add: CSOLoader

This commit implements the use of CSOLoader in ReZygisk. In a long time, ReZygisk relied on system linker to load Zygisk modules, bringing numerous detections due to gigantic amount of traces left inside it. To simplify and future-proof ReZygisk hiding, while improving compatibility with new Android versions and different devices, CSOLoader links all necessary parts, and provides the necessary information through linker APIs for the loaded shared libraries.

Author: ThePedroo

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "LSPlt"]
 	path = loader/src/external/lsplt
 	url = https://github.com/PerformanC/LSPlt
+[submodule "CSOLoader"]
+	path = loader/src/external/csoloader
+	url = https://github.com/ThePedroo/CSOLoader

README.md

@@ -22,11 +22,12 @@ The Zygisk Next developers are famous and trusted in the Android community, howe
 |-----------------|----------------------------------------|
 | `Android NDK`   | Native Development Kit for Android     |
 
-### C++ Dependencies
+### C Dependencies
 
-| Dependency | Description                   |
-|------------|-------------------------------|
-| `lsplt`    | Simple PLT Hook for Android   |
+| Dependency  | Description                   |
+|-------------|-------------------------------|
+| `LSPLt`     | Simple PLT Hook for Android   |
+| `CSOLoader` | SOTA Linux custom linker      |
 
 ## Installation
 

loader/src/CMakeLists.txt

@@ -15,7 +15,7 @@ target_link_libraries(common log)
 aux_source_directory(injector INJECTOR_SRC_LIST)
 add_library(zygisk SHARED ${INJECTOR_SRC_LIST})
 target_include_directories(zygisk PRIVATE include)
-target_link_libraries(zygisk cxx::cxx log common lsplt_static)
+target_link_libraries(zygisk cxx::cxx log common lsplt_static csoloader)
 
 aux_source_directory(ptracer PTRACER_SRC_LIST)
 add_executable(libzygisk_ptrace.so ${PTRACER_SRC_LIST})

loader/src/external/CMakeLists.txt

@@ -2,3 +2,4 @@ project(external)
 
 OPTION(LSPLT_BUILD_SHARED OFF)
 add_subdirectory(lsplt/lsplt/src/main/jni)
+add_subdirectory(csoloader)

loader/src/external/csoloader

@@ -25,8 +25,8 @@ void entry(void *addr, size_t size) {
     LOGD("start plt hooking");
     hook_functions();
 
-    solist_drop_so_path(addr, true);
-    solist_reset_counters(1, 1);
+    solist_drop_so_path(addr);
+    solist_reset_counters(1);
 
     struct kernel_version version = parse_kversion();
     if (version.major > 3 || (version.major == 3 && version.minor >= 8)) {

loader/src/injector/entry.cpp

@@ -715,52 +715,35 @@ bool load_modules_only() {
   for (size_t i = 0; i < ms.modules_count; i++) {
     char *lib_path = ms.modules[i];
 
-    void *handle = dlopen(lib_path, RTLD_NOW);
-    if (!handle) {
-      LOGE("Failed to load module [%s]: %s", lib_path, dlerror());
+    if (!csoloader_load(&zygisk_modules[zygisk_module_length].lib, lib_path)) {
+      LOGE("Failed to load module [%s]", lib_path);
 
       continue;
     }
 
-    void *entry = dlsym(handle, "zygisk_module_entry");
+    void *entry = csoloader_get_symbol(&zygisk_modules[zygisk_module_length].lib, "zygisk_module_entry");
     if (!entry) {
-      LOGE("Failed to find entry point in module [%s]: %s", lib_path, dlerror());
+      LOGE("Failed to find entry point in module [%s]", lib_path);
 
-      dlclose(handle);
+      csoloader_unload(&zygisk_modules[zygisk_module_length].lib);
 
       continue;
     }
 
     zygisk_modules[zygisk_module_length].api.register_module = rezygisk_module_register;
     zygisk_modules[zygisk_module_length].api.impl = (void *)zygisk_module_length;
 
-    zygisk_modules[zygisk_module_length].handle = handle;
     zygisk_modules[zygisk_module_length].zygisk_module_entry = (void (*)(void *, void *))entry;
 
-    zygisk_modules[zygisk_module_length].base = solist_get_base(entry);
-    zygisk_modules[zygisk_module_length].size = solist_get_size(entry);
-
-    zygisk_modules[zygisk_module_length].deconstructors = solist_get_deconstructors(entry);
-
-    LOGD("Loaded module [%s]. Entry: %p, Base: %p, Size: %zu, Deconstructors: fini_func=%p, fini_array=%p (size: %zu)",
+    LOGD("Loaded module [%s]. Entry: %p",
          lib_path,
-         entry,
-         zygisk_modules[zygisk_module_length].base,
-         zygisk_modules[zygisk_module_length].size,
-         zygisk_modules[zygisk_module_length].deconstructors.fini_func,
-         zygisk_modules[zygisk_module_length].deconstructors.fini_array,
-         zygisk_modules[zygisk_module_length].deconstructors.fini_array_size);
+         entry);
 
     zygisk_modules[zygisk_module_length].unload = false;
 
-    /* INFO: Early removal to avoid gaps in solist */
-    solist_drop_so_path(entry, false);
-
     zygisk_module_length++;
   }
 
-  solist_reset_counters(zygisk_module_length, zygisk_module_length);
-
   free_modules(&ms);
 
   return true;
@@ -786,25 +769,10 @@ void ZygiskContext::run_modules_post() {
         if (flags[APP_SPECIALIZE]) rezygisk_module_call_post_app_specialize(m, args.app);
         else if (flags[SERVER_FORK_AND_SPECIALIZE]) rezygisk_module_call_post_server_specialize(m, args.server);
 
-        /* INFO: If module is unloaded by dlclose, there's no need to
-                   hide it from soinfo manually. */
         if (!m->unload) continue;
 
-        /* INFO: Deconstructors are called in the inverted order, and following fini array then fini
-                    function order. It must not change. */
-        for (size_t j = m->deconstructors.fini_array_size; j > 0; j--) {
-            void (*destructor)(void) = m->deconstructors.fini_array[j - 1];
-            if (destructor) {
-                LOGD("Calling destructor %p for module %p", (void *)destructor, (void *)m->zygisk_module_entry);
-
-                destructor();
-            }
-        }
-
-        if (m->deconstructors.fini_func) m->deconstructors.fini_func();
-
-        if (munmap(m->base, m->size) == -1) {
-            PLOGE("Failed to unmap module library at %p with size %zu", m->base, m->size);
+        if (csoloader_unload(&m->lib) == false) {
+            LOGE("Failed to unload module library");
 
             continue;
         }

loader/src/injector/hook.cpp

@@ -1,6 +1,8 @@
 #ifndef MODULE_H
 #define MODULE_H
 
+#include <csoloader.h>
+
 #include "logging.h"
 #include "solist.h"
 
@@ -146,14 +148,9 @@ struct rezygisk_module {
   struct rezygisk_abi abi;
   struct rezygisk_api api;
 
-  void *handle;
+  struct csoloader lib;
   void (*zygisk_module_entry)(void *, void *);
 
-  void *base;
-  size_t size;
-
-  struct soinfo_deconstructor deconstructors;
-
   bool unload;
 };