linux-kernel - Re: [PATCH v3 0/8] Two-phase seccomp and x86 tracing changes

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Message-ID: <CALCETrVwqDeRbFOw=k_OhQZ4V6Pn5v3t8ODw75UuE7HKPFz=Sw@mail.gmail.com>
Date:	Wed, 23 Jul 2014 12:20:18 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Kees Cook <keescook@...omium.org>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Will Drewry <wad@...omium.org>,
	Oleg Nesterov <oleg@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Linux MIPS Mailing List <linux-mips@...ux-mips.org>,
	linux-arch <linux-arch@...r.kernel.org>,
	linux-security-module <linux-security-module@...r.kernel.org>,
	Alexei Starovoitov <ast@...mgrid.com>
Subject: Re: [PATCH v3 0/8] Two-phase seccomp and x86 tracing changes

On Tue, Jul 22, 2014 at 12:37 PM, Kees Cook <keescook@...omium.org> wrote:
> On Mon, Jul 21, 2014 at 6:49 PM, Andy Lutomirski <luto@...capital.net> wrote:
>> [applies on jmorris's security-next tree]
>>
>> This is both a cleanup and a speedup.  It reduces overhead due to
>> installing a trivial seccomp filter by 87%.  The speedup comes from
>> avoiding the full syscall tracing mechanism for filters that don't
>> return SECCOMP_RET_TRACE.
>>
>> This series works by splitting the seccomp hooks into two phases.
>> The first phase evaluates the filter; it can skip syscalls, allow
>> them, kill the calling task, or pass a u32 to the second phase.  The
>> second phase requires a full tracing context, and it sends ptrace
>> events if necessary.
>>
>> Once this is done, I implemented a similar split for the x86 syscall
>> entry work.  The C callback is invoked in two phases: the first has
>> only a partial frame, and it can request phase 2 processing with a
>> full frame.
>>
>> Finally, I switch the 64-bit system_call code to use the new split
>> entry work.  This is a net deletion of assembly code: it replaces
>> all of the audit entry muck.
>>
>> In the process, I fixed some bugs.
>>
>> If this is acceptable, someone can do the same tweak for the
>> ia32entry and entry_32 code.
>>
>> This passes all seccomp tests that I know of.  Now that it's properly
>> rebased, even the previously expected failures are gone.
>>
>> Kees, if you like this version, can you create a branch with patches
>> 1-4?  I think that the rest should go into tip/x86 once everyone's happy
>> with it.
>>
>> Changes from v2:
>>  - Fixed 32-bit x86 build (and the tests pass).
>>  - Put the doc patch where it belongs.
>
> Thanks! This looks good to me. I'll add it to my tree.
>
> Peter, how do you feel about this series? Do the x86 changes look good to you?
>

It looks like patches 1-4 have landed here:

https://git.kernel.org/cgit/linux/kernel/git/kees/linux.git/log/?h=seccomp/fastpath

hpa, what's the route forward for the x86 part?

--Andy
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