- Add some helper hook points to the TCP stack. The hooks allow Khelp modules to

  access inbound/outbound events and associated data for established TCP
  connections. The hooks only run if at least one hook function is registered
  for the hook point, ensuring the impact on the stack is effectively nil when
  no TCP Khelp modules are loaded. struct tcp_hhook_data is passed as contextual
  data to any registered Khelp module hook functions.

- Add an OSD (Object Specific Data) pointer to struct tcpcb to allow Khelp
  modules to associate per-connection data with the TCP control block.

- Bump __FreeBSD_version and add a note to UPDATING regarding to ABI changes
  introduced by this commit and r216753.

In collaboration with:	David Hayes <dahayes at swin edu au> and
				Grenville Armitage <garmitage at swin edu au>
Sponsored by:	FreeBSD Foundation
Reviewed by:	bz, others along the way
MFC after:	3 months

5 files changed, 98 insertions, 1 deletions

diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
index 4dbc038..e2be41a 100644
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -54,6 +54,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
+#include <sys/hhook.h>
 #include <sys/malloc.h>
 #include <sys/mbuf.h>
 #include <sys/proc.h>		/* for proc0 declaration */
@@ -218,6 +219,8 @@ static void inline	cc_ack_received(struct tcpcb *tp, struct tcphdr *th,
 			    uint16_t type);
 static void inline	cc_conn_init(struct tcpcb *tp);
 static void inline	cc_post_recovery(struct tcpcb *tp, struct tcphdr *th);
+static void inline	hhook_run_tcp_est_in(struct tcpcb *tp,
+			    struct tcphdr *th, struct tcpopt *to);
 
 /*
  * Kernel module interface for updating tcpstat.  The argument is an index
@@ -234,6 +237,24 @@ kmod_tcpstat_inc(int statnum)
 }
 
 /*
+ * Wrapper for the TCP established input helper hook.
+ */
+static void inline
+hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to)
+{
+	struct tcp_hhook_data hhook_data;
+
+	if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) {
+		hhook_data.tp = tp;
+		hhook_data.th = th;
+		hhook_data.to = to;
+
+		hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data,
+		    tp->osd);
+	}
+}
+
+/*
  * CC wrapper hook functions
  */
 static void inline
@@ -1486,6 +1507,10 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
 							ticks - tp->t_rtttime);
 				}
 				acked = BYTES_THIS_ACK(tp, th);
+
+				/* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */
+				hhook_run_tcp_est_in(tp, th, &to);
+
 				TCPSTAT_INC(tcps_rcvackpack);
 				TCPSTAT_ADD(tcps_rcvackbyte, acked);
 				sbdrop(&so->so_snd, acked);
@@ -2199,6 +2224,10 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
 		    ((to.to_flags & TOF_SACK) ||
 		     !TAILQ_EMPTY(&tp->snd_holes)))
 			tcp_sack_doack(tp, &to, th->th_ack);
+
+		/* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */
+		hhook_run_tcp_est_in(tp, th, &to);
+
 		if (SEQ_LEQ(th->th_ack, tp->snd_una)) {
 			if (tlen == 0 && tiwin == tp->snd_wnd) {
 				TCPSTAT_INC(tcps_rcvdupack);
diff --git a/sys/netinet/tcp_output.c b/sys/netinet/tcp_output.c
index b7ec6f7..55d3c8e 100644
--- a/sys/netinet/tcp_output.c
+++ b/sys/netinet/tcp_output.c
@@ -40,6 +40,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/domain.h>
+#include <sys/hhook.h>
 #include <sys/kernel.h>
 #include <sys/lock.h>
 #include <sys/mbuf.h>
@@ -126,9 +127,33 @@ SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, sendbuf_max, CTLFLAG_RW,
 	&VNET_NAME(tcp_autosndbuf_max), 0,
 	"Max size of automatic send buffer");
 
+static void inline	hhook_run_tcp_est_out(struct tcpcb *tp,
+			    struct tcphdr *th, struct tcpopt *to,
+			    long len, int tso);
 static void inline	cc_after_idle(struct tcpcb *tp);
 
 /*
+ * Wrapper for the TCP established ouput helper hook.
+ */
+static void inline
+hhook_run_tcp_est_out(struct tcpcb *tp, struct tcphdr *th,
+    struct tcpopt *to, long len, int tso)
+{
+	struct tcp_hhook_data hhook_data;
+
+	if (V_tcp_hhh[HHOOK_TCP_EST_OUT]->hhh_nhooks > 0) {
+		hhook_data.tp = tp;
+		hhook_data.th = th;
+		hhook_data.to = to;
+		hhook_data.len = len;
+		hhook_data.tso = tso;
+
+		hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_OUT], &hhook_data,
+		    tp->osd);
+	}
+}
+
+/*
  * CC wrapper hook functions
  */
 static void inline
@@ -1134,6 +1159,9 @@ timer:
 			tp->snd_max = tp->snd_nxt + len;
 	}
 
