110 Commits

Author SHA1 Message Date
Glenn Washburn
dcc1af5d68 efi: Generate stack protector canary at build time if urandom is available
Generating the canary at build time allows the canary to be different for
every build which could limit the effectiveness of certain exploits.
Fallback to the statically generated random bytes if /dev/urandom is not
readable, e.g. Windows.

On 32-bit architectures, which use a 32-bit canary, reduce the canary to
4 bytes with one byte being NUL to filter out string buffer overflow attacks.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-12-20 14:31:50 +01:00
Glenn Washburn
e424e945c9 efi: Initialize canary to non-zero value
The canary, __stack_chk_guard, is in the BSS and so will get initialized to
zero if it is not explicitly initialized. If the UEFI firmware does not
support the RNG protocol, then the canary will not be randomized and will
be zero. This seems like a possibly easier value to write by an attacker.
Initialize canary to static random bytes, so that it is still random when
there is no RNG protocol. Set at least one byte to NUL to protect against
string buffer overflow attacks [1]. Code that writes NUL terminated strings
will terminate when a NUL is encountered in the input byte stream. So the
attacker will not be able to forge the canary by including it in the input
stream without terminating the string operation and thus limiting the
stack corruption.

[1] https://www.sans.org/blog/stack-canaries-gingerly-sidestepping-the-cage/

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-12-20 14:17:23 +01:00
Julian Andres Klode
e60015f574 efi: Set shim_lock_enabled even if validation is disabled
If validation has been disabled via MokSbState, secure boot on the
firmware is still enabled, and the kernel fails to boot.

This is a bit hacky, because shim_lock is not *fully* enabled, but
it triggers the right code paths.

Ultimately, all this will be resolved by shim gaining it's own image
loading and starting protocol, so this is more a temporary workaround.

Fixes: 6425c12cd (efi: Fallback to legacy mode if shim is loaded on x86 archs)

Cc: Peter Jones <pjones@redhat.com>
Cc: Michael Chang <mchang@suse.com>
Signed-off-by: Julian Andres Klode <julian.klode@canonical.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-12-05 15:28:39 +01:00
Vladimir Serbinenko
7de6fe9635 types: Split aligned and packed guids
On ia64 alignment requirements are strict. When we pass a pointer to
UUID it needs to be at least 4-byte aligned or EFI will crash.
On the other hand in device path there is no padding for UUID, so we
need 2 types in one formor another. Make 4-byte aligned and unaligned types

The code is structured in a way to accept unaligned inputs
in most cases and supply 4-byte aligned outputs.

Efiemu case is a bit ugly because there inputs and outputs are
reversed and so we need careful casts to account for this
inversion.

Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-11-08 05:04:24 +01:00
Vladimir Serbinenko
7ad30299da efi: Deduplicate configuration table search function
We do table search in many places doing exactly the same algorithm.
The only minor variance in users is which table is used if several entries
are present. As specification mandates uniqueness and even if it ever isn't,
first entry is good enough, unify this code and always use the first entry.

Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-11-06 22:47:16 +01:00
Glenn Washburn
c3bdf263f6 kern/efi/init: Disable stack smashing protection on grub_efi_init()
GCC is electing to instrument grub_efi_init() to give it stack smashing
protection when configuring with --enable-stack-protector on the x86_64-efi
target. In the function prologue, the canary at the top of the stack frame
is set to the value of the stack guard. And in the epilogue, the canary is
checked to verify if it is equal to the guard and if not to call the stack
check fail function. The issue is that grub_efi_init() sets up the guard
by initializing it with random bytes, if the firmware supports the RNG
protocol. So in its prologue the canary will be set with the value of the
uninitialized guard, likely NUL bytes. Then the guard is initialized, and
finally the epilogue checks the canary against the guard, which will almost
certainly be different. This causes the code path for a smashed stack to be
taken, causing the machine to print out a message that stack smashing was
detected, wait 5 seconds, and then reboot. Disable grub_efi_init()
instrumentation so there is no stack smashing false positive generated.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-10-12 17:47:28 +02:00
Daniel Kiper
6425c12cd7 efi: Fallback to legacy mode if shim is loaded on x86 archs
The LoadImage() provided by the shim does not consult MOK when loading
an image. So, simply signature verification fails when it should not.
This means we cannot use Linux EFI stub to start the kernel when the
shim is loaded. We have to fallback to legacy mode on x86 architectures.
This is not possible on other architectures due to lack of legacy mode.

