RouteController.cpp revision 5ad4e98f7b566ffde39491ee4e80d4a15507f053
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#include "DummyNetwork.h" 22 23#define LOG_TAG "Netd" 24#include "log/log.h" 25#include "logwrap/logwrap.h" 26#include "netutils/ifc.h" 27#include "resolv_netid.h" 28 29#include <arpa/inet.h> 30#include <fcntl.h> 31#include <linux/fib_rules.h> 32#include <map> 33#include <net/if.h> 34#include <sys/stat.h> 35 36namespace { 37 38// BEGIN CONSTANTS -------------------------------------------------------------------------------- 39 40const uint32_t RULE_PRIORITY_VPN_OVERRIDE_SYSTEM = 10000; 41const uint32_t RULE_PRIORITY_VPN_OUTPUT_TO_LOCAL = 11000; 42const uint32_t RULE_PRIORITY_SECURE_VPN = 12000; 43const uint32_t RULE_PRIORITY_EXPLICIT_NETWORK = 13000; 44const uint32_t RULE_PRIORITY_OUTPUT_INTERFACE = 14000; 45const uint32_t RULE_PRIORITY_LEGACY_SYSTEM = 15000; 46const uint32_t RULE_PRIORITY_LEGACY_NETWORK = 16000; 47const uint32_t RULE_PRIORITY_LOCAL_NETWORK = 17000; 48const uint32_t RULE_PRIORITY_TETHERING = 18000; 49const uint32_t RULE_PRIORITY_IMPLICIT_NETWORK = 19000; 50const uint32_t RULE_PRIORITY_BYPASSABLE_VPN = 20000; 51const uint32_t RULE_PRIORITY_VPN_FALLTHROUGH = 21000; 52const uint32_t RULE_PRIORITY_DEFAULT_NETWORK = 22000; 53const uint32_t RULE_PRIORITY_DIRECTLY_CONNECTED = 23000; 54const uint32_t RULE_PRIORITY_UNREACHABLE = 32000; 55 56const uint32_t ROUTE_TABLE_LOCAL_NETWORK = 97; 57const uint32_t ROUTE_TABLE_LEGACY_NETWORK = 98; 58const uint32_t ROUTE_TABLE_LEGACY_SYSTEM = 99; 59 60const char* const ROUTE_TABLE_NAME_LOCAL_NETWORK = "local_network"; 61const char* const ROUTE_TABLE_NAME_LEGACY_NETWORK = "legacy_network"; 62const char* const ROUTE_TABLE_NAME_LEGACY_SYSTEM = "legacy_system"; 63 64const char* const ROUTE_TABLE_NAME_LOCAL = "local"; 65const char* const ROUTE_TABLE_NAME_MAIN = "main"; 66 67// TODO: These values aren't defined by the Linux kernel, because our UID routing changes are not 68// upstream (yet?), so we can't just pick them up from kernel headers. When (if?) the changes make 69// it upstream, we'll remove this and rely on the kernel header values. For now, add a static assert 70// that will warn us if upstream has given these values some other meaning. 71const uint16_t FRA_UID_START = 18; 72const uint16_t FRA_UID_END = 19; 73static_assert(FRA_UID_START > FRA_MAX, 74 "Android-specific FRA_UID_{START,END} values also assigned in Linux uapi. " 75 "Check that these values match what the kernel does and then update this assertion."); 76 77const uint16_t NETLINK_REQUEST_FLAGS = NLM_F_REQUEST | NLM_F_ACK; 78const uint16_t NETLINK_CREATE_REQUEST_FLAGS = NETLINK_REQUEST_FLAGS | NLM_F_CREATE | NLM_F_EXCL; 79 80const sockaddr_nl NETLINK_ADDRESS = {AF_NETLINK, 0, 0, 0}; 81 82const uint8_t AF_FAMILIES[] = {AF_INET, AF_INET6}; 83 84const char* const IP_VERSIONS[] = {"-4", "-6"}; 85 86const uid_t UID_ROOT = 0; 87const char* const IIF_LOOPBACK = "lo"; 88const char* const IIF_NONE = NULL; 89const char* const OIF_NONE = NULL; 90const bool ACTION_ADD = true; 91const bool ACTION_DEL = false; 92const bool MODIFY_NON_UID_BASED_RULES = true; 93 94const char* const RT_TABLES_PATH = "/data/misc/net/rt_tables"; 95const int RT_TABLES_FLAGS = O_CREAT | O_TRUNC | O_WRONLY | O_NOFOLLOW | O_CLOEXEC; 96const mode_t RT_TABLES_MODE = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH; // mode 0644, rw-r--r-- 97 98const unsigned ROUTE_FLUSH_ATTEMPTS = 2; 99 100// Avoids "non-constant-expression cannot be narrowed from type 'unsigned int' to 'unsigned short'" 101// warnings when using RTA_LENGTH(x) inside static initializers (even when x is already uint16_t). 102constexpr uint16_t U16_RTA_LENGTH(uint16_t x) { 103 return RTA_LENGTH(x); 104} 105 106// These are practically const, but can't be declared so, because they are used to initialize 107// non-const pointers ("void* iov_base") in iovec arrays. 108rtattr FRATTR_PRIORITY = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_PRIORITY }; 109rtattr FRATTR_TABLE = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_TABLE }; 110rtattr FRATTR_FWMARK = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_FWMARK }; 111rtattr FRATTR_FWMASK = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_FWMASK }; 112rtattr FRATTR_UID_START = { U16_RTA_LENGTH(sizeof(uid_t)), FRA_UID_START }; 113rtattr FRATTR_UID_END = { U16_RTA_LENGTH(sizeof(uid_t)), FRA_UID_END }; 114 115rtattr RTATTR_TABLE = { U16_RTA_LENGTH(sizeof(uint32_t)), RTA_TABLE }; 116rtattr RTATTR_OIF = { U16_RTA_LENGTH(sizeof(uint32_t)), RTA_OIF }; 117 118uint8_t PADDING_BUFFER[RTA_ALIGNTO] = {0, 0, 0, 0}; 119 120// END CONSTANTS ---------------------------------------------------------------------------------- 121 122// No locks needed because RouteController is accessed only from one thread (in CommandListener). 