From mboxrd@z Thu Jan 1 00:00:00 1970 From: Balbir Singh Date: Thu, 2 Feb 2017 12:14:15 +0530 Message-ID: <20170202064415.GB5179@localhost.localdomain> References: <1486014168-1279-1-git-send-email-bhsharma@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1486014168-1279-1-git-send-email-bhsharma@redhat.com> Subject: [kernel-hardening] Re: [PATCH 0/2] RFC: Adjust powerpc ASLR elf randomness To: Bhupesh Sharma Cc: linuxppc-dev@lists.ozlabs.org, kernel-hardening@lists.openwall.com, Alistair Popple , Anatolij Gustschin , keescook@chromium.org, Daniel Cashman , Scott Wood , Paul Mackerras , dcashman@google.com, bhupesh.linux@gmail.com, Alexander Graf List-ID: On Thu, Feb 02, 2017 at 11:12:46AM +0530, Bhupesh Sharma wrote: > This RFC patchset tries to make the powerpc ASLR elf randomness > implementation similar to other ARCHs (like x86). > > The 1st patch introduces the support of ARCH_MMAP_RND_BITS in powerpc > mmap implementation to allow a sane balance between increased randomness > in the mmap address of ASLR elfs and increased address space > fragmentation. > >>From what I see we get 28 bits of entropy right for 64k pages bits as compared to 14 bits earlier? > The 2nd patch increases the ELF_ET_DYN_BASE value from the current > hardcoded value of 0x2000_0000 to something more practical, > i.e. TASK_SIZE - PAGE_SHIFT (which makes sense especially for > 64-bit platforms which would like to utilize more randomization > in the load address of a PIE elf). > This helps PIE executables as such and leaves other not impacted? Balbir Singh From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-x241.google.com (mail-pg0-x241.google.com [IPv6:2607:f8b0:400e:c05::241]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3vDVph17L8zDqGt for ; Thu, 2 Feb 2017 17:44:28 +1100 (AEDT) Received: by mail-pg0-x241.google.com with SMTP id 194so964843pgd.0 for ; Wed, 01 Feb 2017 22:44:28 -0800 (PST) From: Balbir Singh Date: Thu, 2 Feb 2017 12:14:15 +0530 To: Bhupesh Sharma Cc: linuxppc-dev@lists.ozlabs.org, kernel-hardening@lists.openwall.com, Alistair Popple , Anatolij Gustschin , keescook@chromium.org, Daniel Cashman , Scott Wood , Paul Mackerras , dcashman@google.com, bhupesh.linux@gmail.com, Alexander Graf Subject: Re: [PATCH 0/2] RFC: Adjust powerpc ASLR elf randomness Message-ID: <20170202064415.GB5179@localhost.localdomain> References: <1486014168-1279-1-git-send-email-bhsharma@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1486014168-1279-1-git-send-email-bhsharma@redhat.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, Feb 02, 2017 at 11:12:46AM +0530, Bhupesh Sharma wrote: > This RFC patchset tries to make the powerpc ASLR elf randomness > implementation similar to other ARCHs (like x86). > > The 1st patch introduces the support of ARCH_MMAP_RND_BITS in powerpc > mmap implementation to allow a sane balance between increased randomness > in the mmap address of ASLR elfs and increased address space > fragmentation. > >>From what I see we get 28 bits of entropy right for 64k pages bits as compared to 14 bits earlier? > The 2nd patch increases the ELF_ET_DYN_BASE value from the current > hardcoded value of 0x2000_0000 to something more practical, > i.e. TASK_SIZE - PAGE_SHIFT (which makes sense especially for > 64-bit platforms which would like to utilize more randomization > in the load address of a PIE elf). > This helps PIE executables as such and leaves other not impacted? Balbir Singh