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From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: Jann Horn <jannh@google.com>
Cc: the arch/x86 maintainers <x86@kernel.org>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	kernel list <linux-kernel@vger.kernel.org>,
	linux-doc@vger.kernel.org, Linux-MM <linux-mm@kvack.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Andy Lutomirski <luto@amacapital.net>,
	bsingharora@gmail.com, Cyrill Gorcunov <gorcunov@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Florian Weimer <fweimer@redhat.com>,
	hjl.tools@gmail.com, Jonathan Corbet <corbet@lwn.net>,
	keescook@chromiun.org, Mike Kravetz <mike.kravetz@oracle.com>,
	Nadav Amit <nadav.amit@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
	Peter Zijlstra <peterz@infradead.org>,
	ravi.v.shankar@intel.com, vedvyas.shanbhogue@intel.com
Subject: Re: [RFC PATCH v2 27/27] x86/cet: Add arch_prctl functions for CET
Date: Wed, 11 Jul 2018 13:55:44 -0700
Message-ID: <1531342544.15351.37.camel@intel.com> (raw)
In-Reply-To: <CAG48ez2cY1CPTTfDnV5yZyHVPXP787=fR1+G_D7tR5VYXdjFmQ@mail.gmail.com>

On Wed, 2018-07-11 at 12:45 -0700, Jann Horn wrote:
> On Tue, Jul 10, 2018 at 3:31 PM Yu-cheng Yu <yu-cheng.yu@intel.com>
> wrote:
> > 
> > 
> > arch_prctl(ARCH_CET_STATUS, unsigned long *addr)
> >     Return CET feature status.
> > 
> >     The parameter 'addr' is a pointer to a user buffer.
> >     On returning to the caller, the kernel fills the following
> >     information:
> > 
> >     *addr = SHSTK/IBT status
> >     *(addr + 1) = SHSTK base address
> >     *(addr + 2) = SHSTK size
> > 
> > arch_prctl(ARCH_CET_DISABLE, unsigned long features)
> >     Disable SHSTK and/or IBT specified in 'features'.  Return
> > -EPERM
> >     if CET is locked out.
> > 
> > arch_prctl(ARCH_CET_LOCK)
> >     Lock out CET feature.
> > 
> > arch_prctl(ARCH_CET_ALLOC_SHSTK, unsigned long *addr)
> >     Allocate a new SHSTK.
> > 
> >     The parameter 'addr' is a pointer to a user buffer and
> > indicates
> >     the desired SHSTK size to allocate.  On returning to the caller
> >     the buffer contains the address of the new SHSTK.
> > 
> > arch_prctl(ARCH_CET_LEGACY_BITMAP, unsigned long *addr)
> >     Allocate an IBT legacy code bitmap if the current task does not
> >     have one.
> > 
> >     The parameter 'addr' is a pointer to a user buffer.
> >     On returning to the caller, the kernel fills the following
> >     information:
> > 
> >     *addr = IBT bitmap base address
> >     *(addr + 1) = IBT bitmap size
> > 
> > Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
> > Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
> [...]
> > 
> > diff --git a/arch/x86/kernel/cet_prctl.c
> > b/arch/x86/kernel/cet_prctl.c
> > new file mode 100644
> > index 000000000000..86bb78ae656d
> > --- /dev/null
> > +++ b/arch/x86/kernel/cet_prctl.c
> > @@ -0,0 +1,141 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +
> > +#include <linux/errno.h>
> > +#include <linux/uaccess.h>
> > +#include <linux/prctl.h>
> > +#include <linux/compat.h>
> > +#include <asm/processor.h>
> > +#include <asm/prctl.h>
> > +#include <asm/elf.h>
> > +#include <asm/elf_property.h>
> > +#include <asm/cet.h>
> > +
> > +/* See Documentation/x86/intel_cet.txt. */
> > +
> > +static int handle_get_status(unsigned long arg2)
> > +{
> > +       unsigned int features = 0;
> > +       unsigned long shstk_base, shstk_size;
> > +
> > +       if (current->thread.cet.shstk_enabled)
> > +               features |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
> > +       if (current->thread.cet.ibt_enabled)
> > +               features |= GNU_PROPERTY_X86_FEATURE_1_IBT;
> > +
> > +       shstk_base = current->thread.cet.shstk_base;
> > +       shstk_size = current->thread.cet.shstk_size;
> > +
> > +       if (in_ia32_syscall()) {
> > +               unsigned int buf[3];
> > +
> > +               buf[0] = features;
> > +               buf[1] = (unsigned int)shstk_base;
> > +               buf[2] = (unsigned int)shstk_size;
> > +               return copy_to_user((unsigned int __user *)arg2,
> > buf,
> > +                                   sizeof(buf));
> > +       } else {
> > +               unsigned long buf[3];
> > +
> > +               buf[0] = (unsigned long)features;
> > +               buf[1] = shstk_base;
> > +               buf[2] = shstk_size;
> > +               return copy_to_user((unsigned long __user *)arg2,
> > buf,
> > +                                   sizeof(buf));
> > +       }
> Other places in the kernel (e.g. the BPF subsystem) just
> unconditionally use u64 instead of unsigned long to avoid having to
> switch between different sizes. I wonder whether that would make
> sense
> here?

