Re: [PATCH 3.15] MIPS: Add new AUDIT_ARCH token for the N32 ABI on MIPS64

[Andy Lutomirski]

On Wed, May 21, 2014 at 1:59 PM, Paul Moore <pmoore@xxxxxxxxxx> wrote:
> On Monday, May 12, 2014 02:53:05 PM Paul Moore wrote:
>> On Tuesday, April 22, 2014 03:40:36 PM Markos Chandras wrote:
>> > A MIPS64 kernel may support ELF files for all 3 MIPS ABIs
>> > (O32, N32, N64). Furthermore, the AUDIT_ARCH_MIPS{,EL}64 token
>> > does not provide enough information about the ABI for the 64-bit
>> > process. As a result of which, userland needs to use complex
>> > seccomp filters to decide whether a syscall belongs to the o32 or n32
>> > or n64 ABI. Therefore, a new arch token for MIPS64/n32 is added so it
>> > can be used by seccomp to explicitely set syscall filters for this ABI.
>> >
>> > Link: http://sourceforge.net/p/libseccomp/mailman/message/32239040/
>> > Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
>> > Cc: Eric Paris <eparis@xxxxxxxxxx>
>> > Cc: Paul Moore <pmoore@xxxxxxxxxx>
>> > Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
>> > Signed-off-by: Markos Chandras <markos.chandras@xxxxxxxxxx>
>> > ---
>> > Ralf, can we please have this in 3.15 (Assuming it's ACK'd)?
>> >
>> > Thanks a lot!
>> > ---
>> >
>> >  arch/mips/include/asm/syscall.h |  2 ++
>> >  include/uapi/linux/audit.h      | 12 ++++++++++++
>> >  2 files changed, 14 insertions(+)
>>
>> [NOTE: Adding lkml to the To line to hopefully spur discussion/acceptance as
>> this *really* should be in 3.15]
>>
>> I'm re-replying to this patch and adding lkml to the To line because I
>> believe it is very important we get this patch into 3.15.  For those who
>> don't follow the MIPS architecture very closely, the upcoming 3.15 is the
>> first release to include support for seccomp filters, the latest generation
>> of syscall filtering which used a BPF based filter language.  For reason
>> that are easy to understand, the syscall filters are ABI specific (e.g.
>> syscall tables, word length, endianness) and those generating syscall
>> filters in userspace (e.g. libseccomp) need to take great care to ensure
>> that the generated filters take the ABI into account and fail safely in the
>> case where a different ABI is used (e.g. x86, x86_64, x32).
>>
>> The patch below corrects, what is IMHO, an omission in the original MIPS
>> seccomp filter patch, allowing userspace to easily separate MIPS and MIPS64.
>> Without this patch we will be forced to handle MIPS/MIPS64 like we handle
>> x86_64/x32 which is a royal pain and not something I want to have deal with
>> again.
>>
>> Further, while I don't want to speak for the audit folks, it is my
>> understanding that they want this patch for similar reasons.
>>
>> Please merge this patch for 3.15 or at least provide some feedback as to why
>> this isn't a viable solution for upstream.  Once 3.15 ships, fixing this
>> will require breaking the MIPS ABI which isn't something any of us want.
>>
>> Thanks,
>> -Paul
>
> *Bump*
>
> I don't know what else needs to be done to get some action on this and we're
> running out of time for 3.15.

Reply to Linus' next -rc email.

--Andy
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