kernel: prevent become manager when failed. close #1328

kernel/core_hook.c

@@ -128,7 +128,8 @@ void escape_to_root(void)
 	// setup capabilities
 	// we need CAP_DAC_READ_SEARCH becuase `/data/adb/ksud` is not accessible for non root process
 	// we add it here but don't add it to cap_inhertiable, it would be dropped automaticly after exec!
-	u64 cap_for_ksud = profile->capabilities.effective | CAP_DAC_READ_SEARCH;
+	u64 cap_for_ksud =
+		profile->capabilities.effective | CAP_DAC_READ_SEARCH;
 	memcpy(&cred->cap_effective, &cap_for_ksud,
 	       sizeof(cred->cap_effective));
 	memcpy(&cred->cap_inheritable, &profile->capabilities.effective,
@@ -243,7 +244,7 @@ int ksu_handle_prctl(int option, unsigned long arg2, unsigned long arg3,
 #ifdef CONFIG_KSU_DEBUG
 			pr_err("become_manager: copy param err\n");
 #endif
-			return 0;
+			goto block;
 		}
 
 		// for user 0, it is /data/data
@@ -261,20 +262,21 @@ int ksu_handle_prctl(int option, unsigned long arg2, unsigned long arg3,
 
 		if (startswith(param, (char *)prefix) != 0) {
 			pr_info("become_manager: invalid param: %s\n", param);
-			return 0;
+			goto block;
 		}
 
 		// stat the param, app must have permission to do this
 		// otherwise it may fake the path!
 		struct path path;
 		if (kern_path(param, LOOKUP_DIRECTORY, &path)) {
 			pr_err("become_manager: kern_path err\n");
-			return 0;
+			goto block;
 		}
-		if (path.dentry->d_inode->i_uid.val != current_uid().val) {
+		uid_t inode_uid = path.dentry->d_inode->i_uid.val;
+		path_put(&path);
+		if (inode_uid != current_uid().val) {
 			pr_err("become_manager: path uid != current uid\n");
-			path_put(&path);
-			return 0;
+			goto block;
 		}
 		char *pkg = param + strlen(prefix);
 		pr_info("become_manager: param pkg: %s\n", pkg);
@@ -284,8 +286,10 @@ int ksu_handle_prctl(int option, unsigned long arg2, unsigned long arg3,
 			if (copy_to_user(result, &reply_ok, sizeof(reply_ok))) {
 				pr_err("become_manager: prctl reply error\n");
 			}
+			return 0;
 		}
-		path_put(&path);
+	block:
+		last_failed_uid = current_uid().val;
 		return 0;
 	}
 
@@ -569,11 +573,13 @@ int ksu_handle_setuid(struct cred *new, const struct cred *old)
 	// when we umount for such process, that is a disaster!
 	bool is_zygote_child = is_zygote(old->security);
 	if (!is_zygote_child) {
-		pr_info("handle umount ignore non zygote child: %d\n", current->pid);
+		pr_info("handle umount ignore non zygote child: %d\n",
+			current->pid);
 		return 0;
 	}
 	// umount the target mnt
-	pr_info("handle umount for uid: %d, pid: %d\n", new_uid.val, current->pid);
+	pr_info("handle umount for uid: %d, pid: %d\n", new_uid.val,
+		current->pid);
 
 	// fixme: use `collect_mounts` and `iterate_mount` to iterate all mountpoint and
 	// filter the mountpoint whose target is `/data/adb`