Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752208AbbLKSAF (ORCPT ); Fri, 11 Dec 2015 13:00:05 -0500 Received: from mail-pf0-f169.google.com ([209.85.192.169]:36215 "EHLO mail-pf0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751048AbbLKSAB (ORCPT ); Fri, 11 Dec 2015 13:00:01 -0500 From: Daniel Cashman To: linux-kernel@vger.kernel.org Cc: linux@arm.linux.org.uk, akpm@linux-foundation.org, keescook@chromium.org, mingo@kernel.org, linux-arm-kernel@lists.infradead.org, corbet@lwn.net, dzickus@redhat.com, ebiederm@xmission.com, xypron.glpk@gmx.de, jpoimboe@redhat.com, kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com, aarcange@redhat.com, mgorman@suse.de, tglx@linutronix.de, rientjes@google.com, linux-mm@kvack.org, linux-doc@vger.kernel.org, salyzyn@android.com, jeffv@google.com, nnk@google.com, catalin.marinas@arm.com, will.deacon@arm.com, hpa@zytor.com, x86@kernel.org, hecmargi@upv.es, bp@suse.de, dcashman@google.com, arnd@arndb.de, jonathanh@nvidia.com, Daniel Cashman Subject: [PATCH v6 3/4] arm64: mm: support ARCH_MMAP_RND_BITS. Date: Fri, 11 Dec 2015 09:52:17 -0800 Message-Id: <1449856338-30984-4-git-send-email-dcashman@android.com> X-Mailer: git-send-email 2.6.0.rc2.230.g3dd15c0 In-Reply-To: <1449856338-30984-3-git-send-email-dcashman@android.com> References: <1449856338-30984-1-git-send-email-dcashman@android.com> <1449856338-30984-2-git-send-email-dcashman@android.com> <1449856338-30984-3-git-send-email-dcashman@android.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3090 Lines: 93 From: dcashman 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 --- arch/arm64/Kconfig | 33 +++++++++++++++++++++++++++++++++ arch/arm64/mm/mmap.c | 8 ++++++-- 2 files changed, 39 insertions(+), 2 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 871f217..0cc9c24 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 +106,37 @@ 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 20 if ARM64_64K_PAGES && ARM64_VA_BITS=39 + default 22 if ARM64_16K_PAGES && ARM64_VA_BITS=39 + default 24 if ARM64_VA_BITS=39 + default 23 if ARM64_64K_PAGES && ARM64_VA_BITS=42 + default 25 if ARM64_16K_PAGES && ARM64_VA_BITS=42 + default 27 if ARM64_VA_BITS=42 + default 30 if ARM64_VA_BITS=47 + default 29 if ARM64_64K_PAGES && ARM64_VA_BITS=48 + default 31 if ARM64_16K_PAGES && ARM64_VA_BITS=48 + default 33 if ARM64_VA_BITS=48 + default 15 if ARM64_64K_PAGES + default 17 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 ed17747..e59a75a 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); + else +#endif + rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_bits); return rnd << PAGE_SHIFT; } -- 2.6.0.rc2.230.g3dd15c0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/