herrmann@...il.com>
To:	Hannes Reinecke <hare@...e.de>
Cc:	systemd Mailing List <systemd-devel@...ts.freedesktop.org>,
	Kay Sievers <kay@...y.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [systemd-devel] [PATCH] tty: Set correct tty name in 'active'
 sysfs attribute

Hi

On Wed, Feb 5, 2014 at 11:11 AM, Hannes Reinecke <hare@...e.de> wrote:
> The 'active' sysfs attribute should refer to the currently
> active tty devices the console is running on, not the currently
> active console.
> The console structure doesn't refer to any device in sysfs,
> only the tty the console is running on has.
> So we need to print out the tty names in 'active', not
> the console names.
>
> Cc: Lennart Poettering <lennart@...ttering.net>
> Cc: Kay Sievers <kay@...y.org>
> Signed-off-by: Werner Fink <werner@...e.de>
> Signed-off-by: Hannes Reinecke <hare@...e.de>
> ---
>  drivers/tty/tty_io.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> index c74a00a..17db8ca 100644
> --- a/drivers/tty/tty_io.c
> +++ b/drivers/tty/tty_io.c
> @@ -3545,9 +3545,19 @@ static ssize_t show_cons_active(struct device *dev,
>                 if (i >= ARRAY_SIZE(cs))
>                         break;
>         }
> -       while (i--)
> +       while (i--) {
> +               const struct tty_driver *driver;
> +               const char *name = cs[i]->name;
> +               int index = cs[i]->index;
> +
> +               driver = cs[i]->device(cs[i], &index);
> +               if (driver) {
> +                       index += driver->name_base;
> +                       name = driver->name;
> +               }
>                 count += sprintf(buf + count, "%s%d%c",
> -                                cs[i]->name, cs[i]->index, i ? ' ':'\n');
> +                                name, index, i ? ' ':'\n');
> +       }

Nice catch and indeed, systemd already relies on these names to be
identical to their char-dev name. Fortunately, VTs and most serial
devices register the console with the same name as the TTY, so we're
fine.
Two minor nitpicks:
1) Could you use tty_line_name() instead of sprintf()? It's in the
same file and avoids duplicating the name_base logic.
2) Does it make sense to print the console-name if ->device() returns
NULL? Seems weird if we print console-names and tty-names in the same
attribute. It's unlikely that it causes problems, but there might be
conflicts.

Thanks
David

>         console_unlock();
>
>         return count;
> --
> 1.7.12.4
>
> _______________________________________________
> systemd-devel mailing list
> systemd-devel@...ts.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
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/

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