linux-kernel - Re: Question on "uaccess: Add strict non-pagefault kernel-space read function"

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Message-ID: <20200407093357.GA24309@infradead.org>
Date:   Tue, 7 Apr 2020 02:33:57 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Masami Hiramatsu <mhiramat@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
        bgregg@...flix.com
Subject: Re: Question on "uaccess: Add strict non-pagefault kernel-space read
 function"

On Tue, Apr 07, 2020 at 11:03:23AM +0200, Daniel Borkmann wrote:
> 
> ... where archs with non-overlapping user and kernel address range would
> only end up having to implementing kernel_range_ok() check. Or, instead of
> a generic kernel_range_ok() this could perhaps be more probing-specific as
> in probe_kernel_range_ok() where this would then also cover the special
> cases we seem to have in parisc and um. Then, this would allow to get rid
> of all the __weak aliasing as well which may just be confusing. I could look
> into coming up with something along these lines. Thoughts?

FYI, this is what I cooked up a few days ago:

http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/maccess-fixups

Still misses the final work to switch probe_kernel_read to be the
strict version.  Any good naming suggestion for the non-strict one?