linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Andy Lutomirski <luto@kernel.org>
To: Gabriel Krisman Bertazi <krisman@collabora.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	kernel@collabora.com, Matthew Wilcox <willy@infradead.org>,
	Andrew Lutomirski <luto@kernel.org>,
	Paul Gofman <gofmanp@gmail.com>,
	Kees Cook <keescook@chromium.org>,
	"open list:KERNEL SELFTEST FRAMEWORK" 
	<linux-kselftest@vger.kernel.org>, Shuah Khan <shuah@kernel.org>
Subject: Re: [PATCH v4 1/2] kernel: Implement selective syscall userspace redirection
Date: Thu, 16 Jul 2020 17:20:02 -0700	[thread overview]
Message-ID: <CALCETrWdCN5KsRUkrb8VoYGRBhy71P-MAHGWhuJ5y4Z3vByyvg@mail.gmail.com> (raw)
In-Reply-To: <20200716193141.4068476-2-krisman@collabora.com>

On Thu, Jul 16, 2020 at 12:31 PM Gabriel Krisman Bertazi
<krisman@collabora.com> wrote:
>

This is quite nice.  I have a few comments, though:

You mentioned rt_sigreturn().  Should this automatically exempt the
kernel-provided signal restorer on architectures (e.g. x86_32) that
provide one?

The amount of syscall entry wiring that arches need to do is IMO
already a bit out of hand.  Should we instead rename TIF_SECCOMP to
TIF_SYSCALL_INTERCEPTION and have one generic callback that handles
seccomp and this new thing?

> +int do_syscall_user_dispatch(struct pt_regs *regs)
> +{
> +       struct syscall_user_dispatch *sd = &current->syscall_dispatch;
> +       unsigned long ip = instruction_pointer(regs);
> +       char state;
> +
> +       if (likely(ip >= sd->dispatcher_start && ip <= sd->dispatcher_end))
> +               return 0;
> +
> +       if (likely(sd->selector)) {
> +               if (unlikely(__get_user(state, sd->selector)))
> +                       do_exit(SIGSEGV);
> +
> +               if (likely(state == 0))
> +                       return 0;
> +
> +               if (state != 1)
> +                       do_exit(SIGSEGV);

This seems a bit extreme and hard to debug if it ever happens.

  parent reply	other threads:[~2020-07-17  0:20 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-16 19:31 [PATCH v4 0/2] Syscall User Redirection Gabriel Krisman Bertazi
2020-07-16 19:31 ` [PATCH v4 1/2] kernel: Implement selective syscall userspace redirection Gabriel Krisman Bertazi
2020-07-16 21:06   ` Matthew Wilcox
2020-07-16 21:26     ` Kees Cook
2020-07-17  0:20   ` Andy Lutomirski [this message]
2020-07-17  2:15     ` Gabriel Krisman Bertazi
2020-07-17  4:48       ` Andy Lutomirski
2020-07-21 12:06         ` Mark Rutland
2020-07-20  9:23     ` Thomas Gleixner
2020-07-20  9:44       ` Will Deacon
2020-07-20 10:08   ` Thomas Gleixner
2020-07-20 13:46     ` Gabriel Krisman Bertazi
2020-07-16 19:31 ` [PATCH v4 2/2] selftests: Add kselftest for syscall user dispatch Gabriel Krisman Bertazi
2020-07-16 20:04 ` [PATCH v4 0/2] Syscall User Redirection Kees Cook
2020-07-16 20:22   ` Christian Brauner
2020-07-16 20:25     ` Kees Cook
2020-07-16 20:29       ` Christian Brauner
2020-07-16 20:30         ` Gabriel Krisman Bertazi
2020-07-16 21:06           ` Carlos O'Donell
2020-08-02 12:01 ` Pavel Machek
2020-08-04 14:26   ` Gabriel Krisman Bertazi

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=CALCETrWdCN5KsRUkrb8VoYGRBhy71P-MAHGWhuJ5y4Z3vByyvg@mail.gmail.com \
    --to=luto@kernel.org \
    --cc=gofmanp@gmail.com \
    --cc=keescook@chromium.org \
    --cc=kernel@collabora.com \
    --cc=krisman@collabora.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=shuah@kernel.org \
    --cc=tglx@linutronix.de \
    --cc=willy@infradead.org \
    --subject='Re: [PATCH v4 1/2] kernel: Implement selective syscall userspace redirection' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).