RouteController.cpp revision 4acd34a8e95b1191318216ebad409ec5e1b3d5f0
1/* 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 "RouteController.h" 18 19#include "Fwmark.h" 20#include "UidRanges.h" 21 22#define LOG_TAG "Netd" 23#include "log/log.h" 24#include "logwrap/logwrap.h" 25#include "resolv_netid.h" 26 27#include <arpa/inet.h> 28#include <fcntl.h> 29#include <linux/fib_rules.h> 30#include <map> 31#include <net/if.h> 32#include <sys/stat.h> 33 34namespace { 35 36// BEGIN CONSTANTS -------------------------------------------------------------------------------- 37 38const uint32_t RULE_PRIORITY_VPN_OVERRIDE_SYSTEM = 10000; 39// const uint32_t RULE_PRIORITY_VPN_OVERRIDE_LOCAL = 11000; 40const uint32_t RULE_PRIORITY_SECURE_VPN = 12000; 41const uint32_t RULE_PRIORITY_EXPLICIT_NETWORK = 13000; 42const uint32_t RULE_PRIORITY_OUTPUT_INTERFACE = 14000; 43const uint32_t RULE_PRIORITY_LEGACY_SYSTEM = 15000; 44const uint32_t RULE_PRIORITY_LEGACY_NETWORK = 16000; 45// const uint32_t RULE_PRIORITY_LOCAL_NETWORK = 17000; 46// const uint32_t RULE_PRIORITY_TETHERING = 18000; 47const uint32_t RULE_PRIORITY_IMPLICIT_NETWORK = 19000; 48// const uint32_t RULE_PRIORITY_BYPASSABLE_VPN = 20000; 49// const uint32_t RULE_PRIORITY_VPN_FALLTHROUGH = 21000; 50const uint32_t RULE_PRIORITY_DEFAULT_NETWORK = 22000; 51const uint32_t RULE_PRIORITY_DIRECTLY_CONNECTED = 23000; 52const uint32_t RULE_PRIORITY_UNREACHABLE = 24000; 53 54const uint32_t ROUTE_TABLE_LEGACY_NETWORK = 98; 55const uint32_t ROUTE_TABLE_LEGACY_SYSTEM = 99; 56 57const char* const ROUTE_TABLE_NAME_LEGACY_NETWORK = "legacy_network"; 58const char* const ROUTE_TABLE_NAME_LEGACY_SYSTEM = "legacy_system"; 59 60// TODO: These values aren't defined by the Linux kernel, because our UID routing changes are not 61// upstream (yet?), so we can't just pick them up from kernel headers. When (if?) the changes make 62// it upstream, we'll remove this and rely on the kernel header values. For now, add a static assert 63// that will warn us if upstream has given these values some other meaning. 64const uint16_t FRA_UID_START = 18; 65const uint16_t FRA_UID_END = 19; 66static_assert(FRA_UID_START > FRA_MAX, 67 "Android-specific FRA_UID_{START,END} values also assigned in Linux uapi. " 68 "Check that these values match what the kernel does and then update this assertion."); 69 70const uint16_t NETLINK_REQUEST_FLAGS = NLM_F_REQUEST | NLM_F_ACK; 71const uint16_t NETLINK_CREATE_REQUEST_FLAGS = NETLINK_REQUEST_FLAGS | NLM_F_CREATE | NLM_F_EXCL; 72 73const sockaddr_nl NETLINK_ADDRESS = {AF_NETLINK, 0, 0, 0}; 74 75const uint8_t AF_FAMILIES[] = {AF_INET, AF_INET6}; 76 77const char* const IP_VERSIONS[] = {"-4", "-6"}; 78 79const uid_t UID_ROOT = 0; 80const char* const OIF_NONE = NULL; 81const bool ACTION_ADD = true; 82const bool ACTION_DEL = false; 83const bool MODIFY_NON_UID_BASED_RULES = true; 84 85const char* const RT_TABLES_PATH = "/data/misc/net/rt_tables"; 86 87// Avoids "non-constant-expression cannot be narrowed from type 'unsigned int' to 'unsigned short'" 88// warnings when using RTA_LENGTH(x) inside static initializers (even when x is already uint16_t). 89constexpr uint16_t U16_RTA_LENGTH(uint16_t x) { 90 return RTA_LENGTH(x); 91} 92 93// These are practically const, but can't be declared so, because they are used to initialize 94// non-const pointers ("void* iov_base") in iovec arrays. 