On Thu, Sep 05, 2013 at 10:47:15AM -0400, Vivek Goyal wrote: > On Thu, Sep 05, 2013 at 02:40:39PM +0000, Matthew Garrett wrote: > > On Wed, 2013-09-04 at 20:49 -0400, Vivek Goyal wrote: > > > > > I did what Eric Biederman suggested. I first unshare the mount namespace > > > of /sbin/kexec from parent. Then I disable any event propogation between > > > mounts. Then I lazy unmount existing /proc and /sys and remount them. I > > > think this should make sure that we are seeing at /proc and /sys as > > > exported by kenrel? > > > > Namespaces have mostly been used with the assumption that namespaces > > contain child processes, rather than parent processes attacking > > children. Are we guaranteed that (barring ptrace) a parent process is > > unable to manipulate a child's namespaces? > > This is a good question and I don't know enough about namespaces to > be able to answer it. > > I am CCing Eric Biederman and he should have an Idea. > > Eric, > > So this is in context of kdump an secureboot. We were discussing to be > able to create a private mount namespace for /sbin/kexec and remount > /proc/ and /sys so that /sbin/kexec is sure that it is looking at > something as exported by kernel. > > Is it possible for unsigned parent to now maninpulate child /sbin/kexec > mount namespace now? I am not an expert in this area. I am reading following two articles. http://man7.org/linux/man-pages/man2/mount.2.html http://www.ibm.com/developerworks/linux/library/l-mount-namespaces/index.html I think once we did unshare() child got its own mount name space and after that we converted it into a private mount point. I think that will ensure that no mount events are propagated from parent to child and vice-a-versa. I doubt that now there is any way a parent can modify child's mount namespace. Thanks Vivek _______________________________________________ kernel mailing list kernel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/kernel