123std::map<std::string, uint32_t> interfaceToTable; 124 125uint32_t getRouteTableForInterface(const char* interface) { 126 uint32_t index = if_nametoindex(interface); 127 if (index) { 128 index += RouteController::ROUTE_TABLE_OFFSET_FROM_INDEX; 129 interfaceToTable[interface] = index; 130 return index; 131 } 132 // If the interface goes away if_nametoindex() will return 0 but we still need to know 133 // the index so we can remove the rules and routes. 134 auto iter = interfaceToTable.find(interface); 135 if (iter == interfaceToTable.end()) { 136 ALOGE("cannot find interface %s", interface); 137 return RT_TABLE_UNSPEC; 138 } 139 return iter->second; 140} 141 142void addTableName(uint32_t table, const std::string& name, std::string* contents) { 143 char tableString[UINT32_STRLEN]; 144 snprintf(tableString, sizeof(tableString), "%u", table); 145 *contents += tableString; 146 *contents += " "; 147 *contents += name; 148 *contents += "\n"; 149} 150 151// Doesn't return success/failure as the file is optional; it's okay if we fail to update it. 152void updateTableNamesFile() { 153 std::string contents; 154 155 addTableName(RT_TABLE_LOCAL, ROUTE_TABLE_NAME_LOCAL, &contents); 156 addTableName(RT_TABLE_MAIN, ROUTE_TABLE_NAME_MAIN, &contents); 157 158 addTableName(ROUTE_TABLE_LOCAL_NETWORK, ROUTE_TABLE_NAME_LOCAL_NETWORK, &contents); 159 addTableName(ROUTE_TABLE_LEGACY_NETWORK, ROUTE_TABLE_NAME_LEGACY_NETWORK, &contents); 160 addTableName(ROUTE_TABLE_LEGACY_SYSTEM, ROUTE_TABLE_NAME_LEGACY_SYSTEM, &contents); 161 162 for (const auto& entry : interfaceToTable) { 163 addTableName(entry.second, entry.first, &contents); 164 } 165 166 int fd = open(RT_TABLES_PATH, RT_TABLES_FLAGS, RT_TABLES_MODE); 167 if (fd == -1) { 168 ALOGE("failed to create %s (%s)", RT_TABLES_PATH, strerror(errno)); 169 return; 170 } 171 // File creation is affected by umask, so make sure the right mode bits are set. 172 if (fchmod(fd, RT_TABLES_MODE) == -1) { 173 ALOGE("failed to set mode 0%o on %s (%s)", RT_TABLES_MODE, RT_TABLES_PATH, strerror(errno)); 174 } 175 ssize_t bytesWritten = write(fd, contents.data(), contents.size()); 176 if (bytesWritten != static_cast<ssize_t>(contents.size())) { 177 ALOGE("failed to write to %s (%zd vs %zu bytes) (%s)", RT_TABLES_PATH, bytesWritten, 178 contents.size(), strerror(errno)); 179 } 180 close(fd); 181} 182 183// Sends a netlink request and expects an ack. 184// |iov| is an array of struct iovec that contains the netlink message payload. 185// The netlink header is generated by this function based on |action| and |flags|. 186// Returns -errno if there was an error or if the kernel reported an error. 187WARN_UNUSED_RESULT int sendNetlinkRequest(uint16_t action, uint16_t flags, iovec* iov, int iovlen) { 188 nlmsghdr nlmsg = { 189 .nlmsg_type = action, 190 .nlmsg_flags = flags, 191 }; 192 iov[0].iov_base = &nlmsg; 193 iov[0].iov_len = sizeof(nlmsg); 194 for (int i = 0; i < iovlen; ++i) { 195 nlmsg.nlmsg_len += iov[i].iov_len; 196 } 197 198 int ret; 199 struct { 200 nlmsghdr msg; 201 nlmsgerr err; 202 } response; 203 204 int sock = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE); 205 if (sock != -1 && 206 connect(sock, reinterpret_cast<const sockaddr*>(&NETLINK_ADDRESS), 207 sizeof(NETLINK_ADDRESS)) != -1 && 208 writev(sock, iov, iovlen) != -1 && 209 (ret = recv(sock, &response, sizeof(response), 0)) != -1) { 210 if (ret == sizeof(response)) { 211 ret = response.err.error; // Netlink errors are negative errno. 212 if (ret) { 213 ALOGE("netlink response contains error (%s)", strerror(-ret)); 214 } 215 } else { 216 ALOGE("bad netlink response message size (%d != %zu)", ret, sizeof(response)); 217 ret = -EBADMSG; 218 } 219 } else { 220 ALOGE("netlink socket/connect/writev/recv failed (%s)", strerror(errno)); 221 ret = -errno; 222 } 223 224 if (sock != -1) { 225 close(sock); 226 } 227 228 return ret; 229} 230 231// Returns 0 on success or negative errno on failure. 232int padInterfaceName(const char* input, char* name, size_t* length, uint16_t* padding) { 233 if (!input) { 234 *length = 0; 235 *padding = 0; 236 return 0; 237 } 238 *length = strlcpy(name, input, IFNAMSIZ) + 1; 239 if (*length > IFNAMSIZ) { 240 ALOGE("interface name too long (%zu > %u)", *length, IFNAMSIZ); 241 return -ENAMETOOLONG; 242 } 243 *padding = RTA_SPACE(*length) - RTA_LENGTH(*length); 244 return 0; 245} 246 247// Adds or removes a routing rule for IPv4 and IPv6. 248// 249// + If |table| is non-zero, the rule points at the specified routing table. Otherwise, the rule 250// returns ENETUNREACH. 251// + If |mask| is non-zero, the rule matches the specified fwmark and mask. Otherwise, |fwmark| is 252// ignored. 253// + If |iif| is non-NULL, the rule matches the specified incoming interface. 254// + If |oif| is non-NULL, the rule matches the specified outgoing interface. 