From d44874910a26f3a8f81edf873a2473363f07f660 Mon Sep 17 00:00:00 2001 From: Lawrence Brakmo Date: Thu, 25 Jan 2018 16:14:15 -0800 Subject: bpf: Add BPF_SOCK_OPS_STATE_CB Adds support for calling sock_ops BPF program when there is a TCP state change. Two arguments are used; one for the old state and another for the new state. There is a new enum in include/uapi/linux/bpf.h that exports the TCP states that prepends BPF_ to the current TCP state names. If it is ever necessary to change the internal TCP state values (other than adding more to the end), then it will become necessary to convert from the internal TCP state value to the BPF value before calling the BPF sock_ops function. There are a set of compile checks added in tcp.c to detect if the internal and BPF values differ so we can make the necessary fixes. New op: BPF_SOCK_OPS_STATE_CB. Signed-off-by: Lawrence Brakmo Signed-off-by: Alexei Starovoitov --- net/ipv4/tcp.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'net/ipv4/tcp.c') diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 88b62441e7e9..f013ddc191e0 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2042,6 +2042,30 @@ void tcp_set_state(struct sock *sk, int state) { int oldstate = sk->sk_state; + /* We defined a new enum for TCP states that are exported in BPF + * so as not force the internal TCP states to be frozen. The + * following checks will detect if an internal state value ever + * differs from the BPF value. If this ever happens, then we will + * need to remap the internal value to the BPF value before calling + * tcp_call_bpf_2arg. + */ + BUILD_BUG_ON((int)BPF_TCP_ESTABLISHED != (int)TCP_ESTABLISHED); + BUILD_BUG_ON((int)BPF_TCP_SYN_SENT != (int)TCP_SYN_SENT); + BUILD_BUG_ON((int)BPF_TCP_SYN_RECV != (int)TCP_SYN_RECV); + BUILD_BUG_ON((int)BPF_TCP_FIN_WAIT1 != (int)TCP_FIN_WAIT1); + BUILD_BUG_ON((int)BPF_TCP_FIN_WAIT2 != (int)TCP_FIN_WAIT2); + BUILD_BUG_ON((int)BPF_TCP_TIME_WAIT != (int)TCP_TIME_WAIT); + BUILD_BUG_ON((int)BPF_TCP_CLOSE != (int)TCP_CLOSE); + BUILD_BUG_ON((int)BPF_TCP_CLOSE_WAIT != (int)TCP_CLOSE_WAIT); + BUILD_BUG_ON((int)BPF_TCP_LAST_ACK != (int)TCP_LAST_ACK); + BUILD_BUG_ON((int)BPF_TCP_LISTEN != (int)TCP_LISTEN); + BUILD_BUG_ON((int)BPF_TCP_CLOSING != (int)TCP_CLOSING); + BUILD_BUG_ON((int)BPF_TCP_NEW_SYN_RECV != (int)TCP_NEW_SYN_RECV); + BUILD_BUG_ON((int)BPF_TCP_MAX_STATES != (int)TCP_MAX_STATES); + + if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_STATE_CB_FLAG)) + tcp_call_bpf_2arg(sk, BPF_SOCK_OPS_STATE_CB, oldstate, state); + switch (state) { case TCP_ESTABLISHED: if (oldstate != TCP_ESTABLISHED) -- cgit v1.2.3