/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "RouteController.h"
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/fib_rules.h>
#include <net/if.h>
#include <sys/stat.h>
#include <private/android_filesystem_config.h>
#include <map>
#include "Fwmark.h"
#include "UidRanges.h"
#include "DummyNetwork.h"
#include "base/file.h"
#define LOG_TAG "Netd"
#include "log/log.h"
#include "logwrap/logwrap.h"
#include "netutils/ifc.h"
#include "resolv_netid.h"
using android::base::WriteStringToFile;
namespace {
// BEGIN CONSTANTS --------------------------------------------------------------------------------
const uint32_t RULE_PRIORITY_VPN_OVERRIDE_SYSTEM = 10000;
const uint32_t RULE_PRIORITY_VPN_OVERRIDE_OIF = 10500;
const uint32_t RULE_PRIORITY_VPN_OUTPUT_TO_LOCAL = 11000;
const uint32_t RULE_PRIORITY_SECURE_VPN = 12000;
const uint32_t RULE_PRIORITY_EXPLICIT_NETWORK = 13000;
const uint32_t RULE_PRIORITY_OUTPUT_INTERFACE = 14000;
const uint32_t RULE_PRIORITY_LEGACY_SYSTEM = 15000;
const uint32_t RULE_PRIORITY_LEGACY_NETWORK = 16000;
const uint32_t RULE_PRIORITY_LOCAL_NETWORK = 17000;
const uint32_t RULE_PRIORITY_TETHERING = 18000;
const uint32_t RULE_PRIORITY_IMPLICIT_NETWORK = 19000;
const uint32_t RULE_PRIORITY_BYPASSABLE_VPN = 20000;
const uint32_t RULE_PRIORITY_VPN_FALLTHROUGH = 21000;
const uint32_t RULE_PRIORITY_DEFAULT_NETWORK = 22000;
const uint32_t RULE_PRIORITY_DIRECTLY_CONNECTED = 23000;
const uint32_t RULE_PRIORITY_UNREACHABLE = 32000;
const uint32_t ROUTE_TABLE_LOCAL_NETWORK = 97;
const uint32_t ROUTE_TABLE_LEGACY_NETWORK = 98;
const uint32_t ROUTE_TABLE_LEGACY_SYSTEM = 99;
const char* const ROUTE_TABLE_NAME_LOCAL_NETWORK = "local_network";
const char* const ROUTE_TABLE_NAME_LEGACY_NETWORK = "legacy_network";
const char* const ROUTE_TABLE_NAME_LEGACY_SYSTEM = "legacy_system";
const char* const ROUTE_TABLE_NAME_LOCAL = "local";
const char* const ROUTE_TABLE_NAME_MAIN = "main";
// TODO: These values aren't defined by the Linux kernel, because our UID routing changes are not
// upstream (yet?), so we can't just pick them up from kernel headers. When (if?) the changes make
// it upstream, we'll remove this and rely on the kernel header values. For now, add a static assert
// that will warn us if upstream has given these values some other meaning.
const uint16_t FRA_UID_START = 18;
const uint16_t FRA_UID_END = 19;
static_assert(FRA_UID_START > FRA_MAX,
"Android-specific FRA_UID_{START,END} values also assigned in Linux uapi. "
"Check that these values match what the kernel does and then update this assertion.");
const uint16_t NETLINK_REQUEST_FLAGS = NLM_F_REQUEST | NLM_F_ACK;
const uint16_t NETLINK_CREATE_REQUEST_FLAGS = NETLINK_REQUEST_FLAGS | NLM_F_CREATE | NLM_F_EXCL;
const sockaddr_nl NETLINK_ADDRESS = {AF_NETLINK, 0, 0, 0};
const uint8_t AF_FAMILIES[] = {AF_INET, AF_INET6};
const char* const IP_VERSIONS[] = {"-4", "-6"};
const uid_t UID_ROOT = 0;
const char* const IIF_LOOPBACK = "lo";
const char* const IIF_NONE = NULL;
const char* const OIF_NONE = NULL;
const bool ACTION_ADD = true;
const bool ACTION_DEL = false;
const bool MODIFY_NON_UID_BASED_RULES = true;
const char* const RT_TABLES_PATH = "/data/misc/net/rt_tables";
const mode_t RT_TABLES_MODE = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH; // mode 0644, rw-r--r--
const unsigned ROUTE_FLUSH_ATTEMPTS = 2;
// Avoids "non-constant-expression cannot be narrowed from type 'unsigned int' to 'unsigned short'"
// warnings when using RTA_LENGTH(x) inside static initializers (even when x is already uint16_t).
constexpr uint16_t U16_RTA_LENGTH(uint16_t x) {
return RTA_LENGTH(x);
}
// These are practically const, but can't be declared so, because they are used to initialize
// non-const pointers ("void* iov_base") in iovec arrays.
rtattr FRATTR_PRIORITY = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_PRIORITY };
rtattr FRATTR_TABLE = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_TABLE };
rtattr FRATTR_FWMARK = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_FWMARK };
rtattr FRATTR_FWMASK = { U16_RTA_LENGTH(sizeof(uint32_t)), FRA_FWMASK };
rtattr FRATTR_UID_START = { U16_RTA_LENGTH(sizeof(uid_t)), FRA_UID_START };
rtattr FRATTR_UID_END = { U16_RTA_LENGTH(sizeof(uid_t)), FRA_UID_END };
rtattr RTATTR_TABLE = { U16_RTA_LENGTH(sizeof(uint32_t)), RTA_TABLE };
rtattr RTATTR_OIF = { U16_RTA_LENGTH(sizeof(uint32_t)), RTA_OIF };
uint8_t PADDING_BUFFER[RTA_ALIGNTO] = {0, 0, 0, 0};
// END CONSTANTS ----------------------------------------------------------------------------------
// No locks needed because RouteController is accessed only from one thread (in CommandListener).
