Added prop hiding

.gitmodules

@@ -4,3 +4,6 @@
 [submodule "module/jni/libcxx"]
 	path = module/jni/libcxx
 	url = https://github.com/topjohnwu/libcxx.git
+[submodule "module/jni/system_properties"]
+	path = module/jni/system_properties
+	url = https://github.com/topjohnwu/system_properties

module/jni/Android.mk

@@ -4,8 +4,9 @@ include $(CLEAR_VARS)
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/include $(LOCAL_PATH)/elfio
 LOCAL_MODULE := zygisk
 LOCAL_SRC_FILES := utils.cpp map_parser.cpp mountinfo_parser.cpp modules.cpp main.cpp
-LOCAL_STATIC_LIBRARIES := libcxx
+LOCAL_STATIC_LIBRARIES := libcxx libsystemproperties
 LOCAL_LDLIBS := -llog
 include $(BUILD_SHARED_LIBRARY)
 
 include jni/libcxx/Android.mk
+include jni/system_properties/Android.mk

module/jni/include/modules.hpp

@@ -3,3 +3,4 @@
 void doUnmount();
 void doRemount();
 void doHideZygisk();
+void doMrProp();

module/jni/main.cpp

@@ -113,9 +113,8 @@ public:
                 LOGD("Invoking the companion was successful.");
             else
             {
-                LOGW("Invoking the companion failed. Performing operations in Zygote context!");
+                LOGW("Invoking the companion failed. Functionality will be limited in Zygote context!");
                 doUnmount();
-                doRemount();
             }
 
             doHideZygisk();
@@ -165,6 +164,7 @@ void zygisk_companion_handler(int fd)
             {
                 doUnmount();
                 doRemount();
+                doMrProp();
             }));
     }();
 

module/jni/modules.cpp

@@ -1,10 +1,18 @@
 #include <string>
+#include <string_view>
 #include <set>
+#include <atomic>
 #include <unordered_map>
 #include <cstdint>
 #include <sys/mount.h>
 #include <elfio/elfio.hpp>
 
+// These includes are from the system_properties submodule, not NDK!
+#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
+#include <api/system_properties.h>
+#include <api/_system_properties.h>
+#include <system_properties/prop_info.h>
+
 #include "zygisk.hpp"
 #include "logging.hpp"
 #include "map_parser.hpp"
@@ -159,3 +167,53 @@ void doHideZygisk()
         LOGD("libnativebridge.so had_error was reset.");
     }
 }
+
+void doMrProp()
+{
+    static bool isInitialized = false;
+    static int resetCount = 0;
+    if (!isInitialized)
+    {
+        isInitialized = __system_properties_init() == 0;
+    }
+
+    if (!isInitialized)
+    {
+        LOGE("Could not initialize system_properties!");
+        return;
+    }
+
+    int ret = __system_property_foreach(
+        [](const prop_info *pi, void *)
+        {
+            if (std::string_view(pi->name).starts_with("ro.") && !pi->is_long())
+            {
+                auto serial = std::atomic_load_explicit(&pi->serial, std::memory_order_relaxed);
+
+                // Well this is a bit dangerous
+                bool shouldReset = (serial & 0xFF) != 0;
+                auto length = strlen(pi->value);
+
+                if (!shouldReset)
+                {
+                    for (size_t i = length; i < PROP_VALUE_MAX; i++)
+                    {
+                        if (pi->value[i] != 0)
+                        {
+                            shouldReset = true;
+                            break;
+                        }
+                    }
+                }
+
+                if (shouldReset)
+                {
+                    resetCount++;
+                    __system_property_update(const_cast<prop_info *>(pi), pi->value, length);
+                }
+            }
+        },
+        nullptr);
+
+    LOGD("__system_property_foreach returned %d. resetCount=%d", ret, resetCount);
+}