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derp/xdp: retain the link so that the fd is not closed

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BPF links require that the owning FD remains open, this FD is embedded
into the RawLink returned by the attach function and must live for the
duration of the server.

Updates ENG-4274

Signed-off-by: James Tucker <james@tailscale.com>
This commit is contained in:
James Tucker 2024-06-28 14:26:55 -07:00 committed by James Tucker
parent b565a9faa7
commit 114d1caf55
1 changed files with 10 additions and 2 deletions
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12
derp/xdp/xdp_linux.go
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@ -14,6 +14,7 @@ import (
"github.com/cilium/ebpf"
"github.com/cilium/ebpf/link"
"github.com/prometheus/client_golang/prometheus"
"tailscale.com/util/multierr"
)
//go:generate go run github.com/cilium/ebpf/cmd/bpf2go -type config -type counters_key -type counter_key_af -type counter_key_packets_bytes_action -type counter_key_prog_end bpf xdp.c -- -I headers
@ -27,6 +28,7 @@ type STUNServer struct {
metrics *stunServerMetrics
dstPort int
dropSTUN bool
link link.Link
}
//lint:ignore U1000 used in xdp_linux_test.go, which has a build tag
@ -87,7 +89,7 @@ func NewSTUNServer(config *STUNServerConfig, opts ...STUNServerOption) (*STUNSer
if err != nil {
return nil, fmt.Errorf("error finding device: %w", err)
}
_, err = link.AttachXDP(link.XDPOptions{
link, err := link.AttachXDP(link.XDPOptions{
Program: objs.XdpProgFunc,
Interface: iface.Index,
Flags: link.XDPAttachFlags(config.AttachFlags),
@ -95,6 +97,7 @@ func NewSTUNServer(config *STUNServerConfig, opts ...STUNServerOption) (*STUNSer
if err != nil {
return nil, fmt.Errorf("error attaching XDP program to dev: %w", err)
}
server.link = link
return server, nil
}
@ -102,7 +105,12 @@ func NewSTUNServer(config *STUNServerConfig, opts ...STUNServerOption) (*STUNSer
func (s *STUNServer) Close() error {
s.mu.Lock()
defer s.mu.Unlock()
return s.objs.Close()
var errs []error
if s.link != nil {
errs = append(errs, s.link.Close())
}
errs = append(errs, s.objs.Close())
return multierr.New(errs...)
}
type stunServerMetrics struct {