From mboxrd@z Thu Jan 1 00:00:00 1970 From: dyoung@redhat.com (Dave Young) Date: Fri, 7 Apr 2017 15:39:56 +0800 Subject: [PATCH 17/24] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down In-Reply-To: <21360.1491548727@warthog.procyon.org.uk> References: <20170407063107.GA10451@dhcp-128-65.nay.redhat.com> <149142326734.5101.4596394505987813763.stgit@warthog.procyon.org.uk> <149142341772.5101.12366553346604485034.stgit@warthog.procyon.org.uk> <21360.1491548727@warthog.procyon.org.uk> Message-ID: <20170407073956.GA10737@dhcp-128-65.nay.redhat.com> To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org On 04/07/17 at 08:05am, David Howells wrote: > Dave Young wrote: > > > > > This option allows userspace to pass the RSDP address to the kernel, which > > > > makes it possible for a user to circumvent any restrictions imposed on > > > > loading modules. Ignore the option when the kernel is locked down. > > > > > > I'm not really sure here. > > > > > > What exactly is the mechanism? > > > > Actually this acpi_rsdp param is created for EFI kexec reboot in old > > days when we had not supported persistent efi vm space across kexec > > reboot. At that time kexec reboot runs as noefi mode, it can not find > > the acpi root table thus kernel will hang early. > > > > Now kexec can support EFI boot so this param is not necessary for most > > user unless they still use efi=old_map. > > Is this patch now unnecessary? I think it is still necessary because the acpi_rsdp kernel param is still a valid paramater and one can still pass a pointer to be recognized as acpi root pointer. Maybe "imposed on loading modules" is not clear which can be dropped. Thanks Dave -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html