batman-adv/patches/0053-batman-adv-mcast-fix-duplicate-mcast-packets-in-BLA-.patch

   1 From: Linus Lüssing <linus.luessing@c0d3.blue>
   2 Date: Tue, 15 Sep 2020 09:54:09 +0200
   3 Subject: batman-adv: mcast: fix duplicate mcast packets in BLA backbone from mesh
   4
   5 Scenario:
   6 * Multicast frame send from mesh to a BLA backbone (multiple nodes
   7   with their bat0 bridged together, with BLA enabled)
   8
   9 Issue:
  10 * BLA backbone nodes receive the frame multiple times on bat0,
  11   once from mesh->bat0 and once from each backbone_gw from LAN
  12
  13 For unicast, a node will send only to the best backbone gateway
  14 according to the TQ. However for multicast we currently cannot determine
  15 if multiple destination nodes share the same backbone if they don't share
  16 the same backbone with us. So we need to keep sending the unicasts to
  17 all backbone gateways and let the backbone gateways decide which one
  18 will forward the frame. We can use the CLAIM mechanism to make this
  19 decision.
  20
  21 One catch: The batman-adv gateway feature for DHCP packets potentially
  22 sends multicast packets in the same batman-adv unicast header as the
  23 multicast optimizations code. And we are not allowed to drop those even
  24 if we did not claim the source address of the sender, as for such
  25 packets there is only this one multicast-in-unicast packet.
  26
  27 How can we distinguish the two cases?
  28
  29 The gateway feature uses a batman-adv unicast 4 address header. While
  30 the multicast-to-unicasts feature uses a simple, 3 address batman-adv
  31 unicast header. So let's use this to distinguish.
  32
  33 Fixes: e32470167379 ("batman-adv: check incoming packet type for bla")
  34 Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
  35 Acked-by: Simon Wunderlich <sw@simonwunderlich.de>
  36 Signed-off-by: Sven Eckelmann <sven@narfation.org>
  37
  38 Origin: upstream, https://git.open-mesh.org/batman-adv.git/commit/d7665cf8a824c41c61c6e2110ab63d37eb7a8ef7
  39
  40 diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
  41 index 26f590ba31d49a85143f67f1c002a25dc007b594..4dc67a0d081c06507aba87f7bec03488817791b2 100644
  42 --- a/net/batman-adv/bridge_loop_avoidance.c
  43 +++ b/net/batman-adv/bridge_loop_avoidance.c
  44 @@ -1827,7 +1827,7 @@ batadv_bla_loopdetect_check(struct batadv_priv *bat_priv, struct sk_buff *skb,
  45   * @bat_priv: the bat priv with all the soft interface information
  46   * @skb: the frame to be checked
  47   * @vid: the VLAN ID of the frame
  48 - * @is_bcast: the packet came in a broadcast packet type.
  49 + * @packet_type: the batman packet type this frame came in
  50   *
  51   * batadv_bla_rx avoidance checks if:
  52   *  * we have to race for a claim
  53 @@ -1839,7 +1839,7 @@ batadv_bla_loopdetect_check(struct batadv_priv *bat_priv, struct sk_buff *skb,
  54   * further process the skb.
  55   */
  56  bool batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb,
  57 -                  unsigned short vid, bool is_bcast)
  58 +                  unsigned short vid, int packet_type)
  59  {
  60         struct batadv_bla_backbone_gw *backbone_gw;
  61         struct ethhdr *ethhdr;
  62 @@ -1861,9 +1861,24 @@ bool batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb,
  63                 goto handled;
  64
  65         if (unlikely(atomic_read(&bat_priv->bla.num_requests)))
  66 -               /* don't allow broadcasts while requests are in flight */
  67 -               if (is_multicast_ether_addr(ethhdr->h_dest) && is_bcast)
  68 -                       goto handled;
  69 +               /* don't allow multicast packets while requests are in flight */
  70 +               if (is_multicast_ether_addr(ethhdr->h_dest))
  71 +                       /* Both broadcast flooding or multicast-via-unicasts
  72 +                        * delivery might send to multiple backbone gateways
  73 +                        * sharing the same LAN and therefore need to coordinate
  74 +                        * which backbone gateway forwards into the LAN,
  75 +                        * by claiming the payload source address.
  76 +                        *
  77 +                        * Broadcast flooding and multicast-via-unicasts
  78 +                        * delivery use the following two batman packet types.