95rtattr FRATTR_PRIORITY = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_PRIORITY }; 96rtattr FRATTR_TABLE = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_TABLE }; 97rtattr FRATTR_FWMARK = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_FWMARK }; 98rtattr FRATTR_FWMASK = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_FWMASK }; 99rtattr FRATTR_UID_START = { U16_RTA_LENGTH(sizeof(uid_t)), FRA_UID_START }; 100rtattr FRATTR_UID_END = { U16_RTA_LENGTH(sizeof(uid_t)), FRA_UID_END }; 101 102rtattr RTATTR_TABLE = { U16_RTA_LENGTH(sizeof(uint32_t)), RTA_TABLE }; 103rtattr RTATTR_OIF = { U16_RTA_LENGTH(sizeof(uint32_t)), RTA_OIF }; 104 105uint8_t PADDING_BUFFER[RTA_ALIGNTO] = {0, 0, 0, 0}; 106 107// END CONSTANTS ---------------------------------------------------------------------------------- 108 109// No locks needed because RouteController is accessed only from one thread (in CommandListener). 110std::map<std::string, uint32_t> interfaceToTable; 111 112uint32_t getRouteTableForInterface(const char* interface) { 113 uint32_t index = if_nametoindex(interface); 114 if (index) { 115 index += RouteController::ROUTE_TABLE_OFFSET_FROM_INDEX; 116 interfaceToTable[interface] = index; 117 return index; 118 } 119 // If the interface goes away if_nametoindex() will return 0 but we still need to know 120 // the index so we can remove the rules and routes. 121 auto iter = interfaceToTable.find(interface); 122 if (iter == interfaceToTable.end()) { 123 ALOGE("cannot find interface %s", interface); 124 return RT_TABLE_UNSPEC; 125 } 126 return iter->second; 127} 128 129void addTableName(uint32_t table, const std::string& name, std::string* contents) { 130 char tableString[UINT32_STRLEN]; 131 snprintf(tableString, sizeof(tableString), "%u", table); 132 *contents += tableString; 133 *contents += " "; 134 *contents += name; 135 *contents += "\n"; 136} 137 138// Doesn't return success/failure as the file is optional; it's okay if we fail to update it. 139void updateTableNamesFile() { 140 std::string contents; 141 addTableName(ROUTE_TABLE_LEGACY_NETWORK, ROUTE_TABLE_NAME_LEGACY_NETWORK, &contents); 142 addTableName(ROUTE_TABLE_LEGACY_SYSTEM, ROUTE_TABLE_NAME_LEGACY_SYSTEM, &contents); 143 for (const auto& entry : interfaceToTable) { 144 addTableName(entry.second, entry.first, &contents); 145 } 146 147 mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH; // mode 0644, rw-r--r-- 148 int fd = open(RT_TABLES_PATH, O_CREAT | O_TRUNC | O_WRONLY | O_NOFOLLOW | O_CLOEXEC, mode); 149 if (fd == -1) { 150 ALOGE("failed to create %s (%s)", RT_TABLES_PATH, strerror(errno)); 151 return; 152 } 153 // File creation is affected by umask, so make sure the right mode bits are set. 154 if (fchmod(fd, mode) == -1) { 155 ALOGE("failed to chmod %s to mode 0%o (%s)", RT_TABLES_PATH, mode, strerror(errno)); 156 } 157 ssize_t bytesWritten = write(fd, contents.data(), contents.size()); 158 if (bytesWritten != static_cast<ssize_t>(contents.size())) { 159 ALOGE("failed to write to %s (%zd vs %zu bytes) (%s)", RT_TABLES_PATH, bytesWritten, 160 contents.size(), strerror(errno)); 161 } 162 close(fd); 163} 164 165// Sends a netlink request and expects an ack. 166// |iov| is an array of struct iovec that contains the netlink message payload. 167// The netlink header is generated by this function based on |action| and |flags|. 168// Returns -errno if there was an error or if the kernel reported an error. 169WARN_UNUSED_RESULT int sendNetlinkRequest(uint16_t action, uint16_t flags, iovec* iov, int iovlen) { 170 nlmsghdr nlmsg = { 171 .nlmsg_type = action, 172 .nlmsg_flags = flags, 173 }; 174 iov[0].iov_base = &nlmsg; 175 iov[0].iov_len = sizeof(nlmsg); 176 for (int i = 0; i < iovlen; ++i) { 177 nlmsg.nlmsg_len += iov[i].iov_len; 178 } 179 180 int ret; 181 struct { 182 nlmsghdr msg; 183 nlmsgerr err; 184 } response; 185 186 int sock = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE); 187 if (sock != -1 && 188 connect(sock, reinterpret_cast<const sockaddr*>(&NETLINK_ADDRESS), 189 sizeof(NETLINK_ADDRESS)) != -1 && 190 writev(sock, iov, iovlen) != -1 && 191 (ret = recv(sock, &response, sizeof(response), 0)) != -1) { 192 if (ret == sizeof(response)) { 193 ret = response.err.error; // Netlink errors are negative errno. 