From: Borislav Petkov <bp@alien8.de>
To: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-mm@kvack.org, linux-arch@vger.kernel.org,
linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Andy Lutomirski <luto@amacapital.net>,
Balbir Singh <bsingharora@gmail.com>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Eugene Syromiatnikov <esyr@redhat.com>,
Florian Weimer <fweimer@redhat.com>,
"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
Jonathan Corbet <corbet@lwn.net>,
Kees Cook <keescook@chromium.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>,
Randy Dunlap <rdunlap@infradead.org>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>
Subject: Re: [PATCH v5 05/27] Documentation/x86: Add CET description
Date: Tue, 13 Nov 2018 19:43:37 +0100 [thread overview]
Message-ID: <20181113184337.GM10502@zn.tnic> (raw)
In-Reply-To: <20181011151523.27101-6-yu-cheng.yu@intel.com>
On Thu, Oct 11, 2018 at 08:15:01AM -0700, Yu-cheng Yu wrote:
> Explain how CET works and the no_cet_shstk/no_cet_ibt kernel
> parameters.
>
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
> ---
> .../admin-guide/kernel-parameters.txt | 6 +
> Documentation/index.rst | 1 +
> Documentation/x86/index.rst | 11 +
> Documentation/x86/intel_cet.rst | 266 ++++++++++++++++++
> 4 files changed, 284 insertions(+)
> create mode 100644 Documentation/x86/index.rst
> create mode 100644 Documentation/x86/intel_cet.rst
So this patch should probably come first in the series so that a reader
can know what to expect...
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 92eb1f42240d..3854423f7c86 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2764,6 +2764,12 @@
> noexec=on: enable non-executable mappings (default)
> noexec=off: disable non-executable mappings
>
> + no_cet_ibt [X86-64] Disable indirect branch tracking for user-mode
> + applications
> +
> + no_cet_shstk [X86-64] Disable shadow stack support for user-mode
> + applications
> +
> nosmap [X86]
> Disable SMAP (Supervisor Mode Access Prevention)
> even if it is supported by processor.
> diff --git a/Documentation/index.rst b/Documentation/index.rst
> index 5db7e87c7cb1..1cdc139adb40 100644
> --- a/Documentation/index.rst
> +++ b/Documentation/index.rst
Please integrate scripts/checkpatch.pl into your patch creation
workflow. Some of the warnings/errors *actually* make sense:
WARNING: Missing or malformed SPDX-License-Identifier tag in line 1
#76: FILE: Documentation/x86/index.rst:1:
+=======================
WARNING: Missing or malformed SPDX-License-Identifier tag in line 1
#93: FILE: Documentation/x86/intel_cet.rst:1:
+=========================================
> @@ -104,6 +104,7 @@ implementation.
> :maxdepth: 2
>
> sh/index
> + x86/index
>
> Filesystem Documentation
> ------------------------
> diff --git a/Documentation/x86/index.rst b/Documentation/x86/index.rst
> new file mode 100644
> index 000000000000..9c34d8cbc8f0
> --- /dev/null
> +++ b/Documentation/x86/index.rst
> @@ -0,0 +1,11 @@
> +=======================
> +X86 Documentation
> +=======================
> +
> +Control Flow Enforcement
> +========================
> +
> +.. toctree::
> + :maxdepth: 1
> +
> + intel_cet
> diff --git a/Documentation/x86/intel_cet.rst b/Documentation/x86/intel_cet.rst
> new file mode 100644
> index 000000000000..946f4802a51f
> --- /dev/null
> +++ b/Documentation/x86/intel_cet.rst
> @@ -0,0 +1,266 @@
> +=========================================
> +Control Flow Enforcement Technology (CET)
> +=========================================
> +
> +[1] Overview
> +============
> +
> +Control Flow Enforcement Technology (CET) provides protection against
> +return/jump-oriented programming (ROP) attacks. It can be implemented
> +to protect both the kernel and applications. In the first phase,
> +only the user-mode protection is implemented on the 64-bit kernel.
s/the// is implemented in 64-bit mode.
> +However, 32-bit applications are supported under the compatibility
> +mode.
Drop "However":
"32-bit applications are, of course, supported in compatibility mode."
> +
> +CET includes shadow stack (SHSTK) and indirect branch tracking (IBT).
"CET introduces two a shadow stack and an indirect branch tracking mechanism."
> +The SHSTK is a secondary stack allocated from memory. The processor
s/The//
> +automatically pushes/pops a secure copy to the SHSTK every return
> +address and,
that reads funny - pls reorganize. Also, what is a "secure copy"?
You mean a copy of every return address which software cannot access?
> by comparing the secure copy to the program stack copy,
> +verifies function returns are as intended.
... have not been corrupted/modified."
> The IBT verifies all
> +indirect CALL/JMP targets are intended and marked by the compiler with
> +'ENDBR' op codes.
"opcode" - one word. And before you use "ENDBR" you need to explain it
above what it is.
/me reads further... encounters ENDBR's definition...
ah, ok, so you should say something like
"... and marked by the compiler with the ENDBR opcode (see below)."
> +
> +There are two kernel configuration options:
> +
> + INTEL_X86_SHADOW_STACK_USER, and
> + INTEL_X86_BRANCH_TRACKING_USER.
> +
> +To build a CET-enabled kernel, Binutils v2.31 and GCC v8.1 or later
> +are required. To build a CET-enabled application, GLIBC v2.28 or
> +later is also required.
