1 /*
2  * llc_if.c - Defines LLC interface to upper layer
3  *
4  * Copyright (c) 1997 by Procom Technology, Inc.
5  * 		 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
6  *
7  * This program can be redistributed or modified under the terms of the
8  * GNU General Public License as published by the Free Software Foundation.
9  * This program is distributed without any warranty or implied warranty
10  * of merchantability or fitness for a particular purpose.
11  *
12  * See the GNU General Public License for more details.
13  */
14 #include <linux/gfp.h>
15 #include <linux/module.h>
16 #include <linux/kernel.h>
17 #include <linux/netdevice.h>
18 #include <asm/errno.h>
19 #include <net/llc_if.h>
20 #include <net/llc_sap.h>
21 #include <net/llc_s_ev.h>
22 #include <net/llc_conn.h>
23 #include <net/sock.h>
24 #include <net/llc_c_ev.h>
25 #include <net/llc_c_ac.h>
26 #include <net/llc_c_st.h>
27 #include <net/tcp_states.h>
28 
29 /**
30  *	llc_build_and_send_pkt - Connection data sending for upper layers.
31  *	@sk: connection
32  *	@skb: packet to send
33  *
34  *	This function is called when upper layer wants to send data using
35  *	connection oriented communication mode. During sending data, connection
36  *	will be locked and received frames and expired timers will be queued.
37  *	Returns 0 for success, -ECONNABORTED when the connection already
38  *	closed and -EBUSY when sending data is not permitted in this state or
39  *	LLC has send an I pdu with p bit set to 1 and is waiting for it's
40  *	response.
41  */
llc_build_and_send_pkt(struct sock * sk,struct sk_buff * skb)42 int llc_build_and_send_pkt(struct sock *sk, struct sk_buff *skb)
43 {
44 	struct llc_conn_state_ev *ev;
45 	int rc = -ECONNABORTED;
46 	struct llc_sock *llc = llc_sk(sk);
47 
48 	if (unlikely(llc->state == LLC_CONN_STATE_ADM))
49 		goto out;
50 	rc = -EBUSY;
51 	if (unlikely(llc_data_accept_state(llc->state) || /* data_conn_refuse */
52 		     llc->p_flag)) {
53 		llc->failed_data_req = 1;
54 		goto out;
55 	}
56 	ev = llc_conn_ev(skb);
57 	ev->type      = LLC_CONN_EV_TYPE_PRIM;
58 	ev->prim      = LLC_DATA_PRIM;
59 	ev->prim_type = LLC_PRIM_TYPE_REQ;
60 	skb->dev      = llc->dev;
61 	rc = llc_conn_state_process(sk, skb);
62 out:
63 	return rc;
64 }
65 
66 /**
67  *	llc_establish_connection - Called by upper layer to establish a conn
68  *	@sk: connection
69  *	@lmac: local mac address
70  *	@dmac: destination mac address
71  *	@dsap: destination sap
72  *
73  *	Upper layer calls this to establish an LLC connection with a remote
74  *	machine. This function packages a proper event and sends it connection
75  *	component state machine. Success or failure of connection
76  *	establishment will inform to upper layer via calling it's confirm
77  *	function and passing proper information.
78  */
llc_establish_connection(struct sock * sk,u8 * lmac,u8 * dmac,u8 dsap)79 int llc_establish_connection(struct sock *sk, u8 *lmac, u8 *dmac, u8 dsap)
80 {
81 	int rc = -EISCONN;
82 	struct llc_addr laddr, daddr;
83 	struct sk_buff *skb;
84 	struct llc_sock *llc = llc_sk(sk);
85 	struct sock *existing;
86 
87 	laddr.lsap = llc->sap->laddr.lsap;
88 	daddr.lsap = dsap;
89 	memcpy(daddr.mac, dmac, sizeof(daddr.mac));
90 	memcpy(laddr.mac, lmac, sizeof(laddr.mac));
91 	existing = llc_lookup_established(llc->sap, &daddr, &laddr);
92 	if (existing) {
93 		if (existing->sk_state == TCP_ESTABLISHED) {
94 			sk = existing;
95 			goto out_put;
96 		} else
97 			sock_put(existing);
98 	}
99 	sock_hold(sk);
100 	rc = -ENOMEM;
101 	skb = alloc_skb(0, GFP_ATOMIC);
102 	if (skb) {
103 		struct llc_conn_state_ev *ev = llc_conn_ev(skb);
104 
105 		ev->type      = LLC_CONN_EV_TYPE_PRIM;
106 		ev->prim      = LLC_CONN_PRIM;
107 		ev->prim_type = LLC_PRIM_TYPE_REQ;
108 		skb_set_owner_w(skb, sk);
109 		rc = llc_conn_state_process(sk, skb);
110 	}
111 out_put:
112 	sock_put(sk);
113 	return rc;
114 }
115 
116 /**
117  *	llc_send_disc - Called by upper layer to close a connection
118  *	@sk: connection to be closed
119  *
120  *	Upper layer calls this when it wants to close an established LLC
121  *	connection with a remote machine. This function packages a proper event
122  *	and sends it to connection component state machine. Returns 0 for
123  *	success, 1 otherwise.
124  */
llc_send_disc(struct sock * sk)125 int llc_send_disc(struct sock *sk)
126 {
127 	u16 rc = 1;
128 	struct llc_conn_state_ev *ev;
129 	struct sk_buff *skb;
130 
131 	sock_hold(sk);
132 	if (sk->sk_type != SOCK_STREAM || sk->sk_state != TCP_ESTABLISHED ||
133 	    llc_sk(sk)->state == LLC_CONN_STATE_ADM ||
134 	    llc_sk(sk)->state == LLC_CONN_OUT_OF_SVC)
135 		goto out;
136 	/*
137 	 * Postpone unassigning the connection from its SAP and returning the
138 	 * connection until all ACTIONs have been completely executed
139 	 */
140 	skb = alloc_skb(0, GFP_ATOMIC);
141 	if (!skb)
142 		goto out;
143 	skb_set_owner_w(skb, sk);
144 	sk->sk_state  = TCP_CLOSING;
145 	ev	      = llc_conn_ev(skb);
146 	ev->type      = LLC_CONN_EV_TYPE_PRIM;
147 	ev->prim      = LLC_DISC_PRIM;
148 	ev->prim_type = LLC_PRIM_TYPE_REQ;
149 	rc = llc_conn_state_process(sk, skb);
150 out:
151 	sock_put(sk);
152 	return rc;
153 }
154 
155