1 /* 2 * X.25 Packet Layer release 002 3 * 4 * This is ALPHA test software. This code may break your machine, 5 * randomly fail to work with new releases, misbehave and/or generally 6 * screw up. It might even work. 7 * 8 * This code REQUIRES 2.1.15 or higher 9 * 10 * This module: 11 * This module is free software; you can redistribute it and/or 12 * modify it under the terms of the GNU General Public License 13 * as published by the Free Software Foundation; either version 14 * 2 of the License, or (at your option) any later version. 15 * 16 * History 17 * X.25 001 Jonathan Naylor Started coding. 18 * X.25 002 Jonathan Naylor Centralised disconnection code. 19 * New timer architecture. 20 * 2000-03-20 Daniela Squassoni Disabling/enabling of facilities 21 * negotiation. 22 * 2000-11-10 Henner Eisen Check and reset for out-of-sequence 23 * i-frames. 24 */ 25 26 #define pr_fmt(fmt) "X25: " fmt 27 28 #include <linux/slab.h> 29 #include <linux/errno.h> 30 #include <linux/kernel.h> 31 #include <linux/string.h> 32 #include <linux/skbuff.h> 33 #include <net/sock.h> 34 #include <net/tcp_states.h> 35 #include <net/x25.h> 36 37 static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more) 38 { 39 struct sk_buff *skbo, *skbn = skb; 40 struct x25_sock *x25 = x25_sk(sk); 41 42 if (more) { 43 x25->fraglen += skb->len; 44 skb_queue_tail(&x25->fragment_queue, skb); 45 skb_set_owner_r(skb, sk); 46 return 0; 47 } 48 49 if (!more && x25->fraglen > 0) { /* End of fragment */ 50 int len = x25->fraglen + skb->len; 51 52 if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){ 53 kfree_skb(skb); 54 return 1; 55 } 56 57 skb_queue_tail(&x25->fragment_queue, skb); 58 59 skb_reset_transport_header(skbn); 60 61 skbo = skb_dequeue(&x25->fragment_queue); 62 skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len), 63 skbo->len); 64 kfree_skb(skbo); 65 66 while ((skbo = 67 skb_dequeue(&x25->fragment_queue)) != NULL) { 68 skb_pull(skbo, (x25->neighbour->extended) ? 69 X25_EXT_MIN_LEN : X25_STD_MIN_LEN); 70 skb_copy_from_linear_data(skbo, 71 skb_put(skbn, skbo->len), 72 skbo->len); 73 kfree_skb(skbo); 74 } 75 76 x25->fraglen = 0; 77 } 78 79 skb_set_owner_r(skbn, sk); 80 skb_queue_tail(&sk->sk_receive_queue, skbn); 81 if (!sock_flag(sk, SOCK_DEAD)) 82 sk->sk_data_ready(sk); 83 84 return 0; 85 } 86 87 /* 88 * State machine for state 1, Awaiting Call Accepted State. 89 * The handling of the timer(s) is in file x25_timer.c. 90 * Handling of state 0 and connection release is in af_x25.c. 91 */ 92 static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype) 93 { 94 struct x25_address source_addr, dest_addr; 95 int len; 96 struct x25_sock *x25 = x25_sk(sk); 97 98 switch (frametype) { 99 case X25_CALL_ACCEPTED: { 100 101 x25_stop_timer(sk); 102 x25->condition = 0x00; 103 x25->vs = 0; 104 x25->va = 0; 105 x25->vr = 0; 106 x25->vl = 0; 107 x25->state = X25_STATE_3; 108 sk->sk_state = TCP_ESTABLISHED; 109 /* 110 * Parse the data in the frame. 