1 /*- 2 * (MPSAFE) 3 * 4 * ng_tty.c 5 * 6 * Copyright (c) 1996-1999 Whistle Communications, Inc. 7 * All rights reserved. 8 * 9 * Subject to the following obligations and disclaimer of warranty, use and 10 * redistribution of this software, in source or object code forms, with or 11 * without modifications are expressly permitted by Whistle Communications; 12 * provided, however, that: 13 * 1. Any and all reproductions of the source or object code must include the 14 * copyright notice above and the following disclaimer of warranties; and 15 * 2. No rights are granted, in any manner or form, to use Whistle 16 * Communications, Inc. trademarks, including the mark "WHISTLE 17 * COMMUNICATIONS" on advertising, endorsements, or otherwise except as 18 * such appears in the above copyright notice or in the software. 19 * 20 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND 21 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO 22 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, 23 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF 24 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. 25 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY 26 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS 27 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. 28 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES 29 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING 30 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 31 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR 32 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY 36 * OF SUCH DAMAGE. 37 * 38 * Author: Archie Cobbs <archie@freebsd.org> 39 * 40 * $FreeBSD: src/sys/netgraph/ng_tty.c,v 1.37 2006/11/06 13:42:03 rwatson Exp $ 41 * $Whistle: ng_tty.c,v 1.21 1999/11/01 09:24:52 julian Exp $ 42 */ 43 44 /* 45 * This file implements a terminal line discipline that is also a 46 * netgraph node. Installing this line discipline on a terminal device 47 * instantiates a new netgraph node of this type, which allows access 48 * to the device via the "hook" hook of the node. 49 * 50 * Once the line discipline is installed, you can find out the name 51 * of the corresponding netgraph node via a NGIOCGINFO ioctl(). 52 * 53 * Incoming characters are delievered to the hook one at a time, each 54 * in its own mbuf. You may optionally define a ``hotchar,'' which causes 55 * incoming characters to be buffered up until either the hotchar is 56 * seen or the mbuf is full (MHLEN bytes). Then all buffered characters 57 * are immediately delivered. 58 */ 59 60 #include <sys/param.h> 61 #include <sys/systm.h> 62 #include <sys/conf.h> 63 #include <sys/errno.h> 64 #include <sys/fcntl.h> 65 #include <sys/kernel.h> 66 #include <sys/malloc.h> 67 #include <sys/mbuf.h> 68 #include <sys/caps.h> 69 #include <sys/socket.h> 70 #include <sys/syslog.h> 71 #include <sys/tty.h> 72 #include <sys/ttycom.h> 73 74 #include <net/if.h> 75 #include <net/if_var.h> 76 77 #include <netgraph7/netgraph.h> 78 #include <netgraph7/ng_message.h> 79 #include "ng_tty.h" 80 81 /* Misc defs */ 82 #define MAX_MBUFQ 3 /* Max number of queued mbufs */ 83 #define NGT_HIWATER 400 /* High water mark on output */ 84 85 /* Per-node private info */ 86 struct ngt_sc { 87 struct tty *tp; /* Terminal device */ 88 node_p node; /* Netgraph node */ 89 hook_p hook; /* Netgraph hook */ 90 struct ifqueue outq; /* Queue of outgoing data */ 91 struct mbuf *m; /* Incoming