From: ben.hutchings@codethink.co.uk (Ben Hutchings)
To: cip-dev@lists.cip-project.org
Subject: [cip-dev] [PATCH 4.4-cip 3/6] arm64: mm: support ARCH_MMAP_RND_BITS
Date: Thu, 08 Dec 2016 23:57:51 +0000 [thread overview]
Message-ID: <1481241471.1860.123.camel@codethink.co.uk> (raw)
In-Reply-To: <1481241380.1860.120.camel@codethink.co.uk>
From: Daniel Cashman <dcashman@google.com>
commit 8f0d3aa9de57662fe35d8bacfbd9d7ef85ffe98f upstream.
arm64: arch_mmap_rnd() uses STACK_RND_MASK to generate the random offset
for the mmap base address. This value represents a compromise between
increased ASLR effectiveness and avoiding address-space fragmentation.
Replace it with a Kconfig option, which is sensibly bounded, so that
platform developers may choose where to place this compromise. Keep
default values as new minimums.
Signed-off-by: Daniel Cashman <dcashman@google.com>
Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Jeff Vander Stoep <jeffv@google.com>
Cc: Nick Kralevich <nnk@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hector Marco-Gisbert <hecmargi@upv.es>
Cc: Borislav Petkov <bp@suse.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
---
arch/arm64/Kconfig | 29 +++++++++++++++++++++++++++++
arch/arm64/mm/mmap.c | 8 ++++++--
2 files changed, 35 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 14cdc6dea493..edf62be35adc 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -51,6 +51,8 @@ config ARM64
select HAVE_ARCH_JUMP_LABEL
select HAVE_ARCH_KASAN if SPARSEMEM_VMEMMAP && !(ARM64_16K_PAGES && ARM64_VA_BITS_48)
select HAVE_ARCH_KGDB
+ select HAVE_ARCH_MMAP_RND_BITS
+ select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
select HAVE_BPF_JIT
@@ -104,6 +106,33 @@ config ARCH_PHYS_ADDR_T_64BIT
config MMU
def_bool y
+config ARCH_MMAP_RND_BITS_MIN
+ default 14 if ARM64_64K_PAGES
+ default 16 if ARM64_16K_PAGES
+ default 18
+
+# max bits determined by the following formula:
+# VA_BITS - PAGE_SHIFT - 3
+config ARCH_MMAP_RND_BITS_MAX
+ default 19 if ARM64_VA_BITS=36
+ default 24 if ARM64_VA_BITS=39
+ default 27 if ARM64_VA_BITS=42
+ default 30 if ARM64_VA_BITS=47
+ default 29 if ARM64_VA_BITS=48 && ARM64_64K_PAGES
+ default 31 if ARM64_VA_BITS=48 && ARM64_16K_PAGES
+ default 33 if ARM64_VA_BITS=48
+ default 14 if ARM64_64K_PAGES
+ default 16 if ARM64_16K_PAGES
+ default 18
+
+config ARCH_MMAP_RND_COMPAT_BITS_MIN
+ default 7 if ARM64_64K_PAGES
+ default 9 if ARM64_16K_PAGES
+ default 11
+
+config ARCH_MMAP_RND_COMPAT_BITS_MAX
+ default 16
+
config NO_IOPORT_MAP
def_bool y if !PCI
diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
index ed177475dd8c..4c893b5189dd 100644
--- a/arch/arm64/mm/mmap.c
+++ b/arch/arm64/mm/mmap.c
@@ -51,8 +51,12 @@ unsigned long arch_mmap_rnd(void)
{
unsigned long rnd;
- rnd = (unsigned long)get_random_int() & STACK_RND_MASK;
-
+#ifdef CONFIG_COMPAT
+ if (test_thread_flag(TIF_32BIT))
+ rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_compat_bits) - 1);
+ else
+#endif
+ rnd = (unsigned long)get_random_int() & ((1 << mmap_rnd_bits) - 1);
return rnd << PAGE_SHIFT;
}
--
2.10.2
--
Ben Hutchings
Software Developer, Codethink Ltd.
next prev parent reply other threads:[~2016-12-08 23:57 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-08 23:56 [cip-dev] [PATCH 4.4-cip 0/6] Extend user-space ASLR range Ben Hutchings
2016-12-08 23:57 ` [cip-dev] [PATCH 4.4-cip 1/6] mm: mmap: add new /proc tunable for mmap_base ASLR Ben Hutchings
2016-12-08 23:57 ` [cip-dev] [PATCH 4.4-cip 2/6] arm: mm: support ARCH_MMAP_RND_BITS Ben Hutchings
2016-12-08 23:57 ` Ben Hutchings [this message]
2016-12-08 23:58 ` [cip-dev] [PATCH 4.4-cip 4/6] x86: " Ben Hutchings
2016-12-08 23:58 ` [cip-dev] [PATCH 4.4-cip 5/6] drivers: char: random: add get_random_long() Ben Hutchings
2016-12-08 23:58 ` [cip-dev] [PATCH 4.4-cip 6/6] mm: ASLR: use get_random_long() Ben Hutchings
2016-12-09 12:20 ` [cip-dev] [PATCH 4.4-cip 0/6] Extend user-space ASLR range Jan Kiszka
2016-12-19 10:52 ` Jan Kiszka
2017-01-03 23:56 ` Kees Cook
2017-01-04 14:51 ` Agustin Benito Bethencourt
2017-01-12 13:40 ` Ben Hutchings
2016-12-23 16:46 ` Ben Hutchings
2017-01-02 18:48 ` Agustin Benito Bethencourt
2017-01-16 10:35 ` Agustin Benito Bethencourt
2017-01-16 10:47 ` Agustin Benito Bethencourt
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=1481241471.1860.123.camel@codethink.co.uk \
--to=ben.hutchings@codethink.co.uk \
--cc=cip-dev@lists.cip-project.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.