111 */ 112 if (!pskb_may_pull(skb, X25_STD_MIN_LEN)) 113 goto out_clear; 114 skb_pull(skb, X25_STD_MIN_LEN); 115 116 len = x25_parse_address_block(skb, &source_addr, 117 &dest_addr); 118 if (len > 0) 119 skb_pull(skb, len); 120 else if (len < 0) 121 goto out_clear; 122 123 len = x25_parse_facilities(skb, &x25->facilities, 124 &x25->dte_facilities, 125 &x25->vc_facil_mask); 126 if (len > 0) 127 skb_pull(skb, len); 128 else if (len < 0) 129 goto out_clear; 130 /* 131 * Copy any Call User Data. 132 */ 133 if (skb->len > 0) { 134 if (skb->len > X25_MAX_CUD_LEN) 135 goto out_clear; 136 137 skb_copy_bits(skb, 0, x25->calluserdata.cuddata, 138 skb->len); 139 x25->calluserdata.cudlength = skb->len; 140 } 141 if (!sock_flag(sk, SOCK_DEAD)) 142 sk->sk_state_change(sk); 143 break; 144 } 145 case X25_CLEAR_REQUEST: 146 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) 147 goto out_clear; 148 149 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 150 x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]); 151 break; 152 153 default: 154 break; 155 } 156 157 return 0; 158 159 out_clear: 160 x25_write_internal(sk, X25_CLEAR_REQUEST); 161 x25->state = X25_STATE_2; 162 x25_start_t23timer(sk); 163 return 0; 164 } 165 166 /* 167 * State machine for state 2, Awaiting Clear Confirmation State. 168 * The handling of the timer(s) is in file x25_timer.c 169 * Handling of state 0 and connection release is in af_x25.c. 170 */ 171 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype) 172 { 173 switch (frametype) { 174 175 case X25_CLEAR_REQUEST: 176 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) 177 goto out_clear; 178 179 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 180 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 181 break; 182 183 case X25_CLEAR_CONFIRMATION: 184 x25_disconnect(sk, 0, 0, 0); 185 break; 186 187 default: 188 break; 189 } 190 191 return 0; 192 193 out_clear: 194 x25_write_internal(sk, X25_CLEAR_REQUEST); 195 x25_start_t23timer(sk); 196 return 0; 197 } 198 199 /* 200 * State machine for state 3, Connected State. 201 * The handling of the timer(s) is in file x25_timer.c 202 * Handling of state 0 and connection release is in af_x25.c. 203 */ 204 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m) 205 { 206 int queued = 0; 207 int modulus; 208 struct x25_sock *x25 = x25_sk(sk); 209 210 modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS; 211 212 switch (frametype) { 213 214 case X25_RESET_REQUEST: 215 x25_write_internal(sk, X25_RESET_CONFIRMATION); 216 x25_stop_timer(sk); 217 x25->condition = 0x00; 218 x25->vs = 0; 219 x25->vr = 0; 220 x25->va = 0; 221 x25->vl = 0; 222 x25_requeue_frames(sk); 223 break; 224 225 case X25_CLEAR_REQUEST: 226 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) 227 goto out_clear; 228 229 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 230 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 231 break; 232 233 case X25_RR: 234 case X25_RNR: 235 if (!x25_validate_nr(sk, nr)) { 236 x25_clear_queues(sk); 237 x25_write_internal(sk, X25_RESET_REQUEST); 238 x25_start_t22timer(sk); 239 x25->condition = 0x00; 240 x25->vs = 0; 241 x25->vr = 0; 242 x25->va = 0; 243 x25->vl = 0; 244 x25->state = X25_STATE_4; 245 } else { 246 x25_frames_acked(sk, nr); 247 if (frametype == X25_RNR) { 248 x25->condition |= X25_COND_PEER_RX_BUSY; 249 } else { 250 x25->condition &= ~X25_COND_PEER_RX_BUSY; 251 } 252 } 253 break; 254 255 case X25_DATA: /* XXX */ 256 x25->condition &= ~X25_COND_PEER_RX_BUSY; 257 if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) { 258 x25_clear_queues(sk); 259 x25_write_internal(sk, X25_RESET_REQUEST); 260 x25_start_t22timer(sk); 261 x25->condition = 0x00; 262 x25->vs = 0; 263 x25->vr = 0; 264 x25->va = 0; 265 x25->vl = 0; 266 x25->state = X25_STATE_4; 267 break; 268 } 269 x25_frames_acked(sk, nr); 270 if (ns == x25->vr) { 271 if (x25_queue_rx_frame(sk, skb, m) == 0) { 272 x25->vr = (x25->vr + 1) % modulus; 273 queued = 1; 274 } else { 275 /* Should never happen */ 276 x25_clear_queues(sk); 277 x25_write_internal(sk, X25_RESET_REQUEST); 278 x25_start_t22timer(sk); 279 x25->condition = 0x00; 280 x25->vs = 0; 281 x25->vr = 0; 282 x25->va = 0; 283 x25->vl = 0; 284 x25->state = X25_STATE_4; 285 break; 286 } 287 if (atomic_read(&sk->sk_rmem_alloc) > 288 (sk->sk_rcvbuf >> 1)) 289 x25->condition |= X25_COND_OWN_RX_BUSY; 290 } 291 /* 292 * If the window is full Ack it immediately, else 293 * start the holdback timer. 294 */ 295 if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) { 296 x25->condition &= ~X25_COND_ACK_PENDING; 297 x25_stop_timer(sk); 298 x25_enquiry_response(sk); 299 } else { 300 x25->condition |= X25_COND_ACK_PENDING; 301 x25_start_t2timer(sk); 302 } 303 break; 304 305 case X25_INTERRUPT_CONFIRMATION: 306 clear_bit(X25_INTERRUPT_FLAG, &x25->flags); 307 break; 308 309 case X25_INTERRUPT: 310 if (sock_flag(sk, SOCK_URGINLINE)) 311 queued = !sock_queue_rcv_skb(sk, skb); 312 else { 313 skb_set_owner_r(skb, sk); 314 skb_queue_tail(&x25->interrupt_in_queue, skb); 315 queued = 1; 316 } 317 sk_send_sigurg(sk); 318 x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION); 319 break; 320 321 default: 322 pr_warn("unknown %02X in state 3\n", frametype); 323 break; 324 } 325 326 return queued; 327 328 out_clear: 329 x25_write_internal(sk, X25_CLEAR_REQUEST); 330 x25->state = X25_STATE_2; 331 x25_start_t23timer(sk); 332 return 0; 333 } 334 335 /* 336 * State machine for state 4, Awaiting Reset Confirmation State. 337 * The handling of the timer(s) is in file x25_timer.c 338 * Handling of state 0 and connection release is in af_x25.c. 339 */ 340 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype) 341 { 342 struct x25_sock *x25 = x25_sk(sk); 343 344 switch (frametype) { 345 346 case X25_RESET_REQUEST: 347 x25_write_internal(sk, X25_RESET_CONFIRMATION); 348 case X25_RESET_CONFIRMATION: { 349 x25_stop_timer(sk); 350 x25->condition = 0x00; 351 x25->va = 0; 352 x25->vr = 0; 353 x25->vs = 0; 354 x25->vl = 0; 355 x25->state = X25_STATE_3; 356 x25_requeue_frames(sk); 357 break; 358 } 359 case X25_CLEAR_REQUEST: 360 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) 361 goto out_clear; 362 363 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 364 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 365 break; 366 367 default: 368 break; 369 } 370 371 return 0; 372 373 out_clear: 374 x25_write_internal(sk, X25_CLEAR_REQUEST); 375 x25->state = X25_STATE_2; 376 x25_start_t23timer(sk); 377 return 0; 378 } 379 380 /* Higher level upcall for a LAPB frame */ 381 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb) 382 { 383 struct x25_sock *x25 = x25_sk(sk); 384 int queued = 0, frametype, ns, nr, q, d, m; 385 386 if (x25->state == X25_STATE_0) 387 return 0; 388 389 frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m); 390 391 switch (x25->state) { 392 case X25_STATE_1: 393 queued = x25_state1_machine(sk, skb, frametype); 394 break; 395 case X25_STATE_2: 396 queued = x25_state2_machine(sk, skb, frametype); 397 break; 398 case X25_STATE_3: 399 queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m); 400 break; 401 case X25_STATE_4: 402 queued = x25_state4_machine(sk, skb, frametype); 403 break; 404 } 405 406 x25_kick(sk); 407 408 return queued; 409 } 410 411 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb) 412 { 413 int queued = x25_process_rx_frame(sk, skb); 414 415 if (!queued) 416 kfree_skb(skb); 417 418 return 0; 419 } 420