std::map<std::string, uint32_t> interfaceToTable;
uint32_t getRouteTableForInterface(const char* interface) {
uint32_t index = if_nametoindex(interface);
if (index) {
index += RouteController::ROUTE_TABLE_OFFSET_FROM_INDEX;
interfaceToTable[interface] = index;
return index;
}
// If the interface goes away if_nametoindex() will return 0 but we still need to know
// the index so we can remove the rules and routes.
auto iter = interfaceToTable.find(interface);
if (iter == interfaceToTable.end()) {
ALOGE("cannot find interface %s", interface);
return RT_TABLE_UNSPEC;
}
return iter->second;
}
void addTableName(uint32_t table, const std::string& name, std::string* contents) {
char tableString[UINT32_STRLEN];
snprintf(tableString, sizeof(tableString), "%u", table);
*contents += tableString;
*contents += " ";
*contents += name;
*contents += "\n";
}
// Doesn't return success/failure as the file is optional; it's okay if we fail to update it.
void updateTableNamesFile() {
std::string contents;
addTableName(RT_TABLE_LOCAL, ROUTE_TABLE_NAME_LOCAL, &contents);
addTableName(RT_TABLE_MAIN, ROUTE_TABLE_NAME_MAIN, &contents);
addTableName(ROUTE_TABLE_LOCAL_NETWORK, ROUTE_TABLE_NAME_LOCAL_NETWORK, &contents);
addTableName(ROUTE_TABLE_LEGACY_NETWORK, ROUTE_TABLE_NAME_LEGACY_NETWORK, &contents);
addTableName(ROUTE_TABLE_LEGACY_SYSTEM, ROUTE_TABLE_NAME_LEGACY_SYSTEM, &contents);
for (const auto& entry : interfaceToTable) {
addTableName(entry.second, entry.first, &contents);
}
if (!WriteStringToFile(contents, RT_TABLES_PATH, RT_TABLES_MODE, AID_SYSTEM, AID_WIFI)) {
ALOGE("failed to write to %s (%s)", RT_TABLES_PATH, strerror(errno));
return;
}
}
// Sends a netlink request and expects an ack.
// |iov| is an array of struct iovec that contains the netlink message payload.
// The netlink header is generated by this function based on |action| and |flags|.
// Returns -errno if there was an error or if the kernel reported an error.
WARN_UNUSED_RESULT int sendNetlinkRequest(uint16_t action, uint16_t flags, iovec* iov, int iovlen) {
nlmsghdr nlmsg = {
.nlmsg_type = action,
.nlmsg_flags = flags,
};
iov[0].iov_base = &nlmsg;
iov[0].iov_len = sizeof(nlmsg);
for (int i = 0; i < iovlen; ++i) {
nlmsg.nlmsg_len += iov[i].iov_len;
}
int ret;
struct {
nlmsghdr msg;
nlmsgerr err;
} response;
int sock = socket(AF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, NETLINK_ROUTE);
if (sock != -1 &&
connect(sock, reinterpret_cast<const sockaddr*>(&NETLINK_ADDRESS),
sizeof(NETLINK_ADDRESS)) != -1 &&
writev(sock, iov, iovlen) != -1 &&
(ret = recv(sock, &response, sizeof(response), 0)) != -1) {
if (ret == sizeof(response)) {
ret = response.err.error; // Netlink errors are negative errno.
if (ret) {
ALOGE("netlink response contains error (%s)", strerror(-ret));
}
} else {
ALOGE("bad netlink response message size (%d != %zu)", ret, sizeof(response));
ret = -EBADMSG;
}
} else {
ALOGE("netlink socket/connect/writev/recv failed (%s)", strerror(errno));
ret = -errno;
}
if (sock != -1) {
close(sock);
}
return ret;
}
// Returns 0 on success or negative errno on failure.
int padInterfaceName(const char* input, char* name, size_t* length, uint16_t* padding) {
if (!input) {
*length = 0;
*padding = 0;
return 0;
}
*length = strlcpy(name, input, IFNAMSIZ) + 1;
if (*length > IFNAMSIZ) {
ALOGE("interface name too long (%zu > %u)", *length, IFNAMSIZ);
return -ENAMETOOLONG;
}
*padding = RTA_SPACE(*length) - RTA_LENGTH(*length);
return 0;
}
// Adds or removes a routing rule for IPv4 and IPv6.
//
// + If |priority| is RULE_PRIORITY_UNREACHABLE, the rule returns ENETUNREACH (i.e., specifies an
// action of FR_ACT_UNREACHABLE). Otherwise, the rule specifies an action of FR_ACT_TO_TBL.
// + If |table| is non-zero, the rule points at the specified routing table. Otherwise, the table is
// unspecified. An unspecified table is only allowed when deleting a rule.
// + If |mask| is non-zero, the rule matches the specified fwmark and mask. Otherwise, |fwmark| is
// ignored.
// + If |iif| is non-NULL, the rule matches the specified incoming interface.
