Use LSPlt only for Android 15

For non-stripped `libart.so` ELFs, their plt tables are too small for inline hook.
JingMatrix · Aug 31, 2024 · b42e3b4 · b42e3b4
1 parent 30043e2
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Showing 4 changed files with 33 additions and 19 deletions.
diff --git a/README.md b/README.md
@@ -58,8 +58,8 @@ You can contribute translation [here](https://crowdin.com/project/lsposed_jingma
 - [Magisk](https://github.com/topjohnwu/Magisk/): makes all these possible
 - [Riru](https://github.com/RikkaApps/Riru): provides a way to inject code into zygote process
 - [XposedBridge](https://github.com/rovo89/XposedBridge): the OG Xposed framework APIs
-- [LSPlt](https://github.com/LSPosed/LSPlt): used for `libart` inline hooking
-- [Dobby](https://github.com/chiteroman/Dobby): used for `native_api` inline hooking
+- [LSPlt](https://github.com/LSPosed/LSPlt): used for (Android 15) `libart` inline hooking
+- [Dobby](https://github.com/chiteroman/Dobby): used for fallback and `native_api` inline hooking
 - [LSPlant](https://github.com/JingMatrix/LSPlant): the core ART hooking framework
 - [EdXposed](https://github.com/ElderDrivers/EdXposed): fork source
 - ~[SandHook](https://github.com/ganyao114/SandHook/): ART hooking framework for SandHook variant~

diff --git a/core/src/main/jni/include/elf_util.h b/core/src/main/jni/include/elf_util.h
@@ -74,6 +74,10 @@ namespace SandHook {
             return base != nullptr;
         }
 
+        bool isStripped() const {
+            return debugdata_offset != 0 && debugdata_size != 0;
+        }
+
         const std::string name() const {
             return elf;
         }

diff --git a/core/src/main/jni/include/native_util.h b/core/src/main/jni/include/native_util.h
@@ -80,23 +80,30 @@ static dev_t dev = 0;
 static ino_t inode = 0;
 static std::vector<std::pair<std::string_view, void **>> plt_hook_saved = {};
 
-inline int HookArtFunction(void *original, void *callback, void **backup, bool save = true) {
-    auto symbol = *reinterpret_cast<std::string_view *>(original);
-    if (dev == 0 || inode == 0) {
-        auto libart_path = GetArt()->name();
-        for (auto map : lsplt::MapInfo::Scan()) {
-            if (map.path == libart_path) {
-                inode = map.inode;
-                dev = map.dev;
-                break;
+inline int HookArtFunction(void *art_symbol, void *callback, void **backup, bool save = true) {
+    auto symbol = *reinterpret_cast<std::string_view *>(art_symbol);
+
+    if (GetArt()->isStripped()) {
+        if (dev == 0 || inode == 0) {
+            auto libart_path = GetArt()->name();
+            for (auto map : lsplt::MapInfo::Scan()) {
+                if (map.path == libart_path) {
+                    inode = map.inode;
+                    dev = map.dev;
+                    break;
+                }
             }
         }
+
+        auto result =
+            lsplt::RegisterHook(dev, inode, symbol, callback, backup) && lsplt::CommitHook();
+        if (result && *backup != nullptr) {
+            if (save) plt_hook_saved.emplace_back(symbol, backup);
+            return 0;
+        }
     }
 
-    auto result = lsplt::RegisterHook(dev, inode, symbol, callback, backup) && lsplt::CommitHook();
-    if (result && *backup != nullptr) {
-        if (save) plt_hook_saved.emplace_back(symbol, backup);
-    } else if (auto addr = GetArt()->getSymbAddress(symbol); addr) {
+    if (auto addr = GetArt()->getSymbAddress(symbol); addr) {
         Dl_info info;
         if (dladdr(addr, &info) && info.dli_sname != nullptr && info.dli_sname == symbol)
             HookFunction(addr, callback, backup);
@@ -107,10 +114,13 @@ inline int HookArtFunction(void *original, void *callback, void **backup, bool s
 }
 
 inline int UnhookArtFunction(void *original) {
-    std::string_view func_name = *reinterpret_cast<std::string_view *>(original);
-    auto hook_iter = std::find_if(plt_hook_saved.begin(), plt_hook_saved.end(),
-                                  [func_name](auto record) { return record.first == func_name; });
+    Dl_info info;
 
+    if (!dladdr(original, &info) || info.dli_sname != nullptr) return 1;
+    if (!GetArt()->isStripped()) return UnhookFunction(original);
+
+    auto hook_iter = std::find_if(plt_hook_saved.begin(), plt_hook_saved.end(),
+                                  [info](auto record) { return record.first == info.dli_sname; });
     void *stub = nullptr;
     if (hook_iter != plt_hook_saved.end() &&
         HookArtFunction(original, *(hook_iter->second), &stub, false)) {

diff --git a/core/src/main/jni/src/elf_util.cpp b/core/src/main/jni/src/elf_util.cpp
@@ -58,7 +58,7 @@ ElfImg::ElfImg(std::string_view base_name) : elf(base_name) {
 
     close(fd);
     parse(header);
-    if (debugdata_offset != 0 && debugdata_size != 0) {
+    if (isStripped()) {
         if (xzdecompress()) {
             header_debugdata = reinterpret_cast<ElfW(Ehdr) *>(elf_debugdata.data());
             parse(header_debugdata);