net/netrom/nr_in.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *
   4  * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   5  * Copyright Darryl Miles G7LED (dlm@g7led.demon.co.uk)
   6  */
   7 #include <linux/errno.h>
   8 #include <linux/types.h>
   9 #include <linux/socket.h>
  10 #include <linux/in.h>
  11 #include <linux/kernel.h>
  12 #include <linux/timer.h>
  13 #include <linux/string.h>
  14 #include <linux/sockios.h>
  15 #include <linux/net.h>
  16 #include <linux/slab.h>
  17 #include <net/ax25.h>
  18 #include <linux/inet.h>
  19 #include <linux/netdevice.h>
  20 #include <linux/skbuff.h>
  21 #include <net/sock.h>
  22 #include <net/tcp_states.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/fcntl.h>
  25 #include <linux/mm.h>
  26 #include <linux/interrupt.h>
  27 #include <net/netrom.h>
  28
  29 static int nr_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
  30 {
  31         struct sk_buff *skbo, *skbn = skb;
  32         struct nr_sock *nr = nr_sk(sk);
  33
  34         skb_pull(skb, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
  35
  36         nr_start_idletimer(sk);
  37
  38         if (more) {
  39                 nr->fraglen += skb->len;
  40                 skb_queue_tail(&nr->frag_queue, skb);
  41                 return 0;
  42         }
  43
  44         if (!more && nr->fraglen > 0) { /* End of fragment */
  45                 nr->fraglen += skb->len;
  46                 skb_queue_tail(&nr->frag_queue, skb);
  47
  48                 if ((skbn = alloc_skb(nr->fraglen, GFP_ATOMIC)) == NULL)
  49                         return 1;
  50
  51                 skb_reset_transport_header(skbn);
  52
  53                 while ((skbo = skb_dequeue(&nr->frag_queue)) != NULL) {
  54                         skb_copy_from_linear_data(skbo,
  55                                                   skb_put(skbn, skbo->len),
  56                                                   skbo->len);
  57                         kfree_skb(skbo);
  58                 }
  59
  60                 nr->fraglen = 0;
  61         }
  62
  63         return sock_queue_rcv_skb(sk, skbn);
  64 }
  65
  66 /*
  67  * State machine for state 1, Awaiting Connection State.
  68  * The handling of the timer(s) is in file nr_timer.c.
  69  * Handling of state 0 and connection release is in netrom.c.
  70  */
  71 static int nr_state1_machine(struct sock *sk, struct sk_buff *skb,
  72         int frametype)
  73 {
  74         switch (frametype) {
  75         case NR_CONNACK: {
  76                 struct nr_sock *nr = nr_sk(sk);
  77
  78                 nr_stop_t1timer(sk);
  79                 nr_start_idletimer(sk);
  80                 nr->your_index = skb->data[17];
  81                 nr->your_id    = skb->data[18];
  82                 nr->vs         = 0;
  83                 nr->va         = 0;
  84                 nr->vr         = 0;
  85                 nr->vl         = 0;
  86                 nr->state      = NR_STATE_3;
  87                 nr->n2count    = 0;
  88                 nr->window     = skb->data[20];
  89                 sk->sk_state   = TCP_ESTABLISHED;
  90                 if (!sock_flag(sk, SOCK_DEAD))
  91                         sk->sk_state_change(sk);
  92                 break;
  93         }
  94
  95         case NR_CONNACK | NR_CHOKE_FLAG:
  96                 nr_disconnect(sk, ECONNREFUSED);
  97                 break;
  98
  99         case NR_RESET:
 100                 if (sysctl_netrom_reset_circuit)
 101                         nr_disconnect(sk, ECONNRESET);
 102                 break;
 103
 104         default:
 105                 break;
 106         }
 107         return 0;
 108 }
 109
 110 /*
 111  * State machine for state 2, Awaiting Release State.
 112  * The handling of the timer(s) is in file nr_timer.c
 113  * Handling of state 0 and connection release is in netrom.c.
 114  */
 115 static int nr_state2_machine(struct sock *sk, struct sk_buff *skb,
 116         int frametype)
 117 {
 118         switch (frametype) {
 119         case NR_CONNACK | NR_CHOKE_FLAG:
 120                 nr_disconnect(sk, ECONNRESET);
 121                 break;
 122
 123         case NR_DISCREQ:
 124                 nr_write_internal(sk, NR_DISCACK);
 125                 fallthrough;
 126         case NR_DISCACK:
 127                 nr_disconnect(sk, 0);
 128                 break;
 129
 130         case NR_RESET:
 131                 if (sysctl_netrom_reset_circuit)
 132                         nr_disconnect(sk, ECONNRESET);
 133                 break;
 134
 135         default:
 136                 break;
 137         }
 138         return 0;
 139 }
 140
 141 /*
 142  * State machine for state 3, Connected State.
 143  * The handling of the timer(s) is in file nr_timer.c
 144  * Handling of state 0 and connection release is in netrom.c.