// + If |oif| is non-NULL, the rule matches the specified outgoing interface.
// + If |uidStart| and |uidEnd| are not INVALID_UID, the rule matches packets from UIDs in that
// range (inclusive). Otherwise, the rule matches packets from all UIDs.
//
// Returns 0 on success or negative errno on failure.
WARN_UNUSED_RESULT int modifyIpRule(uint16_t action, uint32_t priority, uint32_t table,
uint32_t fwmark, uint32_t mask, const char* iif,
const char* oif, uid_t uidStart, uid_t uidEnd) {
// Ensure that if you set a bit in the fwmark, it's not being ignored by the mask.
if (fwmark & ~mask) {
ALOGE("mask 0x%x does not select all the bits set in fwmark 0x%x", mask, fwmark);
return -ERANGE;
}
// Interface names must include exactly one terminating NULL and be properly padded, or older
// kernels will refuse to delete rules.
char iifName[IFNAMSIZ], oifName[IFNAMSIZ];
size_t iifLength, oifLength;
uint16_t iifPadding, oifPadding;
if (int ret = padInterfaceName(iif, iifName, &iifLength, &iifPadding)) {
return ret;
}
if (int ret = padInterfaceName(oif, oifName, &oifLength, &oifPadding)) {
return ret;
}
// Either both start and end UID must be specified, or neither.
if ((uidStart == INVALID_UID) != (uidEnd == INVALID_UID)) {
ALOGE("incompatible start and end UIDs (%u vs %u)", uidStart, uidEnd);
return -EUSERS;
}
bool isUidRule = (uidStart != INVALID_UID);
// Assemble a rule request and put it in an array of iovec structures.
fib_rule_hdr rule = {
.action = static_cast<uint8_t>(priority != RULE_PRIORITY_UNREACHABLE ? FR_ACT_TO_TBL :
FR_ACT_UNREACHABLE),
// Note that here we're implicitly setting rule.table to 0. When we want to specify a
// non-zero table, we do this via the FRATTR_TABLE attribute.
};
// Don't ever create a rule that looks up table 0, because table 0 is the local table.
// It's OK to specify a table ID of 0 when deleting a rule, because that doesn't actually select
// table 0, it's a wildcard that matches anything.
if (table == RT_TABLE_UNSPEC && rule.action == FR_ACT_TO_TBL && action != RTM_DELRULE) {
ALOGE("RT_TABLE_UNSPEC only allowed when deleting rules");
return -ENOTUNIQ;
}
rtattr fraIifName = { U16_RTA_LENGTH(iifLength), FRA_IIFNAME };
rtattr fraOifName = { U16_RTA_LENGTH(oifLength), FRA_OIFNAME };
iovec iov[] = {
{ NULL, 0 },
{ &rule, sizeof(rule) },
{ &FRATTR_PRIORITY, sizeof(FRATTR_PRIORITY) },
{ &priority, sizeof(priority) },
{ &FRATTR_TABLE, table != RT_TABLE_UNSPEC ? sizeof(FRATTR_TABLE) : 0 },
{ &table, table != RT_TABLE_UNSPEC ? sizeof(table) : 0 },
{ &FRATTR_FWMARK, mask ? sizeof(FRATTR_FWMARK) : 0 },
{ &fwmark, mask ? sizeof(fwmark) : 0 },
{ &FRATTR_FWMASK, mask ? sizeof(FRATTR_FWMASK) : 0 },
{ &mask, mask ? sizeof(mask) : 0 },
{ &FRATTR_UID_START, isUidRule ? sizeof(FRATTR_UID_START) : 0 },
{ &uidStart, isUidRule ? sizeof(uidStart) : 0 },
{ &FRATTR_UID_END, isUidRule ? sizeof(FRATTR_UID_END) : 0 },
{ &uidEnd, isUidRule ? sizeof(uidEnd) : 0 },
{ &fraIifName, iif != IIF_NONE ? sizeof(fraIifName) : 0 },
{ iifName, iifLength },
{ PADDING_BUFFER, iifPadding },
{ &fraOifName, oif != OIF_NONE ? sizeof(fraOifName) : 0 },
{ oifName, oifLength },
{ PADDING_BUFFER, oifPadding },
};
uint16_t flags = (action == RTM_NEWRULE) ? NETLINK_CREATE_REQUEST_FLAGS : NETLINK_REQUEST_FLAGS;
for (size_t i = 0; i < ARRAY_SIZE(AF_FAMILIES); ++i) {
rule.family = AF_FAMILIES[i];
if (int ret = sendNetlinkRequest(action, flags, iov, ARRAY_SIZE(iov))) {
return ret;
}
}
return 0;
}
WARN_UNUSED_RESULT int modifyIpRule(uint16_t action, uint32_t priority, uint32_t table,
uint32_t fwmark, uint32_t mask) {
return modifyIpRule(action, priority, table, fwmark, mask, IIF_NONE, OIF_NONE, INVALID_UID,
INVALID_UID);
}
// Adds or deletes an IPv4 or IPv6 route.
// Returns 0 on success or negative errno on failure.
WARN_UNUSED_RESULT int modifyIpRoute(uint16_t action, uint32_t table, const char* interface,
const char* destination, const char* nexthop) {
// At least the destination must be non-null.
if (!destination) {
ALOGE("null destination");
return -EFAULT;
}
// Parse the prefix.
uint8_t rawAddress[sizeof(in6_addr)];
uint8_t family;
uint8_t prefixLength;
int rawLength = parsePrefix(destination, &family, rawAddress, sizeof(rawAddress),
&prefixLength);
if (rawLength < 0) {
ALOGE("parsePrefix failed for destination %s (%s)", destination, strerror(-rawLength));
return rawLength;
}
if (static_cast<size_t>(rawLength) > sizeof(rawAddress)) {
ALOGE("impossible! address too long (%d vs %zu)", rawLength, sizeof(rawAddress));
return -ENOBUFS; // Cannot happen; parsePrefix only supports IPv4 and IPv6.
}
uint8_t type = RTN_UNICAST;
uint32_t ifindex;
uint8_t rawNexthop[sizeof(in6_addr)];
if (nexthop && !strcmp(nexthop, "unreachable")) {
type = RTN_UNREACHABLE;
// 'interface' is likely non-NULL, as the caller (modifyRoute()) likely used it to lookup
// the table number. But it's an error to specify an interface ("dev ...") or a nexthop for
// unreachable routes, so nuke them. (IPv6 allows them to be specified; IPv4 doesn't.)
interface = OIF_NONE;
nexthop = NULL;
} else if (nexthop && !strcmp(nexthop, "throw")) {
type = RTN_THROW;
interface = OIF_NONE;
nexthop = NULL;
} else {
// If an interface was specified, find the ifindex.
if (interface != OIF_NONE) {
ifindex = if_nametoindex(interface);
if (!ifindex) {
ALOGE("cannot find interface %s", interface);
return -ENODEV;
}
}
// If a nexthop was specified, parse it as the same family as the prefix.
if (nexthop && inet_pton(family, nexthop, rawNexthop) <= 0) {
ALOGE("inet_pton failed for nexthop %s", nexthop);
return -EINVAL;
}
}
// Assemble a rtmsg and put it in an array of iovec structures.
rtmsg route = {
.rtm_protocol = RTPROT_STATIC,
.rtm_type = type,
.rtm_family = family,
.rtm_dst_len = prefixLength,
.rtm_scope = static_cast<uint8_t>(nexthop ? RT_SCOPE_UNIVERSE : RT_SCOPE_LINK),
};
rtattr rtaDst = { U16_RTA_LENGTH(rawLength), RTA_DST };
rtattr rtaGateway = { U16_RTA_LENGTH(rawLength), RTA_GATEWAY };
iovec iov[] = {
{ NULL, 0 },
{ &route, sizeof(route) },
{ &RTATTR_TABLE, sizeof(RTATTR_TABLE) },
{ &table, sizeof(table) },
{ &rtaDst, sizeof(rtaDst) },
{ rawAddress, static_cast<size_t>(rawLength) },
{ &RTATTR_OIF, interface != OIF_NONE ? sizeof(RTATTR_OIF) : 0 },
{ &ifindex, interface != OIF_NONE ? sizeof(ifindex) : 0 },
{ &rtaGateway, nexthop ? sizeof(rtaGateway) : 0 },
{ rawNexthop, nexthop ? static_cast<size_t>(rawLength) : 0 },
};
uint16_t flags = (action == RTM_NEWROUTE) ? NETLINK_CREATE_REQUEST_FLAGS :
NETLINK_REQUEST_FLAGS;
return sendNetlinkRequest(action, flags, iov, ARRAY_SIZE(iov));
}
// An iptables rule to mark incoming packets on a network with the netId of the network.
//
// This is so that the kernel can:
// + Use the right fwmark for (and thus correctly route) replies (e.g.: TCP RST, ICMP errors, ping
// replies, SYN-ACKs, etc).
// + Mark sockets that accept connections from this interface so that the connection stays on the
// same interface.
WARN_UNUSED_RESULT int modifyIncomingPacketMark(unsigned netId, const char* interface,
Permission permission, bool add) {
Fwmark fwmark;
fwmark.netId = netId;
fwmark.explicitlySelected = true;
fwmark.protectedFromVpn = true;
fwmark.permission = permission;
char markString[UINT32_HEX_STRLEN];
snprintf(markString, sizeof(markString), "0x%x", fwmark.intValue);
if (execIptables(V4V6, "-t", "mangle", add ? "-A" : "-D", "INPUT", "-i", interface, "-j",
"MARK", "--set-mark", markString, NULL)) {
ALOGE("failed to change iptables rule that sets incoming packet mark");
return -EREMOTEIO;
}
return 0;
}
// A rule to route responses to the local network forwarded via the VPN.
//
// When a VPN is in effect, packets from the local network to upstream networks are forwarded into
// the VPN's tunnel interface. When the VPN forwards the responses, they emerge out of the tunnel.
WARN_UNUSED_RESULT int modifyVpnOutputToLocalRule(const char* vpnInterface, bool add) {
return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_VPN_OUTPUT_TO_LOCAL,
ROUTE_TABLE_LOCAL_NETWORK, MARK_UNSET, MARK_UNSET, vpnInterface, OIF_NONE,
INVALID_UID, INVALID_UID);
}
// A rule to route all traffic from a given set of UIDs to go over the VPN.
//
// Notice that this rule doesn't use the netId. I.e., no matter what netId the user's socket may
// have, if they are subject to this VPN, their traffic has to go through it. Allows the traffic to
// bypass the VPN if the protectedFromVpn bit is set.