255// + If |uidStart| and |uidEnd| are not INVALID_UID, the rule matches packets from UIDs in that 256// range (inclusive). Otherwise, the rule matches packets from all UIDs. 257// 258// Returns 0 on success or negative errno on failure. 259WARN_UNUSED_RESULT int modifyIpRule(uint16_t action, uint32_t priority, uint32_t table, 260 uint32_t fwmark, uint32_t mask, const char* iif, 261 const char* oif, uid_t uidStart, uid_t uidEnd) { 262 // Ensure that if you set a bit in the fwmark, it's not being ignored by the mask. 263 if (fwmark & ~mask) { 264 ALOGE("mask 0x%x does not select all the bits set in fwmark 0x%x", mask, fwmark); 265 return -ERANGE; 266 } 267 268 // Interface names must include exactly one terminating NULL and be properly padded, or older 269 // kernels will refuse to delete rules. 270 char iifName[IFNAMSIZ], oifName[IFNAMSIZ]; 271 size_t iifLength, oifLength; 272 uint16_t iifPadding, oifPadding; 273 if (int ret = padInterfaceName(iif, iifName, &iifLength, &iifPadding)) { 274 return ret; 275 } 276 if (int ret = padInterfaceName(oif, oifName, &oifLength, &oifPadding)) { 277 return ret; 278 } 279 280 // Either both start and end UID must be specified, or neither. 281 if ((uidStart == INVALID_UID) != (uidEnd == INVALID_UID)) { 282 ALOGE("incompatible start and end UIDs (%u vs %u)", uidStart, uidEnd); 283 return -EUSERS; 284 } 285 bool isUidRule = (uidStart != INVALID_UID); 286 287 // Assemble a rule request and put it in an array of iovec structures. 288 fib_rule_hdr rule = { 289 .action = static_cast<uint8_t>(table != RT_TABLE_UNSPEC ? FR_ACT_TO_TBL : 290 FR_ACT_UNREACHABLE), 291 }; 292 293 rtattr fraIifName = { U16_RTA_LENGTH(iifLength), FRA_IIFNAME }; 294 rtattr fraOifName = { U16_RTA_LENGTH(oifLength), FRA_OIFNAME }; 295 296 iovec iov[] = { 297 { NULL, 0 }, 298 { &rule, sizeof(rule) }, 299 { &FRATTR_PRIORITY, sizeof(FRATTR_PRIORITY) }, 300 { &priority, sizeof(priority) }, 301 { &FRATTR_TABLE, table != RT_TABLE_UNSPEC ? sizeof(FRATTR_TABLE) : 0 }, 302 { &table, table != RT_TABLE_UNSPEC ? sizeof(table) : 0 }, 303 { &FRATTR_FWMARK, mask ? sizeof(FRATTR_FWMARK) : 0 }, 304 { &fwmark, mask ? sizeof(fwmark) : 0 }, 305 { &FRATTR_FWMASK, mask ? sizeof(FRATTR_FWMASK) : 0 }, 306 { &mask, mask ? sizeof(mask) : 0 }, 307 { &FRATTR_UID_START, isUidRule ? sizeof(FRATTR_UID_START) : 0 }, 308 { &uidStart, isUidRule ? sizeof(uidStart) : 0 }, 309 { &FRATTR_UID_END, isUidRule ? sizeof(FRATTR_UID_END) : 0 }, 310 { &uidEnd, isUidRule ? sizeof(uidEnd) : 0 }, 311 { &fraIifName, iif != IIF_NONE ? sizeof(fraIifName) : 0 }, 312 { iifName, iifLength }, 313 { PADDING_BUFFER, iifPadding }, 314 { &fraOifName, oif != OIF_NONE ? sizeof(fraOifName) : 0 }, 315 { oifName, oifLength }, 316 { PADDING_BUFFER, oifPadding }, 317 }; 318 319 uint16_t flags = (action == RTM_NEWRULE) ? NETLINK_CREATE_REQUEST_FLAGS : NETLINK_REQUEST_FLAGS; 320 for (size_t i = 0; i < ARRAY_SIZE(AF_FAMILIES); ++i) { 321 rule.family = AF_FAMILIES[i]; 322 if (int ret = sendNetlinkRequest(action, flags, iov, ARRAY_SIZE(iov))) { 323 return ret; 324 } 325 } 326 327 return 0; 328} 329 330WARN_UNUSED_RESULT int modifyIpRule(uint16_t action, uint32_t priority, uint32_t table, 331 uint32_t fwmark, uint32_t mask) { 332 return modifyIpRule(action, priority, table, fwmark, mask, IIF_NONE, OIF_NONE, INVALID_UID, 333 INVALID_UID); 334} 335 336// Adds or deletes an IPv4 or IPv6 route. 337// Returns 0 on success or negative errno on failure. 338WARN_UNUSED_RESULT int modifyIpRoute(uint16_t action, uint32_t table, const char* interface, 339 const char* destination, const char* nexthop) { 340 // At least the destination must be non-null. 341 if (!destination) { 342 ALOGE("null destination"); 343 return -EFAULT; 344 } 345 346 // Parse the prefix. 347 uint8_t rawAddress[sizeof(in6_addr)]; 348 uint8_t family; 349 uint8_t prefixLength; 350 int rawLength = parsePrefix(destination, &family, rawAddress, sizeof(rawAddress), 351 &prefixLength); 352 if (rawLength < 0) { 353 ALOGE("parsePrefix failed for destination %s (%s)", destination, strerror(-rawLength)); 354 return rawLength; 355 } 356 357 if (static_cast<size_t>(rawLength) > sizeof(rawAddress)) { 358 ALOGE("impossible! address too long (%d vs %zu)", rawLength, sizeof(rawAddress)); 359 return -ENOBUFS; // Cannot happen; parsePrefix only supports IPv4 and IPv6. 360 } 361 362 uint8_t type = RTN_UNICAST; 363 uint32_t ifindex; 364 uint8_t rawNexthop[sizeof(in6_addr)]; 365 366 if (nexthop && !strcmp(nexthop, "unreachable")) { 367 type = RTN_UNREACHABLE; 368 // 'interface' is likely non-NULL, as the caller (modifyRoute()) likely used it to lookup 369 // the table number. But it's an error to specify an interface ("dev ...") or a nexthop for 370 // unreachable routes, so nuke them. (IPv6 allows them to be specified; IPv4 doesn't.) 371 interface = OIF_NONE; 372 nexthop = NULL; 373 } else if (nexthop && !strcmp(nexthop, "throw")) { 374 type = RTN_THROW; 375 interface = OIF_NONE; 376 nexthop = NULL; 377 } else { 378 // If an interface was specified, find the ifindex. 