ima: read and use signature hash algorithm

All files on the filesystem, currently, are hashed using the same hash
algorithm.  In preparation for files from different packages being
signed using different hash algorithms, this patch adds support for
reading the signature hash algorithm from the 'security.ima' extended
attribute and calculates the appropriate file data hash based on it.

Changelog:
- fix scripts Lindent and checkpatch msgs - Mimi
- fix md5 support for older version, which occupied 20 bytes in the
  xattr, not the expected 16 bytes.  Fix the comparison to compare
  only the first 16 bytes.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 7708c2120d9..95b5df2c650 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -149,6 +149,8 @@ static int process_measurement(struct file *file, const char *filename,
 	char *pathbuf = NULL;
 	const char *pathname = NULL;
 	int rc = -ENOMEM, action, must_appraise, _func;
+	struct evm_ima_xattr_data *xattr_value = NULL, **xattr_ptr = NULL;
+	int xattr_len = 0;
 
 	if (!ima_initialized || !S_ISREG(inode->i_mode))
 		return 0;
@@ -187,7 +189,10 @@ static int process_measurement(struct file *file, const char *filename,
 		goto out_digsig;
 	}
 
-	rc = ima_collect_measurement(iint, file);
+	if (action & IMA_APPRAISE_SUBMASK)
+		xattr_ptr = &xattr_value;
+
+	rc = ima_collect_measurement(iint, file, xattr_ptr, &xattr_len);
 	if (rc != 0)
 		goto out_digsig;
 
@@ -198,7 +203,8 @@ static int process_measurement(struct file *file, const char *filename,
 	if (action & IMA_MEASURE)
 		ima_store_measurement(iint, file, pathname);
 	if (action & IMA_APPRAISE_SUBMASK)
-		rc = ima_appraise_measurement(_func, iint, file, pathname);
+		rc = ima_appraise_measurement(_func, iint, file, pathname,
+					      xattr_value, xattr_len);
 	if (action & IMA_AUDIT)
 		ima_audit_measurement(iint, pathname);
 	kfree(pathbuf);
@@ -207,6 +213,7 @@ out_digsig:
 		rc = -EACCES;
 out:
 	mutex_unlock(&inode->i_mutex);
+	kfree(xattr_value);
 	if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE))
 		return -EACCES;
 	return 0;