[PATCH v2 09/17] efi_loader: signature: make efi_hash_regions more generic

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

Heinrich,

On Fri, Jul 03, 2020 at 01:08:55PM +0200, Heinrich Schuchardt wrote:
> On 09.06.20 07:09, AKASHI Takahiro wrote:
> > There are a couple of occurrences of hash calculations in which a new
> > efi_hash_regions will be commonly used.
> 
> Please, describe the difference.

the difference of what?

> Do you want to calculate the hash over an interval of regions?

I don't get your point.
What do you mean by "over an interval"?

> >
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> 
> Please, provide a test for efi_hash_regions() in test/lib/.
> 
> > ---
> >  lib/efi_loader/efi_signature.c | 44 +++++++++++++---------------------
> >  1 file changed, 16 insertions(+), 28 deletions(-)
> >
> > diff --git a/lib/efi_loader/efi_signature.c b/lib/efi_loader/efi_signature.c
> > index f22dc151971f..03080bc0b11c 100644
> > --- a/lib/efi_loader/efi_signature.c
> > +++ b/lib/efi_loader/efi_signature.c
> > @@ -30,6 +30,7 @@ const efi_guid_t efi_guid_cert_type_pkcs7 = EFI_CERT_TYPE_PKCS7_GUID;
> >  /**
> >   * efi_hash_regions - calculate a hash value
> >   * @regs:	List of regions
> 
> The argument should be renamed and the description corrected:
> 
> @reg:	first region

No. You don't understand the code.
Here, I refactored the code and simply extracted a common code as
efi_hash_regions.
The first argument is an array of "struct image_region".
(To avoid any confusion, I will change the description to "Array of".)

-Takahiro Akashi

> Best regards
> 
> Heinrich
> 
> > + * @count:	Number of regions
> >   * @hash:	Pointer to a pointer to buffer holding a hash value
> >   * @size:	Size of buffer to be returned
> >   *
> > @@ -37,18 +38,20 @@ const efi_guid_t efi_guid_cert_type_pkcs7 = EFI_CERT_TYPE_PKCS7_GUID;
> >   *
> >   * Return:	true on success, false on error
> >   */
> > -static bool efi_hash_regions(struct efi_image_regions *regs, void **hash,
> > -			     size_t *size)
> > +static bool efi_hash_regions(struct image_region *regs, int count,
> > +			     void **hash, size_t *size)
> >  {
> > -	*size = 0;
> > -	*hash = calloc(1, SHA256_SUM_LEN);
> >  	if (!*hash) {
> > -		EFI_PRINT("Out of memory\n");
> > -		return false;
> > +		*hash = calloc(1, SHA256_SUM_LEN);
> > +		if (!*hash) {
> > +			EFI_PRINT("Out of memory\n");
> > +			return false;
> > +		}
> >  	}
> > -	*size = SHA256_SUM_LEN;
> > +	if (size)
> > +		*size = SHA256_SUM_LEN;
> >
> > -	hash_calculate("sha256", regs->reg, regs->num, *hash);
> > +	hash_calculate("sha256", regs, count, *hash);
> >  #ifdef DEBUG
> >  	EFI_PRINT("hash calculated:\n");
> >  	print_hex_dump("    ", DUMP_PREFIX_OFFSET, 16, 1,
> > @@ -73,26 +76,10 @@ static bool efi_hash_msg_content(struct pkcs7_message *msg, void **hash,
> >  {
> >  	struct image_region regtmp;
> >
> > -	*size = 0;
> > -	*hash = calloc(1, SHA256_SUM_LEN);
> > -	if (!*hash) {
> > -		EFI_PRINT("Out of memory\n");
> > -		free(msg);
> > -		return false;
> > -	}
> > -	*size = SHA256_SUM_LEN;
> > -
> >  	regtmp.data = msg->data;
> >  	regtmp.size = msg->data_len;
> >
> > -	hash_calculate("sha256", &regtmp, 1, *hash);
> > -#ifdef DEBUG
> > -	EFI_PRINT("hash calculated based on contentInfo:\n");
> > -	print_hex_dump("    ", DUMP_PREFIX_OFFSET, 16, 1,
> > -		       *hash, SHA256_SUM_LEN, false);
> > -#endif
> > -
> > -	return true;
> > +	return efi_hash_regions(&regtmp, 1, hash, size);
> >  }
> >
> >  /**
> > @@ -170,9 +157,10 @@ static bool efi_signature_verify(struct efi_image_regions *regs,
> >  			       false);
> >  #endif
> >  		/* against contentInfo first */
> > +		hash = NULL;
> >  		if ((msg->data && efi_hash_msg_content(msg, &hash, &size)) ||
> >  				/* for signed image */
> > -		    efi_hash_regions(regs, &hash, &size)) {
> > +		    efi_hash_regions(regs->reg, regs->num, &hash, &size)) {
> >  				/* for authenticated variable */
> >  			if (ps_info->msgdigest_len != size ||
> >  			    memcmp(hash, ps_info->msgdigest, size)) {
> > @@ -240,7 +228,7 @@ bool efi_signature_verify_with_list(struct efi_image_regions *regs,
> >  		  regs, signed_info, siglist, valid_cert);
> >
> >  	if (!signed_info) {
> > -		void *hash;
> > +		void *hash = NULL;
> >  		size_t size;
> >
> >  		EFI_PRINT("%s: unsigned image\n", __func__);
> > @@ -254,7 +242,7 @@ bool efi_signature_verify_with_list(struct efi_image_regions *regs,
> >  			goto out;
> >  		}
> >
> > -		if (!efi_hash_regions(regs, &hash, &size)) {
> > +		if (!efi_hash_regions(regs->reg, regs->num, &hash, &size)) {
> >  			EFI_PRINT("Digesting unsigned image failed\n");
> >  			goto out;
> >  		}
> >
>