Yes, that simplifies the code.  I will make that change.

Yu-cheng

      reply index

Thread overview: 123+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-10 22:26 [RFC PATCH v2 00/27] Control Flow Enforcement (CET) Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 01/27] x86/cpufeatures: Add CPUIDs for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 02/27] x86/fpu/xstate: Change some names to separate XSAVES system and user states Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 03/27] x86/fpu/xstate: Enable XSAVES system states Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 04/27] x86/fpu/xstate: Add XSAVES system states for shadow stack Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 05/27] Documentation/x86: Add CET description Yu-cheng Yu
2018-07-11  8:27   ` Pavel Machek
2018-07-11 15:25     ` Yu-cheng Yu
2018-07-11  9:57   ` Florian Weimer
2018-07-11 13:47     ` H.J. Lu
2018-07-11 14:53       ` Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 06/27] x86/cet: Control protection exception handler Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 07/27] x86/cet/shstk: Add Kconfig option for user-mode shadow stack Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 08/27] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2018-07-11  8:34   ` Peter Zijlstra
2018-07-11 16:15     ` Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 09/27] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 10/27] x86/mm: Introduce _PAGE_DIRTY_SW Yu-cheng Yu
2018-07-11  8:45   ` Peter Zijlstra
2018-07-11  9:21   ` Peter Zijlstra
2018-07-10 22:26 ` [RFC PATCH v2 11/27] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW Yu-cheng Yu
2018-07-10 22:44   ` Dave Hansen
2018-07-10 23:23     ` Nadav Amit
2018-07-10 23:52       ` Dave Hansen
2018-07-11  8:48     ` Peter Zijlstra
2018-07-10 22:26 ` [RFC PATCH v2 12/27] x86/mm: Shadow stack page fault error checking Yu-cheng Yu
2018-07-10 22:52   ` Dave Hansen
2018-07-11 17:28     ` Yu-cheng Yu
2018-07-10 23:24   ` Dave Hansen
2018-07-10 22:26 ` [RFC PATCH v2 13/27] mm: Handle shadow stack page fault Yu-cheng Yu
2018-07-10 23:06   ` Dave Hansen
2018-07-11  9:06     ` Peter Zijlstra
2018-08-14 21:28       ` Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 14/27] mm: Handle THP/HugeTLB " Yu-cheng Yu
2018-07-10 23:08   ` Dave Hansen
2018-07-11  9:10   ` Peter Zijlstra
2018-07-11 16:11     ` Yu-cheng Yu
2018-07-20 14:20   ` Dave Hansen
2018-07-20 14:58     ` Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 15/27] mm/mprotect: Prevent mprotect from changing shadow stack Yu-cheng Yu
2018-07-10 23:10   ` Dave Hansen
2018-07-11  9:12     ` Peter Zijlstra
2018-07-11 16:07       ` Yu-cheng Yu
2018-07-11 16:22         ` Dave Hansen
2018-07-10 22:26 ` [RFC PATCH v2 16/27] mm: Modify can_follow_write_pte/pmd for " Yu-cheng Yu
2018-07-10 23:37   ` Dave Hansen
2018-07-11 17:05     ` Yu-cheng Yu
2018-07-13 18:26       ` Dave Hansen
2018-07-17 23:03         ` Yu-cheng Yu
2018-07-17 23:11           ` Dave Hansen
2018-07-17 23:15           ` Dave Hansen
2018-07-18 20:14             ` Yu-cheng Yu
2018-07-18 21:45               ` Dave Hansen
2018-07-18 23:10                 ` Yu-cheng Yu
2018-07-19  0:06                   ` Dave Hansen
2018-07-19 17:06                     ` Yu-cheng Yu
