diff options
| -rw-r--r-- | server/PhysicalNetwork.cpp | 13 | ||||
| -rw-r--r-- | server/PhysicalNetwork.h | 1 | ||||
| -rw-r--r-- | server/RouteController.cpp | 46 |
3 files changed, 55 insertions, 5 deletions
diff --git a/server/PhysicalNetwork.cpp b/server/PhysicalNetwork.cpp index ccac3233..579d0bdd 100644 --- a/server/PhysicalNetwork.cpp +++ b/server/PhysicalNetwork.cpp @@ -86,6 +86,18 @@ int PhysicalNetwork::destroySocketsLackingPermission(Permission permission) { return 0; } +void PhysicalNetwork::invalidateRouteCache(const std::string& interface) { + for (const auto& dst : { "0.0.0.0/0", "::/0" }) { + // If any of these operations fail, there's no point in logging because RouteController will + // have already logged a message. There's also no point returning an error since there's + // nothing we can do. + (void) RouteController::addRoute(interface.c_str(), dst, "throw", + RouteController::INTERFACE); + (void) RouteController::removeRoute(interface.c_str(), dst, "throw", + RouteController::INTERFACE); + } +} + int PhysicalNetwork::setPermission(Permission permission) { if (permission == mPermission) { return 0; @@ -103,6 +115,7 @@ int PhysicalNetwork::setPermission(Permission permission) { interface.c_str(), mNetId, mPermission, permission); return ret; } + invalidateRouteCache(interface); } if (mIsDefault) { for (const std::string& interface : mInterfaces) { diff --git a/server/PhysicalNetwork.h b/server/PhysicalNetwork.h index 9200955f..89c9443b 100644 --- a/server/PhysicalNetwork.h +++ b/server/PhysicalNetwork.h @@ -50,6 +50,7 @@ private: int addInterface(const std::string& interface) override WARN_UNUSED_RESULT; int removeInterface(const std::string& interface) override WARN_UNUSED_RESULT; int destroySocketsLackingPermission(Permission permission); + void invalidateRouteCache(const std::string& interface); Delegate* const mDelegate; Permission mPermission; diff --git a/server/RouteController.cpp b/server/RouteController.cpp index aeed3e9e..26e8407b 100644 --- a/server/RouteController.cpp +++ b/server/RouteController.cpp @@ -81,6 +81,14 @@ 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"; +// None of our routes specify priority, which causes them to have the default +// priority. For throw routes, we use a fixed priority of 100000. This is +// because we use throw routes either for maximum-length routes (/32 for IPv4, +// /128 for IPv6), which we never create with any other priority, or for +// purposely-low-priority default routes that should never match if there is +// any other route in the table. +uint32_t PRIO_THROW = 100000; + const char* const RouteController::LOCAL_MANGLE_INPUT = "routectrl_mangle_INPUT"; // These values are upstream, but not yet in our headers. @@ -120,6 +128,7 @@ rtattr FRATTR_UID_RANGE = { U16_RTA_LENGTH(sizeof(fib_rule_uid_range)), FRA_UID_ rtattr RTATTR_TABLE = { U16_RTA_LENGTH(sizeof(uint32_t)), RTA_TABLE }; rtattr RTATTR_OIF = { U16_RTA_LENGTH(sizeof(uint32_t)), RTA_OIF }; +rtattr RTATTR_PRIO = { U16_RTA_LENGTH(sizeof(uint32_t)), RTA_PRIORITY }; uint8_t PADDING_BUFFER[RTA_ALIGNTO] = {0, 0, 0, 0}; @@ -373,6 +382,8 @@ WARN_UNUSED_RESULT int modifyIpRoute(uint16_t action, uint32_t table, const char } } + bool isDefaultThrowRoute = (type == RTN_THROW && prefixLength == 0); + // Assemble a rtmsg and put it in an array of iovec structures. rtmsg route = { .rtm_protocol = RTPROT_STATIC, @@ -396,6 +407,8 @@ WARN_UNUSED_RESULT int modifyIpRoute(uint16_t action, uint32_t table, const char { &ifindex, interface != OIF_NONE ? sizeof(ifindex) : 0 }, { &rtaGateway, nexthop ? sizeof(rtaGateway) : 0 }, { rawNexthop, nexthop ? static_cast<size_t>(rawLength) : 0 }, + { &RTATTR_PRIO, isDefaultThrowRoute ? sizeof(RTATTR_PRIO) : 0 }, + { &PRIO_THROW, isDefaultThrowRoute ? sizeof(PRIO_THROW) : 0 }, }; uint16_t flags = (action == RTM_NEWROUTE) ? NETLINK_CREATE_REQUEST_FLAGS : @@ -553,8 +566,7 @@ WARN_UNUSED_RESULT int modifyOutputInterfaceRules(const char* interface, uint32_ // 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) { +WARN_UNUSED_RESULT int modifyImplicitNetworkRule(unsigned netId, uint32_t table, bool add) { Fwmark fwmark; Fwmark mask; @@ -564,8 +576,8 @@ WARN_UNUSED_RESULT int modifyImplicitNetworkRule(unsigned netId, uint32_t table, fwmark.explicitlySelected = false; mask.explicitlySelected = true; - fwmark.permission = permission; - mask.permission = permission; + fwmark.permission = PERMISSION_NONE; + mask.permission = PERMISSION_NONE; return modifyIpRule(add ? RTM_NEWRULE : RTM_DELRULE, RULE_PRIORITY_IMPLICIT_NETWORK, table, fwmark.intValue, mask.intValue); @@ -727,7 +739,31 @@ WARN_UNUSED_RESULT int modifyPhysicalNetwork(unsigned netId, const char* interfa add)) { return ret; } - return modifyImplicitNetworkRule(netId, table, permission, add); + + // Only set implicit rules for networks that don't require permissions. + // + // This is so that if the default network ceases to be the default network and then switches + // from requiring no permissions to requiring permissions, we ensure that apps only use the + // network if they explicitly select it. This is consistent with destroySocketsLackingPermission + // - it closes all sockets on the network except sockets that are explicitly selected. + // + // The lack of this rule only affects the special case above, because: + // - The only cases where we implicitly bind a socket to a network are the default network and + // the bypassable VPN that applies to the app, if any. + // - This rule doesn't affect VPNs because they don't support permissions at all. + // - The default network doesn't require permissions. While we support doing this, the framework + // never does it (partly because we'd end up in the situation where we tell apps that there is + // a default network, but they can't use it). + // - If the network is still the default network, the presence or absence of this rule does not + // matter. + // + // Therefore, for the lack of this rule to affect a socket, the socket has to have been + // implicitly bound to a network because at the time of connect() it was the default, and that + // network must no longer be the default, and must now require permissions. + if (permission == PERMISSION_NONE) { + return modifyImplicitNetworkRule(netId, table, add); + } + return 0; } WARN_UNUSED_RESULT int modifyRejectNonSecureNetworkRule(const UidRanges& uidRanges, bool add) { |