Hi Prahkar,
On Fri, 2019-09-13 at 15:50 -0700, Prakhar Srivastava wrote:
> During kexec_file_load, carrying forward the ima measurement log allows
> a verifying party to get the entire runtime event log since the last
> full reboot since that is when PCRs were last reset.
>
> Signed-off-by: Prakhar Srivastava <prsriva@xxxxxxxxxxxxxxxxxxx>
Missing is the Changelog between versions. (v1 has now been posted 3
times.)
There's a number of trailing whitespaces, blanks before tabs, and
other warnings. Please use scripts/checkpatch.pl before posting
patches.
> ---
> arch/arm64/Kconfig | 7 +
> arch/arm64/include/asm/ima.h | 29 ++++
> arch/arm64/include/asm/kexec.h | 5 +
> arch/arm64/kernel/Makefile | 3 +-
> arch/arm64/kernel/ima_kexec.c | 213 +++++++++++++++++++++++++
> arch/arm64/kernel/machine_kexec_file.c | 6 +
> 6 files changed, 262 insertions(+), 1 deletion(-)
> create mode 100644 arch/arm64/include/asm/ima.h
> create mode 100644 arch/arm64/kernel/ima_kexec.c
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 3adcec05b1f6..f39b12dbf9e8 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -976,6 +976,13 @@ config KEXEC_VERIFY_SIG
> verification for the corresponding kernel image type being
> loaded in order for this to work.
>
> +config HAVE_IMA_KEXEC
> + bool "Carry over IMA measurement log during kexec_file_load() syscall"
> + depends on KEXEC_FILE
> + help
> + Select this option to carry over IMA measurement log during
> + kexec_file_load.
> +
> config KEXEC_IMAGE_VERIFY_SIG
> bool "Enable Image signature verification support"
> default y
> diff --git a/arch/arm64/include/asm/ima.h b/arch/arm64/include/asm/ima.h
> new file mode 100644
> index 000000000000..e23cee84729f
> --- /dev/null
> +++ b/arch/arm64/include/asm/ima.h
> @@ -0,0 +1,29 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_ARM64_IMA_H
> +#define _ASM_ARM64_IMA_H
> +
> +struct kimage;
> +
> +int ima_get_kexec_buffer(void **addr, size_t *size);
> +int ima_free_kexec_buffer(void);
> +
> +#ifdef CONFIG_IMA
> +void remove_ima_buffer(void *fdt, int chosen_node);
> +#else
> +static inline void remove_ima_buffer(void *fdt, int chosen_node) {}
> +#endif
> +
> +#ifdef CONFIG_IMA_KEXEC
> +int arch_ima_add_kexec_buffer(struct kimage *image, unsigned long load_addr,
> + size_t size);
> +
> +int setup_ima_buffer(const struct kimage *image, void *fdt, int chosen_node);
> +#else
> +static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
> + int chosen_node)
> +{
> + remove_ima_buffer(fdt, chosen_node);
> + return 0;
> +}
> +#endif /* CONFIG_IMA_KEXEC */
> +#endif /* _ASM_ARM64_IMA_H */
> diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
> index 12a561a54128..e8d2412066e7 100644
> --- a/arch/arm64/include/asm/kexec.h
> +++ b/arch/arm64/include/asm/kexec.h
> @@ -96,6 +96,11 @@ static inline void crash_post_resume(void) {}
> struct kimage_arch {
> void *dtb;
> unsigned long dtb_mem;
> +
> +#ifdef CONFIG_IMA_KEXEC
> + phys_addr_t ima_buffer_addr;
> + size_t ima_buffer_size;
> +#endif
> };
>
> extern const struct kexec_file_ops kexec_image_ops;
> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
> index 478491f07b4f..580238f2e9a7 100644
> --- a/arch/arm64/kernel/Makefile
> +++ b/arch/arm64/kernel/Makefile
> @@ -55,7 +55,8 @@ obj-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
> obj-$(CONFIG_HIBERNATION) += hibernate.o hibernate-asm.o
> obj-$(CONFIG_KEXEC_CORE) += machine_kexec.o relocate_kernel.o \
> cpu-reset.o
> -obj-$(CONFIG_KEXEC_FILE) += machine_kexec_file.o kexec_image.o
> +obj-$(CONFIG_KEXEC_FILE) += machine_kexec_file.o kexec_image.o \
> + ima_kexec.o
The kernel may be built with/without IMA enabled or without IMA_KEXEC
support. Here you're requiring both IMA and IMA_KEXEC to be
configured. Please refer to the powerpc example.