WARN_UNUSED_RESULT int modifyVpnUidRangeRule(uint32_t table, uid_t uidStart, uid_t uidEnd,
bool secure, bool add) {
Fwmark fwmark;
Fwmark mask;
fwmark.protectedFromVpn = false;
mask.protectedFromVpn = true;
uint32_t priority;
if (secure) {
priority = RULE_PRIORITY_SECURE_VPN;
} else {
priority = RULE_PRIORITY_BYPASSABLE_VPN;
fwmark.explicitlySelected = false;
mask.explicitlySelected = true;
}
return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, priority, table, fwmark.intValue,
mask.intValue, IIF_LOOPBACK, OIF_NONE, uidStart, uidEnd);
}
// A rule to allow system apps to send traffic over this VPN even if they are not part of the target
// set of UIDs.
//
// This is needed for DnsProxyListener to correctly resolve a request for a user who is in the
// target set, but where the DnsProxyListener itself is not.
WARN_UNUSED_RESULT int modifyVpnSystemPermissionRule(unsigned netId, uint32_t table, bool secure,
bool add) {
Fwmark fwmark;
Fwmark mask;
fwmark.netId = netId;
mask.netId = FWMARK_NET_ID_MASK;
fwmark.permission = PERMISSION_SYSTEM;
mask.permission = PERMISSION_SYSTEM;
uint32_t priority = secure ? RULE_PRIORITY_SECURE_VPN : RULE_PRIORITY_BYPASSABLE_VPN;
return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, priority, table, fwmark.intValue,
mask.intValue);
}
// A rule to route traffic based on an explicitly chosen network.
//
// Supports apps that use the multinetwork APIs to restrict their traffic to a network.
//
// Even though we check permissions at the time we set a netId into the fwmark of a socket, we need
// to check it again in the rules here, because a network's permissions may have been updated via
// modifyNetworkPermission().
WARN_UNUSED_RESULT int modifyExplicitNetworkRule(unsigned netId, uint32_t table,
Permission permission, uid_t uidStart,
uid_t uidEnd, bool add) {
Fwmark fwmark;
Fwmark mask;
fwmark.netId = netId;
mask.netId = FWMARK_NET_ID_MASK;
fwmark.explicitlySelected = true;
mask.explicitlySelected = true;
fwmark.permission = permission;
mask.permission = permission;
return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_EXPLICIT_NETWORK, table,
fwmark.intValue, mask.intValue, IIF_NONE, OIF_NONE, uidStart, uidEnd);
}
// A rule to route traffic based on a chosen outgoing interface.
//
// Supports apps that use SO_BINDTODEVICE or IP_PKTINFO options and the kernel that already knows
// the outgoing interface (typically for link-local communications).
WARN_UNUSED_RESULT int modifyOutputInterfaceRules(const char* interface, uint32_t table,
Permission permission, uid_t uidStart,
uid_t uidEnd, bool add) {
Fwmark fwmark;
Fwmark mask;
fwmark.permission = permission;
mask.permission = permission;
// If this rule does not specify a UID range, then also add a corresponding high-priority rule
// for UID. This covers forwarded packets and system daemons such as the tethering DHCP server.
if (uidStart == INVALID_UID && uidEnd == INVALID_UID) {
if (int ret = modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_VPN_OVERRIDE_OIF,
table, fwmark.intValue, mask.intValue, IIF_NONE, interface,
UID_ROOT, UID_ROOT)) {
return ret;
}
}
return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_OUTPUT_INTERFACE, table,
fwmark.intValue, mask.intValue, IIF_NONE, interface, uidStart, uidEnd);
}
// A rule to route traffic based on the chosen network.
//
// This is for sockets that have not explicitly requested a particular network, but have been
// bound to one when they called connect(). This ensures that sockets connected on a particular
// network stay on that network even if the default network changes.
WARN_UNUSED_RESULT int modifyImplicitNetworkRule(unsigned netId, uint32_t table,
Permission permission, bool add) {
Fwmark fwmark;
Fwmark mask;
fwmark.netId = netId;
mask.netId = FWMARK_NET_ID_MASK;
fwmark.explicitlySelected = false;
mask.explicitlySelected = true;
fwmark.permission = permission;
mask.permission = permission;
return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_IMPLICIT_NETWORK, table,
fwmark.intValue, mask.intValue);
}
// A rule to enable split tunnel VPNs.
//
// If a packet with a VPN's netId doesn't find a route in the VPN's routing table, it's allowed to
// go over the default network, provided it wasn't explicitly restricted to the VPN and has the
// permissions required by the default network.
WARN_UNUSED_RESULT int modifyVpnFallthroughRule(uint16_t action, unsigned vpnNetId,
const char* physicalInterface,
Permission permission) {
uint32_t table = getRouteTableForInterface(physicalInterface);
if (table == RT_TABLE_UNSPEC) {
return -ESRCH;
}
Fwmark fwmark;
Fwmark mask;
fwmark.netId = vpnNetId;
mask.netId = FWMARK_NET_ID_MASK;
fwmark.explicitlySelected = false;
mask.explicitlySelected = true;
fwmark.permission = permission;
mask.permission = permission;
return modifyIpRule(action, RULE_PRIORITY_VPN_FALLTHROUGH, table, fwmark.intValue,
mask.intValue);
}
// Add rules to allow legacy routes added through the requestRouteToHost() API.
