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Chenbo Feng75b410b2018-10-10 15:01:19 -07001/*
2 * Copyright (C) 2018 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef BPF_BPFMAP_H
18#define BPF_BPFMAP_H
19
20#include <linux/bpf.h>
21
Steven Morelande7cd2a72020-01-10 17:49:35 -080022#include <android-base/result.h>
Chenbo Feng75b410b2018-10-10 15:01:19 -070023#include <android-base/stringprintf.h>
24#include <android-base/unique_fd.h>
25#include <utils/Log.h>
26#include "bpf/BpfUtils.h"
Chenbo Feng75b410b2018-10-10 15:01:19 -070027
28namespace android {
29namespace bpf {
30
31// This is a class wrapper for eBPF maps. The eBPF map is a special in-kernel
32// data structure that stores data in <Key, Value> pairs. It can be read/write
33// from userspace by passing syscalls with the map file descriptor. This class
34// is used to generalize the procedure of interacting with eBPF maps and hide
35// the implementation detail from other process. Besides the basic syscalls
36// wrapper, it also provides some useful helper functions as well as an iterator
37// nested class to iterate the map more easily.
38//
39// NOTE: A kernel eBPF map may be accessed by both kernel and userspace
40// processes at the same time. Or if the map is pinned as a virtual file, it can
41// be obtained by multiple eBPF map class object and accessed concurrently.
42// Though the map class object and the underlying kernel map are thread safe, it
43// is not safe to iterate over a map while another thread or process is deleting
44// from it. In this case the iteration can return duplicate entries.
45template <class Key, class Value>
46class BpfMap {
47 public:
Maciej Żenczykowskie6cbd402019-08-09 18:20:26 -070048 BpfMap<Key, Value>() {};
Maciej Żenczykowskie6cbd402019-08-09 18:20:26 -070049
Maciej Żenczykowskidfd941f2020-01-20 03:18:26 -080050 protected:
51 // flag must be within BPF_OBJ_FLAG_MASK, ie. 0, BPF_F_RDONLY, BPF_F_WRONLY
52 BpfMap<Key, Value>(const char* pathname, uint32_t flags) {
53 int map_fd = mapRetrieve(pathname, flags);
54 if (map_fd >= 0) mMapFd.reset(map_fd);
55 }
56
57 public:
58 explicit BpfMap<Key, Value>(const char* pathname) : BpfMap<Key, Value>(pathname, 0) {}
Maciej Żenczykowskie6cbd402019-08-09 18:20:26 -070059
Hungming Chen6161ff22020-03-05 14:47:53 +080060 BpfMap<Key, Value>(bpf_map_type map_type, uint32_t max_entries, uint32_t map_flags = 0) {
Chenbo Feng75b410b2018-10-10 15:01:19 -070061 int map_fd = createMap(map_type, sizeof(Key), sizeof(Value), max_entries, map_flags);
Maciej Żenczykowskidfd941f2020-01-20 03:18:26 -080062 if (map_fd >= 0) mMapFd.reset(map_fd);
Chenbo Feng75b410b2018-10-10 15:01:19 -070063 }
64
Steven Morelande7cd2a72020-01-10 17:49:35 -080065 base::Result<Key> getFirstKey() const {
Chenbo Feng75b410b2018-10-10 15:01:19 -070066 Key firstKey;
67 if (getFirstMapKey(mMapFd, &firstKey)) {
Tom Cherrya7146db2020-02-04 15:27:30 -080068 return ErrnoErrorf("Get firstKey map {} failed", mMapFd.get());
Chenbo Feng75b410b2018-10-10 15:01:19 -070069 }
70 return firstKey;
71 }
72
Steven Morelande7cd2a72020-01-10 17:49:35 -080073 base::Result<Key> getNextKey(const Key& key) const {
Chenbo Feng75b410b2018-10-10 15:01:19 -070074 Key nextKey;
