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 processing. 19 * mar/20/00 Daniela Squassoni Disabling/enabling of facilities 20 * negotiation. 21 * jun/24/01 Arnaldo C. Melo use skb_queue_purge, cleanups 22 * apr/04/15 Shaun Pereira Fast select with no 23 * restriction on response. 24 */ 25 26 #define pr_fmt(fmt) "X25: " fmt 27 28 #include <linux/slab.h> 29 #include <linux/kernel.h> 30 #include <linux/string.h> 31 #include <linux/skbuff.h> 32 #include <net/sock.h> 33 #include <net/tcp_states.h> 34 #include <net/x25.h> 35 36 /* 37 * This routine purges all of the queues of frames. 38 */ 39 void x25_clear_queues(struct sock *sk) 40 { 41 struct x25_sock *x25 = x25_sk(sk); 42 43 skb_queue_purge(&sk->sk_write_queue); 44 skb_queue_purge(&x25->ack_queue); 45 skb_queue_purge(&x25->interrupt_in_queue); 46 skb_queue_purge(&x25->interrupt_out_queue); 47 skb_queue_purge(&x25->fragment_queue); 48 } 49 50 51 /* 52 * This routine purges the input queue of those frames that have been 53 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the 54 * SDL diagram. 55 */ 56 void x25_frames_acked(struct sock *sk, unsigned short nr) 57 { 58 struct sk_buff *skb; 59 struct x25_sock *x25 = x25_sk(sk); 60 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS; 61 62 /* 63 * Remove all the ack-ed frames from the ack queue. 64 */ 65 if (x25->va != nr) 66 while (skb_peek(&x25->ack_queue) && x25->va != nr) { 67 skb = skb_dequeue(&x25->ack_queue); 68 kfree_skb(skb); 69 x25->va = (x25->va + 1) % modulus; 70 } 71 } 72 73 void x25_requeue_frames(struct sock *sk) 74 { 75 struct sk_buff *skb, *skb_prev = NULL; 76 77 /* 78 * Requeue all the un-ack-ed frames on the output queue to be picked 79 * up by x25_kick. This arrangement handles the possibility of an empty 80 * output queue. 81 */ 82 while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) { 83 if (!skb_prev) 84 skb_queue_head(&sk->sk_write_queue, skb); 85 else 86 skb_append(skb_prev, skb, &sk->sk_write_queue); 87 skb_prev = skb; 88 } 89 } 90 91 /* 92 * Validate that the value of nr is between va and vs. Return true or 93 * false for testing. 94 */ 95 int x25_validate_nr(struct sock *sk, unsigned short nr) 96 { 97 struct x25_sock *x25 = x25_sk(sk); 98 unsigned short vc = x25->va; 99 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS; 100 101 while (vc != x25->vs) { 102 if (nr == vc) 103 return 1; 104 vc = (vc + 1) % modulus; 105 } 106 107 return nr == x25->vs ? 1 : 0; 108 } 109 110 /* 111 * This routine is called when the packet layer internally generates a 112 * control frame. 113 */ 114 void x25_write_internal(struct sock *sk, int frametype) 115 { 116 struct x25_sock *x25 = x25_sk(sk); 117 struct sk_buff *skb; 118 unsigned char *dptr; 119 unsigned char facilities[X25_MAX_FAC_LEN]; 120 unsigned char addresses[1 + X25_ADDR_LEN]; 121 unsigned char lci1, lci2; 122 /* 123 * Default safe frame size. 124 */ 125 int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN; 126 127 /* 128 * Adjust frame size. 129 */ 130 switch (frametype) { 131 case X25_CALL_REQUEST: 132 len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN; 133 break; 134 case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */ 135 if (x25->facilities.reverse & 