1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * X.25 Packet Layer release 002 4 * 5 * This is ALPHA test software. This code may break your machine, 6 * randomly fail to work with new releases, misbehave and/or generally 7 * screw up. It might even work. 8 * 9 * This code REQUIRES 2.1.15 or higher 10 * 11 * History 12 * X.25 001 Jonathan Naylor Started coding. 13 * X.25 002 Jonathan Naylor Centralised disconnection processing. 14 * mar/20/00 Daniela Squassoni Disabling/enabling of facilities 15 * negotiation. 16 * jun/24/01 Arnaldo C. Melo use skb_queue_purge, cleanups 17 * apr/04/15 Shaun Pereira Fast select with no 18 * restriction on response. 19 */ 20 21 #define pr_fmt(fmt) "X25: " fmt 22 23 #include <linux/slab.h> 24 #include <linux/kernel.h> 25 #include <linux/string.h> 26 #include <linux/skbuff.h> 27 #include <net/sock.h> 28 #include <net/tcp_states.h> 29 #include <net/x25.h> 30 31 /* 32 * This routine purges all of the queues of frames. 33 */ 34 void x25_clear_queues(struct sock *sk) 35 { 36 struct x25_sock *x25 = x25_sk(sk); 37 38 skb_queue_purge(&sk->sk_write_queue); 39 skb_queue_purge(&x25->ack_queue); 40 skb_queue_purge(&x25->interrupt_in_queue); 41 skb_queue_purge(&x25->interrupt_out_queue); 42 skb_queue_purge(&x25->fragment_queue); 43 } 44 45 46 /* 47 * This routine purges the input queue of those frames that have been 48 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the 49 * SDL diagram. 50 */ 51 void x25_frames_acked(struct sock *sk, unsigned short nr) 52 { 53 struct sk_buff *skb; 54 struct x25_sock *x25 = x25_sk(sk); 55 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS; 56 57 /* 58 * Remove all the ack-ed frames from the ack queue. 59 */ 60 if (x25->va != nr) 61 while (skb_peek(&x25->ack_queue) && x25->va != nr) { 62 skb = skb_dequeue(&x25->ack_queue); 63 kfree_skb(skb); 64 x25->va = (x25->va + 1) % modulus; 65 } 66 } 67 68 void x25_requeue_frames(struct sock *sk) 69 { 70 struct sk_buff *skb, *skb_prev = NULL; 71 72 /* 73 * Requeue all the un-ack-ed frames on the output queue to be picked 74 * up by x25_kick. This arrangement handles the possibility of an empty 75 * output queue. 76 */ 77 while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) { 78 if (!skb_prev) 79 skb_queue_head(&sk->sk_write_queue, skb); 80 else 81 skb_append(skb_prev, skb, &sk->sk_write_queue); 82 skb_prev = skb; 83 } 84 } 85 86 /* 87 * Validate that the value of nr is between va and vs. Return true or 88 * false for testing. 89 */ 90 int x25_validate_nr(struct sock *sk, unsigned short nr) 91 { 92 struct x25_sock *x25 = x25_sk(sk); 93 unsigned short vc = x25->va; 94 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS; 95 96 while (vc != x25->vs) { 97 if (nr == vc) 98 return 1; 99 vc = (vc + 1) % modulus; 100 } 101 102 return nr == x25->vs ? 1 : 0; 103 } 104 105 /* 106 * This routine is called when the packet layer internally generates a 107 * control frame. 