Maciej Żenczykowski79365da2020-01-17 19:07:37 -080075 if (getNextMapKey(mMapFd, &key, &nextKey)) {
Tom Cherrya7146db2020-02-04 15:27:30 -080076 return ErrnoErrorf("Get next key of map {} failed", mMapFd.get());
Chenbo Feng75b410b2018-10-10 15:01:19 -070077 }
78 return nextKey;
79 }
80
Steven Morelande7cd2a72020-01-10 17:49:35 -080081 base::Result<void> writeValue(const Key& key, const Value& value, uint64_t flags) {
Maciej Żenczykowski79365da2020-01-17 19:07:37 -080082 if (writeToMapEntry(mMapFd, &key, &value, flags)) {
Tom Cherrya7146db2020-02-04 15:27:30 -080083 return ErrnoErrorf("Write to map {} failed", mMapFd.get());
Chenbo Feng75b410b2018-10-10 15:01:19 -070084 }
Steven Morelande7cd2a72020-01-10 17:49:35 -080085 return {};
Chenbo Feng75b410b2018-10-10 15:01:19 -070086 }
87
Steven Morelande7cd2a72020-01-10 17:49:35 -080088 base::Result<Value> readValue(const Key key) const {
Chenbo Feng75b410b2018-10-10 15:01:19 -070089 Value value;
Maciej Żenczykowski79365da2020-01-17 19:07:37 -080090 if (findMapEntry(mMapFd, &key, &value)) {
Tom Cherrya7146db2020-02-04 15:27:30 -080091 return ErrnoErrorf("Read value of map {} failed", mMapFd.get());
Chenbo Feng75b410b2018-10-10 15:01:19 -070092 }
93 return value;
94 }
95
Steven Morelande7cd2a72020-01-10 17:49:35 -080096 base::Result<void> deleteValue(const Key& key) {
Maciej Żenczykowski79365da2020-01-17 19:07:37 -080097 if (deleteMapEntry(mMapFd, &key)) {
Tom Cherrya7146db2020-02-04 15:27:30 -080098 return ErrnoErrorf("Delete entry from map {} failed", mMapFd.get());
Chenbo Feng75b410b2018-10-10 15:01:19 -070099 }
Steven Morelande7cd2a72020-01-10 17:49:35 -0800100 return {};
Chenbo Feng75b410b2018-10-10 15:01:19 -0700101 }
102
Maciej Żenczykowski52108bf2019-04-01 10:41:13 -0700103 // Function that tries to get map from a pinned path.
Steven Morelande7cd2a72020-01-10 17:49:35 -0800104 base::Result<void> init(const char* path);
Chenbo Feng75b410b2018-10-10 15:01:19 -0700105
106 // Iterate through the map and handle each key retrieved based on the filter
107 // without modification of map content.
Steven Morelande7cd2a72020-01-10 17:49:35 -0800108 base::Result<void> iterate(
109 const std::function<base::Result<void>(const Key& key, const BpfMap<Key, Value>& map)>&
110 filter) const;
Chenbo Feng75b410b2018-10-10 15:01:19 -0700111
112 // Iterate through the map and get each <key, value> pair, handle each <key,
113 // value> pair based on the filter without modification of map content.
Steven Morelande7cd2a72020-01-10 17:49:35 -0800114 base::Result<void> iterateWithValue(
115 const std::function<base::Result<void>(const Key& key, const Value& value,
116 const BpfMap<Key, Value>& map)>& filter) const;
Chenbo Feng75b410b2018-10-10 15:01:19 -0700117
118 // Iterate through the map and handle each key retrieved based on the filter
Steven Morelande7cd2a72020-01-10 17:49:35 -0800119 base::Result<void> iterate(
120 const std::function<base::Result<void>(const Key& key, BpfMap<Key, Value>& map)>&
121 filter);
Chenbo Feng75b410b2018-10-10 15:01:19 -0700122
123 // Iterate through the map and get each <key, value> pair, handle each <key,
124 // value> pair based on the filter.
