| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
| 2 | /* |
| 3 | * |
| 4 | * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk) |
| 5 | * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk) |
| 6 | * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de) |
| 7 | */ |
| 8 | #include <linux/errno.h> |
| 9 | #include <linux/types.h> |
| 10 | #include <linux/socket.h> |
| 11 | #include <linux/in.h> |
| 12 | #include <linux/kernel.h> |
| 13 | #include <linux/module.h> |
| 14 | #include <linux/timer.h> |
| 15 | #include <linux/string.h> |
| 16 | #include <linux/sockios.h> |
| 17 | #include <linux/spinlock.h> |
| 18 | #include <linux/net.h> |
| 19 | #include <linux/slab.h> |
| 20 | #include <net/ax25.h> |
| 21 | #include <linux/inet.h> |
| 22 | #include <linux/netdevice.h> |
| 23 | #include <linux/skbuff.h> |
| 24 | #include <net/sock.h> |
| 25 | #include <linux/uaccess.h> |
| 26 | #include <linux/fcntl.h> |
| 27 | #include <linux/mm.h> |
| 28 | #include <linux/interrupt.h> |
| 29 | |
| 30 | static DEFINE_SPINLOCK(ax25_frag_lock); |
| 31 | |
| 32 | ax25_cb *ax25_send_frame(struct sk_buff *skb, int paclen, const ax25_address *src, ax25_address *dest, ax25_digi *digi, struct net_device *dev) |
| 33 | { |
| 34 | ax25_dev *ax25_dev; |
| 35 | ax25_cb *ax25; |
| 36 | |
| 37 | /* |
| 38 | * Take the default packet length for the device if zero is |
| 39 | * specified. |
| 40 | */ |
| 41 | if (paclen == 0) { |
| 42 | if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) |
| 43 | return NULL; |
| 44 | |
| 45 | paclen = ax25_dev->values[AX25_VALUES_PACLEN]; |
| 46 | } |
| 47 | |
| 48 | /* |
| 49 | * Look for an existing connection. |
| 50 | */ |
| 51 | if ((ax25 = ax25_find_cb(src, dest, digi, dev)) != NULL) { |
| 52 | ax25_output(ax25, paclen, skb); |
| 53 | return ax25; /* It already existed */ |
| 54 | } |
| 55 | |
| 56 | if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) |
| 57 | return NULL; |
| 58 | |
| 59 | if ((ax25 = ax25_create_cb()) == NULL) |
| 60 | return NULL; |
| 61 | |
| 62 | ax25_fillin_cb(ax25, ax25_dev); |
| 63 | |
| 64 | ax25->source_addr = *src; |
| 65 | ax25->dest_addr = *dest; |
| 66 | |
| 67 | if (digi != NULL) { |
| 68 | ax25->digipeat = kmemdup(digi, sizeof(*digi), GFP_ATOMIC); |
| 69 | if (ax25->digipeat == NULL) { |
| 70 | ax25_cb_put(ax25); |
| 71 | return NULL; |
| 72 | } |
| 73 | } |
| 74 | |
| 75 | switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) { |
| 76 | case AX25_PROTO_STD_SIMPLEX: |
| 77 | case AX25_PROTO_STD_DUPLEX: |
| 78 | ax25_std_establish_data_link(ax25); |
| 79 | break; |
| 80 | |
| 81 | #ifdef CONFIG_AX25_DAMA_SLAVE |
| 82 | case AX25_PROTO_DAMA_SLAVE: |
| 83 | if (ax25_dev->dama.slave) |
| 84 | ax25_ds_establish_data_link(ax25); |
| 85 | else |
| 86 | ax25_std_establish_data_link(ax25); |
| 87 | break; |
| 88 | #endif |
| 89 | } |
| 90 | |
| 91 | /* |
| 92 | * There is one ref for the state machine; a caller needs |