This is workaround which should disappear when the shim provides
LoadImage() which looks up MOK during signature verification.

On the occasion align constants in include/grub/efi/sb.h.

Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
2023-07-03 14:29:22 +02:00
Glenn Washburn
c016a969d1 gdb: Add gdbinfo command for printing the load address of the EFI application
EFI firmware determines where to load the GRUB EFI at runtime, and so the
addresses of debug symbols are not known ahead of time. There is a command
defined in the gdb_grub script which will load the debug symbols at the
appropriate addresses, if given the application load address for GRUB.
So add a command named "gdbinfo" to allow the user to print this GDB command
string with the application load address on-demand. For the outputted GDB
command to have any effect when entered into a GDB session, GDB should have
been started with the script as an argument to the -x option or sourced into
an active GDB session before running the outputted command.

Documentation for the gdbinfo command is also added.

Co-developed-by: Peter Jones <pjones@redhat.com>
Signed-off-by: Peter Jones <pjones@redhat.com>
Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-06-01 12:10:04 +02:00
Oliver Steffen
e83a88f6ea efi: Add grub_efi_set_variable_to_string()
Add a function that sets an EFI variable to a string value.
The string is converted from UTF-8 to UTF-16.

Signed-off-by: Oliver Steffen <osteffen@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-06-01 11:45:00 +02:00
Oliver Steffen
a0b16564ee kern/misc, kern/efi: Extract UTF-8 to UTF-16 code
Create a new function for UTF-8 to UTF-16 conversion called
grub_utf8_to_utf16_alloc() in the grub-code/kern/misc.c and replace
charset conversion code used in some places in the EFI code. It is
modeled after the grub_utf8_to_ucs4_alloc() like functions in
include/grub/charset.h. It can't live in include/grub/charset.h,
because it needs to be reachable from the kern/efi code.

Add a check for integer overflow and remove redundant NUL-termination.

Signed-off-by: Oliver Steffen <osteffen@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-06-01 11:45:00 +02:00
Oliver Steffen
6ad116e5ff guid: Make use of GUID printf format specifier
Use the new printf format specifier %pG.

Fixes the text representation of GUIDs in the output of the lsefisystab
command (missing 4th dash).

Signed-off-by: Oliver Steffen <osteffen@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-06-01 11:45:00 +02:00
Oliver Steffen
06edd40db7 guid: Unify GUID types
There are 3 implementations of a GUID in GRUB. Replace them with
a common one, placed in types.h.

It uses the "packed" flavor of the GUID structs, the alignment attribute
is dropped, since it is not required.

Signed-off-by: Oliver Steffen <osteffen@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-06-01 11:45:00 +02:00
Oliver Steffen
7e4da6fb2d efi: Add grub_efi_set_variable_with_attributes()
Add a function to the EFI module that allows setting EFI variables
with specific attributes.

This is useful for marking variables as volatile, for example.

Signed-off-by: Oliver Steffen <osteffen@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-06-01 11:43:25 +02:00
Alec Brown
6f05a27796 kern/efi/mm: Fix use-after-free in finish boot services
In grub-core/kern/efi/mm.c, grub_efi_finish_boot_services() has an instance
where the memory for the variable finish_mmap_buf is freed, but on the next
iteration of a while loop, grub_efi_get_memory_map() uses finish_mmap_buf. To
prevent this, we can set finish_mmap_buf to NULL after the free.

