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bpf: Allow to retrieve sol_socket opts from sock_addr progs

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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: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/cba44439b801e5ddc1170e5be787f4dc93a2d7f9.1610406333.git.daniel@iogearbox.net
This commit is contained in:
Daniel Borkmann 2021-01-12 00:09:39 +01:00 committed by Alexei Starovoitov
parent 28a8add641
commit bcd6f4a8be
1 changed files with 23 additions and 2 deletions
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25
net/core/filter.c
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@ -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;