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 29static 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 */ 71static 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 (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 */ 115static 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 (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 */ 146static 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 ns = skb->data[17]; 157 158 switch (frametype) { 159 case NR_CONNREQ: 160 nr_write_internal(sk, NR_CONNACK); 161 break; 162 163 case NR_DISCREQ: 164 nr_write_internal(sk, NR_DISCACK); 165 nr_disconnect(sk, 0); 166 break; 167 168 case NR_CONNACK | NR_CHOKE_FLAG: 169 case NR_DISCACK: 170 nr_disconnect(sk, ECONNRESET); 171 break; 172 173 case NR_INFOACK: 174 case NR_INFOACK | NR_CHOKE_FLAG: 175 case NR_INFOACK | NR_NAK_FLAG: 176 case NR_INFOACK | NR_NAK_FLAG | NR_CHOKE_FLAG: 177 if (frametype & NR_CHOKE_FLAG) { 178 nrom->condition |= NR_COND_PEER_RX_BUSY; 179 nr_start_t4timer(sk); 180 } else { 181 nrom->condition &= ~NR_COND_PEER_RX_BUSY; 182 nr_stop_t4timer(sk); 183 } 184 if (!nr_validate_nr(sk, nr)) { 185 break; 186 } 187 if (frametype & NR_NAK_FLAG) { 188 nr_frames_acked(sk, nr); 189 nr_send_nak_frame(sk); 190 } else { 191 if (nrom->condition & NR_COND_PEER_RX_BUSY) { 192 nr_frames_acked(sk, nr); 193 } else { 194 nr_check_iframes_acked(sk, nr); 195 } 196 } 197 break; 198 199 case NR_INFO: 200 case NR_INFO | NR_NAK_FLAG: 201 case NR_INFO | NR_CHOKE_FLAG: 202 case NR_INFO | NR_MORE_FLAG: 203 case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG: 204 case NR_INFO | NR_CHOKE_FLAG | NR_MORE_FLAG: 205 case NR_INFO | NR_NAK_FLAG | NR_MORE_FLAG: 206 case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG | NR_MORE_FLAG: 207 if (frametype & NR_CHOKE_FLAG) { 208 nrom->condition |= NR_COND_PEER_RX_BUSY; 209 nr_start_t4timer(sk); 210 } else { 211 nrom->condition &= ~NR_COND_PEER_RX_BUSY; 212 nr_stop_t4timer(sk); 213 } 214 if (nr_validate_nr(sk, nr)) { 215 if (frametype & NR_NAK_FLAG) { 216 nr_frames_acked(sk, nr); 217 nr_send_nak_frame(sk); 218 } else { 219 if (nrom->condition & NR_COND_PEER_RX_BUSY) { 220 nr_frames_acked(sk, nr); 221 } else { 222 nr_check_iframes_acked(sk, nr); 223 } 224 } 225 } 226 queued = 1; 227 skb_queue_head(&nrom->reseq_queue, skb); 228 if (nrom->condition & NR_COND_OWN_RX_BUSY) 229 break; 230 skb_queue_head_init(&temp_queue); 231 do { 232 save_vr = nrom->vr; 233 while ((skbn = skb_dequeue(&nrom->reseq_queue)) != NULL) { 234 ns = skbn->data[17]; 235 if (ns == nrom->vr) { 236 if (nr_queue_rx_frame(sk, skbn, frametype & NR_MORE_FLAG) == 0) { 237 nrom->vr = (nrom->vr + 1) % NR_MODULUS; 238 } else { 239 nrom->condition |= NR_COND_OWN_RX_BUSY; 240 skb_queue_tail(&temp_queue, skbn); 241 } 242 } else if (nr_in_rx_window(sk, ns)) { 243 skb_queue_tail(&temp_queue, skbn); 244 } else { 245 kfree_skb(skbn); 246 } 247 } 248 while ((skbn = skb_dequeue(&temp_queue)) != NULL) { 249 skb_queue_tail(&nrom->reseq_queue, skbn); 250 } 251 } while (save_vr != nrom->vr); 252 /* 253 * Window is full, ack it immediately. 254 */ 255 if (((nrom->vl + nrom->window) % NR_MODULUS) == nrom->vr) { 256 nr_enquiry_response(sk); 257 } else { 258 if (!(nrom->condition & NR_COND_ACK_PENDING)) { 259 nrom->condition |= NR_COND_ACK_PENDING; 260 nr_start_t2timer(sk); 261 } 262 } 263 break; 264 265 case NR_RESET: 266 if (sysctl_netrom_reset_circuit) 267 nr_disconnect(sk, ECONNRESET); 268 break; 269 270 default: 271 break; 272 } 273 return queued; 274} 275 276/* Higher level upcall for a LAPB frame - called with sk locked */ 277int nr_process_rx_frame(struct sock *sk, struct sk_buff *skb) 278{ 279 struct nr_sock *nr = nr_sk(sk); 280 int queued = 0, frametype; 281 282 if (nr->state == NR_STATE_0) 283 return 0; 284 285 frametype = skb->data[19]; 286 287 switch (nr->state) { 288 case NR_STATE_1: 289 queued = nr_state1_machine(sk, skb, frametype); 290 break; 291 case NR_STATE_2: 292 queued = nr_state2_machine(sk, skb, frametype); 293 break; 294 case NR_STATE_3: 295 queued = nr_state3_machine(sk, skb, frametype); 296 break; 297 } 298 299 nr_kick(sk); 300 301 return queued; 302} 303