Signed-off-by: Alec Brown <alec.r.brown@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-05-25 16:48:00 +02:00
Ard Biesheuvel
bb4aa6e06e efi: Drop all uses of efi_call_XX() wrappers
Now that GCC can generate function calls using the correct calling
convention for us, we can stop using the efi_call_XX() wrappers, and
just dereference the function pointers directly.

This avoids the untyped variadic wrapper routines, which means better
type checking for the method calls.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-05-25 16:48:00 +02:00
Xiaotian Wu
d33cbf2d8f loongarch: Add auxiliary files
Add support for manipulating architectural cache and timers, and EFI
memory maps.

Signed-off-by: Zhou Yang <zhouyang@loongson.cn>
Signed-off-by: Xiaotian Wu <wuxiaotian@loongson.cn>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2023-05-17 13:21:43 +02:00
Zhang Boyang
93a786a001 kern/efi/sb: Enforce verification of font files
As a mitigation and hardening measure enforce verification of font
files. Then only trusted font files can be load. This will reduce the
attack surface at cost of losing the ability of end-users to customize
fonts if e.g. UEFI Secure Boot is enabled. Vendors can always customize
fonts because they have ability to pack fonts into their GRUB bundles.

This goal is achieved by:

  * Removing GRUB_FILE_TYPE_FONT from shim lock verifier's
    skip-verification list.

  * Adding GRUB_FILE_TYPE_FONT to lockdown verifier's defer-auth list,
    so font files must be verified by a verifier before they can be loaded.

Suggested-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2022-11-14 20:24:39 +01:00
Ard Biesheuvel
6d7bb89efa efi: Move MS-DOS stub out of generic PE header definition
The PE/COFF spec permits the COFF signature and file header to appear
anywhere in the file, and the actual offset is recorded in 4 byte
little endian field at offset 0x3c of the image.

When GRUB is emitted as a PE/COFF binary, we reuse the 128 byte MS-DOS
stub (even for non-x86 architectures), putting the COFF signature and
file header at offset 0x80. However, other PE/COFF images may use
different values, and non-x86 Linux kernels use an offset of 0x40
instead.

So let's get rid of the grub_pe32_header struct from pe32.h, given that
it does not represent anything defined by the PE/COFF spec. Instead,
introduce a minimal struct grub_msdos_image_header type based on the
PE/COFF spec's description of the image header, and use the offset
recorded at file position 0x3c to discover the actual location of the PE
signature and the COFF image header.

The remaining fields are moved into a struct grub_pe_image_header,
which we will use later to access COFF header fields of arbitrary
images (and which may therefore appear at different offsets)

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2022-10-27 16:53:01 +02:00
Daniel Axtens
75e38e86e7 efi: Increase default memory allocation to 32 MiB
We have multiple reports of things being slower with a 1 MiB initial static
allocation, and a report (more difficult to nail down) of a boot failure
as a result of the smaller initial allocation.

Make the initial memory allocation 32 MiB.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2022-10-04 17:06:25 +02:00
Robbie Harwood
dbc641ac92 efi: Make all grub_efi_guid_t variables static
This is believed to result in smaller code.

Signed-off-by: Robbie Harwood <rharwood@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2022-08-20 00:23:11 +02:00
Patrick Steinhardt
1df2934822 kern/efi/mm: Implement runtime addition of pages
Adjust the interface of grub_efi_mm_add_regions() to take a set of
GRUB_MM_ADD_REGION_* flags, which most notably is currently only the
GRUB_MM_ADD_REGION_CONSECUTIVE flag. This allows us to set the function
up as callback for the memory subsystem and have it call out to us in
case there's not enough pages available in the current heap.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Patrick Steinhardt <ps@pks.im>
2022-07-04 14:43:17 +02:00
Patrick Steinhardt
15a0156989 kern/efi/mm: Pass up errors from add_memory_regions()
The function add_memory_regions() is currently only called on system
initialization to allocate a fixed amount of pages. As such, it didn't
need to return any errors: in case it failed, we cannot proceed anyway.
This will change with the upcoming support for requesting more memory
from the firmware at runtime, where it doesn't make sense anymore to
fail hard.

