Re: [PATCH v12 2/4] powerpc: Move arch independent ima kexec functions to drivers/of/kexec.c

[Lakshmi Ramasubramanian <nramas@linux.microsoft.com>]

On 12/17/20 12:05 PM, Rob Herring wrote:
> On Thu, Dec 17, 2020 at 09:37:06AM -0800, Lakshmi Ramasubramanian wrote:
>> The functions defined in "arch/powerpc/kexec/ima.c" handle setting up
>> and freeing the resources required to carry over the IMA measurement
>> list from the current kernel to the next kernel across kexec system call.
>> These functions do not have architecture specific code, but are
>> currently limited to powerpc.
>>
>> Move setup_ima_buffer() call into of_kexec_setup_new_fdt().
>>
>> Move architecture independent functions from "arch/powerpc/kexec/ima.c"
>> to "drivers/of/kexec.c". Delete "arch/powerpc/kexec/ima.c" and
>> "arch/powerpc/include/asm/ima.h". Remove references to the deleted files
>> in powerpc and in ima.
>>
>> delete_fdt_mem_rsv() defined in "arch/powerpc/kexec/file_load.c"
>> is not used anymore. Remove this function.
> 
> I think this patch should come first and then patch 1. Move then rework
> the code.

Sure - will reorder the patches.

> 
>>
>> Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
>> ---
>>   arch/powerpc/include/asm/ima.h     |  30 -----
>>   arch/powerpc/include/asm/kexec.h   |   1 -
>>   arch/powerpc/kexec/Makefile        |   7 -
>>   arch/powerpc/kexec/file_load.c     |  39 ------
>>   arch/powerpc/kexec/ima.c           | 182 --------------------------
>>   drivers/of/kexec.c                 | 198 +++++++++++++++++++++++++++++
>>   include/linux/of.h                 |  17 +++
>>   security/integrity/ima/ima.h       |   4 -
>>   security/integrity/ima/ima_kexec.c |   2 +
>>   9 files changed, 217 insertions(+), 263 deletions(-)
>>   delete mode 100644 arch/powerpc/include/asm/ima.h
>>   delete mode 100644 arch/powerpc/kexec/ima.c
>>

>> diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
>> index 66787be081fe..a6ab35f16dd2 100644
>> --- a/drivers/of/kexec.c
>> +++ b/drivers/of/kexec.c
>> @@ -10,10 +10,12 @@
>>    */
>>   
>>   #include <linux/kernel.h>
>> +#include <linux/slab.h>
>>   #include <linux/kexec.h>
>>   #include <linux/libfdt.h>
>>   #include <linux/of.h>
>>   #include <linux/of_fdt.h>
>> +#include <linux/memblock.h>
>>   #include <linux/random.h>
>>   #include <linux/types.h>
>>   
>> @@ -59,6 +61,141 @@ static int fdt_find_and_del_mem_rsv(void *fdt, unsigned long start, unsigned lon
>>   	return -ENOENT;
>>   }
>>   
>> +/**
>> + * get_addr_size_cells - Get address and size of root node
>> + *
>> + * @addr_cells: Return address of the root node
>> + * @size_cells: Return size of the root node
>> + *
>> + * Return: 0 on success, or negative errno on error.
>> + */
>> +static int get_addr_size_cells(int *addr_cells, int *size_cells)
>> +{
>> +	struct device_node *root;
>> +
>> +	root = of_find_node_by_path("/");
>> +	if (!root)
>> +		return -EINVAL;
>> +
>> +	*addr_cells = of_n_addr_cells(root);
>> +	*size_cells = of_n_size_cells(root);
>> +
>> +	of_node_put(root);
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * do_get_kexec_buffer - Get address and size of device tree property
>> + *
>> + * @prop: Device tree property
>> + * @len: Size of @prop
>> + * @addr: Return address of the node
>> + * @size: Return size of the node
>> + *
>> + * Return: 0 on success, or negative errno on error.
>> + */
>> +static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
>> +			       size_t *size)
>> +{
>> +	int ret, addr_cells, size_cells;
>> +
>> +	ret = get_addr_size_cells(&addr_cells, &size_cells);
>> +	if (ret)
>> +		return ret;
>> +
>> +	if (len < 4 * (addr_cells + size_cells))
>> +		return -ENOENT;
>> +
>> +	*addr = of_read_number(prop, addr_cells);
>> +	*size = of_read_number(prop + 4 * addr_cells, size_cells);
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * 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 ret, len;
>> +	unsigned long tmp_addr;
>> +	size_t tmp_size;
>> +	const void *prop;
>> +
>> +	prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);
>> +	if (!prop)
>> +		return -ENOENT;
>> +
>> +	ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);
>> +	if (ret)
>> +		return ret;
>> +
>> +	*addr = __va(tmp_addr);
>> +	*size = tmp_size;
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * ima_free_kexec_buffer - free memory used by the IMA buffer
>> + */
>> +int ima_free_kexec_buffer(void)
>> +{
>> +	int ret;
>> +	unsigned long addr;
>> +	size_t size;
>> +	struct property *prop;
>> +
>> +	prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL);
>> +	if (!prop)
>> +		return -ENOENT;
>> +
>> +	ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = of_remove_property(of_chosen, prop);
>> +	if (ret)
>> +		return ret;
>> +
>> +	return memblock_free(addr, size);
>> +}
>> +
>> +/**
>> + * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
>> + *
>> + * @fdt: Flattened Device Tree to update
>> + * @chosen_node: Offset to the chosen node in the device tree
>> + *
>> + * The IMA measurement buffer is of no use to a subsequent kernel, so we always
>> + * remove it from the device tree.
>> + */
>> +void remove_ima_buffer(void *fdt, int chosen_node)
> 
> static

Will update.

> 
>> +{
>> +	int ret, len;
>> +	unsigned long addr;
>> +	size_t size;
>> +	const void *prop;
>> +
>> +	prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);
>> +	if (!prop)
>> +		return;
>> +
>> +	ret = do_get_kexec_buffer(prop, len, &addr, &size);
>> +	fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
>> +	if (ret)
>> +		return;
>> +
>> +	ret = fdt_find_and_del_mem_rsv(fdt, addr, size);
>> +	if (!ret)
>> +		pr_debug("Removed old IMA buffer reservation.\n");
>> +}
> 
> All the above needs to be in an '#ifdef CONFIG_IMA_KEXEC'.

remove_ima_buffer() needs to be defined when CONFIG_HAVE_IMA_KEXEC is 
enabled. CONFIG_HAVE_IMA_KEXEC can be enabled even if CONFIG_IMA_KEXEC 
is not.

I'll move remove_ima_buffer() under "#ifdef CONFIG_HAVE_IMA_KEXEC" in 
this file.

> 
>> +
>>   /*
>>    * of_kexec_setup_new_fdt - modify /chosen and memory reservation for the next kernel
>>    *
>> @@ -219,6 +356,10 @@ int of_kexec_setup_new_fdt(const struct kimage *image, void *fdt,
>>   	}
>>   
>>   	ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
>> +	if (ret)
>> +		goto out;
>> +
>> +	ret = setup_ima_buffer(image, fdt, fdt_path_offset(fdt, "/chosen"));
>>   
>>   out:
>>   	if (ret)
>> @@ -226,3 +367,60 @@ int of_kexec_setup_new_fdt(const struct kimage *image, void *fdt,
>>   
>>   	return 0;
>>   }
>> +
>> +#ifdef CONFIG_IMA_KEXEC
>> +/**
>> + * arch_ima_add_kexec_buffer - do arch-specific steps to add the IMA buffer
>> + *
>> + * @image: kimage struct to set IMA buffer data
>> + * @load_addr: Starting address where IMA buffer is loaded at
>> + * @size: Number of bytes in the IMA buffer
>> + *
>> + * Architectures should use this function to pass on the IMA buffer
>> + * information to the next kernel.
>> + *
>> + * Return: 0 on success, negative errno on error.
>> + */
>> +int arch_ima_add_kexec_buffer(struct kimage *image, unsigned long load_addr,
>> +			      size_t size)
> 
> This should be a static inline in asm/kexec.h.

arch_ima_add_kexec_buffer() is identical for powerpc and arm64.
Would it be better to "static inline" this function in "of.h" instead of 
duplicating it in "asm/kexec.h" for powerpc and arm64?