> obj-$(CONFIG_ARM64_RELOC_TEST) += arm64-reloc-test.o
> arm64-reloc-test-y := reloc_test_core.o reloc_test_syms.o
> obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
> diff --git a/arch/arm64/kernel/ima_kexec.c b/arch/arm64/kernel/ima_kexec.c
> new file mode 100644
> index 000000000000..b14326d541f3
> --- /dev/null
> +++ b/arch/arm64/kernel/ima_kexec.c
> @@ -0,0 +1,213 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2019 Microsoft Corporation.
> + *
> + * Authors:
> + * Prakhar Srivastava <prsriva@xxxxxxxxxxxxxxxxxxx>
> + */
> +
> +#include <linux/slab.h>
> +#include <linux/kexec.h>
> +#include <linux/of.h>
> +#include <linux/memblock.h>
> +#include <linux/libfdt.h>
> +
> +
Extraneous blank line.
> +/**
> + * delete_fdt_mem_rsv - delete memory reservation with given address and size
> + * @fdt - pointer to the fdt.
> + * @start - start address of the memory.
> + * @size - number of cells to be deletd.
> + *
> + * Return: 0 on success, or negative errno on error.
> + */
> +int delete_fdt_mem_rsv(void *fdt, unsigned long start, unsigned long size)
> +{
> + int i, ret, num_rsvs = fdt_num_mem_rsv(fdt);
> +
> + for (i = 0; i < num_rsvs; i++) {
> + uint64_t rsv_start, rsv_size;
> +
> + ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
> + if (ret) {
> + pr_err("Malformed device tree\n");
> + return -EINVAL;
> + }
> +
> + if (rsv_start == start && rsv_size == size) {
> + ret = fdt_del_mem_rsv(fdt, i);
> + if (ret) {
> + pr_err("Error deleting device tree reservation\n");
> + return -EINVAL;
> + }
> +
> + return 0;
> + }
> + }
> +
> + return -ENOENT;
> +}
> +
> +/**
> + * remove_ima_buffer - remove the IMA buffer property and reservation
> + * @fdt - pointer the fdt.
> + * @chosen_node - node under which property can be found.
> + *
> + * The IMA measurement buffer is either read by now and freeed or a kexec call
> + * needs to replace the ima measurement buffer, clear the property and memory
> + * reservation.
> + */
> +void remove_ima_buffer(void *fdt, int chosen_node)
> +{
> + int ret, len;
> + const void *prop;
> + uint64_t tmp_start, tmp_end;
> +
> + prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);
> + if (prop) {
> + tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop));
> +
> + prop = fdt_getprop(fdt, chosen_node,
> + "linux,ima-kexec-buffer-end", &len);
> + if (!prop)
> + return;
> +
> + tmp_end = fdt64_to_cpu(*((const fdt64_t *) prop));
> +
> + ret = delete_fdt_mem_rsv(fdt, tmp_start, tmp_end - tmp_start);
> +
> + if (ret == 0)
> + pr_debug("Removed old IMA buffer reservation.\n");
> + else if (ret != -ENOENT)
> + return;
> +
> + fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
> + fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer-end");
> + }
> +}
> +
> +/**
> + * ima_get_kexec_buffer - get IMA buffer from the previous kernel
> + * @addr: On successful return, set to point to the buffer contents.
> + * @size: On successful return, set to the buffer size.
> + *
> + * Return: 0 on success, negative errno on error.
> + */
> +int ima_get_kexec_buffer(void **addr, size_t *size)
> +{
> + int len;
> + const void *prop;
> + uint64_t tmp_start, tmp_end;
> +
> + prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);
> + if (!prop)
> + return -ENOENT;
> +
> + tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop));
> +
> + prop = of_get_property(of_chosen, "linux,ima-kexec-buffer-end", &len);
> + if (!prop)
> + return -ENOENT;
> +
> + tmp_end = fdt64_to_cpu(*((const fdt64_t *) prop));
> +
> + *addr = __va(tmp_start);
> + *size = tmp_end - tmp_start;
> +
> + return 0;
> +}
> +
> +/**
> + * ima_free_kexec_buffer - free memory used by the IMA buffer
> + *
> + * Return: 0 on success, negative errno on error.