WARN_UNUSED_RESULT int addLegacyRouteRules() {
Fwmark fwmark;
Fwmark mask;
fwmark.explicitlySelected = false;
mask.explicitlySelected = true;
// Rules to allow legacy routes to override the default network.
if (int ret = modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_LEGACY_SYSTEM, ROUTE_TABLE_LEGACY_SYSTEM,
fwmark.intValue, mask.intValue)) {
return ret;
}
if (int ret = modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_LEGACY_NETWORK,
ROUTE_TABLE_LEGACY_NETWORK, fwmark.intValue, mask.intValue)) {
return ret;
}
fwmark.permission = PERMISSION_SYSTEM;
mask.permission = PERMISSION_SYSTEM;
// A rule to allow legacy routes from system apps to override VPNs.
return modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_VPN_OVERRIDE_SYSTEM, ROUTE_TABLE_LEGACY_SYSTEM,
fwmark.intValue, mask.intValue);
}
// Add rules to lookup the local network when specified explicitly or otherwise.
WARN_UNUSED_RESULT int addLocalNetworkRules(unsigned localNetId) {
if (int ret = modifyExplicitNetworkRule(localNetId, ROUTE_TABLE_LOCAL_NETWORK, PERMISSION_NONE,
INVALID_UID, INVALID_UID, ACTION_ADD)) {
return ret;
}
Fwmark fwmark;
Fwmark mask;
fwmark.explicitlySelected = false;
mask.explicitlySelected = true;
return modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_LOCAL_NETWORK, ROUTE_TABLE_LOCAL_NETWORK,
fwmark.intValue, mask.intValue);
}
int configureDummyNetwork() {
const char *interface = DummyNetwork::INTERFACE_NAME;
uint32_t table = getRouteTableForInterface(interface);
if (table == RT_TABLE_UNSPEC) {
// getRouteTableForInterface has already looged an error.
return -ESRCH;
}
ifc_init();
int ret = ifc_up(interface);
ifc_close();
if (ret) {
ALOGE("Can't bring up %s: %s", interface, strerror(errno));
return -errno;
}
if ((ret = modifyOutputInterfaceRules(interface, table, PERMISSION_NONE,
INVALID_UID, INVALID_UID, ACTION_ADD))) {
ALOGE("Can't create oif rules for %s: %s", interface, strerror(-ret));
return ret;
}
if ((ret = modifyIpRoute(RTM_NEWROUTE, table, interface, "0.0.0.0/0", NULL))) {
ALOGE("Can't add IPv4 default route to %s: %s", interface, strerror(-ret));
return ret;
}
if ((ret = modifyIpRoute(RTM_NEWROUTE, table, interface, "::/0", NULL))) {
ALOGE("Can't add IPv6 default route to %s: %s", interface, strerror(-ret));
return ret;
}
return 0;
}
// Add a new rule to look up the 'main' table, with the same selectors as the "default network"
// rule, but with a lower priority. We will never create routes in the main table; it should only be
// used for directly-connected routes implicitly created by the kernel when adding IP addresses.
// This is necessary, for example, when adding a route through a directly-connected gateway: in
// order to add the route, there must already be a directly-connected route that covers the gateway.
WARN_UNUSED_RESULT int addDirectlyConnectedRule() {
Fwmark fwmark;
Fwmark mask;
fwmark.netId = NETID_UNSET;
mask.netId = FWMARK_NET_ID_MASK;
return modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_DIRECTLY_CONNECTED, RT_TABLE_MAIN,
fwmark.intValue, mask.intValue, IIF_NONE, OIF_NONE, UID_ROOT, UID_ROOT);
}
// Add an explicit unreachable rule close to the end of the prioriy list to make it clear that
// relying on the kernel-default "from all lookup main" rule at priority 32766 is not intended
// behaviour. We do flush the kernel-default rules at startup, but having an explicit unreachable
// rule will hopefully make things even clearer.
WARN_UNUSED_RESULT int addUnreachableRule() {
return modifyIpRule(RTM_NEWRULE, RULE_PRIORITY_UNREACHABLE, RT_TABLE_UNSPEC, MARK_UNSET,
MARK_UNSET);
}
WARN_UNUSED_RESULT int modifyLocalNetwork(unsigned netId, const char* interface, bool add) {
if (int ret = modifyIncomingPacketMark(netId, interface, PERMISSION_NONE, add)) {
return ret;
}
return modifyOutputInterfaceRules(interface, ROUTE_TABLE_LOCAL_NETWORK, PERMISSION_NONE,
INVALID_UID, INVALID_UID, add);
}
WARN_UNUSED_RESULT int modifyPhysicalNetwork(unsigned netId, const char* interface,
Permission permission, bool add) {
uint32_t table = getRouteTableForInterface(interface);
if (table == RT_TABLE_UNSPEC) {
return -ESRCH;
}
if (int ret = modifyIncomingPacketMark(netId, interface, permission, add)) {
return ret;
}
if (int ret = modifyExplicitNetworkRule(netId, table, permission, INVALID_UID, INVALID_UID,
