[ovs-dev] [PATCHv4 00/11] Add support for connection tracking.

Joe Stringer joestringer at nicira.com
Fri Oct 2 21:16:07 UTC 2015


This series adds support for sending packets through a connection tracker,
which allows OVS to perform stateful firewalling functions. The functionality
added in this series works in conjunction with the interface proposed in the
in the current upstream Linux kernel development release, expected to become
Linux-4.3. The linux datapath backport is not included in the series at this
time, but a work in progress version is made available in a branch (see below).

The functionality is manipulated through a new action "CT" and several new NXM
fields: ct_state, ct_zone, ct_mark, ct_label. The CT action allows these fields
to be populated, and for connections that match the flow to be tracked. Later
patches in the series also allow metadata to be attached to these connections.

When a flow is sent through the connection tracker, there are two common
functions to perform. Firstly, match packets from port 1 and do a lookup:

    ovs-ofctl add-flow br0 "in_port=1,actions=ct(table=1)"

When the table is specified, the ct action forks pipeline processing in two.
The original instance of the packet will continue processing the current
actions list as an untracked packet. An additional instance of the packet will
be sent to the connection tracker, which will be re-injected into the OpenFlow
pipeline to resume processing in the specified table, with the ct_state and
other ct match fields set.

The connection state, as represented in the ct_state field, consists of a
collection of flags, including:
- Tracked (trk): Connection tracking has occurred.
- Reply (rpl): The flow is in the reply direction.
- Invalid (inv): The connection tracker couldn't identify the connection.
- New (new): This is the beginning of a new connection.
- Established (est): This is part of an already existing connection.
- Related (rel): This connection is related to an existing connection.

When the first packets for a new connection are sent through the connection
tracker, the ct_state will have the "+trk+new" flags set. The OpenFlow
controller may specify a policy to match new connections and allow or deny
them.

The second function of the ct action is to "commit" the connections. This
signals to the connection tracker that this connection should be tracked on an
ongoing basis, so that subsequent packets may be identified as belonging to
this connection. For instance, to allow new connections from port 1->2:

    ovs-ofctl add-flow br0 \
        "in_port=1,ip,ct_state=+trk+new,action=ct(commit),2"

Later packets in the connection will have the "+est" flag set, so existing
connections may be allowed as so:

    ovs-ofctl add-flow br0 "in_port=1,ip,ct_state=+trk+est,action=2"

In addition to the above, several other parameters may be provided to the ct
action:
- zone: A 16-bit value or NXM field to retrieve the zone from. Each zone is an
  independent connection tracking context. Connections which are committed to
  zone A will not be remembered in zone B, unless the connection is also
  explicitly committed to zone B.

  eg: actions=ct(zone=1),ct(zone=NXM_NX_REG0[0..15])

- exec: Execute a nested set of actions. This allows additional functions to be
  performed as part of the connection tracking execution. In this series, the
  set_field, reg_move and reg_load actions are supported with two connection
  tracking metadata fields: ct_mark and ct_label. No other actions are
  supported.

  eg: actions=ct(commit,exec(set_field:1->ct_mark))

- alg: Specify an ALG to assist connection tracking. Some protocols consist of
  multiple traffic streams that are impossible to associate without additional
  context. This parameter provides that context to the connection tracker to
  make it possible to track, for instance, FTP data connections.

  eg: actions=ct(commit,alg=ftp)

Further examples are available in the commit messages for each patch, the
ovs-ofctl(8) man pages, and the traffic testsuite in tests/system-traffic.at.

---
This series is also available here with WIP datapath support:
https://github.com/justinpettit/ovs conntrack

---
v4: Reduce duplicate code for parsing ct_labels
    Simplify reg_load for 128-bit fields
    More testing of commandline formatting for fields
    ct_label byte ordering is now consistent with conntrack-tools
    Update for latest proposed interface changes
    Minor bugfixes
    Add several acks
v3: Change label OpenFlow wire format to be128.
    Extend ct_state to 32 bits on the wire (remains 16 bits in flow).
    Expand on ovs-ofctl documentation for ct fields and action.
    Add several new OpenFlow wire-format and formatting tests.
    Handle nested actions parsing with the correct OpenFlow version.
    Tighten corner case error handling.
    Add some new system tests passing packets via the local stack.
v2: Applied patches 1-2.
    Expand NXM_NX_CT_STATE to 16 bits (datapath remains 8 bits).
    Extend interface documentation, particularly in meta-flow and ofp-actions.
    Addressed feedback from v1.
v1: First non-RFC post, based on upstream merged datapath interface.


