Re: [PATCH] mm/nommu.c: Fix improperly call of security API in mmap

From: Eric Paris
Date: Fri Oct 16 2009 - 11:23:48 EST


On Fri, 2009-10-16 at 16:14 +0100, David Howells wrote:
> Eric Paris <eparis@xxxxxxxxxxxxxx> wrote:
>
> > I really don't like seeing such irrelevant (that's not the right word,
> > but I can't think what is) ifdefs creeping down into the security
> > layer as LSM authors are likely to mess them up in the future. I'd
> > probably rather see the addr_only argument changed into a flags field.
> > One for addr_only and one flag for not_addr. The nommu case could
> > just set the not_addr flag and it's obvious how the LSMs (or
> > capabilities if !CONFIG_SECURITY) should handle it, also works if some
> > other future need arises...
>
> A better way still, might be to deny the possibility of CONFIG_SECURITY if
> CONFIG_MMU=n. After all, security is sort of pointless when a userspace
> program can just edit the kernel at a whim.

That would still call cap_file_mmap() and wouldn't solve your problem.

-Eric

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