On Wed, Apr 4, 2018 at 5:57 AM Theodore Y. Ts'o <ty...@mit.edu> wrote:
> On Wed, Apr 04, 2018 at 04:30:18AM +0000, Matthew Garrett wrote: > > What I'm afraid of is this turning into a "security" feature that ends up > > being circumvented in most scenarios where it's currently deployed - eg, > > module signatures are mostly worthless in the non-lockdown case because you > > can just grab the sig_enforce symbol address and then kexec a preamble that > > flips it back to N regardless of the kernel config. > Whoa. Why doesn't lockdown prevent kexec? Put another away, why > isn't this a problem for people who are fearful that Linux could be > used as part of a Windows boot virus in a Secure UEFI context? It does - I was talking about the non-lockdown case. In the lockdown case you can only kexec images you trust, so there's no problem. Red Hat have been shipping a signed kdump image for years.