data buffer */ 92 short hotchar; /* Hotchar, or -1 if none */ 93 u_int flags; /* Flags */ 94 struct callout chand; /* See man timeout(9) */ 95 }; 96 typedef struct ngt_sc *sc_p; 97 98 /* Flags */ 99 #define FLG_DEBUG 0x0002 100 #define FLG_DIE 0x0004 101 102 /* Line discipline methods */ 103 static int ngt_open(struct cdev *dev, struct tty *tp); 104 static int ngt_close(struct tty *tp, int flag); 105 static int ngt_read(struct tty *tp, struct uio *uio, int flag); 106 static int ngt_write(struct tty *tp, struct uio *uio, int flag); 107 static int ngt_tioctl(struct tty *tp, 108 u_long cmd, caddr_t data, int flag, struct ucred *cred); 109 static int ngt_input(int c, struct tty *tp); 110 static int ngt_start(struct tty *tp); 111 112 /* Netgraph methods */ 113 static ng_constructor_t ngt_constructor; 114 static ng_rcvmsg_t ngt_rcvmsg; 115 static ng_shutdown_t ngt_shutdown; 116 static ng_newhook_t ngt_newhook; 117 static ng_connect_t ngt_connect; 118 static ng_rcvdata_t ngt_rcvdata; 119 static ng_disconnect_t ngt_disconnect; 120 static int ngt_mod_event(module_t mod, int event, void *data); 121 122 /* Other stuff */ 123 static void ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2); 124 125 #define ERROUT(x) do { error = (x); goto done; } while (0) 126 127 /* Line discipline descriptor */ 128 static struct linesw ngt_disc = { 129 .l_open = ngt_open, 130 .l_close = ngt_close, 131 .l_read = ngt_read, 132 .l_write = ngt_write, 133 .l_ioctl = ngt_tioctl, 134 .l_rint = ngt_input, 135 .l_start = ngt_start, 136 .l_modem = ttymodem, 137 }; 138 139 /* Netgraph node type descriptor */ 140 static struct ng_type typestruct = { 141 .version = NG_ABI_VERSION, 142 .name = NG_TTY_NODE_TYPE, 143 .mod_event = ngt_mod_event, 144 .constructor = ngt_constructor, 145 .rcvmsg = ngt_rcvmsg, 146 .shutdown = ngt_shutdown, 147 .newhook = ngt_newhook, 148 .connect = ngt_connect, 149 .rcvdata = ngt_rcvdata, 150 .disconnect = ngt_disconnect, 151 }; 152 NETGRAPH_INIT(tty, &typestruct); 153 154 /* 155 * Locking: 156 * 157 * - node private data and tp->t_lsc is protected by mutex in struct 158 * ifqueue, locking is done using IF_XXX() macros. 159 * - in all tty methods we should acquire node ifqueue mutex, when accessing 160 * private data. 161 * - in _rcvdata() we should use locked versions of IF_{EN,DE}QUEUE() since 162 * we may have multiple _rcvdata() threads. 163 * - when calling any of tty methods from netgraph methods, we should 164 * acquire tty locking (now Giant). 165 * 166 * - ngt_unit is incremented atomically. 167 */ 168 169 static int ngt_unit; 170 static int ngt_ldisc; 171 172 /****************************************************************** 173 LINE DISCIPLINE METHODS 174 ******************************************************************/ 175 176 /* 177 * Set our line discipline on the tty. 178 * Called from device open routine or ttioctl() 179 */ 180 static int 181 ngt_open(struct cdev *dev, struct tty *tp) 182 { 183 char name[sizeof(NG_TTY_NODE_TYPE) + 8]; 184 sc_p sc; 185 int error; 186 187 /* Super-user only */ 188 error = caps_priv_check_self(SYSCAP_NONET_NETGRAPH); 189 if (error) 190 return (error); 191 192 /* Initialize private struct */ 193 sc = kmalloc(sizeof(*sc), M_NETGRAPH, M_WAITOK | M_ZERO); 194 195 lwkt_gettoken(&tp->t_token); 196 sc->tp = tp; 197 sc->hotchar = NG_TTY_DFL_HOTCHAR; 198 sc->outq.ifq_maxlen = MAX_MBUFQ; 199 200 /* Setup netgraph node */ 201 error = ng_make_node_common(&typestruct, &sc->node); 202 if (error) { 203 kfree(sc, M_NETGRAPH); 204 lwkt_reltoken(&tp->t_token); 205 return (error); 206 } 207 208 atomic_add_int(&ngt_unit, 1); 209 ksnprintf(name, sizeof(name), "%s%d", typestruct.name, ngt_unit); 210 211 /* Assign node its name */ 212 if ((error = ng_name_node(sc->node, name))) { 213 sc->flags |= FLG_DIE; 214 NG_NODE_UNREF(sc->node); 215 log(LOG_ERR, "%s: node name exists?