Commit bcd6f4a8 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by Alexei Starovoitov
Browse files

bpf: Allow to retrieve sol_socket opts from sock_addr progs 



The _bpf_setsockopt() is able to set some of the SOL_SOCKET level options,
however, _bpf_getsockopt() has little support to actually retrieve them.
This small patch adds few misc options such as SO_MARK, SO_PRIORITY and
SO_BINDTOIFINDEX. For the latter getter and setter are added. The mark and
priority in particular allow to retrieve the options from BPF cgroup hooks
to then implement custom behavior / settings on the syscall hooks compared
to other sockets that stick to the defaults, for example.

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/cba44439b801e5ddc1170e5be787f4dc93a2d7f9.1610406333.git.daniel@iogearbox.net
parent 28a8add6

net/core/filter.c

+23 −2
Original line number Diff line number Diff line
@@ -4770,6 +4770,10 @@ static int _bpf_setsockopt(struct sock *sk, int level, int optname, 
				ifindex = dev->ifindex;

				dev_put(dev);

			}

			fallthrough;

		case SO_BINDTOIFINDEX:

			if (optname == SO_BINDTOIFINDEX)

				ifindex = val;

			ret = sock_bindtoindex(sk, ifindex, false);

			break;

		case SO_KEEPALIVE:
@@ -4932,8 +4936,25 @@ static int _bpf_getsockopt(struct sock *sk, int level, int optname, 


	sock_owned_by_me(sk);



	if (level == SOL_SOCKET) {

		if (optlen != sizeof(int))

			goto err_clear;



		switch (optname) {

		case SO_MARK:

			*((int *)optval) = sk->sk_mark;

			break;

		case SO_PRIORITY:

			*((int *)optval) = sk->sk_priority;

			break;

		case SO_BINDTOIFINDEX:

			*((int *)optval) = sk->sk_bound_dev_if;

			break;

		default:

			goto err_clear;

		}

#ifdef CONFIG_INET

	if (level == SOL_TCP && sk->sk_prot->getsockopt == tcp_getsockopt) {

	} else if (level == SOL_TCP && sk->sk_prot->getsockopt == tcp_getsockopt) {

		struct inet_connection_sock *icsk;

		struct tcp_sock *tp;
@@ -4986,12 +5007,12 @@ static int _bpf_getsockopt(struct sock *sk, int level, int optname, 
		default:

			goto err_clear;

		}

#endif

#endif

	} else {

		goto err_clear;

	}

	return 0;

#endif

err_clear:

	memset(optval, 0, optlen);

	return -EINVAL;