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From: Dave Hansen <dave.hansen@linux.intel.com>
To: Andy Lutomirski <luto@amacapital.net>, "H. Peter Anvin" <hpa@zytor.com>
Cc: Oleg Nesterov <oleg@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
	Brian Gerst <brgerst@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: Rethinking sigcontext's xfeatures slightly for PKRU's benefit?
Date: Fri, 18 Dec 2015 10:42:55 -0800	[thread overview]
Message-ID: <567453AF.5060808@linux.intel.com> (raw)
In-Reply-To: <CALCETrU28FoOwR+n8U0Qtt20=ZW6rgc3=M8X4G0QMt1_ZVHY7Q@mail.gmail.com>

On 12/18/2015 08:04 AM, Andy Lutomirski wrote:
> 1b. If the app malfunctions such that RSP points to pmem, the kernel
> MUST NOT clobber the pmem space.  I think that this basically mandates
> that PKRU needs to have some safe state (i.e. definitely not the init
> state) on signal delivery: the kernel is going to write a signal frame
> at the address identified by RSP, and that address is in pmem, so
> those writes need to fail.

The kernel is writing the signal frame using normal old copy_to_user().
 Those are writing through mappings with _PAGE_USER set and should be
subject to the PKRU state of the thread before the signal started to be
delivered.

We don't do the fpu__clear() until after this copy, so I think pkeys
enforcement is being done properly for this today.

  parent reply	other threads:[~2015-12-18 18:42 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-18  1:48 Rethinking sigcontext's xfeatures slightly for PKRU's benefit? Andy Lutomirski
2015-12-18  2:13 ` Dave Hansen
2015-12-18  2:32   ` Andy Lutomirski
2015-12-18  2:52     ` Dave Hansen
2015-12-18  5:29       ` Andy Lutomirski
2015-12-18  6:43         ` H. Peter Anvin
2015-12-18 16:04           ` Andy Lutomirski
2015-12-18 16:56             ` Dave Hansen
2015-12-18 18:42             ` Dave Hansen [this message]
2015-12-18 19:21               ` Andy Lutomirski
2015-12-18 20:07                 ` Dave Hansen
2015-12-18 20:28                   ` Andy Lutomirski
2015-12-18 20:37                   ` Linus Torvalds
2015-12-18 20:49                     ` Andy Lutomirski
2015-12-18 20:58                       ` H. Peter Anvin
2015-12-18 21:02                         ` Andy Lutomirski
2015-12-18 21:08                           ` Dave Hansen
2015-12-18 21:04                       ` Linus Torvalds
2015-12-18 21:09                         ` Linus Torvalds
2015-12-18 21:12                         ` Dave Hansen
2015-12-18 21:45                           ` Linus Torvalds
2015-12-18 22:28                             ` Andy Lutomirski
2015-12-18 23:08                               ` Linus Torvalds
2015-12-18 23:16                                 ` Andy Lutomirski
2015-12-18 23:20                                   ` Linus Torvalds
2015-12-21 17:04                                   ` Dave Hansen
2015-12-21 22:52                                     ` Andy Lutomirski
2015-12-21 23:00                                       ` Dave Hansen
2015-12-21 23:02                                         ` Andy Lutomirski
2015-12-21 23:05                                           ` Dave Hansen
2015-12-21 23:04                               ` Dave Hansen
2015-12-21 23:07                                 ` Andy Lutomirski
2016-06-30 17:36                                   ` Andy Lutomirski
2016-06-30 21:25                                     ` Dave Hansen
2016-07-01 16:30                                       ` Andy Lutomirski
2015-12-29 23:48                             ` Dave Hansen
2015-12-18  8:32         ` Ingo Molnar
2015-12-18  8:59 ` Christoph Hellwig
2015-12-18 12:57   ` Borislav Petkov
2016-01-12 13:38     ` Ingo Molnar
2016-01-12 13:42       ` Christoph Hellwig
2016-01-13 10:48         ` Ingo Molnar

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