From: Peter Krystad <peter.krys...@linux.intel.com>
Add hooks to tcp_output.c to add MP_CAPABLE to an outgoing
SYN request for a subflow socket and to the final ACK of the
three-way handshake.
Use the .sk_rx_dst_set() handler in the subflow proto to capture
when the responding SYN-ACK is received and notify the MPTCP
connection layer.
Signed-off-by: Peter Krystad <peter.krys...@linux.intel.com>
---
include/net/mptcp.h | 35 ++++++++++++++++++++++++++++
net/ipv4/tcp_input.c | 3 +++
net/ipv4/tcp_output.c | 29 +++++++++++++++++++++--
net/mptcp/options.c | 45 ++++++++++++++++++++++++++++++++++++
net/mptcp/protocol.c | 53 +++++++++++++++++++++++++++++++------------
net/mptcp/protocol.h | 16 +++++++++++--
net/mptcp/subflow.c | 25 ++++++++++++++++++--
7 files changed, 185 insertions(+), 21 deletions(-)
diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 0d3e02c6c817..81255b0f57d7 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -14,17 +14,30 @@
#define OPTION_MPTCP_MPC_ACK BIT(2)
struct mptcp_out_options {
+#if IS_ENABLED(CONFIG_MPTCP)
u16 suboptions;
u64 sndr_key;
u64 rcvr_key;
+#endif
};
#ifdef CONFIG_MPTCP
void mptcp_init(void);
+static inline bool sk_is_mptcp(const struct sock *sk)
+{
+ return tcp_sk(sk)->is_mptcp;
+}
+
void mptcp_parse_option(const unsigned char *ptr, int opsize,
struct tcp_options_received *opt_rx);
+bool mptcp_syn_options(struct sock *sk, unsigned int *size,
+ struct mptcp_out_options *opts);
+void mptcp_rcv_synsent(struct sock *sk);
+bool mptcp_established_options(struct sock *sk, unsigned int *size,
+ struct mptcp_out_options *opts);
+
void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts);
#else
@@ -33,10 +46,32 @@ static inline void mptcp_init(void)
{
}
+static inline bool sk_is_mptcp(const struct sock *sk)
+{
+ return false;
+}
+
static inline void mptcp_parse_option(const unsigned char *ptr, int opsize,
struct tcp_options_received *opt_rx)
{
}
+static inline bool mptcp_syn_options(struct sock *sk, unsigned int *size,
+ struct mptcp_out_options *opts)
+{
+ return false;
+}
+
+static inline void mptcp_rcv_synsent(struct sock *sk)
+{
+}
+
+static inline bool mptcp_established_options(struct sock *sk,
+ unsigned int *size,
+ struct mptcp_out_options *opts)
+{
+ return false;
+}
+
#endif /* CONFIG_MPTCP */
#endif /* __NET_MPTCP_H */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 117f0efbbad5..4aa60fe0deca 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5901,6 +5901,9 @@ static int tcp_rcv_synsent_state_process(struct sock *sk,
struct sk_buff *skb,
tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
tcp_initialize_rcv_mss(sk);
+ if (sk_is_mptcp(sk))
+ mptcp_rcv_synsent(sk);
+
/* Remember, tcp_poll() does not lock socket!
* Change state from SYN-SENT only after copied_seq
* is initialized. */
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 69c4f39efe8b..f46e58347d73 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -438,9 +438,7 @@ struct tcp_out_options {
__u8 *hash_location; /* temporary pointer, overloaded */
__u32 tsval, tsecr; /* need to include OPTION_TS */
struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */
-#if IS_ENABLED(CONFIG_MPTCP)
struct mptcp_out_options mptcp;
-#endif
};
static void mptcp_options_write(__be32 *ptr, struct tcp_out_options *opts)
@@ -665,6 +663,15 @@ static unsigned int tcp_syn_options(struct sock *sk,
struct sk_buff *skb,
smc_set_option(tp, opts, &remaining);
+ if (sk_is_mptcp(sk)) {
+ unsigned int size;
+
+ if (mptcp_syn_options(sk, &size, &opts->mptcp)) {
+ opts->options |= OPTION_MPTCP;
+ remaining -= size;
+ }
+ }
+
return MAX_TCP_OPTION_SPACE - remaining;
}
@@ -763,6 +770,24 @@ static unsigned int tcp_established_options(struct sock
*sk, struct sk_buff *skb
size += TCPOLEN_TSTAMP_ALIGNED;
}
+ /* MPTCP options have precedence over SACK for the limited TCP
+ * option space because a MPTCP connection would be forced to
+ * fall back to regular TCP if a required multipath option is
+ * missing. SACK still gets a chance to use whatever space is
+ * left.