194 if (ret) { 195 ALOGE("netlink response contains error (%s)", strerror(-ret)); 196 } 197 } else { 198 ALOGE("bad netlink response message size (%d != %zu)", ret, sizeof(response)); 199 ret = -EBADMSG; 200 } 201 } else { 202 ALOGE("netlink socket/connect/writev/recv failed (%s)", strerror(errno)); 203 ret = -errno; 204 } 205 206 if (sock != -1) { 207 close(sock); 208 } 209 210 return ret; 211} 212 213// Adds or removes a routing rule for IPv4 and IPv6. 214// 215// + If |table| is non-zero, the rule points at the specified routing table. Otherwise, the rule 216// returns ENETUNREACH. 217// + If |mask| is non-zero, the rule matches the specified fwmark and mask. Otherwise, |fwmark| is 218// ignored. 219// + If |interface| is non-NULL, the rule matches the specified outgoing interface. 220// 221// Returns 0 on success or negative errno on failure. 222WARN_UNUSED_RESULT int modifyIpRule(uint16_t action, uint32_t priority, uint32_t table, 223 uint32_t fwmark, uint32_t mask, const char* interface, 224 uid_t uidStart, uid_t uidEnd) { 225 // Ensure that if you set a bit in the fwmark, it's not being ignored by the mask. 226 if (fwmark & ~mask) { 227 ALOGE("mask 0x%x does not select all the bits set in fwmark 0x%x", mask, fwmark); 228 return -ERANGE; 229 } 230 231 // The interface name must include exactly one terminating NULL and be properly padded, or older 232 // kernels will refuse to delete rules. 233 uint16_t paddingLength = 0; 234 size_t interfaceLength = 0; 235 char oifname[IFNAMSIZ]; 236 if (interface != OIF_NONE) { 237 interfaceLength = strlcpy(oifname, interface, IFNAMSIZ) + 1; 238 if (interfaceLength > IFNAMSIZ) { 239 ALOGE("interface name too long (%zu > %u)", interfaceLength, IFNAMSIZ); 240 return -ENAMETOOLONG; 241 } 242 paddingLength = RTA_SPACE(interfaceLength) - RTA_LENGTH(interfaceLength); 243 } 244 245 // Either both start and end UID must be specified, or neither. 246 if ((uidStart == INVALID_UID) != (uidEnd == INVALID_UID)) { 247 ALOGE("incompatible start and end UIDs (%u vs %u)", uidStart, uidEnd); 248 return -EUSERS; 249 } 250 bool isUidRule = (uidStart != INVALID_UID); 251 252 // Assemble a rule request and put it in an array of iovec structures. 253 fib_rule_hdr rule = { 254 .action = static_cast<uint8_t>(table != RT_TABLE_UNSPEC ? FR_ACT_TO_TBL : 255 FR_ACT_UNREACHABLE), 256 }; 257 258 rtattr fraOifname = { U16_RTA_LENGTH(interfaceLength), FRA_OIFNAME }; 259 260 iovec iov[] = { 261 { NULL, 0 }, 262 { &rule, sizeof(rule) }, 263 { &FRATTR_PRIORITY, sizeof(FRATTR_PRIORITY) }, 264 { &priority, sizeof(priority) }, 265 { &FRATTR_TABLE, table != RT_TABLE_UNSPEC ? sizeof(FRATTR_TABLE) : 0 }, 266 { &table, table != RT_TABLE_UNSPEC ? sizeof(table) : 0 }, 267 { &FRATTR_FWMARK, mask ? sizeof(FRATTR_FWMARK) : 0 }, 268 { &fwmark, mask ? sizeof(fwmark) : 0 }, 269 { &FRATTR_FWMASK, mask ? sizeof(FRATTR_FWMASK) : 0 }, 270 { &mask, mask ? sizeof(mask) : 0 }, 271 { &FRATTR_UID_START, isUidRule ? sizeof(FRATTR_UID_START) : 0 }, 272 { &uidStart, isUidRule ? sizeof(uidStart) : 0 }, 273 { &FRATTR_UID_END, isUidRule ? sizeof(FRATTR_UID_END) : 0 }, 274 { &uidEnd, isUidRule ? sizeof(uidEnd) : 0 }, 275 { &fraOifname, interface != OIF_NONE ? sizeof(fraOifname) : 0 }, 276 { oifname, interfaceLength }, 277 { PADDING_BUFFER, paddingLength }, 278 }; 279 280 uint16_t flags = (action == RTM_NEWRULE) ? NETLINK_CREATE_REQUEST_FLAGS : NETLINK_REQUEST_FLAGS; 281 for (size_t i = 0; i < ARRAY_SIZE(AF_FAMILIES); ++i) { 282 rule.family = AF_FAMILIES[i]; 283 if (int ret = sendNetlinkRequest(action, flags, iov, ARRAY_SIZE(iov))) { 284 return ret; 285 } 286 } 287 288 return 0; 289} 290 291// Adds or deletes an IPv4 or IPv6 route. 