Skip to content

Fixes to route mirroring #40099

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
FetoiuCatalin merged 12 commits into from
Apr 13, 2026
Merged

Fixes to route mirroring #40099

Show file tree
Hide file tree
Changes from 6 commits
Commits
Show all changes
12 commits
Select commit Hold shift + click to select a range
9d6c794
route fixes from protonvpn testing
Mar 18, 2026
35dc5a2
add unit test, fix log
Mar 27, 2026
f5dab4d
ai code review
Apr 3, 2026
9c60a6d
format with vs 2022
Apr 6, 2026
832f9a4
review
Apr 7, 2026
f8b18f3
remove optional has_value checks
Apr 8, 2026
1cd758b
harden contracts for to, via having or not having values
Apr 9, 2026
6a5ac00
update IsOnlink check
Apr 9, 2026
4b8fa18
fix constructor parameters
Apr 9, 2026
ecfda02
Merge branch 'master' into user/cfetoiu/vpn_route_fixes
Apr 10, 2026
f91ae3d
fix merge conflicts
Apr 10, 2026
6414373
fix build
Apr 10, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
64 changes: 48 additions & 16 deletions src/linux/netlinkutil/RoutingTable.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -111,6 +111,10 @@ void RoutingTable::ModifyRouteImpl(const Route& route, Operation action)
{
ModifyLoopbackRouteImpl<TAddr>(route, operation, flags);
}
else if (route.defaultRoute && route.IsOnlink())
{
ModifyDefaultLinkLocalRouteImpl<TAddr>(route, operation, flags);
}
else if (route.defaultRoute)
{
ModifyDefaultRouteImpl<TAddr>(route, operation, flags);
Expand Down Expand Up @@ -193,8 +197,8 @@ void RoutingTable::ModifyLoopbackRouteImpl(const Route& route, int operation, in

GNS_LOG_INFO(
"SendMessage Route (to {}, via {}), operation ({}), netLinkflags ({})",
route.to.has_value() ? route.to.value().Addr().c_str() : "[empty]",
route.via.has_value() ? route.via.value().Addr().c_str() : "[empty]",
route.to.value().Addr().c_str(),
route.via.value().Addr().c_str(),
RouteOperationToString(operation),
NetLinkFormatFlagsToString(flags).c_str());

Expand Down Expand Up @@ -222,14 +226,33 @@ void RoutingTable::ModifyLoopbackRouteImpl(const Route& route, int operation, in

message.route.rtm_flags |= RTNH_F_ONLINK;
GNS_LOG_INFO(
"InitializeAddressAttribute RTA_DST ({}) RTA_GATEWAY ({}) RTA_PRIORITY ([not set])",
"Netlink message configuration: RTA_DST ({}) RTA_GATEWAY ({}) RTA_PRIORITY ([not set])",
route.to.value().Addr().c_str(),
route.via.value().Addr().c_str());
utils::InitializeAddressAttribute<TAddr>(message.to, route.to.value(), RTA_DST);
utils::InitializeAddressAttribute<TAddr>(message.via, route.via.value(), RTA_GATEWAY);
});
}

template <typename TAddr>
void RoutingTable::ModifyDefaultLinkLocalRouteImpl(const Route& route, int operation, int flags)
Comment thread
FetoiuCatalin marked this conversation as resolved.
{
struct Message : RouteMessage
{
utils::IntegerAttribute metric;
} __attribute__((packed));

GNS_LOG_INFO(
"SendMessage Route (default onlink), operation ({}), netLinkflags ({})",
RouteOperationToString(operation),
NetLinkFormatFlagsToString(flags).c_str());

SendMessage<Message>(route, operation, flags, [&](Message& message) {
GNS_LOG_INFO("Netlink message configuration: RTA_DST ([not set]) RTA_GATEWAY ([not set]), RTA_PRIORITY ({})", route.metric);
utils::InitializeIntegerAttribute(message.metric, route.metric, RTA_PRIORITY);
});
}

template <typename TAddr>
void RoutingTable::ModifyDefaultRouteImpl(const Route& route, int operation, int flags)
{
Expand All @@ -246,15 +269,15 @@ void RoutingTable::ModifyDefaultRouteImpl(const Route& route, int operation, int