+ */
+ if (sk_is_mptcp(sk)) {
+ unsigned int remaining = MAX_TCP_OPTION_SPACE - size;
+ unsigned int opt_size;
+
+ if (mptcp_established_options(sk, &opt_size, &opts->mptcp)) {
+ if (remaining >= opt_size) {
+ opts->options |= OPTION_MPTCP;
+ size += opt_size;
+ }
+ }
+ }
+
eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack;
if (unlikely(eff_sacks)) {
const unsigned int remaining = MAX_TCP_OPTION_SPACE - size;
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 42626cd0a9f7..071e937d5c1f 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -121,6 +121,51 @@ void mptcp_parse_option(const unsigned char *ptr, int
opsize,
}
}
+bool mptcp_syn_options(struct sock *sk, unsigned int *size,
+ struct mptcp_out_options *opts)
+{
+ struct subflow_context *subflow = subflow_ctx(sk);
+
+ if (subflow->request_mptcp) {
+ pr_debug("local_key=%llu", subflow->local_key);
+ opts->suboptions = OPTION_MPTCP_MPC_SYN;
+ opts->sndr_key = subflow->local_key;
+ *size = TCPOLEN_MPTCP_MPC_SYN;
+ return true;
+ }
+ return false;
+}
+
+void mptcp_rcv_synsent(struct sock *sk)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct subflow_context *subflow = subflow_ctx(sk);
+
+ pr_debug("subflow=%p", subflow);
+ if (subflow->request_mptcp && tp->rx_opt.mptcp.mp_capable) {
+ subflow->mp_capable = 1;
+ subflow->remote_key = tp->rx_opt.mptcp.sndr_key;
+ }
+}
+
+bool mptcp_established_options(struct sock *sk, unsigned int *size,
+ struct mptcp_out_options *opts)
+{
+ struct subflow_context *subflow = subflow_ctx(sk);
+
+ if (subflow->mp_capable && !subflow->fourth_ack) {
+ opts->suboptions = OPTION_MPTCP_MPC_ACK;
+ opts->sndr_key = subflow->local_key;
+ opts->rcvr_key = subflow->remote_key;
+ *size = TCPOLEN_MPTCP_MPC_ACK;
+ subflow->fourth_ack = 1;
+ pr_debug("subflow=%p, local_key=%llu, remote_key=%llu",
+ subflow, subflow->local_key, subflow->remote_key);
+ return true;
+ }
+ return false;
+}
+
void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts)
{
if ((OPTION_MPTCP_MPC_SYN |
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index ce2374ea7871..56637e4474da 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -18,9 +18,15 @@
static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
{
struct mptcp_sock *msk = mptcp_sk(sk);
- struct socket *subflow = msk->subflow;
-
- pr_debug("subflow=%p", subflow_ctx(subflow->sk));
+ struct socket *subflow;
+
+ if (msk->connection_list) {
+ subflow = msk->connection_list;
+ pr_debug("conn_list->subflow=%p", subflow_ctx(subflow->sk));
+ } else {
+ subflow = msk->subflow;
+ pr_debug("subflow=%p", subflow_ctx(subflow->sk));
+ }
return sock_sendmsg(subflow, msg);
}
@@ -29,9 +35,15 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr
*msg, size_t len,
int nonblock, int flags, int *addr_len)
{
struct mptcp_sock *msk = mptcp_sk(sk);
- struct socket *subflow = msk->subflow;
-
- pr_debug("subflow=%p", subflow_ctx(subflow->sk));
+ struct socket *subflow;
+
+ if (msk->connection_list) {
+ subflow = msk->connection_list;
+ pr_debug("conn_list->subflow=%p", subflow_ctx(subflow->sk));
+ } else {
+ subflow = msk->subflow;
+ pr_debug("subflow=%p", subflow_ctx(subflow->sk));
+ }
return sock_recvmsg(subflow, msg, flags);
}
@@ -56,24 +68,36 @@ static void mptcp_close(struct sock *sk, long timeout)
sock_release(msk->subflow);
}
+ if (msk->connection_list) {
+ pr_debug("conn_list->subflow=%p", msk->connection_list->sk);
+ sock_release(msk->connection_list);
+ }
+
sock_orphan(sk);
sock_put(sk);
}
-static int mptcp_connect(struct sock *sk, struct sockaddr *saddr, int len)
+static int mptcp_get_port(struct sock *sk, unsigned short snum)
{
struct mptcp_sock *msk = mptcp_sk(sk);
- int err;
-
- saddr->sa_family = AF_INET;
pr_debug("msk=%p, subflow=%p", msk, subflow_ctx(msk->subflow->sk));
