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authorDavid S. Miller <davem@davemloft.net>2019-04-22 21:35:55 -0700
committerDavid S. Miller <davem@davemloft.net>2019-04-22 21:35:55 -0700
commit2843ba2ec75948e274d2c4f0a9390980e68a6461 (patch)
treeb2fde70246956609ac43ad62026a4fdb48e33fbc /Documentation/networking
parentbe659b8d3c79afc54e087ebf8d849685d7b0d395 (diff)
parentf79b464fd6b56b6256de43bc4c7d5968c0e52968 (diff)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Alexei Starovoitov says: ==================== pull-request: bpf-next 2019-04-22 The following pull-request contains BPF updates for your *net-next* tree. The main changes are: 1) allow stack/queue helpers from more bpf program types, from Alban. 2) allow parallel verification of root bpf programs, from Alexei. 3) introduce bpf sysctl hook for trusted root cases, from Andrey. 4) recognize var/datasec in btf deduplication, from Andrii. 5) cpumap performance optimizations, from Jesper. 6) verifier prep for alu32 optimization, from Jiong. 7) libbpf xsk cleanup, from Magnus. 8) other various fixes and cleanups. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/bpf_flow_dissector.rst126
-rw-r--r--Documentation/networking/index.rst1
2 files changed, 0 insertions, 127 deletions
diff --git a/Documentation/networking/bpf_flow_dissector.rst b/Documentation/networking/bpf_flow_dissector.rst
deleted file mode 100644
index b375ae2ec2c4..000000000000
--- a/Documentation/networking/bpf_flow_dissector.rst
+++ /dev/null
@@ -1,126 +0,0 @@
-.. SPDX-License-Identifier: GPL-2.0
-
-==================
-BPF Flow Dissector
-==================
-
-Overview
-========
-
-Flow dissector is a routine that parses metadata out of the packets. It's
-used in the various places in the networking subsystem (RFS, flow hash, etc).
-
-BPF flow dissector is an attempt to reimplement C-based flow dissector logic
-in BPF to gain all the benefits of BPF verifier (namely, limits on the
-number of instructions and tail calls).
-
-API
-===
-
-BPF flow dissector programs operate on an ``__sk_buff``. However, only the
-limited set of fields is allowed: ``data``, ``data_end`` and ``flow_keys``.
-``flow_keys`` is ``struct bpf_flow_keys`` and contains flow dissector input
-and output arguments.
-
-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
-
-Flow dissector BPF program should fill out the rest of the ``struct
-bpf_flow_keys`` fields. Input arguments ``nhoff/thoff/n_proto`` should be
-also adjusted accordingly.
-
-The return code of the BPF program is either BPF_OK to indicate successful
-dissection, or BPF_DROP to indicate parsing error.
-
-__sk_buff->data
-===============
-
-In the VLAN-less case, this is what the initial state of the BPF flow
-dissector looks like::
-
- +------+------+------------+-----------+
- | DMAC | SMAC | ETHER_TYPE | L3_HEADER |
- +------+------+------------+-----------+
- ^
- |
- +-- flow dissector starts here
-
-
-.. code:: c
-
- skb->data + flow_keys->nhoff point to the first byte of L3_HEADER
- flow_keys->thoff = nhoff
- flow_keys->n_proto = ETHER_TYPE
-
-In case of VLAN, flow dissector can be called with the two different states.
-
-Pre-VLAN parsing::
-
- +------+------+------+-----+-----------+-----------+
- | DMAC | SMAC | TPID | TCI |ETHER_TYPE | L3_HEADER |
- +------+------+------+-----+-----------+-----------+
- ^
- |
- +-- flow dissector starts here
-
-.. code:: c
-
- skb->data + flow_keys->nhoff point the to first byte of TCI
- flow_keys->thoff = nhoff
- flow_keys->n_proto = TPID
-
-Please note that TPID can be 802.1AD and, hence, BPF program would
-have to parse VLAN information twice for double tagged packets.
-
-
-Post-VLAN parsing::
-
- +------+------+------+-----+-----------+-----------+
- | DMAC | SMAC | TPID | TCI |ETHER_TYPE | L3_HEADER |
- +------+------+------+-----+-----------+-----------+
- ^
- |
- +-- flow dissector starts here
-
-.. code:: c
-
- skb->data + flow_keys->nhoff point the to first byte of L3_HEADER
- flow_keys->thoff = nhoff
- flow_keys->n_proto = ETHER_TYPE
-
-In this case VLAN information has been processed before the flow dissector
-and BPF flow dissector is not required to handle it.
-
-
-The takeaway here is as follows: BPF flow dissector program can be called with
-the optional VLAN header and should gracefully handle both cases: when single
-or double VLAN is present and when it is not present. The same program
-can be called for both cases and would have to be written carefully to
-handle both cases.
-
-
-Reference Implementation
-========================
-
-See ``tools/testing/selftests/bpf/progs/bpf_flow.c`` for the reference
-implementation and ``tools/testing/selftests/bpf/flow_dissector_load.[hc]``
-for the loader. bpftool can be used to load BPF flow dissector program as well.
-
-The reference implementation is organized as follows:
- * ``jmp_table`` map that contains sub-programs for each supported L3 protocol
- * ``_dissect`` routine - entry point; it does input ``n_proto`` parsing and
- does ``bpf_tail_call`` to the appropriate L3 handler
-
-Since BPF at this point doesn't support looping (or any jumping back),
-jmp_table is used instead to handle multiple levels of encapsulation (and
-IPv6 options).
-
-
-Current Limitations
-===================
-BPF flow dissector doesn't support exporting all the metadata that in-kernel
-C-based implementation can export. Notable example is single VLAN (802.1Q)
-and double VLAN (802.1AD) tags. Please refer to the ``struct bpf_flow_keys``
-for a set of information that's currently can be exported from the BPF context.
diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst
index 269d6f2661d5..f390fe3cfdfb 100644
--- a/Documentation/networking/index.rst
+++ b/Documentation/networking/index.rst
@@ -9,7 +9,6 @@ Contents:
netdev-FAQ
af_xdp
batman-adv
- bpf_flow_dissector
can
can_ucan_protocol
device_drivers/freescale/dpaa2/index