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

[Lakshmi Ramasubramanian]

On 12/5/20 1:44 PM, Thiago Jung Bauermann wrote:
> Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Prakhar Srivastava <prsriva@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>
>
> Reviewed-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx>
>
> > ---
> >   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?

Yes - will update.

> > + *
> > + * Author: Prakhar Srivastava <prsriva@xxxxxxxxxxxxxxxxxxx>
> > + *
> > + */
> > +#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?
Yes. Also, should be "Copyright (C) 2020 Microsoft Corporation"
Will make these changes.

thanks,
 -lakshmi

> > + *
> > + * Authors:
> > + * Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>
> > + */
> > +
> > +#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;
> > +}