292// Returns 0 on success or negative errno on failure. 293WARN_UNUSED_RESULT int modifyIpRoute(uint16_t action, uint32_t table, const char* interface, 294 const char* destination, const char* nexthop) { 295 // At least the destination must be non-null. 296 if (!destination) { 297 ALOGE("null destination"); 298 return -EFAULT; 299 } 300 301 // Parse the prefix. 302 uint8_t rawAddress[sizeof(in6_addr)]; 303 uint8_t family; 304 uint8_t prefixLength; 305 int rawLength = parsePrefix(destination, &family, rawAddress, sizeof(rawAddress), 306 &prefixLength); 307 if (rawLength < 0) { 308 ALOGE("parsePrefix failed for destination %s (%s)", destination, strerror(-rawLength)); 309 return rawLength; 310 } 311 312 if (static_cast<size_t>(rawLength) > sizeof(rawAddress)) { 313 ALOGE("impossible! address too long (%d vs %zu)", rawLength, sizeof(rawAddress)); 314 return -ENOBUFS; // Cannot happen; parsePrefix only supports IPv4 and IPv6. 315 } 316 317 // If an interface was specified, find the ifindex. 318 uint32_t ifindex; 319 if (interface != OIF_NONE) { 320 ifindex = if_nametoindex(interface); 321 if (!ifindex) { 322 ALOGE("cannot find interface %s", interface); 323 return -ENODEV; 324 } 325 } 326 327 // If a nexthop was specified, parse it as the same family as the prefix. 328 uint8_t rawNexthop[sizeof(in6_addr)]; 329 if (nexthop && inet_pton(family, nexthop, rawNexthop) <= 0) { 330 ALOGE("inet_pton failed for nexthop %s", nexthop); 331 return -EINVAL; 332 } 333 334 // Assemble a rtmsg and put it in an array of iovec structures. 335 rtmsg route = { 336 .rtm_protocol = RTPROT_STATIC, 337 .rtm_type = RTN_UNICAST, 338 .rtm_family = family, 339 .rtm_dst_len = prefixLength, 340 }; 341 342 rtattr rtaDst = { U16_RTA_LENGTH(rawLength), RTA_DST }; 343 rtattr rtaGateway = { U16_RTA_LENGTH(rawLength), RTA_GATEWAY }; 344 345 iovec iov[] = { 346 { NULL, 0 }, 347 { &route, sizeof(route) }, 348 { &RTATTR_TABLE, sizeof(RTATTR_TABLE) }, 349 { &table, sizeof(table) }, 350 { &rtaDst, sizeof(rtaDst) }, 351 { rawAddress, static_cast<size_t>(rawLength) }, 352 { &RTATTR_OIF, interface != OIF_NONE ? sizeof(RTATTR_OIF) : 0 }, 353 { &ifindex, interface != OIF_NONE ? sizeof(ifindex) : 0 }, 354 { &rtaGateway, nexthop ? sizeof(rtaGateway) : 0 }, 355 { rawNexthop, nexthop ? static_cast<size_t>(rawLength) : 0 }, 356 }; 357 358 uint16_t flags = (action == RTM_NEWROUTE) ? NETLINK_CREATE_REQUEST_FLAGS : 359 NETLINK_REQUEST_FLAGS; 360 return sendNetlinkRequest(action, flags, iov, ARRAY_SIZE(iov)); 361} 362 363// Add rules to allow legacy routes added through the requestRouteToHost() API. 364WARN_UNUSED_RESULT int AddLegacyRouteRules() { 365 Fwmark fwmark; 366 Fwmark mask; 367 368 fwmark.explicitlySelected = false; 369 mask.explicitlySelected = true; 370 371 // Rules to allow legacy routes to override the default network. 372 if (int ret = modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_LEGACY_SYSTEM, ROUTE_TABLE_LEGACY_SYSTEM, 373 fwmark.intValue, mask.intValue, OIF_NONE, INVALID_UID, 374 INVALID_UID)) { 375 return ret; 376 } 377 if (int ret = modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_LEGACY_NETWORK, 378 ROUTE_TABLE_LEGACY_NETWORK, fwmark.intValue, 379 mask.intValue, OIF_NONE, INVALID_UID, INVALID_UID)) { 380 return ret; 381 } 382 383 fwmark.permission = PERMISSION_SYSTEM; 384 mask.permission = PERMISSION_SYSTEM; 385 386 // A rule to allow legacy routes from system apps to override VPNs. 387 return modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_VPN_OVERRIDE_SYSTEM, ROUTE_TABLE_LEGACY_SYSTEM, 