RouteController.cpp revision ed4bd1f7d219f9f5f56763ea02cf4947e78397f6
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 26#include <arpa/inet.h> 27#include <linux/fib_rules.h> 28#include <map> 29#include <net/if.h> 30 31namespace { 32 33// BEGIN CONSTANTS -------------------------------------------------------------------------------- 34 35const uint32_t RULE_PRIORITY_VPN_OVERRIDES = 11000; 36const uint32_t RULE_PRIORITY_SECURE_VPN = 12000; 37const uint32_t RULE_PRIORITY_EXPLICIT_NETWORK = 13000; 38const uint32_t RULE_PRIORITY_OUTPUT_INTERFACE = 14000; 39const uint32_t RULE_PRIORITY_PRIVILEGED_LEGACY = 16000; 40const uint32_t RULE_PRIORITY_LEGACY = 17000; 41const uint32_t RULE_PRIORITY_IMPLICIT_NETWORK = 18000; 42const uint32_t RULE_PRIORITY_DEFAULT_NETWORK = 21000; 43const uint32_t RULE_PRIORITY_DIRECTLY_CONNECTED = 22000; 44// TODO: Uncomment once we are sure everything works. 45#if 0 46const uint32_t RULE_PRIORITY_UNREACHABLE = 23000; 47#endif 48 49// TODO: These values aren't defined by the Linux kernel, because our UID routing changes are not 50// upstream (yet?), so we can't just pick them up from kernel headers. When (if?) the changes make 51// it upstream, we'll remove this and rely on the kernel header values. For now, add a static assert 52// that will warn us if upstream has given these values some other meaning. 53const uint16_t FRA_UID_START = 18; 54const uint16_t FRA_UID_END = 19; 55static_assert(FRA_UID_START > FRA_MAX, 56 "Android-specific FRA_UID_{START,END} values also assigned in Linux uapi. " 57 "Check that these values match what the kernel does and then update this assertion."); 58 59const uint16_t NETLINK_REQUEST_FLAGS = NLM_F_REQUEST | NLM_F_ACK; 60const uint16_t NETLINK_CREATE_REQUEST_FLAGS = NETLINK_REQUEST_FLAGS | NLM_F_CREATE | NLM_F_EXCL; 61 62const sockaddr_nl NETLINK_ADDRESS = {AF_NETLINK, 0, 0, 0}; 63 64const uint8_t AF_FAMILIES[] = {AF_INET, AF_INET6}; 65 66const char* const IP_VERSIONS[] = {"-4", "-6"}; 67 68// Avoids "non-constant-expression cannot be narrowed from type 'unsigned int' to 'unsigned short'" 69// warnings when using RTA_LENGTH(x) inside static initializers (even when x is already uint16_t). 70constexpr uint16_t U16_RTA_LENGTH(uint16_t x) { 71 return RTA_LENGTH(x); 72} 73 74// These are practically const, but can't be declared so, because they are used to initialize 75// non-const pointers ("void* iov_base") in iovec arrays. 76rtattr FRATTR_PRIORITY = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_PRIORITY }; 77rtattr FRATTR_TABLE = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_TABLE }; 78rtattr FRATTR_FWMARK = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_FWMARK }; 79rtattr FRATTR_FWMASK = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_FWMASK }; 80rtattr FRATTR_UID_START = { U16_RTA_LENGTH(sizeof(uid_t)), FRA_UID_START }; 81rtattr FRATTR_UID_END = { U16_RTA_LENGTH(sizeof(uid_t)), FRA_UID_END }; 82 83rtattr RTATTR_TABLE = { U16_RTA_LENGTH(sizeof(uint32_t)), RTA_TABLE }; 84rtattr RTATTR_OIF = { U16_RTA_LENGTH(sizeof(uint32_t)), RTA_OIF }; 85 86uint8_t PADDING_BUFFER[RTA_ALIGNTO] = {0, 0, 0, 0}; 87 88// END CONSTANTS ---------------------------------------------------------------------------------- 89 90std::map<std::string, uint32_t> interfaceToIndex; 91 92uint32_t getRouteTableForInterface(const char* interface) { 93 uint32_t index = if_nametoindex(interface); 94 if (index) { 95 interfaceToIndex[interface] = index; 96 } else { 97 // If the interface goes away if_nametoindex() will return 0 but we still need to know 98 // the index so we can remove the rules and routes. 