/*
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* Copyright (C) 2019 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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#include "ClatUtils.h"
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#include <arpa/inet.h>
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#include <errno.h>
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#include <linux/if.h>
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#include <linux/netlink.h>
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#include <linux/pkt_cls.h>
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#include <linux/pkt_sched.h>
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#include <linux/rtnetlink.h>
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#include <sys/ioctl.h>
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#include <sys/socket.h>
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#include <sys/types.h>
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#include <unistd.h>
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#define LOG_TAG "ClatUtils"
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#include <log/log.h>
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#include "NetlinkCommands.h"
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#include "android-base/unique_fd.h"
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#include "bpf/BpfUtils.h"
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#include "netdbpf/bpf_shared.h"
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namespace android {
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namespace net {
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int hardwareAddressType(const std::string& interface) {
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base::unique_fd ufd(socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, 0));
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if (ufd < 0) {
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const int err = errno;
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ALOGE("socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, 0)");
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return -err;
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};
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struct ifreq ifr = {};
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// We use strncpy() instead of strlcpy() since kernel has to be able
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// to handle non-zero terminated junk passed in by userspace anyway,
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// and this way too long interface names (more than IFNAMSIZ-1 = 15
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// characters plus terminating NULL) will not get truncated to 15
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// characters and zero-terminated and thus potentially erroneously
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// match a truncated interface if one were to exist.
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strncpy(ifr.ifr_name, interface.c_str(), sizeof(ifr.ifr_name));
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if (ioctl(ufd, SIOCGIFHWADDR, &ifr, sizeof(ifr))) return -errno;
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return ifr.ifr_hwaddr.sa_family;
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}
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int getClatIngressMapFd(void) {
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const int fd = bpf::bpfFdGet(CLAT_INGRESS_MAP_PATH, 0);
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return (fd == -1) ? -errno : fd;
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}
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int getClatIngressProgFd(bool with_ethernet_header) {
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const int fd = bpf::bpfFdGet(
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with_ethernet_header ? CLAT_INGRESS_PROG_ETHER_PATH : CLAT_INGRESS_PROG_RAWIP_PATH, 0);
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return (fd == -1) ? -errno : fd;
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}
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// TODO: use //system/netd/server/NetlinkCommands.cpp:openNetlinkSocket(protocol)
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int openNetlinkSocket(void) {
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base::unique_fd fd(socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE));
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if (fd == -1) {
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const int err = errno;
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ALOGE("socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE)");
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return -err;
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}
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int rv;
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const int on = 1;
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rv = setsockopt(fd, SOL_NETLINK, NETLINK_CAP_ACK, &on, sizeof(on));
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if (rv) ALOGE("setsockopt(fd, SOL_NETLINK, NETLINK_CAP_ACK, %d)", on);
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// this is needed to get sane strace netlink parsing, it allocates the pid
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rv = bind(fd, (const struct sockaddr*)&KERNEL_NLADDR, sizeof(KERNEL_NLADDR));
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if (rv) {
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const int err = errno;
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ALOGE("bind(fd, {AF_NETLINK, 0, 0})");
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return -err;
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}
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// we do not want to receive messages from anyone besides the kernel
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rv = connect(fd, (const struct sockaddr*)&KERNEL_NLADDR, sizeof(KERNEL_NLADDR));
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if (rv) {
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const int err = errno;
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ALOGE("connect(fd, {AF_NETLINK, 0, 0})");
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return -err;
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}
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return fd.release();
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}
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// TODO: merge with //system/netd/server/SockDiag.cpp:checkError(fd)
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int processNetlinkResponse(int fd) {
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struct {
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nlmsghdr h;
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nlmsgerr e;
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char buf[256];
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} resp = {};
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const int rv = recv(fd, &resp, sizeof(resp), MSG_TRUNC);
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if (rv == -1) {
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const int err = errno;
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ALOGE("recv() failed");
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return -err;
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}
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if (rv < (int)NLMSG_SPACE(sizeof(struct nlmsgerr))) {
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ALOGE("recv() returned short packet: %d", rv);
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return -EMSGSIZE;
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}
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if (resp.h.nlmsg_len != (unsigned)rv) {
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ALOGE("recv() returned invalid header length: %d != %d", resp.h.nlmsg_len, rv);
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return -EBADMSG;
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}
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if (resp.h.nlmsg_type != NLMSG_ERROR) {
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ALOGE("recv() did not return NLMSG_ERROR message: %d", resp.h.nlmsg_type);
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return -EBADMSG;
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}
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return resp.e.error; // returns 0 on success
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}
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// ADD: nlMsgType=RTM_NEWQDISC nlMsgFlags=NLM_F_EXCL|NLM_F_CREATE
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// REPLACE: nlMsgType=RTM_NEWQDISC nlMsgFlags=NLM_F_CREATE|NLM_F_REPLACE
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// DEL: nlMsgType=RTM_DELQDISC nlMsgFlags=0
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int doTcQdiscClsact(int fd, int ifIndex, __u16 nlMsgType, __u16 nlMsgFlags) {
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// This is the name of the qdisc we are attaching.
