On Sat, Nov 23, 2019 at 12:07:47PM +0100, Jakub Sitnicki wrote:
[ ... ]
> @@ -370,6 +378,11 @@ static inline void sk_psock_restore_proto(struct sock *sk,
> sk->sk_prot = psock->sk_proto;
> psock->sk_proto = NULL;
> }
> +
> + if (psock->icsk_af_ops) {
> + icsk->icsk_af_ops = psock->icsk_af_ops;
> + psock->icsk_af_ops = NULL;
> + }
> }
[ ... ]
> +static struct sock *tcp_bpf_syn_recv_sock(const struct sock *sk,
> + struct sk_buff *skb,
> + struct request_sock *req,
> + struct dst_entry *dst,
> + struct request_sock *req_unhash,
> + bool *own_req)
> +{
> + const struct inet_connection_sock_af_ops *ops;
> + void (*write_space)(struct sock *sk);
> + struct sk_psock *psock;
> + struct proto *proto;
> + struct sock *child;
> +
> + rcu_read_lock();
> + psock = sk_psock(sk);
> + if (likely(psock)) {
> + proto = psock->sk_proto;
> + write_space = psock->saved_write_space;
> + ops = psock->icsk_af_ops;
It is not immediately clear to me what ensure
ops is not NULL here.
It is likely I missed something. A short comment would
be very useful here.
> + } else {
> + ops = inet_csk(sk)->icsk_af_ops;
> + }
> + rcu_read_unlock();
> +
> + child = ops->syn_recv_sock(sk, skb, req, dst, req_unhash, own_req);
> +
> + /* Child must not inherit psock or its ops. */
> + if (child && psock) {
> + rcu_assign_sk_user_data(child, NULL);
> + child->sk_prot = proto;
> + child->sk_write_space = write_space;
> +
> + /* v4-mapped sockets don't inherit parent ops. Don't restore. */
> + if (inet_csk(child)->icsk_af_ops == inet_csk(sk)->icsk_af_ops)
> + inet_csk(child)->icsk_af_ops = ops;
> + }
> + return child;
> +}
> +
> enum {
> TCP_BPF_IPV4,
> TCP_BPF_IPV6,
> @@ -597,6 +642,7 @@ enum {
> static struct proto *tcpv6_prot_saved __read_mostly;
> static DEFINE_SPINLOCK(tcpv6_prot_lock);
> static struct proto tcp_bpf_prots[TCP_BPF_NUM_PROTS][TCP_BPF_NUM_CFGS];
> +static struct inet_connection_sock_af_ops tcp_bpf_af_ops[TCP_BPF_NUM_PROTS];
>
> static void tcp_bpf_rebuild_protos(struct proto prot[TCP_BPF_NUM_CFGS],
> struct proto *base)
> @@ -612,13 +658,23 @@ static void tcp_bpf_rebuild_protos(struct proto prot[TCP_BPF_NUM_CFGS],
> prot[TCP_BPF_TX].sendpage = tcp_bpf_sendpage;
> }
>
> -static void tcp_bpf_check_v6_needs_rebuild(struct sock *sk, struct proto *ops)
> +static void tcp_bpf_rebuild_af_ops(struct inet_connection_sock_af_ops *ops,
> + const struct inet_connection_sock_af_ops *base)
> +{
> + *ops = *base;
> + ops->syn_recv_sock = tcp_bpf_syn_recv_sock;
> +}
> +
> +static void tcp_bpf_check_v6_needs_rebuild(struct sock *sk, struct proto *ops,
> + const struct inet_connection_sock_af_ops *af_ops)
> {
> if (sk->sk_family == AF_INET6 &&
> unlikely(ops != smp_load_acquire(&tcpv6_prot_saved))) {
> spin_lock_bh(&tcpv6_prot_lock);
> if (likely(ops != tcpv6_prot_saved)) {
> tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV6], ops);
> + tcp_bpf_rebuild_af_ops(&tcp_bpf_af_ops[TCP_BPF_IPV6],
> + af_ops);
> smp_store_release(&tcpv6_prot_saved, ops);
> }
> spin_unlock_bh(&tcpv6_prot_lock);
> @@ -628,6 +684,8 @@ static void tcp_bpf_check_v6_needs_rebuild(struct sock *sk, struct proto *ops)
> static int __init tcp_bpf_v4_build_proto(void)
> {
> tcp_bpf_rebuild_protos(tcp_bpf_prots[TCP_BPF_IPV4], &tcp_prot);
> + tcp_bpf_rebuild_af_ops(&tcp_bpf_af_ops[TCP_BPF_IPV4], &ipv4_specific);
> +
> return 0;
> }
> core_initcall(tcp_bpf_v4_build_proto);
> @@ -637,7 +695,8 @@ static void tcp_bpf_update_sk_prot(struct sock *sk, struct sk_psock *psock)
> int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
> int config = psock->progs.msg_parser ? TCP_BPF_TX : TCP_BPF_BASE;
>
> - sk_psock_update_proto(sk, psock, &tcp_bpf_prots[family][config]);
> + sk_psock_update_proto(sk, psock, &tcp_bpf_prots[family][config],
> + &tcp_bpf_af_ops[family]);
> }
>
> static void tcp_bpf_reinit_sk_prot(struct sock *sk, struct sk_psock *psock)
> @@ -677,6 +736,7 @@ void tcp_bpf_reinit(struct sock *sk)
>
> int tcp_bpf_init(struct sock *sk)
> {
> + struct inet_connection_sock *icsk = inet_csk(sk);
> struct proto *ops = READ_ONCE(sk->sk_prot);
> struct sk_psock *psock;
>
> @@ -689,7 +749,7 @@ int tcp_bpf_init(struct sock *sk)
> rcu_read_unlock();
> return -EINVAL;
> }
> - tcp_bpf_check_v6_needs_rebuild(sk, ops);
> + tcp_bpf_check_v6_needs_rebuild(sk, ops, icsk->icsk_af_ops);
> tcp_bpf_update_sk_prot(sk, psock);
> rcu_read_unlock();
> return 0;
> --
> 2.20.1
>
