[PATCH 00/14] arm64: kexec: add kexec_file_load support

From: AKASHI Takahiro
Date: Thu Aug 24 2017 - 04:19:27 EST

This is the initial attempt of implementing kexec_file_load() support
on arm64.[1]
Most of the code is based on kexec-tools (along with some kernel code
from x86 and from powerpc, which also came from kexec-tools).


This patch series enables us to
* load the kernel, either Image or vmlinux, with kexec_file_load
system call, and
* optionally verify its signature at load time for trusted boot.

To load the kernel via kexec_file_load system call, a small change
needs to be applied on kexec-tools. See [2]. This enables '-s' option.

As we discussed a long time ago, users may not be allowed to specify
device-tree file of the 2nd kernel explicitly with kexec-tools, therefore
re-using the blob of the first kernel.

Regarding a method of placing the signature into the kernel binary,
* for 'Image', we conform with x86 (or rather Microsoft?) style of
signing since the binary can also be seen as in PE format
(assuming that CONFIG_EFI is enabled),
* for 'vmlinux', we follow powerpc approach[3]: The signature will
be appended just after the binary itself as module signing does.
This implies that we need to enable CONFIG_MODULE_SIG, too.

Powerpc is also going to support extended-file-attribute-based
verification[3], but arm64 doesn't for now partly because we don't
have TPM-based IMA at this moment.

Accordingly, we can use the existing commands, sbsign and sig-file
respectively, to sign the kernel. Please note that it is totally up to
the system what key/certificate is used for signing.

Some concerns(or future works):
* Even if the kernel is configured with CONFIG_RANDOMIZE_BASE, the 2nd
kernel won't be placed at a randomized address. We will have to
add some boot code similar to efi-stub to implement the feature.
* While big-endian kernel can support kernel signing, I'm not sure that
Image can be recognized as in PE format because x86 standard only
defines little-endian-based format.
So I tested big-endian kernel signing only with vmlinux.
* IMA(and file extended attribute)-based kexec


Patch #1 to #7 are all preparatory patches on generic side.
(Patch #1 is not part of mine, but a prerequisite from [4].)
Patch #8 and #9 are purgatory code.
Patch #10 to #12 are common for enabling kexec_file_load.
Patch #13 is for 'Image' support.
Patch #14 is for 'vmlinux' support.


[1] http://git.linaro.org/people/takahiro.akashi/linux-aarch64.git
branch:arm64/kexec_file
[2] http://git.linaro.org/people/takahiro.akashi/kexec-tools.git
branch:arm64/kexec_file
[3] http://lkml.iu.edu//hypermail/linux/kernel/1707.0/03669.html
[4] http://lkml.iu.edu//hypermail/linux/kernel/1707.0/03670.html


AKASHI Takahiro (13):
include: pe.h: remove message[] from mz header definition
resource: add walk_system_ram_res_rev()
kexec_file: factor out vmlinux (elf) parser from powerpc
kexec_file: factor out crashdump elf header function from x86
kexec_file: add kexec_add_segment()
asm-generic: add kexec_file_load system call to unistd.h
arm64: kexec_file: create purgatory
arm64: kexec_file: add sha256 digest check in purgatory
arm64: kexec_file: load initrd, device-tree and purgatory segments
arm64: kexec_file: set up for crash dump adding elf core header
arm64: enable KEXEC_FILE config
arm64: kexec_file: add Image format support
arm64: kexec_file: add vmlinux format support

Thiago Jung Bauermann (1):
MODSIGN: Export module signature definitions

arch/Kconfig | 3 +
arch/arm64/Kconfig | 33 ++
arch/arm64/Makefile | 1 +
arch/arm64/crypto/sha256-core.S_shipped | 2 +
arch/arm64/include/asm/kexec.h | 23 ++
arch/arm64/include/asm/kexec_file.h | 84 +++++
arch/arm64/kernel/Makefile | 5 +-
arch/arm64/kernel/kexec_elf.c | 216 ++++++++++++
arch/arm64/kernel/kexec_image.c | 112 ++++++
arch/arm64/kernel/machine_kexec_file.c | 606 ++++++++++++++++++++++++++++++++
arch/arm64/purgatory/Makefile | 43 +++
arch/arm64/purgatory/entry.S | 41 +++
arch/arm64/purgatory/purgatory.c | 20 ++
arch/arm64/purgatory/sha256-core.S | 1 +
arch/arm64/purgatory/sha256.c | 79 +++++
arch/arm64/purgatory/sha256.h | 1 +
arch/arm64/purgatory/string.c | 32 ++
arch/arm64/purgatory/string.h | 5 +
arch/powerpc/Kconfig | 1 +
arch/powerpc/kernel/kexec_elf_64.c | 464 ------------------------
arch/x86/kernel/crash.c | 324 -----------------
include/linux/elf.h | 62 ++++
include/linux/ioport.h | 3 +
include/linux/kexec.h | 39 ++
include/linux/module.h | 3 -
include/linux/module_signature.h | 47 +++
include/linux/pe.h | 2 +-
include/uapi/asm-generic/unistd.h | 4 +-
init/Kconfig | 6 +-
kernel/Makefile | 3 +-
kernel/crash_core.c | 333 ++++++++++++++++++
kernel/kexec_file.c | 47 +++
kernel/kexec_file_elf.c | 454 ++++++++++++++++++++++++
kernel/module.c | 1 +
kernel/module_signing.c | 74 ++--
kernel/resource.c | 48 +++
36 files changed, 2383 insertions(+), 839 deletions(-)
create mode 100644 arch/arm64/include/asm/kexec_file.h
create mode 100644 arch/arm64/kernel/kexec_elf.c
create mode 100644 arch/arm64/kernel/kexec_image.c
create mode 100644 arch/arm64/kernel/machine_kexec_file.c
create mode 100644 arch/arm64/purgatory/Makefile
create mode 100644 arch/arm64/purgatory/entry.S
create mode 100644 arch/arm64/purgatory/purgatory.c
create mode 100644 arch/arm64/purgatory/sha256-core.S
create mode 100644 arch/arm64/purgatory/sha256.c
create mode 100644 arch/arm64/purgatory/sha256.h
create mode 100644 arch/arm64/purgatory/string.c
create mode 100644 arch/arm64/purgatory/string.h
create mode 100644 include/linux/module_signature.h
create mode 100644 kernel/kexec_file_elf.c

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2.14.1