Refactor the function to return an error to prepare for this. Note that
this does not change the behaviour when initializing the memory system
because grub_efi_mm_init() knows to call grub_fatal() in case
grub_efi_mm_add_regions() returns an error.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Patrick Steinhardt <ps@pks.im>
2022-07-04 14:38:57 +02:00
Patrick Steinhardt
96a7ea29e3 kern/efi/mm: Extract function to add memory regions
In preparation of support for runtime-allocating additional memory
region, this patch extracts the function to retrieve the EFI memory
map and add a subset of it to GRUB's own memory regions.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Patrick Steinhardt <ps@pks.im>
2022-07-04 14:36:15 +02:00
Patrick Steinhardt
938c3760b8 kern/efi/mm: Always request a fixed number of pages on init
When initializing the EFI memory subsystem, we will by default request
a quarter of the available memory, bounded by a minimum/maximum value.
Given that we're about to extend the EFI memory system to dynamically
request additional pages from the firmware as required, this scaling of
requested memory based on available memory will not make a lot of sense
anymore.

Remove this logic as a preparatory patch such that we'll instead defer
to the runtime memory allocator. Note that ideally, we'd want to change
this after dynamic requesting of pages has been implemented for the EFI
platform. But because we'll need to split up initialization of the
memory subsystem and the request of pages from the firmware, we'd have
to duplicate quite some logic at first only to remove it afterwards
again. This seems quite pointless, so we instead have patches slightly
out of order.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Patrick Steinhardt <ps@pks.im>
2022-07-04 14:25:41 +02:00
Julian Andres Klode
6fe755c5c0 kern/efi/sb: Reject non-kernel files in the shim_lock verifier
We must not allow other verifiers to pass things like the GRUB modules.
Instead of maintaining a blocklist, maintain an allowlist of things
that we do not care about.

This allowlist really should be made reusable, and shared by the
lockdown verifier, but this is the minimal patch addressing
security concerns where the TPM verifier was able to mark modules
as verified (or the OpenPGP verifier for that matter), when it
should not do so on shim-powered secure boot systems.

Fixes: CVE-2022-28735

Signed-off-by: Julian Andres Klode <julian.klode@canonical.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2022-06-07 16:39:31 +02:00
Chad Kimes
c143056a34 kern/efi/efi: Print VLAN info in EFI device path
Signed-off-by: Chad Kimes <chkimes@github.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2022-04-20 13:58:13 +02:00
Chris Coulson
37ddd9457f kern/efi/init: Log a console error during a stack check failure
The initial implementation of the stack protector just busy looped
in __stack_chk_fail in order to reduce the amount of code being
executed after the stack has been compromised because of a lack of
firmware memory protections. With future firmware implementations
incorporating memory protections such as W^X, call in to boot services
when an error occurs in order to log a message to the console before
automatically rebooting the machine.

Signed-off-by: Chris Coulson <chris.coulson@canonical.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2022-04-04 22:26:31 +02:00
Elyes Haouas
edd9af9192 kern: Remove trailing whitespaces
Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2022-03-14 15:46:55 +01:00
Heinrich Schuchardt
d0219bffc7 efi: Create the grub_efi_close_protocol() library function
Create a library function for CloseProtocol() and use it for the SNP driver.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2021-12-23 01:33:13 +01:00
Tianjia Zhang
f17e8b9ed2 kern/efi/sb: Remove duplicate efi_shim_lock_guid variable
The efi_shim_lock_guid local variable and shim_lock_guid global variable
have the same GUID value. Only the latter is retained.

Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2021-05-28 12:49:56 +02:00
Daniel Kiper
66be067e61 i18n: Format large integers before the translation message - take 2
This is an additional fix which has been missing from the commit 837fe48de
(i18n: Format large integers before the translation message).

Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
2021-05-10 15:06:33 +02:00
Glenn Washburn
e2ac93f09a kern/efi/mm: Format string error in grub_error()
The second format string argument, GRUB_EFI_MAX_USABLE_ADDRESS, is a macro
to a number literal. However, depending on what the target architecture, the
type can be 32 or 64 bits. Cast to a 64-bit integer. Also, change the
format string literals "%llx" to use PRIxGRUB_UINT64_T.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2021-03-10 14:56:06 +01:00
Glenn Washburn
e96c7645f4 grub_error: Use format code PRIuGRUB_SIZE for variables of type grub_size_t
Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2021-03-10 14:50:44 +01:00
Michael Chang
6d05264eec kern/efi/sb: Add chainloaded image as shim's verifiable object
While attempting to dual boot Microsoft Windows with UEFI chainloader,
it failed with below error when UEFI Secure Boot was enabled:

  error ../../grub-core/kern/verifiers.c:119:verification requested but
  nobody cares: /EFI/Microsoft/Boot/bootmgfw.efi.

It is a regression, as previously it worked without any problem.

It turns out chainloading PE image has been locked down by commit
578c95298 (kern: Add lockdown support). However, we should consider it
as verifiable object by shim to allow booting in UEFI Secure Boot mode.
The chainloaded PE image could also have trusted signature created by
vendor with their pubkey cert in db. For that matters it's usage should
not be locked down under UEFI Secure Boot, and instead shim should be
allowed to validate a PE binary signature before running it.

Fixes: 578c95298 (kern: Add lockdown support)

Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2021-03-10 13:49:42 +01:00
Dimitri John Ledkov
968de8c23c shim_lock: Only skip loading shim_lock verifier with explicit consent
Commit 32ddc42c (efi: Only register shim_lock verifier if shim_lock
protocol is found and SB enabled) reintroduced CVE-2020-15705 which
previously only existed in the out-of-tree linuxefi patches and was
fixed as part of the BootHole patch series.

Under Secure Boot enforce loading shim_lock verifier. Allow skipping
shim_lock verifier if SecureBoot/MokSBState EFI variables indicate
skipping validations, or if GRUB image is built with --disable-shim-lock.

Fixes: 132ddc42c (efi: Only register shim_lock verifier if shim_lock
       protocol is found and SB enabled)
Fixes: CVE-2020-15705
Fixes: CVE-2021-3418

Reported-by: Dimitri John Ledkov <xnox@ubuntu.com>
Signed-off-by: Dimitri John Ledkov <xnox@ubuntu.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2021-03-02 15:54:19 +01:00
Chris Coulson
133d73079c kern/efi: Add initial stack protector implementation
It works only on UEFI platforms but can be quite easily extended to
others architectures and platforms if needed.

Signed-off-by: Chris Coulson <chris.coulson@canonical.com>
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Marco A Benatto <mbenatto@redhat.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
2021-03-02 15:54:19 +01:00
Darren Kenny
6aee4bfd69 kern/efi/mm: Fix possible NULL pointer dereference
The model of grub_efi_get_memory_map() is that if memory_map is NULL,
then the purpose is to discover how much memory should be allocated to
it for the subsequent call.

The problem here is that with grub_efi_is_finished set to 1, there is no
check at all that the function is being called with a non-NULL memory_map.

While this MAY be true, we shouldn't assume it.

The solution to this is to behave as expected, and if memory_map is NULL,
then don't try to use it and allow memory_map_size to be filled in, and
return 0 as is done later in the code if the buffer is too small (or NULL).

Additionally, drop unneeded ret = 1.

Fixes: CID 96632

Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2021-03-02 15:54:16 +01:00
Darren Kenny
ed286ceba6 kern/efi: Fix memory leak on failure
Free the memory allocated to name before returning on failure.