0x80) { 136 len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN; 137 } else { 138 len += 1 + X25_MAX_FAC_LEN; 139 } 140 break; 141 case X25_CLEAR_REQUEST: 142 case X25_RESET_REQUEST: 143 len += 2; 144 break; 145 case X25_RR: 146 case X25_RNR: 147 case X25_REJ: 148 case X25_CLEAR_CONFIRMATION: 149 case X25_INTERRUPT_CONFIRMATION: 150 case X25_RESET_CONFIRMATION: 151 break; 152 default: 153 pr_err("invalid frame type %02X\n", frametype); 154 return; 155 } 156 157 if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL) 158 return; 159 160 /* 161 * Space for Ethernet and 802.2 LLC headers. 162 */ 163 skb_reserve(skb, X25_MAX_L2_LEN); 164 165 /* 166 * Make space for the GFI and LCI, and fill them in. 167 */ 168 dptr = skb_put(skb, 2); 169 170 lci1 = (x25->lci >> 8) & 0x0F; 171 lci2 = (x25->lci >> 0) & 0xFF; 172 173 if (x25->neighbour->extended) { 174 *dptr++ = lci1 | X25_GFI_EXTSEQ; 175 *dptr++ = lci2; 176 } else { 177 *dptr++ = lci1 | X25_GFI_STDSEQ; 178 *dptr++ = lci2; 179 } 180 181 /* 182 * Now fill in the frame type specific information. 183 */ 184 switch (frametype) { 185 186 case X25_CALL_REQUEST: 187 dptr = skb_put(skb, 1); 188 *dptr++ = X25_CALL_REQUEST; 189 len = x25_addr_aton(addresses, &x25->dest_addr, 190 &x25->source_addr); 191 dptr = skb_put_data(skb, addresses, len); 192 len = x25_create_facilities(facilities, 193 &x25->facilities, 194 &x25->dte_facilities, 195 x25->neighbour->global_facil_mask); 196 dptr = skb_put_data(skb, facilities, len); 197 dptr = skb_put_data(skb, x25->calluserdata.cuddata, 198 x25->calluserdata.cudlength); 199 x25->calluserdata.cudlength = 0; 200 break; 201 202 case X25_CALL_ACCEPTED: 203 dptr = skb_put(skb, 2); 204 *dptr++ = X25_CALL_ACCEPTED; 205 *dptr++ = 0x00; /* Address lengths */ 206 len = x25_create_facilities(facilities, 207 &x25->facilities, 208 &x25->dte_facilities, 209 x25->vc_facil_mask); 210 dptr = skb_put_data(skb, facilities, len); 211 212 /* fast select with no restriction on response 213 allows call user data. Userland must 214 ensure it is ours and not theirs */ 215 if(x25->facilities.reverse & 0x80) { 216 dptr = skb_put_data(skb, 217 x25->calluserdata.cuddata, 218 x25->calluserdata.cudlength); 219 } 220 x25->calluserdata.cudlength = 0; 221 break; 222 223 case X25_CLEAR_REQUEST: 224 dptr = skb_put(skb, 3); 225 *dptr++ = frametype; 226 *dptr++ = x25->causediag.cause; 227 *dptr++ = x25->causediag.diagnostic; 228 break; 229 230 case X25_RESET_REQUEST: 231 dptr = skb_put(skb, 3); 232 *dptr++ = frametype; 233 *dptr++ = 0x00; /* XXX */ 234 *dptr++ = 0x00; /* XXX */ 235 break; 236 237 case X25_RR: 238 case X25_RNR: 239 case X25_REJ: 240 if (x25->neighbour->extended) { 241 dptr = skb_put(skb, 2); 242 *dptr++ = frametype; 243 *dptr++ = (x25->vr << 1) & 0xFE; 244 } else { 245 dptr = skb_put(skb, 1); 246 *dptr = frametype; 247 *dptr++ |= (x25->vr << 5) & 0xE0; 248 } 249 break; 250 251 case X25_CLEAR_CONFIRMATION: 252 case X25_INTERRUPT_CONFIRMATION: 253 case X25_RESET_CONFIRMATION: 254 dptr = skb_put(skb, 1); 255 *dptr = frametype; 256 break; 257 } 258 259 x25_transmit_link(skb, x25->neighbour); 260 } 261 262 /* 263 * Unpick the contents of the passed X.25 Packet Layer frame. 