- err = kernel_connect(msk->subflow, saddr, len, 0);
+ return inet_csk_get_port(msk->subflow->sk, snum);
+}
- sk->sk_state = TCP_ESTABLISHED;
+void mptcp_finish_connect(struct sock *sk, int mp_capable)
+{
+ struct mptcp_sock *msk = mptcp_sk(sk);
+ struct subflow_context *subflow = subflow_ctx(msk->subflow->sk);
- return err;
+ if (mp_capable) {
+ msk->remote_key = subflow->remote_key;
+ msk->local_key = subflow->local_key;
+ msk->connection_list = msk->subflow;
+ msk->subflow = NULL;
+ }
+ sk->sk_state = TCP_ESTABLISHED;
}
static struct proto mptcp_prot = {
@@ -82,13 +106,12 @@ static struct proto mptcp_prot = {
.init = mptcp_init_sock,
.close = mptcp_close,
.accept = inet_csk_accept,
- .connect = mptcp_connect,
.shutdown = tcp_shutdown,
.sendmsg = mptcp_sendmsg,
.recvmsg = mptcp_recvmsg,
.hash = inet_hash,
.unhash = inet_unhash,
- .get_port = inet_csk_get_port,
+ .get_port = mptcp_get_port,
.obj_size = sizeof(struct mptcp_sock),
.no_autobind = 1,
};
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index b6adc2aa6222..9206e60ef6d3 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -33,7 +33,10 @@
struct mptcp_sock {
/* inet_connection_sock must be the first member */
struct inet_connection_sock sk;
- struct socket *subflow;
+ u64 local_key;
+ u64 remote_key;
+ struct socket *connection_list; /* @@ needs to be a list */
+ struct socket *subflow; /* outgoing connect, listener or !mp_capable */
};
static inline struct mptcp_sock *mptcp_sk(const struct sock *sk)
@@ -43,9 +46,14 @@ static inline struct mptcp_sock *mptcp_sk(const struct sock
*sk)
/* MPTCP subflow context */
struct subflow_context {
+ u64 local_key;
+ u64 remote_key;
u32 request_mptcp : 1, /* send MP_CAPABLE */
request_cksum : 1,
- version : 4;
+ mp_capable : 1, /* remote is MPTCP capable */
+ fourth_ack : 1, /* send initial DSS */
+ version : 4,
+ conn_finished : 1;
struct socket *tcp_sock; /* underlying tcp_sock */
struct sock *conn; /* parent mptcp_sock */
};
@@ -65,4 +73,8 @@ mptcp_subflow_tcp_socket(const struct subflow_context
*subflow)
void subflow_init(void);
+extern const struct inet_connection_sock_af_ops ipv4_specific;
+
+void mptcp_finish_connect(struct sock *sk, int mp_capable);
+
#endif /* __MPTCP_PROTOCOL_H */
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 8d13713ee159..91df2c4be339 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -15,6 +15,22 @@
#include <net/mptcp.h>
#include "protocol.h"
+static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
+{
+ struct subflow_context *subflow = subflow_ctx(sk);
+
+ inet_sk_rx_dst_set(sk, skb);
+
+ if (subflow->conn && !subflow->conn_finished) {
+ pr_debug("subflow=%p, remote_key=%llu", subflow_ctx(sk),
+ subflow->remote_key);
+ mptcp_finish_connect(subflow->conn, subflow->mp_capable);
+ subflow->conn_finished = 1;
+ }
+}
+
+static struct inet_connection_sock_af_ops subflow_specific;
+
static struct subflow_context *subflow_create_ctx(struct sock *sk,
struct socket *sock)
{
@@ -36,7 +52,8 @@ static struct subflow_context *subflow_create_ctx(struct sock
*sk,
static int subflow_ulp_init(struct sock *sk)
{
- struct tcp_sock *tsk = tcp_sk(sk);
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct inet_connection_sock *icsk = inet_csk(sk);
struct subflow_context *ctx;
int err = 0;
@@ -48,7 +65,8 @@ static int subflow_ulp_init(struct sock *sk)
pr_debug("subflow=%p", ctx);
- tsk->is_mptcp = 1;
+ tp->is_mptcp = 1;
+ icsk->icsk_af_ops = &subflow_specific;
out:
return err;
}
@@ -71,6 +89,9 @@ static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
void subflow_init(void)
{
+ subflow_specific = ipv4_specific;
+ subflow_specific.sk_rx_dst_set = subflow_finish_connect;
+
if (tcp_register_ulp(&subflow_ulp_ops) != 0)
panic("MPTCP: failed to register subflows to ULP\n");
}
--
2.22.0
