Re: [PATCH v2 10/14] platform/x86/intel/ifs: Add metadata validation

[Borislav Petkov <bp@alien8.de>]

On Mon, Nov 07, 2022 at 02:53:19PM -0800, Jithu Joseph wrote:
> diff --git a/drivers/platform/x86/intel/ifs/load.c b/drivers/platform/x86/intel/ifs/load.c
> index 7c0d8602817b..f361fd42a320 100644
> --- a/drivers/platform/x86/intel/ifs/load.c
> +++ b/drivers/platform/x86/intel/ifs/load.c
> @@ -8,7 +8,23 @@
>  
>  #include "ifs.h"
>  
> +struct meta_data {
> +	unsigned int meta_type;		// metadata type
> +	unsigned int meta_size;		// size of this entire struct including hdrs.
> +	unsigned int test_type;		// IFS test type
> +	unsigned int fusa_info;		// Fusa info
> +	unsigned int total_images;	// Total number of images
> +	unsigned int current_image;	// Current Image #
> +	unsigned int total_chunks;	// Total number of chunks in this image
> +	unsigned int starting_chunk;	// Starting chunk number in this image
> +	unsigned int size_per_chunk;	// size of each chunk
> +	unsigned int chunks_per_stride;	// number of chunks in a stride
> +	unsigned int reserved[54];	// Align to 256 bytes for chunk alignment.

That looks weird.

__packed and __aligned doesn't work?

>  #define IFS_HEADER_SIZE	(sizeof(struct microcode_header_intel))
> +#define META_TYPE_IFS	1
> +#define IFS_CHUNK_ALIGNMENT	256
>  static  struct microcode_header_intel *ifs_header_ptr;	/* pointer to the ifs image header */
>  static u64 ifs_hash_ptr;			/* Address of ifs metadata (hash) */
>  static u64 ifs_test_image_ptr;			/* 256B aligned address of test pattern */
> @@ -129,6 +145,40 @@ static void copy_hashes_authenticate_chunks(struct work_struct *work)
>  	complete(&ifs_done);
>  }
>  
> +static int validate_ifs_metadata(struct device *dev)
> +{
> +	struct ifs_data *ifsd = ifs_get_data(dev);
> +	struct meta_data *ifs_meta;
> +	char test_file[64];
> +	int ret = -EINVAL;
> +
> +	snprintf(test_file, sizeof(test_file), "%02x-%02x-%02x-%02x.scan",
> +		 boot_cpu_data.x86, boot_cpu_data.x86_model,
> +		 boot_cpu_data.x86_stepping, ifsd->cur_batch);
> +
> +	ifs_meta = (struct meta_data *)ifs_find_meta_data(ifs_header_ptr, META_TYPE_IFS);
> +	if (!ifs_meta) {
> +		dev_err(dev, "IFS Metadata missing in file %s\n", test_file);
> +		return ret;
> +	}
> +
> +	ifs_test_image_ptr = (u64)ifs_meta + sizeof(struct meta_data);
> +
> +	/* Scan chunk start must be 256 byte aligned */
> +	if (!IS_ALIGNED(ifs_test_image_ptr, IFS_CHUNK_ALIGNMENT)) {
> +		dev_err(dev, "Scan pattern offset is not 256 byte aligned in %s\n", test_file);

	" ... is not aligned on %d bytes...\n", test_file, IFS_CHUNK_ALIGNMENT);

> +		return ret;
> +	}
> +
> +	if (ifs_meta->current_image != ifsd->cur_batch) {
> +		dev_warn(dev, "Mismatch between filename %s and batch metadata 0x%02x\n",
> +			 test_file, ifs_meta->current_image);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
>  /*
>   * IFS requires scan chunks authenticated per each socket in the platform.
>   * Once the test chunk is authenticated, it is automatically copied to secured memory
> @@ -145,6 +195,9 @@ static int scan_chunks_sanity_check(struct device *dev)
>  	if (!package_authenticated)
>  		return ret;
>  
> +	ret = validate_ifs_metadata(dev);
> +	if (ret)
> +		return ret;

Right, if you return here because validate_ifs_metadata() failed for
whatever reason, you leak package_authenticated. That's why, as I said
earlier, you should just use a stack variable where you simply set a
bit. A bitmask or so.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette