| /* |
| * 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. |
| */ |
| |
| #ifndef BPF_BPFMAP_H |
| #define BPF_BPFMAP_H |
| |
| #include <linux/bpf.h> |
| |
| #include <android-base/result.h> |
| #include <android-base/stringprintf.h> |
| #include <android-base/unique_fd.h> |
| #include <utils/Log.h> |
| #include "bpf/BpfUtils.h" |
| |
| namespace android { |
| namespace bpf { |
| |
| // This is a class wrapper for eBPF maps. The eBPF map is a special in-kernel |
| // data structure that stores data in <Key, Value> pairs. It can be read/write |
| // from userspace by passing syscalls with the map file descriptor. This class |
| // is used to generalize the procedure of interacting with eBPF maps and hide |
| // the implementation detail from other process. Besides the basic syscalls |
| // wrapper, it also provides some useful helper functions as well as an iterator |
| // nested class to iterate the map more easily. |
| // |
| // NOTE: A kernel eBPF map may be accessed by both kernel and userspace |
| // processes at the same time. Or if the map is pinned as a virtual file, it can |
| // be obtained by multiple eBPF map class object and accessed concurrently. |
| // Though the map class object and the underlying kernel map are thread safe, it |
| // is not safe to iterate over a map while another thread or process is deleting |
| // from it. In this case the iteration can return duplicate entries. |
| template <class Key, class Value> |
| class BpfMap { |
| public: |
| BpfMap<Key, Value>() {}; |
| |
| protected: |
| // flag must be within BPF_OBJ_FLAG_MASK, ie. 0, BPF_F_RDONLY, BPF_F_WRONLY |
| BpfMap<Key, Value>(const char* pathname, uint32_t flags) { |
| int map_fd = mapRetrieve(pathname, flags); |
| if (map_fd >= 0) mMapFd.reset(map_fd); |
| } |
| |
| public: |
| explicit BpfMap<Key, Value>(const char* pathname) : BpfMap<Key, Value>(pathname, 0) {} |
| |
| BpfMap<Key, Value>(bpf_map_type map_type, uint32_t max_entries, uint32_t map_flags = 0) { |
| int map_fd = createMap(map_type, sizeof(Key), sizeof(Value), max_entries, map_flags); |
| if (map_fd >= 0) mMapFd.reset(map_fd); |
| } |
| |
| base::Result<Key> getFirstKey() const { |
| Key firstKey; |
| if (getFirstMapKey(mMapFd, &firstKey)) { |
| return ErrnoErrorf("Get firstKey map {} failed", mMapFd.get()); |
| } |
| return firstKey; |
| } |
| |
| base::Result<Key> getNextKey(const Key& key) const { |
| Key nextKey; |
| if (getNextMapKey(mMapFd, &key, &nextKey)) { |
| return ErrnoErrorf("Get next key of map {} failed", mMapFd.get()); |
| } |
| return nextKey; |
| } |
| |
| base::Result<void> writeValue(const Key& key, const Value& value, uint64_t flags) { |
| if (writeToMapEntry(mMapFd, &key, &value, flags)) { |
| return ErrnoErrorf("Write to map {} failed", mMapFd.get()); |
| } |
| return {}; |
| } |
| |
| base::Result<Value> readValue(const Key key) const { |
| Value value; |
| if (findMapEntry(mMapFd, &key, &value)) { |
| return ErrnoErrorf("Read value of map {} failed", mMapFd.get()); |
| } |
| return value; |
| } |
| |
| base::Result<void> deleteValue(const Key& key) { |
| if (deleteMapEntry(mMapFd, &key)) { |
| return ErrnoErrorf("Delete entry from map {} failed", mMapFd.get()); |
| } |
| return {}; |
| } |
| |
| // Function that tries to get map from a pinned path. |
| base::Result<void> init(const char* path); |
| |
| // Iterate through the map and handle each key retrieved based on the filter |
| // without modification of map content. |
| base::Result<void> iterate( |
| const std::function<base::Result<void>(const Key& key, const BpfMap<Key, Value>& map)>& |
| filter) const; |
| |
| // Iterate through the map and get each <key, value> pair, handle each <key, |
| // value> pair based on the filter without modification of map content. |
| base::Result<void> iterateWithValue( |
| const std::function<base::Result<void>(const Key& key, const Value& value, |
| const BpfMap<Key, Value>& map)>& filter) const; |
| |
| // Iterate through the map and handle each key retrieved based on the filter |
| base::Result<void> iterate( |
| const std::function<base::Result<void>(const Key& key, BpfMap<Key, Value>& map)>& |
| filter); |
| |
| // Iterate through the map and get each <key, value> pair, handle each <key, |
| // value> pair based on the filter. |
| base::Result<void> iterateWithValue( |
| const std::function<base::Result<void>(const Key& key, const Value& value, |
| BpfMap<Key, Value>& map)>& filter); |
| |
