net: implement XDP_REDIRECT for xdp generic

Add support for redirect to xdp generic creating a fall back for
devices that do not yet have support and allowing test infrastructure
using veth pairs to be built.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Tested-by: Andy Gospodarek <andy@greyhouse.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 64cae7a..10df7da 100644 (file)
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -712,6 +712,7 @@ bool bpf_helper_changes_pkt_data(void *func);
 struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
                                       const struct bpf_insn *patch, u32 len);
 
+int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb);
 int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp);
 
 void bpf_warn_invalid_xdp_action(u32 act);

diff --git a/net/core/dev.c b/net/core/dev.c
index a1ed7b4..9f3f408 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3902,6 +3902,7 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb,
                __skb_push(skb, -off);
 
        switch (act) {
+       case XDP_REDIRECT:
        case XDP_TX:
                __skb_push(skb, mac_len);
                /* fall through */
@@ -3956,14 +3957,27 @@ static int do_xdp_generic(struct sk_buff *skb)
 
        if (xdp_prog) {
                u32 act = netif_receive_generic_xdp(skb, xdp_prog);
+               int err;
 
                if (act != XDP_PASS) {
-                       if (act == XDP_TX)
+                       switch (act) {
+                       case XDP_REDIRECT:
+                               err = xdp_do_generic_redirect(skb->dev, skb);
+                               if (err)
+                                       goto out_redir;
+                       /* fallthru to submit skb */
+                       case XDP_TX:
                                generic_xdp_tx(skb, xdp_prog);
+                               break;
+                       }
                        return XDP_DROP;
                }
        }
        return XDP_PASS;
+out_redir:
+       trace_xdp_exception(skb->dev, xdp_prog, XDP_REDIRECT);
+       kfree_skb(skb);
+       return XDP_DROP;
 }
 
 static int netif_rx_internal(struct sk_buff *skb)
@@ -3977,8 +3991,12 @@ static int netif_rx_internal(struct sk_buff *skb)
        if (static_key_false(&generic_xdp_needed)) {
                int ret = do_xdp_generic(skb);
 
+               /* Consider XDP consuming the packet a success from
+                * the netdev point of view we do not want to count
+                * this as an error.
+                */
                if (ret != XDP_PASS)
-                       return NET_RX_DROP;
+                       return NET_RX_SUCCESS;
        }
 
 #ifdef CONFIG_RPS

diff --git a/net/core/filter.c b/net/core/filter.c
index d606a66..eeb7134 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2437,6 +2437,32 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp)
 }
 EXPORT_SYMBOL_GPL(xdp_do_redirect);
 
+int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb)
+{
+       struct redirect_info *ri = this_cpu_ptr(&redirect_info);
+       unsigned int len;
+
+       dev = dev_get_by_index_rcu(dev_net(dev), ri->ifindex);
+       ri->ifindex = 0;
+       if (unlikely(!dev)) {
+               bpf_warn_invalid_xdp_redirect(ri->ifindex);
+               goto err;
+       }
+
+       if (unlikely(!(dev->flags & IFF_UP)))
+               goto err;
+
+       len = dev->mtu + dev->hard_header_len + VLAN_HLEN;
+       if (skb->len > len)
+               goto err;
+
+       skb->dev = dev;
+       return 0;
+err:
+       return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(xdp_do_generic_redirect);
+
 BPF_CALL_2(bpf_xdp_redirect, u32, ifindex, u64, flags)
 {
        struct redirect_info *ri = this_cpu_ptr(&redirect_info);