On 15/05/2022 00:41, Nikolay Aleksandrov wrote:

On 13/05/2022 20:43, Jonathan Toppins wrote:

quoted

Implement a MAC filter that prevents duplicate frame delivery when
handling BUM traffic. This attempts to partially replicate OvS SLB
Bonding[1] like functionality without requiring significant change
in the Linux bridging code.

A typical network setup for this feature would be:

            .--------------------------------------------.
            |         .--------------------.             |
            |         |                    |             |
       .-------------------.               |             |
       |    | Bond 0  |    |               |             |
       | .--'---. .---'--. |               |             |
  .----|-| eth0 |-| eth1 |-|----.    .-----+----.   .----+------.
  |    | '------' '------' |    |    | Switch 1 |   | Switch 2  |
  |    '---,---------------'    |    |          +---+           |
  |       /                     |    '----+-----'   '----+------'
  |  .---'---.    .------.      |         |              |
  |  |  br0  |----| VM 1 |      |      ~~~~~~~~~~~~~~~~~~~~~
  |  '-------'    '------'      |     (                     )
  |      |        .------.      |     ( Rest of Network     )
  |      '--------| VM # |      |     (_____________________)
  |               '------'      |
  |  Host 1                     |
  '-----------------------------'

Where 'VM1' and 'VM#' are hosts connected to a Linux bridge, br0, with
bond0 and its associated links, eth0 & eth1, provide ingress/egress. One
can assume bond0, br1, and hosts VM1 to VM# are all contained in a
single box, as depicted. Interfaces eth0 and eth1 provide redundant
connections to the data center with the requirement to use all bandwidth
when the system is functioning normally. Switch 1 and Switch 2 are
physical switches that do not implement any advanced L2 management
features such as MLAG, Cisco's VPC, or LACP.

Combining this feature with vlan+srcmac hash policy allows a user to
create an access network without the need to use expensive switches that
support features like Cisco's VCP.

[1] https://docs.openvswitch.org/en/latest/topics/bonding/#slb-bonding

Co-developed-by: Long Xin <redacted>
Signed-off-by: Long Xin <redacted>
Signed-off-by: Jonathan Toppins <redacted>
---

Notes:
    v2:
     * dropped needless abstraction functions and put code in module init
     * renamed variable "rc" to "ret" to stay consistent with most of the
       code
     * fixed parameter setting management, when arp-monitor is turned on
       this feature will be turned off similar to how miimon and arp-monitor
       interact
     * renamed bond_xor_recv to bond_mac_filter_recv for a little more
       clarity
     * it appears the implied default return code for any bonding recv probe
       must be `RX_HANDLER_ANOTHER`. Changed the default return code of
       bond_mac_filter_recv to use this return value to not break skb
       processing when the skb dev is switched to the bond dev:
         `skb->dev = bond->dev`
    
    v3: Nik's comments
     * clarified documentation
     * fixed inline and basic reverse Christmas tree formatting
     * zero'ed entry in mac_create
     * removed read_lock taking in bond_mac_filter_recv
     * made has_expired() atomic and removed critical sections
       surrounding calls to has_expired(), this also removed the
       use-after-free that would have occurred:
           spin_lock_irqsave(&entry->lock, flags);
               if (has_expired(bond, entry))
                   mac_delete(bond, entry);
           spin_unlock_irqrestore(&entry->lock, flags); <---
     * moved init/destroy of mac_filter_tbl to bond_open/bond_close
       this removed the complex option dependencies, the only behavioural
       change the user will see is if the bond is up and mac_filter is
       enabled if they try and set arp_interval they will receive -EBUSY
     * in bond_changelink moved processing of mac_filter option just below
       mode processing

 Documentation/networking/bonding.rst  |  20 +++
 drivers/net/bonding/Makefile          |   2 +-
 drivers/net/bonding/bond_mac_filter.c | 201 ++++++++++++++++++++++++++
 drivers/net/bonding/bond_mac_filter.h |  37 +++++
 drivers/net/bonding/bond_main.c       |  30 ++++
 drivers/net/bonding/bond_netlink.c    |  13 ++
 drivers/net/bonding/bond_options.c    |  81 +++++++++--
 drivers/net/bonding/bonding_priv.h    |   1 +
 include/net/bond_options.h            |   1 +
 include/net/bonding.h                 |   3 +
 include/uapi/linux/if_link.h          |   1 +
 11 files changed, 373 insertions(+), 17 deletions(-)
 create mode 100644 drivers/net/bonding/bond_mac_filter.c
 create mode 100644 drivers/net/bonding/bond_mac_filter.h

[snip]

The same problem solved using a few nftables rules (in case you don't want to load eBPF):
$ nft 'add table netdev nt'
$ nft 'add chain netdev nt bond0EgressFilter { type filter hook egress device bond0 priority 0; }'
$ nft 'add chain netdev nt bond0IngressFilter { type filter hook ingress device bond0 priority 0; }'
$ nft 'add set netdev nt macset { type ether_addr; flags timeout; }'
$ nft 'add rule netdev nt bond0EgressFilter set update ether saddr timeout 5s @macset'
$ nft 'add rule netdev nt bond0IngressFilter ether saddr @macset counter drop'

Cheers,
 Nik