 145  */
 146 static int nr_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 147 {
 148         struct nr_sock *nrom = nr_sk(sk);
 149         struct sk_buff_head temp_queue;
 150         struct sk_buff *skbn;
 151         unsigned short save_vr;
 152         unsigned short nr, ns;
 153         int queued = 0;
 154
 155         nr = skb->data[18];
 156         ns = skb->data[17];
 157
 158         switch (frametype) {
 159         case NR_CONNREQ:
 160                 nr_write_internal(sk, NR_CONNACK);
 161                 break;
 162
 163         case NR_DISCREQ:
 164                 nr_write_internal(sk, NR_DISCACK);
 165                 nr_disconnect(sk, 0);
 166                 break;
 167
 168         case NR_CONNACK | NR_CHOKE_FLAG:
 169         case NR_DISCACK:
 170                 nr_disconnect(sk, ECONNRESET);
 171                 break;
 172
 173         case NR_INFOACK:
 174         case NR_INFOACK | NR_CHOKE_FLAG:
 175         case NR_INFOACK | NR_NAK_FLAG:
 176         case NR_INFOACK | NR_NAK_FLAG | NR_CHOKE_FLAG:
 177                 if (frametype & NR_CHOKE_FLAG) {
 178                         nrom->condition |= NR_COND_PEER_RX_BUSY;
 179                         nr_start_t4timer(sk);
 180                 } else {
 181                         nrom->condition &= ~NR_COND_PEER_RX_BUSY;
 182                         nr_stop_t4timer(sk);
 183                 }
 184                 if (!nr_validate_nr(sk, nr)) {
 185                         break;
 186                 }
 187                 if (frametype & NR_NAK_FLAG) {
 188                         nr_frames_acked(sk, nr);
 189                         nr_send_nak_frame(sk);
 190                 } else {
 191                         if (nrom->condition & NR_COND_PEER_RX_BUSY) {
 192                                 nr_frames_acked(sk, nr);
 193                         } else {
 194                                 nr_check_iframes_acked(sk, nr);
 195                         }
 196                 }
 197                 break;
 198
 199         case NR_INFO:
 200         case NR_INFO | NR_NAK_FLAG:
 201         case NR_INFO | NR_CHOKE_FLAG:
 202         case NR_INFO | NR_MORE_FLAG:
 203         case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG:
 204         case NR_INFO | NR_CHOKE_FLAG | NR_MORE_FLAG:
 205         case NR_INFO | NR_NAK_FLAG | NR_MORE_FLAG:
 206         case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG | NR_MORE_FLAG:
 207                 if (frametype & NR_CHOKE_FLAG) {
 208                         nrom->condition |= NR_COND_PEER_RX_BUSY;
 209                         nr_start_t4timer(sk);
 210                 } else {
 211                         nrom->condition &= ~NR_COND_PEER_RX_BUSY;
 212                         nr_stop_t4timer(sk);
 213                 }
 214                 if (nr_validate_nr(sk, nr)) {
 215                         if (frametype & NR_NAK_FLAG) {
 216                                 nr_frames_acked(sk, nr);
 217                                 nr_send_nak_frame(sk);
 218                         } else {
 219                                 if (nrom->condition & NR_COND_PEER_RX_BUSY) {
 220                                         nr_frames_acked(sk, nr);
 221                                 } else {
 222                                         nr_check_iframes_acked(sk, nr);
 223                                 }
 224                         }
 225                 }
 226                 queued = 1;
 227                 skb_queue_head(&nrom->reseq_queue, skb);
 228                 if (nrom->condition & NR_COND_OWN_RX_BUSY)
 229                         break;
 230                 skb_queue_head_init(&temp_queue);
 231                 do {
 232                         save_vr = nrom->vr;
 233                         while ((skbn = skb_dequeue(&nrom->reseq_queue)) != NULL) {
 234                                 ns = skbn->data[17];
 235                                 if (ns == nrom->vr) {
 236                                         if (nr_queue_rx_frame(sk, skbn, frametype & NR_MORE_FLAG) == 0) {
 237                                                 nrom->vr = (nrom->vr + 1) % NR_MODULUS;
 238                                         } else {
 239                                                 nrom->condition |= NR_COND_OWN_RX_BUSY;
 240                                                 skb_queue_tail(&temp_queue, skbn);
 241                                         }
 242                                 } else if (nr_in_rx_window(sk, ns)) {
 243                                         skb_queue_tail(&temp_queue, skbn);
 244                                 } else {
 245                                         kfree_skb(skbn);
 246                                 }
 247                         }
 248                         while ((skbn = skb_dequeue(&temp_queue)) != NULL) {
 249                                 skb_queue_tail(&nrom->reseq_queue, skbn);
 250                         }
 251                 } while (save_vr != nrom->vr);
 252                 /*
 253                  * Window is full, ack it immediately.
 254                  */
 255                 if (((nrom->vl + nrom->window) % NR_MODULUS) == nrom->vr) {
 256                         nr_enquiry_response(sk);
 257                 } else {
 258                         if (!(nrom->condition & NR_COND_ACK_PENDING)) {
 259                                 nrom->condition |= NR_COND_ACK_PENDING;
 260                                 nr_start_t2timer(sk);
 261                         }
 262                 }
 263                 break;
 264
 265         case NR_RESET:
 266                 if (sysctl_netrom_reset_circuit)
 267                         nr_disconnect(sk, ECONNRESET);
 268                 break;
 269
 270         default:
 271                 break;
 272         }
 273         return queued;
 274 }
 275
 276 /* Higher level upcall for a LAPB frame - called with sk locked */
 277 int nr_process_rx_frame(struct sock *sk, struct sk_buff *skb)
 278 {
 279         struct nr_sock *nr = nr_sk(sk);
 280         int queued = 0, frametype;
 281
 282         if (nr->state == NR_STATE_0)
 283                 return 0;
 284
 285         frametype = skb->data[19];
 286
 287         switch (nr->state) {
 288         case NR_STATE_1:
 289                 queued = nr_state1_machine(sk, skb, frametype);
 290                 break;
 291         case NR_STATE_2:
 292                 queued = nr_state2_machine(sk, skb, frametype);
 293                 break;
 294         case NR_STATE_3:
 295                 queued = nr_state3_machine(sk, skb, frametype);
 296                 break;
 297         }
 298
 299         nr_kick(sk);
 300
 301         return queued;
 302 }