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// Some hoop jumping to make this compile time constant with known size,
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// so that the structure declaration is well defined at compile time.
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#define CLSACT "clsact"
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static const char clsact[] = CLSACT;
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// sizeof() includes the terminating NULL
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#define ASCIIZ_LEN_CLSACT sizeof(clsact)
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const struct {
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nlmsghdr n;
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tcmsg t;
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struct {
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nlattr attr;
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char str[NLMSG_ALIGN(ASCIIZ_LEN_CLSACT)];
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} kind;
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} req = {
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.n =
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{
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.nlmsg_len = sizeof(req),
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.nlmsg_type = nlMsgType,
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.nlmsg_flags = static_cast<__u16>(NETLINK_REQUEST_FLAGS | nlMsgFlags),
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},
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.t =
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{
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.tcm_family = AF_UNSPEC,
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.tcm_ifindex = ifIndex,
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.tcm_handle = TC_H_MAKE(TC_H_CLSACT, 0),
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.tcm_parent = TC_H_CLSACT,
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},
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.kind =
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{
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.attr =
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{
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.nla_len = NLA_HDRLEN + ASCIIZ_LEN_CLSACT,
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.nla_type = TCA_KIND,
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},
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.str = CLSACT,
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},
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};
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#undef ASCIIZ_LEN_CLSACT
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#undef CLSACT
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const int rv = send(fd, &req, sizeof(req), 0);
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if (rv == -1) return -errno;
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if (rv != sizeof(req)) return -EMSGSIZE;
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return processNetlinkResponse(fd);
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}
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int tcQdiscAddDevClsact(int fd, int ifIndex) {
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return doTcQdiscClsact(fd, ifIndex, RTM_NEWQDISC, NLM_F_EXCL | NLM_F_CREATE);
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}
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int tcQdiscReplaceDevClsact(int fd, int ifIndex) {
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return doTcQdiscClsact(fd, ifIndex, RTM_NEWQDISC, NLM_F_CREATE | NLM_F_REPLACE);
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}
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int tcQdiscDelDevClsact(int fd, int ifIndex) {
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return doTcQdiscClsact(fd, ifIndex, RTM_DELQDISC, 0);
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}
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// tc filter add dev .. ingress prio 1 protocol ipv6 bpf object-pinned /sys/fs/bpf/... direct-action
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int tcFilterAddDevBpf(int fd, int ifIndex, int bpfFd, bool ethernet) {
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// The priority doesn't matter until we actually start attaching multiple
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// things to the same interface's ingress point.
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const int prio = 1;
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// This is the name of the filter we're attaching (ie. this is the 'bpf'
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// packet classifier enabled by kernel config option CONFIG_NET_CLS_BPF.
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//
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// We go through some hoops in order to make this compile time constants
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// so that we can define the struct further down the function with the
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// field for this sized correctly already during the build.
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#define BPF "bpf"
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const char bpf[] = BPF;
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// sizeof() includes the terminating NULL
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#define ASCIIZ_LEN_BPF sizeof(bpf)
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// This is to replicate program name suffix used by 'tc' Linux cli
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// when it attaches programs.
