The command is not present in the docs/grub.texi user documentation.
Reported-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Patch-Name: 2021-02-security/013-docs-Document-the-cutmem-command.patch
There are some more commands that should be restricted when the GRUB is
locked down. Following is the list of commands and reasons to restrict:
* fakebios: creates BIOS-like structures for backward compatibility with
existing OSes. This should not be allowed when locked down.
* loadbios: reads a BIOS dump from storage and loads it. This action
should not be allowed when locked down.
* devicetree: loads a Device Tree blob and passes it to the OS. It replaces
any Device Tree provided by the firmware. This also should
not be allowed when locked down.
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Patch-Name: 2021-02-security/008-commands-Restrict-commands-that-can-load-BIOS-or-DT-blobs-when-locked-down.patch
The cutmem and badram commands can be used to remove EFI memory regions
and potentially disable the UEFI Secure Boot. Prevent the commands to be
registered if the GRUB is locked down.
Fixes: CVE-2020-27779
Reported-by: Teddy Reed <teddy.reed@gmail.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Patch-Name: 2021-02-security/007-mmap-Don-t-register-cutmem-and-badram-commands-when-lockdown-is-enforced.patch
The command is not allowed when lockdown is enforced. Otherwise an
attacker can instruct the GRUB to load an SSDT table to overwrite
the kernel lockdown configuration and later load and execute
unsigned code.
Fixes: CVE-2020-14372
Reported-by: Máté Kukri <km@mkukri.xyz>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Patch-Name: 2021-02-security/006-acpi-Don-t-register-the-acpi-command-when-locked-down.patch
Now the GRUB can check if it has been locked down and this can be used to
prevent executing commands that can be utilized to circumvent the UEFI
Secure Boot mechanisms. So, instead of hardcoding a list of modules that
have to be disabled, prevent the usage of commands that can be dangerous.
This not only allows the commands to be disabled on other platforms, but
also properly separate the concerns. Since the shim_lock verifier logic
should be only about preventing to run untrusted binaries and not about
defining these kind of policies.
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Patch-Name: 2021-02-security/005-efi-Use-grub_is_lockdown-instead-of-hardcoding-a-disabled-modules-list.patch
It may be useful for scripts to determine whether the GRUB is locked
down or not. Add the lockdown variable which is set to "y" when the GRUB
is locked down.
Suggested-by: Dimitri John Ledkov <xnox@ubuntu.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Patch-Name: 2021-02-security/003-kern-lockdown-Set-a-variable-if-the-GRUB-is-locked-down.patch
When the GRUB starts on a secure boot platform, some commands can be
used to subvert the protections provided by the verification mechanism and
could lead to booting untrusted system.
To prevent that situation, allow GRUB to be locked down. That way the code
may check if GRUB has been locked down and further restrict the commands
that are registered or what subset of their functionality could be used.
The lockdown support adds the following components:
* The grub_lockdown() function which can be used to lockdown GRUB if,
e.g., UEFI Secure Boot is enabled.
* The grub_is_lockdown() function which can be used to check if the GRUB
was locked down.
* A verifier that flags OS kernels, the GRUB modules, Device Trees and ACPI
tables as GRUB_VERIFY_FLAGS_DEFER_AUTH to defer verification to other
verifiers. These files are only successfully verified if another registered
verifier returns success. Otherwise, the whole verification process fails.
For example, PE/COFF binaries verification can be done by the shim_lock
verifier which validates the signatures using the shim_lock protocol.
However, the verification is not deferred directly to the shim_lock verifier.
The shim_lock verifier is hooked into the verification process instead.
* A set of grub_{command,extcmd}_lockdown functions that can be used by
code registering command handlers, to only register unsafe commands if
the GRUB has not been locked down.
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Patch-Name: 2021-02-security/002-kern-Add-lockdown-support.patch
This allows the controversial "recovery mode" text to be customised.
Bug-Ubuntu: https://bugs.launchpad.net/bugs/1240360
Forwarded: no
Last-Update: 2013-12-25
Patch-Name: mkconfig-recovery-title.patch
If other operating systems are installed, then automatically unhide the
menu. Otherwise, if GRUB_HIDDEN_TIMEOUT is 0, then use keystatus if
available to check whether Shift is pressed. If it is, show the menu,
otherwise boot immediately. If keystatus is not available, then fall
back to a short delay interruptible with Escape.
This may or may not remain Ubuntu-specific, although it's not obviously
wanted upstream. It implements a requirement of
https://wiki.ubuntu.com/DesktopExperienceTeam/KarmicBootExperienceDesignSpec#Bootloader.
If the previous boot failed (defined as failing to get to the end of one
of the normal runlevels), then show the boot menu regardless.