2018-07-19 19:31                       ` Dave Hansen
2018-07-11  9:29   ` Peter Zijlstra
2018-07-17 23:00     ` Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 17/27] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2018-07-10 23:40   ` Dave Hansen
2018-07-11  9:34   ` Peter Zijlstra
2018-07-11 15:45     ` Yu-cheng Yu
2018-07-11  9:36   ` Peter Zijlstra
2018-07-11 21:10   ` Jann Horn
2018-07-11 21:34     ` Andy Lutomirski
2018-07-11 21:51       ` Jann Horn
2018-07-11 22:21         ` Andy Lutomirski
2018-07-13 18:03           ` Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 18/27] x86/cet/shstk: Introduce WRUSS instruction Yu-cheng Yu
2018-07-10 23:48   ` Dave Hansen
2018-07-12 22:59     ` Yu-cheng Yu
2018-07-12 23:49       ` Dave Hansen
2018-07-13  1:50         ` Dave Hansen
2018-07-13  2:21           ` Andy Lutomirski
2018-07-13  4:16             ` Dave Hansen
2018-07-13  4:18               ` Dave Hansen
2018-07-13 17:39                 ` Yu-cheng Yu
2018-07-13  5:55               ` Andy Lutomirski
2018-07-11  9:44   ` Peter Zijlstra
2018-07-11 15:06     ` Yu-cheng Yu
2018-07-11 15:30       ` Peter Zijlstra
2018-07-11  9:45   ` Peter Zijlstra
2018-07-11 14:58     ` Yu-cheng Yu
2018-07-11 15:27       ` Peter Zijlstra
2018-07-11 15:41         ` Yu-cheng Yu
2018-07-13 12:12   ` Dave Hansen
2018-07-13 17:37     ` Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 19/27] x86/cet/shstk: Signal handling for shadow stack Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 20/27] x86/cet/shstk: ELF header parsing of CET Yu-cheng Yu
2018-07-11 11:12   ` Florian Weimer
2018-07-11 19:37   ` Jann Horn
2018-07-11 20:53     ` Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 21/27] x86/cet/ibt: Add Kconfig option for user-mode Indirect Branch Tracking Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 22/27] x86/cet/ibt: User-mode indirect branch tracking support Yu-cheng Yu
2018-07-11  0:11   ` Dave Hansen
2018-07-11 22:10     ` Yu-cheng Yu
2018-07-11 22:40       ` Dave Hansen
2018-07-11 23:00         ` Yu-cheng Yu
2018-07-11 23:16           ` Dave Hansen
2018-07-13 17:56             ` Yu-cheng Yu
2018-07-13 18:05               ` Dave Hansen
2018-07-11 21:07   ` Jann Horn
2018-07-10 22:26 ` [RFC PATCH v2 23/27] mm/mmap: Add IBT bitmap size to address space limit check Yu-cheng Yu
2018-07-10 23:57   ` Dave Hansen
2018-07-11 16:56     ` Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 24/27] x86: Insert endbr32/endbr64 to vDSO Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 25/27] x86/cet: Add PTRACE interface for CET Yu-cheng Yu
2018-07-11 10:20   ` Ingo Molnar
2018-07-11 15:40     ` Yu-cheng Yu
2018-07-12 14:03       ` Ingo Molnar
2018-07-12 22:37         ` Yu-cheng Yu
2018-07-12 23:08           ` Thomas Gleixner
2018-07-13 16:07             ` Yu-cheng Yu
2018-07-13  6:28         ` Pavel Machek
2018-07-13 13:33           ` Ingo Molnar
2018-07-14  6:27             ` Pavel Machek
2018-07-10 22:26 ` [RFC PATCH v2 26/27] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2018-07-10 22:26 ` [RFC PATCH v2 27/27] x86/cet: Add arch_prctl functions for CET Yu-cheng Yu
2018-07-11 12:19   ` Florian Weimer
2018-07-11 21:02     ` Yu-cheng Yu
2018-07-11 19:45   ` Jann Horn
2018-07-11 20:55     ` Yu-cheng Yu [this message]

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