From bcd6f4a8bedabac6949d05e418e73a0a1b309e84 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Tue, 12 Jan 2021 00:09:39 +0100 Subject: [PATCH] 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: Daniel Borkmann Signed-off-by: Alexei Starovoitov Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/cba44439b801e5ddc1170e5be787f4dc93a2d7f9.1610406333.git.daniel@iogearbox.net --- net/core/filter.c | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index 255aeee72402..9ab94e90d660 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -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; @@ -4987,11 +5008,11 @@ static int _bpf_getsockopt(struct sock *sk, int level, int optname, goto err_clear; } #endif +#endif } else { goto err_clear; } return 0; -#endif err_clear: memset(optval, 0, optlen); return -EINVAL; -- 2.11.0