packet: add extended BPF fanout mode

Add fanout mode PACKET_FANOUT_EBPF that accepts an en extended BPF
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 <willemb@google.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 32 insertions, 0 deletions

diff --git a/include/uapi/linux/if_packet.h b/include/uapi/linux/if_packet.h
index a4bb16fa822e..9e7edfd8141e 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_CBPF              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 8869d07013e6..7b8e39a22387 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_CBPF:
+        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_CBPF:
+        case PACKET_FANOUT_EBPF:
                 RCU_INIT_POINTER(f->bpf_prog, NULL);
                 break;
         }
@@ -1571,12 +1573,39 @@ static int fanout_set_data_cbpf(struct packet_sock *po, char __user *data,
         return 0;
 }
 
+static int fanout_set_data_ebpf(struct packet_sock *po, char __user *data,
+                                unsigned int len)
+{
+        struct bpf_prog *new;
+        u32 fd;
+
+        if (sock_flag(&po->sk, SOCK_FILTER_LOCKED))
+                return -EPERM;
+        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);
+        if (new->type != BPF_PROG_TYPE_SOCKET_FILTER) {
+                bpf_prog_put(new);
+                return -EINVAL;
+        }
+
+        __fanout_set_data_bpf(po->fanout, new);
+        return 0;
+}
+
 static int fanout_set_data(struct packet_sock *po, char __user *data,
                            unsigned int len)
 {
         switch (po->fanout->type) {
         case PACKET_FANOUT_CBPF:
                 return fanout_set_data_cbpf(po, data, len);
+        case PACKET_FANOUT_EBPF:
+                return fanout_set_data_ebpf(po, data, len);
         default:
                 return -EINVAL;
         };
@@ -1586,6 +1615,7 @@ static void fanout_release_data(struct packet_fanout *f)
 {
         switch (f->type) {
         case PACKET_FANOUT_CBPF:
+        case PACKET_FANOUT_EBPF:
                 __fanout_set_data_bpf(f, NULL);
         };
 }
@@ -1608,6 +1638,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
         case PACKET_FANOUT_RND:
         case PACKET_FANOUT_QM:
         case PACKET_FANOUT_CBPF:
+        case PACKET_FANOUT_EBPF:
                 break;
         default:
                 return -EINVAL;