Fixes: CID 296222

Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2021-03-02 15:54:16 +01:00
Javier Martinez Canillas
8f73052885 efi: Use grub_is_lockdown() instead of hardcoding a disabled modules list
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>
2021-03-02 15:54:15 +01:00
Javier Martinez Canillas
98b00a403c efi: Lockdown the GRUB when the UEFI Secure Boot is enabled
If the UEFI Secure Boot is enabled then the GRUB must be locked down
to prevent executing code that can potentially be used to subvert its
verification mechanisms.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2021-03-02 15:54:15 +01:00
Marco A Benatto
5e280caa65 efi: Move the shim_lock verifier to the GRUB core
Move the shim_lock verifier from its own module into the core image. The
Secure Boot lockdown mechanism has the intent to prevent the load of any
unsigned code or binary when Secure Boot is enabled.

The reason is that GRUB must be able to prevent executing untrusted code
if UEFI Secure Boot is enabled, without depending on external modules.

Signed-off-by: Marco A Benatto <mbenatto@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2021-03-02 15:54:15 +01:00
Daniel Kiper
d7e54b2e5f efi: Add secure boot detection
Introduce grub_efi_get_secureboot() function which returns whether
UEFI Secure Boot is enabled or not on UEFI systems.

Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Marco A Benatto <mbenatto@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-12-11 13:56:22 +01:00
Daniel Kiper
ac5c936754 efi: Add a function to read EFI variables with attributes
It will be used to properly detect and report UEFI Secure Boot status to
the x86 Linux kernel. The functionality will be added by subsequent patches.

Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Marco A Benatto <mbenatto@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-12-11 13:55:31 +01:00
Daniel Kiper
04ae030d0e efi: Return grub_efi_status_t from grub_efi_get_variable()
This is needed to properly detect and report UEFI Secure Boot status
to the x86 Linux kernel. The functionality will be added by subsequent
patches.

Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Marco A Benatto <mbenatto@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-12-11 13:54:54 +01:00
Alexey Makhalov
f7bd9986f6 efi: Fix use-after-free in halt/reboot path
commit 92bfc33db984 ("efi: Free malloc regions on exit")
introduced memory freeing in grub_efi_fini(), which is
used not only by exit path but by halt/reboot one as well.
As result of memory freeing, code and data regions used by
modules, such as halt, reboot, acpi (used by halt) also got
freed. After return to module code, CPU executes, filled
by UEFI firmware (tested with edk2), 0xAFAFAFAF pattern as
a code. Which leads to #UD exception later.

grub> halt
!!!! X64 Exception Type - 06(#UD - Invalid Opcode)  CPU Apic ID - 00000000 !!!!
RIP  - 0000000003F4EC28, CS  - 0000000000000038, RFLAGS - 0000000000200246
RAX  - 0000000000000000, RCX - 00000000061DA188, RDX - 0A74C0854DC35D41
RBX  - 0000000003E10E08, RSP - 0000000007F0F860, RBP - 0000000000000000
RSI  - 00000000064DB768, RDI - 000000000832C5C3
R8   - 0000000000000002, R9  - 0000000000000000, R10 - 00000000061E2E52
R11  - 0000000000000020, R12 - 0000000003EE5C1F, R13 - 00000000061E0FF4
R14  - 0000000003E10D80, R15 - 00000000061E2F60
DS   - 0000000000000030, ES  - 0000000000000030, FS  - 0000000000000030
GS   - 0000000000000030, SS  - 0000000000000030
CR0  - 0000000080010033, CR2 - 0000000000000000, CR3 - 0000000007C01000
CR4  - 0000000000000668, CR8 - 0000000000000000
DR0  - 0000000000000000, DR1 - 0000000000000000, DR2 - 0000000000000000
DR3  - 0000000000000000, DR6 - 00000000FFFF0FF0, DR7 - 0000000000000400
GDTR - 00000000079EEA98 0000000000000047, LDTR - 0000000000000000
IDTR - 0000000007598018 0000000000000FFF,   TR - 0000000000000000
FXSAVE_STATE - 0000000007F0F4C0

Proposal here is to continue to free allocated memory for
exit boot services path but keep it for halt/reboot path
as it won't be much security concern here.
Introduced GRUB_LOADER_FLAG_EFI_KEEP_ALLOCATED_MEMORY
loader flag to be used by efi halt/reboot path.

