linux-kernel - Re: [kernel-hardening] Re: [PATCH] proc: restrict access to /proc/interrupts

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Message-ID: <20111108132326.214bcaf8@lxorguk.ukuu.org.uk>
Date:	Tue, 8 Nov 2011 13:23:26 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Vasiliy Kulikov <segoon@...nwall.com>
Cc:	Greg KH <greg@...ah.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Eric Paris <eparis@...isplace.org>,
	kernel-hardening@...ts.openwall.com, Valdis.Kletnieks@...edu,
	linux-kernel@...r.kernel.org,
	Alexey Dobriyan <adobriyan@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-security-module@...r.kernel.org
Subject: Re: [kernel-hardening] Re: [PATCH] proc: restrict access to
 /proc/interrupts

> /proc/{interrupts,stat} are 0444, which may be used by local attacker to
> learn statistical information about user's keystrokes, including the
> passwords.

So the distro can chmod it 0400

> /dev/pts/* and /dev/tty* leak the same timing information in inode's
> atime and mtime.

That one is trickier. I don't think it is a real leak because the last
update timing info is in seconds granularity so is pretty useless for
that. The atime/mtime behaviour is however required ABI and used by
applications so can't simply go away.

> Do we want to restrict permissions of interrupts/stat and remove atime
> and mtime from ttys and relax these permissions when revoke() is introduced?

revoke makes no difference I can see to either of these, they appear to
be a completely unrelated discussion.
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