| 93 | * one more to put it back, just like with the existing one. |
| 94 | */ |
| 95 | ax25_cb_hold(ax25); |
| 96 | |
| 97 | ax25_cb_add(ax25); |
| 98 | |
| 99 | ax25->state = AX25_STATE_1; |
| 100 | |
| 101 | ax25_start_heartbeat(ax25); |
| 102 | |
| 103 | ax25_output(ax25, paclen, skb); |
| 104 | |
| 105 | return ax25; /* We had to create it */ |
| 106 | } |
| 107 | |
| 108 | EXPORT_SYMBOL(ax25_send_frame); |
| 109 | |
| 110 | /* |
| 111 | * All outgoing AX.25 I frames pass via this routine. Therefore this is |
| 112 | * where the fragmentation of frames takes place. If fragment is set to |
| 113 | * zero then we are not allowed to do fragmentation, even if the frame |
| 114 | * is too large. |
| 115 | */ |
| 116 | void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb) |
| 117 | { |
| 118 | struct sk_buff *skbn; |
| 119 | unsigned char *p; |
| 120 | int frontlen, len, fragno, ka9qfrag, first = 1; |
| 121 | |
| 122 | if (paclen < 16) { |
| 123 | WARN_ON_ONCE(1); |
| 124 | kfree_skb(skb); |
| 125 | return; |
| 126 | } |
| 127 | |
| 128 | if ((skb->len - 1) > paclen) { |
| 129 | if (*skb->data == AX25_P_TEXT) { |
| 130 | skb_pull(skb, 1); /* skip PID */ |
| 131 | ka9qfrag = 0; |
| 132 | } else { |
| 133 | paclen -= 2; /* Allow for fragment control info */ |
| 134 | ka9qfrag = 1; |
| 135 | } |
| 136 | |
| 137 | fragno = skb->len / paclen; |
| 138 | if (skb->len % paclen == 0) fragno--; |
| 139 | |
| 140 | frontlen = skb_headroom(skb); /* Address space + CTRL */ |
| 141 | |
| 142 | while (skb->len > 0) { |
| 143 | spin_lock_bh(&ax25_frag_lock); |
| 144 | if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) { |
| 145 | spin_unlock_bh(&ax25_frag_lock); |
| 146 | printk(KERN_CRIT "AX.25: ax25_output - out of memory\n"); |
| 147 | return; |
| 148 | } |
| 149 | |
| 150 | if (skb->sk != NULL) |
| 151 | skb_set_owner_w(skbn, skb->sk); |
| 152 | |
| 153 | spin_unlock_bh(&ax25_frag_lock); |
| 154 | |
| 155 | len = (paclen > skb->len) ? skb->len : paclen; |
| 156 | |
| 157 | if (ka9qfrag == 1) { |
| 158 | skb_reserve(skbn, frontlen + 2); |
| 159 | skb_set_network_header(skbn, |
| 160 | skb_network_offset(skb)); |
| 161 | skb_copy_from_linear_data(skb, skb_put(skbn, len), len); |
| 162 | p = skb_push(skbn, 2); |
| 163 | |
| 164 | *p++ = AX25_P_SEGMENT; |
| 165 | |
| 166 | *p = fragno--; |
| 167 | if (first) { |
| 168 | *p |= AX25_SEG_FIRST; |
| 169 | first = 0; |
| 170 | } |
| 171 | } else { |
| 172 | skb_reserve(skbn, frontlen + 1); |
| 173 | skb_set_network_header(skbn, |
| 174 | skb_network_offset(skb)); |
| 175 | skb_copy_from_linear_data(skb, skb_put(skbn, len), len); |
| 176 | p = skb_push(skbn, 1); |
| 177 | *p = AX25_P_TEXT; |
| 178 | } |
| 179 | |
| 180 | skb_pull(skb, len); |
| 181 | skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */ |
| 182 | } |
| 183 | |
| 184 | kfree_skb(skb); |
| 185 | } else { |
| 186 | skb_queue_tail(&ax25->write_queue, skb); /* Throw it on the queue */ |
| 187 | } |
| 188 | |
