| /* |
| * Copyright (C) 2014 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. |
| */ |
| |
| #include "FwmarkServer.h" |
| |
| #include <net/if.h> |
| #include <netinet/in.h> |
| #include <selinux/selinux.h> |
| #include <sys/socket.h> |
| #include <unistd.h> |
| #include <utils/String16.h> |
| |
| #include <android-base/cmsg.h> |
| #include <android-base/logging.h> |
| #include <android-base/properties.h> |
| #include <binder/IServiceManager.h> |
| #include <netd_resolv/resolv.h> // NETID_UNSET |
| |
| #include "Fwmark.h" |
| #include "FwmarkCommand.h" |
| #include "NetdConstants.h" |
| #include "NetworkController.h" |
| |
| #include "NetdUpdatablePublic.h" |
| |
| using android::base::ReceiveFileDescriptorVector; |
| using android::base::unique_fd; |
| using android::net::metrics::INetdEventListener; |
| |
| namespace android { |
| namespace net { |
| |
| FwmarkServer::FwmarkServer(NetworkController* networkController, EventReporter* eventReporter) |
| : SocketListener(SOCKET_NAME, true), |
| mNetworkController(networkController), |
| mEventReporter(eventReporter) {} |
| |
| bool FwmarkServer::onDataAvailable(SocketClient* client) { |
| int socketFd = -1; |
| int error = processClient(client, &socketFd); |
| if (socketFd >= 0) { |
| close(socketFd); |
| } |
| |
| // Always send a response even if there were connection errors or read errors, so that we don't |
| // inadvertently cause the client to hang (which always waits for a response). |
| client->sendData(&error, sizeof(error)); |
| |
| // Always close the client connection (by returning false). This prevents a DoS attack where |
| // the client issues multiple commands on the same connection, never reading the responses, |
| // causing its receive buffer to fill up, and thus causing our client->sendData() to block. |
| return false; |
| } |
| |
| static bool hasDestinationAddress(FwmarkCommand::CmdId cmdId) { |
| switch (cmdId) { |
| case FwmarkCommand::ON_CONNECT: |
| case FwmarkCommand::ON_CONNECT_COMPLETE: |
| case FwmarkCommand::ON_SENDMSG: |
| case FwmarkCommand::ON_SENDMMSG: |
| case FwmarkCommand::ON_SENDTO: |
| return true; |
| default: |
| return false; |
| } |
| } |
| |
| int FwmarkServer::processClient(SocketClient* client, int* socketFd) { |
| struct { |
| FwmarkCommand command; |
| FwmarkConnectInfo connectInfo; |
| } buf; |
| |
| // make sure there is no spurious padding |
| static_assert(sizeof(buf) == sizeof(buf.command) + sizeof(buf.connectInfo)); |
| |
| std::vector<unique_fd> received_fds; |
| ssize_t messageLength = |
| ReceiveFileDescriptorVector(client->getSocket(), &buf, sizeof(buf), 1, &received_fds); |
| |
| if (messageLength < 0) { |
| return -errno; |
| } else if (messageLength == 0) { |
| return -ESHUTDOWN; |
| } |
| |
| const FwmarkCommand &command = buf.command; |
| const FwmarkConnectInfo &connectInfo = buf.connectInfo; |
| |
| size_t expectedLen = sizeof(command); |
| if (hasDestinationAddress(command.cmdId)) { |
| expectedLen += sizeof(connectInfo); |
| } |
| |
| if (messageLength != static_cast<ssize_t>(expectedLen)) { |
| return -EBADMSG; |
| } |
| |
| Permission permission = mNetworkController->getPermissionForUser(client->getUid()); |
| |
| if (command.cmdId == FwmarkCommand::QUERY_USER_ACCESS) { |
| if ((permission & PERMISSION_SYSTEM) != PERMISSION_SYSTEM) { |
| return -EPERM; |
| } |
| return mNetworkController->checkUserNetworkAccess(command.uid, command.netId); |
| } |
| |
| if (received_fds.size() != 1) { |
| LOG(ERROR) << "FwmarkServer received " << received_fds.size() << " fds from client?"; |
| return -EBADF; |
| } else if (received_fds[0] < 0) { |
| LOG(ERROR) << "FwmarkServer received fd -1 from ReceiveFileDescriptorVector?"; |
| return -EBADF; |
| } |
| |
| *socketFd = received_fds[0].release(); |
| |
| int family; |
| socklen_t familyLen = sizeof(family); |
| if (getsockopt(*socketFd, SOL_SOCKET, SO_DOMAIN, &family, &familyLen) == -1) { |
