link: add Info() method to all link types

link/cgroup.go

@@ -6,6 +6,7 @@ import (
 	"os"
 
 	"github.com/cilium/ebpf"
+	"github.com/cilium/ebpf/internal/sys"
 )
 
 type cgroupAttachFlags uint32
@@ -187,3 +188,21 @@ func newLinkCgroup(cgroup *os.File, attach ebpf.AttachType, prog *ebpf.Program)
 
 	return &linkCgroup{*link}, err
 }
+
+func (cg *linkCgroup) Info() (*Info, error) {
+	var info sys.CgroupLinkInfo
+	if err := sys.ObjInfo(cg.fd, &info); err != nil {
+		return nil, fmt.Errorf("cgroup link info: %s", err)
+	}
+	extra := &CgroupInfo{
+		CgroupId:   info.CgroupId,
+		AttachType: info.AttachType,
+	}
+
+	return &Info{
+		info.Type,
+		info.Id,
+		ebpf.ProgramID(info.ProgId),
+		extra,
+	}, nil
+}

link/kprobe_multi.go

@@ -138,6 +138,25 @@ func (kml *kprobeMultiLink) Unpin() error {
 	return fmt.Errorf("unpin kprobe_multi: %w", ErrNotSupported)
 }
 
+func (kml *kprobeMultiLink) Info() (*Info, error) {
+	var info sys.KprobeMultiLinkInfo
+	if err := sys.ObjInfo(kml.fd, &info); err != nil {
+		return nil, fmt.Errorf("kprobe multi link info: %s", err)
+	}
+	extra := &KprobeMultiInfo{
+		count:  info.Count,
+		flags:  info.Flags,
+		missed: info.Missed,
+	}
+
+	return &Info{
+		info.Type,
+		info.Id,
+		ebpf.ProgramID(info.ProgId),
+		extra,
+	}, nil
+}
+
 var haveBPFLinkKprobeMulti = internal.NewFeatureTest("bpf_link_kprobe_multi", "5.18", func() error {
 	prog, err := ebpf.NewProgram(&ebpf.ProgramSpec{
 		Name: "probe_kpm_link",

link/link.go

@@ -126,6 +126,8 @@ func wrapRawLink(raw *RawLink) (_ Link, err error) {
 		return &netfilterLink{*raw}, nil
 	case NetkitType:
 		return &netkitLink{*raw}, nil
+	case XDPType:
+		return &xdpLink{*raw}, nil
 	default:
 		return raw, nil
 	}
@@ -438,124 +440,21 @@ func (l *RawLink) UpdateArgs(opts RawLinkUpdateOptions) error {
 }
 
 // Info returns metadata about the link.
+//
+// Linktype specific metadata is not included and can be retrieved
+// via the linktype specific Info() method.
 func (l *RawLink) Info() (*Info, error) {
 	var info sys.LinkInfo
 
 	if err := sys.ObjInfo(l.fd, &info); err != nil {
 		return nil, fmt.Errorf("link info: %s", err)
 	}
 
