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/net/x25/x25_dev.c

http://github.com/mirrors/linux
C | 229 lines | 157 code | 39 blank | 33 comment | 29 complexity | 725bd1fa0e2374a46172e9e0fc7fb1f1 MD5 | raw file
  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 *	X.25 Packet Layer release 002
  4 *
  5 *	This is ALPHA test software. This code may break your machine, randomly fail to work with new
  6 *	releases, misbehave and/or generally screw up. It might even work.
  7 *
  8 *	This code REQUIRES 2.1.15 or higher
  9 *
 10 *	History
 11 *	X.25 001	Jonathan Naylor	Started coding.
 12 *      2000-09-04	Henner Eisen	Prevent freeing a dangling skb.
 13 */
 14
 15#define pr_fmt(fmt) "X25: " fmt
 16
 17#include <linux/kernel.h>
 18#include <linux/netdevice.h>
 19#include <linux/skbuff.h>
 20#include <linux/slab.h>
 21#include <net/sock.h>
 22#include <linux/if_arp.h>
 23#include <net/x25.h>
 24#include <net/x25device.h>
 25
 26static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
 27{
 28	struct sock *sk;
 29	unsigned short frametype;
 30	unsigned int lci;
 31
 32	if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
 33		return 0;
 34
 35	frametype = skb->data[2];
 36	lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
 37
 38	/*
 39	 *	LCI of zero is always for us, and its always a link control
 40	 *	frame.
 41	 */
 42	if (lci == 0) {
 43		x25_link_control(skb, nb, frametype);
 44		return 0;
 45	}
 46
 47	/*
 48	 *	Find an existing socket.
 49	 */
 50	if ((sk = x25_find_socket(lci, nb)) != NULL) {
 51		int queued = 1;
 52
 53		skb_reset_transport_header(skb);
 54		bh_lock_sock(sk);
 55		if (!sock_owned_by_user(sk)) {
 56			queued = x25_process_rx_frame(sk, skb);
 57		} else {
 58			queued = !sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf));
 59		}
 60		bh_unlock_sock(sk);
 61		sock_put(sk);
 62		return queued;
 63	}
 64
 65	/*
 66	 *	Is is a Call Request ? if so process it.
 67	 */
 68	if (frametype == X25_CALL_REQUEST)
 69		return x25_rx_call_request(skb, nb, lci);
 70
 71	/*
 72	 * 	Its not a Call Request, nor is it a control frame.
 73	 *	Can we forward it?
 74	 */
 75
 76	if (x25_forward_data(lci, nb, skb)) {
 77		if (frametype == X25_CLEAR_CONFIRMATION) {
 78			x25_clear_forward_by_lci(lci);
 79		}
 80		kfree_skb(skb);
 81		return 1;
 82	}
 83
 84/*
 85	x25_transmit_clear_request(nb, lci, 0x0D);
 86*/
 87
 88	if (frametype != X25_CLEAR_CONFIRMATION)
 89		pr_debug("x25_receive_data(): unknown frame type %2x\n",frametype);
 90
 91	return 0;
 92}
 93
 94int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
 95			   struct packet_type *ptype, struct net_device *orig_dev)
 96{
 97	struct sk_buff *nskb;
 98	struct x25_neigh *nb;
 99
100	if (!net_eq(dev_net(dev), &init_net))
101		goto drop;
102
103	nskb = skb_copy(skb, GFP_ATOMIC);
104	if (!nskb)
105		goto drop;
106	kfree_skb(skb);
107	skb = nskb;
108
109	/*
110	 * Packet received from unrecognised device, throw it away.
111	 */
112	nb = x25_get_neigh(dev);
113	if (!nb) {
114		pr_debug("unknown neighbour - %s\n", dev->name);
115		goto drop;
116	}
117
118	if (!pskb_may_pull(skb, 1)) {
119		x25_neigh_put(nb);
120		return 0;
121	}
122
123	switch (skb->data[0]) {
124
125	case X25_IFACE_DATA:
126		skb_pull(skb, 1);
127		if (x25_receive_data(skb, nb)) {
128			x25_neigh_put(nb);
129			goto out;
130		}
131		break;
132
133	case X25_IFACE_CONNECT:
134		x25_link_established(nb);
135		break;
136
137	case X25_IFACE_DISCONNECT:
138		x25_link_terminated(nb);
139		break;
140	}
141	x25_neigh_put(nb);
142drop:
143	kfree_skb(skb);
144out:
145	return 0;
146}
147
148void x25_establish_link(struct x25_neigh *nb)
149{
150	struct sk_buff *skb;
151	unsigned char *ptr;
152
153	switch (nb->dev->type) {
154	case ARPHRD_X25:
155		if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
156			pr_err("x25_dev: out of memory\n");
157			return;
158		}
159		ptr  = skb_put(skb, 1);
160		*ptr = X25_IFACE_CONNECT;
161		break;
162
163#if IS_ENABLED(CONFIG_LLC)
164	case ARPHRD_ETHER:
165		return;
166#endif
167	default:
168		return;
169	}
170
171	skb->protocol = htons(ETH_P_X25);
172	skb->dev      = nb->dev;
173
174	dev_queue_xmit(skb);
175}
176
177void x25_terminate_link(struct x25_neigh *nb)
178{
179	struct sk_buff *skb;
180	unsigned char *ptr;
181
182#if IS_ENABLED(CONFIG_LLC)
183	if (nb->dev->type == ARPHRD_ETHER)
184		return;
185#endif
186	if (nb->dev->type != ARPHRD_X25)
187		return;
188
189	skb = alloc_skb(1, GFP_ATOMIC);
190	if (!skb) {
191		pr_err("x25_dev: out of memory\n");
192		return;
193	}
194
195	ptr  = skb_put(skb, 1);
196	*ptr = X25_IFACE_DISCONNECT;
197
198	skb->protocol = htons(ETH_P_X25);
199	skb->dev      = nb->dev;
200	dev_queue_xmit(skb);
201}
202
203void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
204{
205	unsigned char *dptr;
206
207	skb_reset_network_header(skb);
208
209	switch (nb->dev->type) {
210	case ARPHRD_X25:
211		dptr  = skb_push(skb, 1);
212		*dptr = X25_IFACE_DATA;
213		break;
214
215#if IS_ENABLED(CONFIG_LLC)
216	case ARPHRD_ETHER:
217		kfree_skb(skb);
218		return;
219#endif
220	default:
221		kfree_skb(skb);
222		return;
223	}
224
225	skb->protocol = htons(ETH_P_X25);
226	skb->dev      = nb->dev;
227
228	dev_queue_xmit(skb);
229}