Author: Richard Laager <rlaager@wiktel.com>
Author: Robie Basak <robie.basak@ubuntu.com>
Forwarded: no
Last-Update: 2015-09-04
Patch-Name: quick-boot.patch
This is kind of a mess, requiring lots of OS-specific code to iterate
over all possible devices. However, we use it in a number of scripts to
discover devices and reimplementing those in terms of something else
would be very complicated.
Author: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Forwarded: no
Last-Update: 2019-05-25
Patch-Name: restore-mkdevicemap.patch
Add a description of the workaround for firmware of older MacBooks
which stalls with a grub-mkrescue ISO image for x86_64-efi target
on an USB stick.
Signed-off-by: Thomas Schmitt <scdbackup@gmx.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Some older distros do not contain gettext 0.18. Document the workaround
to use the bootstrap utility on these systems.
Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Current comments forms are annoying, so, some of them are disallowed
starting from now. New rules are more flexible and mostly aligned
with, e.g., Linux kernel comments rules.
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Vladimir Serbinenko <phcoder@google.com>
In order to be able to read from and write to model-specific registers,
two new modules are added. They are i386 specific, as the cpuid module.
rdmsr module registers the command rdmsr that allows reading from a MSR.
wrmsr module registers the command wrmsr that allows writing to a MSR.
wrmsr module is disabled if UEFI secure boot is enabled.
Please note that on SMP systems, interacting with a MSR that has a scope
per hardware thread, implies that the value only applies to the
particular cpu/core/thread that ran the command.
Also, if you specify a reserved or unimplemented MSR address, it will
cause a general protection exception (which is not currently being
handled) and the system will reboot.
Signed-off-by: Jesús Diéguez Fernández <jesusdf@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Upgrade Gnulib files to 20190105.
It's much easier to maintain GRUB's use of portability support files
from Gnulib when the process is automatic and driven by a single
configuration file, rather than by maintainers occasionally running
gnulib-tool and committing the result. Removing these
automatically-copied files from revision control also removes the
temptation to hack the output in ways that are difficult for future
maintainers to follow. Gnulib includes a "bootstrap" program which is
designed for this.
The canonical way to bootstrap GRUB from revision control is now
"./bootstrap", but "./autogen.sh" is still useful if you just want to
generate the GRUB-specific parts of the build system.
GRUB now requires Autoconf >= 2.63 and Automake >= 1.11, in line with
Gnulib.
Gnulib source code is now placed in grub-core/lib/gnulib/ (which should
not be edited directly), and GRUB's patches are in
grub-core/lib/gnulib-patches/. I've added a few notes to the developer
manual on how to maintain this.
Signed-off-by: Colin Watson <cjwatson@ubuntu.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Describe the behaviour of GRUB when the TPM module is in use.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This module provides shim lock verification for various kernels
if UEFI secure boot is enabled on a machine.
It is recommended to put this module into GRUB2 standalone image
(avoid putting iorw and memrw modules into it; they are disallowed
if UEFI secure boot is enabled). However, it is also possible to use
it as a normal module. Though such configurations are more fragile
and less secure due to various limitations.
If the module is loaded and UEFI secure boot is enabled then:
- module itself cannot be unloaded (persistent module),
- the iorw and memrw modules cannot be loaded,
- if the iorw and memrw modules are loaded then
machine boot is disabled,
- GRUB2 defers modules and ACPI tables verification to
other verifiers.
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Ross Philipson <ross.philipson@oracle.com>
Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Ross Philipson <ross.philipson@oracle.com>
Update grub-mkconfig.in and 10_linux.in to support grub-probe's new
partuuid target. Update grub.texi documentation. The following table
shows how GRUB_DISABLE_LINUX_UUID, GRUB_DISABLE_LINUX_PARTUUID, and
initramfs detection interact:
Initramfs GRUB_DISABLE_LINUX_PARTUUID GRUB_DISABLE_LINUX_UUID Linux Root
detected Set Set ID Method
false false false part UUID
false false true part UUID
false true false dev name
false true true dev name
true false false fs UUID
true false true part UUID
true true false fs UUID
true true true dev name
Note: GRUB_DISABLE_LINUX_PARTUUID and GRUB_DISABLE_LINUX_UUID equate to
'false' when unset or set to any value other than 'true'.
GRUB_DISABLE_LINUX_PARTUUID defaults to 'true'.
Signed-off-by: Nicholas Vinson <nvinson234@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
"F2FS (Flash-Friendly File System) is flash-friendly file system which was merged
into Linux kernel v3.8 in 2013.
The motive for F2FS was to build a file system that from the start, takes into
account the characteristics of NAND flash memory-based storage devices (such as
solid-state disks, eMMC, and SD cards).