| return -errno; |
| } |
| if (!FwmarkCommand::isSupportedFamily(family)) { |
| return -EAFNOSUPPORT; |
| } |
| |
| Fwmark fwmark; |
| socklen_t fwmarkLen = sizeof(fwmark.intValue); |
| if (getsockopt(*socketFd, SOL_SOCKET, SO_MARK, &fwmark.intValue, &fwmarkLen) == -1) { |
| return -errno; |
| } |
| |
| switch (command.cmdId) { |
| case FwmarkCommand::ON_ACCEPT: { |
| // Called after a socket accept(). The kernel would've marked the NetId and necessary |
| // permissions bits, so we just add the rest of the user's permissions here. |
| permission = static_cast<Permission>(permission | fwmark.permission); |
| break; |
| } |
| |
| case FwmarkCommand::ON_CONNECT: { |
| // Called before a socket connect() happens. Set an appropriate NetId into the fwmark so |
| // that the socket routes consistently over that network. Do this even if the socket |
| // already has a NetId, so that calling connect() multiple times still works. |
| // |
| // But if the explicit bit was set, the existing NetId was explicitly preferred (and not |
| // a case of connect() being called multiple times). Don't reset the NetId in that case. |
| // |
| // An "appropriate" NetId is the NetId of a bypassable VPN that applies to the user, or |
| // failing that, the default network. We'll never set the NetId of a secure VPN here. |
| // See the comments in the implementation of getNetworkForConnect() for more details. |
| // |
| // If the protect bit is set, this could be either a system proxy (e.g.: the dns proxy |
| // or the download manager) acting on behalf of another user, or a VPN provider. If it's |
| // a proxy, we shouldn't reset the NetId. If it's a VPN provider, we should set the |
| // default network's NetId. |
| // |
| // There's no easy way to tell the difference between a proxy and a VPN app. We can't |
| // use PERMISSION_SYSTEM to identify the proxy because a VPN app may also have those |
| // permissions. So we use the following heuristic: |
| // |
| // If it's a proxy, but the existing NetId is not a VPN, that means the user (that the |
| // proxy is acting on behalf of) is not subject to a VPN, so the proxy must have picked |
| // the default network's NetId. So, it's okay to replace that with the current default |
| // network's NetId (which in all likelihood is the same). |
| // |
| // Conversely, if it's a VPN provider, the existing NetId cannot be a VPN. The only time |
| // we set a VPN's NetId into a socket without setting the explicit bit is here, in |
| // ON_CONNECT, but we won't do that if the socket has the protect bit set. |
| // If the VPN provider connect()ed (and got the VPN NetId set) and then called |
| // protect(), we would've unset the NetId in PROTECT_FROM_VPN below. |
| // |
| // So, overall (when the explicit bit is not set but the protect bit is set), if the |
| // existing NetId is a VPN, don't reset it. Else, set the default network's NetId. |
| if (!fwmark.explicitlySelected) { |
| if (family == AF_INET6 && connectInfo.addr.sin6.sin6_scope_id && |
| IN6_IS_ADDR_LINKLOCAL(&connectInfo.addr.sin6.sin6_addr)) { |
| fwmark.netId = mNetworkController->getNetworkForInterface( |
| connectInfo.addr.sin6.sin6_scope_id); |
| } else if (!fwmark.protectedFromVpn) { |
| fwmark.netId = mNetworkController->getNetworkForConnect(client->getUid()); |
| } else if (!mNetworkController->isVirtualNetwork(fwmark.netId)) { |
| fwmark.netId = mNetworkController->getDefaultNetwork(); |
| } |
| } |
| break; |
| } |
| |
| case FwmarkCommand::ON_CONNECT_COMPLETE: { |
| // Called after a socket connect() completes. |
| // This reports connect event including netId, destination IP address, destination port, |
| // uid, connect latency, and connect errno if any. |
| |
| // Skip reporting if connect() happened on a UDP socket. |
| int socketProto; |
| socklen_t intSize = sizeof(socketProto); |
