From ed95043d6433c5900984f24dbb101bba78109775 Mon Sep 17 00:00:00 2001 From: Jeff Vander Stoep Date: Thu, 6 Jul 2017 22:29:12 -0700 Subject: [PATCH] configstore: sandbox with seccomp filter Configstore HAL is accessible to third party apps and thus requires a tight sandbox that reflects the limited system access this HAL needs. We use two primary mechanisms to sandbox configstore, selinux and seccomp, with the goal of restricting its access to userspace and the kernel. The addition of a seccomp filter is primarily aimed at reducing the kernel's attack surface that is reachable by configstore HAL. Seccomp filters are architecture dependent, so filters need to be added for each architecture. This change adds a seccomp filter for arm64 and issues a non-fatal runtime warning for other architectures which still require a seccomp filter. Bug: 36453956 Test: boot Marlin and Angler. Verify that configstore is not aborting due to seccomp violations. Test: "cat proc//status | grep seccomp " returns: seccomp: 2 Which indicates that configstore is using seccomp-bpf. Change-Id: Iab014ff357b7329085a5e18a92f51838d2c72371 --- configstore/1.1/default/Android.mk | 12 +++++ .../configstore@1.1-arm64.policy | 40 +++++++++++++++++ configstore/1.1/default/service.cpp | 4 ++ minijail/Android.mk | 14 ++++++ minijail/HardwareMinijail.cpp | 45 +++++++++++++++++++ .../include/hwminijail/HardwareMinijail.h | 30 +++++++++++++ 6 files changed, 145 insertions(+) create mode 100644 configstore/1.1/default/seccomp_policy/configstore@1.1-arm64.policy create mode 100644 minijail/Android.mk create mode 100644 minijail/HardwareMinijail.cpp create mode 100644 minijail/include/hwminijail/HardwareMinijail.h diff --git a/configstore/1.1/default/Android.mk b/configstore/1.1/default/Android.mk index ac3d8b039d..58b67c1525 100644 --- a/configstore/1.1/default/Android.mk +++ b/configstore/1.1/default/Android.mk @@ -3,6 +3,7 @@ LOCAL_PATH := $(call my-dir) ################################################################################ include $(CLEAR_VARS) LOCAL_MODULE := android.hardware.configstore@1.1-service +LOCAL_REQUIRED_MODULES_arm64 := configstore@1.1.policy LOCAL_PROPRIETARY_MODULE := true LOCAL_MODULE_CLASS := EXECUTABLES LOCAL_MODULE_RELATIVE_PATH := hw @@ -17,7 +18,18 @@ LOCAL_SHARED_LIBRARIES := \ libhidlbase \ libhidltransport \ libbase \ + libhwminijail \ liblog \ libutils \ include $(BUILD_EXECUTABLE) + +# seccomp filter for configstore +ifeq ($(TARGET_ARCH), $(filter $(TARGET_ARCH), arm64)) +include $(CLEAR_VARS) +LOCAL_MODULE := configstore@1.1.policy +LOCAL_MODULE_CLASS := ETC +LOCAL_MODULE_PATH := $(TARGET_OUT_VENDOR)/etc/seccomp_policy +LOCAL_SRC_FILES := seccomp_policy/configstore@1.1-$(TARGET_ARCH).policy +include $(BUILD_PREBUILT) +endif diff --git a/configstore/1.1/default/seccomp_policy/configstore@1.1-arm64.policy b/configstore/1.1/default/seccomp_policy/configstore@1.1-arm64.policy new file mode 100644 index 0000000000..8c901eb8de --- /dev/null +++ b/configstore/1.1/default/seccomp_policy/configstore@1.1-arm64.policy @@ -0,0 +1,40 @@ +# Copyright (C) 2017 The Android Open Source Project +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +futex: 1 +# ioctl: arg1 == BINDER_WRITE_READ +ioctl: arg1 == 0xc0306201 +ioctl: 1 +# prctl: arg0 == PR_SET_NAME || arg0 == PR_SET_VMA || arg0 == PR_SET_TIMERSLACK +prctl: arg0 == 15 || arg0 == 0x53564d41 || arg0 == 29 +openat: 1 +mmap: 1 +mprotect: 1 +close: 1 +getuid: 