1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * 4 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk) 5 * 6 * Most of this code is based on the SDL diagrams published in the 7th ARRL 7 * Computer Networking Conference papers. The diagrams have mistakes in them, 8 * but are mostly correct. Before you modify the code could you read the SDL 9 * diagrams as the code is not obvious and probably very easy to break. 10 */ 11 #include <linux/errno.h> 12 #include <linux/filter.h> 13 #include <linux/types.h> 14 #include <linux/socket.h> 15 #include <linux/in.h> 16 #include <linux/kernel.h> 17 #include <linux/timer.h> 18 #include <linux/string.h> 19 #include <linux/sockios.h> 20 #include <linux/net.h> 21 #include <net/ax25.h> 22 #include <linux/inet.h> 23 #include <linux/netdevice.h> 24 #include <linux/skbuff.h> 25 #include <net/sock.h> 26 #include <net/tcp_states.h> 27 #include <linux/fcntl.h> 28 #include <linux/mm.h> 29 #include <linux/interrupt.h> 30 #include <net/rose.h> 31 32 /* 33 * State machine for state 1, Awaiting Call Accepted State. 34 * The handling of the timer(s) is in file rose_timer.c. 35 * Handling of state 0 and connection release is in af_rose.c. 36 */ 37 static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype) 38 { 39 struct rose_sock *rose = rose_sk(sk); 40 41 switch (frametype) { 42 case ROSE_CALL_ACCEPTED: 43 rose_stop_timer(sk); 44 rose_start_idletimer(sk); 45 rose->condition = 0x00; 46 rose->vs = 0; 47 rose->va = 0; 48 rose->vr = 0; 49 rose->vl = 0; 50 rose->state = ROSE_STATE_3; 51 sk->sk_state = TCP_ESTABLISHED; 52 if (!sock_flag(sk, SOCK_DEAD)) 53 sk->sk_state_change(sk); 54 break; 55 56 case ROSE_CLEAR_REQUEST: 57 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); 58 rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]); 59 rose_neigh_put(rose->neighbour); 60 break; 61 62 default: 63 break; 64 } 65 66 return 0; 67 } 68 69 /* 70 * State machine for state 2, Awaiting Clear Confirmation State. 71 * The handling of the timer(s) is in file rose_timer.c 72 * Handling of state 0 and connection release is in af_rose.c. 73 */ 74 static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype) 75 { 76 struct rose_sock *rose = rose_sk(sk); 77 78 switch (frametype) { 79 case ROSE_CLEAR_REQUEST: 80 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); 81 rose_disconnect(sk, 0, skb->data[3], skb->data[4]); 82 rose_neigh_put(rose->neighbour); 83 break; 84 85 case ROSE_CLEAR_CONFIRMATION: 86 rose_disconnect(sk, 0, -1, -1); 87 rose_neigh_put(rose->neighbour); 88 break; 89 90 default: 91 break; 92 } 93 94 return 0; 95 } 96 97 /* 98 * State machine for state 3, Connected State. 99 * The handling of the timer(s) is in file rose_timer.c 100 * Handling of state 0 and connection release is in af_rose.c. 101 */ 102 static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m) 103 { 104 enum skb_drop_reason dr; /* ignored */ 105 struct rose_sock *rose = rose_sk(sk); 106 int queued = 0; 107 108 switch (frametype) { 109 case ROSE_RESET_REQUEST: 110 rose_stop_timer(sk); 111 rose_start_idletimer(sk); 112 rose_write_internal(sk, ROSE_RESET_CONFIRMATION); 113 rose->condition = 0x00; 114 rose->vs = 0; 115 rose->vr = 0; 116 rose->va = 0; 117 rose->vl = 0; 118 rose_requeue_frames(sk); 119 break; 120 121 case ROSE_CLEAR_REQUEST: 122 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); 123 rose_disconnect(sk, 0, skb->data[3], skb->data[4]); 124 rose_neigh_put(rose->neighbour); 125 break; 126 127 case ROSE_RR: 128 case ROSE_RNR: 129 if (!rose_validate_nr(sk, nr)) { 130 rose_write_internal(sk, ROSE_RESET_REQUEST); 131 rose->condition = 0x00; 132 rose->vs = 0; 133 rose->vr = 0; 134 rose->va = 0; 135 rose->vl = 0; 136 rose->state = ROSE_STATE_4; 137 rose_start_t2timer(sk); 138 rose_stop_idletimer(sk); 139 } else { 140 rose_frames_acked(sk, nr); 141 if (frametype == ROSE_RNR) { 142 rose->condition |= ROSE_COND_PEER_RX_BUSY; 143 } else { 144 rose->condition &= ~ROSE_COND_PEER_RX_BUSY; 