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From: Ingo Molnar <mingo@kernel.org>
To: "Ren, Qiaowei" <qiaowei.ren@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "x86@kernel.org" <x86@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v3 3/4] x86, mpx: add prctl commands PR_MPX_INIT, PR_MPX_RELEASE
Date: Sun, 26 Jan 2014 16:14:22 +0100	[thread overview]
Message-ID: <20140126151422.GA5386@gmail.com> (raw)
In-Reply-To: <9E0BE1322F2F2246BD820DA9FC397ADE014F22A8@SHSMSX102.ccr.corp.intel.com>


* Ren, Qiaowei <qiaowei.ren@intel.com> wrote:

> The size of one bound table is 4M bytes for 64bit, and 16K bytes for 
> 32bit. It can not be accessed by user-space, and it will be accessed 
> automatically by hardware.

So, here's the bound-table allocation AFAICS:

+static bool allocate_bt(unsigned long bd_entry)
+{
+       unsigned long bt_size = 1UL << (MPX_L2_BITS+MPX_L2_SHIFT);
+       unsigned long bt_addr, old_val = 0;
+
+       bt_addr = sys_mmap_pgoff(0, bt_size, PROT_READ | PROT_WRITE,
+                       MAP_ANONYMOUS | MAP_PRIVATE | MAP_POPULATE, -1, 0);

What ensures that user-space cannot access (and in particular, modify) 
the pages at bt_addr? It's a read-write anonymous mapping AFAICS.

Thanks,

	Ingo

  reply	other threads:[~2014-01-26 15:14 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-01-26  9:08 [PATCH v3 0/4] Intel MPX support Qiaowei Ren
2014-01-26  8:19 ` Ingo Molnar
2014-01-26  8:20   ` Ren Qiaowei
2014-01-28  6:42     ` Ingo Molnar
2014-01-28  7:01       ` Ren Qiaowei
2014-01-28 18:26         ` H. Peter Anvin
2014-01-26  9:08 ` [PATCH v3 1/4] x86, mpx: add documentation on Intel MPX Qiaowei Ren
2014-01-26  3:06   ` Randy Dunlap
2014-01-26  3:15     ` Ren Qiaowei
2014-01-27 20:27   ` Andy Lutomirski
2014-01-28  3:40     ` Ren Qiaowei
2014-01-26  9:08 ` [PATCH v3 2/4] x86, mpx: hook #BR exception handler to allocate bound tables Qiaowei Ren
2014-01-27 20:36   ` Andy Lutomirski
2014-01-28  3:35     ` Ren Qiaowei
2014-01-28  5:21       ` Andy Lutomirski
2014-01-28  5:39         ` Ren Qiaowei
2014-01-28  6:42           ` Andy Lutomirski
2014-01-28  6:46             ` Ren Qiaowei
2014-01-26  9:08 ` [PATCH v3 3/4] x86, mpx: add prctl commands PR_MPX_INIT, PR_MPX_RELEASE Qiaowei Ren
2014-01-26  8:22   ` Ingo Molnar
2014-01-26  8:23     ` Ren Qiaowei
2014-01-26  8:39       ` Ingo Molnar
2014-01-26 11:37         ` Ren, Qiaowei
2014-01-27  1:50         ` H. Peter Anvin
2014-01-27  1:55           ` Ren Qiaowei
2014-01-27  2:10             ` H. Peter Anvin
2014-01-27  2:16               ` Ren Qiaowei
2014-01-27 21:54               ` Andy Lutomirski
2014-01-27 22:01                 ` H. Peter Anvin
2014-01-26  9:08   ` Ingo Molnar
2014-01-26 12:49     ` Ren, Qiaowei
2014-01-26 15:14       ` Ingo Molnar [this message]
2014-01-27  2:01         ` Ren Qiaowei
2014-01-27 20:59   ` Andy Lutomirski
2014-01-26  9:08 ` [PATCH v3 4/4] x86, mpx: extend siginfo structure to include bound violation information Qiaowei Ren
2014-01-26  4:22   ` David Rientjes
2014-01-26  4:39     ` Ren Qiaowei
2014-01-26 21:38       ` David Rientjes
2014-01-27  1:34         ` Ren Qiaowei
2014-01-27  1:53           ` H. Peter Anvin
2014-01-27  1:56             ` Ren Qiaowei
2014-01-27 21:58   ` Andy Lutomirski
2014-01-28  2:43     ` Ren Qiaowei

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