1 +read: 1 +faccessat: 1 +write: 1 +fstat: 1 +clone: 1 +munmap: 1 +lseek: 1 +sigaltstack: 1 +writev: 1 +setpriority: 1 +restart_syscall: 1 +exit: 1 +exit_group: 1 +rt_sigreturn: 1 +getrlimit: 1 diff --git a/configstore/1.1/default/service.cpp b/configstore/1.1/default/service.cpp index 3a4cd3fd67..d277e5d415 100644 --- a/configstore/1.1/default/service.cpp +++ b/configstore/1.1/default/service.cpp @@ -18,6 +18,7 @@ #include #include +#include #include "SurfaceFlingerConfigs.h" @@ -25,6 +26,7 @@ using android::hardware::configureRpcThreadpool; using android::hardware::joinRpcThreadpool; using android::hardware::configstore::V1_1::ISurfaceFlingerConfigs; using android::hardware::configstore::V1_1::implementation::SurfaceFlingerConfigs; +using android::hardware::SetupMinijail; using android::sp; using android::status_t; using android::OK; @@ -33,6 +35,8 @@ int main() { // TODO(b/34857894): tune the max thread count. configureRpcThreadpool(10, true); + SetupMinijail("/vendor/etc/seccomp_policy/configstore@1.1.policy"); + sp surfaceFlingerConfigs = new SurfaceFlingerConfigs; status_t status = surfaceFlingerConfigs->registerAsService(); LOG_ALWAYS_FATAL_IF(status != OK, "Could not register ISurfaceFlingerConfigs"); diff --git a/minijail/Android.mk b/minijail/Android.mk new file mode 100644 index 0000000000..272bb0ef1f --- /dev/null +++ b/minijail/Android.mk @@ -0,0 +1,14 @@ +LOCAL_PATH := $(call my-dir) + +include $(CLEAR_VARS) +LOCAL_MODULE := libhwminijail +LOCAL_PROPRIETARY_MODULE := true +LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include +LOCAL_C_INCLUDES := $(LOCAL_PATH)/include +LOCAL_SRC_FILES := HardwareMinijail.cpp + +LOCAL_SHARED_LIBRARIES := \ + libbase \ + libminijail_vendor + +include $(BUILD_SHARED_LIBRARY) diff --git a/minijail/HardwareMinijail.cpp b/minijail/HardwareMinijail.cpp new file mode 100644 index 0000000000..e6b11440c6 --- /dev/null +++ b/minijail/HardwareMinijail.cpp @@ -0,0 +1,45 @@ +// +// Copyright (C) 2017 The Android Open Source Project +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. +// + +#include +#include + +#include + +namespace android { +namespace hardware { + +void SetupMinijail(const std::string& seccomp_policy_path) { + if (access(seccomp_policy_path.c_str(), R_OK) == -1) { + LOG(WARNING) << "Could not find seccomp policy file at: " << seccomp_policy_path; + return; + } + + struct minijail* jail = minijail_new(); + if (jail == NULL) { + LOG(FATAL) << "Failed to create minijail."; + } + + minijail_no_new_privs(jail); + minijail_log_seccomp_filter_failures(jail); + minijail_use_seccomp_filter(jail); + minijail_parse_seccomp_filters(jail, seccomp_policy_path.c_str()); + minijail_enter(jail); + minijail_destroy(jail); +} + +} // namespace hardware +} // namespace android diff --git a/minijail/include/hwminijail/HardwareMinijail.h b/minijail/include/hwminijail/HardwareMinijail.h new file mode 100644 index 0000000000..8fcf007bfb --- /dev/null +++ b/minijail/include/hwminijail/HardwareMinijail.h @@ -0,0 +1,30 @@ +// +// Copyright (C) 2017 The Android Open Source Project +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. +// + +#ifndef ANDROID_HARDWARE_CONFIGSTORE_MINIJAIL_H +#define ANDROID_HARDWARE_CONFIGSTORE_MINIJAIL_H + +#include + +namespace android { +namespace hardware { + +void SetupMinijail(const std::string& seccomp_policy_path); + +} // namespace hardware +} // namespace android + +#endif // ANDROID_HARDWARE_CONFIGSTORE_UTILS_H