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 = ¤t->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.
next prev 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
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