99 std::map<std::string, uint32_t>::iterator it = interfaceToIndex.find(interface); 100 if (it != interfaceToIndex.end()) { 101 index = it->second; 102 } 103 } 104 return index ? index + RouteController::ROUTE_TABLE_OFFSET_FROM_INDEX : 0; 105} 106 107// Sends a netlink request and expects an ack. 108// |iov| is an array of struct iovec that contains the netlink message payload. 109// The netlink header is generated by this function based on |action| and |flags|. 110// Returns -errno if there was an error or if the kernel reported an error. 111WARN_UNUSED_RESULT int sendNetlinkRequest(uint16_t action, uint16_t flags, iovec* iov, int iovlen) { 112 nlmsghdr nlmsg = { 113 .nlmsg_type = action, 114 .nlmsg_flags = flags, 115 }; 116 iov[0].iov_base = &nlmsg; 117 iov[0].iov_len = sizeof(nlmsg); 118 for (int i = 0; i < iovlen; ++i) { 119 nlmsg.nlmsg_len += iov[i].iov_len; 120 } 121 122 int ret; 123 struct { 124 nlmsghdr msg; 125 nlmsgerr err; 126 } response; 127 128 int sock = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE); 129 if (sock != -1 && 130 connect(sock, reinterpret_cast<const sockaddr*>(&NETLINK_ADDRESS), 131 sizeof(NETLINK_ADDRESS)) != -1 && 132 writev(sock, iov, iovlen) != -1 && 133 (ret = recv(sock, &response, sizeof(response), 0)) != -1) { 134 if (ret == sizeof(response)) { 135 ret = response.err.error; // Netlink errors are negative errno. 136 if (ret) { 137 ALOGE("netlink response contains error (%s)", strerror(-ret)); 138 } 139 } else { 140 ALOGE("bad netlink response message size (%d != %zu)", ret, sizeof(response)); 141 ret = -EBADMSG; 142 } 143 } else { 144 ALOGE("netlink socket/connect/writev/recv failed (%s)", strerror(errno)); 145 ret = -errno; 146 } 147 148 if (sock != -1) { 149 close(sock); 150 } 151 152 return ret; 153} 154 155// Adds or removes a routing rule for IPv4 and IPv6. 156// 157// + If |table| is non-zero, the rule points at the specified routing table. Otherwise, the rule 158// returns ENETUNREACH. 159// + If |mask| is non-zero, the rule matches the specified fwmark and mask. Otherwise, |fwmark| is 160// ignored. 161// + If |interface| is non-NULL, the rule matches the specified outgoing interface. 162// 163// Returns 0 on success or negative errno on failure. 164WARN_UNUSED_RESULT int modifyIpRule(uint16_t action, uint32_t priority, uint32_t table, 165 uint32_t fwmark, uint32_t mask, const char* interface, 166 uid_t uidStart, uid_t uidEnd) { 167 // Ensure that if you set a bit in the fwmark, it's not being ignored by the mask. 168 if (fwmark & ~mask) { 169 ALOGE("mask 0x%x does not select all the bits set in fwmark 0x%x", mask, fwmark); 170 return -ERANGE; 171 } 172 173 // The interface name must include exactly one terminating NULL and be properly padded, or older 174 // kernels will refuse to delete rules. 175 uint16_t paddingLength = 0; 176 size_t interfaceLength = 0; 177 char oifname[IFNAMSIZ]; 178 if (interface) { 179 interfaceLength = strlcpy(oifname, interface, IFNAMSIZ) + 1; 180 if (interfaceLength > IFNAMSIZ) { 181 ALOGE("interface name too long (%zu > %u)", interfaceLength, IFNAMSIZ); 182 return -ENAMETOOLONG; 183 } 184 paddingLength = RTA_SPACE(interfaceLength) - RTA_LENGTH(interfaceLength); 185 } 186 187 // Either both start and end UID must be specified, or neither. 188 if ((uidStart == INVALID_UID) != (uidEnd == INVALID_UID)) { 189 ALOGE("incompatible start and end UIDs (%u vs %u)", uidStart, uidEnd); 190 return -EUSERS; 191 } 192 bool isUidRule = (uidStart != INVALID_UID); 193 194 // Assemble a rule request and put it in an array of iovec structures. 