On Thu, 6 Sep 2007, Satyam Sharma wrote: > > On Thu, 30 Aug 2007, J. Bruce Fields wrote: > > > On Thu, Aug 30, 2007 at 11:04:00AM -0400, Trond Myklebust wrote: > > > > > What I'm saying is that the superuser can pretty much do whatever it > > > takes to grab either your kerberos password (e.g. install a keyboard > > > listener), a stored credential (read the contents of your kerberos > > > on-disk credential cache), or s/he can access the cached contents of the > > > file by hunting through /dev/kmem. > > > > > > IOW: There is no such thing as security on a root-compromised machine. > > > > And in theory a kernel could provide *some* guarantees against root, > > right? (Is there some reason a unix-like kernel must provide such > > things as /dev/kmem?) > > /dev/kmem was just an example -- IMHO differentiating between kernel and > userspace from a security p.o.v. is always tricky. Like Trond said, there > are very high number of ways in which privileged userspace can compromise > a running kernel if it really wants to do that, root-is-God has always ^^^^^^^^^^^^^^
Oh and btw, note that we're talking of the (lack of) security of a "running kernel" here -- because across reboots, there is /really/ *absolutely* no such thing as "kernelspace security" because the superuser will simply switch the vmlinuz itself ... > been *the* major problem with Unix :-) > > The only _real_ way a kernel can lock itself completely against malicious > userspace involves trusted tamperproof hardware, but even that only if > you can get yourself to believe such a thing exists in the first place ;-) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/