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#define FSOBJ_SUFFIX ":[*fsobj]"
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// This macro expands (from header files) to:
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// prog_clatd_schedcls_ingress_clat_rawip:[*fsobj]
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// and is the name of the pinned ebpf program for ARPHRD_RAWIP interfaces.
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// (also compatible with anything that has 0 size L2 header)
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#define NAME_RAWIP CLAT_INGRESS_PROG_RAWIP_NAME FSOBJ_SUFFIX
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const char name_rawip[] = NAME_RAWIP;
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// This macro expands (from header files) to:
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// prog_clatd_schedcls_ingress_clat_ether:[*fsobj]
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// and is the name of the pinned ebpf program for ARPHRD_ETHER interfaces.
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// (also compatible with anything that has standard ethernet header)
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#define NAME_ETHER CLAT_INGRESS_PROG_ETHER_NAME FSOBJ_SUFFIX
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const char name_ether[] = NAME_ETHER;
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// The actual name we'll use is determined at run time via 'ethernet'
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// boolean. We need to compile time allocate enough space in the struct
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// hence this macro magic to make sure we have enough space for either
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// possibility. In practice both are actually the same size.
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#define ASCIIZ_MAXLEN_NAME \
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((sizeof(name_rawip) > sizeof(name_ether)) ? sizeof(name_rawip) : sizeof(name_ether))
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// This is not a compile time constant and is used in strcpy below
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#define NAME (ethernet ? NAME_ETHER : NAME_RAWIP)
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struct {
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nlmsghdr n;
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tcmsg t;
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struct {
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nlattr attr;
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char str[NLMSG_ALIGN(ASCIIZ_LEN_BPF)];
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} kind;
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struct {
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nlattr attr;
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struct {
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nlattr attr;
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__u32 u32;
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} fd;
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struct {
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nlattr attr;
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char str[NLMSG_ALIGN(ASCIIZ_MAXLEN_NAME)];
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} name;
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struct {
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nlattr attr;
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__u32 u32;
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} flags;
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} options;
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} req = {
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.n =
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{
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.nlmsg_len = sizeof(req),
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.nlmsg_type = RTM_NEWTFILTER,
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.nlmsg_flags = NETLINK_REQUEST_FLAGS | NLM_F_EXCL | NLM_F_CREATE,
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},
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.t =
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{
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.tcm_family = AF_UNSPEC,
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.tcm_ifindex = ifIndex,
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.tcm_handle = TC_H_UNSPEC,
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.tcm_parent = TC_H_MAKE(TC_H_CLSACT, TC_H_MIN_INGRESS),
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.tcm_info = (prio << 16) | htons(ETH_P_IPV6),
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},
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.kind =
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{
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.attr =
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{
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.nla_len = sizeof(req.kind),
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.nla_type = TCA_KIND,
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},
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.str = BPF,
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},
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.options =
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{
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.attr =
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{
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.nla_len = sizeof(req.options),
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.nla_type = TCA_OPTIONS,
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},
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.fd =
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{
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.attr =
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{
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.nla_len = sizeof(req.options.fd),
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.nla_type = TCA_BPF_FD,
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},
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.u32 = static_cast<__u32>(bpfFd),
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},
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.name =
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{
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.attr =
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{
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.nla_len = sizeof(req.options.name),
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.nla_type = TCA_BPF_NAME,
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},
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// Visible via 'tc filter show', but
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// is overwritten by strcpy below
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.str = "placeholder",
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},
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.flags =
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{
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.attr =
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{
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.nla_len = sizeof(req.options.flags),
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.nla_type = TCA_BPF_FLAGS,
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},
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.u32 = TCA_BPF_FLAG_ACT_DIRECT,
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},
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},
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};
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strncpy(req.options.name.str, NAME, sizeof(req.options.name.str));
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#undef NAME
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#undef ASCIIZ_MAXLEN_NAME
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#undef NAME_ETHER
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#undef NAME_RAWIP
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#undef NAME
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#undef ASCIIZ_LEN_BPF
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#undef BPF
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const int rv = send(fd, &req, sizeof(req), 0);
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if (rv == -1) return -errno;
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if (rv != sizeof(req)) return -EMSGSIZE;
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return processNetlinkResponse(fd);
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}
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} // namespace net
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} // namespace android
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