Re: [PATCH v2 net-next 1/4] tcp: ULP infrastructure

[David Miller]

From: Dave Watson 
Date: Tue, 6 Jun 2017 10:00:20 -0700

> +EXPORT_SYMBOL(tcp_register_ulp);

EXPORT_SYMBOL_GPL() please.

> +EXPORT_SYMBOL(tcp_unregister_ulp);

Likewise.

[PATCH v2 net-next 1/4] tcp: ULP infrastructure

[Dave Watson]

Add the infrustructure for attaching Upper Layer Protocols (ULPs) over TCP
sockets. Based on a similar infrastructure in tcp_cong.  The idea is that any
ULP can add its own logic by changing the TCP proto_ops structure to its own
methods.

Example usage:

setsockopt(sock, SOL_TCP, TCP_ULP, "tls", sizeof("tls"));

modules will call:
tcp_register_ulp(_tls_ulp_ops);

to register/unregister their ulp, with an init function and name.

A list of registered ulps will be returned by tcp_get_available_ulp, which is
hooked up to /proc.  Example:

$ cat /proc/sys/net/ipv4/tcp_available_ulp
tls

There is currently no functionality to remove or chain ULPs, but
it should be possible to add these in the future if needed.

Signed-off-by: Boris Pismenny 
Signed-off-by: Dave Watson 
---
 include/net/inet_connection_sock.h |   4 ++
 include/net/tcp.h  |  25 +++
 include/uapi/linux/tcp.h   |   1 +
 net/ipv4/Makefile  |   2 +-
 net/ipv4/sysctl_net_ipv4.c |  25 +++
 net/ipv4/tcp.c |  28 
 net/ipv4/tcp_ipv4.c|   2 +
 net/ipv4/tcp_ulp.c | 134 +
 8 files changed, 220 insertions(+), 1 deletion(-)
 create mode 100644 net/ipv4/tcp_ulp.c

diff --git a/include/net/inet_connection_sock.h 
b/include/net/inet_connection_sock.h
index c7a5779..13e4c89 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -75,6 +75,8 @@ struct inet_connection_sock_af_ops {
  * @icsk_pmtu_cookie  Last pmtu seen by socket
  * @icsk_ca_ops   Pluggable congestion control hook
  * @icsk_af_ops   Operations which are AF_INET{4,6} specific
+ * @icsk_ulp_ops  Pluggable ULP control hook
+ * @icsk_ulp_data ULP private data
  * @icsk_ca_state:Congestion control state
  * @icsk_retransmits: Number of unrecovered [RTO] timeouts
  * @icsk_pending: Scheduled timer event
@@ -97,6 +99,8 @@ struct inet_connection_sock {
__u32 icsk_pmtu_cookie;
const struct tcp_congestion_ops *icsk_ca_ops;
const struct inet_connection_sock_af_ops *icsk_af_ops;
+   const struct tcp_ulp_ops  *icsk_ulp_ops;
+   void  *icsk_ulp_data;
unsigned int  (*icsk_sync_mss)(struct sock *sk, u32 pmtu);
__u8  icsk_ca_state:6,
  icsk_ca_setsockopt:1,
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 82462db..fcc39f8 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1992,4 +1992,29 @@ static inline void tcp_listendrop(const struct sock *sk)
 
 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
 
+/*
+ * Interface for adding Upper Level Protocols over TCP
+ */
+
+#define TCP_ULP_NAME_MAX   16
+#define TCP_ULP_MAX128
+#define TCP_ULP_BUF_MAX(TCP_ULP_NAME_MAX*TCP_ULP_MAX)
+
+struct tcp_ulp_ops {
+   struct list_headlist;
+
+   /* initialize ulp */
+   int (*init)(struct sock *sk);
+   /* cleanup ulp */
+   void (*release)(struct sock *sk);
+
+   charname[TCP_ULP_NAME_MAX];
+   struct module   *owner;
+};
+int tcp_register_ulp(struct tcp_ulp_ops *type);
+void tcp_unregister_ulp(struct tcp_ulp_ops *type);
+int tcp_set_ulp(struct sock *sk, const char *name);
+void tcp_get_available_ulp(char *buf, size_t len);
+void tcp_cleanup_ulp(struct sock *sk);
+
 #endif /* _TCP_H */
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 38a2b07..8204dce 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -117,6 +117,7 @@ enum {
 #define TCP_SAVED_SYN  28  /* Get SYN headers recorded for 
connection */
 #define TCP_REPAIR_WINDOW  29  /* Get/set window parameters */
 #define TCP_FASTOPEN_CONNECT   30  /* Attempt FastOpen with connect */
+#define TCP_ULP31  /* Attach a ULP to a TCP connection */
 
 struct tcp_repair_opt {
__u32   opt_code;
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index f83de23..afcb435 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -8,7 +8,7 @@ obj-y := route.o inetpeer.o protocol.o \
 inet_timewait_sock.o inet_connection_sock.o \
 tcp.o tcp_input.o tcp_output.o tcp_timer.o tcp_ipv4.o \
 tcp_minisocks.o tcp_cong.o tcp_metrics.o tcp_fastopen.o \
-tcp_rate.o tcp_recovery.o \
+tcp_rate.o tcp_recovery.o tcp_ulp.o \
 tcp_offload.o datagram.o raw.o udp.o udplite.o \
 udp_offload.o arp.o icmp.o devinet.o af_inet.o igmp.o \
 fib_frontend.o fib_semantics.o fib_trie.o fib_notifier.o \
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 86957e9..6a40837c 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -360,6 +360,25 @@