  79 +                        * Note: explicitly exclude BATADV_UNICAST_4ADDR,
  80 +                        * as the DHCP gateway feature will send explicitly
  81 +                        * to only one BLA gateway, so the claiming process
  82 +                        * should be avoided there.
  83 +                        */
  84 +                       if (packet_type == BATADV_BCAST ||
  85 +                           packet_type == BATADV_UNICAST)
  86 +                               goto handled;
  87
  88         ether_addr_copy(search_claim.addr, ethhdr->h_source);
  89         search_claim.vid = vid;
  90 @@ -1898,13 +1913,14 @@ bool batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb,
  91                 goto allow;
  92         }
  93
  94 -       /* if it is a broadcast ... */
  95 -       if (is_multicast_ether_addr(ethhdr->h_dest) && is_bcast) {
  96 +       /* if it is a multicast ... */
  97 +       if (is_multicast_ether_addr(ethhdr->h_dest) &&
  98 +           (packet_type == BATADV_BCAST || packet_type == BATADV_UNICAST)) {
  99                 /* ... drop it. the responsible gateway is in charge.
 100                  *
 101 -                * We need to check is_bcast because with the gateway
 102 +                * We need to check packet type because with the gateway
 103                  * feature, broadcasts (like DHCP requests) may be sent
 104 -                * using a unicast packet type.
 105 +                * using a unicast 4 address packet type. See comment above.
 106                  */
 107                 goto handled;
 108         } else {
 109 diff --git a/net/batman-adv/bridge_loop_avoidance.h b/net/batman-adv/bridge_loop_avoidance.h
 110 index 71f95a3e4d3f335890408685432f18e5d7411a76..af28fdb01467ce290c2a00d0741f01a6e4f347ee 100644
 111 --- a/net/batman-adv/bridge_loop_avoidance.h
 112 +++ b/net/batman-adv/bridge_loop_avoidance.h
 113 @@ -48,7 +48,7 @@ static inline bool batadv_bla_is_loopdetect_mac(const uint8_t *mac)
 114
 115  #ifdef CONFIG_BATMAN_ADV_BLA
 116  bool batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb,
 117 -                  unsigned short vid, bool is_bcast);
 118 +                  unsigned short vid, int packet_type);
 119  bool batadv_bla_tx(struct batadv_priv *bat_priv, struct sk_buff *skb,
 120                    unsigned short vid);
 121  bool batadv_bla_is_backbone_gw(struct sk_buff *skb,
 122 @@ -79,7 +79,7 @@ bool batadv_bla_check_claim(struct batadv_priv *bat_priv, u8 *addr,
 123
 124  static inline bool batadv_bla_rx(struct batadv_priv *bat_priv,
 125                                  struct sk_buff *skb, unsigned short vid,
 126 -                                bool is_bcast)
 127 +                                int packet_type)
 128  {
 129         return false;
 130  }
 131 diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
 132 index 267f6e6c802f1a7d3eb41a0f3aa2142ca3b21414..82582abd92485b68254789fb6e2108ae5e547dd6 100644
 133 --- a/net/batman-adv/soft-interface.c
 134 +++ b/net/batman-adv/soft-interface.c
 135 @@ -425,10 +425,10 @@ void batadv_interface_rx(struct net_device *soft_iface,
 136         struct vlan_ethhdr *vhdr;
 137         struct ethhdr *ethhdr;
 138         unsigned short vid;
 139 -       bool is_bcast;
 140 +       int packet_type;
 141
 142         batadv_bcast_packet = (struct batadv_bcast_packet *)skb->data;
 143 -       is_bcast = (batadv_bcast_packet->packet_type == BATADV_BCAST);
 144 +       packet_type = batadv_bcast_packet->packet_type;
 145
 146         skb_pull_rcsum(skb, hdr_size);
 147         skb_reset_mac_header(skb);
 148 @@ -471,7 +471,7 @@ void batadv_interface_rx(struct net_device *soft_iface,
 149         /* Let the bridge loop avoidance check the packet. If will
 150          * not handle it, we can safely push it up.
 151          */
 152 -       if (batadv_bla_rx(bat_priv, skb, vid, is_bcast))
 153 +       if (batadv_bla_rx(bat_priv, skb, vid, packet_type))
 154                 goto out;
 155
 156         if (orig_node)