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Ts'o" , Matthew Garrett , Linus Torvalds , luto@kernel.org, David Howells , Ard Biesheuvel , jmorris@namei.org, Alan Cox , Linux Kernel Mailing List , jforbes@redhat.com, linux-man@vger.kernel.org, jlee@suse.com, LSM List , linux-api@vger.kernel.org, Kees Cook , linux-efi Subject: Re: [GIT PULL] Kernel lockdown for secure boot Message-ID: <20180404130233.GA24008@kroah.com> References: <20180404125743.GB16242@thunk.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180404125743.GB16242@thunk.org> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-api-owner@vger.kernel.org X-Mailing-List: linux-api@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wed, Apr 04, 2018 at 08:57:43AM -0400, Theodore Y. Ts'o 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? Because no one is afraid of that :) greg k-h