refactor(native): remap sections

Signed-off-by: rhunk <101876869+rhunk@users.noreply.github.com>

core/src/main/kotlin/me/rhunk/snapenhance/core/SnapEnhance.kt

@@ -5,6 +5,7 @@ import android.app.Application
 import android.content.Context
 import android.content.res.Resources
 import android.os.Build
+import dalvik.system.BaseDexClassLoader
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
@@ -27,6 +28,7 @@ import me.rhunk.snapenhance.core.util.LSPatchUpdater
 import me.rhunk.snapenhance.core.util.hook.HookAdapter
 import me.rhunk.snapenhance.core.util.hook.HookStage
 import me.rhunk.snapenhance.core.util.hook.hook
+import me.rhunk.snapenhance.core.util.hook.hookConstructor
 import kotlin.system.exitProcess
 import kotlin.system.measureTimeMillis
 
@@ -205,6 +207,9 @@ class SnapEnhance {
                         request.canceled = canceled
                     }
                 }
+                BaseDexClassLoader::class.java.hookConstructor(HookStage.AFTER) {
+                    appContext.native.hideAnonymousDexFiles()
+                }
                 appContext.reloadNativeConfig()
             }
         }.also { unhook = { it.unhook() } }

native/jni/src/dobby_helper.h

@@ -9,5 +9,6 @@ static pthread_mutex_t hook_mutex = PTHREAD_MUTEX_INITIALIZER;
 static void inline SafeHook(void *addr, void *hook, void **original) {
     pthread_mutex_lock(&hook_mutex);
     DobbyHook(addr, hook, original);
+    mprotect((void *)((uintptr_t) *original & PAGE_MASK), PAGE_SIZE, PROT_EXEC);
     pthread_mutex_unlock(&hook_mutex);
 }

native/jni/src/library.cpp

@@ -4,9 +4,9 @@
 #include <vector>
 #include <thread>
 
-#include "dobby_helper.h"
 #include "logger.h"
 #include "common.h"
+#include "dobby_helper.h"
 #include "hooks/unary_call.h"
 #include "hooks/fstat_hook.h"
 #include "hooks/sqlite_mutex.h"
@@ -93,6 +93,16 @@ void JNICALL lock_database(JNIEnv *env, jobject, jstring database_name, jobject
     }
 }
 
+void JNICALL hide_anonymous_dex_files(JNIEnv *, jobject) {
+    util::remap_sections([](const std::string &line, size_t size) {
+        return (
+            (size == PAGE_SIZE && line.find("r-xp 00000000") != std::string::npos && line.find("[v") == std::string::npos) ||
+            line.find("dalvik-DEX") != std::string::npos ||
+            line.find("dalvik-classes") != std::string::npos
+        );
+    });
+}
+
 extern "C" JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *_) {
     common::java_vm = vm;
     JNIEnv *env = nullptr;
@@ -104,8 +114,12 @@ extern "C" JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *_) {
     methods.push_back({"lockDatabase", "(Ljava/lang/String;Ljava/lang/Runnable;)V", (void *)lock_database});
     methods.push_back({"setComposerLoader", "(Ljava/lang/String;)V", (void *) ComposerHook::setComposerLoader});
     methods.push_back({"composerEval", "(Ljava/lang/String;)Ljava/lang/String;",(void *) ComposerHook::composerEval});
+    methods.push_back({"hideAnonymousDexFiles", "()V", (void *)hide_anonymous_dex_files});
 
     env->RegisterNatives(env->FindClass(std::string(BUILD_NAMESPACE "/NativeLib").c_str()), methods.data(), methods.size());
-    util::remap_sections(BUILD_PACKAGE);
+    util::remap_sections([](const std::string &line, size_t size) {
+        return line.find(BUILD_PACKAGE) != std::string::npos;
+    });
+    hide_anonymous_dex_files(env, nullptr);
     return JNI_VERSION_1_6;
 }

native/jni/src/util.h

@@ -52,14 +52,13 @@ namespace util {
         return { start_offset, end_offset - start_offset };
     }
 
-    static void remap_sections(const char* path) {
+    static void remap_sections(std::function<bool(const std::string &, size_t)> filter) {
         char buff[256];
         auto maps = fopen("/proc/self/maps", "rt");
 
         while (fgets(buff, sizeof buff, maps) != NULL) {
             int len = strlen(buff);
             if (len > 0 && buff[len - 1] == '\n') buff[--len] = '\0';
-            if (strstr(buff, path) == nullptr) continue;
 
             size_t start, end, offset;
             char flags[4];
@@ -67,7 +66,7 @@ namespace util {
             if (sscanf(buff, "%zx-%zx %c%c%c%c %zx", &start, &end,
                        &flags[0], &flags[1], &flags[2], &flags[3], &offset) != 7) continue;
 
-            LOGD("Remapping 0x%zx-0x%zx", start, end);
+            if (!filter(buff, end - start)) continue;
 
             auto section_size = end - start;
             auto section_ptr = mmap(0, section_size, PROT_READ | PROT_EXEC | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
@@ -84,7 +83,11 @@ namespace util {
                 break;
             }
 
-            mprotect((void *)start, section_size, (flags[0] == 'r' ? PROT_READ : 0) | (flags[1] == 'w' ? PROT_WRITE : 0) | (flags[2] == 'x' ? PROT_EXEC : 0));
+            auto new_prot = (flags[0] == 'r' ? PROT_READ : 0) | (flags[1] == 'w' ? PROT_WRITE : 0) | (flags[2] == 'x' ? PROT_EXEC : 0);
+            if (new_prot & PROT_EXEC) {
+                new_prot &= ~PROT_READ;
+            }
+            mprotect((void *)start, section_size, new_prot);
         }
         fclose(maps);
     }

native/src/main/kotlin/me/rhunk/snapenhance/nativelib/NativeLib.kt

@@ -59,4 +59,5 @@ class NativeLib {
     private external fun lockDatabase(name: String, callback: Runnable)
     external fun setComposerLoader(code: String)
     external fun composerEval(code: String): String?
+    external fun hideAnonymousDexFiles()
 }