ima: remove unnecessary call to ima_must_measure

The original ima_must_measure() function based its results on cached
iint information, which required an iint be allocated for all files.
Currently, an iint is allocated only for files in policy.  As a result,
for those files in policy, ima_must_measure() is now called twice: once
to determine if the inode is in the measurement policy and, the second
time, to determine if it needs to be measured/re-measured.

The second call to ima_must_measure() unnecessarily checks to see if
the file is in policy. As we already know the file is in policy, this
patch removes the second unnecessary call to ima_must_measure(), removes
the vestige iint parameter, and just checks the iint directly to determine
if the inode has been measured or needs to be measured/re-measured.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>

security/integrity/ima/ima.h

@@ -110,8 +110,7 @@ struct ima_iint_cache {
 };
 
 /* LIM API function definitions */
-int ima_must_measure(struct ima_iint_cache *iint, struct inode *inode,
-		     int mask, int function);
+int ima_must_measure(struct inode *inode, int mask, int function);
 int ima_collect_measurement(struct ima_iint_cache *iint, struct file *file);
 void ima_store_measurement(struct ima_iint_cache *iint, struct file *file,
 			   const unsigned char *filename);

security/integrity/ima/ima_api.c

@@ -105,20 +105,13 @@ err_out:
  * 	mask: contains the permission mask
  *	fsmagic: hex value
  *
- * Must be called with iint->mutex held.
- *
- * Return 0 to measure. Return 1 if already measured.
- * For matching a DONT_MEASURE policy, no policy, or other
- * error, return an error code.
+ * Return 0 to measure. For matching a DONT_MEASURE policy, no policy,
+ * or other error, return an error code.
 */
-int ima_must_measure(struct ima_iint_cache *iint, struct inode *inode,
-		     int mask, int function)
+int ima_must_measure(struct inode *inode, int mask, int function)
 {
 	int must_measure;
 
-	if (iint && iint->flags & IMA_MEASURED)
-		return 1;
-
 	must_measure = ima_match_policy(inode, function, mask);
 	return must_measure ? 0 : -EACCES;
 }

security/integrity/ima/ima_main.c

@@ -65,7 +65,7 @@ static void ima_rdwr_violation_check(struct file *file)
 		goto out;
 	}
 
-	rc = ima_must_measure(NULL, inode, MAY_READ, FILE_CHECK);
+	rc = ima_must_measure(inode, MAY_READ, FILE_CHECK);
 	if (rc < 0)
 		goto out;
 
@@ -127,7 +127,7 @@ static int process_measurement(struct file *file, const unsigned char *filename,
 	if (!ima_initialized || !S_ISREG(inode->i_mode))
 		return 0;
 
-	rc = ima_must_measure(NULL, inode, mask, function);
+	rc = ima_must_measure(inode, mask, function);
 	if (rc != 0)
 		return rc;
 retry:
@@ -141,7 +141,7 @@ retry:
 
 	mutex_lock(&iint->mutex);
 
-	rc = ima_must_measure(iint, inode, mask, function);
+	rc = iint->flags & IMA_MEASURED ? 1 : 0;
 	if (rc != 0)
 		goto out;