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Commit 0f9a1739dd0e ("efi: zboot specific mechanism for embedding SBAT
section") neglected to adjust the sizes of the .data section when
CONFIG_EFI_SBAT_FILE is set. As the result, the produced PE binary is
incorrect and some tools complain about it. E.g. 'sbsign' reports:
# sbsign --key my.key --cert my.crt arch/arm64/boot/vmlinuz.efi
warning: file-aligned section .data extends beyond end of file
warning: checksum areas are greater than image size. Invalid section table?
Note, '__data_size' is also used in the PE optional header and it is not
entirely clear whether .sbat needs to be accounted as part of
SizeOfInitializedData or not. As the header seems to be unused by the real
world firmware, keeping the field equal to __data_size.
Fixes: 0f9a1739dd0e ("efi: zboot specific mechanism for embedding SBAT section")
Reported-by: Heinrich Schuchardt <heinrich.schuchardt@gmx.de>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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Older versions of `ld` don't seem to support preprocessor directives in
linker scripts, e.g. on RHEL9's ld-2.35.2-63.el9 the build fails with:
ld:./drivers/firmware/efi/libstub/zboot.lds:32: ignoring invalid character `#' in expression
ld:./drivers/firmware/efi/libstub/zboot.lds:33: syntax error
We don't seem to need these '#ifdef', no empty .sbat section is created
when CONFIG_EFI_SBAT_FILE="":
# objdump -h arch/arm64/boot/vmlinuz.efi
arch/arm64/boot/vmlinuz.efi: file format pei-aarch64-little
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 00b94000 0000000000001000 0000000000001000 00001000 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .data 00000200 0000000000b95000 0000000000b95000 00b95000 2**2
CONTENTS, ALLOC, LOAD, DATA
Fixes: 0f9a1739dd0e ("efi: zboot specific mechanism for embedding SBAT section")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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SBAT is a mechanism which improves SecureBoot revocations of UEFI binaries
by introducing a generation-based technique. Compromised or vulnerable UEFI
binaries can be prevented from booting by bumping the minimal required
generation for the specific component in the bootloader. More information
on the SBAT can be obtained here:
https://github.com/rhboot/shim/blob/main/SBAT.md
Upstream Linux kernel does not currently participate in any way in SBAT as
there's no existing policy in how SBAT generation number should be
defined. Keep the status quo and provide a mechanism for distro vendors and
anyone else who signs their kernel for SecureBoot to include their own SBAT
data. This leaves the decision on the policy to the vendor. Basically, each
distro implementing SecureBoot today, will have an option to inject their
own SBAT data during kernel build and before it gets signed by their
SecureBoot CA. Different distro do not need to agree on the common SBAT
component names or generation numbers as each distro ships its own 'shim'
with their own 'vendor_cert'/'vendor_db'
Implement support for embedding SBAT data for architectures using
zboot (arm64, loongarch, riscv). Put '.sbat' section in between '.data' and
'.text' as the former also covers '.bss' and thus must be the last one.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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Remove EFI zboot's dependency on the decompression wrappers used by the
legacy decompressor boot code, which can only process the input in one
go, and this will not work for upcoming support for embedded ELF images.
They also do some odd things like providing a barebones malloc()
implementation, which is not needed in a hosted environment such as the
EFI boot services.
So instead, implement GZIP deflate and ZSTD decompression in terms of
the underlying libraries. Support for other compression algoritms has
already been dropped.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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When building ARCH=loongarch defconfig + CONFIG_UNWINDER_ORC=y using
LLVM, there is a warning from ld.lld when linking the EFI zboot image
due to the use of unreachable() in number() in vsprintf.c:
ld.lld: warning: drivers/firmware/efi/libstub/lib.a(vsprintf.stub.o):(.discard.unreachable+0x0): has non-ABS relocation R_LARCH_32_PCREL against symbol ''
If the compiler cannot eliminate the default case for any reason, the
.discard.unreachable section will remain in the final binary but the
entire point of any section prefixed with .discard is that it is only
used at compile time, so it can be discarded via /DISCARD/ in a linker
script. The asm-generic vmlinux.lds.h includes .discard and .discard.*
in the COMMON_DISCARDS macro but that is not used for zboot.lds, as it
is not a kernel image linker script.
Add .discard and .discard.* to /DISCARD/ in zboot.lds, so that any
sections meant to be discarded at link time are not included in the
final zboot image. This issue is not specific to LoongArch, it is just
the first architecture to select CONFIG_OBJTOOL, which defines
annotate_unreachable() as an asm statement to add the
.discard.unreachable section, and use the EFI stub.
Closes: https://github.com/ClangBuiltLinux/linux/issues/2023
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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The EFI zboot code is not built as part of the kernel proper, like the
ordinary EFI stub, but still needs access to symbols that are defined
only internally in the kernel, and are left unexposed deliberately to
avoid creating ABI inadvertently that we're stuck with later.
So capture the kernel code size of the kernel image, and inject it as an
ELF symbol into the object that contains the compressed payload, where
it will be accessible to zboot code that needs it.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
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The linker script symbol definition that captures the size of the
compressed payload inside the zboot decompressor (which is exposed via
the image header) refers to '.' for the end of the region, which does
not give the correct result as the expression is not placed at the end
of the payload. So use the symbol name explicitly.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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Implement a minimal EFI app that decompresses the real kernel image and
launches it using the firmware's LoadImage and StartImage boot services.
This removes the need for any arch-specific hacks.
Note that on systems that have UEFI secure boot policies enabled,
LoadImage/StartImage require images to be signed, or their hashes known
a priori, in order to be permitted to boot.
There are various possible strategies to work around this requirement,
but they all rely either on overriding internal PI/DXE protocols (which
are not part of the EFI spec) or omitting the firmware provided
LoadImage() and StartImage() boot services, which is also undesirable,
given that they encapsulate platform specific policies related to secure
boot and measured boot, but also related to memory permissions (whether
or not and which types of heap allocations have both write and execute
permissions.)
The only generic and truly portable way around this is to simply sign
both the inner and the outer image with the same key/cert pair, so this
is what is implemented here.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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