GNS_LOG_INFO(
"SendMessage Route (to {}, via {}), operation ({}), netLinkflags ({})",
route.to.has_value() ? route.to.value().Addr().c_str() : "[empty]",
route.via.has_value() ? route.via.value().Addr().c_str() : "[empty]",
"[empty]",
Comment thread
keith-horton marked this conversation as resolved.
route.via.value().Addr().c_str(),
RouteOperationToString(operation),
NetLinkFormatFlagsToString(flags).c_str());

SendMessage<Message>(route, operation, flags, [&](Message& message) {
GNS_LOG_INFO(
"InitializeAddressAttribute RTA_DST ([not set]) RTA_GATEWAY ({}), RTA_PRIORITY ({})",
route.to.has_value() ? route.to.value().Addr().c_str() : "[empty]",
"Netlink message configuration: RTA_DST ([not set]) RTA_GATEWAY ({}), RTA_PRIORITY ({})",
route.via.value().Addr().c_str(),
route.metric);
utils::InitializeAddressAttribute<TAddr>(message.via, route.via.value(), RTA_GATEWAY);
Comment thread
keith-horton marked this conversation as resolved.
utils::InitializeIntegerAttribute(message.metric, route.metric, RTA_PRIORITY);
Expand All @@ -264,6 +287,11 @@ void RoutingTable::ModifyDefaultRouteImpl(const Route& route, int operation, int
template <typename TAddr>
void RoutingTable::ModifyLinkLocalRouteImpl(const Route& route, int operation, int flags)
{
if (!route.to.has_value())
{
throw RuntimeErrorWithSourceLocation("Link-local route is missing its destination address");
}

struct Message : RouteMessage
{
utils::AddressAttribute<TAddr> to;
Expand All @@ -272,15 +300,15 @@ void RoutingTable::ModifyLinkLocalRouteImpl(const Route& route, int operation, i

GNS_LOG_INFO(
"SendMessage Route (to {}, via {}), operation ({}), netLinkflags ({})",
route.to.has_value() ? route.to.value().Addr().c_str() : "[empty]",
route.via.has_value() ? route.via.value().Addr().c_str() : "[empty]",
route.to.value().Addr().c_str(),
"[empty]",
Comment thread
keith-horton marked this conversation as resolved.
RouteOperationToString(operation),
NetLinkFormatFlagsToString(flags).c_str());

SendMessage<Message>(route, operation, flags, [&](Message& message) {
GNS_LOG_INFO(
"InitializeAddressAttribute RTA_DST ({}) RTA_GATEWAY ([not set]), RTA_PRIORITY ({})",
route.to.has_value() ? route.to.value().Addr().c_str() : "[empty]",
"Netlink message configuration: RTA_DST ({}) RTA_GATEWAY ([not set]), RTA_PRIORITY ({})",
route.to.value().Addr().c_str(),
route.metric);
utils::InitializeAddressAttribute<TAddr>(message.to, route.to.value(), RTA_DST);
utils::InitializeIntegerAttribute(message.metric, route.metric, RTA_PRIORITY);
Expand All @@ -294,6 +322,10 @@ void RoutingTable::ModifyOfflinkRouteImpl(const Route& route, int operation, int
{
throw RuntimeErrorWithSourceLocation("Offlink route is missing its next hop");
}
if (!route.to.has_value())
Comment thread
FetoiuCatalin marked this conversation as resolved.
{
throw RuntimeErrorWithSourceLocation("Offlink route is missing its destination address");
}

struct Message : RouteMessage
{
Expand All @@ -304,16 +336,16 @@ void RoutingTable::ModifyOfflinkRouteImpl(const Route& route, int operation, int

GNS_LOG_INFO(
"SendMessage Route (to {}, via {}), operation ({}), netLinkflags ({})",
route.to.has_value() ? route.to.value().Addr().c_str() : "[empty]",
route.via.has_value() ? route.via.value().Addr().c_str() : "[empty]",
route.to.value().Addr().c_str(),
route.via.value().Addr().c_str(),
RouteOperationToString(operation),
NetLinkFormatFlagsToString(flags).c_str());