264 */ 265 int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q, 266 int *d, int *m) 267 { 268 struct x25_sock *x25 = x25_sk(sk); 269 unsigned char *frame; 270 271 if (!pskb_may_pull(skb, X25_STD_MIN_LEN)) 272 return X25_ILLEGAL; 273 frame = skb->data; 274 275 *ns = *nr = *q = *d = *m = 0; 276 277 switch (frame[2]) { 278 case X25_CALL_REQUEST: 279 case X25_CALL_ACCEPTED: 280 case X25_CLEAR_REQUEST: 281 case X25_CLEAR_CONFIRMATION: 282 case X25_INTERRUPT: 283 case X25_INTERRUPT_CONFIRMATION: 284 case X25_RESET_REQUEST: 285 case X25_RESET_CONFIRMATION: 286 case X25_RESTART_REQUEST: 287 case X25_RESTART_CONFIRMATION: 288 case X25_REGISTRATION_REQUEST: 289 case X25_REGISTRATION_CONFIRMATION: 290 case X25_DIAGNOSTIC: 291 return frame[2]; 292 } 293 294 if (x25->neighbour->extended) { 295 if (frame[2] == X25_RR || 296 frame[2] == X25_RNR || 297 frame[2] == X25_REJ) { 298 if (!pskb_may_pull(skb, X25_EXT_MIN_LEN)) 299 return X25_ILLEGAL; 300 frame = skb->data; 301 302 *nr = (frame[3] >> 1) & 0x7F; 303 return frame[2]; 304 } 305 } else { 306 if ((frame[2] & 0x1F) == X25_RR || 307 (frame[2] & 0x1F) == X25_RNR || 308 (frame[2] & 0x1F) == X25_REJ) { 309 *nr = (frame[2] >> 5) & 0x07; 310 return frame[2] & 0x1F; 311 } 312 } 313 314 if (x25->neighbour->extended) { 315 if ((frame[2] & 0x01) == X25_DATA) { 316 if (!pskb_may_pull(skb, X25_EXT_MIN_LEN)) 317 return X25_ILLEGAL; 318 frame = skb->data; 319 320 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT; 321 *d = (frame[0] & X25_D_BIT) == X25_D_BIT; 322 *m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT; 323 *nr = (frame[3] >> 1) & 0x7F; 324 *ns = (frame[2] >> 1) & 0x7F; 325 return X25_DATA; 326 } 327 } else { 328 if ((frame[2] & 0x01) == X25_DATA) { 329 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT; 330 *d = (frame[0] & X25_D_BIT) == X25_D_BIT; 331 *m = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT; 332 *nr = (frame[2] >> 5) & 0x07; 333 *ns = (frame[2] >> 1) & 0x07; 334 return X25_DATA; 335 } 336 } 337 338 pr_debug("invalid PLP frame %02X %02X %02X\n", 339 frame[0], frame[1], frame[2]); 340 341 return X25_ILLEGAL; 342 } 343 344 void x25_disconnect(struct sock *sk, int reason, unsigned char cause, 345 unsigned char diagnostic) 346 { 347 struct x25_sock *x25 = x25_sk(sk); 348 349 x25_clear_queues(sk); 350 x25_stop_timer(sk); 351 352 x25->lci = 0; 353 x25->state = X25_STATE_0; 354 355 x25->causediag.cause = cause; 356 x25->causediag.diagnostic = diagnostic; 357 358 sk->sk_state = TCP_CLOSE; 359 sk->sk_err = reason; 360 sk->sk_shutdown |= SEND_SHUTDOWN; 361 362 if (!sock_flag(sk, SOCK_DEAD)) { 363 sk->sk_state_change(sk); 364 sock_set_flag(sk, SOCK_DEAD); 365 } 366 } 367 368 /* 369 * Clear an own-rx-busy condition and tell the peer about this, provided 370 * that there is a significant amount of free receive buffer space available. 371 */ 372 void x25_check_rbuf(struct sock *sk) 373 { 374 struct x25_sock *x25 = x25_sk(sk); 375 376 if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf >> 1) && 377 (x25->condition & X25_COND_OWN_RX_BUSY)) { 378 x25->condition &= ~X25_COND_OWN_RX_BUSY; 379 x25->condition &= ~X25_COND_ACK_PENDING; 380 x25->vl = x25->vr; 381 x25_write_internal(sk, X25_RR); 382 x25_stop_timer(sk); 383 } 384 } 385 386