| 189 | switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) { |
| 190 | case AX25_PROTO_STD_SIMPLEX: |
| 191 | case AX25_PROTO_STD_DUPLEX: |
| 192 | ax25_kick(ax25); |
| 193 | break; |
| 194 | |
| 195 | #ifdef CONFIG_AX25_DAMA_SLAVE |
| 196 | /* |
| 197 | * A DAMA slave is _required_ to work as normal AX.25L2V2 |
| 198 | * if no DAMA master is available. |
| 199 | */ |
| 200 | case AX25_PROTO_DAMA_SLAVE: |
| 201 | if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25); |
| 202 | break; |
| 203 | #endif |
| 204 | } |
| 205 | } |
| 206 | |
| 207 | /* |
| 208 | * This procedure is passed a buffer descriptor for an iframe. It builds |
| 209 | * the rest of the control part of the frame and then writes it out. |
| 210 | */ |
| 211 | static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit) |
| 212 | { |
| 213 | unsigned char *frame; |
| 214 | |
| 215 | if (skb == NULL) |
| 216 | return; |
| 217 | |
| 218 | skb_reset_network_header(skb); |
| 219 | |
| 220 | if (ax25->modulus == AX25_MODULUS) { |
| 221 | frame = skb_push(skb, 1); |
| 222 | |
| 223 | *frame = AX25_I; |
| 224 | *frame |= (poll_bit) ? AX25_PF : 0; |
| 225 | *frame |= (ax25->vr << 5); |
| 226 | *frame |= (ax25->vs << 1); |
| 227 | } else { |
| 228 | frame = skb_push(skb, 2); |
| 229 | |
| 230 | frame[0] = AX25_I; |
| 231 | frame[0] |= (ax25->vs << 1); |
| 232 | frame[1] = (poll_bit) ? AX25_EPF : 0; |
| 233 | frame[1] |= (ax25->vr << 1); |
| 234 | } |
| 235 | |
| 236 | ax25_start_idletimer(ax25); |
| 237 | |
| 238 | ax25_transmit_buffer(ax25, skb, AX25_COMMAND); |
| 239 | } |
| 240 | |
| 241 | void ax25_kick(ax25_cb *ax25) |
| 242 | { |
| 243 | struct sk_buff *skb, *skbn; |
| 244 | int last = 1; |
| 245 | unsigned short start, end, next; |
| 246 | |
| 247 | if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4) |
| 248 | return; |
| 249 | |
| 250 | if (ax25->condition & AX25_COND_PEER_RX_BUSY) |
| 251 | return; |
| 252 | |
| 253 | if (skb_peek(&ax25->write_queue) == NULL) |
| 254 | return; |
| 255 | |
| 256 | start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs; |
| 257 | end = (ax25->va + ax25->window) % ax25->modulus; |
| 258 | |
| 259 | if (start == end) |
| 260 | return; |
| 261 | |
| 262 | /* |
| 263 | * Transmit data until either we're out of data to send or |
| 264 | * the window is full. Send a poll on the final I frame if |
| 265 | * the window is filled. |
| 266 | */ |
| 267 | |
| 268 | /* |
| 269 | * Dequeue the frame and copy it. |
| 270 | * Check for race with ax25_clear_queues(). |
| 271 | */ |
| 272 | skb = skb_dequeue(&ax25->write_queue); |
| 273 | if (!skb) |
| 274 | return; |
| 275 | |
| 276 | ax25->vs = start; |
| 277 | |
| 278 | do { |
| 279 | if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) { |
| 280 | skb_queue_head(&ax25->write_queue, skb); |
| 281 | break; |
| 282 | } |
| 283 | |
| 284 | if (skb->sk != NULL) |
| 285 | skb_set_owner_w(skbn, skb->sk); |
| 286 | |