388 fwmark.intValue, mask.intValue, OIF_NONE, INVALID_UID, INVALID_UID); 389} 390 391// Add a new rule to look up the 'main' table, with the same selectors as the "default network" 392// rule, but with a lower priority. Since the default network rule points to a table with a default 393// route, the rule we're adding will never be used for normal routing lookups. However, the kernel 394// may fall-through to it to find directly-connected routes when it validates that a nexthop (in a 395// route being added) is reachable. 396WARN_UNUSED_RESULT int AddDirectlyConnectedRule() { 397 Fwmark fwmark; 398 Fwmark mask; 399 400 fwmark.netId = NETID_UNSET; 401 mask.netId = FWMARK_NET_ID_MASK; 402 403 return modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_DIRECTLY_CONNECTED, RT_TABLE_MAIN, 404 fwmark.intValue, mask.intValue, OIF_NONE, UID_ROOT, UID_ROOT); 405} 406 407// Add a rule to preempt the pre-defined "from all lookup main" rule. Packets that reach this rule 408// will be null-routed, and won't fall-through to the main table. 409WARN_UNUSED_RESULT int AddUnreachableRule() { 410 return modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_UNREACHABLE, RT_TABLE_UNSPEC, MARK_UNSET, 411 MARK_UNSET, OIF_NONE, INVALID_UID, INVALID_UID); 412} 413 414// An iptables rule to mark incoming packets on a network with the netId of the network. 415// 416// This is so that the kernel can: 417// + Use the right fwmark for (and thus correctly route) replies (e.g.: TCP RST, ICMP errors, ping 418// replies, SYN-ACKs, etc). 419// + Mark sockets that accept connections from this interface so that the connection stays on the 420// same interface. 421WARN_UNUSED_RESULT int modifyIncomingPacketMark(unsigned netId, const char* interface, 422 Permission permission, bool add) { 423 Fwmark fwmark; 424 425 fwmark.netId = netId; 426 fwmark.explicitlySelected = true; 427 fwmark.protectedFromVpn = true; 428 fwmark.permission = permission; 429 430 char markString[UINT32_HEX_STRLEN]; 431 snprintf(markString, sizeof(markString), "0x%x", fwmark.intValue); 432 433 if (execIptables(V4V6, "-t", "mangle", add ? "-A" : "-D", "INPUT", "-i", interface, "-j", 434 "MARK", "--set-mark", markString, NULL)) { 435 ALOGE("failed to change iptables rule that sets incoming packet mark"); 436 return -EREMOTEIO; 437 } 438 439 return 0; 440} 441 442// A rule to route traffic based on an explicitly chosen network. 443// 444// Supports apps that use the multinetwork APIs to restrict their traffic to a network. 445// 446// Even though we check permissions at the time we set a netId into the fwmark of a socket, we need 447// to check it again in the rules here, because a network's permissions may have been updated via 448// modifyNetworkPermission(). 449WARN_UNUSED_RESULT int modifyExplicitNetworkRule(unsigned netId, uint32_t table, 450 Permission permission, uid_t uidStart, 451 uid_t uidEnd, bool add) { 452 Fwmark fwmark; 453 Fwmark mask; 454 455 fwmark.netId = netId; 456 mask.netId = FWMARK_NET_ID_MASK; 457 458 fwmark.explicitlySelected = true; 459 mask.explicitlySelected = true; 460 461 fwmark.permission = permission; 462 mask.permission = permission; 463 464 return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_EXPLICIT_NETWORK, table, 465 fwmark.intValue, mask.intValue, OIF_NONE, uidStart, uidEnd); 466} 467 468// A rule to route traffic based on a chosen outgoing interface. 469// 470// Supports apps that use SO_BINDTODEVICE or IP_PKTINFO options and the kernel that already knows 471// the outgoing interface (typically for link-local communications). 