F2FS was designed on a basis of a log-structured file system approach, which
remedies some known issues of the older log structured file systems, such as
the snowball effect of wandering trees and high cleaning overhead. In addition,
since a NAND-based storage device shows different characteristics according to
its internal geometry or flash memory management scheme (such as the Flash
Translation Layer or FTL), it supports various parameters not only for
configuring on-disk layout, but also for selecting allocation and cleaning
algorithm.", quote by https://en.wikipedia.org/wiki/F2FS.
The source codes for F2FS are available from:
http://git.kernel.org/cgit/linux/kernel/git/jaegeuk/f2fs.githttp://git.kernel.org/cgit/linux/kernel/git/jaegeuk/f2fs-tools.git
This patch has been integrated in OpenMandriva Lx 3.
https://www.openmandriva.org/
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Pete Batard <pete@akeo.ie>
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Add support for multiple, shared, early initrd images. These early
images will be loaded in the order declared, and all will be loaded
before the initrd image.
While many classes of data can be provided by early images, the
immediate use case would be for distributions to provide CPU
microcode to mitigate the Meltdown and Spectre vulnerabilities.
There are two environment variables provided for declaring the early
images.
* GRUB_EARLY_INITRD_LINUX_STOCK is for the distribution declare
images that are provided by the distribution or installed packages.
If undeclared, this will default to a set of common microcode image
names.
* GRUB_EARLY_INITRD_LINUX_CUSTOM is for user created images. User
images will be loaded after the stock images.
These separate configurations allow the distribution and user to
declare different image sets without clobbering each other.
This also makes a minor update to ensure that UUID partition labels
stay disabled when no initrd image is found, even if early images are
present.
This is a continuation of a previous patch published by Christian
Hesse in 2016:
http://lists.gnu.org/archive/html/grub-devel/2016-02/msg00025.html
Down stream Gentoo bug:
https://bugs.gentoo.org/645088
Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>
Signed-off-by: Matthew S. Turnbull <sparky@bluefang-logic.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
delete: xen_linux, xen_initrd, xen_xsm
add: xen_module
This update bases on
commit 0edd750e50
Author: Vladimir Serbinenko <phcoder@gmail.com>
Date: Fri Jan 22 10:18:47 2016 +0100
xen_boot: Remove obsolete module type distinctions.
Also bases on the module loading mechanism of Xen code:
488c2a8 docs/arm64: clarify the documention for loading XSM support
67831c4 docs/arm64: update the documentation for loading XSM support
ca32012 xen/arm64: check XSM Magic from the second unknown module.
Signed-off-by: Fu Wei <fu.wei@linaro.org>
Reviewed-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
The current documentation for the special environment variable
"default" is confusing and unclear. This patch attempts to clean it
up.
In particular, the current documentation refers to the "number or
title", but then in the example it gives, the menu entries and
submenus all have numbers *in* their title; furthermore, there is no
example given about how to choose the number, or any indication about
whether counting is zero-indexed or 1-indexed.
Having a cleaner example and presenting all variants (numeric, title,
and id) should make it clearer to the user.
Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
Network boot autoconfiguration sets default server to next server IP
(siaddr) from BOOTP/DHCP reply, but manual configuration using net_bootp
exports only server name. Unfortunately semantic of server name is not
clearly defined. BOOTP RFC 951 defines it only for client request, and
DHCP RFC 1541 only mentions it, without any implied usage. It looks like
this field is mostly empty in server replies.
Export next server IP as net_<interface>_next_server variable. This allows
grub configuration script to set $root/$prefix based on information obtained
by net_bootp.
Reported and tested by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Cc: nikunj@linux.vnet.ibm.com
v2: change variable name to net_<interface>_next_server as discussed on the list
superusers controls both CLI and editing. Also explicitly mention that
empty superusers disables them.
"Access to menuentry" is a bit vague - change to "execute menuentry"
to make it obvious, what access is granted.
From RFC1542:
The 'giaddr' field is rather poorly named. It exists to facilitate
the transfer of BOOTREQUEST messages from a client, through BOOTP
relay agents, to servers on different networks than the client.
Similarly, it facilitates the delivery of BOOTREPLY messages from the
servers, through BOOTP relay agents, back to the client. In no case
does it represent a general IP router to be used by the client. A
BOOTP client MUST set the 'giaddr' field to zero (0.0.0.0) in all
BOOTREQUEST messages it generates.
A BOOTP client MUST NOT interpret the 'giaddr' field of a BOOTREPLY
message to be the IP address of an IP router. A BOOTP client SHOULD
completely ignore the contents of the 'giaddr' field in BOOTREPLY
messages.
Leave code ifdef'd out for the time being in case we see regression.
Suggested by: Rink Springer <rink@rink.nu>
Closes: 43396
