aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/bpf/prog_flow_dissector.rst
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/bpf/prog_flow_dissector.rst')
-rw-r--r--Documentation/bpf/prog_flow_dissector.rst18
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
========================