releases/4.20.17/bonding-fix-packet_origdev-regression.patch

   1 From foo@baz Thu Mar 14 23:20:15 PDT 2019
   2 From: Michal Soltys <soltys@ziu.info>
   3 Date: Mon, 18 Feb 2019 17:55:28 +0100
   4 Subject: bonding: fix PACKET_ORIGDEV regression
   5
   6 From: Michal Soltys <soltys@ziu.info>
   7
   8 [ Upstream commit 3c963a3306eada999be5ebf4f293dfa3d3945487 ]
   9
  10 This patch fixes a subtle PACKET_ORIGDEV regression which was a side
  11 effect of fixes introduced by:
  12
  13 6a9e461f6fe4 bonding: pass link-local packets to bonding master also.
  14
  15 ... to:
  16
  17 b89f04c61efe bonding: deliver link-local packets with skb->dev set to link that packets arrived on
  18
  19 While 6a9e461f6fe4 restored pre-b89f04c61efe presence of link-local
  20 packets on bonding masters (which is required e.g. by linux bridges
  21 participating in spanning tree or needed for lab-like setups created
  22 with group_fwd_mask) it also caused the originating device
  23 information to be lost due to cloning.
  24
  25 Maciej Żenczykowski proposed another solution that doesn't require
  26 packet cloning and retains original device information - instead of
  27 returning RX_HANDLER_PASS for all link-local packets it's now limited
  28 only to packets from inactive slaves.
  29
  30 At the same time, packets passed to bonding masters retain correct
  31 information about the originating device and PACKET_ORIGDEV can be used
  32 to determine it.
  33
  34 This elegantly solves all issues so far:
  35
  36 - link-local packets that were removed from bonding masters
  37 - LLDP daemons being forced to explicitly bind to slave interfaces
  38 - PACKET_ORIGDEV having no effect on bond interfaces
  39
  40 Fixes: 6a9e461f6fe4 (bonding: pass link-local packets to bonding master also.)
  41 Reported-by: Vincent Bernat <vincent@bernat.ch>
  42 Signed-off-by: Michal Soltys <soltys@ziu.info>
  43 Signed-off-by: Maciej Żenczykowski <maze@google.com>
  44 Signed-off-by: David S. Miller <davem@davemloft.net>
  45 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  46 ---
  47  drivers/net/bonding/bond_main.c |   35 ++++++++++++++---------------------
  48  1 file changed, 14 insertions(+), 21 deletions(-)
  49
  50 --- a/drivers/net/bonding/bond_main.c
  51 +++ b/drivers/net/bonding/bond_main.c
  52 @@ -1172,29 +1172,22 @@ static rx_handler_result_t bond_handle_f
  53                 }
  54         }
  55
  56 -       /* Link-local multicast packets should be passed to the
  57 -        * stack on the link they arrive as well as pass them to the
  58 -        * bond-master device. These packets are mostly usable when
  59 -        * stack receives it with the link on which they arrive
  60 -        * (e.g. LLDP) they also must be available on master. Some of
  61 -        * the use cases include (but are not limited to): LLDP agents
  62 -        * that must be able to operate both on enslaved interfaces as
  63 -        * well as on bonds themselves; linux bridges that must be able
  64 -        * to process/pass BPDUs from attached bonds when any kind of
  65 -        * STP version is enabled on the network.
  66 +       /*
  67 +        * For packets determined by bond_should_deliver_exact_match() call to
  68 +        * be suppressed we want to make an exception for link-local packets.
  69 +        * This is necessary for e.g. LLDP daemons to be able to monitor
  70 +        * inactive slave links without being forced to bind to them
  71 +        * explicitly.
  72 +        *
  73 +        * At the same time, packets that are passed to the bonding master
  74 +        * (including link-local ones) can have their originating interface
  75 +        * determined via PACKET_ORIGDEV socket option.
  76          */
  77 -       if (is_link_local_ether_addr(eth_hdr(skb)->h_dest)) {
  78 -               struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
  79 -
  80 -               if (nskb) {
  81 -                       nskb->dev = bond->dev;
  82 -                       nskb->queue_mapping = 0;
  83 -                       netif_rx(nskb);
  84 -               }
  85 -               return RX_HANDLER_PASS;
  86 -       }
  87 -       if (bond_should_deliver_exact_match(skb, slave, bond))
  88 +       if (bond_should_deliver_exact_match(skb, slave, bond)) {
  89 +               if (is_link_local_ether_addr(eth_hdr(skb)->h_dest))
  90 +                       return RX_HANDLER_PASS;
  91                 return RX_HANDLER_EXACT;
  92 +       }
  93
  94         skb->dev = bond->dev;
  95