472WARN_UNUSED_RESULT int modifyOutputInterfaceRule(const char* interface, uint32_t table, 473 Permission permission, uid_t uidStart, 474 uid_t uidEnd, bool add) { 475 Fwmark fwmark; 476 Fwmark mask; 477 478 fwmark.permission = permission; 479 mask.permission = permission; 480 481 return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_OUTPUT_INTERFACE, table, 482 fwmark.intValue, mask.intValue, interface, uidStart, uidEnd); 483} 484 485// A rule to route traffic based on the chosen network. 486// 487// This is for sockets that have not explicitly requested a particular network, but have been 488// bound to one when they called connect(). This ensures that sockets connected on a particular 489// network stay on that network even if the default network changes. 490WARN_UNUSED_RESULT int modifyImplicitNetworkRule(unsigned netId, uint32_t table, 491 Permission permission, bool add) { 492 Fwmark fwmark; 493 Fwmark mask; 494 495 fwmark.netId = netId; 496 mask.netId = FWMARK_NET_ID_MASK; 497 498 fwmark.explicitlySelected = false; 499 mask.explicitlySelected = true; 500 501 fwmark.permission = permission; 502 mask.permission = permission; 503 504 return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_IMPLICIT_NETWORK, table, 505 fwmark.intValue, mask.intValue, OIF_NONE, INVALID_UID, INVALID_UID); 506} 507 508// A rule to route all traffic from a given set of UIDs to go over the VPN. 509// 510// Notice that this rule doesn't use the netId. I.e., no matter what netId the user's socket may 511// have, if they are subject to this VPN, their traffic has to go through it. Allows the traffic to 512// bypass the VPN if the protectedFromVpn bit is set. 513WARN_UNUSED_RESULT int modifyVpnUidRangeRule(uint32_t table, uid_t uidStart, uid_t uidEnd, 514 bool add) { 515 Fwmark fwmark; 516 Fwmark mask; 517 518 fwmark.protectedFromVpn = false; 519 mask.protectedFromVpn = true; 520 521 return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_SECURE_VPN, table, 522 fwmark.intValue, mask.intValue, OIF_NONE, uidStart, uidEnd); 523} 524 525// A rule to allow system apps to send traffic over this VPN even if they are not part of the target 526// set of UIDs. 527// 528// This is needed for DnsProxyListener to correctly resolve a request for a user who is in the 529// target set, but where the DnsProxyListener itself is not. 530WARN_UNUSED_RESULT int modifyVpnSystemPermissionRule(unsigned netId, uint32_t table, bool add) { 531 Fwmark fwmark; 532 Fwmark mask; 533 534 fwmark.netId = netId; 535 mask.netId = FWMARK_NET_ID_MASK; 536 537 fwmark.permission = PERMISSION_SYSTEM; 538 mask.permission = PERMISSION_SYSTEM; 539 540 return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_SECURE_VPN, table, 541 fwmark.intValue, mask.intValue, OIF_NONE, INVALID_UID, INVALID_UID); 542} 543 544WARN_UNUSED_RESULT int modifyPhysicalNetwork(unsigned netId, const char* interface, 545 Permission permission, bool add) { 546 uint32_t table = getRouteTableForInterface(interface); 547 if (table == RT_TABLE_UNSPEC) { 548 return -ESRCH; 549 } 550 551 if (int ret = modifyIncomingPacketMark(netId, interface, permission, add)) { 552 return ret; 553 } 554 if (int ret = modifyExplicitNetworkRule(netId, table, permission, INVALID_UID, INVALID_UID, 555 add)) { 556 return ret; 557 } 558 if (int ret = modifyOutputInterfaceRule(interface, table, permission, INVALID_UID, INVALID_UID, 559 add)) { 560 return ret; 561 } 562 return modifyImplicitNetworkRule(netId, table, permission, add); 563} 564 565WARN_UNUSED_RESULT int modifyVirtualNetwork(unsigned netId, const char* interface, 566 const UidRanges& uidRanges, bool add, 567 bool modifyNonUidBasedRules) { 568 uint32_t table = getRouteTableForInterface(interface); 569 if (table == RT_TABLE_UNSPEC) { 570 return -ESRCH; 571 } 572 573 for (const