Sanitize magiskhide targets

Fix #1785

native/jni/magiskhide/hide_utils.cpp

@@ -57,10 +57,32 @@ static void kill_process(const char *name, bool multi = false) {
 	});
 }
 
+static bool validate(const char *s) {
+	bool dot = false;
+	for (char c; (c = *s); ++s) {
+		if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') ||
+			(c >= '0' && c <= '9') || c == '_') {
+			dot = false;
+			continue;
+		}
+		if (c == '.') {
+			if (dot)  // No consecutive dots
+				return false;
+			dot = true;
+			continue;
+		}
+		return false;
+	}
+	return true;
+}
+
 static int add_list(const char *pkg, const char *proc = "") {
 	if (proc[0] == '\0')
 		proc = pkg;
 
+	if (!validate(pkg) || !validate(proc))
+		return HIDE_INVALID_PKG;
+
 	for (auto &hide : hide_set)
 		if (hide.first == pkg && hide.second == proc)
 			return HIDE_ITEM_EXIST;

native/jni/magiskhide/magiskhide.cpp

@@ -147,8 +147,9 @@ int magiskhide_main(int argc, char *argv[]) {
 	case HIDE_NO_NS:
 		fprintf(stderr, "Your kernel doesn't support mount namespace\n");
 		break;
-
-	/* Errors */
+	case HIDE_INVALID_PKG:
+		fprintf(stderr, "Invalid package / process name\n");
+		break;
 	case ROOT_REQUIRED:
 		fprintf(stderr, "Root is required for this operation\n");
 		break;

native/jni/magiskhide/magiskhide.h

@@ -58,5 +58,6 @@ enum {
 	HIDE_NOT_ENABLED,
 	HIDE_ITEM_EXIST,
 	HIDE_ITEM_NOT_EXIST,
-	HIDE_NO_NS
+	HIDE_NO_NS,
+	HIDE_INVALID_PKG
 };