1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * File: pep-gprs.c
4 *
5 * GPRS over Phonet pipe end point socket
6 *
7 * Copyright (C) 2008 Nokia Corporation.
8 *
9 * Author: Rémi Denis-Courmont
10 */
11
12#include <linux/kernel.h>
13#include <linux/netdevice.h>
14#include <linux/if_ether.h>
15#include <linux/if_arp.h>
16#include <net/sock.h>
17
18#include <linux/if_phonet.h>
19#include <net/tcp_states.h>
20#include <net/phonet/gprs.h>
21
22#include <trace/events/sock.h>
23
24#define GPRS_DEFAULT_MTU 1400
25
26struct gprs_dev {
27 struct sock *sk;
28 void (*old_state_change)(struct sock *);
29 void (*old_data_ready)(struct sock *);
30 void (*old_write_space)(struct sock *);
31
32 struct net_device *dev;
33};
34
35static __be16 gprs_type_trans(struct sk_buff *skb)
36{
37 const u8 *pvfc;
38 u8 buf;
39
40 pvfc = skb_header_pointer(skb, offset: 0, len: 1, buffer: &buf);
41 if (!pvfc)
42 return htons(0);
43 /* Look at IP version field */
44 switch (*pvfc >> 4) {
45 case 4:
46 return htons(ETH_P_IP);
47 case 6:
48 return htons(ETH_P_IPV6);
49 }
50 return htons(0);
51}
52
53static void gprs_writeable(struct gprs_dev *gp)
54{
55 struct net_device *dev = gp->dev;
56
57 if (pep_writeable(sk: gp->sk))
58 netif_wake_queue(dev);
59}
60
61/*
62 * Socket callbacks
63 */
64
65static void gprs_state_change(struct sock *sk)
66{
67 struct gprs_dev *gp = sk->sk_user_data;
68
69 if (sk->sk_state == TCP_CLOSE_WAIT) {
70 struct net_device *dev = gp->dev;
71
72 netif_stop_queue(dev);
73 netif_carrier_off(dev);
74 }
75}
76
77static int gprs_recv(struct gprs_dev *gp, struct sk_buff *skb)
78{
79 struct net_device *dev = gp->dev;
80 int err = 0;
81 __be16 protocol = gprs_type_trans(skb);
82
83 if (!protocol) {
84 err = -EINVAL;
85 goto drop;
86 }
87
88 if (skb_headroom(skb) & 3) {
89 struct sk_buff *rskb, *fs;
90 int flen = 0;
91
92 /* Phonet Pipe data header may be misaligned (3 bytes),
93 * so wrap the IP packet as a single fragment of an head-less
94 * socket buffer. The network stack will pull what it needs,
95 * but at least, the whole IP payload is not memcpy'd. */
96 rskb = netdev_alloc_skb(dev, length: 0);
97 if (!rskb) {
98 err = -ENOBUFS;
99 goto drop;
100 }
101 skb_shinfo(rskb)->frag_list = skb;
102 rskb->len += skb->len;
103 rskb->data_len += rskb->len;
104 rskb->truesize += rskb->len;
105
106 /* Avoid nested fragments */
107 skb_walk_frags(skb, fs)
108 flen += fs->len;
109 skb->next = skb_shinfo(skb)->frag_list;
110 skb_frag_list_init(skb);
111 skb->len -= flen;
112 skb->data_len -= flen;
113 skb->truesize -= flen;
114
115 skb = rskb;
116 }
117
118 skb->protocol = protocol;
119 skb_reset_mac_header(skb);
120 skb->dev = dev;
121
122 if (likely(dev->flags & IFF_UP)) {
123 dev->stats.rx_packets++;
124 dev->stats.rx_bytes += skb->len;
125 netif_rx(skb);
126 skb = NULL;
127 } else
128 err = -ENODEV;
129
130drop:
131 if (skb) {
132 dev_kfree_skb(skb);
133 dev->stats.rx_dropped++;
134 }
135 return err;
136}
137
138static void gprs_data_ready(struct sock *sk)
139{
140 struct gprs_dev *gp = sk->sk_user_data;
141 struct sk_buff *skb;
142
143 trace_sk_data_ready(sk);
144
145 while ((skb = pep_read(sk)) != NULL) {
146 skb_orphan(skb);
147 gprs_recv(gp, skb);
148 }
149}
150
151static void gprs_write_space(struct sock *sk)
152{
153 struct gprs_dev *gp = sk->sk_user_data;
154
155 if (netif_running(dev: gp->dev))
156 gprs_writeable(gp);
157}
158
159/*
160 * Network device callbacks
161 */
162
163static int gprs_open(struct net_device *dev)
164{
165 struct gprs_dev *gp = netdev_priv(dev);
166
