From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 2AF936B0010 for ; Fri, 23 Mar 2018 08:50:02 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id a4so6587655pff.2 for ; Fri, 23 Mar 2018 05:50:02 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [2607:7c80:54:e::133]) by mx.google.com with ESMTPS id e92-v6si4557535plb.519.2018.03.23.05.50.00 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 23 Mar 2018 05:50:00 -0700 (PDT) Date: Fri, 23 Mar 2018 05:48:06 -0700 From: Matthew Wilcox Subject: Re: [RFC PATCH v2 0/2] Randomization of address chosen by mmap. Message-ID: <20180323124806.GA5624@bombadil.infradead.org> References: <1521736598-12812-1-git-send-email-blackzert@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1521736598-12812-1-git-send-email-blackzert@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Ilya Smith Cc: rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@synopsys.com, linux@armlinux.org.uk, tony.luck@intel.com, fenghua.yu@intel.com, jhogan@kernel.org, ralf@linux-mips.org, jejb@parisc-linux.org, deller@gmx.de, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, nyc@holomorphy.com, viro@zeniv.linux.org.uk, arnd@arndb.de, gregkh@linuxfoundation.org, deepa.kernel@gmail.com, mhocko@suse.com, hughd@google.com, kstewart@linuxfoundation.org, pombredanne@nexb.com, akpm@linux-foundation.org, steve.capper@arm.com, punit.agrawal@arm.com, paul.burton@mips.com, aneesh.kumar@linux.vnet.ibm.com, npiggin@gmail.com, keescook@chromium.org, bhsharma@redhat.com, riel@redhat.com, nitin.m.gupta@oracle.com, kirill.shutemov@linux.intel.com, dan.j.williams@intel.com, jack@suse.cz, ross.zwisler@linux.intel.com, jglisse@redhat.com, aarcange@redhat.com, oleg@redhat.com, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-metag@vger.kernel.org, linux-mips@linux-mips.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-mm@kvack.org On Thu, Mar 22, 2018 at 07:36:36PM +0300, Ilya Smith wrote: > Current implementation doesn't randomize address returned by mmap. > All the entropy ends with choosing mmap_base_addr at the process > creation. After that mmap build very predictable layout of address > space. It allows to bypass ASLR in many cases. This patch make > randomization of address on any mmap call. Why should this be done in the kernel rather than libc? libc is perfectly capable of specifying random numbers in the first argument of mmap.