linux-kernel - Re: [PATCH 2/3, V2] kernel: Move groups_sort to the caller of set

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Date:   Mon, 4 Dec 2017 17:00:51 -0200 (-02)
From:   Thiago Rafael Becker <thiago.becker@...il.com>
To:     "J. Bruce Fields" <bfields@...ldses.org>
cc:     Thiago Rafael Becker <thiago.becker@...il.com>,
        NeilBrown <neilb@...e.com>, linux-nfs@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3, V2] kernel: Move groups_sort to the caller of
 set_groups.



On Mon, 4 Dec 2017, J. Bruce Fields wrote:

> On Mon, Dec 04, 2017 at 01:39:37PM -0200, Thiago Rafael Becker wrote:
>>
>>
>> On Mon, 4 Dec 2017, NeilBrown wrote:
>>
>>> I think you need to add groups_sort() in a few more places.
>>> Almost anywhere that calls groups_alloc() should be considered.
>>> net/sunrpc/svcauth_unix.c, net/sunrpc/auth_gss/svcauth_gss.c,
>>> fs/nfsd/auth.c definitely need it.
>>
>> So are any other functions that modify group_info. OK, I think I'll
>> implement the type detection below as it helps detecting where these
>> situations are located.
>>
>> This may take some time to make sane. I wonder if we shouldn't
>> accept the first change suggested to fix the corruption detected in
>> auth.unix.gid while I work on a new set of patches. Also, that patch
>> doesn't change behavior of set_groups, and is easier to backport if
>> distros relying on older kernels need to do so and change behavior.
>> The first suggestion is undergoing tests, and so far we didn't
>> detect any new corruptions on auth.unix.gid.
>
> I'm a little confused--we can remedy the oversight Neil points out just
> by adding a few more group_sort()s, and that shouldn't be hard, right?
>
> I'd be OK with doing that first and then adding a code to enforce the
> sorting second.

Ok. Sending a new set. The set will cover all calls to group_alloc, after 
the function has ended filling the groups.

> --b.
>
>>
>>> Maybe it could be done with types.
>>
>> I changed the interfaces on groups_{alloc,sort} to check. There are
>> some extra changes needed in groups_from_user and others to make
>> this viable, but I like it and I'll try to make it happen.
>>
>>> Thanks,
>>> NeilBrown
>>>
>>
>> Thanks,
>> trbecker
>> --
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>