Re: [PATCH 2/2] Revert "pstore: Honor dmesg_restrict sysctl on dmesg dumps"

From	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/2] Revert "pstore: Honor dmesg_restrict sysctl on dmesg dumps"
Date	2017-08-18 01:30 +0200
Message-ID	<ufCoF-3ms-1@gated-at.bofh.it> (permalink)
References	(1 earlier) <ud2pk-2qz-21@gated-at.bofh.it> <uf1p7-4gv-19@gated-at.bofh.it> <uf8Ah-mw-1@gated-at.bofh.it> <ufhNf-6dr-1@gated-at.bofh.it> <ufC5j-3fa-1@gated-at.bofh.it>
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Hello,

On (08/17/17 16:01), Kees Cook wrote:
> On Wed, Aug 16, 2017 at 6:29 PM, Sergey Senozhatsky
> <sergey.senozhatsky.work@gmail.com> wrote:
> > can we accidentally "leak" kernel pointers or some other critical
> > info? kptr_restrict requires CAP_SYSLOG and pstore read used to
> > require CAP_SYSLOG, but it seems that now we can bypass it by
> > letting "entirely unprivileged groups" to read pstore. is there
> > something to be concerned about (or at least mention it in the
> > commit messages)?
> 
> I can expand the commit message a bit more, sure.

that would be lovely. please do.

> There may be sensitive things in pstorefs, and it's up to a system builder
> to decide how they want to deal with that risk. Most users of pstore
> don't mount with update_ms=N so pstorefs contains (mostly) old
> addresses.

I see...

> Without this change, though, a builder can't give permissions to an
> unprivileged crash dump process without also giving it CAP_SYSLOG which
> has much MORE privilege that it would need (reading and wiping _current_
> dmesg, for example).

ok, the "CAP_SYSLOG and _current_ dmesg" point is surely interesting.
could you please also add this to the commit message?


FWIW, both patches

Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>

	-ss

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Re: [PATCH 2/2] Revert "pstore: Honor dmesg_restrict sysctl on dmesg  dumps" Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-08-16 10:00 +0200
  Re: [PATCH 2/2] Revert "pstore: Honor dmesg_restrict sysctl on dmesg dumps" Kees Cook <keescook@chromium.org> - 2017-08-16 17:40 +0200
    Re: [PATCH 2/2] Revert "pstore: Honor dmesg_restrict sysctl on dmesg  dumps" Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-08-17 03:30 +0200
      Re: [PATCH 2/2] Revert "pstore: Honor dmesg_restrict sysctl on dmesg dumps" Kees Cook <keescook@chromium.org> - 2017-08-18 01:10 +0200
        Re: [PATCH 2/2] Revert "pstore: Honor dmesg_restrict sysctl on dmesg  dumps" Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-08-18 01:30 +0200

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