Add sockmap support #179
Add sockmap support #179
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dippynark
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elf/elf.go
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| @@ -555,6 +555,7 @@ func (b *Module) Load(parameters map[string]SectionParams) error { | |||
| isTracepoint := strings.HasPrefix(secName, "tracepoint/") | |||
| isSchedCls := strings.HasPrefix(secName, "sched_cls/") | |||
| isSchedAct := strings.HasPrefix(secName, "sched_act/") | |||
| isSkSkb := strings.HasPrefix(secName, "sk/skb/") | |||
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gobpf and libbpf unfortunately diverged in the way they name sections:
https://github.com/torvalds/linux/blob/v5.0/tools/lib/bpf/libbpf.c#L2610-L2662
But when possible, could we adopt the same section names as in libbpf? That would be:
sk_skb/stream_parsersk_skb/stream_verdict
| @@ -133,4 +140,16 @@ int socket__dummy(struct __sk_buff *skb) | |||
| return 0; | |||
| } | |||
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| SEC("sk/skb/parser/dummy_sockmap") | |||
| int parser_dummy(struct __sk_buff *skb) | |||
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The parameter should be struct sk_msg_md *msg.
Ditto in verdict_dummy.
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I think struct __sk_buff * is correct:
- https://github.com/torvalds/linux/blob/master/tools/testing/selftests/bpf/progs/sockmap_parse_prog.c#L16
- https://elixir.bootlin.com/linux/v4.18/source/kernel/bpf/sockmap.c#L1497
and the verifier converts references to struct __sk_buff * fields to the real struct sk_buff * at load time. Maybe I'm missing something?
tests/dummy.c
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| @@ -81,6 +81,13 @@ struct bpf_map_def SEC("maps/dummy_array_custom") dummy_array_custom = { | |||
| .pinning = PIN_CUSTOM_NS, | |||
| }; | |||
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| struct bpf_map_def SEC("maps/dummy_sockmap") sock_map = { | |||
| .type = BPF_MAP_TYPE_SOCKMAP, | |||
| .key_size = sizeof(int), | |||
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Does it worth giving a more realistic key struct? Such as:
struct sock_key {
__u32 sip4;
__u32 dip4;
__u32 sport;
__u32 dport;
};
More complex example on:
https://github.com/cilium/cilium/blob/506bd14/bpf/sockops/bpf_sockops.h#L21-L46
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agreed, have added your example
Adds support for attaching parser and redirect programs to sockmaps. This fixes #177