Re: [PATCH 2/3, V2] kernel: Move groups_sort to the caller of set_groups.

[J. Bruce Fields]

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.

--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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