PKCS#7: Make the signature a pointer rather than embedding it

Point to the public_key_signature struct from the pkcs7_signed_info struct
rather than embedding it.  This makes the code consistent with the X.509
signature handling and makes it possible to have a common cleanup function.

We also save a copy of the digest in the signature without sharing the
memory with the crypto layer metadata.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 26 insertions, 25 deletions

diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c
index d8d8d23..1426f03 100644
--- a/crypto/asymmetric_keys/pkcs7_verify.c
+++ b/crypto/asymmetric_keys/pkcs7_verify.c
@@ -25,34 +25,36 @@
 static int pkcs7_digest(struct pkcs7_message *pkcs7,
 			struct pkcs7_signed_info *sinfo)
 {
+	struct public_key_signature *sig = sinfo->sig;
 	struct crypto_shash *tfm;
 	struct shash_desc *desc;
-	size_t digest_size, desc_size;
-	void *digest;
+	size_t desc_size;
 	int ret;
 
-	kenter(",%u,%s", sinfo->index, sinfo->sig.hash_algo);
+	kenter(",%u,%s", sinfo->index, sinfo->sig->hash_algo);
 
-	if (!sinfo->sig.hash_algo)
+	if (!sinfo->sig->hash_algo)
 		return -ENOPKG;
 
 	/* Allocate the hashing algorithm we're going to need and find out how
 	 * big the hash operational data will be.
 	 */
-	tfm = crypto_alloc_shash(sinfo->sig.hash_algo, 0, 0);
+	tfm = crypto_alloc_shash(sinfo->sig->hash_algo, 0, 0);
 	if (IS_ERR(tfm))
 		return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);
 
 	desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
-	sinfo->sig.digest_size = digest_size = crypto_shash_digestsize(tfm);
+	sig->digest_size = crypto_shash_digestsize(tfm);
 
 	ret = -ENOMEM;
-	digest = kzalloc(ALIGN(digest_size, __alignof__(*desc)) + desc_size,
-			 GFP_KERNEL);
-	if (!digest)
+	sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
+	if (!sig->digest)
+		goto error_no_desc;
+
+	desc = kzalloc(desc_size, GFP_KERNEL);
+	if (!desc)
 		goto error_no_desc;
 
-	desc = PTR_ALIGN(digest + digest_size, __alignof__(*desc));
 	desc->tfm   = tfm;
 	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 
@@ -60,10 +62,11 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7,
 	ret = crypto_shash_init(desc);
 	if (ret < 0)
 		goto error;
-	ret = crypto_shash_finup(desc, pkcs7->data, pkcs7->data_len, digest);
+	ret = crypto_shash_finup(desc, pkcs7->data, pkcs7->data_len,
+				 sig->digest);
 	if (ret < 0)
 		goto error;
-	pr_devel("MsgDigest = [%*ph]\n", 8, digest);
+	pr_devel("MsgDigest = [%*ph]\n", 8, sig->digest);
 
 	/* However, if there are authenticated attributes, there must be a
 	 * message digest attribute amongst them which corresponds to the
@@ -78,14 +81,15 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7,
 			goto error;
 		}
 
-		if (sinfo->msgdigest_len != sinfo->sig.digest_size) {
+		if (sinfo->msgdigest_len != sig->digest_size) {
 			pr_debug("Sig %u: Invalid digest size (%u)\n",
 				 sinfo->index, sinfo->msgdigest_len);
 			ret = -EBADMSG;
 			goto error;
 		}
 
-		if (memcmp(digest, sinfo->msgdigest, sinfo->msgdigest_len) != 0) {
+		if (memcmp(sig->digest, sinfo->msgdigest,
+			   sinfo->msgdigest_len) != 0) {
 			pr_debug("Sig %u: Message digest doesn't match\n",
 				 sinfo->index);
 			ret = -EKEYREJECTED;
@@ -97,7 +101,7 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7,
 		 * convert the attributes from a CONT.0 into a SET before we
 		 * hash it.
 		 */
-		memset(digest, 0, sinfo->sig.digest_size);
+		memset(sig->digest, 0, sig->digest_size);
 
 		ret = crypto_shash_init(desc);
 		if (ret < 0)
@@ -107,17 +111,14 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7,
 		if (ret < 0)
 			goto error;
 		ret = crypto_shash_finup(desc, sinfo->authattrs,
-					 sinfo->authattrs_len, digest);
+					 sinfo->authattrs_len, sig->digest);
 		if (ret < 0)
 			goto error;
-		pr_devel("AADigest = [%*ph]\n", 8, digest);
+		pr_devel("AADigest = [%*ph]\n", 8, sig->digest);
 	}
 
-	sinfo->sig.digest = digest;
-	digest = NULL;
-
 error:
-	kfree(digest);
+	kfree(desc);
 error_no_desc:
 	crypto_free_shash(tfm);
 	kleave(" = %d", ret);
@@ -144,12 +145,12 @@ static int pkcs7_find_key(struct pkcs7_message *pkcs7,
 		 * PKCS#7 message - but I can't be 100% sure of that.  It's
 		 * possible this will need element-by-element comparison.
 		 */
-		if (!asymmetric_key_id_same(x509->id, sinfo->signing_cert_id))
+		if (!asymmetric_key_id_same(x509->id, sinfo->sig->auth_ids[0]))
 			continue;
 		pr_devel("Sig %u: Found cert serial match X.509[%u]\n",
 			 sinfo->index, certix);
 
-		if (x509->pub->pkey_algo != sinfo->sig.pkey_algo) {
+		if (x509->pub->pkey_algo != sinfo->sig->pkey_algo) {
 			pr_warn("Sig %u: X.509 algo and PKCS#7 sig algo don't match\n",
 				sinfo->index);
 			continue;
@@ -164,7 +165,7 @@ static int pkcs7_find_key(struct pkcs7_message *pkcs7,
 	 */
 	pr_debug("Sig %u: Issuing X.509 cert not found (#%*phN)\n",
 		 sinfo->index,
-		 sinfo->signing_cert_id->len, sinfo->signing_cert_id->data);
+		 sinfo->sig->auth_ids[0]->len, sinfo->sig->auth_ids[0]->data);
 	return 0;
 }
 
@@ -334,7 +335,7 @@ static int pkcs7_verify_one(struct pkcs7_message *pkcs7,
 	}
 
 	/* Verify the PKCS#7 binary against the key */
-	ret = public_key_verify_signature(sinfo->signer->pub, &sinfo->sig);
+	ret = public_key_verify_signature(sinfo->signer->pub, sinfo->sig);
 	if (ret < 0)
 		return ret;