net: sock: allow eBPF programs to be attached to sockets

introduce new setsockopt() command:

setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd, sizeof(prog_fd))

where prog_fd was received from syscall bpf(BPF_PROG_LOAD, attr, ...)
and attr->prog_type == BPF_PROG_TYPE_SOCKET_FILTER

setsockopt() calls bpf_prog_get() which increments refcnt of the program,
so it doesn't get unloaded while socket is using the program.

The same eBPF program can be attached to multiple sockets.

User task exit automatically closes socket which calls sk_filter_uncharge()
which decrements refcnt of eBPF program

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 0 deletions

diff --git a/net/core/sock.c b/net/core/sock.c
index 0725cf0cb685..9a56b2000c3f 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -888,6 +888,19 @@ set_rcvbuf:
                 }
                 break;
 
+        case SO_ATTACH_BPF:
+                ret = -EINVAL;
+                if (optlen == sizeof(u32)) {
+                        u32 ufd;
+
+                        ret = -EFAULT;
+                        if (copy_from_user(&ufd, optval, sizeof(ufd)))
+                                break;
+
+                        ret = sk_attach_bpf(ufd, sk);
+                }
+                break;
+
         case SO_DETACH_FILTER:
                 ret = sk_detach_filter(sk);
                 break;