[PATCH net-next 2/4] packet: add eBPF fanout mode

[Willem de Bruijn]

From: Willem de Bruijn <will...@google.com>

Add a fanout mode that accepts an eBPF program to select a socket.

Update the internal eBPF program by passing to socket option
SOL_PACKET/PACKET_FANOUT_DATA a file descriptor returned by bpf().

Signed-off-by: Willem de Bruijn <will...@google.com>
---
 include/uapi/linux/if_packet.h |  1 +
 net/packet/af_packet.c         | 25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/include/uapi/linux/if_packet.h b/include/uapi/linux/if_packet.h
index d41280a..daa0ddd 100644
--- a/include/uapi/linux/if_packet.h
+++ b/include/uapi/linux/if_packet.h
@@ -64,6 +64,7 @@ struct sockaddr_ll {
 #define PACKET_FANOUT_RND              4
 #define PACKET_FANOUT_QM               5
 #define PACKET_FANOUT_BPF              6
+#define PACKET_FANOUT_EBPF             7
 #define PACKET_FANOUT_FLAG_ROLLOVER    0x1000
 #define PACKET_FANOUT_FLAG_DEFRAG      0x8000
 
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 80d68c9..6352b7d 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1472,6 +1472,7 @@ static int packet_rcv_fanout(struct sk_buff *skb, struct 
net_device *dev,
                idx = fanout_demux_rollover(f, skb, 0, false, num);
                break;
        case PACKET_FANOUT_BPF:
+       case PACKET_FANOUT_EBPF:
                idx = fanout_demux_bpf(f, skb, num);
                break;
        }
@@ -1529,6 +1530,7 @@ static void fanout_init_data(struct packet_fanout *f)
                atomic_set(&f->rr_cur, 0);
                break;
        case PACKET_FANOUT_BPF:
+       case PACKET_FANOUT_EBPF:
                RCU_INIT_POINTER(f->bpf_prog, NULL);
                break;
        }
@@ -1569,12 +1571,33 @@ static int fanout_set_data_bpf(struct packet_fanout *f, 
char __user *data,
        return 0;
 }
 
+static int fanout_set_data_ebpf(struct packet_fanout *f, char __user *data,
+                               unsigned int len)
+{
+       struct bpf_prog *new;
+       u32 fd;
+
+       if (len != sizeof(fd))
+               return -EINVAL;
+       if (copy_from_user(&fd, data, len))
+               return -EFAULT;
+
+       new = bpf_prog_get(fd);
+       if (IS_ERR(new))
+               return PTR_ERR(new);
+
+       __fanout_set_data_bpf(f, new);
+       return 0;
+}
+
 static int fanout_set_data(struct packet_fanout *f, char __user *data,
                           unsigned int len)
 {
        switch (f->type) {
        case PACKET_FANOUT_BPF:
                return fanout_set_data_bpf(f, data, len);
+       case PACKET_FANOUT_EBPF:
+               return fanout_set_data_ebpf(f, data, len);
        default:
                return -EINVAL;
        };
@@ -1584,6 +1607,7 @@ static void fanout_release_data(struct packet_fanout *f)
 {
        switch (f->type) {
        case PACKET_FANOUT_BPF:
+       case PACKET_FANOUT_EBPF:
                __fanout_set_data_bpf(f, NULL);
        };
 }
@@ -1606,6 +1630,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 
type_flags)
        case PACKET_FANOUT_RND:
        case PACKET_FANOUT_QM:
        case PACKET_FANOUT_BPF:
+       case PACKET_FANOUT_EBPF:
                break;
        default:
                return -EINVAL;
-- 
2.5.0.276.gf5e568e

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