add)) {
return ret;
}
if (int ret = modifyOutputInterfaceRules(interface, table, permission, INVALID_UID, INVALID_UID,
add)) {
return ret;
}
return modifyImplicitNetworkRule(netId, table, permission, add);
}
WARN_UNUSED_RESULT int modifyVirtualNetwork(unsigned netId, const char* interface,
const UidRanges& uidRanges, bool secure, bool add,
bool modifyNonUidBasedRules) {
uint32_t table = getRouteTableForInterface(interface);
if (table == RT_TABLE_UNSPEC) {
return -ESRCH;
}
for (const UidRanges::Range& range : uidRanges.getRanges()) {
if (int ret = modifyVpnUidRangeRule(table, range.first, range.second, secure, add)) {
return ret;
}
if (int ret = modifyExplicitNetworkRule(netId, table, PERMISSION_NONE, range.first,
range.second, add)) {
return ret;
}
if (int ret = modifyOutputInterfaceRules(interface, table, PERMISSION_NONE, range.first,
range.second, add)) {
return ret;
}
}
if (modifyNonUidBasedRules) {
if (int ret = modifyIncomingPacketMark(netId, interface, PERMISSION_NONE, add)) {
return ret;
}
if (int ret = modifyVpnOutputToLocalRule(interface, add)) {
return ret;
}
if (int ret = modifyVpnSystemPermissionRule(netId, table, secure, add)) {
return ret;
}
return modifyExplicitNetworkRule(netId, table, PERMISSION_NONE, UID_ROOT, UID_ROOT, add);
}
return 0;
}
WARN_UNUSED_RESULT int modifyDefaultNetwork(uint16_t action, const char* interface,
Permission permission) {
uint32_t table = getRouteTableForInterface(interface);
if (table == RT_TABLE_UNSPEC) {
return -ESRCH;
}
Fwmark fwmark;
Fwmark mask;
fwmark.netId = NETID_UNSET;
mask.netId = FWMARK_NET_ID_MASK;
fwmark.permission = permission;
mask.permission = permission;
return modifyIpRule(action, RULE_PRIORITY_DEFAULT_NETWORK, table, fwmark.intValue,
mask.intValue);
}
WARN_UNUSED_RESULT int modifyTetheredNetwork(uint16_t action, const char* inputInterface,
const char* outputInterface) {
uint32_t table = getRouteTableForInterface(outputInterface);
if (table == RT_TABLE_UNSPEC) {
return -ESRCH;
}
return modifyIpRule(action, RULE_PRIORITY_TETHERING, table, MARK_UNSET, MARK_UNSET,
inputInterface, OIF_NONE, INVALID_UID, INVALID_UID);
}
// Returns 0 on success or negative errno on failure.
WARN_UNUSED_RESULT int flushRules() {
for (size_t i = 0; i < ARRAY_SIZE(IP_VERSIONS); ++i) {
const char* argv[] = {
IP_PATH,
IP_VERSIONS[i],
"rule",
"flush",
};
if (android_fork_execvp(ARRAY_SIZE(argv), const_cast<char**>(argv), NULL, false, false)) {
ALOGE("failed to flush rules");
return -EREMOTEIO;
}
}
return 0;
}
// Adds or removes an IPv4 or IPv6 route to the specified table and, if it's a directly-connected
// route, to the main table as well.
// Returns 0 on success or negative errno on failure.
WARN_UNUSED_RESULT int modifyRoute(uint16_t action, const char* interface, const char* destination,
const char* nexthop, RouteController::TableType tableType) {
uint32_t table;
switch (tableType) {
case RouteController::INTERFACE: {
table = getRouteTableForInterface(interface);
if (table == RT_TABLE_UNSPEC) {
return -ESRCH;
}
break;
}
case RouteController::LOCAL_NETWORK: {
table = ROUTE_TABLE_LOCAL_NETWORK;
break;
}
case RouteController::LEGACY_NETWORK: {
table = ROUTE_TABLE_LEGACY_NETWORK;
break;
}
case RouteController::LEGACY_SYSTEM: {
table = ROUTE_TABLE_LEGACY_SYSTEM;
break;
}
}
int ret = modifyIpRoute(action, table, interface, destination, nexthop);
// Trying to add a route that already exists shouldn't cause an error.
if (ret && !(action == RTM_NEWROUTE && ret == -EEXIST)) {
return ret;
}
return 0;
}
// Returns 0 on success or negative errno on failure.
WARN_UNUSED_RESULT int flushRoutes(const char* interface) {
uint32_t table = getRouteTableForInterface(interface);
if (table == RT_TABLE_UNSPEC) {
return -ESRCH;
}
char tableString[UINT32_STRLEN];
snprintf(tableString, sizeof(tableString), "%u", table);
int ret = 0;
for (size_t i = 0; i < ARRAY_SIZE(IP_VERSIONS); ++i) {
const char* argv[] = {
IP_PATH,
IP_VERSIONS[i],
"route",
"flush",
"table",
tableString,
};
// A flush works by dumping routes and deleting each route as it's returned, and it can
// fail if something else deletes the route between the dump and the delete. This can
// happen, for example, if an interface goes down while we're trying to flush its routes.
// So try multiple times and only return an error if the last attempt fails.