195 fib_rule_hdr rule = { 196 .action = static_cast<uint8_t>(table ? FR_ACT_TO_TBL : FR_ACT_UNREACHABLE), 197 }; 198 199 rtattr fraOifname = { U16_RTA_LENGTH(interfaceLength), FRA_OIFNAME }; 200 201 iovec iov[] = { 202 { NULL, 0 }, 203 { &rule, sizeof(rule) }, 204 { &FRATTR_PRIORITY, sizeof(FRATTR_PRIORITY) }, 205 { &priority, sizeof(priority) }, 206 { &FRATTR_TABLE, table ? sizeof(FRATTR_TABLE) : 0 }, 207 { &table, table ? sizeof(table) : 0 }, 208 { &FRATTR_FWMARK, mask ? sizeof(FRATTR_FWMARK) : 0 }, 209 { &fwmark, mask ? sizeof(fwmark) : 0 }, 210 { &FRATTR_FWMASK, mask ? sizeof(FRATTR_FWMASK) : 0 }, 211 { &mask, mask ? sizeof(mask) : 0 }, 212 { &FRATTR_UID_START, isUidRule ? sizeof(FRATTR_UID_START) : 0 }, 213 { &uidStart, isUidRule ? sizeof(uidStart) : 0 }, 214 { &FRATTR_UID_END, isUidRule ? sizeof(FRATTR_UID_END) : 0 }, 215 { &uidEnd, isUidRule ? sizeof(uidEnd) : 0 }, 216 { &fraOifname, interface ? sizeof(fraOifname) : 0 }, 217 { oifname, interfaceLength }, 218 { PADDING_BUFFER, paddingLength }, 219 }; 220 221 uint16_t flags = (action == RTM_NEWRULE) ? NETLINK_CREATE_REQUEST_FLAGS : NETLINK_REQUEST_FLAGS; 222 for (size_t i = 0; i < ARRAY_SIZE(AF_FAMILIES); ++i) { 223 rule.family = AF_FAMILIES[i]; 224 if (int ret = sendNetlinkRequest(action, flags, iov, ARRAY_SIZE(iov))) { 225 return ret; 226 } 227 } 228 229 return 0; 230} 231 232// Adds or deletes an IPv4 or IPv6 route. 233// Returns 0 on success or negative errno on failure. 234WARN_UNUSED_RESULT int modifyIpRoute(uint16_t action, uint32_t table, const char* interface, 235 const char* destination, const char* nexthop) { 236 // At least the destination must be non-null. 237 if (!destination) { 238 ALOGE("null destination"); 239 return -EFAULT; 240 } 241 242 // Parse the prefix. 243 uint8_t rawAddress[sizeof(in6_addr)]; 244 uint8_t family; 245 uint8_t prefixLength; 246 int rawLength = parsePrefix(destination, &family, rawAddress, sizeof(rawAddress), 247 &prefixLength); 248 if (rawLength < 0) { 249 ALOGE("parsePrefix failed for destination %s (%s)", destination, strerror(-rawLength)); 250 return rawLength; 251 } 252 253 if (static_cast<size_t>(rawLength) > sizeof(rawAddress)) { 254 ALOGE("impossible! address too long (%d vs %zu)", rawLength, sizeof(rawAddress)); 255 return -ENOBUFS; // Cannot happen; parsePrefix only supports IPv4 and IPv6. 256 } 257 258 // If an interface was specified, find the ifindex. 259 uint32_t ifindex; 260 if (interface) { 261 ifindex = if_nametoindex(interface); 262 if (!ifindex) { 263 ALOGE("cannot find interface %s", interface); 264 return -ENODEV; 265 } 266 } 267 268 // If a nexthop was specified, parse it as the same family as the prefix. 269 uint8_t rawNexthop[sizeof(in6_addr)]; 270 if (nexthop && inet_pton(family, nexthop, rawNexthop) <= 0) { 271 ALOGE("inet_pton failed for nexthop %s", nexthop); 272 return -EINVAL; 273 } 274 275 // Assemble a rtmsg and put it in an array of iovec structures. 276 rtmsg route = { 277 .rtm_protocol = RTPROT_STATIC, 278 .rtm_type = RTN_UNICAST, 279 .rtm_family = family, 280 .rtm_dst_len = prefixLength, 281 }; 282 283 rtattr rtaDst = { U16_RTA_LENGTH(rawLength), RTA_DST }; 284 rtattr rtaGateway = { U16_RTA_LENGTH(rawLength), RTA_GATEWAY }; 285 286 iovec iov[] = { 287 { NULL, 0 }, 288 { &route, sizeof(route) }, 289 { &RTATTR_TABLE, sizeof(RTATTR_TABLE) }, 290 { &table, sizeof(table) }, 291 { &rtaDst, sizeof(rtaDst) }, 292 { rawAddress, static_cast<size_t>(rawLength) }, 293 { &RTATTR_OIF, interface ? sizeof(RTATTR_OIF) : 0 }, 294 { &ifindex, interface ? sizeof(ifindex) : 0 }, 295 { &rtaGateway, nexthop ? sizeof(rtaGateway) : 0 }, 296 { rawNexthop, nexthop ? static_cast<size_t>(rawLength) : 0 }, 297 }; 298 299 uint16_t flags = (action == RTM_NEWROUTE) ? NETLINK_CREATE_REQUEST_FLAGS : 300 NETLINK_REQUEST_FLAGS; 301 return sendNetlinkRequest(action, flags, iov, ARRAY_SIZE(iov)); 302} 303 304WARN_UNUSED_RESULT int modifyIncomingPacketMark(unsigned netId, const char* interface, bool add) { 305 // An iptables rule to mark incoming packets on a network with the netId of the network. 