/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef NETD_SERVER_NETLINK_UTIL_H
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#define NETD_SERVER_NETLINK_UTIL_H
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#include <functional>
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#include <linux/netlink.h>
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#include <linux/rtnetlink.h>
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#include "NetdConstants.h"
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namespace android {
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namespace net {
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const sockaddr_nl KERNEL_NLADDR = {AF_NETLINK, 0, 0, 0};
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const uint16_t NETLINK_REQUEST_FLAGS = NLM_F_REQUEST | NLM_F_ACK;
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const uint16_t NETLINK_ROUTE_CREATE_FLAGS = NETLINK_REQUEST_FLAGS | NLM_F_CREATE | NLM_F_EXCL;
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// Don't create rules with NLM_F_EXCL, because operations such as changing network permissions rely
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// on make-before-break. The kernel did not complain about duplicate rules until ~4.9, at which
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// point it started returning EEXIST. See for example b/69607866 . We can't just ignore the EEXIST
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// because if we hit it, the rule was not created, but we will think it was, and we'll then trip up
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// trying to delete it.
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const uint16_t NETLINK_RULE_CREATE_FLAGS = NETLINK_REQUEST_FLAGS | NLM_F_CREATE;
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const uint16_t NETLINK_DUMP_FLAGS = NLM_F_REQUEST | NLM_F_DUMP;
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// Generic code for processing netlink dumps.
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const int kNetlinkDumpBufferSize = 8192;
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typedef std::function<void(nlmsghdr *)> NetlinkDumpCallback;
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typedef std::function<bool(nlmsghdr *)> NetlinkDumpFilter;
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// Opens an RTNetlink socket and connects it to the kernel.
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WARN_UNUSED_RESULT int openNetlinkSocket(int protocol);
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// Receives a netlink ACK. Returns 0 if the command succeeded or negative errno if the command
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// failed or receiving the ACK failed.
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WARN_UNUSED_RESULT int recvNetlinkAck(int sock);
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// Sends a netlink request and possibly expects an ACK. The first element of iov should be null and
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// will be set to the netlink message headerheader. The subsequent elements are the contents of the
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// request.
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// Disable optimizations in ASan build.
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// ASan reports an out-of-bounds 32-bit(!) access in the first loop of the
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// function (over iov[]).
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#ifdef __clang__
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#if __has_feature(address_sanitizer)
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__attribute__((optnone))
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#endif
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#endif
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WARN_UNUSED_RESULT int sendNetlinkRequest(uint16_t action, uint16_t flags, iovec* iov, int iovlen,
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const NetlinkDumpCallback *callback);
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// Processes a netlink dump, passing every message to the specified |callback|.
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WARN_UNUSED_RESULT int processNetlinkDump(int sock, const NetlinkDumpCallback& callback);
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// Flushes netlink objects that take an rtmsg structure (FIB rules, routes...). |getAction| and
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// |deleteAction| specify the netlink message types, e.g., RTM_GETRULE and RTM_DELRULE.
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// |shouldDelete| specifies whether a given object should be deleted or not. |what| is a
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// human-readable name for the objects being flushed, e.g. "rules".
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WARN_UNUSED_RESULT int rtNetlinkFlush(uint16_t getAction, uint16_t deleteAction,
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const char *what, const NetlinkDumpFilter& shouldDelete);
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// Returns the value of the specific __u32 attribute, or 0 if the attribute was not present.
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uint32_t getRtmU32Attribute(const nlmsghdr *nlh, int attribute);
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} // namespace net
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} // namespace android
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#endif // NETD_SERVER_NETLINK_UTIL_H
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