Added support for changing congestion control for SOCK_OPS bpf programs through the setsockopt bpf helper function. It also adds a new SOCK_OPS op, BPF_SOCK_OPS_NEEDS_ECN, that is needed for congestion controls, like dctcp, that need to enable ECN in the SYN packets.
Signed-off-by: Lawrence Brakmo <bra...@fb.com> --- include/net/tcp.h | 9 ++++++++- include/uapi/linux/bpf.h | 3 +++ net/core/filter.c | 11 +++++++++-- net/ipv4/tcp.c | 2 +- net/ipv4/tcp_cong.c | 32 ++++++++++++++++++++++---------- net/ipv4/tcp_input.c | 3 ++- net/ipv4/tcp_output.c | 8 +++++--- 7 files changed, 50 insertions(+), 18 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index ff806d7..58d67be 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1003,7 +1003,9 @@ void tcp_get_default_congestion_control(char *name); void tcp_get_available_congestion_control(char *buf, size_t len); void tcp_get_allowed_congestion_control(char *buf, size_t len); int tcp_set_allowed_congestion_control(char *allowed); -int tcp_set_congestion_control(struct sock *sk, const char *name); +int tcp_set_congestion_control(struct sock *sk, const char *name, bool load); +void tcp_reinit_congestion_control(struct sock *sk, + const struct tcp_congestion_ops *ca); u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); @@ -2072,4 +2074,9 @@ static inline u32 tcp_rwnd_init_bpf(struct sock *sk, bool is_req_sock) rwnd = 0; return rwnd; } + +static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk) +{ + return (tcp_call_bpf(sk, true, BPF_SOCK_OPS_NEEDS_ECN) == 1); +} #endif /* _TCP_H */ diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 4856d16..c222059 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -776,6 +776,9 @@ enum { * passive connection is * established */ + BPF_SOCK_OPS_NEEDS_ECN, /* If connection's congestion control + * needs ECN + */ }; #endif /* _UAPI__LINUX_BPF_H__ */ diff --git a/net/core/filter.c b/net/core/filter.c index b114ae1..bbf8f78 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2716,8 +2716,15 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock, } } else if (level == SOL_TCP && sk->sk_prot->setsockopt == tcp_setsockopt) { - /* Place holder */ - ret = -EINVAL; + if (optname == TCP_CONGESTION) { + ret = tcp_set_congestion_control(sk, optval, false); + if (!ret && bpf_sock->op > BPF_SOCK_OPS_NEEDS_ECN) + /* replacing an existing ca */ + tcp_reinit_congestion_control(sk, + inet_csk(sk)->icsk_ca_ops); + } else { + ret = -EINVAL; + } } else { ret = -EINVAL; } diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 058f509..9476fd6 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2479,7 +2479,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level, name[val] = 0; lock_sock(sk); - err = tcp_set_congestion_control(sk, name); + err = tcp_set_congestion_control(sk, name, true); release_sock(sk); return err; } diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c index 324c9bc..fde983f 100644 --- a/net/ipv4/tcp_cong.c +++ b/net/ipv4/tcp_cong.c @@ -189,8 +189,8 @@ void tcp_init_congestion_control(struct sock *sk) INET_ECN_dontxmit(sk); } -static void tcp_reinit_congestion_control(struct sock *sk, - const struct tcp_congestion_ops *ca) +void tcp_reinit_congestion_control(struct sock *sk, + const struct tcp_congestion_ops *ca) { struct inet_connection_sock *icsk = inet_csk(sk); @@ -333,8 +333,12 @@ int tcp_set_allowed_congestion_control(char *val) return ret; } -/* Change congestion control for socket */ -int tcp_set_congestion_control(struct sock *sk, const char *name) +/* Change congestion control for socket. If load is false, then it is the + * responsibility of the caller to call tcp_init_congestion_control or + * tcp_reinit_congestion_control (if the current congestion control was + * already initialized. + */ +int tcp_set_congestion_control(struct sock *sk, const char *name, bool load) { struct inet_connection_sock *icsk = inet_csk(sk); const struct tcp_congestion_ops *ca; @@ -344,21 +348,29 @@ int tcp_set_congestion_control(struct sock *sk, const char *name) return -EPERM; rcu_read_lock(); - ca = __tcp_ca_find_autoload(name); + if (!load) + ca = tcp_ca_find(name); + else + ca = __tcp_ca_find_autoload(name); /* No change asking for existing value */ if (ca == icsk->icsk_ca_ops) { icsk->icsk_ca_setsockopt = 1; goto out; } - if (!ca) + if (!ca) { err = -ENOENT; - else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || - ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))) + } else if (!load) { + icsk->icsk_ca_ops = ca; + if (!try_module_get(ca->owner)) + err = -EBUSY; + } else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || + ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))) { err = -EPERM; - else if (!try_module_get(ca->owner)) + } else if (!try_module_get(ca->owner)) { err = -EBUSY; - else + } else { tcp_reinit_congestion_control(sk, ca); + } out: rcu_read_unlock(); return err; diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 1b868ae..23f9707 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -6192,7 +6192,8 @@ static void tcp_ecn_create_request(struct request_sock *req, ecn_ok = net->ipv4.sysctl_tcp_ecn || ecn_ok_dst; if ((!ect && ecn_ok) || tcp_ca_needs_ecn(listen_sk) || - (ecn_ok_dst & DST_FEATURE_ECN_CA)) + (ecn_ok_dst & DST_FEATURE_ECN_CA) || + tcp_bpf_ca_needs_ecn((struct sock *)req)) inet_rsk(req)->ecn_ok = 1; } diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 958edc8..a273117 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -316,7 +316,8 @@ static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; if (!(tp->ecn_flags & TCP_ECN_OK)) TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; - else if (tcp_ca_needs_ecn(sk)) + else if (tcp_ca_needs_ecn(sk) || + tcp_bpf_ca_needs_ecn(sk)) INET_ECN_xmit(sk); } @@ -324,8 +325,9 @@ static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) { struct tcp_sock *tp = tcp_sk(sk); + bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk); bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 || - tcp_ca_needs_ecn(sk); + tcp_ca_needs_ecn(sk) || bpf_needs_ecn; if (!use_ecn) { const struct dst_entry *dst = __sk_dst_get(sk); @@ -339,7 +341,7 @@ static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) if (use_ecn) { TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; tp->ecn_flags = TCP_ECN_OK; - if (tcp_ca_needs_ecn(sk)) + if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) INET_ECN_xmit(sk); } } -- 2.9.3