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Sreeram Ramachandran030b36e2014-05-11 21:04:03 -07001/*
2 * Copyright (C) 2014 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#include "FwmarkServer.h"
18
19#include "Fwmark.h"
Sreeram Ramachandranf4cfad32014-05-21 08:54:07 -070020#include "FwmarkCommand.h"
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -070021#include "NetworkController.h"
Sreeram Ramachandranec008842014-05-21 14:01:16 -070022#include "resolv_netid.h"
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -070023
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -070024#include <sys/socket.h>
25#include <unistd.h>
26
Sreeram Ramachandranf4f6c8d2014-06-23 09:54:06 -070027FwmarkServer::FwmarkServer(NetworkController* networkController) :
28 SocketListener("fwmarkd", true), mNetworkController(networkController) {
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -070029}
30
31bool FwmarkServer::onDataAvailable(SocketClient* client) {
Sreeram Ramachandrane09b20a2014-07-05 17:15:14 -070032 int socketFd = -1;
33 int error = processClient(client, &socketFd);
34 if (socketFd >= 0) {
35 close(socketFd);
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -070036 }
37
38 // Always send a response even if there were connection errors or read errors, so that we don't
39 // inadvertently cause the client to hang (which always waits for a response).
40 client->sendData(&error, sizeof(error));
41
42 // Always close the client connection (by returning false). This prevents a DoS attack where
43 // the client issues multiple commands on the same connection, never reading the responses,
44 // causing its receive buffer to fill up, and thus causing our client->sendData() to block.
45 return false;
46}
47
Sreeram Ramachandrane09b20a2014-07-05 17:15:14 -070048int FwmarkServer::processClient(SocketClient* client, int* socketFd) {
Sreeram Ramachandranefbe05d2014-05-21 11:41:39 -070049 FwmarkCommand command;
50
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -070051 iovec iov;
Sreeram Ramachandranefbe05d2014-05-21 11:41:39 -070052 iov.iov_base = &command;
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -070053 iov.iov_len = sizeof(command);
54
55 msghdr message;
56 memset(&message, 0, sizeof(message));
57 message.msg_iov = &iov;
58 message.msg_iovlen = 1;
59
60 union {
61 cmsghdr cmh;
Sreeram Ramachandrane09b20a2014-07-05 17:15:14 -070062 char cmsg[CMSG_SPACE(sizeof(*socketFd))];
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -070063 } cmsgu;
64
65 memset(cmsgu.cmsg, 0, sizeof(cmsgu.cmsg));
66 message.msg_control = cmsgu.cmsg;
67 message.msg_controllen = sizeof(cmsgu.cmsg);
68
69 int messageLength = TEMP_FAILURE_RETRY(recvmsg(client->getSocket(), &message, 0));
70 if (messageLength <= 0) {
Sreeram Ramachandran3a069e62014-06-22 11:02:57 -070071 return -errno;
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -070072 }
73
Sreeram Ramachandranefbe05d2014-05-21 11:41:39 -070074 if (messageLength != sizeof(command)) {
Sreeram Ramachandran3a069e62014-06-22 11:02:57 -070075 return -EBADMSG;
Sreeram Ramachandranefbe05d2014-05-21 11:41:39 -070076 }
77
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -070078 cmsghdr* const cmsgh = CMSG_FIRSTHDR(&message);
79 if (cmsgh && cmsgh->cmsg_level == SOL_SOCKET && cmsgh->cmsg_type == SCM_RIGHTS &&
Sreeram Ramachandrane09b20a2014-07-05 17:15:14 -070080 cmsgh->cmsg_len == CMSG_LEN(sizeof(*socketFd))) {
81 memcpy(socketFd, CMSG_DATA(cmsgh), sizeof(*socketFd));
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -070082 }
83
Sreeram Ramachandrane09b20a2014-07-05 17:15:14 -070084 if (*socketFd < 0) {
Sreeram Ramachandran3a069e62014-06-22 11:02:57 -070085 return -EBADF;
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -070086 }
87
88 Fwmark fwmark;
Sreeram Ramachandran5ff58d42014-05-14 09:57:31 -070089 socklen_t fwmarkLen = sizeof(fwmark.intValue);
Sreeram Ramachandrane09b20a2014-07-05 17:15:14 -070090 if (getsockopt(*socketFd, SOL_SOCKET, SO_MARK, &fwmark.intValue, &fwmarkLen) == -1) {
Sreeram Ramachandran3a069e62014-06-22 11:02:57 -070091 return -errno;
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -070092 }
93
Sreeram Ramachandrana675b002014-07-05 11:00:55 -070094 Permission permission = mNetworkController->getPermissionForUser(client->getUid());
Sreeram Ramachandranec008842014-05-21 14:01:16 -070095
Sreeram Ramachandranefbe05d2014-05-21 11:41:39 -070096 switch (command.cmdId) {
97 case FwmarkCommand::ON_ACCEPT: {
Sreeram Ramachandran070b2d22014-07-11 17:06:12 -070098 // Called after a socket accept(). The kernel would've marked the NetId and necessary
Sreeram Ramachandrana675b002014-07-05 11:00:55 -070099 // permissions bits, so we just add the rest of the user's permissions here.
