Skip to content

fix(wgengine): Guard endpoint dispatcher via wrapper #7

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
merged 1 commit into from
Mar 7, 2023
Merged

fix(wgengine): Guard endpoint dispatcher via wrapper #7

Changes from all commits
Commits
Show all changes
1 commit
Select commit
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
51 changes: 40 additions & 11 deletions wgengine/netstack/netstack.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -97,7 +97,7 @@ type Impl struct {

ipstack *stack.Stack
epMu sync.RWMutex
linkEP *channel.Endpoint
linkEP *protectedLinkEndpoint
tundev *tstun.Wrapper
e wgengine.Engine
mc *magicsock.Conn
Expand Down Expand Up @@ -159,7 +159,7 @@ func Create(logf logger.Logf, tundev *tstun.Wrapper, e wgengine.Engine, mc *magi
if tcpipErr != nil {
return nil, fmt.Errorf("could not enable TCP SACK: %v", tcpipErr)
}
linkEP := channel.New(512, mtu, "")
linkEP := &protectedLinkEndpoint{Endpoint: channel.New(512, mtu, "")}
if tcpipProblem := ipstack.CreateNIC(nicID, linkEP); tcpipProblem != nil {
return nil, fmt.Errorf("could not create netstack NIC: %v", tcpipProblem)
}
Expand Down Expand Up @@ -202,9 +202,7 @@ func Create(logf logger.Logf, tundev *tstun.Wrapper, e wgengine.Engine, mc *magi
func (ns *Impl) Close() error {
ns.ctxCancel()
ns.ipstack.Close()
ns.epMu.Lock()
ns.ipstack.Wait()
ns.epMu.Unlock()
return nil
}

Expand Down Expand Up @@ -689,13 +687,7 @@ func (ns *Impl) injectInbound(p *packet.Parsed, t *tstun.Wrapper) filter.Respons
packetBuf := stack.NewPacketBuffer(stack.PacketBufferOptions{
Payload: bufferv2.MakeWithData(bytes.Clone(p.Buffer())),
})

if ns.epMu.TryRLock() {
if ns.linkEP.IsAttached() {
ns.linkEP.InjectInbound(pn, packetBuf)
}
ns.epMu.RUnlock()
}
ns.linkEP.InjectInbound(pn, packetBuf)
packetBuf.DecRef()

// We've now delivered this to netstack, so we're done.
Expand Down Expand Up @@ -1216,3 +1208,40 @@ func ipPortOfNetstackAddr(a tcpip.Address, port uint16) (ipp netip.AddrPort, ok
return ipp, false
}
}

// protectedLinkEndpoint guards use of the dispatcher via mutex and forwards
// everything except Attach/InjectInbound to the underlying *channel.Endpoint.
type protectedLinkEndpoint struct {
mu sync.RWMutex
dispatcher stack.NetworkDispatcher
*channel.Endpoint
}

// InjectInbound injects an inbound packet.
func (e *protectedLinkEndpoint) InjectInbound(protocol tcpip.NetworkProtocolNumber, pkt stack.PacketBufferPtr) {
e.mu.RLock()
dispatcher := e.dispatcher
e.mu.RUnlock()
if dispatcher != nil {
dispatcher.DeliverNetworkPacket(protocol, pkt)
}
}

// Attach saves the stack network-layer dispatcher for use later when packets
// are injected.
func (e *protectedLinkEndpoint) Attach(dispatcher stack.NetworkDispatcher) {
e.mu.Lock()
defer e.mu.Unlock()
// No need to attach the underlying channel.Endpoint, since we hijack
// InjectInbound.
e.dispatcher = dispatcher
}

// IsAttached implements stack.LinkEndpoint.IsAttached.
func (e *protectedLinkEndpoint) IsAttached() bool {
e.mu.RLock()
defer e.mu.RUnlock()
return e.dispatcher != nil
}

var _ stack.LinkEndpoint = (*protectedLinkEndpoint)(nil)