From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 3E5066B003D for ; Tue, 31 Mar 2009 10:36:52 -0400 (EDT) Received: by qyk15 with SMTP id 15so5406345qyk.12 for ; Tue, 31 Mar 2009 07:37:23 -0700 (PDT) Message-ID: <49D22A9D.4050403@codemonkey.ws> Date: Tue, 31 Mar 2009 09:37:17 -0500 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [PATCH 4/4] add ksm kernel shared memory driver. References: <1238457560-7613-1-git-send-email-ieidus@redhat.com> <1238457560-7613-2-git-send-email-ieidus@redhat.com> <1238457560-7613-3-git-send-email-ieidus@redhat.com> <1238457560-7613-4-git-send-email-ieidus@redhat.com> <1238457560-7613-5-git-send-email-ieidus@redhat.com> <49D17C04.9070307@codemonkey.ws> <49D20B63.8020709@redhat.com> <49D21B33.4070406@codemonkey.ws> <20090331142533.GR9137@random.random> In-Reply-To: <20090331142533.GR9137@random.random> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Andrea Arcangeli Cc: Izik Eidus , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, avi@redhat.com, chrisw@redhat.com, riel@redhat.com, jeremy@goop.org, mtosatti@redhat.com, hugh@veritas.com, corbet@lwn.net, yaniv@redhat.com, dmonakhov@openvz.org List-ID: Andrea Arcangeli wrote: >> the ability to disable KSM. That seems like a security concern to me since >> registering a memory region ought to be an unprivileged action whereas >> enabling/disabling KSM ought to be a privileged action. >> > > sysfs files would then only be writeable by admin, so if we want to > allow only admin to start/stop/tune ksm it'd be enough to plug an > admin capability check in the ioctl to provide equivalent permissions. > Caps are not very granular unless you introduce a new capability. Furthermore, it's a bit more difficult to associate a capability with a user/group. With sysfs, you use file based permissions to control the API. It also fits into things like selinux a lot better. In the very least, if you insist on not using sysfs, you should have a separate character device that's used for control (like /dev/ksmctl). Regards, Anthony Liguori > I could imagine converting the enable/pages_to_scan/sleep_time to > module params and tweaking them through /sys/module/ksm/parameters, > but for "enable" to work that way, we'd need to intercept the write so > we can at least weakup the kksmd daemon, which doesn't seem possible > with /sys/module/ksm/parameters, so in the end if we stick to the > ioctl for registering regions, it seems simpler to use it for > start/stop/tune too. > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org