> + */
> +int ima_free_kexec_buffer(void)
> +{
> + int ret;
> + void *propStart, *propEnd;
Is there a reason for using mixed case variables? Why does the
variable need to be prefixed with "prop"? Wouldn't ima_start/_stop,
buffer_start/_stop, or even buf_start/_stop be fine?
> + uint64_t tmp_start, tmp_end;
> +
> + propStart = of_find_property(of_chosen, "linux,ima-kexec-buffer",
> + NULL);
> + if (propStart) {
> + tmp_start = fdt64_to_cpu(*((const fdt64_t *) propStart));
> + ret = of_remove_property(of_chosen, propStart);
> + if (!ret) {
> + return ret;
> + }
> +
> + propEnd = of_find_property(of_chosen,
> + "linux,ima-kexec-buffer-end", NULL);
> + if (!propEnd) {
> + return -EINVAL;
> + }
> +
> + tmp_end = fdt64_to_cpu(*((const fdt64_t *) propEnd));
> +
> + ret = of_remove_property(of_chosen, propEnd);
> + if (!ret) {
> + return ret;
> + }
There seems to be quite a bit of code duplication in this function and
in ima_get_kexec_buffer(). It could probably be cleaned up with some
refactoring.
Mimi
> +
> + return memblock_free(tmp_start, tmp_end - tmp_start);
> + }
> + return 0;
> +}
> +
> +#ifdef CONFIG_IMA_KEXEC
> +/**
> + * arch_ima_add_kexec_buffer - do arch-specific steps to add the IMA
> + * measurement log.
> + * @image: - pointer to the kimage, to store the address and size of the
> + * IMA measurement log.
> + * @load_addr: - the address where the IMA measurement log is stored.
> + * @size - size of the IMA measurement log.
> + *
> + * Return: 0 on success, negative errno on error.
> + */
> +int arch_ima_add_kexec_buffer(struct kimage *image, unsigned long load_addr,
> + size_t size)
> +{
> + image->arch.ima_buffer_addr = load_addr;
> + image->arch.ima_buffer_size = size;
> + return 0;
> +}
> +
> +/**
> + * setup_ima_buffer - update the fdt to contain the ima mesasurement log
> + * @image: - pointer to the kimage, containing the address and size of
> + * the IMA measurement log.
> + * @fdt: - pointer to the fdt.
> + * @chosen_node: - node under which property is to be defined.
> + *
> + * Return: 0 on success, negative errno on error.
> + */
> +int setup_ima_buffer(const struct kimage *image, void *fdt, int chosen_node)
> +{
> + int ret;
> +
> + remove_ima_buffer(fdt, chosen_node);
> +
> + if (!image->arch.ima_buffer_size)
> + return 0;
> +
> + ret = fdt_setprop_u64(fdt, chosen_node, "linux,ima-kexec-buffer",
> + image->arch.ima_buffer_addr);
> + if (ret < 0)
> + return ret;
> +
> + ret = fdt_setprop_u64(fdt, chosen_node, "linux,ima-kexec-buffer-end",
> + image->arch.ima_buffer_addr +
> + image->arch.ima_buffer_size);
> + if (ret < 0)
> + return ret;
> +
> + ret = fdt_add_mem_rsv(fdt, image->arch.ima_buffer_addr,
> + image->arch.ima_buffer_size);
> + if (ret < 0)
> + return ret;
> +
> + return 0;
> +}
> +#endif /* CONFIG_IMA_KEXEC */
> diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
> index 58871333737a..de5452539c67 100644
> --- a/arch/arm64/kernel/machine_kexec_file.c
> +++ b/arch/arm64/kernel/machine_kexec_file.c
> @@ -21,6 +21,7 @@
> #include <linux/types.h>
> #include <linux/vmalloc.h>
> #include <asm/byteorder.h>
> +#include <asm/ima.h>
>
> /* relevant device tree properties */
> #define FDT_PROP_INITRD_START "linux,initrd-start"
> @@ -85,6 +86,11 @@ static int setup_dtb(struct kimage *image,
> goto out;
> }
>
> + /* add ima measuremnet log buffer */
> + ret = setup_ima_buffer(image, dtb, off);
> + if (ret)
> + goto out;
> +
> /* add kaslr-seed */
> ret = fdt_delprop(dtb, off, FDT_PROP_KASLR_SEED);
> if (ret == -FDT_ERR_NOTFOUND)
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