Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754523Ab1DTNk7 (ORCPT ); Wed, 20 Apr 2011 09:40:59 -0400 Received: from mail-iw0-f174.google.com ([209.85.214.174]:39269 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752710Ab1DTNk6 convert rfc822-to-8bit (ORCPT ); Wed, 20 Apr 2011 09:40:58 -0400 MIME-Version: 1.0 In-Reply-To: <20110419062654.GB10698@linux.vnet.ibm.com> References: <20110401143223.15455.19844.sendpatchset@localhost6.localdomain6> <20110401143457.15455.64839.sendpatchset@localhost6.localdomain6> <1303145171.32491.886.camel@twins> <20110419062654.GB10698@linux.vnet.ibm.com> Date: Wed, 20 Apr 2011 09:40:57 -0400 Message-ID: Subject: Re: [PATCH v3 2.6.39-rc1-tip 12/26] 12: uprobes: slot allocation for uprobes From: Eric Paris To: Srikar Dronamraju Cc: Peter Zijlstra , James Morris , Ingo Molnar , Steven Rostedt , Linux-mm , Arnaldo Carvalho de Melo , Linus Torvalds , Jonathan Corbet , Christoph Hellwig , Masami Hiramatsu , Thomas Gleixner , Ananth N Mavinakayanahalli , Oleg Nesterov , Andrew Morton , SystemTap , Jim Keniston , Roland McGrath , Andi Kleen , LKML , Eric Paris , sds@tycho.nsa.gov Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3160 Lines: 84 On Tue, Apr 19, 2011 at 2:26 AM, Srikar Dronamraju wrote: > * Peter Zijlstra [2011-04-18 18:46:11]: > >> On Fri, 2011-04-01 at 20:04 +0530, Srikar Dronamraju wrote: >> > +static int xol_add_vma(struct uprobes_xol_area *area) >> > +{ >> > + ? struct vm_area_struct *vma; >> > + ? struct mm_struct *mm; >> > + ? struct file *file; >> > + ? unsigned long addr; >> > + ? int ret = -ENOMEM; >> > + >> > + ? mm = get_task_mm(current); >> > + ? if (!mm) >> > + ? ? ? ? ? return -ESRCH; >> > + >> > + ? down_write(&mm->mmap_sem); >> > + ? if (mm->uprobes_xol_area) { >> > + ? ? ? ? ? ret = -EALREADY; >> > + ? ? ? ? ? goto fail; >> > + ? } >> > + >> > + ? /* >> > + ? ?* Find the end of the top mapping and skip a page. >> > + ? ?* If there is no space for PAGE_SIZE above >> > + ? ?* that, mmap will ignore our address hint. >> > + ? ?* >> > + ? ?* We allocate a "fake" unlinked shmem file because >> > + ? ?* anonymous memory might not be granted execute >> > + ? ?* permission when the selinux security hooks have >> > + ? ?* their way. >> > + ? ?*/ >> >> That just annoys me, so we're working around some stupid sekurity crap, >> executable anonymous maps are perfectly fine, also what do JITs do? > > Yes, we are working around selinux security hooks, but do we have a > choice. > > James can you please comment on this. [added myself and stephen, the 2 SELinux maintainers] This is just wrong. Anything to 'work around' SELinux in the kernel is wrong. SELinux access decisions are determined by policy not by dirty hacks in the code to subvert any kind of security claims that policy might hope to enforce. [side note, security_file_mmap() is the right call if there is a file or not. It should just be called security_mmap() but the _file_ has been around a long time and just never had a need to be changed] Now how to fix the problems you were seeing. If you run a modern system with a GUI I'm willing to bet the pop-up window told you exactly how to fix your problem. If you are not on a GUI I accept it's a more difficult as you most likely don't have the setroubleshoot tools installed to help you out. I'm just guess what your problem was, but I think you have two solutions either: 1) chcon -t unconfined_execmem_t /path/to/your/binary 2) setsebool -P allow_execmem 1 The first will cause the binary to execute in a domain with permissions to execute anonymous memory, the second will allow all unconfined domains to execute anonymous memory. I believe there was a question about how JIT's work with SELinux systems. They work mostly by method #1. I did hear this question though: On a different but related note, how is the use of uprobes controlled? Does it apply the same checking as for ptrace? Thanks guys! If you have SELinux or LSM problems in the future let me know. It's likely the solution is easier than you imagine ;) -Eric -- 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/