linux-kernel - Re: [PATCH 2.6.32 19/38] [PATCH 19/38] pagemap: hide physical addresses from non-privileged users

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Message-ID: <20151130121334.GA2445@1wt.eu>
Date:	Mon, 30 Nov 2015 13:13:34 +0100
From:	Willy Tarreau <w@....eu>
To:	Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc:	Ben Hutchings <ben@...adent.org.uk>, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Mark Williamson <mwilliamson@...o-software.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 2.6.32 19/38] [PATCH 19/38] pagemap: hide physical addresses from non-privileged users

On Mon, Nov 30, 2015 at 02:49:59PM +0300, Konstantin Khlebnikov wrote:
> On 30.11.2015 14:30, Willy Tarreau wrote:
> >+	/* do not disclose physical addresses: attack vector */
> >+	pm.show_pfn = !cap_capable(current, file->f_cred, CAP_SYS_ADMIN, 
> >SECURITY_CAP_AUDIT);
> >+
> 
> At first sight this is confusing... but correct. It really returns zero
> for success, unlike to new file_ns_capable which returns bool true.

Yes, it trapped me as well, the first attempt I made only allowed non-root
to read the pagemap!

> The rest looks good too.

OK thank you.

Willy

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