Steven Morelande7cd2a72020-01-10 17:49:35 -0800125 base::Result<void> iterateWithValue(
126 const std::function<base::Result<void>(const Key& key, const Value& value,
127 BpfMap<Key, Value>& map)>& filter);
Chenbo Feng75b410b2018-10-10 15:01:19 -0700128
129 const base::unique_fd& getMap() const { return mMapFd; };
130
Hungming Chen4008da92020-02-27 17:26:40 +0800131 // Copy assignment operator
132 void operator=(const BpfMap<Key, Value>& other) {
133 mMapFd.reset(fcntl(other.mMapFd.get(), F_DUPFD_CLOEXEC, 0));
134 }
135
Chenbo Feng75b410b2018-10-10 15:01:19 -0700136 // Move constructor
137 void operator=(BpfMap<Key, Value>&& other) noexcept {
138 mMapFd = std::move(other.mMapFd);
Maciej Żenczykowski4f657392020-01-20 15:06:22 -0800139 other.reset(-1);
Chenbo Feng75b410b2018-10-10 15:01:19 -0700140 }
141
Maciej Żenczykowski4f657392020-01-20 15:06:22 -0800142 void reset(base::unique_fd fd) = delete;
143
144 void reset(int fd) { mMapFd.reset(fd); }
Chenbo Feng75b410b2018-10-10 15:01:19 -0700145
146 bool isValid() const { return mMapFd != -1; }
147
Steven Morelande7cd2a72020-01-10 17:49:35 -0800148 base::Result<void> clear() {
Maciej Żenczykowskib7176fb2020-02-19 10:59:09 -0800149 while (true) {
150 auto key = getFirstKey();
151 if (!key.ok()) {
152 if (key.error().code() == ENOENT) return {}; // empty: success
153 return key.error(); // Anything else is an error
Chenbo Feng75b410b2018-10-10 15:01:19 -0700154 }
Maciej Żenczykowskib7176fb2020-02-19 10:59:09 -0800155 auto res = deleteValue(key.value());
156 if (!res.ok()) {
157 // Someone else could have deleted the key, so ignore ENOENT
158 if (res.error().code() == ENOENT) continue;
159 ALOGE("Failed to delete data %s", strerror(res.error().code()));
160 return res.error();
161 }
162 }
Chenbo Feng75b410b2018-10-10 15:01:19 -0700163 }
164
Steven Morelande7cd2a72020-01-10 17:49:35 -0800165 base::Result<bool> isEmpty() const {
Maciej Żenczykowskib7176fb2020-02-19 10:59:09 -0800166 auto key = getFirstKey();
Bernie Innocenti43d25382020-02-10 07:25:16 +0900167 if (!key.ok()) {
Steven Morelande7cd2a72020-01-10 17:49:35 -0800168 // Return error code ENOENT means the map is empty
169 if (key.error().code() == ENOENT) return true;
170 return key.error();
171 }
Chenbo Feng75b410b2018-10-10 15:01:19 -0700172 return false;
173 }
174
175 private:
176 base::unique_fd mMapFd;
Chenbo Feng75b410b2018-10-10 15:01:19 -0700177};
178
179template <class Key, class Value>
Steven Morelande7cd2a72020-01-10 17:49:35 -0800180base::Result<void> BpfMap<Key, Value>::init(const char* path) {
Maciej Żenczykowski52108bf2019-04-01 10:41:13 -0700181 mMapFd = base::unique_fd(mapRetrieve(path, 0));
182 if (mMapFd == -1) {
Tom Cherrya7146db2020-02-04 15:27:30 -0800183 return ErrnoErrorf("Pinned map not accessible or does not exist: ({})", path);
Chenbo Feng75b410b2018-10-10 15:01:19 -0700184 }
Steven Morelande7cd2a72020-01-10 17:49:35 -0800185 return {};
Chenbo Feng75b410b2018-10-10 15:01:19 -0700186}
187
188template <class Key, class Value>
Steven Morelande7cd2a72020-01-10 17:49:35 -0800189base::Result<void> BpfMap<Key, Value>::iterate(
190 const std::function<base::Result<void>(const Key& key, const BpfMap<Key, Value>& map)>&
191 filter) const {
192 base::Result<Key> curKey = getFirstKey();
Bernie Innocenti5953dee2020-02-06 04:22:41 +0900193 while (curKey.ok()) {
Steven Morelande7cd2a72020-01-10 17:49:35 -0800194 const base::Result<Key>& nextKey = getNextKey(curKey.value());
195 base::Result<void> status = filter(curKey.value(), *this);
Bernie Innocenti5953dee2020-02-06 04:22:41 +0900196 if (!status.ok()) return status;
Chenbo Feng75b410b2018-10-10 15:01:19 -0700197 curKey = nextKey;
198 }
