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_CALL_REQUEST: 146 /* call collision */ 147 x25->causediag.cause = 0x01; 148 x25->causediag.diagnostic = 0x48; 149 150 x25_write_internal(sk, X25_CLEAR_REQUEST); 151 x25_disconnect(sk, EISCONN, 0x01, 0x48); 152 break; 153 154 case X25_CLEAR_REQUEST: 155 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) 156 goto out_clear; 157 158 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 159 x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]); 160 break; 161 162 default: 163 break; 164 } 165 166 return 0; 167 168 out_clear: 169 x25_write_internal(sk, X25_CLEAR_REQUEST); 170 x25->state = X25_STATE_2; 171 x25_start_t23timer(sk); 172 return 0; 173 } 174 175 /* 176 * State machine for state 2, Awaiting Clear Confirmation State. 177 * The handling of the timer(s) is in file x25_timer.c 178 * Handling of state 0 and connection release is in af_x25.c. 179 */ 180 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype) 181 { 182 switch (frametype) { 183 184 case X25_CLEAR_REQUEST: 185 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) 186 goto out_clear; 187 188 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 189 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 190 break; 191 192 case X25_CLEAR_CONFIRMATION: 193 x25_disconnect(sk, 0, 0, 0); 194 break; 195 196 default: 197 break; 198 } 199 200 return 0; 201 202 out_clear: 203 x25_write_internal(sk, X25_CLEAR_REQUEST); 204 x25_start_t23timer(sk); 205 return 0; 206 } 207 208 /* 209 * State machine for state 3, Connected State. 210 * The handling of the timer(s) is in file x25_timer.c 211 * Handling of state 0 and connection release is in af_x25.c. 212 */ 213 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m) 214 { 215 int queued = 0; 216 int modulus; 217 struct x25_sock *x25 = x25_sk(sk); 218 219 modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS; 220 221 switch (frametype) { 222 223 case X25_RESET_REQUEST: 224 x25_write_internal(sk, X25_RESET_CONFIRMATION); 225 x25_stop_timer(sk); 226 x25->condition = 0x00; 227 x25->vs = 0; 228 x25->vr = 0; 229 x25->va = 0; 230 x25->vl = 0; 231 x25_requeue_frames(sk); 232 break; 233 234 case X25_CLEAR_REQUEST: 235 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) 236 goto out_clear; 237 238 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 239 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 240 break; 241 242 case X25_RR: 243 case X25_RNR: 244 if (!x25_validate_nr(sk, nr)) { 245 x25_clear_queues(sk); 246 x25_write_internal(sk, X25_RESET_REQUEST); 247 x25_start_t22timer(sk); 248 x25->condition = 0x00; 249 x25->vs = 0; 250 x25->vr = 0; 251 x25->va = 0; 252 x25->vl = 0; 253 x25->state = X25_STATE_4; 254 } else { 255 x25_frames_acked(sk, nr); 256 if (frametype == X25_RNR) { 257 x25->condition |= X25_COND_PEER_RX_BUSY; 258 } else { 259 x25->condition &= ~X25_COND_PEER_RX_BUSY; 260 } 261 } 262 break; 263 264 case X25_DATA: /* XXX */ 265 x25->condition &= ~X25_COND_PEER_RX_BUSY; 266 if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) { 267 x25_clear_queues(sk); 268 x25_write_internal(sk, X25_RESET_REQUEST); 269 x25_start_t22timer(sk); 270 x25->condition = 0x00; 271 x25->vs = 0; 272 x25->vr = 0; 273 x25->va = 0; 274 x25->vl = 0; 275 x25->state = X25_STATE_4; 276 break; 277 } 278 x25_frames_acked(sk, nr); 279 if (ns == x25->vr) { 280 if (x25_queue_rx_frame(sk, skb, m) == 0) { 281 x25->vr = (x25->vr + 1) % modulus; 282 queued = 1; 283 } else { 284 /* Should never happen */ 285 x25_clear_queues(sk); 286 x25_write_internal(sk, X25_RESET_REQUEST); 287 x25_start_t22timer(sk); 288 x25->condition = 0x00; 289 x25->vs = 0; 290 x25->vr = 0; 291 x25->va = 0; 292 x25->vl = 0; 293 x25->state = X25_STATE_4; 294 break; 295 } 296 if (atomic_read(&sk->sk_rmem_alloc) > 297 (sk->sk_rcvbuf >> 1)) 298 x25->condition |= X25_COND_OWN_RX_BUSY; 299 } 300 /* 301 * If the window is full Ack it immediately, else 302 * start the holdback timer. 