Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933369AbbKRWs7 (ORCPT ); Wed, 18 Nov 2015 17:48:59 -0500 Received: from mail-pa0-f54.google.com ([209.85.220.54]:36200 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757320AbbKRWsu (ORCPT ); Wed, 18 Nov 2015 17:48:50 -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 Subject: [PATCH 3/4] arm64: mm: support ARCH_MMAP_RND_BITS. Date: Wed, 18 Nov 2015 14:48:20 -0800 Message-Id: <1447886901-26098-4-git-send-email-dcashman@android.com> X-Mailer: git-send-email 2.6.0.rc2.230.g3dd15c0 In-Reply-To: <1447886901-26098-3-git-send-email-dcashman@android.com> References: <1447886901-26098-1-git-send-email-dcashman@android.com> <1447886901-26098-2-git-send-email-dcashman@android.com> <1447886901-26098-3-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: 2556 Lines: 81 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 | 23 +++++++++++++++++++++++ arch/arm64/mm/mmap.c | 6 ++++-- 2 files changed, 27 insertions(+), 2 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 9ac16a4..be38e4c 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 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 +106,27 @@ config ARCH_PHYS_ADDR_T_64BIT config MMU def_bool y +config ARCH_MMAP_RND_BITS_MIN + default 15 if ARM64_64K_PAGES + default 19 + +config ARCH_MMAP_RND_BITS_MAX + default 20 if ARM64_64K_PAGES && ARCH_VA_BITS=39 + default 24 if ARCH_VA_BITS=39 + default 23 if ARM64_64K_PAGES && ARCH_VA_BITS=42 + default 27 if ARCH_VA_BITS=42 + default 29 if ARM64_64K_PAGES && ARCH_VA_BITS=48 + default 33 if ARCH_VA_BITS=48 + default 15 if ARM64_64K_PAGES + default 19 + +config ARCH_MMAP_RND_COMPAT_BITS_MIN + default 7 if ARM64_64K_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..b84d5b1 100644 --- a/arch/arm64/mm/mmap.c +++ b/arch/arm64/mm/mmap.c @@ -51,8 +51,10 @@ unsigned long arch_mmap_rnd(void) { unsigned long rnd; - rnd = (unsigned long)get_random_int() & STACK_RND_MASK; - + if (test_thread_flag(TIF_32BIT)) + rnd = (unsigned long)get_random_int() % (1 << mmap_rnd_compat_bits); + else + 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/