-	var extra interface{}
-	switch info.Type {
-	case CgroupType:
-		var cgroupInfo sys.CgroupLinkInfo
-		if err := sys.ObjInfo(l.fd, &cgroupInfo); err != nil {
-			return nil, fmt.Errorf("cgroup link info: %s", err)
-		}
-		extra = &CgroupInfo{
-			CgroupId:   cgroupInfo.CgroupId,
-			AttachType: cgroupInfo.AttachType,
-		}
-	case NetNsType:
-		var netnsInfo sys.NetNsLinkInfo
-		if err := sys.ObjInfo(l.fd, &netnsInfo); err != nil {
-			return nil, fmt.Errorf("netns link info: %s", err)
-		}
-		extra = &NetNsInfo{
-			NetnsIno:   netnsInfo.NetnsIno,
-			AttachType: netnsInfo.AttachType,
-		}
-	case TracingType:
-		var tracingInfo sys.TracingLinkInfo
-		if err := sys.ObjInfo(l.fd, &tracingInfo); err != nil {
-			return nil, fmt.Errorf("tracing link info: %s", err)
-		}
-		extra = &TracingInfo{
-			TargetObjId: tracingInfo.TargetObjId,
-			TargetBtfId: tracingInfo.TargetBtfId,
-			AttachType:  tracingInfo.AttachType,
-		}
-	case XDPType:
-		var xdpInfo sys.XDPLinkInfo
-		if err := sys.ObjInfo(l.fd, &xdpInfo); err != nil {
-			return nil, fmt.Errorf("xdp link info: %s", err)
-		}
-		extra = &XDPInfo{
-			Ifindex: xdpInfo.Ifindex,
-		}
-	case RawTracepointType, IterType, UprobeMultiType:
-		// Extra metadata not supported.
-	case TCXType:
-		var tcxInfo sys.TcxLinkInfo
-		if err := sys.ObjInfo(l.fd, &tcxInfo); err != nil {
-			return nil, fmt.Errorf("tcx link info: %s", err)
-		}
-		extra = &TCXInfo{
-			Ifindex:    tcxInfo.Ifindex,
-			AttachType: tcxInfo.AttachType,
-		}
-	case NetfilterType:
-		var netfilterInfo sys.NetfilterLinkInfo
-		if err := sys.ObjInfo(l.fd, &netfilterInfo); err != nil {
-			return nil, fmt.Errorf("netfilter link info: %s", err)
-		}
-		extra = &NetfilterInfo{
-			Pf:       netfilterInfo.Pf,
-			Hooknum:  netfilterInfo.Hooknum,
-			Priority: netfilterInfo.Priority,
-			Flags:    netfilterInfo.Flags,
-		}
-	case NetkitType:
-		var netkitInfo sys.NetkitLinkInfo
-		if err := sys.ObjInfo(l.fd, &netkitInfo); err != nil {
-			return nil, fmt.Errorf("tcx link info: %s", err)
-		}
-		extra = &NetkitInfo{
-			Ifindex:    netkitInfo.Ifindex,
-			AttachType: netkitInfo.AttachType,
-		}
-	case KprobeMultiType:
-		var kprobeMultiInfo sys.KprobeMultiLinkInfo
-		if err := sys.ObjInfo(l.fd, &kprobeMultiInfo); err != nil {
-			return nil, fmt.Errorf("kprobe multi link info: %s", err)
-		}
-		extra = &KprobeMultiInfo{
-			count:  kprobeMultiInfo.Count,
-			flags:  kprobeMultiInfo.Flags,
-			missed: kprobeMultiInfo.Missed,
-		}
-	case PerfEventType:
-		var perfEventInfo sys.PerfEventLinkInfo
-		if err := sys.ObjInfo(l.fd, &perfEventInfo); err != nil {
-			return nil, fmt.Errorf("perf event link info: %s", err)
-		}
-
-		var extra2 interface{}
-		switch perfEventInfo.PerfEventType {
-		case sys.BPF_PERF_EVENT_KPROBE, sys.BPF_PERF_EVENT_KRETPROBE:
-			var kprobeInfo sys.KprobeLinkInfo
-			if err := sys.ObjInfo(l.fd, &kprobeInfo); err != nil {
-				return nil, fmt.Errorf("kprobe multi link info: %s", err)
-			}
-			extra2 = &KprobeInfo{
-				address: kprobeInfo.Addr,
-				missed:  kprobeInfo.Missed,
-			}
-		}
-
-		extra = &PerfEventInfo{
-			Type:  perfEventInfo.PerfEventType,
-			extra: extra2,
-		}
-	default:
-		return nil, fmt.Errorf("unknown link info type: %d", info.Type)
-	}
-
 	return &Info{
 		info.Type,
 		info.Id,
 		ebpf.ProgramID(info.ProgId),
-		extra,
+		nil,
 	}, nil
 }
 

link/netfilter.go

@@ -67,4 +67,24 @@ func (*netfilterLink) Update(new *ebpf.Program) error {
 	return fmt.Errorf("netfilter update: %w", ErrNotSupported)
 }
 
+func (nf *netfilterLink) Info() (*Info, error) {
+	var info sys.NetfilterLinkInfo
+	if err := sys.ObjInfo(nf.fd, &info); err != nil {
+		return nil, fmt.Errorf("netfilter link info: %s", err)
+	}
+	extra := &NetfilterInfo{
+		Pf:       info.Pf,
+		Hooknum:  info.Hooknum,
+		Priority: info.Priority,
+		Flags:    info.Flags,
+	}
+
+	return &Info{
+		info.Type,
+		info.Id,
+		ebpf.ProgramID(info.ProgId),
+		extra,
+	}, nil
+}
+
 var _ Link = (*netfilterLink)(nil)

link/netkit.go

@@ -69,3 +69,21 @@ type netkitLink struct {
 }
 
 var _ Link = (*netkitLink)(nil)
+
+func (netkit *netkitLink) Info() (*Info, error) {
+	var info sys.NetkitLinkInfo
+	if err := sys.ObjInfo(netkit.fd, &info); err != nil {
+		return nil, fmt.Errorf("netkit link info: %s", err)
+	}
+	extra := &NetkitInfo{
+		Ifindex:    info.Ifindex,
+		AttachType: info.AttachType,
+	}
+
+	return &Info{
+		info.Type,
+		info.Id,
+		ebpf.ProgramID(info.ProgId),
+		extra,
+	}, nil
+}

link/netns.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"github.com/cilium/ebpf"
+	"github.com/cilium/ebpf/internal/sys"
 )
 
