The patch titled
Subject: x86: mm: support ARCH_MMAP_RND_BITS
has been added to the -mm tree. Its filename is
x86-mm-support-arch_mmap_rnd_bits.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/x86-mm-support-arch_mmap_rnd_bits.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/x86-mm-support-arch_mmap_rnd_bits.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Daniel Cashman <dcashman@xxxxxxxxxx>
Subject: x86: mm: support ARCH_MMAP_RND_BITS
x86: arch_mmap_rnd() uses hard-coded values, 8 for 32-bit and 28 for
64-bit, 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@xxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Don Zickus <dzickus@xxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Heinrich Schuchardt <xypron.glpk@xxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Mark Salyzyn <salyzyn@xxxxxxxxxxx>
Cc: Jeff Vander Stoep <jeffv@xxxxxxxxxx>
Cc: Nick Kralevich <nnk@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Hector Marco-Gisbert <hecmargi@xxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc; Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc; Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/Kconfig | 16 ++++++++++++++++
arch/x86/mm/mmap.c | 12 ++++++------
2 files changed, 22 insertions(+), 6 deletions(-)
diff -puN arch/x86/Kconfig~x86-mm-support-arch_mmap_rnd_bits arch/x86/Kconfig
--- a/arch/x86/Kconfig~x86-mm-support-arch_mmap_rnd_bits
+++ a/arch/x86/Kconfig
@@ -82,6 +82,8 @@ config X86
select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP
select HAVE_ARCH_KGDB
select HAVE_ARCH_KMEMCHECK
+ select HAVE_ARCH_MMAP_RND_BITS
+ select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_SOFT_DIRTY if X86_64
select HAVE_ARCH_TRACEHOOK
@@ -183,6 +185,20 @@ config HAVE_LATENCYTOP_SUPPORT
config MMU
def_bool y
+config ARCH_MMAP_RND_BITS_MIN
+ default 28 if 64BIT
+ default 8
+
+config ARCH_MMAP_RND_BITS_MAX
+ default 32 if 64BIT
+ default 16
+
+config ARCH_MMAP_RND_COMPAT_BITS_MIN
+ default 8
+
+config ARCH_MMAP_RND_COMPAT_BITS_MAX
+ default 16
+
config SBUS
bool
diff -puN arch/x86/mm/mmap.c~x86-mm-support-arch_mmap_rnd_bits arch/x86/mm/mmap.c
--- a/arch/x86/mm/mmap.c~x86-mm-support-arch_mmap_rnd_bits
+++ a/arch/x86/mm/mmap.c
@@ -69,14 +69,14 @@ unsigned long arch_mmap_rnd(void)
{
unsigned long rnd;
- /*
- * 8 bits of randomness in 32bit mmaps, 20 address space bits
- * 28 bits of randomness in 64bit mmaps, 40 address space bits
- */
if (mmap_is_ia32())
- rnd = (unsigned long)get_random_int() % (1<<8);
+#ifdef CONFIG_COMPAT
+ rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_compat_bits);
+#else
+ rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_bits);
+#endif
else
- rnd = (unsigned long)get_random_int() % (1<<28);
+ rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_bits);
return rnd << PAGE_SHIFT;
}
_
Patches currently in -mm which might be from dcashman@xxxxxxxxxx are
mm-mmap-add-new-proc-tunable-for-mmap_base-aslr.patch
arm-mm-support-arch_mmap_rnd_bits.patch
arm64-mm-support-arch_mmap_rnd_bits.patch
x86-mm-support-arch_mmap_rnd_bits.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