SendMessage<Message>(route, operation, flags, [&](Message& message) {
GNS_LOG_INFO(
"InitializeAddressAttribute RTA_DST ({}) RTA_GATEWAY ({}), RTA_PRIORITY ({})",
route.to.has_value() ? route.to.value().Addr().c_str() : "[empty]",
route.via.has_value() ? route.via.value().Addr().c_str() : "[empty]",
"Netlink message configuration: RTA_DST ({}) RTA_GATEWAY ({}), RTA_PRIORITY ({})",
route.to.value().Addr().c_str(),
route.via.value().Addr().c_str(),
route.metric);
utils::InitializeAddressAttribute<TAddr>(message.to, route.to.value(), RTA_DST);
utils::InitializeAddressAttribute<TAddr>(message.via, route.via.value(), RTA_GATEWAY);
Expand Down
3 changes: 3 additions & 0 deletions src/linux/netlinkutil/RoutingTable.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,9 @@ class RoutingTable
template <typename TAddr>
void ModifyDefaultRouteImpl(const Route& route, int operation, int flags);

template <typename TAddr>
void ModifyDefaultLinkLocalRouteImpl(const Route& route, int operation, int flags);

template <typename TAddr>
void ModifyLinkLocalRouteImpl(const Route& route, int operation, int flags);

Expand Down
9 changes: 9 additions & 0 deletions src/windows/service/exe/WslMirroredNetworking.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -347,6 +347,15 @@ void wsl::core::networking::WslMirroredNetworkManager::ProcessRouteChange()
{
endpointRoute.Metric = UINT16_MAX;
}

// Some Windows interfaces (like VPNs) can have metric 0 and routes over that interface with metric also 0, adding
// up to 0. Linux treats metric 0 as unspecified and will default to a 1024 metric. The highest priority metric in
// Linux is 1 instead so we need to switch the metric from 0 to 1.
if (endpointRoute.Metric == 0)
{
endpointRoute.Metric = 1;
}

endpoint.Network->Routes.insert(endpointRoute);
}
}
Expand Down
37 changes: 37 additions & 0 deletions test/windows/NetworkTests.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -352,6 +352,43 @@ class NetworkTests
VERIFY_ARE_EQUAL(v6State.DefaultRoute->Device, L"eth0");
}

TEST_METHOD(AddRemoveDefaultOnlinkRoutes)
{
WSL2_TEST_ONLY();

wsl::shared::hns::Route defaultRouteV4;
defaultRouteV4.NextHop = L"0.0.0.0";
defaultRouteV4.DestinationPrefix = LX_INIT_DEFAULT_ROUTE_PREFIX;
defaultRouteV4.Family = AF_INET;
defaultRouteV4.Metric = 1;
Comment thread
keith-horton marked this conversation as resolved.
SendDeviceSettingsRequest(L"eth0", defaultRouteV4, ModifyRequestType::Add, GuestEndpointResourceType::Route);

wsl::shared::hns::Route defaultRouteV6;
defaultRouteV6.NextHop = L"::";
defaultRouteV6.DestinationPrefix = LX_INIT_DEFAULT_ROUTE_V6_PREFIX;
defaultRouteV6.Family = AF_INET6;
defaultRouteV6.Metric = 1;
Comment thread
FetoiuCatalin marked this conversation as resolved.
SendDeviceSettingsRequest(L"eth0", defaultRouteV6, ModifyRequestType::Add, GuestEndpointResourceType::Route);
Comment thread
FetoiuCatalin marked this conversation as resolved.

const bool defaultV4RouteExists =
LxsstuLaunchWsl(L"ip -4 route show | grep \"default dev eth0\" | grep -w \"metric 1\"") == (DWORD)0;
const bool defaultV6RouteExists =
LxsstuLaunchWsl(L"ip -6 route show | grep \"default dev eth0\" | grep -w \"metric 1\"") == (DWORD)0;

SendDeviceSettingsRequest(L"eth0", defaultRouteV4, ModifyRequestType::Remove, GuestEndpointResourceType::Route);
SendDeviceSettingsRequest(L"eth0", defaultRouteV6, ModifyRequestType::Remove, GuestEndpointResourceType::Route);
Comment thread
FetoiuCatalin marked this conversation as resolved.

const bool defaultV4RouteRemoved =
LxsstuLaunchWsl(L"ip -4 route show | grep \"default dev eth0\" | grep -w \"metric 1\"") != (DWORD)0;
const bool defaultV6RouteRemoved =
LxsstuLaunchWsl(L"ip -6 route show | grep \"default dev eth0\" | grep -w \"metric 1\"") != (DWORD)0;

VERIFY_IS_TRUE(defaultV4RouteExists);
VERIFY_IS_TRUE(defaultV6RouteExists);
VERIFY_IS_TRUE(defaultV4RouteRemoved);
VERIFY_IS_TRUE(defaultV6RouteRemoved);
}

TEST_METHOD(SetInterfaceDownAndUp)
{
WSL2_TEST_ONLY();
Expand Down
Loading