100 permission = static_cast<Permission>(permission | fwmark.permission);
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -0700101 break;
102 }
103
Sreeram Ramachandranefbe05d2014-05-21 11:41:39 -0700104 case FwmarkCommand::ON_CONNECT: {
Sreeram Ramachandran070b2d22014-07-11 17:06:12 -0700105 // Called before a socket connect() happens. Set the default network's NetId into the
106 // fwmark so that the socket routes consistently over that network. Do this even if the
107 // socket already has a NetId, so that calling connect() multiple times still works.
108 //
109 // But respect the existing NetId if it had been explicitly preferred, indicated by:
110 // + The explicit bit having been set.
111 // + Or, the NetId being that of a VPN, which indicates a proxy acting on behalf of a
112 // user who is subject to the VPN. The explicit bit is not set so that it works even
113 // if the VPN is a split tunnel, but it's an explicit network preference nonetheless.
114 if (!fwmark.explicitlySelected && !mNetworkController->isVirtualNetwork(fwmark.netId)) {
Sreeram Ramachandranefbe05d2014-05-21 11:41:39 -0700115 fwmark.netId = mNetworkController->getDefaultNetwork();
116 }
117 break;
118 }
119
120 case FwmarkCommand::SELECT_NETWORK: {
Sreeram Ramachandranec008842014-05-21 14:01:16 -0700121 fwmark.netId = command.netId;
122 if (command.netId == NETID_UNSET) {
123 fwmark.explicitlySelected = false;
Sreeram Ramachandrane09b20a2014-07-05 17:15:14 -0700124 fwmark.protectedFromVpn = false;
125 permission = PERMISSION_NONE;
126 } else if (mNetworkController->canUserSelectNetwork(client->getUid(), command.netId)) {
Sreeram Ramachandranec008842014-05-21 14:01:16 -0700127 fwmark.explicitlySelected = true;
Sreeram Ramachandrane09b20a2014-07-05 17:15:14 -0700128 fwmark.protectedFromVpn = mNetworkController->canProtect(client->getUid());
129 } else {
130 return -EPERM;
Sreeram Ramachandranec008842014-05-21 14:01:16 -0700131 }
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -0700132 break;
133 }
134
Sreeram Ramachandranefbe05d2014-05-21 11:41:39 -0700135 case FwmarkCommand::PROTECT_FROM_VPN: {
Sreeram Ramachandrane09b20a2014-07-05 17:15:14 -0700136 if (!mNetworkController->canProtect(client->getUid())) {
137 return -EPERM;
138 }
139 fwmark.protectedFromVpn = true;
140 permission = static_cast<Permission>(permission | fwmark.permission);
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -0700141 break;
142 }
143
Sreeram Ramachandrana69d9472014-07-11 16:27:02 -0700144 case FwmarkCommand::SELECT_FOR_USER: {
145 if ((permission & PERMISSION_SYSTEM) != PERMISSION_SYSTEM) {
146 return -EPERM;
147 }
148 fwmark.netId = mNetworkController->getNetworkForUser(command.uid, NETID_UNSET, false);
149 fwmark.protectedFromVpn = true;
150 break;
151 }
152
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -0700153 default: {
154 // unknown command
Sreeram Ramachandran3a069e62014-06-22 11:02:57 -0700155 return -EPROTO;
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -0700156 }
157 }
158
Sreeram Ramachandrana675b002014-07-05 11:00:55 -0700159 fwmark.permission = permission;
160
Sreeram Ramachandrane09b20a2014-07-05 17:15:14 -0700161 if (setsockopt(*socketFd, SOL_SOCKET, SO_MARK, &fwmark.intValue,
162 sizeof(fwmark.intValue)) == -1) {
Sreeram Ramachandran3a069e62014-06-22 11:02:57 -0700163 return -errno;
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -0700164 }
165
Sreeram Ramachandran3a069e62014-06-22 11:02:57 -0700166 return 0;
Sreeram Ramachandran030b36e2014-05-11 21:04:03 -0700167}