\n", name); 216 lwkt_reltoken(&tp->t_token); 217 return (error); 218 } 219 220 /* Set back pointers */ 221 NG_NODE_SET_PRIVATE(sc->node, sc); 222 tp->t_sc = sc; 223 224 callout_init_mp(&sc->chand); 225 226 /* 227 * Pre-allocate cblocks to the an appropriate amount. 228 * I'm not sure what is appropriate. 229 */ 230 ttyflush(tp, FREAD | FWRITE); 231 clist_alloc_cblocks(&tp->t_canq, 0); 232 clist_alloc_cblocks(&tp->t_rawq, 0); 233 clist_alloc_cblocks(&tp->t_outq, MLEN + NGT_HIWATER); 234 235 lwkt_reltoken(&tp->t_token); 236 return (error); 237 } 238 239 /* 240 * Line specific close routine, called from device close routine 241 * and from ttioctl. This causes the node to be destroyed as well. 242 */ 243 static int 244 ngt_close(struct tty *tp, int flag) 245 { 246 const sc_p sc = (sc_p) tp->t_sc; 247 248 lwkt_gettoken(&tp->t_token); 249 ttyflush(tp, FREAD | FWRITE); 250 clist_free_cblocks(&tp->t_outq); 251 if (sc != NULL) { 252 if (callout_pending(&sc->chand)) 253 ng_uncallout(&sc->chand, sc->node); 254 tp->t_sc = NULL; 255 sc->flags |= FLG_DIE; 256 ng_rmnode_self(sc->node); 257 } 258 lwkt_reltoken(&tp->t_token); 259 return (0); 260 } 261 262 /* 263 * Once the device has been turned into a node, we don't allow reading. 264 */ 265 static int 266 ngt_read(struct tty *tp, struct uio *uio, int flag) 267 { 268 return (EIO); 269 } 270 271 /* 272 * Once the device has been turned into a node, we don't allow writing. 273 */ 274 static int 275 ngt_write(struct tty *tp, struct uio *uio, int flag) 276 { 277 return (EIO); 278 } 279 280 /* 281 * We implement the NGIOCGINFO ioctl() defined in ng_message.h. 282 */ 283 static int 284 ngt_tioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct ucred *cred) 285 { 286 const sc_p sc = (sc_p) tp->t_sc; 287 288 if (sc == NULL) { 289 /* No node attached */ 290 return (0); 291 } 292 293 lwkt_gettoken(&tp->t_token); 294 switch (cmd) { 295 case NGIOCGINFO: 296 { 297 struct nodeinfo *const ni = (struct nodeinfo *) data; 298 const node_p node = sc->node; 299 300 bzero(ni, sizeof(*ni)); 301 if (NG_NODE_HAS_NAME(node)) 302 strncpy(ni->name, NG_NODE_NAME(node), sizeof(ni->name) - 1); 303 strncpy(ni->type, node->nd_type->name, sizeof(ni->type) - 1); 304 ni->id = (u_int32_t) ng_node2ID(node); 305 ni->hooks = NG_NODE_NUMHOOKS(node); 306 break; 307 } 308 default: 309 lwkt_reltoken(&tp->t_token); 310 return (ENOIOCTL); 311 } 312 313 lwkt_reltoken(&tp->t_token); 314 return (0); 315 } 316 317 /* 318 * Receive data coming from the device. We get one character at 319 * a time, which is kindof silly. 