Smack: fix the subject/object order in smack_ptrace_traceme()

The order of subject/object is currently reversed in
smack_ptrace_traceme(). It is currently checked if the tracee has a
capability to trace tracer and according to this rule a decision is made
whether the tracer will be allowed to trace tracee.

Signed-off-by: Lukasz Pawelczyk <l.pawelczyk@partner.samsung.com>
Signed-off-by: Rafal Krypa <r.krypa@samsung.com>

security/smack/smack.h

@@ -225,6 +225,7 @@ struct inode_smack *new_inode_smack(char *);
  */
 int smk_access_entry(char *, char *, struct list_head *);
 int smk_access(struct smack_known *, char *, int, struct smk_audit_info *);
+int smk_tskacc(struct task_smack *, char *, u32, struct smk_audit_info *);
 int smk_curacc(char *, u32, struct smk_audit_info *);
 struct smack_known *smack_from_secid(const u32);
 char *smk_parse_smack(const char *string, int len);

security/smack/smack_access.c

@@ -192,20 +192,21 @@ int smk_access(struct smack_known *subject_known, char *object_label,
 }
 
 /**
- * smk_curacc - determine if current has a specific access to an object
+ * smk_tskacc - determine if a task has a specific access to an object
+ * @tsp: a pointer to the subject task
  * @obj_label: a pointer to the object's Smack label
  * @mode: the access requested, in "MAY" format
  * @a : common audit data
  *
- * This function checks the current subject label/object label pair
+ * This function checks the subject task's label/object label pair
  * in the access rule list and returns 0 if the access is permitted,
- * non zero otherwise. It allows that current may have the capability
+ * non zero otherwise. It allows that the task may have the capability
  * to override the rules.
  */
-int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
+int smk_tskacc(struct task_smack *subject, char *obj_label,
+	       u32 mode, struct smk_audit_info *a)
 {
-	struct task_smack *tsp = current_security();
-	struct smack_known *skp = smk_of_task(tsp);
+	struct smack_known *skp = smk_of_task(subject);
 	int may;
 	int rc;
 
@@ -219,7 +220,7 @@ int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
 		 * it can further restrict access.
 		 */
 		may = smk_access_entry(skp->smk_known, obj_label,
-					&tsp->smk_rules);
+					&subject->smk_rules);
 		if (may < 0)
 			goto out_audit;
 		if ((mode & may) == mode)
@@ -241,6 +242,24 @@ int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
 	return rc;
 }
 
+/**
+ * smk_curacc - determine if current has a specific access to an object
+ * @obj_label: a pointer to the object's Smack label
+ * @mode: the access requested, in "MAY" format
+ * @a : common audit data
+ *
+ * This function checks the current subject label/object label pair
+ * in the access rule list and returns 0 if the access is permitted,
+ * non zero otherwise. It allows that current may have the capability
+ * to override the rules.
+ */
+int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
+{
+	struct task_smack *tsp = current_security();
+
+	return smk_tskacc(tsp, obj_label, mode, a);
+}
+
 #ifdef CONFIG_AUDIT
 /**
  * smack_str_from_perm : helper to transalate an int to a

security/smack/smack_lsm.c

@@ -207,11 +207,11 @@ static int smack_ptrace_traceme(struct task_struct *ptp)
 	if (rc != 0)
 		return rc;
 
-	skp = smk_of_task(task_security(ptp));
+	skp = smk_of_task(current_security());
 	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
 	smk_ad_setfield_u_tsk(&ad, ptp);
 
-	rc = smk_curacc(skp->smk_known, MAY_READWRITE, &ad);
+	rc = smk_tskacc(ptp, skp->smk_known, MAY_READWRITE, &ad);
 	return rc;
 }