bpf: Disallow bpf_{g,s}etsockopt() in cgroup UNIX getname hooks

In the Linux kernel, the following vulnerability has been resolved: bpf: Disallow bpf_{g,s}etsockopt() in cgroup UNIX getname hooks _bpf_setsockopt() and _bpf_getsockopt() call sock_owned_by_me() for full sockets, so these helpers expect the socket lock to be held. BPF_CGROUP_UNIX_GETPEERNAME and BPF_CGROUP_UNIX_GETSOCKNAME run BPF programs without acquiring the socket lock. A program attached to either hook can therefore trigger the sock_owned_by_me() warning by calling bpf_setsockopt() or bpf_getsockopt(). Disallow bpf_setsockopt() and bpf_getsockopt() for CGROUP_UNIX_GETPEERNAME and CGROUP_UNIX_GETSOCKNAME.