| const int ret = getsockopt(*socketFd, SOL_SOCKET, SO_PROTOCOL, &socketProto, &intSize); |
| if ((ret != 0) || (socketProto == IPPROTO_UDP)) { |
| break; |
| } |
| |
| android::sp<android::net::metrics::INetdEventListener> netdEventListener = |
| mEventReporter->getNetdEventListener(); |
| |
| if (netdEventListener != nullptr) { |
| char addrstr[INET6_ADDRSTRLEN + IFNAMSIZ]; // ipv6 address + optional %scope |
| char portstr[sizeof("65535")]; |
| static_assert(sizeof(addrstr) >= 62); |
| static_assert(sizeof(portstr) >= 6); |
| const int ret = getnameinfo(&connectInfo.addr.s, sizeof(connectInfo.addr.s), |
| addrstr, sizeof(addrstr), portstr, sizeof(portstr), |
| NI_NUMERICHOST | NI_NUMERICSERV); |
| |
| netdEventListener->onConnectEvent(fwmark.netId, connectInfo.error, |
| connectInfo.latencyMs, |
| (ret == 0) ? String16(addrstr) : String16(""), |
| (ret == 0) ? strtoul(portstr, nullptr, 10) : 0, client->getUid()); |
| } |
| break; |
| } |
| |
| case FwmarkCommand::ON_SENDMMSG: |
| case FwmarkCommand::ON_SENDMSG: |
| case FwmarkCommand::ON_SENDTO: { |
| return 0; |
| } |
| |
| case FwmarkCommand::SELECT_NETWORK: { |
| fwmark.netId = command.netId; |
| if (command.netId == NETID_UNSET) { |
| fwmark.explicitlySelected = false; |
| fwmark.protectedFromVpn = false; |
| permission = PERMISSION_NONE; |
| } else { |
| if (int ret = mNetworkController->checkUserNetworkAccess(client->getUid(), |
| command.netId)) { |
| return ret; |
| } |
| fwmark.explicitlySelected = true; |
| fwmark.protectedFromVpn = |
| mNetworkController->canProtect(client->getUid(), command.netId); |
| } |
| break; |
| } |
| |
| case FwmarkCommand::PROTECT_FROM_VPN: { |
| // TODO: Add support to specify netId in protectFromVpn(). Currently, NetdClient always |
| // passes NETID_UNSET |
| if (!mNetworkController->canProtect(client->getUid(), fwmark.netId)) { |
| LOG(ERROR) << "uid " << client->getUid() << " protect from VPN failed."; |
| return -EPERM; |
| } |
| // If a bypassable VPN's provider app calls connect() and then protect(), it will end up |
| // with a socket that looks like that of a system proxy but is not (see comments for |
| // ON_CONNECT above). So, reset the NetId. |
| // |
| // In any case, it's appropriate that if the socket has an implicit VPN NetId mark, the |
| // PROTECT_FROM_VPN command should unset it. |
| if (!fwmark.explicitlySelected && mNetworkController->isVirtualNetwork(fwmark.netId)) { |
| fwmark.netId = mNetworkController->getDefaultNetwork(); |
| } |
| fwmark.protectedFromVpn = true; |
| permission = static_cast<Permission>(permission | fwmark.permission); |
| break; |
| } |
| |
| case FwmarkCommand::SELECT_FOR_USER: { |
| if ((permission & PERMISSION_SYSTEM) != PERMISSION_SYSTEM) { |
| return -EPERM; |
| } |
| fwmark.netId = mNetworkController->getNetworkForUser(command.uid); |
| fwmark.protectedFromVpn = true; |
| break; |
| } |
| |
| case FwmarkCommand::TAG_SOCKET: { |
| // If the UID is -1, tag as the caller's UID: |
| // - TrafficStats and NetworkManagementSocketTagger use -1 to indicate "use the |
| // caller's UID". |
| // - xt_qtaguid will see -1 on the command line, fail to parse it as a uint32_t, |
| // and fall back to current_fsuid(). |
| uid_t tagUid = command.uid; |
| if (static_cast<int>(tagUid) == -1) tagUid = client->getUid(); |
| return libnetd_updatable_tagSocket(*socketFd, command.trafficCtrlInfo, tagUid, |
| client->getUid()); |
| } |
| |
| case FwmarkCommand::UNTAG_SOCKET: { |
| // Any process can untag a socket it has an fd for. |
| return libnetd_updatable_untagSocket(*socketFd); |
| } |
| |
| default: { |
| // unknown command |
| return -EPROTO; |
| } |
| } |
| |
| fwmark.permission = permission; |
| |
| if (setsockopt(*socketFd, SOL_SOCKET, SO_MARK, &fwmark.intValue, |
| sizeof(fwmark.intValue)) == -1) { |
| return -errno; |
| } |
| |
| return 0; |
| } |
| |
| } // namespace net |
| } // namespace android |