 // NetNsLink is a program attached to a network namespace.
@@ -34,3 +35,21 @@ func AttachNetNs(ns int, prog *ebpf.Program) (*NetNsLink, error) {
 
 	return &NetNsLink{*link}, nil
 }
+
+func (ns *NetNsLink) Info() (*Info, error) {
+	var info sys.NetNsLinkInfo
+	if err := sys.ObjInfo(ns.fd, &info); err != nil {
+		return nil, fmt.Errorf("netns link info: %s", err)
+	}
+	extra := &NetNsInfo{
+		NetnsIno:   info.NetnsIno,
+		AttachType: info.AttachType,
+	}
+
+	return &Info{
+		info.Type,
+		info.Id,
+		ebpf.ProgramID(info.ProgId),
+		extra,
+	}, nil
+}

link/perf_event.go

@@ -144,6 +144,38 @@ func (pl *perfEventLink) PerfEvent() (*os.File, error) {
 	return fd.File("perf-event"), nil
 }
 
+func (pl *perfEventLink) Info() (*Info, error) {
+	var info sys.PerfEventLinkInfo
+	if err := sys.ObjInfo(pl.fd, &info); err != nil {
+		return nil, fmt.Errorf("perf event link info: %s", err)
+	}
+
+	var extra2 interface{}
+	switch info.PerfEventType {
+	case sys.BPF_PERF_EVENT_KPROBE, sys.BPF_PERF_EVENT_KRETPROBE:
+		var kprobeInfo sys.KprobeLinkInfo
+		if err := sys.ObjInfo(pl.fd, &kprobeInfo); err != nil {
+			return nil, fmt.Errorf("kprobe link info: %s", err)
+		}
+		extra2 = &KprobeInfo{
+			address: kprobeInfo.Addr,
+			missed:  kprobeInfo.Missed,
+		}
+	}
+
+	extra := &PerfEventInfo{
+		Type:  info.PerfEventType,
+		extra: extra2,
+	}
+
+	return &Info{
+		info.Type,
+		info.Id,
+		ebpf.ProgramID(info.ProgId),
+		extra,
+	}, nil
+}
+
 // perfEventIoctl implements Link and handles the perf event lifecycle
 // via ioctl().
 type perfEventIoctl struct {

link/tcx.go

@@ -69,3 +69,21 @@ type tcxLink struct {
 }
 
 var _ Link = (*tcxLink)(nil)
+
+func (tcx *tcxLink) Info() (*Info, error) {
+	var info sys.TcxLinkInfo
+	if err := sys.ObjInfo(tcx.fd, &info); err != nil {
+		return nil, fmt.Errorf("tcx link info: %s", err)
+	}
+	extra := &TCXInfo{
+		Ifindex:    info.Ifindex,
+		AttachType: info.AttachType,
+	}
+
+	return &Info{
+		info.Type,
+		info.Id,
+		ebpf.ProgramID(info.ProgId),
+		extra,
+	}, nil
+}

link/tracing.go

@@ -18,6 +18,25 @@ func (f *tracing) Update(new *ebpf.Program) error {
 	return fmt.Errorf("tracing update: %w", ErrNotSupported)
 }
 
+func (f *tracing) Info() (*Info, error) {
+	var info sys.TracingLinkInfo
+	if err := sys.ObjInfo(f.fd, &info); err != nil {
+		return nil, fmt.Errorf("tracing link info: %s", err)
+	}
+	extra := &TracingInfo{
+		TargetObjId: info.TargetObjId,
+		TargetBtfId: info.TargetBtfId,
+		AttachType:  info.AttachType,
+	}
+
+	return &Info{
+		info.Type,
+		info.Id,
+		ebpf.ProgramID(info.ProgId),
+		extra,
+	}, nil
+}
+
 // AttachFreplace attaches the given eBPF program to the function it replaces.
 //
 // The program and name can either be provided at link time, or can be provided

link/xdp.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"github.com/cilium/ebpf"
+	"github.com/cilium/ebpf/internal/sys"
 )
 
 // XDPAttachFlags represents how XDP program will be attached to interface.
@@ -50,5 +51,26 @@ func AttachXDP(opts XDPOptions) (Link, error) {
 		Flags:   uint32(opts.Flags),
 	})
 
-	return rawLink, err
+	return &xdpLink{*rawLink}, err
+}
+
+type xdpLink struct {
+	RawLink
+}
+
+func (xdp *xdpLink) Info() (*Info, error) {
+	var info sys.XDPLinkInfo
+	if err := sys.ObjInfo(xdp.fd, &info); err != nil {
+		return nil, fmt.Errorf("xdp link info: %s", err)
+	}
+	extra := &XDPInfo{
+		Ifindex: info.Ifindex,
+	}
+
+	return &Info{
+		info.Type,
+		info.Id,
+		ebpf.ProgramID(info.ProgId),
+		extra,
+	}, nil
 }