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| author |   Stanislav Fomichev <sdf@google.com> | 2019-07-25 15:52:26 -0700 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2019-07-25 18:00:41 -0700 |
| commit | 1ac6b126dbe8108c1fe6e29d023a0f2989cd3fea (patch) | |
| tree | 26829d01b35fb65cb2796d2e4effb3c941a4c77e /Documentation/bpf | |
| parent | bpf/flow_dissector: pass input flags to BPF flow dissector program (diff) | |
| download | wireguard-linux-1ac6b126dbe8108c1fe6e29d023a0f2989cd3fea.tar.xz wireguard-linux-1ac6b126dbe8108c1fe6e29d023a0f2989cd3fea.zip | |
bpf/flow_dissector: document flags
Describe what each input flag does and who uses it.
Acked-by: Petar Penkov <ppenkov@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Petar Penkov <ppenkov@google.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'Documentation/bpf')
| -rw-r--r-- | Documentation/bpf/prog_flow_dissector.rst | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/bpf/prog_flow_dissector.rst b/Documentation/bpf/prog_flow_dissector.rst index ed343abe541e..a78bf036cadd 100644 --- a/Documentation/bpf/prog_flow_dissector.rst +++ b/Documentation/bpf/prog_flow_dissector.rst @@ -26,6 +26,7 @@ The inputs are: * ``nhoff`` - initial offset of the networking header * ``thoff`` - initial offset of the transport header, initialized to nhoff * ``n_proto`` - L3 protocol type, parsed out of L2 header + * ``flags`` - optional flags Flow dissector BPF program should fill out the rest of the ``struct bpf_flow_keys`` fields. Input arguments ``nhoff/thoff/n_proto`` should be @@ -101,6 +102,23 @@ can be called for both cases and would have to be written carefully to handle both cases. +Flags +===== + +``flow_keys->flags`` might contain optional input flags that work as follows: + +* ``BPF_FLOW_DISSECTOR_F_PARSE_1ST_FRAG`` - tells BPF flow dissector to + continue parsing first fragment; the default expected behavior is that + flow dissector returns as soon as it finds out that the packet is fragmented; + used by ``eth_get_headlen`` to estimate length of all headers for GRO. +* ``BPF_FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL`` - tells BPF flow dissector to + stop parsing as soon as it reaches IPv6 flow label; used by + ``___skb_get_hash`` and ``__skb_get_hash_symmetric`` to get flow hash. +* ``BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP`` - tells BPF flow dissector to stop + parsing as soon as it reaches encapsulated headers; used by routing + infrastructure. + + Reference Implementation ======================== |