From: Linus Torvalds <torvalds@linux-foundation.org>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jirislaby@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Starke, Daniel" <daniel.starke@siemens.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-security-module <linux-security-module@vger.kernel.org>
Subject: Re: [PATCH v2] tty: n_gsm: restrict tty devices to attach
Date: Sat, 20 Apr 2024 10:34:17 -0700 [thread overview]
Message-ID: <CAHk-=wjEZvnn51dhhLqBKUd=cuFhbYA47_OyfUOPB-0zKToL7Q@mail.gmail.com> (raw)
In-Reply-To: <e696e720-0cd3-4505-8469-a94815b39467@I-love.SAKURA.ne.jp>
On Sat, 20 Apr 2024 at 04:12, Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
>
> Since n_gsm is designed to be used for serial port [1], reject attaching to
> virtual consoles and PTY devices, by checking tty's device major/minor
> numbers at gsmld_open().
If we really just want to restrict it to serial devices, then do
something like, this:
drivers/tty/n_gsm.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 4036566febcb..24425ef35b2b 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -3629,6 +3629,8 @@ static int gsmld_open(struct tty_struct *tty)
if (tty->ops->write == NULL)
return -EINVAL;
+ if (tty->ops->set_serial == NULL)
+ return -EINVAL;
/* Attach our ldisc data */
gsm = gsm_alloc_mux();
which at least matches the current (largely useless) pattern of
checking for a write function.
I think all real serial sub-drivers already have that 'set_serial()'
function, and if there are some that don't, we could just add a dummy
for them. No?
Alternatively, we could go the opposite way, and have some flag in the
line discipline that says "I can be a console", and just check that in
tty_set_ldisc() for the console.
That would probably be a good idea regardless, but likely requires more effort.
But this kind of random major number testing seems wrong. It's trying
to deal with the _symptoms_, not some deeper truth.
Linus
next prev parent reply other threads:[~2024-04-20 17:34 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-20 11:12 [PATCH v2] tty: n_gsm: restrict tty devices to attach Tetsuo Handa
2024-04-20 13:13 ` Greg Kroah-Hartman
2024-04-20 17:34 ` Linus Torvalds [this message]
2024-04-20 18:02 ` Linus Torvalds
2024-04-20 18:05 ` Linus Torvalds
2024-04-21 13:28 ` Tetsuo Handa
2024-04-21 16:04 ` Linus Torvalds
2024-04-21 17:18 ` Linus Torvalds
2024-04-23 15:26 ` Tetsuo Handa
2024-04-23 16:37 ` Linus Torvalds
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAHk-=wjEZvnn51dhhLqBKUd=cuFhbYA47_OyfUOPB-0zKToL7Q@mail.gmail.com' \
--to=torvalds@linux-foundation.org \
--cc=akpm@linux-foundation.org \
--cc=daniel.starke@siemens.com \
--cc=gregkh@linuxfoundation.org \
--cc=jirislaby@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=penguin-kernel@i-love.sakura.ne.jp \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.