306 // 307 // This is so that the kernel can: 308 // + Use the right fwmark for (and thus correctly route) replies (e.g.: TCP RST, ICMP errors, 309 // ping replies, SYN-ACKs, etc). 310 // + Mark sockets that accept connections from this interface so that the connection stays on 311 // the same interface. 312 char markString[UINT32_HEX_STRLEN]; 313 snprintf(markString, sizeof(markString), "0x%x", netId); 314 if (execIptables(V4V6, "-t", "mangle", add ? "-A" : "-D", "INPUT", "-i", interface, "-j", 315 "MARK", "--set-mark", markString, NULL)) { 316 ALOGE("failed to change iptables rule that sets incoming packet mark"); 317 return -EREMOTEIO; 318 } 319 return 0; 320} 321 322// A rule to let UID 0 (as a proxy for the kernel) access the routes on a given network. 323WARN_UNUSED_RESULT int modifyKernelAccessRule(uint16_t action, unsigned netId, uint32_t priority, 324 uint32_t table) { 325 Fwmark fwmark; 326 Fwmark mask; 327 328 fwmark.netId = netId; 329 mask.netId = FWMARK_NET_ID_MASK; 330 331 return modifyIpRule(action, priority, table, fwmark.intValue, mask.intValue, NULL, 0, 0); 332} 333 334WARN_UNUSED_RESULT int modifyPerNetworkRules(unsigned netId, const char* interface, uint32_t table, 335 Permission permission, uid_t uidStart, uid_t uidEnd, 336 bool add, bool modifyInterfaceBasedRules) { 337 if (!table) { 338 table = getRouteTableForInterface(interface); 339 if (!table) { 340 ALOGE("cannot find interface %s", interface); 341 return -ESRCH; 342 } 343 } 344 345 uint16_t action = add ? RTM_NEWRULE : RTM_DELRULE; 346 347 Fwmark fwmark; 348 Fwmark mask; 349 350 // A rule to route traffic based on a chosen outgoing interface. 351 // 352 // Supports apps that use SO_BINDTODEVICE or IP_PKTINFO options and the kernel that already 353 // knows the outgoing interface (typically for link-local communications). 354 fwmark.permission = permission; 355 mask.permission = permission; 356 if (int ret = modifyIpRule(action, RULE_PRIORITY_OUTPUT_INTERFACE, table, fwmark.intValue, 357 mask.intValue, interface, uidStart, uidEnd)) { 358 return ret; 359 } 360 361 // A rule to route traffic based on the chosen network. 362 // 363 // This is for sockets that have not explicitly requested a particular network, but have been 364 // bound to one when they called connect(). This ensures that sockets connected on a particular 365 // network stay on that network even if the default network changes. 366 fwmark.netId = netId; 367 mask.netId = FWMARK_NET_ID_MASK; 368 if (int ret = modifyIpRule(action, RULE_PRIORITY_IMPLICIT_NETWORK, table, fwmark.intValue, 369 mask.intValue, NULL, uidStart, uidEnd)) { 370 return ret; 371 } 372 373 // A rule to route traffic based on an explicitly chosen network. 374 // 375 // Supports apps that use the multinetwork APIs to restrict their traffic to a network. 376 // 377 // Even though we check permissions at the time we set a netId into the fwmark of a socket, we 378 // still need to check it again in the rules here, because a network's permissions may have been 379 // updated via modifyNetworkPermission(). 380 fwmark.explicitlySelected = true; 381 mask.explicitlySelected = true; 382 if (int ret = modifyIpRule(action, RULE_PRIORITY_EXPLICIT_NETWORK, table, fwmark.intValue, 383 mask.intValue, NULL, uidStart, uidEnd)) { 384 return ret; 385 } 386 387 if (permission != PERMISSION_NONE) { 388 if (int ret = modifyKernelAccessRule(action, netId, RULE_PRIORITY_IMPLICIT_NETWORK, 389 table)) { 390 return ret; 391 } 392 } 393 394 if (modifyInterfaceBasedRules) { 395 if (int ret = modifyIncomingPacketMark(netId, interface, add)) { 396 return ret; 397 } 398 } 399 400 return 0; 401} 402 403// Adds or removes rules for VPNs that affect UIDs in |uidRanges|. If |modifyInterfaceBasedRules| 404// is true, also modifies the rules that are based only on the |interface| and not on |uidRanges|. 