379 if (interface != OIF_NONE) { 380 ifindex = if_nametoindex(interface); 381 if (!ifindex) { 382 ALOGE("cannot find interface %s", interface); 383 return -ENODEV; 384 } 385 } 386 387 // If a nexthop was specified, parse it as the same family as the prefix. 388 if (nexthop && inet_pton(family, nexthop, rawNexthop) <= 0) { 389 ALOGE("inet_pton failed for nexthop %s", nexthop); 390 return -EINVAL; 391 } 392 } 393 394 // Assemble a rtmsg and put it in an array of iovec structures. 395 rtmsg route = { 396 .rtm_protocol = RTPROT_STATIC, 397 .rtm_type = type, 398 .rtm_family = family, 399 .rtm_dst_len = prefixLength, 400 .rtm_scope = static_cast<uint8_t>(nexthop ? RT_SCOPE_UNIVERSE : RT_SCOPE_LINK), 401 }; 402 403 rtattr rtaDst = { U16_RTA_LENGTH(rawLength), RTA_DST }; 404 rtattr rtaGateway = { U16_RTA_LENGTH(rawLength), RTA_GATEWAY }; 405 406 iovec iov[] = { 407 { NULL, 0 }, 408 { &route, sizeof(route) }, 409 { &RTATTR_TABLE, sizeof(RTATTR_TABLE) }, 410 { &table, sizeof(table) }, 411 { &rtaDst, sizeof(rtaDst) }, 412 { rawAddress, static_cast<size_t>(rawLength) }, 413 { &RTATTR_OIF, interface != OIF_NONE ? sizeof(RTATTR_OIF) : 0 }, 414 { &ifindex, interface != OIF_NONE ? sizeof(ifindex) : 0 }, 415 { &rtaGateway, nexthop ? sizeof(rtaGateway) : 0 }, 416 { rawNexthop, nexthop ? static_cast<size_t>(rawLength) : 0 }, 417 }; 418 419 uint16_t flags = (action == RTM_NEWROUTE) ? NETLINK_CREATE_REQUEST_FLAGS : 420 NETLINK_REQUEST_FLAGS; 421 return sendNetlinkRequest(action, flags, iov, ARRAY_SIZE(iov)); 422} 423 424// An iptables rule to mark incoming packets on a network with the netId of the network. 425// 426// This is so that the kernel can: 427// + Use the right fwmark for (and thus correctly route) replies (e.g.: TCP RST, ICMP errors, ping 428// replies, SYN-ACKs, etc). 429// + Mark sockets that accept connections from this interface so that the connection stays on the 430// same interface. 431WARN_UNUSED_RESULT int modifyIncomingPacketMark(unsigned netId, const char* interface, 432 Permission permission, bool add) { 433 Fwmark fwmark; 434 435 fwmark.netId = netId; 436 fwmark.explicitlySelected = true; 437 fwmark.protectedFromVpn = true; 438 fwmark.permission = permission; 439 440 char markString[UINT32_HEX_STRLEN]; 441 snprintf(markString, sizeof(markString), "0x%x", fwmark.intValue); 442 443 if (execIptables(V4V6, "-t", "mangle", add ? "-A" : "-D", "INPUT", "-i", interface, "-j", 444 "MARK", "--set-mark", markString, NULL)) { 445 ALOGE("failed to change iptables rule that sets incoming packet mark"); 446 return -EREMOTEIO; 447 } 448 449 return 0; 450} 451 452// A rule to route responses to the local network forwarded via the VPN. 453// 454// When a VPN is in effect, packets from the local network to upstream networks are forwarded into 455// the VPN's tunnel interface. When the VPN forwards the responses, they emerge out of the tunnel. 456WARN_UNUSED_RESULT int modifyVpnOutputToLocalRule(const char* vpnInterface, bool add) { 457 return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_VPN_OUTPUT_TO_LOCAL, 458 ROUTE_TABLE_LOCAL_NETWORK, MARK_UNSET, MARK_UNSET, vpnInterface, OIF_NONE, 459 INVALID_UID, INVALID_UID); 460} 461 462// A rule to route all traffic from a given set of UIDs to go over the VPN. 463// 464// Notice that this rule doesn't use the netId. I.e., no matter what netId the user's socket may 465// have, if they are subject to this VPN, their traffic has to go through it. Allows the traffic to 466// bypass the VPN if the protectedFromVpn bit is set. 467WARN_UNUSED_RESULT int modifyVpnUidRangeRule(uint32_t table, uid_t uidStart, uid_t uidEnd, 468 bool secure, bool add) { 469 Fwmark fwmark; 470 Fwmark mask; 471 472 fwmark.protectedFromVpn = false; 473 mask.protectedFromVpn = true; 474 475 uint32_t priority; 476 477 if (secure) { 478 priority = RULE_PRIORITY_SECURE_VPN; 479 } else { 480 priority = RULE_PRIORITY_BYPASSABLE_VPN; 481 482 fwmark.explicitlySelected = false; 483 mask.explicitlySelected = true; 484 } 485 486 return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, priority, table, fwmark.intValue, 487 mask.intValue, IIF_LOOPBACK, OIF_NONE, uidStart, uidEnd); 488} 489 490// A rule to allow system apps to send traffic over this VPN even if they are not part of the target 491// set of UIDs. 492// 493// This is needed for DnsProxyListener to correctly resolve a request for a user who is in the 494// target set, but where the DnsProxyListener itself is not. 495WARN_UNUSED_RESULT int modifyVpnSystemPermissionRule(unsigned netId, uint32_t table, bool secure, 496 bool add) { 497 Fwmark fwmark; 498 Fwmark mask; 499 500 fwmark.netId = netId; 501 mask.netId = FWMARK_NET_ID_MASK; 502 503 fwmark.permission = PERMISSION_SYSTEM; 504 mask.permission = PERMISSION_SYSTEM; 505 506 uint32_t priority = secure ? RULE_PRIORITY_SECURE_VPN : RULE_PRIORITY_BYPASSABLE_VPN; 507 508 return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, priority, table, fwmark.intValue, 509 mask.intValue); 510} 511 512// A rule to route traffic based on an explicitly chosen network. 