108 */ 109 void x25_write_internal(struct sock *sk, int frametype) 110 { 111 struct x25_sock *x25 = x25_sk(sk); 112 struct sk_buff *skb; 113 unsigned char *dptr; 114 unsigned char facilities[X25_MAX_FAC_LEN]; 115 unsigned char addresses[1 + X25_ADDR_LEN]; 116 unsigned char lci1, lci2; 117 /* 118 * Default safe frame size. 119 */ 120 int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN; 121 122 /* 123 * Adjust frame size. 124 */ 125 switch (frametype) { 126 case X25_CALL_REQUEST: 127 len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN; 128 break; 129 case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */ 130 if (x25->facilities.reverse & 0x80) { 131 len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN; 132 } else { 133 len += 1 + X25_MAX_FAC_LEN; 134 } 135 break; 136 case X25_CLEAR_REQUEST: 137 case X25_RESET_REQUEST: 138 len += 2; 139 break; 140 case X25_RR: 141 case X25_RNR: 142 case X25_REJ: 143 case X25_CLEAR_CONFIRMATION: 144 case X25_INTERRUPT_CONFIRMATION: 145 case X25_RESET_CONFIRMATION: 146 break; 147 default: 148 pr_err("invalid frame type %02X\n", frametype); 149 return; 150 } 151 152 if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL) 153 return; 154 155 /* 156 * Space for Ethernet and 802.2 LLC headers. 157 */ 158 skb_reserve(skb, X25_MAX_L2_LEN); 159 160 /* 161 * Make space for the GFI and LCI, and fill them in. 162 */ 163 dptr = skb_put(skb, 2); 164 165 lci1 = (x25->lci >> 8) & 0x0F; 166 lci2 = (x25->lci >> 0) & 0xFF; 167 168 if (x25->neighbour->extended) { 169 *dptr++ = lci1 | X25_GFI_EXTSEQ; 170 *dptr++ = lci2; 171 } else { 172 *dptr++ = lci1 | X25_GFI_STDSEQ; 173 *dptr++ = lci2; 174 } 175 176 /* 177 * Now fill in the frame type specific information. 178 */ 179 switch (frametype) { 180 181 case X25_CALL_REQUEST: 182 dptr = skb_put(skb, 1); 183 *dptr++ = X25_CALL_REQUEST; 184 len = x25_addr_aton(addresses, &x25->dest_addr, 185 &x25->source_addr); 186 skb_put_data(skb, addresses, len); 187 len = x25_create_facilities(facilities, 188 &x25->facilities, 189 &x25->dte_facilities, 190 x25->neighbour->global_facil_mask); 191 skb_put_data(skb, facilities, len); 192 skb_put_data(skb, x25->calluserdata.cuddata, 193 x25->calluserdata.cudlength); 194 x25->calluserdata.cudlength = 0; 195 break; 196 197 case X25_CALL_ACCEPTED: 198 dptr = skb_put(skb, 2); 199 *dptr++ = X25_CALL_ACCEPTED; 200 *dptr++ = 0x00; /* Address lengths */ 201 len = x25_create_facilities(facilities, 202 &x25->facilities, 203 &x25->dte_facilities, 204 x25->vc_facil_mask); 205 skb_put_data(skb, facilities, len); 206 207 /* fast select with no restriction on response 208 allows call user data. Userland must 209 ensure it is ours and not theirs */ 210 if(x25->facilities.reverse & 0x80) { 211 skb_put_data(skb, 212 x25->calluserdata.cuddata, 213 x25->calluserdata.cudlength); 214 } 215 x25->calluserdata.cudlength = 0; 216 break; 217 218 case X25_CLEAR_REQUEST: 219 dptr = skb_put(skb, 3); 220 *dptr++ = frametype; 221 *dptr++ = x25->causediag.cause; 222 *dptr++ = x25->causediag.diagnostic; 223 break; 224 225 case X25_RESET_REQUEST: 226 dptr = skb_put(skb, 3); 227 *dptr++ = frametype; 228 *dptr++ = 0x00; /* XXX */ 229 *dptr++ = 0x00; /* XXX */ 230 break; 231 232 case X25_RR: 233 case X25_RNR: 234 case X25_REJ: 235 if (x25->neighbour->extended) { 236 dptr = skb_put(skb, 2); 237 *dptr++ = frametype; 238 *dptr++ = (x25->vr << 1) & 0xFE; 239 } else { 240 dptr = skb_put(skb, 1); 241 *dptr = frametype; 242 *dptr++ |= (x25->vr << 5) & 0xE0; 243 } 244 break; 245 246 case X25_CLEAR_CONFIRMATION: 247 case X25_INTERRUPT_CONFIRMATION: 248 case X25_RESET_CONFIRMATION: 249 dptr = skb_put(skb, 1); 250 *dptr = frametype; 251 break; 252 } 253 254 x25_transmit_link(skb, x25->neighbour); 255 } 256 257 /* 258 * Unpick the contents of the passed X.25 Packet Layer frame. 