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_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                         /* fall through */
 349                 case X25_RESET_CONFIRMATION: {
 350                         x25_stop_timer(sk);
 351                         x25->condition = 0x00;
 352                         x25->va        = 0;
 353                         x25->vr        = 0;
 354                         x25->vs        = 0;
 355                         x25->vl        = 0;
 356                         x25->state     = X25_STATE_3;
 357                         x25_requeue_frames(sk);
 358                         break;
 359                 }
 360                 case X25_CLEAR_REQUEST:
 361                         if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
 362                                 goto out_clear;
 363
 364                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 365                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 366                         break;
 367
 368                 default:
 369                         break;
 370         }
 371
 372         return 0;
 373
 374 out_clear:
 375         x25_write_internal(sk, X25_CLEAR_REQUEST);
 376         x25->state = X25_STATE_2;
 377         x25_start_t23timer(sk);
 378         return 0;
 379 }
 380
 381 /* Higher level upcall for a LAPB frame */
 382 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
 383 {
 384         struct x25_sock *x25 = x25_sk(sk);
 385         int queued = 0, frametype, ns, nr, q, d, m;
 386
 387         if (x25->state == X25_STATE_0)
 388                 return 0;
 389
 390         frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
 391
 392         switch (x25->state) {
 393         case X25_STATE_1:
 394                 queued = x25_state1_machine(sk, skb, frametype);
 395                 break;
 396         case X25_STATE_2:
 397                 queued = x25_state2_machine(sk, skb, frametype);
 398                 break;
 399         case X25_STATE_3:
 400                 queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
 401                 break;
 402         case X25_STATE_4:
 403                 queued = x25_state4_machine(sk, skb, frametype);
 404                 break;
 405         }
 406
 407         x25_kick(sk);
 408
 409         return queued;
 410 }
 411
 412 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 413 {
 414         int queued = x25_process_rx_frame(sk, skb);
 415
 416         if (!queued)
 417                 kfree_skb(skb);
 418
 419         return 0;
 420 }