405// When adding or removing an interface to the VPN, set it to true. When adding or removing UIDs 406// without changing the VPN's interfaces, set it to false. 407WARN_UNUSED_RESULT int modifyVpnRules(unsigned netId, const char* interface, 408 const UidRanges& uidRanges, bool add, 409 bool modifyInterfaceBasedRules) { 410 uint32_t table = getRouteTableForInterface(interface); 411 if (!table) { 412 ALOGE("cannot find interface %s", interface); 413 return -ESRCH; 414 } 415 416 uint16_t action = add ? RTM_NEWRULE : RTM_DELRULE; 417 418 Fwmark fwmark; 419 Fwmark mask; 420 421 fwmark.protectedFromVpn = false; 422 mask.protectedFromVpn = true; 423 424 for (const std::pair<uid_t, uid_t>& range : uidRanges.getRanges()) { 425 if (int ret = modifyPerNetworkRules(netId, interface, table, PERMISSION_NONE, range.first, 426 range.second, add, false)) { 427 return ret; 428 } 429 430 // A rule to route all traffic from a given set of UIDs to go over the VPN. 431 // 432 // Notice that this rule doesn't use the netId. I.e., no matter what netId the user's socket 433 // may have, if they are subject to this VPN, their traffic has to go through it. Allows the 434 // traffic to bypass the VPN if the protectedFromVpn bit is set. 435 if (int ret = modifyIpRule(action, RULE_PRIORITY_SECURE_VPN, table, fwmark.intValue, 436 mask.intValue, NULL, range.first, range.second)) { 437 return ret; 438 } 439 } 440 441 if (modifyInterfaceBasedRules) { 442 if (int ret = modifyKernelAccessRule(action, netId, RULE_PRIORITY_IMPLICIT_NETWORK, 443 table)) { 444 return ret; 445 } 446 447 if (int ret = modifyIncomingPacketMark(netId, interface, add)) { 448 return ret; 449 } 450 451 // A rule to allow privileged apps to send traffic over this VPN even if they are not part 452 // of the target set of UIDs. 453 // 454 // This is needed for DnsProxyListener to correctly resolve a request for a user who is in 455 // the target set, but where the DnsProxyListener itself is not. 456 fwmark.protectedFromVpn = false; 457 mask.protectedFromVpn = false; 458 459 fwmark.netId = netId; 460 mask.netId = FWMARK_NET_ID_MASK; 461 462 fwmark.permission = PERMISSION_SYSTEM; 463 mask.permission = PERMISSION_SYSTEM; 464 465 if (int ret = modifyIpRule(action, RULE_PRIORITY_SECURE_VPN, table, fwmark.intValue, 466 mask.intValue, NULL, INVALID_UID, INVALID_UID)) { 467 return ret; 468 } 469 } 470 471 return 0; 472} 473 474WARN_UNUSED_RESULT int modifyDefaultNetworkRules(uint16_t action, const char* interface, 475 Permission permission) { 476 uint32_t table = getRouteTableForInterface(interface); 477 if (!table) { 478 ALOGE("cannot find interface %s", interface); 479 return -ESRCH; 480 } 481 482 Fwmark fwmark; 483 Fwmark mask; 484 485 fwmark.netId = 0; 486 mask.netId = FWMARK_NET_ID_MASK; 487 488 fwmark.permission = permission; 489 mask.permission = permission; 490 491 if (int ret = modifyIpRule(action, RULE_PRIORITY_DEFAULT_NETWORK, table, fwmark.intValue, 492 mask.intValue, NULL, INVALID_UID, INVALID_UID)) { 493 return ret; 494 } 495 496 if (permission != PERMISSION_NONE) { 497 if (int ret = modifyKernelAccessRule(action, 0, RULE_PRIORITY_DEFAULT_NETWORK, table)) { 498 return ret; 499 } 500 } 501 502 return 0; 503} 504 505// Adds or removes an IPv4 or IPv6 route to the specified table and, if it's a directly-connected 506// route, to the main table as well. 507// Returns 0 on success or negative errno on failure. 