259 */ 260 int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q, 261 int *d, int *m) 262 { 263 struct x25_sock *x25 = x25_sk(sk); 264 unsigned char *frame; 265 266 if (!pskb_may_pull(skb, X25_STD_MIN_LEN)) 267 return X25_ILLEGAL; 268 frame = skb->data; 269 270 *ns = *nr = *q = *d = *m = 0; 271 272 switch (frame[2]) { 273 case X25_CALL_REQUEST: 274 case X25_CALL_ACCEPTED: 275 case X25_CLEAR_REQUEST: 276 case X25_CLEAR_CONFIRMATION: 277 case X25_INTERRUPT: 278 case X25_INTERRUPT_CONFIRMATION: 279 case X25_RESET_REQUEST: 280 case X25_RESET_CONFIRMATION: 281 case X25_RESTART_REQUEST: 282 case X25_RESTART_CONFIRMATION: 283 case X25_REGISTRATION_REQUEST: 284 case X25_REGISTRATION_CONFIRMATION: 285 case X25_DIAGNOSTIC: 286 return frame[2]; 287 } 288 289 if (x25->neighbour->extended) { 290 if (frame[2] == X25_RR || 291 frame[2] == X25_RNR || 292 frame[2] == X25_REJ) { 293 if (!pskb_may_pull(skb, X25_EXT_MIN_LEN)) 294 return X25_ILLEGAL; 295 frame = skb->data; 296 297 *nr = (frame[3] >> 1) & 0x7F; 298 return frame[2]; 299 } 300 } else { 301 if ((frame[2] & 0x1F) == X25_RR || 302 (frame[2] & 0x1F) == X25_RNR || 303 (frame[2] & 0x1F) == X25_REJ) { 304 *nr = (frame[2] >> 5) & 0x07; 305 return frame[2] & 0x1F; 306 } 307 } 308 309 if (x25->neighbour->extended) { 310 if ((frame[2] & 0x01) == X25_DATA) { 311 if (!pskb_may_pull(skb, X25_EXT_MIN_LEN)) 312 return X25_ILLEGAL; 313 frame = skb->data; 314 315 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT; 316 *d = (frame[0] & X25_D_BIT) == X25_D_BIT; 317 *m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT; 318 *nr = (frame[3] >> 1) & 0x7F; 319 *ns = (frame[2] >> 1) & 0x7F; 320 return X25_DATA; 321 } 322 } else { 323 if ((frame[2] & 0x01) == X25_DATA) { 324 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT; 325 *d = (frame[0] & X25_D_BIT) == X25_D_BIT; 326 *m = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT; 327 *nr = (frame[2] >> 5) & 0x07; 328 *ns = (frame[2] >> 1) & 0x07; 329 return X25_DATA; 330 } 331 } 332 333 pr_debug("invalid PLP frame %3ph\n", frame); 334 335 return X25_ILLEGAL; 336 } 337 338 void x25_disconnect(struct sock *sk, int reason, unsigned char cause, 339 unsigned char diagnostic) 340 { 341 struct x25_sock *x25 = x25_sk(sk); 342 343 x25_clear_queues(sk); 344 x25_stop_timer(sk); 345 346 x25->lci = 0; 347 x25->state = X25_STATE_0; 348 349 x25->causediag.cause = cause; 350 x25->causediag.diagnostic = diagnostic; 351 352 sk->sk_state = TCP_CLOSE; 353 sk->sk_err = reason; 354 sk->sk_shutdown |= SEND_SHUTDOWN; 355 356 if (!sock_flag(sk, SOCK_DEAD)) { 357 sk->sk_state_change(sk); 358 sock_set_flag(sk, SOCK_DEAD); 359 } 360 if (x25->neighbour) { 361 read_lock_bh(&x25_list_lock); 362 x25_neigh_put(x25->neighbour); 363 x25->neighbour = NULL; 364 read_unlock_bh(&x25_list_lock); 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