> +
> +There are two command-line options for disabling CET features:
> +
> + no_cet_shstk - disables SHSTK, and
> + no_cet_ibt - disables IBT.
> +
> +At run time, /proc/cpuinfo shows the availability of SHSTK and IBT.
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2018-11-13 18:43 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-11 15:14 [PATCH v5 00/27] Control Flow Enforcement: Shadow Stack Yu-cheng Yu
2018-10-11 15:14 ` [PATCH v5 01/27] x86/cpufeatures: Add CPUIDs for Control Flow Enforcement Technology (CET) Yu-cheng Yu
2018-10-11 16:43 ` Borislav Petkov
2018-10-11 16:45 ` Yu-cheng Yu
2018-10-11 15:14 ` [PATCH v5 02/27] x86/fpu/xstate: Change names to separate XSAVES system and user states Yu-cheng Yu
2018-10-15 17:03 ` Borislav Petkov
2018-10-11 15:14 ` [PATCH v5 03/27] x86/fpu/xstate: Introduce XSAVES system states Yu-cheng Yu
2018-10-17 10:41 ` Borislav Petkov
2018-10-17 22:39 ` Randy Dunlap
2018-10-17 22:58 ` Borislav Petkov
2018-10-17 23:17 ` Randy Dunlap
2018-10-18 9:26 ` Borislav Petkov
2018-10-18 9:31 ` Pavel Machek
2018-10-18 12:10 ` Borislav Petkov
2018-10-18 18:33 ` Randy Dunlap
2018-10-18 9:24 ` Pavel Machek
2018-10-11 15:15 ` [PATCH v5 04/27] x86/fpu/xstate: Add XSAVES system states for shadow stack Yu-cheng Yu
2018-11-08 18:40 ` Borislav Petkov
2018-11-08 20:40 ` Yu-cheng Yu
2018-11-08 23:52 ` Borislav Petkov
2018-11-11 11:31 ` Pavel Machek
2018-11-11 11:31 ` Pavel Machek
2018-11-11 14:59 ` Andy Lutomirski
2018-11-11 19:02 ` Pavel Machek
2018-11-08 20:46 ` Andy Lutomirski
2018-11-08 21:01 ` Yu-cheng Yu
2018-11-08 21:22 ` Andy Lutomirski
2018-11-08 21:31 ` Cyrill Gorcunov
2018-11-08 22:01 ` Andy Lutomirski
2018-11-08 22:18 ` Cyrill Gorcunov
2018-11-08 21:48 ` Dave Hansen
2018-11-08 22:00 ` Matthew Wilcox
2018-11-08 23:35 ` Dave Hansen
2018-11-09 0:32 ` Matthew Wilcox
2018-11-09 0:45 ` Andy Lutomirski
2018-11-09 17:13 ` Dave Hansen
2018-11-09 17:17 ` Matthew Wilcox
2018-11-09 17:20 ` Dave Hansen
2018-11-09 17:28 ` Dave Hansen
2018-11-11 11:31 ` Pavel Machek
2018-10-11 15:15 ` [PATCH v5 05/27] Documentation/x86: Add CET description Yu-cheng Yu
2018-11-13 18:43 ` Borislav Petkov [this message]
2018-11-13 21:02 ` Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 06/27] x86/cet: Control protection exception handler Yu-cheng Yu
2018-11-14 18:44 ` Borislav Petkov
2018-11-14 20:19 ` Yu-cheng Yu
2018-11-14 20:28 ` Borislav Petkov
2018-10-11 15:15 ` [PATCH v5 07/27] mm/mmap: Create a guard area between VMAs Yu-cheng Yu
2018-10-11 20:39 ` Jann Horn
2018-10-11 20:49 ` Yu-cheng Yu
2018-10-11 20:55 ` Andy Lutomirski
2018-10-12 21:49 ` Yu-cheng Yu
2018-10-12 13:17 ` Matthew Wilcox
2018-10-11 20:49 ` Dave Hansen
2018-10-12 10:24 ` Florian Weimer
2018-10-11 15:15 ` [PATCH v5 08/27] x86/cet/shstk: Add Kconfig option for user-mode shadow stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 09/27] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 10/27] mm/mmap: Prevent Shadow Stack VMA merges Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 11/27] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 12/27] x86/mm: Introduce _PAGE_DIRTY_SW Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 13/27] drm/i915/gvt: Update _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 14/27] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 15/27] x86/mm: Shadow stack page fault error checking Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 16/27] mm: Handle shadow stack page fault Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 17/27] mm: Handle THP/HugeTLB " Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 18/27] mm: Update can_follow_write_pte/pmd for shadow stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 19/27] mm: Introduce do_mmap_locked() Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 20/27] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 21/27] x86/cet/shstk: Introduce WRUSS instruction Yu-cheng Yu
2018-11-06 18:43 ` Dave Hansen
2018-11-06 18:55 ` Andy Lutomirski
2018-11-06 20:21 ` Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 22/27] x86/cet/shstk: Signal handling for shadow stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 23/27] x86/cet/shstk: ELF header parsing of Shadow Stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 24/27] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 25/27] mm/mmap: Add Shadow stack pages to memory accounting Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 26/27] x86/cet/shstk: Add arch_prctl functions for Shadow Stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 27/27] x86/cet/shstk: Add Shadow Stack instructions to opcode map Yu-cheng Yu
2018-10-11 19:21 ` [PATCH v5 00/27] Control Flow Enforcement: Shadow Stack Dave Hansen
2018-10-11 19:29 ` Yu-cheng Yu
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