On Fri, Jul 31, 2020 at 01:44:19PM +0900, Yoshiki Komachi wrote:
> This patch adds a new bpf helper to access FDB in the kernel tables
> from XDP programs. The helper enables us to find the destination port
> of master bridge in XDP layer with high speed. If an entry in the
> tables is successfully found, egress device index will be returned.
>
> In cases of failure, packets will be dropped or forwarded to upper
> networking stack in the kernel by XDP programs. Multicast and broadcast
> packets are currently not supported. Thus, these will need to be
> passed to upper layer on the basis of XDP_PASS action.
>
> The API uses destination MAC and VLAN ID as keys, so XDP programs
> need to extract these from forwarded packets.
>
> Signed-off-by: Yoshiki Komachi <komachi.yoshiki@xxxxxxxxx>
> ---
> include/uapi/linux/bpf.h | 28 +++++++++++++++++++++
> net/core/filter.c | 45 ++++++++++++++++++++++++++++++++++
> scripts/bpf_helpers_doc.py | 1 +
> tools/include/uapi/linux/bpf.h | 28 +++++++++++++++++++++
> 4 files changed, 102 insertions(+)
>
[...]
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 654c346b7d91..68800d1b8cd5 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -45,6 +45,7 @@
> #include <linux/filter.h>
> #include <linux/ratelimit.h>
> #include <linux/seccomp.h>
> +#include <linux/if_bridge.h>
> #include <linux/if_vlan.h>
> #include <linux/bpf.h>
> #include <linux/btf.h>
> @@ -5084,6 +5085,46 @@ static const struct bpf_func_proto bpf_skb_fib_lookup_proto = {
> .arg4_type = ARG_ANYTHING,
> };
>
> +#if IS_ENABLED(CONFIG_BRIDGE)
> +BPF_CALL_4(bpf_xdp_fdb_lookup, struct xdp_buff *, ctx,
> + struct bpf_fdb_lookup *, params, int, plen, u32, flags)
> +{
> + struct net_device *src, *dst;
> + struct net *net;
> +
> + if (plen < sizeof(*params))
> + return -EINVAL;
> +
> + net = dev_net(ctx->rxq->dev);
> +
> + if (is_multicast_ether_addr(params->addr) ||
> + is_broadcast_ether_addr(params->addr))
> + return BPF_FDB_LKUP_RET_NOENT;
small nit: you could move that validation before dev_net() call.
> +
> + src = dev_get_by_index_rcu(net, params->ifindex);
> + if (unlikely(!src))
> + return -ENODEV;
> +
> + dst = br_fdb_find_port_xdp(src, params->addr, params->vlan_id);
> + if (dst) {
> + params->ifindex = dst->ifindex;
> + return BPF_FDB_LKUP_RET_SUCCESS;
> + }
> +
> + return BPF_FDB_LKUP_RET_NOENT;
> +}
