On Thu, 30 Aug 2007, J. Bruce Fields wrote:
> On Thu, Aug 30, 2007 at 11:04:00AM -0400, Trond Myklebust wrote: > > With CIFS or other password based protocols (including RPCSEC_GSS) > > Well, rpcsec_gss isn't inherently password based, and you can > authenticate in some way that doesn't actually give away your password > (or other long-lived credential). > > > 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 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 ;-) Satyam - 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/
