| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
| 2 | /* |
| 3 | * X.25 Packet Layer release 002 |
| 4 | * |
| 5 | * This is ALPHA test software. This code may break your machine, |
| 6 | * randomly fail to work with new releases, misbehave and/or generally |
| 7 | * screw up. It might even work. |
| 8 | * |
| 9 | * This code REQUIRES 2.1.15 or higher |
| 10 | * |
| 11 | * History |
| 12 | * X.25 001 Jonathan Naylor Started coding. |
| 13 | * X.25 002 Jonathan Naylor Centralised disconnection code. |
| 14 | * New timer architecture. |
| 15 | * 2000-03-20 Daniela Squassoni Disabling/enabling of facilities |
| 16 | * negotiation. |
| 17 | * 2000-11-10 Henner Eisen Check and reset for out-of-sequence |
| 18 | * i-frames. |
| 19 | */ |
| 20 | |
| 21 | #define pr_fmt(fmt) "X25: " fmt |
| 22 | |
| 23 | #include <linux/slab.h> |
| 24 | #include <linux/errno.h> |
| 25 | #include <linux/kernel.h> |
| 26 | #include <linux/string.h> |
| 27 | #include <linux/skbuff.h> |
| 28 | #include <net/sock.h> |
| 29 | #include <net/tcp_states.h> |
| 30 | #include <net/x25.h> |
| 31 | |
| 32 | static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more) |
| 33 | { |
| 34 | struct sk_buff *skbo, *skbn = skb; |
| 35 | struct x25_sock *x25 = x25_sk(sk); |
| 36 | |
| 37 | if (more) { |
| 38 | x25->fraglen += skb->len; |
| 39 | skb_queue_tail(&x25->fragment_queue, skb); |
| 40 | skb_set_owner_r(skb, sk); |
| 41 | return 0; |
| 42 | } |
| 43 | |
| 44 | if (x25->fraglen > 0) { /* End of fragment */ |
| 45 | int len = x25->fraglen + skb->len; |
| 46 | |
| 47 | if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){ |
| 48 | kfree_skb(skb); |
| 49 | return 1; |
| 50 | } |
| 51 | |
| 52 | skb_queue_tail(&x25->fragment_queue, skb); |
| 53 | |
| 54 | skb_reset_transport_header(skbn); |
| 55 | |
| 56 | skbo = skb_dequeue(&x25->fragment_queue); |
| 57 | skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len), |
| 58 | skbo->len); |
| 59 | kfree_skb(skbo); |
| 60 | |
| 61 | while ((skbo = |
| 62 | skb_dequeue(&x25->fragment_queue)) != NULL) { |
| 63 | skb_pull(skbo, (x25->neighbour->extended) ? |
| 64 | X25_EXT_MIN_LEN : X25_STD_MIN_LEN); |
| 65 | skb_copy_from_linear_data(skbo, |
| 66 | skb_put(skbn, skbo->len), |
| 67 | skbo->len); |
| 68 | kfree_skb(skbo); |
| 69 | } |
| 70 | |
| 71 | x25->fraglen = 0; |
| 72 | } |
| 73 | |
| 74 | skb_set_owner_r(skbn, sk); |
| 75 | skb_queue_tail(&sk->sk_receive_queue, skbn); |
| 76 | if (!sock_flag(sk, SOCK_DEAD)) |
| 77 | sk->sk_data_ready(sk); |
| 78 | |
| 79 | return 0; |
| 80 | } |
| 81 | |
| 82 | /* |
| 83 | * State machine for state 1, Awaiting Call Accepted State. |
| 84 | * The handling of the timer(s) is in file x25_timer.c. |
| 85 | * Handling of state 0 and connection release is in af_x25.c. |
| 86 | */ |
| 87 | static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype) |
| 88 | { |
| 89 | struct x25_address source_addr, dest_addr; |
| 90 | int len; |
| 91 | struct x25_sock *x25 = x25_sk(sk); |
| 92 | |
| 93 | switch (frametype) { |
| 94 | case X25_CALL_ACCEPTED: { |
| 95 | |
| 96 | x25_stop_timer(sk); |
| 97 | x25->condition = 0x00; |
| 98 | x25->vs = 0; |
| 99 | x25->va = 0; |
| 100 | x25->vr = 0; |
| 101 | x25->vl = 0; |
| 102 | x25->state = X25_STATE_3; |
| 103 | sk->sk_state = TCP_ESTABLISHED; |
| 104 | /* |
| 105 | * Parse the data in the frame. |
| 106 | */ |
| 107 | if (!pskb_may_pull(skb, X25_STD_MIN_LEN)) |
| 108 | goto out_clear; |
| 109 | skb_pull(skb, X25_STD_MIN_LEN); |
| 110 | |
