diff options
| -rw-r--r-- | ashmemd_client.cpp | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/ashmemd_client.cpp b/ashmemd_client.cpp index 3380209..a9041a0 100644 --- a/ashmemd_client.cpp +++ b/ashmemd_client.cpp @@ -17,6 +17,7 @@ #include <android-base/logging.h> #include <android/ashmemd/IAshmemDeviceService.h> #include <binder/IServiceManager.h> +#include <cutils/android_filesystem_config.h> using android::IBinder; using android::IServiceManager; @@ -27,7 +28,25 @@ using android::os::ParcelFileDescriptor; namespace android { namespace ashmemd { +static bool checkBinderAccess() { + // Isolated apps are potentially subject to seccomp policy that restricts use of access() + // (b/129483782). However, apps always have access to binder, so return true. + auto uid = getuid() % AID_USER; + if (AID_ISOLATED_START <= uid && uid <= AID_ISOLATED_END) { + return true; + } + if (access("/dev/binder", R_OK | W_OK) == 0) { + return true; + } + return false; +} + sp<IAshmemDeviceService> getAshmemService() { + // Calls to defaultServiceManager() crash the process if it doesn't have appropriate + // binder permissions. Check these permissions proactively. + if (!checkBinderAccess()) { + return nullptr; + } sp<IServiceManager> sm = android::defaultServiceManager(); sp<IBinder> binder = sm->checkService(String16("ashmem_device_service")); return interface_cast<IAshmemDeviceService>(binder); |