drop support for pre-4.14 kernels

S had a minimum kernel requirement of 4.9,
T bumps this up to 4.14, which adds net cgroup bpf support.

It's important to ship T with this otherwise we'll be forced
into trying to somehow support 4.9 kernels with T mainline
module updates for years and years, when we no longer have
any tests of the old code paths...

Test: TreeHugger
Bug: 232017472
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I6e873f0815f176f5618278087132156c9974d6ea
diff --git a/bpf_progs/netd.c b/bpf_progs/netd.c
index fe9a871..c980047 100644
--- a/bpf_progs/netd.c
+++ b/bpf_progs/netd.c
@@ -373,8 +373,7 @@
     return BPF_NOMATCH;
 }
 
-DEFINE_BPF_PROG_KVER("cgroupsock/inet/create", AID_ROOT, AID_ROOT, inet_socket_create,
-                     KVER(4, 14, 0))
+DEFINE_BPF_PROG("cgroupsock/inet/create", AID_ROOT, AID_ROOT, inet_socket_create)
 (struct bpf_sock* sk) {
     uint64_t gid_uid = bpf_get_current_uid_gid();
     /*
diff --git a/netd/BpfHandler.cpp b/netd/BpfHandler.cpp
index f3dfb57..08e66d9 100644
--- a/netd/BpfHandler.cpp
+++ b/netd/BpfHandler.cpp
@@ -73,16 +73,7 @@
     }
     RETURN_IF_NOT_OK(attachProgramToCgroup(BPF_EGRESS_PROG_PATH, cg_fd, BPF_CGROUP_INET_EGRESS));
     RETURN_IF_NOT_OK(attachProgramToCgroup(BPF_INGRESS_PROG_PATH, cg_fd, BPF_CGROUP_INET_INGRESS));
-
-    // For the devices that support cgroup socket filter, the socket filter
-    // should be loaded successfully by bpfloader. So we attach the filter to
-    // cgroup if the program is pinned properly.
-    // TODO: delete the if statement once all devices should support cgroup
-    // socket filter (ie. the minimum kernel version required is 4.14).
-    if (!access(CGROUP_SOCKET_PROG_PATH, F_OK)) {
-        RETURN_IF_NOT_OK(
-                attachProgramToCgroup(CGROUP_SOCKET_PROG_PATH, cg_fd, BPF_CGROUP_INET_SOCK_CREATE));
-    }
+    RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_SOCKET_PROG_PATH, cg_fd, BPF_CGROUP_INET_SOCK_CREATE));
     return netdutils::status::ok;
 }