From: David Laight <David.Laight@ACULAB.COM>
To: "'Madhavan T. Venkataraman'" <madvenka@linux.microsoft.com>,
"Andy Lutomirski" <luto@kernel.org>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>,
Linux API <linux-api@vger.kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
linux-integrity <linux-integrity@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"LSM List" <linux-security-module@vger.kernel.org>,
Oleg Nesterov <oleg@redhat.com>, X86 ML <x86@kernel.org>
Subject: RE: [PATCH v1 0/4] [RFC] Implement Trampoline File Descriptor
Date: Mon, 3 Aug 2020 08:23:03 +0000 [thread overview]
Message-ID: <a5fb2778a86f45b58ef5dd35228d950b@AcuMS.aculab.com> (raw)
In-Reply-To: <3b916198-3a98-bd19-9a1c-f2d8d44febe8@linux.microsoft.com>
From: Madhavan T. Venkataraman
> Sent: 02 August 2020 19:55
> To: Andy Lutomirski <luto@kernel.org>
> Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>; Linux API <linux-api@vger.kernel.org>;
> linux-arm-kernel <linux-arm-kernel@lists.infradead.org>; Linux FS Devel <linux-
> fsdevel@vger.kernel.org>; linux-integrity <linux-integrity@vger.kernel.org>; LKML <linux-
> kernel@vger.kernel.org>; LSM List <linux-security-module@vger.kernel.org>; Oleg Nesterov
> <oleg@redhat.com>; X86 ML <x86@kernel.org>
> Subject: Re: [PATCH v1 0/4] [RFC] Implement Trampoline File Descriptor
>
> More responses inline..
>
> On 7/28/20 12:31 PM, Andy Lutomirski wrote:
> >> On Jul 28, 2020, at 6:11 AM, madvenka@linux.microsoft.com wrote:
> >>
> >> From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>
> >>
> >
> > 2. Use existing kernel functionality. Raise a signal, modify the
> > state, and return from the signal. This is very flexible and may not
> > be all that much slower than trampfd.
>
> Let me understand this. You are saying that the trampoline code
> would raise a signal and, in the signal handler, set up the context
> so that when the signal handler returns, we end up in the target
> function with the context correctly set up. And, this trampoline code
> can be generated statically at build time so that there are no
> security issues using it.
>
> Have I understood your suggestion correctly?
I was thinking that you'd just let the 'not executable' page fault
signal happen (SIGSEGV?) when the code jumps to on-stack trampoline
is executed.
The user signal handler can then decode the faulting instruction
and, if it matches the expected on-stack trampoline, modify the
saved registers before returning from the signal.
No kernel changes and all you need to add to the program is
an architecture-dependant signal handler.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-08-03 8:23 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <aefc85852ea518982e74b233e11e16d2e707bc32>
2020-07-28 13:10 ` [PATCH v1 0/4] [RFC] Implement Trampoline File Descriptor madvenka
2020-07-28 13:10 ` [PATCH v1 1/4] [RFC] fs/trampfd: Implement the trampoline file descriptor API madvenka
2020-07-28 14:50 ` Oleg Nesterov
2020-07-28 14:58 ` Madhavan T. Venkataraman
2020-07-28 16:06 ` Oleg Nesterov
2020-07-28 13:10 ` [PATCH v1 2/4] [RFC] x86/trampfd: Provide support for the trampoline file descriptor madvenka
2020-07-30 9:06 ` Greg KH
2020-07-30 14:25 ` Madhavan T. Venkataraman
2020-07-28 13:10 ` [PATCH v1 3/4] [RFC] arm64/trampfd: " madvenka
2020-07-28 13:10 ` [PATCH v1 4/4] [RFC] arm/trampfd: " madvenka
2020-07-28 15:13 ` [PATCH v1 0/4] [RFC] Implement Trampoline File Descriptor David Laight
2020-07-28 16:32 ` Madhavan T. Venkataraman
2020-07-28 17:16 ` Andy Lutomirski
2020-07-28 18:52 ` Madhavan T. Venkataraman
2020-07-29 8:36 ` David Laight
2020-07-29 17:55 ` Madhavan T. Venkataraman
[not found] ` <81d744c0-923e-35ad-6063-8b186f6a153c@linux.microsoft.com>
2020-07-29 5:16 ` Andy Lutomirski
2020-07-28 16:05 ` Casey Schaufler
2020-07-28 16:49 ` Madhavan T. Venkataraman
2020-07-28 17:05 ` James Morris
2020-07-28 17:08 ` Madhavan T. Venkataraman
2020-07-28 17:31 ` Andy Lutomirski
2020-07-28 19:01 ` Madhavan T. Venkataraman
2020-07-29 13:29 ` Florian Weimer
2020-07-30 13:09 ` David Laight
2020-08-02 11:56 ` Pavel Machek
2020-08-03 8:08 ` David Laight
2020-08-03 15:57 ` Madhavan T. Venkataraman
2020-07-30 14:42 ` Madhavan T. Venkataraman
[not found] ` <6540b4b7-3f70-adbf-c922-43886599713a@linux.microsoft.com>
2020-07-30 20:54 ` Andy Lutomirski
2020-07-31 17:13 ` Madhavan T. Venkataraman
2020-07-31 18:31 ` Mark Rutland
2020-08-03 8:27 ` David Laight
2020-08-03 16:03 ` Madhavan T. Venkataraman
2020-08-03 16:57 ` David Laight
2020-08-03 17:00 ` Madhavan T. Venkataraman
2020-08-03 17:58 ` Madhavan T. Venkataraman
2020-08-04 13:55 ` Mark Rutland
2020-08-04 14:33 ` David Laight
2020-08-04 14:44 ` David Laight
2020-08-04 14:48 ` Madhavan T. Venkataraman
2020-08-04 15:46 ` Madhavan T. Venkataraman
2020-08-02 13:57 ` Florian Weimer
2020-08-02 18:54 ` Madhavan T. Venkataraman
2020-08-02 20:00 ` Andy Lutomirski
2020-08-02 22:58 ` Madhavan T. Venkataraman
2020-08-03 18:36 ` Madhavan T. Venkataraman
2020-08-10 17:34 ` Madhavan T. Venkataraman
2020-08-11 21:12 ` Madhavan T. Venkataraman
2020-08-03 8:23 ` David Laight [this message]
2020-08-03 15:59 ` Madhavan T. Venkataraman
2020-07-31 18:09 ` Mark Rutland
2020-07-31 20:08 ` Madhavan T. Venkataraman
2020-08-03 16:57 ` Madhavan T. Venkataraman
2020-08-04 14:30 ` Mark Rutland
2020-08-06 17:26 ` Madhavan T. Venkataraman
2020-08-08 22:17 ` Pavel Machek
2020-08-11 12:41 ` Madhavan T. Venkataraman
2020-08-11 13:08 ` Pavel Machek
2020-08-11 15:54 ` Madhavan T. Venkataraman
2020-08-12 10:06 ` Mark Rutland
2020-08-12 18:47 ` Madhavan T. Venkataraman
2020-08-19 18:53 ` Mickaël Salaün
2020-09-01 15:42 ` Mark Rutland
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