513// 514// Supports apps that use the multinetwork APIs to restrict their traffic to a network. 515// 516// Even though we check permissions at the time we set a netId into the fwmark of a socket, we need 517// to check it again in the rules here, because a network's permissions may have been updated via 518// modifyNetworkPermission(). 519WARN_UNUSED_RESULT int modifyExplicitNetworkRule(unsigned netId, uint32_t table, 520 Permission permission, uid_t uidStart, 521 uid_t uidEnd, bool add) { 522 Fwmark fwmark; 523 Fwmark mask; 524 525 fwmark.netId = netId; 526 mask.netId = FWMARK_NET_ID_MASK; 527 528 fwmark.explicitlySelected = true; 529 mask.explicitlySelected = true; 530 531 fwmark.permission = permission; 532 mask.permission = permission; 533 534 return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_EXPLICIT_NETWORK, table, 535 fwmark.intValue, mask.intValue, IIF_NONE, OIF_NONE, uidStart, uidEnd); 536} 537 538// A rule to route traffic based on a chosen outgoing interface. 539// 540// Supports apps that use SO_BINDTODEVICE or IP_PKTINFO options and the kernel that already knows 541// the outgoing interface (typically for link-local communications). 542WARN_UNUSED_RESULT int modifyOutputInterfaceRule(const char* interface, uint32_t table, 543 Permission permission, uid_t uidStart, 544 uid_t uidEnd, bool add) { 545 Fwmark fwmark; 546 Fwmark mask; 547 548 fwmark.permission = permission; 549 mask.permission = permission; 550 551 return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_OUTPUT_INTERFACE, table, 552 fwmark.intValue, mask.intValue, IIF_NONE, interface, uidStart, uidEnd); 553} 554 555// A rule to route traffic based on the chosen network. 556// 557// This is for sockets that have not explicitly requested a particular network, but have been 558// bound to one when they called connect(). This ensures that sockets connected on a particular 559// network stay on that network even if the default network changes. 560WARN_UNUSED_RESULT int modifyImplicitNetworkRule(unsigned netId, uint32_t table, 561 Permission permission, bool add) { 562 Fwmark fwmark; 563 Fwmark mask; 564 565 fwmark.netId = netId; 566 mask.netId = FWMARK_NET_ID_MASK; 567 568 fwmark.explicitlySelected = false; 569 mask.explicitlySelected = true; 570 571 fwmark.permission = permission; 572 mask.permission = permission; 573 574 return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_IMPLICIT_NETWORK, table, 575 fwmark.intValue, mask.intValue); 576} 577 578// A rule to enable split tunnel VPNs. 579// 580// If a packet with a VPN's netId doesn't find a route in the VPN's routing table, it's allowed to 581// go over the default network, provided it wasn't explicitly restricted to the VPN and has the 582// permissions required by the default network. 583WARN_UNUSED_RESULT int modifyVpnFallthroughRule(uint16_t action, unsigned vpnNetId, 584 const char* physicalInterface, 585 Permission permission) { 586 uint32_t table = getRouteTableForInterface(physicalInterface); 587 if (table == RT_TABLE_UNSPEC) { 588 return -ESRCH; 589 } 590 591 Fwmark fwmark; 592 Fwmark mask; 593 594 fwmark.netId = vpnNetId; 595 mask.netId = FWMARK_NET_ID_MASK; 596 597 fwmark.explicitlySelected = false; 598 mask.explicitlySelected = true; 599 600 fwmark.permission = permission; 601 mask.permission = permission; 602 603 return modifyIpRule(action, RULE_PRIORITY_VPN_FALLTHROUGH, table, fwmark.intValue, 604 mask.intValue); 605} 606 607// Add rules to allow legacy routes added through the requestRouteToHost() API. 608WARN_UNUSED_RESULT int addLegacyRouteRules() { 609 Fwmark fwmark; 610 Fwmark mask; 611 612 fwmark.explicitlySelected = false; 613 mask.explicitlySelected = true; 614 615 // Rules to allow legacy routes to override the default network. 616 if (int ret = modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_LEGACY_SYSTEM, ROUTE_TABLE_LEGACY_SYSTEM, 617 fwmark.intValue, mask.intValue)) { 618 return ret; 619 } 620 if (int ret = modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_LEGACY_NETWORK, 621 ROUTE_TABLE_LEGACY_NETWORK, fwmark.intValue, mask.intValue)) { 622 return ret; 623 } 624 625 fwmark.permission = PERMISSION_SYSTEM; 626 mask.permission = PERMISSION_SYSTEM; 627 628 // A rule to allow legacy routes from system apps to override VPNs. 629 return modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_VPN_OVERRIDE_SYSTEM, ROUTE_TABLE_LEGACY_SYSTEM, 630 fwmark.intValue, mask.intValue); 631} 632 633// Add rules to lookup the local network when specified explicitly or otherwise. 