303 */ 304 if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) { 305 x25->condition &= ~X25_COND_ACK_PENDING; 306 x25_stop_timer(sk); 307 x25_enquiry_response(sk); 308 } else { 309 x25->condition |= X25_COND_ACK_PENDING; 310 x25_start_t2timer(sk); 311 } 312 break; 313 314 case X25_INTERRUPT_CONFIRMATION: 315 clear_bit(X25_INTERRUPT_FLAG, &x25->flags); 316 break; 317 318 case X25_INTERRUPT: 319 if (sock_flag(sk, SOCK_URGINLINE)) 320 queued = !sock_queue_rcv_skb(sk, skb); 321 else { 322 skb_set_owner_r(skb, sk); 323 skb_queue_tail(&x25->interrupt_in_queue, skb); 324 queued = 1; 325 } 326 sk_send_sigurg(sk); 327 x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION); 328 break; 329 330 default: 331 pr_warn("unknown %02X in state 3\n", frametype); 332 break; 333 } 334 335 return queued; 336 337 out_clear: 338 x25_write_internal(sk, X25_CLEAR_REQUEST); 339 x25->state = X25_STATE_2; 340 x25_start_t23timer(sk); 341 return 0; 342 } 343 344 /* 345 * State machine for state 4, Awaiting Reset Confirmation State. 346 * The handling of the timer(s) is in file x25_timer.c 347 * Handling of state 0 and connection release is in af_x25.c. 348 */ 349 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype) 350 { 351 struct x25_sock *x25 = x25_sk(sk); 352 353 switch (frametype) { 354 355 case X25_RESET_REQUEST: 356 x25_write_internal(sk, X25_RESET_CONFIRMATION); 357 /* fall through */ 358 case X25_RESET_CONFIRMATION: { 359 x25_stop_timer(sk); 360 x25->condition = 0x00; 361 x25->va = 0; 362 x25->vr = 0; 363 x25->vs = 0; 364 x25->vl = 0; 365 x25->state = X25_STATE_3; 366 x25_requeue_frames(sk); 367 break; 368 } 369 case X25_CLEAR_REQUEST: 370 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) 371 goto out_clear; 372 373 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 374 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 375 break; 376 377 default: 378 break; 379 } 380 381 return 0; 382 383 out_clear: 384 x25_write_internal(sk, X25_CLEAR_REQUEST); 385 x25->state = X25_STATE_2; 386 x25_start_t23timer(sk); 387 return 0; 388 } 389 390 /* Higher level upcall for a LAPB frame */ 391 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb) 392 { 393 struct x25_sock *x25 = x25_sk(sk); 394 int queued = 0, frametype, ns, nr, q, d, m; 395 396 if (x25->state == X25_STATE_0) 397 return 0; 398 399 frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m); 400 401 switch (x25->state) { 402 case X25_STATE_1: 403 queued = x25_state1_machine(sk, skb, frametype); 404 break; 405 case X25_STATE_2: 406 queued = x25_state2_machine(sk, skb, frametype); 407 break; 408 case X25_STATE_3: 409 queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m); 410 break; 411 case X25_STATE_4: 412 queued = x25_state4_machine(sk, skb, frametype); 413 break; 414 } 415 416 x25_kick(sk); 417 418 return queued; 419 } 420 421 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb) 422 { 423 int queued = x25_process_rx_frame(sk, skb); 424 425 if (!queued) 426 kfree_skb(skb); 427 428 return 0; 429 } 430