/*
* 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/stringprintf.h>
#include <android-base/unique_fd.h>
#include <utils/Log.h>
#include "bpf/BpfUtils.h"
#include "netdutils/Status.h"
#include "netdutils/StatusOr.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 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:
class const_iterator {
public:
netdutils::Status start() {
if (mMap == nullptr) {
return netdutils::statusFromErrno(EINVAL, "Invalid map iterator");
}
auto firstKey = mMap->getFirstKey();
if (isOk(firstKey)) {
mCurKey = firstKey.value();
} else if (firstKey.status().code() == ENOENT) {
// The map is empty.
mMap = nullptr;
memset(&mCurKey, 0, sizeof(Key));
} else {
return firstKey.status();
}
return netdutils::status::ok;
}
netdutils::StatusOr<Key> next() {
if (mMap == nullptr) {
return netdutils::statusFromErrno(ENOENT, "Iterating past end of map");
}
auto nextKey = mMap->getNextKey(mCurKey);
if (isOk(nextKey)) {
mCurKey = nextKey.value();
} else if (nextKey.status().code() == ENOENT) {
// iterator reached the end of map
mMap = nullptr;
memset(&mCurKey, 0, sizeof(Key));
} else {
return nextKey.status();
}
return mCurKey;
}
const Key operator*() { return mCurKey; }
bool operator==(const const_iterator& other) const {
return (mMap == other.mMap) && (mCurKey == other.mCurKey);
}
bool operator!=(const const_iterator& other) const { return !(*this == other); }
const_iterator(const BpfMap<Key, Value>* map) : mMap(map) {
memset(&mCurKey, 0, sizeof(Key));
}
private:
const BpfMap<Key, Value> * mMap;
Key mCurKey;
};
BpfMap<Key, Value>() : mMapFd(-1){};
BpfMap<Key, Value>(int fd) : mMapFd(fd){};
BpfMap<Key, Value>(bpf_map_type map_type, uint32_t max_entries, uint32_t map_flags) {
int map_fd = createMap(map_type, sizeof(Key), sizeof(Value), max_entries, map_flags);
if (map_fd < 0) {
mMapFd.reset(-1);
} else {
mMapFd.reset(map_fd);
}
}
netdutils::Status pinToPath(const std::string path) {
int ret = mapPin(mMapFd, path.c_str());
if (ret) {
return netdutils::statusFromErrno(errno,
base::StringPrintf("pin to %s failed", path.c_str()));
}
mPinnedPath = path;
return netdutils::status::ok;
}
netdutils::StatusOr<Key> getFirstKey() const {
Key firstKey;
if (getFirstMapKey(mMapFd, &firstKey)) {
return netdutils::statusFromErrno(
errno, base::StringPrintf("Get firstKey map %d failed", mMapFd.get()));
}
return firstKey;
}
netdutils::StatusOr<Key> getNextKey(const Key& key) const {
Key nextKey;
if (getNextMapKey(mMapFd, const_cast<Key*>(&key), &nextKey)) {
return netdutils::statusFromErrno(
errno, base::StringPrintf("Get next key of map %d failed", mMapFd.get()));
}
return nextKey;
}
netdutils::Status writeValue(const Key& key, const Value& value, uint64_t flags) {
if (writeToMapEntry(mMapFd, const_cast<Key*>(&key), const_cast<Value*>(&value), flags)) {
return netdutils::statusFromErrno(
errno, base::StringPrintf("write to map %d failed", mMapFd.get()));
}
return netdutils::status::ok;
}
netdutils::StatusOr<Value> readValue(const Key key) const {
Value value;
if (findMapEntry(mMapFd, const_cast<Key*>(&key), &value)) {
return netdutils::statusFromErrno(
errno, base::StringPrintf("read value of map %d failed", mMapFd.get()));
}
return value;
}
netdutils::Status deleteValue(const Key& key) {
if (deleteMapEntry(mMapFd, const_cast<Key*>(&key))) {
return netdutils::statusFromErrno(
errno, base::StringPrintf("delete entry from map %d failed", mMapFd.get()));
}
return netdutils::status::ok;
}
// Function that tries to get map from a pinned path, if the map doesn't
// exist yet, create a new one and pinned to the path.
netdutils::Status getOrCreate(const uint32_t maxEntries, const char* path,
const bpf_map_type mapType);
// Iterate through the map and handle each key retrieved based on the filter
// without modification of map content.
netdutils::Status iterate(
const std::function<netdutils::Status(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.
netdutils::Status iterateWithValue(
const std::function<netdutils::Status(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
netdutils::Status iterate(
const std::function<netdutils::Status(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.
