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Collect and output skb->cb when --filter-trace-tc #461

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merged 1 commit into from
Dec 5, 2024
+31 −3
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Collect and output skb->cb when --filter-trace-tc #461

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10 changes: 8 additions & 2 deletions bpf/kprobe_pwru.c
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Original file line number Diff line number Diff line change
Expand Up @@ -54,7 +54,7 @@ struct skb_meta {
u32 len;
u32 mtu;
u16 protocol;
u16 pad;
u32 cb[5];
} __attribute__((packed));

struct tuple {
Expand Down Expand Up @@ -143,7 +143,8 @@ struct config {
u8 output_shinfo: 1;
u8 output_stack: 1;
u8 output_caller: 1;
u8 output_unused: 2;
u8 output_cb: 1;
u8 output_unused: 1;
u8 is_set: 1;
u8 track_skb: 1;
u8 track_skb_by_stackid: 1;
Expand Down Expand Up @@ -443,6 +444,11 @@ set_output(void *ctx, struct sk_buff *skb, struct event_t *event) {
if (cfg->output_stack) {
event->print_stack_id = bpf_get_stackid(ctx, &print_stack_map, BPF_F_FAST_STACK_CMP);
}

if (cfg->output_cb) {
struct qdisc_skb_cb *cb = (struct qdisc_skb_cb *)&skb->cb;
bpf_probe_read_kernel(&event->meta.cb, sizeof(event->meta.cb), (void *)&cb->data);
}
}

static __noinline bool
Expand Down
4 changes: 4 additions & 0 deletions internal/pwru/config.go
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ const (
OutputShinfoMask
OutputStackMask
OutputCallerMask
OutputCbMask
)

const (
Expand Down Expand Up @@ -69,6 +70,9 @@ func GetConfig(flags *Flags) (cfg FilterCfg, err error) {
if flags.OutputCaller {
cfg.OutputFlags |= OutputCallerMask
}
if flags.FilterTraceTc {
cfg.OutputFlags |= OutputCbMask
}
if flags.FilterTrackSkb {
cfg.FilterFlags |= TrackSkbMask
}
Expand Down
18 changes: 18 additions & 0 deletions internal/pwru/output.go
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Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,7 @@ type jsonPrinter struct {
Proto uint16 `json:"proto,omitempty"`
Mtu uint32 `json:"mtu,omitempty"`
Len uint32 `json:"len,omitempty"`
Cb [5]uint32 `json:"cb,omitempty"`
Tuple *jsonTuple `json:"tuple,omitempty"`
Stack interface{} `json:"stack,omitempty"`
SkbMetadata interface{} `json:"skb_metadata,omitempty"`
Expand Down Expand Up @@ -141,6 +142,9 @@ func (o *output) PrintHeader() {
}
if o.flags.OutputMeta {
fmt.Fprintf(o.writer, " %-10s %-8s %16s %-6s %-5s %-5s", "NETNS", "MARK/x", centerAlignString("IFACE", 16), "PROTO", "MTU", "LEN")
if o.flags.FilterTraceTc {
fmt.Fprintf(o.writer, " %-56s", "__sk_buff->cb[]")
}
}
if o.flags.OutputTuple {
fmt.Fprintf(o.writer, " %s", "TUPLE")
Expand Down Expand Up @@ -187,6 +191,9 @@ func (o *output) PrintJson(event *Event) {
d.Proto = byteorder.NetworkToHost16(event.Meta.Proto)
d.Mtu = event.Meta.MTU
d.Len = event.Meta.Len
if o.flags.FilterTraceTc {
d.Cb = event.Meta.Cb
}
}

if o.flags.OutputTuple {
Expand Down Expand Up @@ -330,6 +337,14 @@ func getMetaData(event *Event, o *output) (metaData string) {
return metaData
}

func getCb(event *Event) (cb string) {
res := []string{}
for _, val := range event.Meta.Cb {
res = append(res, fmt.Sprintf("0x%08X", val))
}
return fmt.Sprintf("[%s]", strings.Join(res, ","))
}

func getOutFuncName(o *output, event *Event, addr uint64) string {
var funcName string

Expand Down Expand Up @@ -410,6 +425,9 @@ func (o *output) Print(event *Event) {

if o.flags.OutputMeta {
fmt.Fprintf(o.writer, " %s", getMetaData(event, o))
if o.flags.FilterTraceTc {
fmt.Fprintf(o.writer, " %s", getCb(event))
}
}

if o.flags.OutputTuple {
Expand Down
2 changes: 1 addition & 1 deletion internal/pwru/types.go
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Original file line number Diff line number Diff line change
Expand Up @@ -130,7 +130,7 @@ type Meta struct {
Len uint32
MTU uint32
Proto uint16
Pad uint16
Cb [5]uint32
}

type StackData struct {
Expand Down
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