[PATCH v4 9/9] ima: platform-independent hash value

[Mimi Zohar]

From: Andreas Steffen <andreas.steffen@xxxxxxxxxxxxxx>

For remote attestion it is important for the ima measurement values
to be platform-independent. Therefore integer fields to be hashed
must be converted to canonical format.

Changelog:
- Define canonical format as little endian (Mimi)

Signed-off-by: Andreas Steffen <andreas.steffen@xxxxxxxxxxxxxx>
Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
---
 security/integrity/ima/ima_crypto.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index 38f2ed8..802d5d2 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -477,11 +477,13 @@ static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
 		u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 };
 		u8 *data_to_hash = field_data[i].data;
 		u32 datalen = field_data[i].len;
+		u32 datalen_to_hash =
+		    !ima_canonical_fmt ? datalen : cpu_to_le32(datalen);
 
 		if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) {
 			rc = crypto_shash_update(shash,
-						(const u8 *) &field_data[i].len,
-						sizeof(field_data[i].len));
+						(const u8 *) &datalen_to_hash,
+						sizeof(datalen_to_hash));
 			if (rc)
 				break;
 		} else if (strcmp(td->fields[i]->field_id, "n") == 0) {
-- 
2.1.0