634WARN_UNUSED_RESULT int addLocalNetworkRules(unsigned localNetId) { 635 if (int ret = modifyExplicitNetworkRule(localNetId, ROUTE_TABLE_LOCAL_NETWORK, PERMISSION_NONE, 636 INVALID_UID, INVALID_UID, ACTION_ADD)) { 637 return ret; 638 } 639 640 Fwmark fwmark; 641 Fwmark mask; 642 643 fwmark.explicitlySelected = false; 644 mask.explicitlySelected = true; 645 646 return modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_LOCAL_NETWORK, ROUTE_TABLE_LOCAL_NETWORK, 647 fwmark.intValue, mask.intValue); 648} 649 650int configureDummyNetwork() { 651 const char *interface = DummyNetwork::INTERFACE_NAME; 652 uint32_t table = getRouteTableForInterface(interface); 653 if (table == RT_TABLE_UNSPEC) { 654 // getRouteTableForInterface has already looged an error. 655 return -ESRCH; 656 } 657 658 ifc_init(); 659 int ret = ifc_up(interface); 660 ifc_close(); 661 if (ret) { 662 ALOGE("Can't bring up %s: %s", interface, strerror(errno)); 663 return -errno; 664 } 665 666 if ((ret = modifyOutputInterfaceRule(interface, table, PERMISSION_NONE, 667 INVALID_UID, INVALID_UID, ACTION_ADD))) { 668 ALOGE("Can't create oif rule for %s: %s", interface, strerror(-ret)); 669 return ret; 670 } 671 672 if ((ret = modifyIpRoute(RTM_NEWROUTE, table, interface, "0.0.0.0/0", NULL))) { 673 ALOGE("Can't add IPv4 default route to %s: %s", interface, strerror(-ret)); 674 return ret; 675 } 676 677 if ((ret = modifyIpRoute(RTM_NEWROUTE, table, interface, "::/0", NULL))) { 678 ALOGE("Can't add IPv6 default route to %s: %s", interface, strerror(-ret)); 679 return ret; 680 } 681 682 return 0; 683} 684 685// Add a new rule to look up the 'main' table, with the same selectors as the "default network" 686// rule, but with a lower priority. We will never create routes in the main table; it should only be 687// used for directly-connected routes implicitly created by the kernel when adding IP addresses. 688// This is necessary, for example, when adding a route through a directly-connected gateway: in 689// order to add the route, there must already be a directly-connected route that covers the gateway. 690WARN_UNUSED_RESULT int addDirectlyConnectedRule() { 691 Fwmark fwmark; 692 Fwmark mask; 693 694 fwmark.netId = NETID_UNSET; 695 mask.netId = FWMARK_NET_ID_MASK; 696 697 return modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_DIRECTLY_CONNECTED, RT_TABLE_MAIN, 698 fwmark.intValue, mask.intValue, IIF_NONE, OIF_NONE, UID_ROOT, UID_ROOT); 699} 700 701// Add an explicit unreachable rule close to the end of the prioriy list to make it clear that 702// relying on the kernel-default "from all lookup main" rule at priority 32766 is not intended 703// behaviour. We do flush the kernel-default rules at startup, but having an explicit unreachable 704// rule will hopefully make things even clearer. 705WARN_UNUSED_RESULT int addUnreachableRule() { 706 return modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_UNREACHABLE, RT_TABLE_UNSPEC, MARK_UNSET, 707 MARK_UNSET); 708} 709 710WARN_UNUSED_RESULT int modifyLocalNetwork(unsigned netId, const char* interface, bool add) { 711 if (int ret = modifyIncomingPacketMark(netId, interface, PERMISSION_NONE, add)) { 712 return ret; 713 } 714 return modifyOutputInterfaceRule(interface, ROUTE_TABLE_LOCAL_NETWORK, PERMISSION_NONE, 715 INVALID_UID, INVALID_UID, add); 716} 717 718WARN_UNUSED_RESULT int modifyPhysicalNetwork(unsigned netId, const char* interface, 719 Permission permission, bool add) { 720 uint32_t table = getRouteTableForInterface(interface); 721 if (table == RT_TABLE_UNSPEC) { 722 return -ESRCH; 723 } 724 725 if (int ret = modifyIncomingPacketMark(netId, interface, permission, add)) { 726 return ret; 727 } 728 if (int ret = modifyExplicitNetworkRule(netId, table, permission, INVALID_UID, INVALID_UID, 729 add)) { 730 return ret; 731 } 732 if (int ret = modifyOutputInterfaceRule(interface, table, permission, INVALID_UID, INVALID_UID, 733 add)) { 734 return ret; 735 } 736 return modifyImplicitNetworkRule(netId, table, permission, add); 737} 738 739WARN_UNUSED_RESULT int modifyVirtualNetwork(unsigned netId, const char* interface, 740 const UidRanges& uidRanges, bool secure, bool add, 741 bool modifyNonUidBasedRules) { 742 uint32_t table = getRouteTableForInterface(interface); 743 if (table == RT_TABLE_UNSPEC) { 744 return -ESRCH; 745 } 746 747 for (const UidRanges::Range& range : uidRanges.getRanges()) { 748 if (int ret = modifyVpnUidRangeRule(table, range.first, range.second, secure, add)) { 749 return ret; 750 } 751 if (int ret = modifyExplicitNetworkRule(netId, table, PERMISSION_NONE, range.first, 752 range.second, add)) { 753 return ret; 754 } 755 if (int ret = modifyOutputInterfaceRule(interface, table, PERMISSION_NONE, range.first, 756 range.second, add)) { 757 return ret; 758 } 759 } 760 761 if (modifyNonUidBasedRules) { 762 if (int ret = modifyIncomingPacketMark(netId, interface, PERMISSION_NONE, add)) { 763 return ret; 764 } 765 if (int ret = modifyVpnOutputToLocalRule(interface, add)) { 766 return ret; 767 } 768 if (int ret = modifyVpnSystemPermissionRule(netId, table, secure, add)) { 769 return ret; 770 } 771 return modifyExplicitNetworkRule(netId, table, PERMISSION_NONE, UID_ROOT, UID_ROOT, add); 772 } 773 774 return 0; 775} 776 777WARN_UNUSED_RESULT int modifyDefaultNetwork(uint16_t action, const char* interface, 778 Permission permission) { 779 uint32_t table = getRouteTableForInterface(interface); 780 if (table == RT_TABLE_UNSPEC) { 781 return -ESRCH; 782 } 783 784 Fwmark fwmark; 785 Fwmark mask; 786 787 fwmark.netId = NETID_UNSET; 788 mask.netId = FWMARK_NET_ID_MASK; 789 790 fwmark.permission = permission; 791 mask.permission = permission; 792 793 return modifyIpRule(action, RULE_PRIORITY_DEFAULT_NETWORK, table, fwmark.intValue, 794 mask.intValue); 795} 796 797WARN_UNUSED_RESULT int modifyTetheredNetwork(uint16_t action, const char* inputInterface, 798 const char* outputInterface) { 799 uint32_t table = getRouteTableForInterface(outputInterface); 800 if (table == RT_TABLE_UNSPEC) { 801 return -ESRCH; 802 } 803 804 return modifyIpRule(action, RULE_PRIORITY_TETHERING, table, MARK_UNSET, MARK_UNSET, 805 inputInterface, OIF_NONE, INVALID_UID, INVALID_UID); 806} 807 808// Returns 0 on success or negative errno on failure. 809WARN_UNUSED_RESULT int flushRules() { 810 for (size_t i = 0; i < ARRAY_SIZE(IP_VERSIONS); ++i) { 811 const char* argv[] = { 812 IP_PATH, 813 IP_VERSIONS[i], 814 "rule", 815 "flush", 816 }; 817 if (android_fork_execvp(ARRAY_SIZE(argv), const_cast<char**>(argv), NULL, false, false)) { 818 ALOGE("failed to flush rules"); 819 return -EREMOTEIO; 820 } 821 } 822 return 0; 823} 824 825// Adds or removes an IPv4 or IPv6 route to the specified table and, if it's a directly-connected 826// route, to the main table as well. 827// Returns 0 on success or negative errno on failure. 828WARN_UNUSED_RESULT int modifyRoute(uint16_t action, const char* interface, const char* destination, 829 const char* nexthop, RouteController::TableType tableType) { 830 uint32_t table; 831 switch (tableType) { 832 case RouteController::INTERFACE: { 833 table = getRouteTableForInterface(interface); 834 if (table == RT_TABLE_UNSPEC) { 835 return -ESRCH; 836 } 837 break; 838 } 839 case RouteController::LOCAL_NETWORK: { 840 table = ROUTE_TABLE_LOCAL_NETWORK; 841 break; 842 } 843 case RouteController::LEGACY_NETWORK: { 844 table = ROUTE_TABLE_LEGACY_NETWORK; 845 break; 846 } 847 case RouteController::LEGACY_SYSTEM: { 848 table = ROUTE_TABLE_LEGACY_SYSTEM; 849 break; 850 } 851 } 852 853 int ret = modifyIpRoute(action, table, interface, destination, nexthop); 854 // Trying to add a route that already exists shouldn't cause an error. 855 if (ret && !(action == RTM_NEWROUTE && ret == -EEXIST)) { 856 return ret; 857 } 858 859 return 0; 860} 861 862// Returns 0 on success or negative errno on failure. 863WARN_UNUSED_RESULT int flushRoutes(const char* interface) { 864 uint32_t table = getRouteTableForInterface(interface); 865 if (table == RT_TABLE_UNSPEC) { 866 return -ESRCH; 867 } 868 869 char tableString[UINT32_STRLEN]; 870 snprintf(tableString, sizeof(tableString), "%u", table); 871 872 int ret = 0; 873 for (size_t i = 0; i < ARRAY_SIZE(IP_VERSIONS); ++i) { 874 const char* argv[] = { 875 IP_PATH, 876 IP_VERSIONS[i], 877 "route", 878 "flush", 879 "table", 880 tableString, 881 }; 882 883 // A flush works by dumping routes and deleting each route as it's returned, and it can 884 // fail if something else deletes the route between the dump and the delete. This can 885 // happen, for example, if an interface goes down while we're trying to flush its routes. 886 // So try multiple times and only return an error if the last attempt fails. 887 // 888 // TODO: replace this with our own netlink code. 889 unsigned attempts = 0; 890 int err; 891 do { 892 err = android_fork_execvp(ARRAY_SIZE(argv), const_cast<char**>(argv), 893 NULL, false, false); 894 ++attempts; 895 } while (err != 0 && attempts < ROUTE_FLUSH_ATTEMPTS); 896 if (err) { 897 ALOGE("failed to flush %s routes in table %s after %d attempts", 898 IP_VERSIONS[i], tableString, attempts); 899 ret = -EREMOTEIO; 900 } 901 } 902 903 // If we failed to flush routes, the caller may elect to keep this interface around, so keep 904 // track of its name. 905 if (!ret) { 906 interfaceToTable.erase(interface); 907 } 908 909 return ret; 910} 911 912} // namespace 913 914int RouteController::Init(unsigned localNetId) { 915 if (int ret = flushRules()) { 916 return ret; 