Re: [PATCH 00/31 v2] PTI support for x86_32

[Arnd Bergmann]

On Wed, Feb 21, 2018 at 11:26 AM, Lorenzo Colitti <lorenzo@xxxxxxxxxx> wrote:
> On Wed, Feb 14, 2018 at 5:54 PM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>> > > IPSEC doesn't work with a 64bit kernel and 32bit userspace right now.
>> > >
>> > > Back in 2015 someone started to work on that, and properly marked that
>> > > the kernel could not handle this with commit 74005991b78a ("xfrm: Do not
>> > > parse 32bits compiled xfrm netlink msg on 64bits host")
>> > >
>> > > This is starting to be hit by some Android systems that are moving
>> > > (yeah, slowly) to 4.4 :(
>> >
>> > Does anybody have test-programs/harnesses for this?
>>
>> Lorenzo (now on the To: line), is the one that I think is looking into
>> this, and should have some sort of test for it.  Lorenzo?
>
> Sorry for the late reply here. The issue is that the xfrm uapi structs
> don't specify padding at the end, so they're a different size on
> 32-bit and 64-bit archs. This by itself would be fine, as the kernel
> could just ignore the (lack of) padding. But some of these structs
> contain others (e.g., xfrm_userspi_info contains xfrm_usersa_info),
> and in that case the whole layout after the contained struct is
> different.

So this is x86 specific then and it already works correctly on all
other architectures (especially arm64 Android), right?

      Arnd