//
// TODO: replace this with our own netlink code.
unsigned attempts = 0;
int err;
do {
err = android_fork_execvp(ARRAY_SIZE(argv), const_cast<char**>(argv),
NULL, false, false);
++attempts;
} while (err != 0 && attempts < ROUTE_FLUSH_ATTEMPTS);
if (err) {
ALOGE("failed to flush %s routes in table %s after %d attempts",
IP_VERSIONS[i], tableString, attempts);
ret = -EREMOTEIO;
}
}
// If we failed to flush routes, the caller may elect to keep this interface around, so keep
// track of its name.
if (!ret) {
interfaceToTable.erase(interface);
}
return ret;
}
WARN_UNUSED_RESULT int clearTetheringRules(const char* inputInterface) {
int ret = 0;
while (ret == 0) {
ret = modifyIpRule(RTM_DELRULE, RULE_PRIORITY_TETHERING, 0, MARK_UNSET, MARK_UNSET,
inputInterface, OIF_NONE, INVALID_UID, INVALID_UID);
}
if (ret == -ENOENT) {
return 0;
} else {
return ret;
}
}
} // namespace
int RouteController::Init(unsigned localNetId) {
if (int ret = flushRules()) {
return ret;
}
if (int ret = addLegacyRouteRules()) {
return ret;
}
if (int ret = addLocalNetworkRules(localNetId)) {
return ret;
}
if (int ret = addDirectlyConnectedRule()) {
return ret;
}
if (int ret = addUnreachableRule()) {
return ret;
}
// Don't complain if we can't add the dummy network, since not all devices support it.
configureDummyNetwork();
updateTableNamesFile();
return 0;
}
int RouteController::addInterfaceToLocalNetwork(unsigned netId, const char* interface) {
return modifyLocalNetwork(netId, interface, ACTION_ADD);
}
int RouteController::removeInterfaceFromLocalNetwork(unsigned netId, const char* interface) {
return modifyLocalNetwork(netId, interface, ACTION_DEL);
}
int RouteController::addInterfaceToPhysicalNetwork(unsigned netId, const char* interface,
Permission permission) {
if (int ret = modifyPhysicalNetwork(netId, interface, permission, ACTION_ADD)) {
return ret;
}
updateTableNamesFile();
return 0;
}
int RouteController::removeInterfaceFromPhysicalNetwork(unsigned netId, const char* interface,
Permission permission) {
if (int ret = modifyPhysicalNetwork(netId, interface, permission, ACTION_DEL)) {
return ret;
}
if (int ret = flushRoutes(interface)) {
return ret;
}
if (int ret = clearTetheringRules(interface)) {
return ret;
}
updateTableNamesFile();
return 0;
}
int RouteController::addInterfaceToVirtualNetwork(unsigned netId, const char* interface,
bool secure, const UidRanges& uidRanges) {
if (int ret = modifyVirtualNetwork(netId, interface, uidRanges, secure, ACTION_ADD,
MODIFY_NON_UID_BASED_RULES)) {
return ret;
}
updateTableNamesFile();
return 0;
}
int RouteController::removeInterfaceFromVirtualNetwork(unsigned netId, const char* interface,
bool secure, const UidRanges& uidRanges) {
if (int ret = modifyVirtualNetwork(netId, interface, uidRanges, secure, ACTION_DEL,
MODIFY_NON_UID_BASED_RULES)) {
return ret;
}
if (int ret = flushRoutes(interface)) {
return ret;
}
updateTableNamesFile();
return 0;
}
int RouteController::modifyPhysicalNetworkPermission(unsigned netId, const char* interface,
Permission oldPermission,
Permission newPermission) {
// Add the new rules before deleting the old ones, to avoid race conditions.
if (int ret = modifyPhysicalNetwork(netId, interface, newPermission, ACTION_ADD)) {
return ret;
}
return modifyPhysicalNetwork(netId, interface, oldPermission, ACTION_DEL);
}
int RouteController::addUsersToVirtualNetwork(unsigned netId, const char* interface, bool secure,
const UidRanges& uidRanges) {
return modifyVirtualNetwork(netId, interface, uidRanges, secure, ACTION_ADD,
!MODIFY_NON_UID_BASED_RULES);
}
int RouteController::removeUsersFromVirtualNetwork(unsigned netId, const char* interface,
bool secure, const UidRanges& uidRanges) {
return modifyVirtualNetwork(netId, interface, uidRanges, secure, ACTION_DEL,
!MODIFY_NON_UID_BASED_RULES);
}
int RouteController::addInterfaceToDefaultNetwork(const char* interface, Permission permission) {
return modifyDefaultNetwork(RTM_NEWRULE, interface, permission);
}
int RouteController::removeInterfaceFromDefaultNetwork(const char* interface,
Permission permission) {
return modifyDefaultNetwork(RTM_DELRULE, interface, permission);
}
int RouteController::addRoute(const char* interface, const char* destination, const char* nexthop,
TableType tableType) {
return modifyRoute(RTM_NEWROUTE, interface, destination, nexthop, tableType);
}
int RouteController::removeRoute(const char* interface, const char* destination,
const char* nexthop, TableType tableType) {
return modifyRoute(RTM_DELROUTE, interface, destination, nexthop, tableType);
}
int RouteController::enableTethering(const char* inputInterface, const char* outputInterface) {
return modifyTetheredNetwork(RTM_NEWRULE, inputInterface, outputInterface);
}
int RouteController::disableTethering(const char* inputInterface, const char* outputInterface) {
return modifyTetheredNetwork(RTM_DELRULE, inputInterface, outputInterface);
}
int RouteController::addVirtualNetworkFallthrough(unsigned vpnNetId, const char* physicalInterface,
Permission permission) {
return modifyVpnFallthroughRule(RTM_NEWRULE, vpnNetId, physicalInterface, permission);
}
int RouteController::removeVirtualNetworkFallthrough(unsigned vpnNetId,
const char* physicalInterface,
Permission permission) {
return modifyVpnFallthroughRule(RTM_DELRULE, vpnNetId, physicalInterface, permission);
}