From fcf2c01b5599a96b968afb1528c996d9486937b0 Mon Sep 17 00:00:00 2001 From: Josh Gao Date: Thu, 31 May 2018 21:24:14 -0700 Subject: base: add support for tagged fd closure to unique_fd. Test: libbase_test Change-Id: Ibba5e60d7007265a566eb8f76021d5dbeb734532 --- base/Android.bp | 1 + base/include/android-base/unique_fd.h | 82 +++++++++++++++++++++++++++++------ base/unique_fd_test.cpp | 54 +++++++++++++++++++++++ 3 files changed, 123 insertions(+), 14 deletions(-) create mode 100644 base/unique_fd_test.cpp (limited to 'base') diff --git a/base/Android.bp b/base/Android.bp index 3d80d9719..46a023342 100644 --- a/base/Android.bp +++ b/base/Android.bp @@ -135,6 +135,7 @@ cc_test { "strings_test.cpp", "test_main.cpp", "test_utils_test.cpp", + "unique_fd_test.cpp", ], target: { android: { diff --git a/base/include/android-base/unique_fd.h b/base/include/android-base/unique_fd.h index 6cfcd3fb0..057f462e5 100644 --- a/base/include/android-base/unique_fd.h +++ b/base/include/android-base/unique_fd.h @@ -42,10 +42,29 @@ // // unique_fd is also known as ScopedFd/ScopedFD/scoped_fd; mentioned here to help // you find this class if you're searching for one of those names. + +#if defined(__BIONIC__) +#include +#endif + namespace android { namespace base { struct DefaultCloser { +#if defined(__BIONIC__) + static void Tag(int fd, void* old_addr, void* new_addr) { + uint64_t old_tag = android_fdsan_create_owner_tag(ANDROID_FDSAN_OWNER_TYPE_UNIQUE_FD, + reinterpret_cast(old_addr)); + uint64_t new_tag = android_fdsan_create_owner_tag(ANDROID_FDSAN_OWNER_TYPE_UNIQUE_FD, + reinterpret_cast(new_addr)); + android_fdsan_exchange_owner_tag(fd, old_tag, new_tag); + } + static void Close(int fd, void* addr) { + uint64_t tag = android_fdsan_create_owner_tag(ANDROID_FDSAN_OWNER_TYPE_UNIQUE_FD, + reinterpret_cast(addr)); + android_fdsan_close_with_tag(fd, tag); + } +#else static void Close(int fd) { // Even if close(2) fails with EINTR, the fd will have been closed. // Using TEMP_FAILURE_RETRY will either lead to EBADF or closing someone @@ -53,40 +72,75 @@ struct DefaultCloser { // http://lkml.indiana.edu/hypermail/linux/kernel/0509.1/0877.html ::close(fd); } +#endif }; template class unique_fd_impl final { public: - unique_fd_impl() : value_(-1) {} + unique_fd_impl() {} - explicit unique_fd_impl(int value) : value_(value) {} + explicit unique_fd_impl(int fd) { reset(fd); } ~unique_fd_impl() { reset(); } - unique_fd_impl(unique_fd_impl&& other) : value_(other.release()) {} + unique_fd_impl(unique_fd_impl&& other) { reset(other.release()); } unique_fd_impl& operator=(unique_fd_impl&& s) { - reset(s.release()); + int fd = s.fd_; + s.fd_ = -1; + reset(fd, &s); return *this; } - void reset(int new_value = -1) { - if (value_ != -1) { - Closer::Close(value_); - } - value_ = new_value; - } + void reset(int new_value = -1) { reset(new_value, nullptr); } - int get() const { return value_; } + int get() const { return fd_; } operator int() const { return get(); } int release() __attribute__((warn_unused_result)) { - int ret = value_; - value_ = -1; + tag(fd_, this, nullptr); + int ret = fd_; + fd_ = -1; return ret; } private: - int value_; + void reset(int new_value, void* previous_tag) { + if (fd_ != -1) { + close(fd_, this); + } + + fd_ = new_value; + if (new_value != -1) { + tag(new_value, previous_tag, this); + } + } + + int fd_ = -1; + + // Template magic to use Closer::Tag if available, and do nothing if not. + // If Closer::Tag exists, this implementation is preferred, because int is a better match. + // If not, this implementation is SFINAEd away, and the no-op below is the only one that exists. + template + static auto tag(int fd, void* old_tag, void* new_tag) + -> decltype(T::Tag(fd, old_tag, new_tag), void()) { + T::Tag(fd, old_tag, new_tag); + } + + template + static void tag(long, void*, void*) { + // No-op. + } + + // Same as above, to select between Closer::Close(int) and Closer::Close(int, void*). + template + static auto close(int fd, void* tag_value) -> decltype(T::Close(fd, tag_value), void()) { + T::Close(fd, tag_value); + } + + template + static auto close(int fd, void*) -> decltype(T::Close(fd), void()) { + T::Close(fd); + } unique_fd_impl(const unique_fd_impl&); void operator=(const unique_fd_impl&); diff --git a/base/unique_fd_test.cpp b/base/unique_fd_test.cpp new file mode 100644 index 000000000..3fdf12a30 --- /dev/null +++ b/base/unique_fd_test.cpp @@ -0,0 +1,54 @@ +/* + * Copyright (C) 2018 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 "android-base/unique_fd.h" + +#include + +#include +#include +#include + +using android::base::unique_fd; + +TEST(unique_fd, unowned_close) { +#if defined(__BIONIC__) + unique_fd fd(open("/dev/null", O_RDONLY)); + EXPECT_DEATH(close(fd.get()), "incorrect tag"); +#endif +} + +TEST(unique_fd, untag_on_release) { + unique_fd fd(open("/dev/null", O_RDONLY)); + close(fd.release()); +} + +TEST(unique_fd, move) { + unique_fd fd(open("/dev/null", O_RDONLY)); + unique_fd fd_moved = std::move(fd); + ASSERT_EQ(-1, fd.get()); + ASSERT_GT(fd_moved.get(), -1); +} + +TEST(unique_fd, unowned_close_after_move) { +#if defined(__BIONIC__) + unique_fd fd(open("/dev/null", O_RDONLY)); + unique_fd fd_moved = std::move(fd); + ASSERT_EQ(-1, fd.get()); + ASSERT_GT(fd_moved.get(), -1); + EXPECT_DEATH(close(fd_moved.get()), "incorrect tag"); +#endif +} -- cgit v1.2.3