feat(module): add supervisor daemon with leak-safe restart and lifecycle scripts

Fork-based supervisor ensures the interceptor process survives crashes.
pingBinder() liveness check on pre-transact returns DEAD_OBJECT to
callers when interceptor is down, preventing real TEE state from leaking
during the restart window.

action.sh clears persistent key storage via KSU Action button.
uninstall.sh kills daemon processes and removes module artifacts while
preserving target.txt and keybox configuration.

app/build.gradle.kts

@@ -116,7 +116,7 @@ androidComponents {
                     )
                 ) {
                     into("lib") // Place them in the 'lib' subfolder of the staging directory.
-                    include("**/libinject.so", "**/libTEESimulator.so")
+                    include("**/libinject.so", "**/libTEESimulator.so", "**/libsupervisor.so")
                 }
 
                 // Now, copy and process the files from 'module' directory.

app/src/main/cpp/CMakeLists.txt

@@ -22,6 +22,9 @@ add_executable(libinject.so inject/main.cpp inject/utils.cpp)
 target_include_directories(libinject.so PUBLIC include)
 target_link_libraries(libinject.so PRIVATE lsplt_static)
 
+add_executable(libsupervisor.so supervisor.cpp)
+target_link_libraries(libsupervisor.so PRIVATE log)
+
 add_library(${CMAKE_PROJECT_NAME} SHARED binder_interceptor.cpp)
 target_include_directories(${CMAKE_PROJECT_NAME} PUBLIC external/linux-kernel/include include)
 target_link_libraries(${CMAKE_PROJECT_NAME} PRIVATE binder lsplt_static utils)

app/src/main/cpp/binder_interceptor.cpp

@@ -592,9 +592,16 @@ bool BinderInterceptor::processInterceptedTransaction(uint64_t tx_id, sp<BBinder
     Parcel pre_req, pre_resp;
     writeTransactionData(pre_req, tx_id, target, code, flags, request);
 
-    if (callback->transact(intercept::kPreTransact, pre_req, &pre_resp) != OK) {
-        LOGW("[TX_ID: %" PRIu64 "] Pre-transaction callback failed. Forwarding original call.", tx_id);
-        return false; // Callback failed, proceed as if not intercepted
+    status_t pre_status = callback->transact(intercept::kPreTransact, pre_req, &pre_resp);
+    if (pre_status != OK) {
+        // Block when interceptor is dead to prevent privacy leak to third-party apps
+        if (callback->pingBinder() != OK) {
+            LOGE("[TX_ID: %" PRIu64 "] Interceptor DEAD. Blocking to prevent attestation leak.", tx_id);
+            result = DEAD_OBJECT;
+            return true;
+        }
+        LOGW("[TX_ID: %" PRIu64 "] Pre-transaction callback failed (not dead). Forwarding.", tx_id);
+        return false;
     }
 
     int32_t action = pre_resp.readInt32();
@@ -647,7 +654,8 @@ bool BinderInterceptor::processInterceptedTransaction(uint64_t tx_id, sp<BBinder
         VALIDATE_STATUS(tx_id, post_req.appendFrom(reply, 0, reply_size));
     }
 
-    if (callback->transact(intercept::kPostTransact, post_req, &post_resp) == OK) {
+    status_t post_status = callback->transact(intercept::kPostTransact, post_req, &post_resp);
+    if (post_status == OK) {
         int32_t post_action = post_resp.readInt32();
         if (post_action == intercept::kActionOverrideReply && reply) {
             result = post_resp.readInt32(); // Read new status

app/src/main/cpp/supervisor.cpp

@@ -0,0 +1,57 @@
+// Fork-based supervisor for instant daemon restart
+#include <unistd.h>
+#include <sys/wait.h>
+#include <sys/prctl.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+
+static volatile sig_atomic_t should_exit = 0;
+
+static void signal_handler(int sig) {
+    should_exit = 1;
+}
+
+int main(int argc, char *argv[]) {
+    if (argc < 2) {
+        fprintf(stderr, "Usage: %s <daemon> [args...]\n", argv[0]);
+        return 1;
+    }
+
+    // Forward termination signals to exit cleanly
+    signal(SIGTERM, signal_handler);
+    signal(SIGINT, signal_handler);
+
+    const char *daemon_path = argv[1];
+    char **daemon_argv = &argv[1];
+
+    while (!should_exit) {
+        pid_t pid = fork();
+
+        if (pid < 0) {
+            perror("fork failed");
+            usleep(100000); // 100ms backoff on fork failure
+            continue;
+        }
+
+        if (pid == 0) {
+            // Child: become the daemon
+            prctl(PR_SET_PDEATHSIG, SIGKILL); // Die if parent dies
+            execv(daemon_path, daemon_argv);
+            perror("execv failed");
+            _exit(127);
+        }
+
+        // Parent: wait for child to exit
+        int status;
+        waitpid(pid, &status, 0);
+
+        if (should_exit) break;
+
+        // Instant restart - no delay
+    }
+
+    return 0;
+}