508WARN_UNUSED_RESULT int modifyRoute(uint16_t action, const char* interface, const char* destination, 509 const char* nexthop, RouteController::TableType tableType) { 510 uint32_t table = 0; 511 switch (tableType) { 512 case RouteController::INTERFACE: { 513 table = getRouteTableForInterface(interface); 514 break; 515 } 516 case RouteController::LEGACY: { 517 table = RouteController::ROUTE_TABLE_LEGACY; 518 break; 519 } 520 case RouteController::PRIVILEGED_LEGACY: { 521 table = RouteController::ROUTE_TABLE_PRIVILEGED_LEGACY; 522 break; 523 } 524 } 525 if (!table) { 526 ALOGE("cannot find table for interface %s and tableType %d", interface, tableType); 527 return -ESRCH; 528 } 529 530 int ret = modifyIpRoute(action, table, interface, destination, nexthop); 531 // We allow apps to call requestRouteToHost() multiple times with the same route, so ignore 532 // EEXIST failures when adding routes to legacy tables. 533 if (ret != 0 && !(action == RTM_NEWROUTE && ret == -EEXIST && 534 (tableType == RouteController::LEGACY || 535 tableType == RouteController::PRIVILEGED_LEGACY))) { 536 return ret; 537 } 538 539 // If there's no nexthop, this is a directly connected route. Add it to the main table also, to 540 // let the kernel find it when validating nexthops when global routes are added. 541 if (!nexthop) { 542 ret = modifyIpRoute(action, RT_TABLE_MAIN, interface, destination, NULL); 543 // A failure with action == ADD && errno == EEXIST means that the route already exists in 544 // the main table, perhaps because the kernel added it automatically as part of adding the 545 // IP address to the interface. Ignore this, but complain about everything else. 546 if (ret && !(action == RTM_NEWROUTE && ret == -EEXIST)) { 547 return ret; 548 } 549 } 550 551 return 0; 552} 553 554// Returns 0 on success or negative errno on failure. 555WARN_UNUSED_RESULT int flushRoutes(const char* interface) { 556 uint32_t table = getRouteTableForInterface(interface); 557 if (!table) { 558 ALOGE("cannot find interface %s", interface); 559 return -ESRCH; 560 } 561 interfaceToIndex.erase(interface); 562 563 char tableString[UINT32_STRLEN]; 564 snprintf(tableString, sizeof(tableString), "%u", table); 565 566 for (size_t i = 0; i < ARRAY_SIZE(IP_VERSIONS); ++i) { 567 const char* argv[] = { 568 IP_PATH, 569 IP_VERSIONS[i], 570 "route", 571 "flush", 572 "table", 573 tableString, 574 }; 575 if (android_fork_execvp(ARRAY_SIZE(argv), const_cast<char**>(argv), NULL, false, false)) { 576 ALOGE("failed to flush routes"); 577 return -EREMOTEIO; 578 } 579 } 580 581 return 0; 582} 583 584} // namespace 585 586int RouteController::Init() { 587 // Add a new rule to look up the 'main' table, with the same selectors as the "default network" 588 // rule, but with a lower priority. Since the default network rule points to a table with a 589 // default route, the rule we're adding will never be used for normal routing lookups. However, 590 // the kernel may fall-through to it to find directly-connected routes when it validates that a 591 // nexthop (in a route being added) is reachable. 592 if (int ret = modifyKernelAccessRule(RTM_NEWRULE, 0, RULE_PRIORITY_DIRECTLY_CONNECTED, 593 RT_TABLE_MAIN)) { 594 return ret; 595 } 596 597 Fwmark fwmark; 598 Fwmark mask; 599 600 // Add rules to allow legacy routes to override the default network. 