| /* |
| * Copyright (C) 2017 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. |
| */ |
| |
| #pragma once |
| |
| #include <functional> |
| #include <linux/netlink.h> |
| #include <linux/rtnetlink.h> |
| |
| #include "NetdConstants.h" |
| |
| namespace android::net { |
| |
| const sockaddr_nl KERNEL_NLADDR = {AF_NETLINK, 0, 0, 0}; |
| |
| const uint16_t NETLINK_REQUEST_FLAGS = NLM_F_REQUEST | NLM_F_ACK; |
| const uint16_t NETLINK_ROUTE_CREATE_FLAGS = NETLINK_REQUEST_FLAGS | NLM_F_CREATE | NLM_F_EXCL; |
| const uint16_t NETLINK_ROUTE_REPLACE_FLAGS = NETLINK_REQUEST_FLAGS | NLM_F_REPLACE; |
| // Don't create rules with NLM_F_EXCL, because operations such as changing network permissions rely |
| // on make-before-break. The kernel did not complain about duplicate rules until ~4.9, at which |
| // point it started returning EEXIST. See for example b/69607866 . We can't just ignore the EEXIST |
| // because if we hit it, the rule was not created, but we will think it was, and we'll then trip up |
| // trying to delete it. |
| const uint16_t NETLINK_RULE_CREATE_FLAGS = NETLINK_REQUEST_FLAGS | NLM_F_CREATE; |
| const uint16_t NETLINK_DUMP_FLAGS = NLM_F_REQUEST | NLM_F_DUMP; |
| |
| // Generic code for processing netlink dumps. |
| const int kNetlinkDumpBufferSize = 8192; |
| typedef std::function<void(nlmsghdr *)> NetlinkDumpCallback; |
| typedef std::function<bool(nlmsghdr *)> NetlinkDumpFilter; |
| |
| // Opens an RTNetlink socket and connects it to the kernel. |
| [[nodiscard]] int openNetlinkSocket(int protocol); |
| |
| // Receives a netlink ACK. Returns 0 if the command succeeded or negative errno if the command |
| // failed or receiving the ACK failed. |
| [[nodiscard]] int recvNetlinkAck(int sock); |
| |
| // Sends a netlink request and possibly expects an ACK. The first element of iov should be null and |
| // will be set to the netlink message headerheader. The subsequent elements are the contents of the |
| // request. |
| [[nodiscard]] int sendNetlinkRequest(uint16_t action, uint16_t flags, iovec* iov, int iovlen, |
| const NetlinkDumpCallback* callback); |
| |
| // Processes a netlink dump, passing every message to the specified |callback|. |
| [[nodiscard]] int processNetlinkDump(int sock, const NetlinkDumpCallback& callback); |
| |
| // Flushes netlink objects that take an rtmsg structure (FIB rules, routes...). |getAction| and |
| // |deleteAction| specify the netlink message types, e.g., RTM_GETRULE and RTM_DELRULE. |
| // |shouldDelete| specifies whether a given object should be deleted or not. |what| is a |
| // human-readable name for the objects being flushed, e.g. "rules". |
| [[nodiscard]] int rtNetlinkFlush(uint16_t getAction, uint16_t deleteAction, const char* what, |
| const NetlinkDumpFilter& shouldDelete); |
| |
| // Returns the value of the specific __u32 attribute, or 0 if the attribute was not present. |
| uint32_t getRtmU32Attribute(const nlmsghdr *nlh, int attribute); |
| |
| } // namespace android::net |