1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 *
4 * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
5 * Copyright Darryl Miles G7LED (dlm@g7led.demon.co.uk)
6 */
7 #include <linux/errno.h>
8 #include <linux/types.h>
9 #include <linux/socket.h>
10 #include <linux/in.h>
11 #include <linux/kernel.h>
12 #include <linux/timer.h>
13 #include <linux/string.h>
14 #include <linux/sockios.h>
15 #include <linux/net.h>
16 #include <linux/slab.h>
17 #include <net/ax25.h>
18 #include <linux/inet.h>
19 #include <linux/netdevice.h>
20 #include <linux/skbuff.h>
21 #include <net/sock.h>
22 #include <net/tcp_states.h>
23 #include <linux/uaccess.h>
24 #include <linux/fcntl.h>
25 #include <linux/mm.h>
26 #include <linux/interrupt.h>
27 #include <net/netrom.h>
28
29 static int nr_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
30 {
31 struct sk_buff *skbo, *skbn = skb;
32 struct nr_sock *nr = nr_sk(sk);
33
34 skb_pull(skb, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
35
36 nr_start_idletimer(sk);
37
38 if (more) {
39 nr->fraglen += skb->len;
40 skb_queue_tail(&nr->frag_queue, skb);
41 return 0;
42 }
43
44 if (!more && nr->fraglen > 0) { /* End of fragment */
45 nr->fraglen += skb->len;
46 skb_queue_tail(&nr->frag_queue, skb);
47
48 if ((skbn = alloc_skb(nr->fraglen, GFP_ATOMIC)) == NULL)
49 return 1;
50
51 skb_reset_transport_header(skbn);
52
53 while ((skbo = skb_dequeue(&nr->frag_queue)) != NULL) {
54 skb_copy_from_linear_data(skbo,
55 skb_put(skbn, skbo->len),
56 skbo->len);
57 kfree_skb(skbo);
58 }
59
60 nr->fraglen = 0;
61 }
62
63 return sock_queue_rcv_skb(sk, skbn);
64 }
65
66 /*
67 * State machine for state 1, Awaiting Connection State.
68 * The handling of the timer(s) is in file nr_timer.c.
69 * Handling of state 0 and connection release is in netrom.c.
70 */
71 static int nr_state1_machine(struct sock *sk, struct sk_buff *skb,
72 int frametype)
73 {
74 switch (frametype) {
75 case NR_CONNACK: {
76 struct nr_sock *nr = nr_sk(sk);
77
78 nr_stop_t1timer(sk);
79 nr_start_idletimer(sk);
80 nr->your_index = skb->data[17];
81 nr->your_id = skb->data[18];
82 nr->vs = 0;
83 nr->va = 0;
84 nr->vr = 0;
85 nr->vl = 0;
86 nr->state = NR_STATE_3;
87 nr->n2count = 0;
88 nr->window = skb->data[20];
89 sk->sk_state = TCP_ESTABLISHED;
90 if (!sock_flag(sk, SOCK_DEAD))
91 sk->sk_state_change(sk);
92 break;
93 }
94
95 case NR_CONNACK | NR_CHOKE_FLAG:
96 nr_disconnect(sk, ECONNREFUSED);
97 break;
98
99 case NR_RESET:
100 if (READ_ONCE(sysctl_netrom_reset_circuit))
101 nr_disconnect(sk, ECONNRESET);
102 break;
103
104 default:
105 break;
106 }
107 return 0;
108 }
109
110 /*
111 * State machine for state 2, Awaiting Release State.
112 * The handling of the timer(s) is in file nr_timer.c
113 * Handling of state 0 and connection release is in netrom.c.
114 */
115 static int nr_state2_machine(struct sock *sk, struct sk_buff *skb,
116 int frametype)
117 {
118 switch (frametype) {
119 case NR_CONNACK | NR_CHOKE_FLAG:
120 nr_disconnect(sk, ECONNRESET);
121 break;
122
123 case NR_DISCREQ:
124 nr_write_internal(sk, NR_DISCACK);
125 fallthrough;
126 case NR_DISCACK:
127 nr_disconnect(sk, 0);
128 break;
129
130 case NR_RESET:
131 if (READ_ONCE(sysctl_netrom_reset_circuit))
132 nr_disconnect(sk, ECONNRESET);
133 break;
134
135 default:
136 break;
137 }
138 return 0;
139 }
140
141 /*
142 * State machine for state 3, Connected State.
143 * The handling of the timer(s) is in file nr_timer.c
144 * Handling of state 0 and connection release is in netrom.c.