917 } 918 if (int ret = addLegacyRouteRules()) { 919 return ret; 920 } 921 if (int ret = addLocalNetworkRules(localNetId)) { 922 return ret; 923 } 924 if (int ret = addDirectlyConnectedRule()) { 925 return ret; 926 } 927 if (int ret = addUnreachableRule()) { 928 return ret; 929 } 930 // Don't complain if we can't add the dummy network, since not all devices support it. 931 configureDummyNetwork(); 932 933 updateTableNamesFile(); 934 return 0; 935} 936 937int RouteController::addInterfaceToLocalNetwork(unsigned netId, const char* interface) { 938 return modifyLocalNetwork(netId, interface, ACTION_ADD); 939} 940 941int RouteController::removeInterfaceFromLocalNetwork(unsigned netId, const char* interface) { 942 return modifyLocalNetwork(netId, interface, ACTION_DEL); 943} 944 945int RouteController::addInterfaceToPhysicalNetwork(unsigned netId, const char* interface, 946 Permission permission) { 947 if (int ret = modifyPhysicalNetwork(netId, interface, permission, ACTION_ADD)) { 948 return ret; 949 } 950 updateTableNamesFile(); 951 return 0; 952} 953 954int RouteController::removeInterfaceFromPhysicalNetwork(unsigned netId, const char* interface, 955 Permission permission) { 956 if (int ret = modifyPhysicalNetwork(netId, interface, permission, ACTION_DEL)) { 957 return ret; 958 } 959 if (int ret = flushRoutes(interface)) { 960 return ret; 961 } 962 updateTableNamesFile(); 963 return 0; 964} 965 966int RouteController::addInterfaceToVirtualNetwork(unsigned netId, const char* interface, 967 bool secure, const UidRanges& uidRanges) { 968 if (int ret = modifyVirtualNetwork(netId, interface, uidRanges, secure, ACTION_ADD, 969 MODIFY_NON_UID_BASED_RULES)) { 970 return ret; 971 } 972 updateTableNamesFile(); 973 return 0; 974} 975 976int RouteController::removeInterfaceFromVirtualNetwork(unsigned netId, const char* interface, 977 bool secure, const UidRanges& uidRanges) { 978 if (int ret = modifyVirtualNetwork(netId, interface, uidRanges, secure, ACTION_DEL, 979 MODIFY_NON_UID_BASED_RULES)) { 980 return ret; 981 } 982 if (int ret = flushRoutes(interface)) { 983 return ret; 984 } 985 updateTableNamesFile(); 986 return 0; 987} 988 989int RouteController::modifyPhysicalNetworkPermission(unsigned netId, const char* interface, 990 Permission oldPermission, 991 Permission newPermission) { 992 // Add the new rules before deleting the old ones, to avoid race conditions. 993 if (int ret = modifyPhysicalNetwork(netId, interface, newPermission, ACTION_ADD)) { 994 return ret; 995 } 996 return modifyPhysicalNetwork(netId, interface, oldPermission, ACTION_DEL); 997} 998 999int RouteController::addUsersToVirtualNetwork(unsigned netId, const char* interface, bool secure, 1000 const UidRanges& uidRanges) { 1001 return modifyVirtualNetwork(netId, interface, uidRanges, secure, ACTION_ADD, 1002 !MODIFY_NON_UID_BASED_RULES); 1003} 1004 1005int RouteController::removeUsersFromVirtualNetwork(unsigned netId, const char* interface, 1006 bool secure, const UidRanges& uidRanges) { 1007 return modifyVirtualNetwork(netId, interface, uidRanges, secure, ACTION_DEL, 1008 !MODIFY_NON_UID_BASED_RULES); 1009} 1010 1011int RouteController::addInterfaceToDefaultNetwork(const char* interface, Permission permission) { 1012 return modifyDefaultNetwork(RTM_NEWRULE, interface, permission); 1013} 1014 1015int RouteController::removeInterfaceFromDefaultNetwork(const char* interface, 1016 Permission permission) { 1017 return modifyDefaultNetwork(RTM_DELRULE, interface, permission); 1018} 1019 1020int RouteController::addRoute(const char* interface, const char* destination, const char* nexthop, 1021 TableType tableType) { 1022 return modifyRoute(RTM_NEWROUTE, interface, destination, nexthop, tableType); 1023} 1024 1025int RouteController::removeRoute(const char* interface, const char* destination, 1026 const char* nexthop, TableType tableType) { 1027 return modifyRoute(RTM_DELROUTE, interface, destination, nexthop, tableType); 1028} 1029 1030int RouteController::enableTethering(const char* inputInterface, const char* outputInterface) { 1031 return modifyTetheredNetwork(RTM_NEWRULE, inputInterface, outputInterface); 1032} 1033 1034int RouteController::disableTethering(const char* inputInterface, const char* outputInterface) { 1035 return modifyTetheredNetwork(RTM_DELRULE, inputInterface, outputInterface); 1036} 1037 1038int RouteController::addVirtualNetworkFallthrough(unsigned vpnNetId, const char* physicalInterface, 1039 Permission permission) { 1040 return modifyVpnFallthroughRule(RTM_NEWRULE, vpnNetId, physicalInterface, permission); 1041} 1042 1043int RouteController::removeVirtualNetworkFallthrough(unsigned vpnNetId, 1044 const char* physicalInterface, 1045 Permission permission) { 1046 return modifyVpnFallthroughRule(RTM_DELRULE, vpnNetId, physicalInterface, permission); 1047} 1048