net/x25/x25_in.c

   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 }