Andy Zhou (1):
  dpif-netlink: Allow MRU packet attribute.

Joe Stringer (10):
  ofp-actions: Refactor set_field tokenization.
  ofp-actions: Extend reg_load parsing to >64bits.
  types: Add big-endian 128-bit types and helpers.
  meta-flow: Rename IPv6 type to be128.
  ofp-actions: Pass ofp_version to decode functions.
  Add support for connection tracking.
  Add connection tracking mark support.
  Add connection tracking label support.
  Add support for connection tracking helper/ALGs.
  system-traffic: Add ct tests using local stack.

 NEWS                                              |    3 +
 build-aux/extract-ofp-actions                     |    9 +-
 build-aux/extract-ofp-fields                      |    3 +-
 datapath/flow_netlink.c                           |    2 +-
 datapath/linux/compat/include/linux/openvswitch.h |   53 +
 include/openvswitch/types.h                       |   14 +
 include/sparse/netinet/in.h                       |    2 +
 include/windows/netinet/in.h                      |    1 +
 lib/byte-order.h                                  |   14 +
 lib/dpif-netdev.c                                 |   13 +
 lib/dpif-netlink.c                                |    5 +
 lib/dpif.c                                        |    3 +
 lib/dpif.h                                        |    3 +
 lib/flow.c                                        |   79 +-
 lib/flow.h                                        |   29 +-
 lib/match.c                                       |  114 ++-
 lib/match.h                                       |    7 +
 lib/meta-flow.c                                   |  146 +++
 lib/meta-flow.h                                   |  111 +-
 lib/netlink.c                                     |   11 +
 lib/netlink.h                                     |    2 +
 lib/nx-match.c                                    |   26 +-
 lib/odp-execute.c                                 |   10 +
 lib/odp-util.c                                    |  492 +++++++++
 lib/odp-util.h                                    |   16 +-
 lib/ofp-actions.c                                 |  617 +++++++++--
 lib/ofp-actions.h                                 |   50 +
 lib/ofp-parse.c                                   |   15 +
 lib/ofp-parse.h                                   |    1 +
 lib/ofp-util.c                                    |    2 +-
 lib/packets.c                                     |    1 +
 lib/packets.h                                     |   20 +-
 lib/util.h                                        |   30 +
 ofproto/ofproto-dpif-rid.c                        |    2 +
 ofproto/ofproto-dpif-rid.h                        |    3 +-
 ofproto/ofproto-dpif-sflow.c                      |    5 +
 ofproto/ofproto-dpif-upcall.c                     |   17 +-
 ofproto/ofproto-dpif-xlate.c                      |  145 ++-
 ofproto/ofproto-dpif.c                            |   90 ++
 ofproto/ofproto-unixctl.man                       |    8 +
 tests/atlocal.in                                  |   14 +
 tests/automake.mk                                 |    1 +
 tests/dpif-netdev.at                              |    2 +-
 tests/odp.at                                      |   19 +
 tests/ofp-actions.at                              |   49 +
 tests/ofproto-dpif.at                             |    4 +-
 tests/ofproto.at                                  |    6 +-
 tests/ovs-ofctl.at                                |   58 +-
 tests/system-common-macros.at                     |   21 +
 tests/system-kmod-macros.at                       |   16 +
 tests/system-traffic.at                           | 1127 +++++++++++++++++++++
 tests/system-userspace-macros.at                  |    9 +
 tests/test-l7.py                                  |   72 ++
 tests/test-odp.c                                  |    4 +
 utilities/ovs-ofctl.8.in                          |  193 ++++
 55 files changed, 3667 insertions(+), 102 deletions(-)
 create mode 100755 tests/test-l7.py

-- 
2.1.4




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