1 /* 2 * Copyright (C) 2017 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 NETD_SERVER_NETLINK_UTIL_H 18 #define NETD_SERVER_NETLINK_UTIL_H 19 20 #include <functional> 21 #include <linux/netlink.h> 22 #include <linux/rtnetlink.h> 23 24 #include "NetdConstants.h" 25 26 namespace android { 27 namespace net { 28 29 const sockaddr_nl KERNEL_NLADDR = {AF_NETLINK, 0, 0, 0}; 30 31 const uint16_t NETLINK_REQUEST_FLAGS = NLM_F_REQUEST | NLM_F_ACK; 32 const uint16_t NETLINK_CREATE_REQUEST_FLAGS = NETLINK_REQUEST_FLAGS | NLM_F_CREATE | NLM_F_EXCL; 33 const uint16_t NETLINK_DUMP_FLAGS = NLM_F_REQUEST | NLM_F_DUMP; 34 35 // Generic code for processing netlink dumps. 36 const int kNetlinkDumpBufferSize = 8192; 37 typedef std::function<void(nlmsghdr *)> NetlinkDumpCallback; 38 typedef std::function<bool(nlmsghdr *)> NetlinkDumpFilter; 39 40 // Opens an RTNetlink socket and connects it to the kernel. 41 WARN_UNUSED_RESULT int openNetlinkSocket(int protocol); 42 43 // Receives a netlink ACK. Returns 0 if the command succeeded or negative errno if the command 44 // failed or receiving the ACK failed. 45 WARN_UNUSED_RESULT int recvNetlinkAck(int sock); 46 47 // Sends a netlink request and possibly expects an ACK. The first element of iov should be null and 48 // will be set to the netlink message headerheader. The subsequent elements are the contents of the 49 // request. 50 51 // Disable optimizations in ASan build. 52 // ASan reports an out-of-bounds 32-bit(!) access in the first loop of the 53 // function (over iov[]). 54 #ifdef __clang__ 55 #if __has_feature(address_sanitizer) 56 __attribute__((optnone)) 57 #endif 58 #endif 59 WARN_UNUSED_RESULT int sendNetlinkRequest(uint16_t action, uint16_t flags, iovec* iov, int iovlen, 60 const NetlinkDumpCallback *callback); 61 62 // Processes a netlink dump, passing every message to the specified |callback|. 63 WARN_UNUSED_RESULT int processNetlinkDump(int sock, const NetlinkDumpCallback& callback); 64 65 // Flushes netlink objects that take an rtmsg structure (FIB rules, routes...). |getAction| and 66 // |deleteAction| specify the netlink message types, e.g., RTM_GETRULE and RTM_DELRULE. 67 // |shouldDelete| specifies whether a given object should be deleted or not. |what| is a 68 // human-readable name for the objects being flushed, e.g. "rules". 69 WARN_UNUSED_RESULT int rtNetlinkFlush(uint16_t getAction, uint16_t deleteAction, 70 const char *what, const NetlinkDumpFilter& shouldDelete); 71 72 // Returns the value of the specific __u32 attribute, or 0 if the attribute was not present. 73 uint32_t getRtmU32Attribute(const nlmsghdr *nlh, int attribute); 74 75 } // namespace net 76 } // namespace android 77 78 #endif // NETD_SERVER_NETLINK_UTIL_H 79