| 111 | len = x25_parse_address_block(skb, &source_addr, |
| 112 | &dest_addr); |
| 113 | if (len > 0) |
| 114 | skb_pull(skb, len); |
| 115 | else if (len < 0) |
| 116 | goto out_clear; |
| 117 | |
| 118 | len = x25_parse_facilities(skb, &x25->facilities, |
| 119 | &x25->dte_facilities, |
| 120 | &x25->vc_facil_mask); |
| 121 | if (len > 0) |
| 122 | skb_pull(skb, len); |
| 123 | else if (len < 0) |
| 124 | goto out_clear; |
| 125 | /* |
| 126 | * Copy any Call User Data. |
| 127 | */ |
| 128 | if (skb->len > 0) { |
| 129 | if (skb->len > X25_MAX_CUD_LEN) |
| 130 | goto out_clear; |
| 131 | |
| 132 | skb_copy_bits(skb, 0, x25->calluserdata.cuddata, |
| 133 | skb->len); |
| 134 | x25->calluserdata.cudlength = skb->len; |
| 135 | } |
| 136 | if (!sock_flag(sk, SOCK_DEAD)) |
| 137 | sk->sk_state_change(sk); |
| 138 | break; |
| 139 | } |
| 140 | case X25_CALL_REQUEST: |
| 141 | /* call collision */ |
| 142 | x25->causediag.cause = 0x01; |
| 143 | x25->causediag.diagnostic = 0x48; |
| 144 | |
| 145 | x25_write_internal(sk, X25_CLEAR_REQUEST); |
| 146 | x25_disconnect(sk, EISCONN, 0x01, 0x48); |
| 147 | break; |
| 148 | |
| 149 | case X25_CLEAR_REQUEST: |
| 150 | if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) |
| 151 | goto out_clear; |
| 152 | |
| 153 | x25_write_internal(sk, X25_CLEAR_CONFIRMATION); |
| 154 | x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]); |
| 155 | break; |
| 156 | |
| 157 | default: |
| 158 | break; |
| 159 | } |
| 160 | |
| 161 | return 0; |
| 162 | |
| 163 | out_clear: |
| 164 | x25_write_internal(sk, X25_CLEAR_REQUEST); |
| 165 | x25->state = X25_STATE_2; |
| 166 | x25_start_t23timer(sk); |
| 167 | return 0; |
| 168 | } |
| 169 | |
| 170 | /* |
| 171 | * State machine for state 2, Awaiting Clear Confirmation State. |
| 172 | * The handling of the timer(s) is in file x25_timer.c |
| 173 | * Handling of state 0 and connection release is in af_x25.c. |
| 174 | */ |
| 175 | static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype) |
| 176 | { |
| 177 | switch (frametype) { |
| 178 | |
| 179 | case X25_CLEAR_REQUEST: |
| 180 | if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) |
| 181 | goto out_clear; |
| 182 | |
| 183 | x25_write_internal(sk, X25_CLEAR_CONFIRMATION); |
| 184 | x25_disconnect(sk, 0, skb->data[3], skb->data[4]); |
| 185 | break; |
| 186 | |
| 187 | case X25_CLEAR_CONFIRMATION: |
| 188 | x25_disconnect(sk, 0, 0, 0); |
| 189 | break; |
| 190 | |
| 191 | default: |
| 192 | break; |
| 193 | } |
| 194 | |
| 195 | return 0; |
| 196 | |
| 197 | out_clear: |
| 198 | x25_write_internal(sk, X25_CLEAR_REQUEST); |
| 199 | x25_start_t23timer(sk); |
| 200 | return 0; |
| 201 | } |
| 202 | |
| 203 | /* |
| 204 | * State machine for state 3, Connected State. |
| 205 | * The handling of the timer(s) is in file x25_timer.c |
| 206 | * Handling of state 0 and connection release is in af_x25.c. |
| 207 | */ |
| 208 | static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m) |
| 209 | { |
| 210 | int queued = 0; |
| 211 | int modulus; |
| 212 | struct x25_sock *x25 = x25_sk(sk); |
| 213 | |
| 214 | modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS; |
| 215 | |
| 216 | switch (frametype) { |
| 217 | |
| 218 | case X25_RESET_REQUEST: |
| 219 | x25_write_internal(sk, X25_RESET_CONFIRMATION); |
| 220 | x25_stop_timer(sk); |
| 221 | x25->condition = 0x00; |
| 222 | x25->vs = 0; |
| 223 | x25->vr = 0; |
| 224 | x25->va = 0; |
| 225 | x25->vl = 0; |
| 226 | x25_requeue_frames(sk); |
| 227 | break; |
| 228 | |