netdutils::Status iterateWithValue(
const std::function<netdutils::Status(const Key& key, const Value& value,
BpfMap<Key, Value>& map)>& filter);
const base::unique_fd& getMap() const { return mMapFd; };
const std::string getPinnedPath() const { return mPinnedPath; };
// Move constructor
void operator=(BpfMap<Key, Value>&& other) {
mMapFd = std::move(other.mMapFd);
if (!other.mPinnedPath.empty()) {
mPinnedPath = other.mPinnedPath;
} else {
mPinnedPath.clear();
}
other.reset();
}
void reset(int fd = -1) {
mMapFd.reset(fd);
mPinnedPath.clear();
}
bool isValid() const { return mMapFd != -1; }
const_iterator begin() const { return const_iterator(this); }
const_iterator end() const { return const_iterator(nullptr); }
private:
base::unique_fd mMapFd;
std::string mPinnedPath;
};
template <class Key, class Value>
netdutils::Status BpfMap<Key, Value>::getOrCreate(const uint32_t maxEntries, const char* path,
bpf_map_type mapType) {
int ret = access(path, R_OK);
/* Check the pinned location first to check if the map is already there.
* otherwise create a new one.
*/
if (ret == 0) {
mMapFd = base::unique_fd(mapRetrieve(path, 0));
if (mMapFd == -1) {
reset();
return netdutils::statusFromErrno(
errno,
base::StringPrintf("pinned map not accessible or does not exist: (%s)\n", path));
}
mPinnedPath = path;
} else if (ret == -1 && errno == ENOENT) {
mMapFd = base::unique_fd(
createMap(mapType, sizeof(Key), sizeof(Value), maxEntries, BPF_F_NO_PREALLOC));
if (mMapFd == -1) {
reset();
return netdutils::statusFromErrno(errno,
base::StringPrintf("map create failed!: %s", path));
}
netdutils::Status pinStatus = pinToPath(path);
if (!isOk(pinStatus)) {
reset();
return pinStatus;
}
mPinnedPath = path;
} else {
return netdutils::statusFromErrno(
errno, base::StringPrintf("pinned map not accessible: %s", path));
}
return netdutils::status::ok;
}
template <class Key, class Value>
netdutils::Status BpfMap<Key, Value>::iterate(
const std::function<netdutils::Status(const Key& key, const BpfMap<Key, Value>& map)>& filter)
const {
const_iterator itr = this->begin();
RETURN_IF_NOT_OK(itr.start());
while (itr != this->end()) {
Key prevKey = *itr;
netdutils::Status advanceStatus = itr.next();
RETURN_IF_NOT_OK(filter(prevKey, *this));
RETURN_IF_NOT_OK(advanceStatus);
}
return netdutils::status::ok;
}
template <class Key, class Value>
netdutils::Status BpfMap<Key, Value>::iterateWithValue(
const std::function<netdutils::Status(const Key& key, const Value& value,
const BpfMap<Key, Value>& map)>& filter) const {
const_iterator itr = this->begin();
RETURN_IF_NOT_OK(itr.start());
while (itr != this->end()) {
Key prevKey = *itr;
Value prevValue;
ASSIGN_OR_RETURN(prevValue, this->readValue(prevKey));
netdutils::Status advanceStatus = itr.next();
RETURN_IF_NOT_OK(filter(prevKey, prevValue, *this));
RETURN_IF_NOT_OK(advanceStatus);
}
return netdutils::status::ok;
}
template <class Key, class Value>
netdutils::Status BpfMap<Key, Value>::iterate(
const std::function<netdutils::Status(const Key& key, BpfMap<Key, Value>& map)>& filter) {
const_iterator itr = this->begin();
RETURN_IF_NOT_OK(itr.start());
while (itr != this->end()) {
Key prevKey = *itr;
netdutils::Status advanceStatus = itr.next();
RETURN_IF_NOT_OK(filter(prevKey, *this));
RETURN_IF_NOT_OK(advanceStatus);
}
return netdutils::status::ok;
}
template <class Key, class Value>
netdutils::Status BpfMap<Key, Value>::iterateWithValue(
const std::function<netdutils::Status(const Key& key, const Value& value,
BpfMap<Key, Value>& map)>& filter) {
const_iterator itr = this->begin();
RETURN_IF_NOT_OK(itr.start());
while (itr != this->end()) {
Key prevKey = *itr;
Value prevValue;
ASSIGN_OR_RETURN(prevValue, this->readValue(prevKey));
netdutils::Status advanceStatus = itr.next();
RETURN_IF_NOT_OK(filter(prevKey, prevValue, *this));
RETURN_IF_NOT_OK(advanceStatus);
}
return netdutils::status::ok;
}
} // namespace bpf
} // namespace android
#endif