145 */
146 static int nr_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype)
147 {
148 struct nr_sock *nrom = nr_sk(sk);
149 struct sk_buff_head temp_queue;
150 struct sk_buff *skbn;
151 unsigned short save_vr;
152 unsigned short nr, ns;
153 int queued = 0;
154
155 nr = skb->data[18];
156
157 switch (frametype) {
158 case NR_CONNREQ:
159 nr_write_internal(sk, NR_CONNACK);
160 break;
161
162 case NR_DISCREQ:
163 nr_write_internal(sk, NR_DISCACK);
164 nr_disconnect(sk, 0);
165 break;
166
167 case NR_CONNACK | NR_CHOKE_FLAG:
168 case NR_DISCACK:
169 nr_disconnect(sk, ECONNRESET);
170 break;
171
172 case NR_INFOACK:
173 case NR_INFOACK | NR_CHOKE_FLAG:
174 case NR_INFOACK | NR_NAK_FLAG:
175 case NR_INFOACK | NR_NAK_FLAG | NR_CHOKE_FLAG:
176 if (frametype & NR_CHOKE_FLAG) {
177 nrom->condition |= NR_COND_PEER_RX_BUSY;
178 nr_start_t4timer(sk);
179 } else {
180 nrom->condition &= ~NR_COND_PEER_RX_BUSY;
181 nr_stop_t4timer(sk);
182 }
183 if (!nr_validate_nr(sk, nr)) {
184 break;
185 }
186 if (frametype & NR_NAK_FLAG) {
187 nr_frames_acked(sk, nr);
188 nr_send_nak_frame(sk);
189 } else {
190 if (nrom->condition & NR_COND_PEER_RX_BUSY) {
191 nr_frames_acked(sk, nr);
192 } else {
193 nr_check_iframes_acked(sk, nr);
194 }
195 }
196 break;
197
198 case NR_INFO:
199 case NR_INFO | NR_NAK_FLAG:
200 case NR_INFO | NR_CHOKE_FLAG:
201 case NR_INFO | NR_MORE_FLAG:
202 case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG:
203 case NR_INFO | NR_CHOKE_FLAG | NR_MORE_FLAG:
204 case NR_INFO | NR_NAK_FLAG | NR_MORE_FLAG:
205 case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG | NR_MORE_FLAG:
206 if (frametype & NR_CHOKE_FLAG) {
207 nrom->condition |= NR_COND_PEER_RX_BUSY;
208 nr_start_t4timer(sk);
209 } else {
210 nrom->condition &= ~NR_COND_PEER_RX_BUSY;
211 nr_stop_t4timer(sk);
212 }
213 if (nr_validate_nr(sk, nr)) {
214 if (frametype & NR_NAK_FLAG) {
215 nr_frames_acked(sk, nr);
216 nr_send_nak_frame(sk);
217 } else {
218 if (nrom->condition & NR_COND_PEER_RX_BUSY) {
219 nr_frames_acked(sk, nr);
220 } else {
221 nr_check_iframes_acked(sk, nr);
222 }
223 }
224 }
225 queued = 1;
226 skb_queue_head(&nrom->reseq_queue, skb);
227 if (nrom->condition & NR_COND_OWN_RX_BUSY)
228 break;
229 skb_queue_head_init(&temp_queue);
230 do {
231 save_vr = nrom->vr;
232 while ((skbn = skb_dequeue(&nrom->reseq_queue)) != NULL) {
233 ns = skbn->data[17];
234 if (ns == nrom->vr) {
235 if (nr_queue_rx_frame(sk, skbn, frametype & NR_MORE_FLAG) == 0) {
236 nrom->vr = (nrom->vr + 1) % NR_MODULUS;
237 } else {
238 nrom->condition |= NR_COND_OWN_RX_BUSY;
239 skb_queue_tail(&temp_queue, skbn);
240 }
241 } else if (nr_in_rx_window(sk, ns)) {
242 skb_queue_tail(&temp_queue, skbn);
243 } else {
244 kfree_skb(skbn);
245 }
246 }
247 while ((skbn = skb_dequeue(&temp_queue)) != NULL) {
248 skb_queue_tail(&nrom->reseq_queue, skbn);
249 }
250 } while (save_vr != nrom->vr);
251 /*
252 * Window is full, ack it immediately.
253 */
254 if (((nrom->vl + nrom->window) % NR_MODULUS) == nrom->vr) {
255 nr_enquiry_response(sk);
256 } else {
257 if (!(nrom->condition & NR_COND_ACK_PENDING)) {
258 nrom->condition |= NR_COND_ACK_PENDING;
259 nr_start_t2timer(sk);
260 }
261 }
262 break;
263
264 case NR_RESET:
265 if (READ_ONCE(sysctl_netrom_reset_circuit))
266 nr_disconnect(sk, ECONNRESET);
267 break;
268
269 default:
270 break;
271 }
272 return queued;
273 }
274
275 /* Higher level upcall for a LAPB frame - called with sk locked */
276 int nr_process_rx_frame(struct sock *sk, struct sk_buff *skb)
277 {
278 struct nr_sock *nr = nr_sk(sk);
279 int queued = 0, frametype;
280
281 if (nr->state == NR_STATE_0)
282 return 0;
283
284 frametype = skb->data[19];
285
286 switch (nr->state) {
287 case NR_STATE_1:
288 queued = nr_state1_machine(sk, skb, frametype);
289 break;
290 case NR_STATE_2:
291 queued = nr_state2_machine(sk, skb, frametype);
292 break;
293 case NR_STATE_3:
294 queued = nr_state3_machine(sk, skb, frametype);
295 break;
296 }
297
298 nr_kick(sk);
299
300 return queued;
301 }
302
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