145 } 146 } 147 break; 148 149 case ROSE_DATA: /* XXX */ 150 rose->condition &= ~ROSE_COND_PEER_RX_BUSY; 151 if (!rose_validate_nr(sk, nr)) { 152 rose_write_internal(sk, ROSE_RESET_REQUEST); 153 rose->condition = 0x00; 154 rose->vs = 0; 155 rose->vr = 0; 156 rose->va = 0; 157 rose->vl = 0; 158 rose->state = ROSE_STATE_4; 159 rose_start_t2timer(sk); 160 rose_stop_idletimer(sk); 161 break; 162 } 163 rose_frames_acked(sk, nr); 164 if (ns == rose->vr) { 165 rose_start_idletimer(sk); 166 if (!sk_filter_trim_cap(sk, skb, ROSE_MIN_LEN, &dr) && 167 __sock_queue_rcv_skb(sk, skb) == 0) { 168 rose->vr = (rose->vr + 1) % ROSE_MODULUS; 169 queued = 1; 170 } else { 171 /* Should never happen ! */ 172 rose_write_internal(sk, ROSE_RESET_REQUEST); 173 rose->condition = 0x00; 174 rose->vs = 0; 175 rose->vr = 0; 176 rose->va = 0; 177 rose->vl = 0; 178 rose->state = ROSE_STATE_4; 179 rose_start_t2timer(sk); 180 rose_stop_idletimer(sk); 181 break; 182 } 183 if (atomic_read(&sk->sk_rmem_alloc) > 184 (sk->sk_rcvbuf >> 1)) 185 rose->condition |= ROSE_COND_OWN_RX_BUSY; 186 } 187 /* 188 * If the window is full, ack the frame, else start the 189 * acknowledge hold back timer. 190 */ 191 if (((rose->vl + sysctl_rose_window_size) % ROSE_MODULUS) == rose->vr) { 192 rose->condition &= ~ROSE_COND_ACK_PENDING; 193 rose_stop_timer(sk); 194 rose_enquiry_response(sk); 195 } else { 196 rose->condition |= ROSE_COND_ACK_PENDING; 197 rose_start_hbtimer(sk); 198 } 199 break; 200 201 default: 202 printk(KERN_WARNING "ROSE: unknown %02X in state 3\n", frametype); 203 break; 204 } 205 206 return queued; 207 } 208 209 /* 210 * State machine for state 4, Awaiting Reset Confirmation State. 211 * The handling of the timer(s) is in file rose_timer.c 212 * Handling of state 0 and connection release is in af_rose.c. 213 */ 214 static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype) 215 { 216 struct rose_sock *rose = rose_sk(sk); 217 218 switch (frametype) { 219 case ROSE_RESET_REQUEST: 220 rose_write_internal(sk, ROSE_RESET_CONFIRMATION); 221 fallthrough; 222 case ROSE_RESET_CONFIRMATION: 223 rose_stop_timer(sk); 224 rose_start_idletimer(sk); 225 rose->condition = 0x00; 226 rose->va = 0; 227 rose->vr = 0; 228 rose->vs = 0; 229 rose->vl = 0; 230 rose->state = ROSE_STATE_3; 231 rose_requeue_frames(sk); 232 break; 233 234 case ROSE_CLEAR_REQUEST: 235 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); 236 rose_disconnect(sk, 0, skb->data[3], skb->data[4]); 237 rose_neigh_put(rose->neighbour); 238 break; 239 240 default: 241 break; 242 } 243 244 return 0; 245 } 246 247 /* 248 * State machine for state 5, Awaiting Call Acceptance State. 249 * The handling of the timer(s) is in file rose_timer.c 250 * Handling of state 0 and connection release is in af_rose.c. 251 */ 252 static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype) 253 { 254 if (frametype == ROSE_CLEAR_REQUEST) { 255 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); 256 rose_disconnect(sk, 0, skb->data[3], skb->data[4]); 257 rose_neigh_put(rose_sk(sk)->neighbour); 258 } 259 260 return 0; 261 } 262 263 /* Higher level upcall for a LAPB frame */ 264 int rose_process_rx_frame(struct sock *sk, struct sk_buff *skb) 265 { 266 struct rose_sock *rose = rose_sk(sk); 267 int queued = 0, frametype, ns, nr, q, d, m; 268 269 if (rose->state == ROSE_STATE_0) 270 return 0; 271 272 frametype = rose_decode(skb, &ns, &nr, &q, &d, &m); 273 274 switch (rose->state) { 275 case ROSE_STATE_1: 276 queued = rose_state1_machine(sk, skb, frametype); 277 break; 278 case ROSE_STATE_2: 279 queued = rose_state2_machine(sk, skb, frametype); 280 break; 281 case ROSE_STATE_3: 282 queued = rose_state3_machine(sk, skb, frametype, ns, nr, q, d, m); 283 break; 284 case ROSE_STATE_4: 285 queued = rose_state4_machine(sk, skb, frametype); 286 break; 287 case ROSE_STATE_5: 288 queued = rose_state5_machine(sk, skb, frametype); 289 break; 290 } 291 292 rose_kick(sk); 293 294 return queued; 295 } 296