| 229 | case X25_CLEAR_REQUEST: |
| 230 | if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) |
| 231 | goto out_clear; |
| 232 | |
| 233 | x25_write_internal(sk, X25_CLEAR_CONFIRMATION); |
| 234 | x25_disconnect(sk, 0, skb->data[3], skb->data[4]); |
| 235 | break; |
| 236 | |
| 237 | case X25_RR: |
| 238 | case X25_RNR: |
| 239 | if (!x25_validate_nr(sk, nr)) { |
| 240 | x25_clear_queues(sk); |
| 241 | x25_write_internal(sk, X25_RESET_REQUEST); |
| 242 | x25_start_t22timer(sk); |
| 243 | x25->condition = 0x00; |
| 244 | x25->vs = 0; |
| 245 | x25->vr = 0; |
| 246 | x25->va = 0; |
| 247 | x25->vl = 0; |
| 248 | x25->state = X25_STATE_4; |
| 249 | } else { |
| 250 | x25_frames_acked(sk, nr); |
| 251 | if (frametype == X25_RNR) { |
| 252 | x25->condition |= X25_COND_PEER_RX_BUSY; |
| 253 | } else { |
| 254 | x25->condition &= ~X25_COND_PEER_RX_BUSY; |
| 255 | } |
| 256 | } |
| 257 | break; |
| 258 | |
| 259 | case X25_DATA: /* XXX */ |
| 260 | x25->condition &= ~X25_COND_PEER_RX_BUSY; |
| 261 | if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) { |
| 262 | x25_clear_queues(sk); |
| 263 | x25_write_internal(sk, X25_RESET_REQUEST); |
| 264 | x25_start_t22timer(sk); |
| 265 | x25->condition = 0x00; |
| 266 | x25->vs = 0; |
| 267 | x25->vr = 0; |
| 268 | x25->va = 0; |
| 269 | x25->vl = 0; |
| 270 | x25->state = X25_STATE_4; |
| 271 | break; |
| 272 | } |
| 273 | x25_frames_acked(sk, nr); |
| 274 | if (ns == x25->vr) { |
| 275 | if (x25_queue_rx_frame(sk, skb, m) == 0) { |
| 276 | x25->vr = (x25->vr + 1) % modulus; |
| 277 | queued = 1; |
| 278 | } else { |
| 279 | /* Should never happen */ |
| 280 | x25_clear_queues(sk); |
| 281 | x25_write_internal(sk, X25_RESET_REQUEST); |
| 282 | x25_start_t22timer(sk); |
| 283 | x25->condition = 0x00; |
| 284 | x25->vs = 0; |
| 285 | x25->vr = 0; |
| 286 | x25->va = 0; |
| 287 | x25->vl = 0; |
| 288 | x25->state = X25_STATE_4; |
| 289 | break; |
| 290 | } |
| 291 | if (atomic_read(&sk->sk_rmem_alloc) > |
| 292 | (sk->sk_rcvbuf >> 1)) |
| 293 | x25->condition |= X25_COND_OWN_RX_BUSY; |
| 294 | } |
| 295 | /* |
| 296 | * If the window is full Ack it immediately, else |
| 297 | * start the holdback timer. |
| 298 | */ |
| 299 | if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) { |
| 300 | x25->condition &= ~X25_COND_ACK_PENDING; |
| 301 | x25_stop_timer(sk); |
| 302 | x25_enquiry_response(sk); |
| 303 | } else { |
| 304 | x25->condition |= X25_COND_ACK_PENDING; |
| 305 | x25_start_t2timer(sk); |
| 306 | } |
| 307 | break; |
| 308 | |
| 309 | case X25_INTERRUPT_CONFIRMATION: |
| 310 | clear_bit(X25_INTERRUPT_FLAG, &x25->flags); |
| 311 | break; |
| 312 | |
| 313 | case X25_INTERRUPT: |
| 314 | if (sock_flag(sk, SOCK_URGINLINE)) |
| 315 | queued = !sock_queue_rcv_skb(sk, skb); |
| 316 | else { |
| 317 | skb_set_owner_r(skb, sk); |
| 318 | skb_queue_tail(&x25->interrupt_in_queue, skb); |
| 319 | queued = 1; |
| 320 | } |
| 321 | sk_send_sigurg(sk); |
| 322 | x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION); |
| 323 | break; |
| 324 | |
| 325 | default: |
| 326 | pr_warn("unknown %02X in state 3\n", frametype); |
| 327 | break; |
| 328 | } |
| 329 | |
| 330 | return queued; |
| 331 | |
| 332 | out_clear: |
| 333 | x25_write_internal(sk, X25_CLEAR_REQUEST); |
| 334 | x25->state = X25_STATE_2; |
| 335 | x25_start_t23timer(sk); |
| 336 | return 0; |
| 337 | } |
| 338 | |
| 339 | /* |
| 340 | * State machine for state 4, Awaiting Reset Confirmation State. |
| 341 | * The handling of the timer(s) is in file x25_timer.c |