Signed-off-by: Alexey Makhalov <amakhalov@vmware.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-07-29 16:55:48 +02:00
Peter Jones
d2cf823d0e efi: Fix some malformed device path arithmetic errors
Several places we take the length of a device path and subtract 4 from
it, without ever checking that it's >= 4. There are also cases where
this kind of malformation will result in unpredictable iteration,
including treating the length from one dp node as the type in the next
node. These are all errors, no matter where the data comes from.

This patch adds a checking macro, GRUB_EFI_DEVICE_PATH_VALID(), which
can be used in several places, and makes GRUB_EFI_NEXT_DEVICE_PATH()
return NULL and GRUB_EFI_END_ENTIRE_DEVICE_PATH() evaluate as true when
the length is too small. Additionally, it makes several places in the
code check for and return errors in these cases.

Signed-off-by: Peter Jones <pjones@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-07-29 16:55:48 +02:00
Peter Jones
f725fa7cb2 calloc: Use calloc() at most places
This modifies most of the places we do some form of:

  X = malloc(Y * Z);

to use calloc(Y, Z) instead.

Among other issues, this fixes:
  - allocation of integer overflow in grub_png_decode_image_header()
    reported by Chris Coulson,
  - allocation of integer overflow in luks_recover_key()
    reported by Chris Coulson,
  - allocation of integer overflow in grub_lvm_detect()
    reported by Chris Coulson.

Fixes: CVE-2020-14308

Signed-off-by: Peter Jones <pjones@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-07-29 16:55:47 +02:00
Peter Jones
df84d6e94c efi: Print error messages to grub_efi_allocate_pages_real()
No messages were printed in this function, add some to ease debugging.

Also, the function returns a void * pointer so return NULL instead of
0 to make the code more readable.

Signed-off-by: Peter Jones <pjones@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-03-10 21:41:16 +01:00
Peter Jones
cc93c5a849 efi: Print more debug info in our module loader
The function that searches the mods section base address does not have
any debug information. Add some debugging outputs that could be useful.

Signed-off-by: Peter Jones <pjones@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-03-10 21:39:44 +01:00
Michael Chang
4dd4ceec02 efi: Fix gcc9 error -Waddress-of-packed-member
The address of fp->path_name could be unaligned since seeking into the
device path buffer for a given node could end in byte boundary.

The fix is allocating aligned buffer by grub_malloc for holding the
UTF16 string copied from fp->path_name, and after using that buffer as
argument for grub_utf16_to_utf8 to convert it to UTF8 string.

[  255s] ../../grub-core/kern/efi/efi.c: In function 'grub_efi_get_filename':
[  255s] ../../grub-core/kern/efi/efi.c:410:60: error: taking address of packed member of 'struct grub_efi_file_path_device_path' may result in an unaligned pointer value [-Werror=address-of-packed-member]
[  255s]   410 |    p = (char *) grub_utf16_to_utf8 ((unsigned char *) p, fp->path_name, len);
[  255s]       |                                                          ~~^~~~~~~~~~~
[  255s] ../../grub-core/kern/efi/efi.c: In function 'grub_efi_print_device_path':
[  255s] ../../grub-core/kern/efi/efi.c:900:33: error: taking address of packed member of 'struct grub_efi_file_path_device_path' may result in an unaligned pointer value [-Werror=address-of-packed-member]
[  255s]   900 |     *grub_utf16_to_utf8 (buf, fp->path_name,
[  255s]       |                               ~~^~~~~~~~~~~

Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2019-04-23 11:37:08 +02:00