From: Thomas Garnier <thgarnie@google.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: "Russell King - ARM Linux" <linux@armlinux.org.uk>,
"Arnd Bergmann" <arnd@arndb.de>,
"David Howells" <dhowells@redhat.com>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Dave Hansen" <dave.hansen@intel.com>,
"René Nyffenegger" <mail@renenyffenegger.ch>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Kees Cook" <keescook@chromium.org>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
"Petr Mladek" <pmladek@suse.com>,
"Andy Lutomirski" <luto@kernel.org>,
"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
"Nicolas Pitre" <nicolas.pitre@linaro.org>,
"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>,
"Sergey Senozhatsky" <sergey.senozhatsky@gmail.com>,
"Helge Deller" <deller@gmx.de>, "Rik van Riel" <riel@redhat.com>,
"Ingo Molnar" <mingo@kernel.org>,
"John Stultz" <john.stultz@linaro.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Oleg Nesterov" <oleg@redhat.com>,
"Stanislav Kinsburskiy" <skinsbursky@virt>
Subject: Re: [PATCH v1 1/4] syscalls: Restore address limit after a syscall
Date: Wed, 8 Mar 2017 14:27:18 -0800 [thread overview]
Message-ID: <CAJcbSZG21d3=1w5eiWtxUF4ooDiGPZc7wOExPsGiB3D3wTUFLQ@mail.gmail.com> (raw)
In-Reply-To: <CALCETrX1RpjZxdo1aauQa8hGQPO1Dzn5gU6NoT1CvSKo8ea1uQ@mail.gmail.com>
That make sense. I will optimize each architecture to not require a call.
On Wed, Mar 8, 2017 at 2:20 PM, Andy Lutomirski <luto@amacapital.net> wrote:
> On Wed, Mar 8, 2017 at 1:58 PM, Russell King - ARM Linux
> <linux@armlinux.org.uk> wrote:
>> On Wed, Mar 08, 2017 at 01:38:41PM -0800, Thomas Garnier wrote:
>>> This patch prevents a syscall to modify the address limit of the
>>> caller. The address limit is kept by the syscall wrapper and restored
>>> just after the syscall ends.
>>
>> I would much rather architectures were given the opportunity to code up
>> checks like this efficiently (iow, inline in the exit path assembly),
>> rather than having to unconditionally call an additional function on
>> every syscall, with its register saving overheads.
>>
>
> Me too. I think the two config choices should be:
>
> (a) BUG_ON(!segment_eq(...));
>
> (b) No generic check at all -- arch code will handle it
>
> --Andy
--
Thomas
prev parent reply other threads:[~2017-03-08 22:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-08 21:38 [PATCH v1 1/4] syscalls: Restore address limit after a syscall Thomas Garnier
2017-03-08 21:38 ` [PATCH v1 2/4] x86/syscalls: Specific usage of verify_pre_usermode_state Thomas Garnier
2017-03-08 21:38 ` [PATCH v1 3/4] arm/syscalls: " Thomas Garnier
2017-03-08 21:49 ` Russell King - ARM Linux
2017-03-08 22:05 ` Nicolas Pitre
2017-03-08 22:33 ` Thomas Garnier
2017-03-08 21:38 ` [PATCH v1 4/4] arm64/syscalls: " Thomas Garnier
2017-03-08 21:57 ` [PATCH v1 1/4] syscalls: Restore address limit after a syscall Kees Cook
2017-03-09 1:13 ` Thomas Garnier
2017-03-08 21:58 ` Russell King - ARM Linux
2017-03-08 22:20 ` Andy Lutomirski
2017-03-08 22:27 ` Thomas Garnier [this message]
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