| 287 | next = (ax25->vs + 1) % ax25->modulus; |
| 288 | last = (next == end); |
| 289 | |
| 290 | /* |
| 291 | * Transmit the frame copy. |
| 292 | * bke 960114: do not set the Poll bit on the last frame |
| 293 | * in DAMA mode. |
| 294 | */ |
| 295 | switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) { |
| 296 | case AX25_PROTO_STD_SIMPLEX: |
| 297 | case AX25_PROTO_STD_DUPLEX: |
| 298 | ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF); |
| 299 | break; |
| 300 | |
| 301 | #ifdef CONFIG_AX25_DAMA_SLAVE |
| 302 | case AX25_PROTO_DAMA_SLAVE: |
| 303 | ax25_send_iframe(ax25, skbn, AX25_POLLOFF); |
| 304 | break; |
| 305 | #endif |
| 306 | } |
| 307 | |
| 308 | ax25->vs = next; |
| 309 | |
| 310 | /* |
| 311 | * Requeue the original data frame. |
| 312 | */ |
| 313 | skb_queue_tail(&ax25->ack_queue, skb); |
| 314 | |
| 315 | } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL); |
| 316 | |
| 317 | ax25->condition &= ~AX25_COND_ACK_PENDING; |
| 318 | |
| 319 | if (!ax25_t1timer_running(ax25)) { |
| 320 | ax25_stop_t3timer(ax25); |
| 321 | ax25_calculate_t1(ax25); |
| 322 | ax25_start_t1timer(ax25); |
| 323 | } |
| 324 | } |
| 325 | |
| 326 | void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type) |
| 327 | { |
| 328 | unsigned char *ptr; |
| 329 | int headroom; |
| 330 | |
| 331 | if (ax25->ax25_dev == NULL) { |
| 332 | ax25_disconnect(ax25, ENETUNREACH); |
| 333 | return; |
| 334 | } |
| 335 | |
| 336 | headroom = ax25_addr_size(ax25->digipeat); |
| 337 | |
| 338 | if (unlikely(skb_headroom(skb) < headroom)) { |
| 339 | skb = skb_expand_head(skb, headroom); |
| 340 | if (!skb) { |
| 341 | printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n"); |
| 342 | return; |
| 343 | } |
| 344 | } |
| 345 | |
| 346 | ptr = skb_push(skb, headroom); |
| 347 | |
| 348 | ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus); |
| 349 | |
| 350 | ax25_queue_xmit(skb, ax25->ax25_dev->dev); |
| 351 | } |
| 352 | |
| 353 | /* |
| 354 | * A small shim to dev_queue_xmit to add the KISS control byte, and do |
| 355 | * any packet forwarding in operation. |
| 356 | */ |
| 357 | void ax25_queue_xmit(struct sk_buff *skb, struct net_device *dev) |
| 358 | { |
| 359 | unsigned char *ptr; |
| 360 | |
| 361 | skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(dev)); |
| 362 | |
| 363 | ptr = skb_push(skb, 1); |
| 364 | *ptr = 0x00; /* KISS */ |
| 365 | |
| 366 | dev_queue_xmit(skb); |
| 367 | } |
| 368 | |
| 369 | int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr) |
| 370 | { |
| 371 | if (ax25->vs == nr) { |
| 372 | ax25_frames_acked(ax25, nr); |
| 373 | ax25_calculate_rtt(ax25); |
| 374 | ax25_stop_t1timer(ax25); |
| 375 | ax25_start_t3timer(ax25); |
| 376 | return 1; |
| 377 | } else { |
| 378 | if (ax25->va != nr) { |
| 379 | ax25_frames_acked(ax25, nr); |
| 380 | ax25_calculate_t1(ax25); |
| 381 | ax25_start_t1timer(ax25); |
| 382 | return 1; |
| 383 | } |
| 384 | } |
| 385 | return 0; |
| 386 | } |