UidRanges::Range& range : uidRanges.getRanges()) { 574 if (int ret = modifyExplicitNetworkRule(netId, table, PERMISSION_NONE, range.first, 575 range.second, add)) { 576 return ret; 577 } 578 if (int ret = modifyOutputInterfaceRule(interface, table, PERMISSION_NONE, range.first, 579 range.second, add)) { 580 return ret; 581 } 582 if (int ret = modifyVpnUidRangeRule(table, range.first, range.second, add)) { 583 return ret; 584 } 585 } 586 587 if (modifyNonUidBasedRules) { 588 if (int ret = modifyIncomingPacketMark(netId, interface, PERMISSION_NONE, add)) { 589 return ret; 590 } 591 if (int ret = modifyExplicitNetworkRule(netId, table, PERMISSION_NONE, UID_ROOT, UID_ROOT, 592 add)) { 593 return ret; 594 } 595 return modifyVpnSystemPermissionRule(netId, table, add); 596 } 597 598 return 0; 599} 600 601WARN_UNUSED_RESULT int modifyDefaultNetwork(uint16_t action, const char* interface, 602 Permission permission) { 603 uint32_t table = getRouteTableForInterface(interface); 604 if (table == RT_TABLE_UNSPEC) { 605 return -ESRCH; 606 } 607 608 Fwmark fwmark; 609 Fwmark mask; 610 611 fwmark.netId = NETID_UNSET; 612 mask.netId = FWMARK_NET_ID_MASK; 613 614 fwmark.permission = permission; 615 mask.permission = permission; 616 617 return modifyIpRule(action, RULE_PRIORITY_DEFAULT_NETWORK, table, fwmark.intValue, 618 mask.intValue, OIF_NONE, INVALID_UID, INVALID_UID); 619} 620 621// Adds or removes an IPv4 or IPv6 route to the specified table and, if it's a directly-connected 622// route, to the main table as well. 623// Returns 0 on success or negative errno on failure. 624WARN_UNUSED_RESULT int modifyRoute(uint16_t action, const char* interface, const char* destination, 625 const char* nexthop, RouteController::TableType tableType) { 626 uint32_t table; 627 switch (tableType) { 628 case RouteController::INTERFACE: { 629 table = getRouteTableForInterface(interface); 630 if (table == RT_TABLE_UNSPEC) { 631 return -ESRCH; 632 } 633 break; 634 } 635 case RouteController::LEGACY_NETWORK: { 636 table = ROUTE_TABLE_LEGACY_NETWORK; 637 break; 638 } 639 case RouteController::LEGACY_SYSTEM: { 640 table = ROUTE_TABLE_LEGACY_SYSTEM; 641 break; 642 } 643 } 644 645 int ret = modifyIpRoute(action, table, interface, destination, nexthop); 646 // We allow apps to call requestRouteToHost() multiple times with the same route, so ignore 647 // EEXIST failures when adding routes to legacy tables. 648 if (ret && !(action == RTM_NEWROUTE && ret == -EEXIST && 649 tableType != RouteController::INTERFACE)) { 650 return ret; 651 } 652 653 // If there's no nexthop, this is a directly connected route. Add it to the main table also, to 654 // let the kernel find it when validating nexthops when global routes are added. 655 if (!nexthop) { 656 ret = modifyIpRoute(action, RT_TABLE_MAIN, interface, destination, NULL); 657 // A failure with action == ADD && errno == EEXIST means that the route already exists in 658 // the main table, perhaps because the kernel added it automatically as part of adding the 659 // IP address to the interface. Ignore this, but complain about everything else. 660 if (ret && !(action == RTM_NEWROUTE && ret == -EEXIST)) { 661 return ret; 662 } 663 } 664 665 return 0; 666} 667 668// Returns 0 on success or negative errno on failure. 