From: AKASHI Takahiro takahiro.akashi@linaro.org
This patch provides kexec_file_ops for "Image"-format kernel. In this implementation, a binary is always loaded with a fixed offset identified in text_offset field of its header.
Regarding signature verification for trusted boot, this patch doesn't contains CONFIG_KEXEC_VERIFY_SIG support, which is to be added later in this series, but file-attribute-based verification is still a viable option by enabling IMA security subsystem.
You can sign(label) a to-be-kexec'ed kernel image on target file system with: $ evmctl ima_sign --key /path/to/private_key.pem Image
On live system, you must have IMA enforced with, at least, the following security policy: "appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig"
See more details about IMA here: https://sourceforge.net/p/linux-ima/wiki/Home/
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will.deacon@arm.com Reviewed-by: James Morse james.morse@arm.com Signed-off-by: Will Deacon will.deacon@arm.com --- arch/arm64/include/asm/kexec.h | 2 + arch/arm64/kernel/Makefile | 2 +- arch/arm64/kernel/kexec_image.c | 113 +++++++++++++++++++++++++ arch/arm64/kernel/machine_kexec_file.c | 1 + 4 files changed, 117 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/kernel/kexec_image.c
diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h index bbb5f505b0ba..67e4cb75d1fd 100644 --- a/arch/arm64/include/asm/kexec.h +++ b/arch/arm64/include/asm/kexec.h @@ -101,6 +101,8 @@ struct kimage_arch { unsigned long dtb_mem; };
+extern const struct kexec_file_ops kexec_image_ops; + struct kimage;
extern int arch_kimage_file_post_load_cleanup(struct kimage *image); diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 030a39bff117..48868255f09c 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -51,7 +51,7 @@ arm64-obj-$(CONFIG_RANDOMIZE_BASE) += kaslr.o arm64-obj-$(CONFIG_HIBERNATION) += hibernate.o hibernate-asm.o arm64-obj-$(CONFIG_KEXEC_CORE) += machine_kexec.o relocate_kernel.o \ cpu-reset.o -arm64-obj-$(CONFIG_KEXEC_FILE) += machine_kexec_file.o +arm64-obj-$(CONFIG_KEXEC_FILE) += machine_kexec_file.o kexec_image.o arm64-obj-$(CONFIG_ARM64_CPU_PARK) += cpu-park.o arm64-obj-$(CONFIG_ARM64_RELOC_TEST) += arm64-reloc-test.o arm64-reloc-test-y := reloc_test_core.o reloc_test_syms.o diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c new file mode 100644 index 000000000000..9f0d8b5d62d3 --- /dev/null +++ b/arch/arm64/kernel/kexec_image.c @@ -0,0 +1,113 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Kexec image loader + + * Copyright (C) 2018 Linaro Limited + * Author: AKASHI Takahiro takahiro.akashi@linaro.org + */ + +#define pr_fmt(fmt) "kexec_file(Image): " fmt + +#include <linux/err.h> +#include <linux/errno.h> +#include <linux/kernel.h> +#include <linux/kexec.h> +#include <linux/string.h> +#include <asm/byteorder.h> +#include <asm/cpufeature.h> +#include <asm/image.h> +#include <asm/memory.h> + +static int image_probe(const char *kernel_buf, unsigned long kernel_len) +{ + const struct arm64_image_header *h; + + h = (const struct arm64_image_header *)(kernel_buf); + + if (!h || (kernel_len < sizeof(*h)) || + memcmp(&h->magic, ARM64_IMAGE_MAGIC, + sizeof(h->magic))) + return -EINVAL; + + return 0; +} + +static void *image_load(struct kimage *image, + char *kernel, unsigned long kernel_len, + char *initrd, unsigned long initrd_len, + char *cmdline, unsigned long cmdline_len) +{ + struct arm64_image_header *h; + u64 flags, value; + bool be_image, be_kernel; + struct kexec_buf kbuf; + unsigned long text_offset; + struct kexec_segment *kernel_segment; + int ret; + + /* + * We require a kernel with an unambiguous Image header. Per + * Documentation/booting.txt, this is the case when image_size + * is non-zero (practically speaking, since v3.17). + */ + h = (struct arm64_image_header *)kernel; + if (!h->image_size) + return ERR_PTR(-EINVAL); + + /* Check cpu features */ + flags = le64_to_cpu(h->flags); + be_image = arm64_image_flag_field(flags, ARM64_IMAGE_FLAG_BE); + be_kernel = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN); + if ((be_image != be_kernel) && !system_supports_mixed_endian()) + return ERR_PTR(-EINVAL); + + value = arm64_image_flag_field(flags, ARM64_IMAGE_FLAG_PAGE_SIZE); + if (((value == ARM64_IMAGE_FLAG_PAGE_SIZE_4K) && + !system_supports_4kb_granule()) || + ((value == ARM64_IMAGE_FLAG_PAGE_SIZE_64K) && + !system_supports_64kb_granule()) || + ((value == ARM64_IMAGE_FLAG_PAGE_SIZE_16K) && + !system_supports_16kb_granule())) + return ERR_PTR(-EINVAL); + + /* Load the kernel */ + kbuf.image = image; + kbuf.buf_min = 0; + kbuf.buf_max = ULONG_MAX; + kbuf.top_down = false; + + kbuf.buffer = kernel; + kbuf.bufsz = kernel_len; + kbuf.mem = 0; + kbuf.memsz = le64_to_cpu(h->image_size); + text_offset = le64_to_cpu(h->text_offset); + kbuf.buf_align = MIN_KIMG_ALIGN; + + /* Adjust kernel segment with TEXT_OFFSET */ + kbuf.memsz += text_offset; + + ret = kexec_add_buffer(&kbuf); + if (ret) + return ERR_PTR(ret); + + kernel_segment = &image->segment[image->nr_segments - 1]; + kernel_segment->mem += text_offset; + kernel_segment->memsz -= text_offset; + image->start = kernel_segment->mem; + + pr_debug("Loaded kernel at 0x%lx bufsz=0x%lx memsz=0x%lx\n", + kernel_segment->mem, kbuf.bufsz, + kernel_segment->memsz); + + /* Load additional data */ + ret = load_other_segments(image, + kernel_segment->mem, kernel_segment->memsz, + initrd, initrd_len, cmdline); + + return ERR_PTR(ret); +} + +const struct kexec_file_ops kexec_image_ops = { + .probe = image_probe, + .load = image_load, +}; diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c index b433d947d486..7e9d5ed3e238 100644 --- a/arch/arm64/kernel/machine_kexec_file.c +++ b/arch/arm64/kernel/machine_kexec_file.c @@ -26,6 +26,7 @@ #define FDT_PSTR_BOOTARGS "bootargs"
const struct kexec_file_ops * const kexec_file_loaders[] = { + &kexec_image_ops, NULL };