Re: [PATCH v10 8/8] arm64: Add IMA log information in kimage used for kexec

Thiago Jung Bauermann
2020-12-05T21:47:35Z

Lakshmi Ramasubramanian <nramas@linux.microsoft.com> writes:

> Address and size of the buffer containing the IMA measurement log need
> to be passed from the current kernel to the next kernel on kexec.
>
> Any existing "linux,ima-kexec-buffer" property in the device tree
> needs to be removed and its corresponding memory reservation in
> the currently running kernel needs to be freed. The address and
> size of the current kernel's IMA measurement log need to be added
> to the device tree's IMA kexec buffer node and memory for the buffer
> needs to be reserved for the log to be carried over to the next kernel
> on the kexec call.
>
> Add address and size fields to "struct kimage_arch" for ARM64 platform
> to hold the address and size of the IMA measurement log buffer. Remove
> any existing "linux,ima-kexec-buffer" property in the device tree and
> free the corresponding memory reservation in the currently running
> kernel. Add "linux,ima-kexec-buffer" property to the device tree and
> reserve the memory for storing the IMA log that needs to be passed from
> the current kernel to the next one.
>
> Update CONFIG_KEXEC_FILE to select CONFIG_HAVE_IMA_KEXEC to indicate
> that the IMA measurement log information is present in the device tree
> for ARM64.
>
> Co-developed-by: Prakhar Srivastava <prsriva@linux.microsoft.com>
> Signed-off-by: Prakhar Srivastava <prsriva@linux.microsoft.com>
> Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>

Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>

> ---
> arch/arm64/Kconfig | 1 +
> arch/arm64/include/asm/ima.h | 22 ++++++++++++++
> arch/arm64/include/asm/kexec.h | 5 ++++
> arch/arm64/kernel/Makefile | 1 +
> arch/arm64/kernel/ima.c | 41 ++++++++++++++++++++++++++
> arch/arm64/kernel/machine_kexec_file.c | 8 +++++
> 6 files changed, 78 insertions(+)
> create mode 100644 arch/arm64/include/asm/ima.h
> create mode 100644 arch/arm64/kernel/ima.c
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 1515f6f153a0..bcca4a467eda 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1094,6 +1094,7 @@ config KEXEC
> config KEXEC_FILE
> bool "kexec file based system call"
> select KEXEC_CORE
> + select HAVE_IMA_KEXEC
> help
> This is new version of kexec system call. This system call is
> file based and takes file descriptors as system call argument
> diff --git a/arch/arm64/include/asm/ima.h b/arch/arm64/include/asm/ima.h
> new file mode 100644
> index 000000000000..354adc8b444c
> --- /dev/null
> +++ b/arch/arm64/include/asm/ima.h
> @@ -0,0 +1,22 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright (C) 2019 Microsoft Corporation

Shouldn't the year here be 2020?

> + *
> + * Author: Prakhar Srivastava <prsriva@linux.microsoft.com>
> + *
> + */
> +#ifndef _ASM_ARCH_IMA_H
> +#define _ASM_ARCH_IMA_H
> +
> +struct kimage;
> +
> +#ifdef CONFIG_IMA_KEXEC
> +extern int setup_ima_buffer(struct kimage *image, void *dtb, int off);
> +#else
> +static inline int setup_ima_buffer(struct kimage *image, void *dtb, int off)
> +{
> + return 0;
> +}
> +#endif /* CONFIG_IMA_KEXEC */
> +
> +#endif /* _ASM_ARCH_IMA_H */

<snip>

> diff --git a/arch/arm64/kernel/ima.c b/arch/arm64/kernel/ima.c
> new file mode 100644
> index 000000000000..d65bdbe1adf6
> --- /dev/null
> +++ b/arch/arm64/kernel/ima.c
> @@ -0,0 +1,41 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2016 IBM Corporation

Same question: shouldn't the year here be 2020?

> + *
> + * Authors:
> + * Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
> + */
> +
> +#include <linux/kexec.h>
> +#include <linux/of.h>
> +#include <linux/libfdt.h>
> +#include <asm/ima.h>
> +
> +/**
> + * setup_ima_buffer - add IMA buffer information to the fdt
> + *
> + * @image: kexec image being loaded.
> + * @dtb: Flattened device tree for the next kernel.
> + * @off: Offset to the chosen node.
> + *
> + * Return: 0 on success, or negative errno on error.
> + */
> +int setup_ima_buffer(struct kimage *image, void *dtb, int off)
> +{
> + int ret = 0;
> +
> + /* add ima-kexec-buffer */
> + if (image->arch.ima_buffer_size > 0) {
> + ret = fdt_appendprop_addrrange(dtb, 0, off,
> + "linux,ima-kexec-buffer",
> + image->arch.ima_buffer_addr,
> + image->arch.ima_buffer_size);
> + if (ret)
> + return (ret == -FDT_ERR_NOSPACE ? -ENOMEM : -EINVAL);
> +
> + ret = fdt_add_mem_rsv(dtb, image->arch.ima_buffer_addr,
> + image->arch.ima_buffer_size);
> + }
> +
> + return ret;
> +}

--
Thiago Jung Bauermann
IBM Linux Technology Center