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Commit e201af16 authored by Thiago Jung Bauermann's avatar Thiago Jung Bauermann Committed by Mimi Zohar
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PKCS#7: Introduce pkcs7_get_digest() 



IMA will need to access the digest of the PKCS7 message (as calculated by
the kernel) before the signature is verified, so introduce
pkcs7_get_digest() for that purpose.

Also, modify pkcs7_digest() to detect when the digest was already
calculated so that it doesn't have to do redundant work. Verifying that
sinfo->sig->digest isn't NULL is sufficient because both places which
allocate sinfo->sig (pkcs7_parse_message() and pkcs7_note_signed_info())
use kzalloc() so sig->digest is always initialized to zero.

Signed-off-by: default avatarThiago Jung Bauermann <bauerman@linux.ibm.com>
Reviewed-by: default avatarMimi Zohar <zohar@linux.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: default avatarMimi Zohar <zohar@linux.ibm.com>
parent 2a7bf671

crypto/asymmetric_keys/pkcs7_verify.c

+33 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <linux/err.h>

#include <linux/asn1.h>

#include <crypto/hash.h>

#include <crypto/hash_info.h>

#include <crypto/public_key.h>

#include "pkcs7_parser.h"
@@ -29,6 +30,10 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7, 


	kenter(",%u,%s", sinfo->index, sinfo->sig->hash_algo);



	/* The digest was calculated already. */

	if (sig->digest)

		return 0;



	if (!sinfo->sig->hash_algo)

		return -ENOPKG;
@@ -117,6 +122,34 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7, 
	return ret;

}



int pkcs7_get_digest(struct pkcs7_message *pkcs7, const u8 **buf, u32 *len,

		     enum hash_algo *hash_algo)

{

	struct pkcs7_signed_info *sinfo = pkcs7->signed_infos;

	int i, ret;



	/*

	 * This function doesn't support messages with more than one signature.

	 */

	if (sinfo == NULL || sinfo->next != NULL)

		return -EBADMSG;



	ret = pkcs7_digest(pkcs7, sinfo);

	if (ret)

		return ret;



	*buf = sinfo->sig->digest;

	*len = sinfo->sig->digest_size;



	for (i = 0; i < HASH_ALGO__LAST; i++)

		if (!strcmp(hash_algo_name[i], sinfo->sig->hash_algo)) {

			*hash_algo = i;

			break;

		}



	return 0;

}



/*

 * Find the key (X.509 certificate) to use to verify a PKCS#7 message.  PKCS#7

 * uses the issuer's name and the issuing certificate serial number for

include/crypto/pkcs7.h

+4 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
#define _CRYPTO_PKCS7_H



#include <linux/verification.h>

#include <linux/hash_info.h>

#include <crypto/public_key.h>



struct key;
@@ -40,4 +41,7 @@ extern int pkcs7_verify(struct pkcs7_message *pkcs7, 
extern int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7,

				      const void *data, size_t datalen);



extern int pkcs7_get_digest(struct pkcs7_message *pkcs7, const u8 **buf,

			    u32 *len, enum hash_algo *hash_algo);



#endif /* _CRYPTO_PKCS7_H */