| 342 | * Handling of state 0 and connection release is in af_x25.c. |
| 343 | */ |
| 344 | static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype) |
| 345 | { |
| 346 | struct x25_sock *x25 = x25_sk(sk); |
| 347 | |
| 348 | switch (frametype) { |
| 349 | |
| 350 | case X25_RESET_REQUEST: |
| 351 | x25_write_internal(sk, X25_RESET_CONFIRMATION); |
| 352 | fallthrough; |
| 353 | case X25_RESET_CONFIRMATION: { |
| 354 | x25_stop_timer(sk); |
| 355 | x25->condition = 0x00; |
| 356 | x25->va = 0; |
| 357 | x25->vr = 0; |
| 358 | x25->vs = 0; |
| 359 | x25->vl = 0; |
| 360 | x25->state = X25_STATE_3; |
| 361 | x25_requeue_frames(sk); |
| 362 | break; |
| 363 | } |
| 364 | case X25_CLEAR_REQUEST: |
| 365 | if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) |
| 366 | goto out_clear; |
| 367 | |
| 368 | x25_write_internal(sk, X25_CLEAR_CONFIRMATION); |
| 369 | x25_disconnect(sk, 0, skb->data[3], skb->data[4]); |
| 370 | break; |
| 371 | |
| 372 | default: |
| 373 | break; |
| 374 | } |
| 375 | |
| 376 | return 0; |
| 377 | |
| 378 | out_clear: |
| 379 | x25_write_internal(sk, X25_CLEAR_REQUEST); |
| 380 | x25->state = X25_STATE_2; |
| 381 | x25_start_t23timer(sk); |
| 382 | return 0; |
| 383 | } |
| 384 | |
| 385 | /* |
| 386 | * State machine for state 5, Call Accepted / Call Connected pending (X25_ACCPT_APPRV_FLAG). |
| 387 | * The handling of the timer(s) is in file x25_timer.c |
| 388 | * Handling of state 0 and connection release is in af_x25.c. |
| 389 | */ |
| 390 | static int x25_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype) |
| 391 | { |
| 392 | struct x25_sock *x25 = x25_sk(sk); |
| 393 | |
| 394 | switch (frametype) { |
| 395 | case X25_CLEAR_REQUEST: |
| 396 | if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) { |
| 397 | x25_write_internal(sk, X25_CLEAR_REQUEST); |
| 398 | x25->state = X25_STATE_2; |
| 399 | x25_start_t23timer(sk); |
| 400 | return 0; |
| 401 | } |
| 402 | |
| 403 | x25_write_internal(sk, X25_CLEAR_CONFIRMATION); |
| 404 | x25_disconnect(sk, 0, skb->data[3], skb->data[4]); |
| 405 | break; |
| 406 | |
| 407 | default: |
| 408 | break; |
| 409 | } |
| 410 | |
| 411 | return 0; |
| 412 | } |
| 413 | |
| 414 | /* Higher level upcall for a LAPB frame */ |
| 415 | int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb) |
| 416 | { |
| 417 | struct x25_sock *x25 = x25_sk(sk); |
| 418 | int queued = 0, frametype, ns, nr, q, d, m; |
| 419 | |
| 420 | if (x25->state == X25_STATE_0) |
| 421 | return 0; |
| 422 | |
| 423 | frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m); |
| 424 | |
| 425 | switch (x25->state) { |
| 426 | case X25_STATE_1: |
| 427 | queued = x25_state1_machine(sk, skb, frametype); |
| 428 | break; |
| 429 | case X25_STATE_2: |
| 430 | queued = x25_state2_machine(sk, skb, frametype); |
| 431 | break; |
| 432 | case X25_STATE_3: |
| 433 | queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m); |
| 434 | break; |
| 435 | case X25_STATE_4: |
| 436 | queued = x25_state4_machine(sk, skb, frametype); |
| 437 | break; |
| 438 | case X25_STATE_5: |
| 439 | queued = x25_state5_machine(sk, skb, frametype); |
| 440 | break; |
| 441 | } |
| 442 | |
| 443 | x25_kick(sk); |
| 444 | |
| 445 | return queued; |
| 446 | } |
| 447 | |
| 448 | int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb) |
| 449 | { |
| 450 | int queued = x25_process_rx_frame(sk, skb); |
| 451 | |
| 452 | if (!queued) |
| 453 | kfree_skb(skb); |
| 454 | |
| 455 | return 0; |
| 456 | } |