Steven Morelande7cd2a72020-01-10 17:49:35 -0800199 if (curKey.error().code() == ENOENT) return {};
200 return curKey.error();
Chenbo Feng75b410b2018-10-10 15:01:19 -0700201}
202
203template <class Key, class Value>
Steven Morelande7cd2a72020-01-10 17:49:35 -0800204base::Result<void> BpfMap<Key, Value>::iterateWithValue(
205 const std::function<base::Result<void>(const Key& key, const Value& value,
206 const BpfMap<Key, Value>& map)>& filter) const {
207 base::Result<Key> curKey = getFirstKey();
Bernie Innocenti5953dee2020-02-06 04:22:41 +0900208 while (curKey.ok()) {
Steven Morelande7cd2a72020-01-10 17:49:35 -0800209 const base::Result<Key>& nextKey = getNextKey(curKey.value());
Maciej Żenczykowskib7176fb2020-02-19 10:59:09 -0800210 base::Result<Value> curValue = readValue(curKey.value());
Bernie Innocenti5953dee2020-02-06 04:22:41 +0900211 if (!curValue.ok()) return curValue.error();
Steven Morelande7cd2a72020-01-10 17:49:35 -0800212 base::Result<void> status = filter(curKey.value(), curValue.value(), *this);
Bernie Innocenti5953dee2020-02-06 04:22:41 +0900213 if (!status.ok()) return status;
Chenbo Feng75b410b2018-10-10 15:01:19 -0700214 curKey = nextKey;
215 }
Steven Morelande7cd2a72020-01-10 17:49:35 -0800216 if (curKey.error().code() == ENOENT) return {};
217 return curKey.error();
Chenbo Feng75b410b2018-10-10 15:01:19 -0700218}
219
220template <class Key, class Value>
Steven Morelande7cd2a72020-01-10 17:49:35 -0800221base::Result<void> BpfMap<Key, Value>::iterate(
222 const std::function<base::Result<void>(const Key& key, BpfMap<Key, Value>& map)>& filter) {
223 base::Result<Key> curKey = getFirstKey();
Bernie Innocenti5953dee2020-02-06 04:22:41 +0900224 while (curKey.ok()) {
Steven Morelande7cd2a72020-01-10 17:49:35 -0800225 const base::Result<Key>& nextKey = getNextKey(curKey.value());
226 base::Result<void> status = filter(curKey.value(), *this);
Bernie Innocenti5953dee2020-02-06 04:22:41 +0900227 if (!status.ok()) return status;
Chenbo Feng75b410b2018-10-10 15:01:19 -0700228 curKey = nextKey;
229 }
Steven Morelande7cd2a72020-01-10 17:49:35 -0800230 if (curKey.error().code() == ENOENT) return {};
231 return curKey.error();
Chenbo Feng75b410b2018-10-10 15:01:19 -0700232}
233
234template <class Key, class Value>
Steven Morelande7cd2a72020-01-10 17:49:35 -0800235base::Result<void> BpfMap<Key, Value>::iterateWithValue(
236 const std::function<base::Result<void>(const Key& key, const Value& value,
237 BpfMap<Key, Value>& map)>& filter) {
238 base::Result<Key> curKey = getFirstKey();
Bernie Innocenti5953dee2020-02-06 04:22:41 +0900239 while (curKey.ok()) {
Steven Morelande7cd2a72020-01-10 17:49:35 -0800240 const base::Result<Key>& nextKey = getNextKey(curKey.value());
Maciej Żenczykowskib7176fb2020-02-19 10:59:09 -0800241 base::Result<Value> curValue = readValue(curKey.value());
Bernie Innocenti5953dee2020-02-06 04:22:41 +0900242 if (!curValue.ok()) return curValue.error();
Steven Morelande7cd2a72020-01-10 17:49:35 -0800243 base::Result<void> status = filter(curKey.value(), curValue.value(), *this);
Bernie Innocenti5953dee2020-02-06 04:22:41 +0900244 if (!status.ok()) return status;
Chenbo Feng75b410b2018-10-10 15:01:19 -0700245 curKey = nextKey;
246 }
Steven Morelande7cd2a72020-01-10 17:49:35 -0800247 if (curKey.error().code() == ENOENT) return {};
248 return curKey.error();
Chenbo Feng75b410b2018-10-10 15:01:19 -0700249}
250
Maciej Żenczykowskidfd941f2020-01-20 03:18:26 -0800251template <class Key, class Value>
252class BpfMapRO : public BpfMap<Key, Value> {
253 public:
254 explicit BpfMapRO<Key, Value>(const char* pathname)
255 : BpfMap<Key, Value>(pathname, BPF_F_RDONLY) {}
256};
257
Chenbo Feng75b410b2018-10-10 15:01:19 -0700258} // namespace bpf
259} // namespace android
260
261#endif