From: Ian Campbell <ijc@hellion.org.uk>
To: Greg KH <gregkh@linuxfoundation.org>,
kernel-hardening@lists.openwall.com,
Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: linux-kernel@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
William Roberts <william.c.roberts@intel.com>,
Chris Fries <cfries@google.com>,
Dave Weinstein <olorin@google.com>
Subject: Re: [kernel-hardening] [RFC 3/6] lib: vsprintf: physical address kernel pointer filtering options
Date: Sat, 06 May 2017 11:48:36 +0100 [thread overview]
Message-ID: <1494067716.4633.8.camel@hellion.org.uk> (raw)
In-Reply-To: <20170506040720.GD32707@kroah.com>
On Fri, 2017-05-05 at 21:07 -0700, Greg KH wrote:
> From: Dave Weinstein <olorin@google.com>
>
> Add the kptr_restrict setting of 4 which results in %pa and
> %p[rR] values being replaced by zeros.
Given that '%pa' is:
* - 'a[pd]' For address types [p] phys_addr_t, [d] dma_addr_t and derivatives
* (default assumed to be phys_addr_t, passed by reference)
what is the thread model which hiding physical addresses from attackers
protects against? I can see why virtual addresses would be obviously
dangerous but physical addresses seem less obvious and I didn't see it
spelled out in any of the commit messages or added comments in the
thread.
I think a comment somewhere would be useful for people who are trying
to decide if they should use %pa vs %paP etc.
Ian.
next prev parent reply other threads:[~2017-05-06 10:49 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-06 4:06 [RFC 00/06] printk: add more new kernel pointer filter options Greg KH
2017-05-06 4:06 ` [RFC 1/6] lib: vsprintf: additional kernel pointer filtering options Greg KH
2017-05-16 11:58 ` Petr Mladek
2017-05-18 14:12 ` Greg KH
2017-05-06 4:07 ` [RFC 2/6] lib: vsprintf: whitelist stack traces Greg KH
2017-05-06 4:07 ` [RFC 3/6] lib: vsprintf: physical address kernel pointer filtering options Greg KH
2017-05-06 10:48 ` Ian Campbell [this message]
2017-05-06 4:07 ` [RFC 4/6] lib: vsprintf: default kptr_restrict to the maximum value Greg KH
2017-05-06 4:07 ` [RFC 5/6] lib: vsprintf: Add "%paP", "%padP" options Greg KH
2017-05-06 4:42 ` Joe Perches
2017-05-06 5:00 ` Greg KH
2017-05-16 14:41 ` Petr Mladek
2017-05-18 14:12 ` Greg KH
2017-05-06 4:07 ` [RFC 6/6] drivers: uio: Un-restrict sysfs pointers for UIO Greg KH
2017-05-11 1:37 ` [RFC 00/06] printk: add more new kernel pointer filter options Sergey Senozhatsky
2017-05-16 21:36 ` Roberts, William C
2017-05-18 14:13 ` Greg KH
2017-05-19 20:25 ` Roberts, William C
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