167 gprs_writeable(gp);
168 return 0;
169}
170
171static int gprs_close(struct net_device *dev)
172{
173 netif_stop_queue(dev);
174 return 0;
175}
176
177static netdev_tx_t gprs_xmit(struct sk_buff *skb, struct net_device *dev)
178{
179 struct gprs_dev *gp = netdev_priv(dev);
180 struct sock *sk = gp->sk;
181 int len, err;
182
183 switch (skb->protocol) {
184 case htons(ETH_P_IP):
185 case htons(ETH_P_IPV6):
186 break;
187 default:
188 dev_kfree_skb(skb);
189 return NETDEV_TX_OK;
190 }
191
192 skb_orphan(skb);
193 skb_set_owner_w(skb, sk);
194 len = skb->len;
195 err = pep_write(sk, skb);
196 if (err) {
197 net_dbg_ratelimited("%s: TX error (%d)\n", dev->name, err);
198 dev->stats.tx_aborted_errors++;
199 dev->stats.tx_errors++;
200 } else {
201 dev->stats.tx_packets++;
202 dev->stats.tx_bytes += len;
203 }
204
205 netif_stop_queue(dev);
206 if (pep_writeable(sk))
207 netif_wake_queue(dev);
208 return NETDEV_TX_OK;
209}
210
211static const struct net_device_ops gprs_netdev_ops = {
212 .ndo_open = gprs_open,
213 .ndo_stop = gprs_close,
214 .ndo_start_xmit = gprs_xmit,
215};
216
217static void gprs_setup(struct net_device *dev)
218{
219 dev->features = NETIF_F_FRAGLIST;
220 dev->type = ARPHRD_PHONET_PIPE;
221 dev->flags = IFF_POINTOPOINT | IFF_NOARP;
222 dev->mtu = GPRS_DEFAULT_MTU;
223 dev->min_mtu = 576;
224 dev->max_mtu = (PHONET_MAX_MTU - 11);
225 dev->hard_header_len = 0;
226 dev->addr_len = 0;
227 dev->tx_queue_len = 10;
228
229 dev->netdev_ops = &gprs_netdev_ops;
230 dev->needs_free_netdev = true;
231}
232
233/*
234 * External interface
235 */
236
237/*
238 * Attach a GPRS interface to a datagram socket.
239 * Returns the interface index on success, negative error code on error.
240 */
241int gprs_attach(struct sock *sk)
242{
243 static const char ifname[] = "gprs%d";
244 struct gprs_dev *gp;
245 struct net_device *dev;
246 int err;
247
248 if (unlikely(sk->sk_type == SOCK_STREAM))
249 return -EINVAL; /* need packet boundaries */
250
251 /* Create net device */
252 dev = alloc_netdev(sizeof(*gp), ifname, NET_NAME_UNKNOWN, gprs_setup);
253 if (!dev)
254 return -ENOMEM;
255 gp = netdev_priv(dev);
256 gp->sk = sk;
257 gp->dev = dev;
258
259 netif_stop_queue(dev);
260 err = register_netdev(dev);
261 if (err) {
262 free_netdev(dev);
263 return err;
264 }
265
266 lock_sock(sk);
267 if (unlikely(sk->sk_user_data)) {
268 err = -EBUSY;
269 goto out_rel;
270 }
271 if (unlikely((1 << sk->sk_state & (TCPF_CLOSE|TCPF_LISTEN)) ||
272 sock_flag(sk, SOCK_DEAD))) {
273 err = -EINVAL;
274 goto out_rel;
275 }
276 sk->sk_user_data = gp;
277 gp->old_state_change = sk->sk_state_change;
278 gp->old_data_ready = sk->sk_data_ready;
279 gp->old_write_space = sk->sk_write_space;
280 sk->sk_state_change = gprs_state_change;
281 sk->sk_data_ready = gprs_data_ready;
282 sk->sk_write_space = gprs_write_space;
283 release_sock(sk);
284 sock_hold(sk);
285
286 printk(KERN_DEBUG"%s: attached\n", dev->name);
287 return dev->ifindex;
288
289out_rel:
290 release_sock(sk);
291 unregister_netdev(dev);
292 return err;
293}
294
295void gprs_detach(struct sock *sk)
296{
297 struct gprs_dev *gp = sk->sk_user_data;
298 struct net_device *dev = gp->dev;
299
300 lock_sock(sk);
301 sk->sk_user_data = NULL;
302 sk->sk_state_change = gp->old_state_change;
303 sk->sk_data_ready = gp->old_data_ready;
304 sk->sk_write_space = gp->old_write_space;
305 release_sock(sk);
306
307 printk(KERN_DEBUG"%s: detached\n", dev->name);
308 unregister_netdev(dev);
309 sock_put(sk);
310}
311

source code of linux/net/phonet/pep-gprs.c