[net-next v4 0/8] seg6: add support for SRv6 End.DT4/DT6 behavior

[Andrea Mayer]

This patchset provides support for the SRv6 End.DT4 and End.DT6 (VRF mode)
behaviors.

The SRv6 End.DT4 behavior is used to implement multi-tenant IPv4 L3 VPNs. It
decapsulates the received packets and performs IPv4 routing lookup in the
routing table of the tenant. The SRv6 End.DT4 Linux implementation leverages a
VRF device in order to force the routing lookup into the associated routing
table.
The SRv6 End.DT4 behavior is defined in the SRv6 Network Programming [1].

The Linux kernel already offers an implementation of the SRv6 End.DT6 behavior
which allows us to set up IPv6 L3 VPNs over SRv6 networks. This new
implementation of DT6 is based on the same VRF infrastructure already exploited
for implementing the SRv6 End.DT4 behavior. The aim of the new SRv6 End.DT6 in
VRF mode consists in simplifying the construction of IPv6 L3 VPN services in
the multi-tenant environment.
Currently, the two SRv6 End.DT6 implementations (legacy and VRF mode)
coexist seamlessly and can be chosen according to the context and the user
preferences.

- Patch 1 is needed to solve a pre-existing issue with tunneled packets
  when a sniffer is attached;

- Patch 2 improves the management of the seg6local attributes used by the
  SRv6 behaviors;

- Patch 3 adds support for optional attributes in SRv6 behaviors;

- Patch 4 introduces two callbacks used for customizing the
  creation/destruction of a SRv6 behavior;

- Patch 5 is the core patch that adds support for the SRv6 End.DT4
  behavior;

- Patch 6 introduces the VRF support for SRv6 End.DT6 behavior;

- Patch 7 adds the selftest for SRv6 End.DT4 behavior;

- Patch 8 adds the selftest for SRv6 End.DT6 (VRF mode) behavior.

Regarding iproute2, the support for the new "vrftable" attribute, required by
both SRv6 End.DT4 and End.DT6 (VRF mode) behaviors, is provided in a different
patchset that will follow shortly.

I would like to thank David Ahern for his support during the development of
this patchset.

Comments, suggestions and improvements are very welcome!

Thanks,
Andrea Mayer

v4
 seg6: add support for the SRv6 End.DT4 behavior
  - remove IS_ERR() checks in cmp_nla_vrftable(), thanks to Jakub Kicinski.

 remove patch for iproute2:
  - mixing the iproute2 patch with this patchset confused patchwork.

v3
 notes about the build bot:
  - apparently the ',' (comma) in the subject prefix confused the build bot.
    Removed the ',' in favor of ' ' (space). 
    
    Thanks to David Ahern and Konstantin Ryabitsev for shedding light on this
    fact.
    Thanks also to Nathan Chancellor for trying to build the patchset v2 by
    simulating the bot issue.

 add new patch for iproute2:
  - [9/9] seg6: add support for vrftable attribute in End.DT4/DT6 behaviors

 add new patch:
  -  [8/9] selftests: add selftest for the SRv6 End.DT6 (VRF) behavior

 add new patch:
  - [6/9] seg6: add VRF support for SRv6 End.DT6 behavior

 add new patch:
  - [3/9] seg6: add support for optional attributes in SRv6 behaviors

 selftests: add selftest for the SRv6 End.DT4 behavior
  - keep David Ahern's review tag since the code wasn't changed. Thanks to David  
    Ahern for his review.

 seg6: add support for the SRv6 End.DT4 behavior
  - remove useless error in seg6_end_dt4_build();
  - remove #ifdef/#endif stubs for DT4 when CONFIG_NET_L3_MASTER_DEV is not
    defined;
  - fix coding style.

    Thanks to Jakub Kicinski for his review and for all his suggestions.

 seg6: add callbacks for customizing the creation/destruction of a behavior
  - remove typedef(s) slwt_{build/destroy}_state_t;
  - fix coding style: remove empty lines, trivial comments and rename labels in
    the seg6_local_build_state() function.
    
    Thanks to Jakub Kicinski for his review and for all his suggestions.

 seg6: improve management of behavior attributes
  - remove defensive programming approach in destroy_attr_srh(),
    destroy_attr_bpf() and destroy_attrs();
  - change the __destroy_attrs() function signature, renaming the 'end' argument    
    'parsed_max'. Now, the __destroy_attrs() keeps only the 'parsed_max' and
    'slwt' arguments.
    
    Thanks to Jakub Kicinski for his review and for all his suggestions.

 vrf: add mac header for tunneled packets when sniffer is attached
  - keep David Ahern's review tag since the code wasn't changed. 
    
    Thanks to Jakub Kicinski for pointing it out and David Ahern for his review.

v2
 no changes made: resubmitted after false build report.

v1
 improve comments;

 add new patch 2/5 titled: seg6: improve management of behavior attributes

 seg6: add support for the SRv6 End.DT4 behavior
  - remove the inline keyword in the definition of fib6_config_get_net().

 selftests: add selftest for the SRv6 End.DT4 behavior
  - add check for the vrf sysctl

[1] https://tools.ietf.org/html/draft-ietf-spring-srv6-network-programming

Andrea Mayer (8):
  vrf: add mac header for tunneled packets when sniffer is attached
  seg6: improve management of behavior attributes
  seg6: add support for optional attributes in SRv6 behaviors
  seg6: add callbacks for customizing the creation/destruction of a
    behavior
  seg6: add support for the SRv6 End.DT4 behavior
  seg6: add VRF support for SRv6 End.DT6 behavior
  selftests: add selftest for the SRv6 End.DT4 behavior
  selftests: add selftest for the SRv6 End.DT6 (VRF) behavior

 drivers/net/vrf.c                             |  78 ++-
 include/uapi/linux/seg6_local.h               |   1 +
 net/ipv6/seg6_local.c                         | 590 +++++++++++++++++-
 .../selftests/net/srv6_end_dt4_l3vpn_test.sh  | 494 +++++++++++++++
 .../selftests/net/srv6_end_dt6_l3vpn_test.sh  | 502 +++++++++++++++
 5 files changed, 1646 insertions(+), 19 deletions(-)
 create mode 100755 tools/testing/selftests/net/srv6_end_dt4_l3vpn_test.sh
 create mode 100755 tools/testing/selftests/net/srv6_end_dt6_l3vpn_test.sh

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2.20.1