| const base::unique_fd& getMap() const { return mMapFd; }; |
| |
| // Copy assignment operator |
| BpfMap<Key, Value>& operator=(const BpfMap<Key, Value>& other) { |
| if (this != &other) mMapFd.reset(fcntl(other.mMapFd.get(), F_DUPFD_CLOEXEC, 0)); |
| return *this; |
| } |
| |
| // Move constructor |
| void operator=(BpfMap<Key, Value>&& other) noexcept { |
| mMapFd = std::move(other.mMapFd); |
| other.reset(-1); |
| } |
| |
| void reset(base::unique_fd fd) = delete; |
| |
| void reset(int fd) { mMapFd.reset(fd); } |
| |
| bool isValid() const { return mMapFd != -1; } |
| |
| base::Result<void> clear() { |
| while (true) { |
| auto key = getFirstKey(); |
| if (!key.ok()) { |
| if (key.error().code() == ENOENT) return {}; // empty: success |
| return key.error(); // Anything else is an error |
| } |
| auto res = deleteValue(key.value()); |
| if (!res.ok()) { |
| // Someone else could have deleted the key, so ignore ENOENT |
| if (res.error().code() == ENOENT) continue; |
| ALOGE("Failed to delete data %s", strerror(res.error().code())); |
| return res.error(); |
| } |
| } |
| } |
| |
| base::Result<bool> isEmpty() const { |
| auto key = getFirstKey(); |
| if (!key.ok()) { |
| // Return error code ENOENT means the map is empty |
| if (key.error().code() == ENOENT) return true; |
| return key.error(); |
| } |
| return false; |
| } |
| |
| private: |
| base::unique_fd mMapFd; |
| }; |
| |
| template <class Key, class Value> |
| base::Result<void> BpfMap<Key, Value>::init(const char* path) { |
| mMapFd = base::unique_fd(mapRetrieve(path, 0)); |
| if (mMapFd == -1) { |
| return ErrnoErrorf("Pinned map not accessible or does not exist: ({})", path); |
| } |
| return {}; |
| } |
| |
| template <class Key, class Value> |
| base::Result<void> BpfMap<Key, Value>::iterate( |
| const std::function<base::Result<void>(const Key& key, const BpfMap<Key, Value>& map)>& |
| filter) const { |
| base::Result<Key> curKey = getFirstKey(); |
| while (curKey.ok()) { |
| const base::Result<Key>& nextKey = getNextKey(curKey.value()); |
| base::Result<void> status = filter(curKey.value(), *this); |
| if (!status.ok()) return status; |
| curKey = nextKey; |
| } |
| if (curKey.error().code() == ENOENT) return {}; |
| return curKey.error(); |
| } |
| |
| template <class Key, class Value> |
| base::Result<void> BpfMap<Key, Value>::iterateWithValue( |
| const std::function<base::Result<void>(const Key& key, const Value& value, |
| const BpfMap<Key, Value>& map)>& filter) const { |
| base::Result<Key> curKey = getFirstKey(); |
| while (curKey.ok()) { |
| const base::Result<Key>& nextKey = getNextKey(curKey.value()); |
| base::Result<Value> curValue = readValue(curKey.value()); |
| if (!curValue.ok()) return curValue.error(); |
| base::Result<void> status = filter(curKey.value(), curValue.value(), *this); |
| if (!status.ok()) return status; |
| curKey = nextKey; |
| } |
| if (curKey.error().code() == ENOENT) return {}; |
| return curKey.error(); |
| } |
| |
| template <class Key, class Value> |
| base::Result<void> BpfMap<Key, Value>::iterate( |
| const std::function<base::Result<void>(const Key& key, BpfMap<Key, Value>& map)>& filter) { |
| base::Result<Key> curKey = getFirstKey(); |
| while (curKey.ok()) { |
| const base::Result<Key>& nextKey = getNextKey(curKey.value()); |
| base::Result<void> status = filter(curKey.value(), *this); |
| if (!status.ok()) return status; |
| curKey = nextKey; |
| } |
| if (curKey.error().code() == ENOENT) return {}; |
| return curKey.error(); |
| } |
| |
| template <class Key, class Value> |
| base::Result<void> BpfMap<Key, Value>::iterateWithValue( |
| const std::function<base::Result<void>(const Key& key, const Value& value, |
| BpfMap<Key, Value>& map)>& filter) { |
| base::Result<Key> curKey = getFirstKey(); |
| while (curKey.ok()) { |
| const base::Result<Key>& nextKey = getNextKey(curKey.value()); |
| base::Result<Value> curValue = readValue(curKey.value()); |
| if (!curValue.ok()) return curValue.error(); |
| base::Result<void> status = filter(curKey.value(), curValue.value(), *this); |
| if (!status.ok()) return status; |
| curKey = nextKey; |
| } |
| if (curKey.error().code() == ENOENT) return {}; |
| return curKey.error(); |
| } |
| |
| template <class Key, class Value> |
| class BpfMapRO : public BpfMap<Key, Value> { |
| public: |
| explicit BpfMapRO<Key, Value>(const char* pathname) |
| : BpfMap<Key, Value>(pathname, BPF_F_RDONLY) {} |
| }; |
| |
| } // namespace bpf |
| } // namespace android |
| |
| #endif |