> 
>> +{
>> +	image->arch.ima_buffer_addr = load_addr;
>> +	image->arch.ima_buffer_size = size;
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * setup_ima_buffer - add IMA buffer information to the fdt
>> + * @image:		kexec image being loaded.
>> + * @fdt:		Flattened device tree for the next kernel.
>> + * @chosen_node:	Offset to the chosen node.
>> + *
>> + * Return: 0 on success, or negative errno on error.
>> + */
>> +int setup_ima_buffer(const struct kimage *image, void *fdt, int chosen_node)
> 
> static
Will update.

> 
>> +{
>> +	int ret;
>> +
>> +	remove_ima_buffer(fdt, chosen_node);
>> +	if (!image->arch.ima_buffer_size)
>> +		return 0;
>> +
>> +	ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
>> +				       "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(fdt, image->arch.ima_buffer_addr,
>> +			      image->arch.ima_buffer_size);
>> +	if (ret)
>> +		return -EINVAL;
>> +
>> +	pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n",
>> +		 image->arch.ima_buffer_addr, image->arch.ima_buffer_size);
>> +
>> +	return 0;
>> +}
>> +#endif /* CONFIG_IMA_KEXEC */
>> diff --git a/include/linux/of.h b/include/linux/of.h
>> index 3375f5295875..7477f2266d8f 100644
>> --- a/include/linux/of.h
>> +++ b/include/linux/of.h
>> @@ -562,6 +562,23 @@ struct kimage;
>>   int of_kexec_setup_new_fdt(const struct kimage *image, void *fdt,
>>   			   unsigned long initrd_load_addr, unsigned long initrd_len,
>>   			   const char *cmdline);
>> +int ima_get_kexec_buffer(void **addr, size_t *size);
>> +int ima_free_kexec_buffer(void);
>> +void remove_ima_buffer(void *fdt, int chosen_node);
>> +
>> +#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);
> 
> This doesn't need to be public.

Will update.

thanks,
  -lakshmi

> 
>> +#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 */
>>   
>>   #else /* CONFIG_OF */
>>   
>> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
>> index 6ebefec616e4..7c3947ad3773 100644
>> --- a/security/integrity/ima/ima.h
>> +++ b/security/integrity/ima/ima.h
>> @@ -24,10 +24,6 @@
>>   
>>   #include "../integrity.h"
>>   
>> -#ifdef CONFIG_HAVE_IMA_KEXEC
>> -#include <asm/ima.h>
>> -#endif
>> -
>>   enum ima_show_type { IMA_SHOW_BINARY, IMA_SHOW_BINARY_NO_FIELD_LEN,
>>   		     IMA_SHOW_BINARY_OLD_STRING_FMT, IMA_SHOW_ASCII };
>>   enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8, TPM_PCR10 = 10 };
>> diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
>> index 121de3e04af2..3d6a8820e2a5 100644
>> --- a/security/integrity/ima/ima_kexec.c
>> +++ b/security/integrity/ima/ima_kexec.c
>> @@ -9,7 +9,9 @@
>>   
>>   #include <linux/seq_file.h>
>>   #include <linux/vmalloc.h>
>> +#include <linux/of.h>
>>   #include <linux/kexec.h>
>> +#include <linux/ima.h>
>>   #include "ima.h"
>>   
>>   #ifdef CONFIG_IMA_KEXEC
>> -- 
>> 2.29.2
>>