ima: extend ima_get_action() to return the policy pcr

Different policy rules may extend different PCRs. This patch retrieves
the specific PCR for the matched rule.  Subsequent patches will include
the rule specific PCR in the measurement list and extend the appropriate
PCR.
Signed-off-by: Eric Richter <erichte@linux.vnet.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

security/integrity/ima/ima.h

@@ -154,7 +154,8 @@ enum ima_hooks {
 };
 
 /* LIM API function definitions */
-int ima_get_action(struct inode *inode, int mask, enum ima_hooks func);
+int ima_get_action(struct inode *inode, int mask,
+		   enum ima_hooks func, int *pcr);
 int ima_must_measure(struct inode *inode, int mask, enum ima_hooks func);
 int ima_collect_measurement(struct integrity_iint_cache *iint,
 			    struct file *file, void *buf, loff_t size,
@@ -174,7 +175,7 @@ const char *ima_d_path(const struct path *path, char **pathbuf);
 
 /* IMA policy related functions */
 int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
-		     int flags);
+		     int flags, int *pcr);
 void ima_init_policy(void);
 void ima_update_policy(void);
 void ima_update_policy_flag(void);

security/integrity/ima/ima_api.c

@@ -157,6 +157,7 @@ void ima_add_violation(struct file *file, const unsigned char *filename,
  * @inode: pointer to inode to measure
  * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE)
  * @func: caller identifier
+ * @pcr: pointer filled in if matched measure policy sets pcr=
  *
  * The policy is defined in terms of keypairs:
  *		subj=, obj=, type=, func=, mask=, fsmagic=
@@ -168,13 +169,13 @@ void ima_add_violation(struct file *file, const unsigned char *filename,
  * Returns IMA_MEASURE, IMA_APPRAISE mask.
  *
  */
-int ima_get_action(struct inode *inode, int mask, enum ima_hooks func)
+int ima_get_action(struct inode *inode, int mask, enum ima_hooks func, int *pcr)
 {
 	int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE;
 
 	flags &= ima_policy_flag;
 
-	return ima_match_policy(inode, func, mask, flags);
+	return ima_match_policy(inode, func, mask, flags, pcr);
 }
 
 /*

security/integrity/ima/ima_appraise.c

@@ -41,7 +41,7 @@ int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func)
 	if (!ima_appraise)
 		return 0;
 
-	return ima_match_policy(inode, func, mask, IMA_APPRAISE);
+	return ima_match_policy(inode, func, mask, IMA_APPRAISE, NULL);
 }
 
 static int ima_fix_xattr(struct dentry *dentry,

security/integrity/ima/ima_main.c

@@ -162,6 +162,7 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
 	char *pathbuf = NULL;
 	const char *pathname = NULL;
 	int rc = -ENOMEM, action, must_appraise;
+	int pcr = CONFIG_IMA_MEASURE_PCR_IDX;
 	struct evm_ima_xattr_data *xattr_value = NULL;
 	int xattr_len = 0;
 	bool violation_check;
@@ -174,7 +175,7 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
 	 * bitmask based on the appraise/audit/measurement policy.
 	 * Included is the appraise submask.
 	 */
-	action = ima_get_action(inode, mask, func);
+	action = ima_get_action(inode, mask, func, &pcr);
 	violation_check = ((func == FILE_CHECK || func == MMAP_CHECK) &&
 			   (ima_policy_flag & IMA_MEASURE));
 	if (!action && !violation_check)

security/integrity/ima/ima_policy.c

@@ -324,6 +324,7 @@ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
  * @inode: pointer to an inode for which the policy decision is being made
  * @func: IMA hook identifier
  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
+ * @pcr: set the pcr to extend
  *
  * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
  * conditions.
@@ -333,7 +334,7 @@ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func)
  * than writes so ima_match_policy() is classical RCU candidate.
  */
 int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
-		     int flags)
+		     int flags, int *pcr)
 {
 	struct ima_rule_entry *entry;
 	int action = 0, actmask = flags | (flags << 1);
@@ -358,6 +359,9 @@ int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
 		else
 			actmask &= ~(entry->action | entry->action >> 1);
 
+		if ((pcr) && (entry->flags & IMA_PCR))
+			*pcr = entry->pcr;
+
 		if (!actmask)
 			break;
 	}