linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Andrey Konovalov <andreyknvl@google.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Alexander Potapenko <glider@google.com>,
	Marco Elver <elver@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Will Deacon <will.deacon@arm.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Evgenii Stepanov <eugenis@google.com>,
	Branislav Rankov <Branislav.Rankov@arm.com>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH 02/11] kasan: clarify HW_TAGS impact on TBI
Date: Tue,  5 Jan 2021 19:27:46 +0100	[thread overview]
Message-ID: <a5dfc703ddd7eacda0ee0da083c7afad44afff8c.1609871239.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1609871239.git.andreyknvl@google.com>

Mention in the documentation that enabling CONFIG_KASAN_HW_TAGS
always results in in-kernel TBI (Top Byte Ignore) being enabled.

Also do a few minor documentation cleanups.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Link: https://linux-review.googlesource.com/id/Iba2a6697e3c6304cb53f89ec61dedc77fa29e3ae
---
 Documentation/dev-tools/kasan.rst | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index 0fc3fb1860c4..26c99852a852 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst
@@ -147,15 +147,14 @@ negative values to distinguish between different kinds of inaccessible memory
 like redzones or freed memory (see mm/kasan/kasan.h).
 
 In the report above the arrows point to the shadow byte 03, which means that
-the accessed address is partially accessible.
-
-For tag-based KASAN this last report section shows the memory tags around the
-accessed address (see `Implementation details`_ section).
+the accessed address is partially accessible. For tag-based KASAN modes this
+last report section shows the memory tags around the accessed address
+(see the `Implementation details`_ section).
 
 Boot parameters
 ~~~~~~~~~~~~~~~
 
-Hardware tag-based KASAN mode (see the section about different mode below) is
+Hardware tag-based KASAN mode (see the section about various modes below) is
 intended for use in production as a security mitigation. Therefore it supports
 boot parameters that allow to disable KASAN competely or otherwise control
 particular KASAN features.
@@ -305,6 +304,13 @@ reserved to tag freed memory regions.
 Hardware tag-based KASAN currently only supports tagging of
 kmem_cache_alloc/kmalloc and page_alloc memory.
 
+If the hardware doesn't support MTE (pre ARMv8.5), hardware tag-based KASAN
+won't be enabled. In this case all boot parameters are ignored.
+
+Note, that enabling CONFIG_KASAN_HW_TAGS always results in in-kernel TBI being
+enabled. Even when kasan.mode=off is provided, or when the hardware doesn't
+support MTE (but supports TBI).
+
 What memory accesses are sanitised by KASAN?
 --------------------------------------------
 
-- 
2.29.2.729.g45daf8777d-goog


  parent reply	other threads:[~2021-01-05 18:28 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-05 18:27 [PATCH 00/11] kasan: HW_TAGS tests support and fixes Andrey Konovalov
2021-01-05 18:27 ` [PATCH 01/11] kasan: prefix exported functions with kasan_ Andrey Konovalov
2021-01-12  7:38   ` Alexander Potapenko
2021-01-12 11:19   ` Marco Elver
2021-01-05 18:27 ` Andrey Konovalov [this message]
2021-01-12  7:40   ` [PATCH 02/11] kasan: clarify HW_TAGS impact on TBI Alexander Potapenko
2021-01-12 11:38   ` Marco Elver
2021-01-05 18:27 ` [PATCH 03/11] kasan: clean up comments in tests Andrey Konovalov
2021-01-12  7:53   ` Alexander Potapenko
2021-01-12 17:55     ` Andrey Konovalov
2021-01-12 13:07   ` Marco Elver
2021-01-05 18:27 ` [PATCH 04/11] kasan: add match-all tag tests Andrey Konovalov
2021-01-12  8:04   ` Alexander Potapenko
2021-01-12 18:10     ` Andrey Konovalov
2021-01-12 13:17   ` Marco Elver
2021-01-12 18:11     ` Andrey Konovalov
2021-01-05 18:27 ` [PATCH 05/11] kasan, arm64: allow using KUnit tests with HW_TAGS mode Andrey Konovalov
2021-01-12 19:01   ` Catalin Marinas
2021-01-15 13:11     ` Andrey Konovalov
2021-01-15 15:04   ` Vincenzo Frascino
2021-01-05 18:27 ` [PATCH 06/11] kasan: rename CONFIG_TEST_KASAN_MODULE Andrey Konovalov
2021-01-12  8:09   ` Alexander Potapenko
2021-01-12 18:26     ` Andrey Konovalov
2021-01-12 13:33   ` Marco Elver
2021-01-12 18:28     ` Andrey Konovalov
2021-01-05 18:27 ` [PATCH 07/11] kasan: add compiler barriers to KUNIT_EXPECT_KASAN_FAIL Andrey Konovalov
2021-01-12  8:18   ` Alexander Potapenko
2021-01-12 19:50     ` Andrey Konovalov
2021-01-12 19:57       ` Andrey Konovalov
2021-01-12 13:34   ` Marco Elver
2021-01-05 18:27 ` [PATCH 08/11] kasan: adopt kmalloc_uaf2 test to HW_TAGS mode Andrey Konovalov
2021-01-12  8:25   ` Alexander Potapenko
2021-01-12 20:04     ` Andrey Konovalov
2021-01-12 13:39   ` Marco Elver
2021-01-12 20:05     ` Andrey Konovalov
2021-01-05 18:27 ` [PATCH 09/11] kasan: fix memory corruption in kasan_bitops_tags test Andrey Konovalov
2021-01-12  8:30   ` Alexander Potapenko
2021-01-12 20:06     ` Andrey Konovalov
2021-01-13 12:30       ` Alexander Potapenko
2021-01-12 13:55   ` Marco Elver
2021-01-05 18:27 ` [PATCH 10/11] kasan: fix bug detection via ksize for HW_TAGS mode Andrey Konovalov
2021-01-12 14:32   ` Marco Elver
2021-01-12 21:16     ` Andrey Konovalov
2021-01-12 22:54       ` Marco Elver
2021-01-05 18:27 ` [PATCH 11/11] kasan: add proper page allocator tests Andrey Konovalov
2021-01-12  8:57   ` Alexander Potapenko
2021-01-12 14:34   ` Marco Elver

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=a5dfc703ddd7eacda0ee0da083c7afad44afff8c.1609871239.git.andreyknvl@google.com \
    --to=andreyknvl@google.com \
    --cc=Branislav.Rankov@arm.com \
    --cc=akpm@linux-foundation.org \
    --cc=aryabinin@virtuozzo.com \
    --cc=catalin.marinas@arm.com \
    --cc=dvyukov@google.com \
    --cc=elver@google.com \
    --cc=eugenis@google.com \
    --cc=glider@google.com \
    --cc=kasan-dev@googlegroups.com \
    --cc=kevin.brodsky@arm.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=vincenzo.frascino@arm.com \
    --cc=will.deacon@arm.com \
    --subject='Re: [PATCH 02/11] kasan: clarify HW_TAGS impact on TBI' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
on how to clone and mirror all data and code used for this inbox