601 fwmark.explicitlySelected = false; 602 mask.explicitlySelected = true; 603 604 if (int ret = modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_PRIVILEGED_LEGACY, 605 RouteController::ROUTE_TABLE_PRIVILEGED_LEGACY, fwmark.intValue, 606 mask.intValue, NULL, INVALID_UID, INVALID_UID)) { 607 return ret; 608 } 609 610 if (int ret = modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_LEGACY, 611 RouteController::ROUTE_TABLE_LEGACY, fwmark.intValue, mask.intValue, 612 NULL, INVALID_UID, INVALID_UID)) { 613 return ret; 614 } 615 616 // Add a rule to allow legacy routes from system apps to override VPNs. 617 fwmark.permission = PERMISSION_SYSTEM; 618 mask.permission = PERMISSION_SYSTEM; 619 620 if (int ret = modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_VPN_OVERRIDES, 621 RouteController::ROUTE_TABLE_PRIVILEGED_LEGACY, fwmark.intValue, 622 mask.intValue, NULL, INVALID_UID, INVALID_UID)) { 623 return ret; 624 } 625 626// TODO: Uncomment once we are sure everything works. 627#if 0 628 // Add a rule to preempt the pre-defined "from all lookup main" rule. Packets that reach this 629 // rule will be null-routed, and won't fall-through to the main table. 630 return modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_UNREACHABLE, 0, 0, 0, NULL, INVALID_UID, 631 INVALID_UID); 632#else 633 return 0; 634#endif 635} 636 637int RouteController::addInterfaceToNetwork(unsigned netId, const char* interface, 638 Permission permission) { 639 return modifyPerNetworkRules(netId, interface, 0, permission, INVALID_UID, INVALID_UID, true, 640 true); 641} 642 643int RouteController::removeInterfaceFromNetwork(unsigned netId, const char* interface, 644 Permission permission) { 645 if (int ret = modifyPerNetworkRules(netId, interface, 0, permission, INVALID_UID, INVALID_UID, 646 false, true)) { 647 return ret; 648 } 649 return flushRoutes(interface); 650} 651 652int RouteController::addInterfaceToVpn(unsigned netId, const char* interface, 653 const UidRanges& uidRanges) { 654 return modifyVpnRules(netId, interface, uidRanges, true, true); 655} 656 657int RouteController::removeInterfaceFromVpn(unsigned netId, const char* interface, 658 const UidRanges& uidRanges) { 659 if (int ret = modifyVpnRules(netId, interface, uidRanges, false, true)) { 660 return ret; 661 } 662 return flushRoutes(interface); 663} 664 665int RouteController::modifyNetworkPermission(unsigned netId, const char* interface, 666 Permission oldPermission, Permission newPermission) { 667 // Add the new rules before deleting the old ones, to avoid race conditions. 668 if (int ret = modifyPerNetworkRules(netId, interface, 0, newPermission, INVALID_UID, 669 INVALID_UID, true, false)) { 670 return ret; 671 } 672 return modifyPerNetworkRules(netId, interface, 0, oldPermission, INVALID_UID, INVALID_UID, 673 false, false); 674} 675 676int RouteController::addUsersToVpn(unsigned netId, const char* interface, 677 const UidRanges& uidRanges) { 678 return modifyVpnRules(netId, interface, uidRanges, true, false); 679} 680 681int RouteController::removeUsersFromVpn(unsigned netId, const char* interface, 682 const UidRanges& uidRanges) { 683 return modifyVpnRules(netId, interface, uidRanges, false, false); 684} 685 686int RouteController::addToDefaultNetwork(const char* interface, Permission permission) { 687 return modifyDefaultNetworkRules(RTM_NEWRULE, interface, permission); 688} 689 690int RouteController::removeFromDefaultNetwork(const char* interface, Permission permission) { 691 return modifyDefaultNetworkRules(RTM_DELRULE, interface, permission); 692} 693 694int RouteController::addRoute(const char* interface, const char* destination, const char* nexthop, 695 TableType tableType) { 696 return modifyRoute(RTM_NEWROUTE, interface, destination, nexthop, tableType); 697} 698 699int RouteController::removeRoute(const char* interface, const char* destination, 700 const char* nexthop, TableType tableType) { 701 return modifyRoute(RTM_DELROUTE, interface, destination, nexthop, tableType); 702} 703