ima: switch to new template management mechanism

This patch performs the switch to the new template mechanism by modifying
the functions ima_alloc_init_template(), ima_measurements_show() and
ima_ascii_measurements_show(). The old function ima_template_show() was
removed as it is no longer needed. Also, if the template descriptor used
to generate a measurement entry is not 'ima', the whole length of field
data stored for an entry is provided before the data itself through the
binary_runtime_measurement interface.

Changelog:
- unnecessary to use strncmp() (Mimi Zohar)
- create new variable 'field' in ima_alloc_init_template() (Roberto Sassu)
- use GFP_NOFS flag in ima_alloc_init_template() (Roberto Sassu)
- new variable 'num_fields' in ima_store_template() (Roberto Sassu,
  proposed by Mimi Zohar)
- rename ima_calc_buffer_hash/template_hash() to ima_calc_field_array_hash(),
  something more generic (Mimi, requested by Dmitry)
- sparse error fix - Fengguang Wu
- fix lindent warnings
- always include the field length in the template data length
- include the template field length variable size in the template data length
- include both the template field data and field length in the template digest
  calculation. Simplifies verifying the template digest. (Mimi)

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

1 files changed, 27 insertions, 7 deletions

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index 22be23f13b3d..676e0292dfec 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -137,26 +137,46 @@ int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
 }
 
 /*
- * Calculate the hash of a given buffer
+ * Calculate the hash of template data
  */
-static int ima_calc_buffer_hash_tfm(const void *buf, int len,
-				    struct ima_digest_data *hash,
-				    struct crypto_shash *tfm)
+static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
+					 int num_fields,
+					 struct ima_digest_data *hash,
+					 struct crypto_shash *tfm)
 {
 	struct {
 		struct shash_desc shash;
 		char ctx[crypto_shash_descsize(tfm)];
 	} desc;
+	int rc, i;
 
 	desc.shash.tfm = tfm;
 	desc.shash.flags = 0;
 
 	hash->length = crypto_shash_digestsize(tfm);
 
-	return crypto_shash_digest(&desc.shash, buf, len, hash->digest);
+	rc = crypto_shash_init(&desc.shash);
+	if (rc != 0)
+		return rc;
+
+	for (i = 0; i < num_fields; i++) {
+		rc = crypto_shash_update(&desc.shash,
+					 (const u8 *) &field_data[i].len,
+					 sizeof(field_data[i].len));
+		rc = crypto_shash_update(&desc.shash, field_data[i].data,
+					 field_data[i].len);
+		if (rc)
+			break;
+	}
+
+	if (!rc)
+		rc = crypto_shash_final(&desc.shash, hash->digest);
+
+	return rc;
 }
 
-int ima_calc_buffer_hash(const void *buf, int len, struct ima_digest_data *hash)
+int ima_calc_field_array_hash(struct ima_field_data *field_data, int num_fields,
+			      struct ima_digest_data *hash)
 {
 	struct crypto_shash *tfm;
 	int rc;
@@ -165,7 +185,7 @@ int ima_calc_buffer_hash(const void *buf, int len, struct ima_digest_data *hash)
 	if (IS_ERR(tfm))
 		return PTR_ERR(tfm);
 
-	rc = ima_calc_buffer_hash_tfm(buf, len, hash, tfm);
+	rc = ima_calc_field_array_hash_tfm(field_data, num_fields, hash, tfm);
 
 	ima_free_tfm(tfm);