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 | 18 +++++++++++++++++-
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, 58 insertions(+), 17 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index d6bb394..7048329 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1004,7 +1004,9 @@ 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);
@@ -2078,4 +2080,9 @@ static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
rwnd = 0;
return rwnd;
}
+
+static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
+{
+ return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN) == 1);
+}
#endif /* _TCP_H */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 2405fe3..cc47259 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -778,6 +778,9 @@ 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 ca033e15..12df527 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2719,8 +2719,24 @@ 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 */
+#ifdef CONFIG_INET
+ if (optname == TCP_CONGESTION) {
+ char name[TCP_CA_NAME_MAX];
+
+ strncpy(name, optval, min_t(long, optlen,
+ TCP_CA_NAME_MAX-1));
+ name[TCP_CA_NAME_MAX-1] = 0;
+ ret = tcp_set_congestion_control(sk, name, 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;
+#endif
} else {
ret = -EINVAL;
}
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 4c88d20..5199952 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 664210e..2920e0c 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6191,7 +6191,8 @@ 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 76a1a0e..772a4f6 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