+	/* Run HHOOK_TCP_ESTABLISHED_OUT helper hooks. */
+	hhook_run_tcp_est_out(tp, th, &to, len, tso);
+
 #ifdef TCPDEBUG
 	/*
 	 * Trace.
diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index 7345661..00d266d 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -41,7 +41,9 @@ __FBSDID("$FreeBSD$");
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/callout.h>
+#include <sys/hhook.h>
 #include <sys/kernel.h>
+#include <sys/khelp.h>
 #include <sys/sysctl.h>
 #include <sys/jail.h>
 #include <sys/malloc.h>
@@ -214,6 +216,8 @@ SYSCTL_INT(_net_inet_tcp, OID_AUTO, soreceive_stream, CTLFLAG_RDTUN,
 VNET_DEFINE(uma_zone_t, sack_hole_zone);
 #define	V_sack_hole_zone		VNET(sack_hole_zone)
 
+VNET_DEFINE(struct hhook_head *, tcp_hhh[HHOOK_TCP_LAST+1]);
+
 static struct inpcb *tcp_notify(struct inpcb *, int);
 static void	tcp_isn_tick(void *);
 static char *	tcp_log_addr(struct in_conninfo *inc, struct tcphdr *th,
@@ -239,6 +243,7 @@ struct tcpcb_mem {
 	struct	tcpcb		tcb;
 	struct	tcp_timer	tt;
 	struct	cc_var		ccv;
+	struct	osd		osd;
 };
 
 static VNET_DEFINE(uma_zone_t, tcpcb_zone);
@@ -278,6 +283,13 @@ tcp_init(void)
 {
 	int hashsize;
 
+	if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_IN,
+	    &V_tcp_hhh[HHOOK_TCP_EST_IN], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
+		printf("%s: WARNING: unable to register helper hook\n", __func__);
+	if (hhook_head_register(HHOOK_TYPE_TCP, HHOOK_TCP_EST_OUT,
+	    &V_tcp_hhh[HHOOK_TCP_EST_OUT], HHOOK_NOWAIT|HHOOK_HEADISINVNET) != 0)
+		printf("%s: WARNING: unable to register helper hook\n", __func__);
+
 	hashsize = TCBHASHSIZE;
 	TUNABLE_INT_FETCH("net.inet.tcp.tcbhashsize", &hashsize);
 	if (!powerof2(hashsize)) {
@@ -661,6 +673,12 @@ tcp_newtcpcb(struct inpcb *inp)
 			return (NULL);
 		}
 
+	tp->osd = &tm->osd;
+	if (khelp_init_osd(HELPER_CLASS_TCP, tp->osd)) {
+		uma_zfree(V_tcpcb_zone, tm);
+		return (NULL);
+	}
+
 #ifdef VIMAGE
 	tp->t_vnet = inp->inp_vnet;
 #endif
@@ -894,6 +912,8 @@ tcp_discardcb(struct tcpcb *tp)
 	if (CC_ALGO(tp)->cb_destroy != NULL)
 		CC_ALGO(tp)->cb_destroy(tp->ccv);
 
+	khelp_destroy_osd(tp->osd);
+
 	CC_ALGO(tp) = NULL;
 	inp->inp_ppcb = NULL;
 	tp->t_inpcb = NULL;
diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h
index 3305b1a..4a43213 100644
--- a/sys/netinet/tcp_var.h
+++ b/sys/netinet/tcp_var.h
@@ -201,6 +201,7 @@ struct tcpcb {
 	int	t_bytes_acked;		/* # bytes acked during current RTT */
 	struct cc_algo	*cc_algo;	/* congestion control algorithm */
 	struct cc_var	*ccv;
+	struct osd	*osd;		/* storage for Khelp module data */
 
 	int	t_ispare;		/* explicit pad for 64bit alignment */
 	void	*t_pspare2[4];		/* 4 TBD */
@@ -501,6 +502,22 @@ struct	tcpstat {
 void	kmod_tcpstat_inc(int statnum);
 #define	KMOD_TCPSTAT_INC(name)						\
 	kmod_tcpstat_inc(offsetof(struct tcpstat, name) / sizeof(u_long))
+
+/*
+ * TCP specific helper hook point identifiers.
+ */
+#define	HHOOK_TCP_EST_IN		0
+#define	HHOOK_TCP_EST_OUT		1
+#define	HHOOK_TCP_LAST			HHOOK_TCP_EST_OUT
+
+struct tcp_hhook_data {
+	struct tcpcb *tp;
+	struct tcphdr *th;
+	struct tcpopt *to;
+	long len;
+	int tso;
+	tcp_seq  curack;
+};
 #endif
 
 /*
@@ -608,6 +625,9 @@ VNET_DECLARE(int, tcp_ecn_maxretries);
 #define	V_tcp_do_ecn		VNET(tcp_do_ecn)
 #define	V_tcp_ecn_maxretries	VNET(tcp_ecn_maxretries)
 
+VNET_DECLARE(struct hhook_head *, tcp_hhh[HHOOK_TCP_LAST+1]);
+#define	V_tcp_hhh		VNET(tcp_hhh)
+
 int	 tcp_addoptions(struct tcpopt *, u_char *);
 int	 tcp_ccalgounload(struct cc_algo *unload_algo);
 struct tcpcb *
diff --git a/sys/sys/param.h b/sys/sys/param.h
index 29114d3..7ccd3ea 100644
--- a/sys/sys/param.h
+++ b/sys/sys/param.h
@@ -58,7 +58,7 @@
  *		in the range 5 to 9.
  */
 #undef __FreeBSD_version
-#define __FreeBSD_version 900028	/* Master, propagated to newvers */
+#define __FreeBSD_version 900029	/* Master, propagated to newvers */
 
 #ifdef _KERNEL
 #define	P_OSREL_SIGSEGV		700004