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
 157         switch (frametype) {
 158         case NR_CONNREQ:
 159                 nr_write_internal(sk, NR_CONNACK);
 160                 break;
 161
 162         case NR_DISCREQ:
 163                 nr_write_internal(sk, NR_DISCACK);
 164                 nr_disconnect(sk, 0);
 165                 break;
 166
 167         case NR_CONNACK | NR_CHOKE_FLAG:
 168         case NR_DISCACK:
 169                 nr_disconnect(sk, ECONNRESET);
 170                 break;
 171
 172         case NR_INFOACK:
 173         case NR_INFOACK | NR_CHOKE_FLAG:
 174         case NR_INFOACK | NR_NAK_FLAG:
 175         case NR_INFOACK | NR_NAK_FLAG | NR_CHOKE_FLAG:
 176                 if (frametype & NR_CHOKE_FLAG) {
 177                         nrom->condition |= NR_COND_PEER_RX_BUSY;
 178                         nr_start_t4timer(sk);
 179                 } else {
 180                         nrom->condition &= ~NR_COND_PEER_RX_BUSY;
 181                         nr_stop_t4timer(sk);
 182                 }
 183                 if (!nr_validate_nr(sk, nr)) {
 184                         break;
 185                 }
 186                 if (frametype & NR_NAK_FLAG) {
 187                         nr_frames_acked(sk, nr);
 188                         nr_send_nak_frame(sk);
 189                 } else {
 190                         if (nrom->condition & NR_COND_PEER_RX_BUSY) {
 191                                 nr_frames_acked(sk, nr);
 192                         } else {
 193                                 nr_check_iframes_acked(sk, nr);
 194                         }
 195                 }
 196                 break;
 197
 198         case NR_INFO:
 199         case NR_INFO | NR_NAK_FLAG:
 200         case NR_INFO | NR_CHOKE_FLAG:
 201         case NR_INFO | NR_MORE_FLAG:
 202         case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG:
 203         case NR_INFO | NR_CHOKE_FLAG | NR_MORE_FLAG:
 204         case NR_INFO | NR_NAK_FLAG | NR_MORE_FLAG:
 205         case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG | NR_MORE_FLAG:
 206                 if (frametype & NR_CHOKE_FLAG) {
 207                         nrom->condition |= NR_COND_PEER_RX_BUSY;
 208                         nr_start_t4timer(sk);
 209                 } else {
 210                         nrom->condition &= ~NR_COND_PEER_RX_BUSY;
 211                         nr_stop_t4timer(sk);
 212                 }
 213                 if (nr_validate_nr(sk, nr)) {
 214                         if (frametype & NR_NAK_FLAG) {
 215                                 nr_frames_acked(sk, nr);
 216                                 nr_send_nak_frame(sk);
 217                         } else {
 218                                 if (nrom->condition & NR_COND_PEER_RX_BUSY) {
 219                                         nr_frames_acked(sk, nr);
 220                                 } else {
 221                                         nr_check_iframes_acked(sk, nr);
 222                                 }
 223                         }
 224                 }
 225                 queued = 1;
 226                 skb_queue_head(&nrom->reseq_queue, skb);
 227                 if (nrom->condition & NR_COND_OWN_RX_BUSY)
 228                         break;
 229                 skb_queue_head_init(&temp_queue);
 230                 do {
 231                         save_vr = nrom->vr;
 232                         while ((skbn = skb_dequeue(&nrom->reseq_queue)) != NULL) {
 233                                 ns = skbn->data[17];
 234                                 if (ns == nrom->vr) {
 235                                         if (nr_queue_rx_frame(sk, skbn, frametype & NR_MORE_FLAG) == 0) {
 236                                                 nrom->vr = (nrom->vr + 1) % NR_MODULUS;
 237                                         } else {
 238                                                 nrom->condition |= NR_COND_OWN_RX_BUSY;
 239                                                 skb_queue_tail(&temp_queue, skbn);
 240                                         }
 241                                 } else if (nr_in_rx_window(sk, ns)) {
 242                                         skb_queue_tail(&temp_queue, skbn);
 243                                 } else {
 244                                         kfree_skb(skbn);
 245                                 }
 246                         }
 247                         while ((skbn = skb_dequeue(&temp_queue)) != NULL) {
 248                                 skb_queue_tail(&nrom->reseq_queue, skbn);
 249                         }
 250                 } while (save_vr != nrom->vr);
 251                 /*
 252                  * Window is full, ack it immediately.
 253                  */
 254                 if (((nrom->vl + nrom->window) % NR_MODULUS) == nrom->vr) {
 255                         nr_enquiry_response(sk);
 256                 } else {
 257                         if (!(nrom->condition & NR_COND_ACK_PENDING)) {
 258                                 nrom->condition |= NR_COND_ACK_PENDING;
 259                                 nr_start_t2timer(sk);
 260                         }
 261                 }
 262                 break;
 263
 264         case NR_RESET:
 265                 if (sysctl_netrom_reset_circuit)
 266                         nr_disconnect(sk, ECONNRESET);
 267                 break;
 268
 269         default:
 270                 break;
 271         }
 272         return queued;
 273 }
 274
 275 /* Higher level upcall for a LAPB frame - called with sk locked */
 276 int nr_process_rx_frame(struct sock *sk, struct sk_buff *skb)
 277 {
 278         struct nr_sock *nr = nr_sk(sk);
 279         int queued = 0, frametype;
 280
 281         if (nr->state == NR_STATE_0)
 282                 return 0;
 283
 284         frametype = skb->data[19];
 285
 286         switch (nr->state) {
 287         case NR_STATE_1:
 288                 queued = nr_state1_machine(sk, skb, frametype);
 289                 break;
 290         case NR_STATE_2:
 291                 queued = nr_state2_machine(sk, skb, frametype);
 292                 break;
 293         case NR_STATE_3:
 294                 queued = nr_state3_machine(sk, skb, frametype);
 295                 break;
 296         }
 297
 298         nr_kick(sk);
 299
 300         return queued;
 301 }