669WARN_UNUSED_RESULT int flushRoutes(const char* interface) { 670 uint32_t table = getRouteTableForInterface(interface); 671 if (table == RT_TABLE_UNSPEC) { 672 return -ESRCH; 673 } 674 675 char tableString[UINT32_STRLEN]; 676 snprintf(tableString, sizeof(tableString), "%u", table); 677 678 for (size_t i = 0; i < ARRAY_SIZE(IP_VERSIONS); ++i) { 679 const char* argv[] = { 680 IP_PATH, 681 IP_VERSIONS[i], 682 "route", 683 "flush", 684 "table", 685 tableString, 686 }; 687 if (android_fork_execvp(ARRAY_SIZE(argv), const_cast<char**>(argv), NULL, false, false)) { 688 ALOGE("failed to flush routes"); 689 return -EREMOTEIO; 690 } 691 } 692 693 interfaceToTable.erase(interface); 694 return 0; 695} 696 697} // namespace 698 699int RouteController::Init() { 700 if (int ret = AddDirectlyConnectedRule()) { 701 return ret; 702 } 703 if (int ret = AddLegacyRouteRules()) { 704 return ret; 705 } 706 // TODO: Enable once we are sure everything works. 707 if (false) { 708 if (int ret = AddUnreachableRule()) { 709 return ret; 710 } 711 } 712 updateTableNamesFile(); 713 return 0; 714} 715 716int RouteController::addInterfaceToPhysicalNetwork(unsigned netId, const char* interface, 717 Permission permission) { 718 if (int ret = modifyPhysicalNetwork(netId, interface, permission, ACTION_ADD)) { 719 return ret; 720 } 721 updateTableNamesFile(); 722 return 0; 723} 724 725int RouteController::removeInterfaceFromPhysicalNetwork(unsigned netId, const char* interface, 726 Permission permission) { 727 if (int ret = modifyPhysicalNetwork(netId, interface, permission, ACTION_DEL)) { 728 return ret; 729 } 730 if (int ret = flushRoutes(interface)) { 731 return ret; 732 } 733 updateTableNamesFile(); 734 return 0; 735} 736 737int RouteController::addInterfaceToVirtualNetwork(unsigned netId, const char* interface, 738 const UidRanges& uidRanges) { 739 if (int ret = modifyVirtualNetwork(netId, interface, uidRanges, ACTION_ADD, 740 MODIFY_NON_UID_BASED_RULES)) { 741 return ret; 742 } 743 updateTableNamesFile(); 744 return 0; 745} 746 747int RouteController::removeInterfaceFromVirtualNetwork(unsigned netId, const char* interface, 748 const UidRanges& uidRanges) { 749 if (int ret = modifyVirtualNetwork(netId, interface, uidRanges, ACTION_DEL, 750 MODIFY_NON_UID_BASED_RULES)) { 751 return ret; 752 } 753 if (int ret = flushRoutes(interface)) { 754 return ret; 755 } 756 updateTableNamesFile(); 757 return 0; 758} 759 760int RouteController::modifyPhysicalNetworkPermission(unsigned netId, const char* interface, 761 Permission oldPermission, 762 Permission newPermission) { 763 // Add the new rules before deleting the old ones, to avoid race conditions. 764 if (int ret = modifyPhysicalNetwork(netId, interface, newPermission, ACTION_ADD)) { 765 return ret; 766 } 767 return modifyPhysicalNetwork(netId, interface, oldPermission, ACTION_DEL); 768} 769 770int RouteController::addUsersToVirtualNetwork(unsigned netId, const char* interface, 771 const UidRanges& uidRanges) { 772 return modifyVirtualNetwork(netId, interface, uidRanges, ACTION_ADD, 773 !MODIFY_NON_UID_BASED_RULES); 774} 775 776int RouteController::removeUsersFromVirtualNetwork(unsigned netId, const char* interface, 777 const UidRanges& uidRanges) { 778 return modifyVirtualNetwork(netId, interface, uidRanges, ACTION_DEL, 779 !MODIFY_NON_UID_BASED_RULES); 780} 781 782int RouteController::addInterfaceToDefaultNetwork(const char* interface, Permission permission) { 783 return modifyDefaultNetwork(RTM_NEWRULE, interface, permission); 784} 785 786int RouteController::removeInterfaceFromDefaultNetwork(const char* interface, 787 Permission permission) { 788 return modifyDefaultNetwork(RTM_DELRULE, interface, permission); 789} 790 791int RouteController::addRoute(const char* interface, const char* destination, const char* nexthop, 792 TableType tableType) { 793 return modifyRoute(RTM_NEWROUTE, interface, destination, nexthop, tableType); 794} 795 796int RouteController::removeRoute(const char* interface, const char* destination, 797 const char* nexthop, TableType tableType) { 798 return modifyRoute(RTM_DELROUTE, interface, destination, nexthop, tableType); 799} 800