lkml.org 
[lkml]   [2018]   [Nov]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v16 11/16] arm64: kexec_file: allow for loading Image-format kernel
Date
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>
---
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_RELOC_TEST) += arm64-reloc-test.o
arm64-reloc-test-y := reloc_test_core.o reloc_test_syms.o
arm64-obj-$(CONFIG_CRASH_DUMP) += crash_dump.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
};

--
2.19.0
\
 
 \ /
  Last update: 2018-11-15 06:54    [W:0.155 / U:1.072 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site