320 * 321 * Full locking of softc is not required, since we are the only 322 * user of sc->m. 323 */ 324 static int 325 ngt_input(int c, struct tty *tp) 326 { 327 sc_p sc; 328 node_p node; 329 struct mbuf *m; 330 int error = 0; 331 332 lwkt_gettoken(&tp->t_token); 333 sc = (sc_p) tp->t_sc; 334 if (sc == NULL) { 335 /* No node attached */ 336 lwkt_reltoken(&tp->t_token); 337 return (0); 338 } 339 340 node = sc->node; 341 342 if (tp != sc->tp) 343 panic("ngt_input"); 344 345 /* Check for error conditions */ 346 if ((tp->t_state & TS_CONNECTED) == 0) { 347 if (sc->flags & FLG_DEBUG) 348 log(LOG_DEBUG, "%s: no carrier\n", NG_NODE_NAME(node)); 349 lwkt_reltoken(&tp->t_token); 350 return (0); 351 } 352 if (c & TTY_ERRORMASK) { 353 /* framing error or overrun on this char */ 354 if (sc->flags & FLG_DEBUG) 355 log(LOG_DEBUG, "%s: line error %x\n", 356 NG_NODE_NAME(node), c & TTY_ERRORMASK); 357 lwkt_reltoken(&tp->t_token); 358 return (0); 359 } 360 c &= TTY_CHARMASK; 361 362 /* Get a new header mbuf if we need one */ 363 if (!(m = sc->m)) { 364 MGETHDR(m, M_NOWAIT, MT_DATA); 365 if (!m) { 366 if (sc->flags & FLG_DEBUG) 367 log(LOG_ERR, 368 "%s: can't get mbuf\n", NG_NODE_NAME(node)); 369 lwkt_reltoken(&tp->t_token); 370 return (ENOBUFS); 371 } 372 m->m_len = m->m_pkthdr.len = 0; 373 m->m_pkthdr.rcvif = NULL; 374 sc->m = m; 375 } 376 377 /* Add char to mbuf */ 378 *mtod(m, u_char *) = c; 379 m->m_data++; 380 m->m_len++; 381 m->m_pkthdr.len++; 382 383 /* Ship off mbuf if it's time */ 384 if (sc->hotchar == -1 || c == sc->hotchar || m->m_len >= MHLEN) { 385 m->m_data = m->m_pktdat; 386 sc->m = NULL; 387 388 /* 389 * We have built our mbuf without checking that we actually 390 * have a hook to send it. This was done to avoid 391 * acquiring mutex on each character. Check now. 392 * 393 */ 394 395 if (sc->hook == NULL) { 396 m_freem(m); 397 lwkt_reltoken(&tp->t_token); 398 return (0); /* XXX: original behavior */ 399 } 400 NG_SEND_DATA_ONLY(error, sc->hook, m); /* Will queue */ 401 } 402 403 lwkt_reltoken(&tp->t_token); 404 return (error); 405 } 406 407 /* 408 * This is called when the device driver is ready for more output. 409 * Also called from ngt_rcv_data() when a new mbuf is available for output. 410 */ 411 static int 412 ngt_start(struct tty *tp) 413 { 414 const sc_p sc = (sc_p) tp->t_sc; 415 416 lwkt_gettoken(&tp->t_token); 417 while (tp->t_outq.c_cc < NGT_HIWATER) { /* XXX 2.2 specific ? */ 418 struct mbuf *m; 419 420 /* Remove first mbuf from queue */ 421 IF_DEQUEUE(&sc->outq, m); 422 if (m == NULL) 423 break; 424 425 /* Send as much of it as possible */ 426 while (m != NULL) { 427 int sent; 428 429 sent = m->m_len - clist_btoq(mtod(m, u_char *), 430 m->m_len, &tp->t_outq); 431 m->m_data += sent; 432 m->m_len -= sent; 433 if (m->m_len > 0) 434 break; /* device can't take no more */ 435 m = m_free(m); 436 } 437 438 /* Put remainder of mbuf chain (if any) back on queue */ 439 if (m != NULL) { 440 IF_PREPEND(&sc->outq, m); 441 break; 442 } 443 } 444 445 /* Call output process whether or not there is any output. We are 446 * being called in lieu of ttstart and must do what it would. */ 447 if (tp->t_oproc != NULL) 448 (*tp->t_oproc) (tp); 449 450 /* This timeout is needed for operation on a pseudo-tty, because the 451 * pty code doesn't call pppstart after it has drained the t_outq. */ 452 /* XXX: outq not locked */ 453 if (!IF_QEMPTY(&sc->outq) && !callout_pending(&sc->chand)) 454 ng_callout(&sc->chand, sc->node, NULL, 1, ngt_timeout, NULL, 0); 455 456 lwkt_reltoken(&tp->t_token); 457 return (0); 458 } 459 460 /* 461 * We still have data to output to the device, so try sending more. 462 */ 463 static void 464 ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2) 465 { 466 const sc_p sc = NG_NODE_PRIVATE(node); 467 struct tty *tp = sc->tp; 468 469 lwkt_gettoken(&tp->t_token); 470 ngt_start(sc->tp); 471 lwkt_reltoken(&tp->t_token); 472 } 473 474 /****************************************************************** 475 NETGRAPH NODE METHODS 476 ******************************************************************/ 477 478 /* 479 * Initialize a new node of this type. 480 * 481 * We only allow nodes to be created as a result of setting 482 * the line discipline on a tty, so always return an error if not. 483 */ 484 static int 485 ngt_constructor(node_p node) 486 { 487 return (EOPNOTSUPP); 488 } 489 490 /* 491 * Add a new hook. There can only be one. 492 */ 493 static int 494 ngt_newhook(node_p node, hook_p hook, const char *name) 495 { 496 const sc_p sc = NG_NODE_PRIVATE(node); 497 struct tty *tp = sc->tp; 498 499 if (strcmp(name, NG_TTY_HOOK)) 500 return (EINVAL); 501 lwkt_gettoken(&tp->t_token); 502 if (sc->hook) { 503 lwkt_reltoken(&tp->t_token); 504 return (EISCONN); 505 } 506 sc->hook = hook; 507 lwkt_reltoken(&tp->t_token); 508 return (0); 509 } 510 511 /* 512 * Set the hook into queueing mode (for outgoing packets), 513 * so that we wont deliver mbuf thru the whole graph holding 514 * tty locks. 515 */ 516 static int 517 ngt_connect(hook_p hook) 518 { 519 NG_HOOK_FORCE_QUEUE(NG_HOOK_PEER(hook)); 520 /* 521 * XXX: While ngt_start() is Giant-locked, queue incoming 522 * packets, too. Otherwise we acquire Giant holding some 523 * IP stack locks, e.g. divinp, and this makes WITNESS scream. 524 */ 525 NG_HOOK_FORCE_QUEUE(hook); 526 return (0); 527 } 528 529 /* 530 * Disconnect the hook 531 */ 532 static int 533 ngt_disconnect(hook_p hook) 534 { 535 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook)); 536 struct tty *tp = sc->tp; 537 538 lwkt_gettoken(&tp->t_token); 539 if (hook != sc->hook) 540 panic(__func__); 541 sc->hook = NULL; 542 lwkt_reltoken(&tp->t_token); 543 return (0); 544 } 545 546 /* 547 * Remove this node. The does the netgraph portion of the shutdown. 548 * This should only be called indirectly from ngt_close(). 549 * 550 * tp->t_lsc is already NULL, so we should be protected from 551 * tty calls now. 552 */ 553 static int 554 ngt_shutdown(node_p node) 555 { 556 const sc_p sc = NG_NODE_PRIVATE(node); 557 struct tty *tp = sc->tp; 558 559 lwkt_gettoken(&tp->t_token); 560 if (!(sc->flags & FLG_DIE)) { 561 lwkt_reltoken(&tp->t_token); 562 return (EOPNOTSUPP); 563 } 564 565 /* Free resources */ 566 IF_DRAIN(&sc->outq); 567 m_freem(sc->m); 568 kfree(sc, M_NETGRAPH); 569 lwkt_reltoken(&tp->t_token); 570 return (0); 571 } 572 573 /* 574 * Receive incoming data from netgraph system. Put it on our 575 * output queue and start output if necessary. 576 */ 577 static int 578 ngt_rcvdata(hook_p hook, item_p item) 579 { 580 const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook)); 581 struct tty *tp = sc->tp; 582 struct mbuf *m; 583 int qlen; 584 585 if (hook != sc->hook) 586 panic(__func__); 587 588 NGI_GET_M(item, m); 589 NG_FREE_ITEM(item); 590 591 if (IF_QFULL(&sc->outq)) { 592 IF_DROP(&sc->outq); 593 NG_FREE_M(m); 594 return (ENOBUFS); 595 } 596 597 IF_ENQUEUE(&sc->outq, m); 598 qlen = sc->outq.ifq_len; 599 600 /* 601 * If qlen > 1, then we should already have a scheduled callout. 602 */ 603 if (qlen == 1) { 604 lwkt_gettoken(&tp->t_token); 605 ngt_start(sc->tp); 606 lwkt_reltoken(&tp->t_token); 607 } 608 609 return (0); 610 } 611 612 /* 613 * Receive control message 614 */ 615 static int 616 ngt_rcvmsg(node_p node, item_p item, hook_p lasthook) 617 { 618 const sc_p sc = NG_NODE_PRIVATE(node); 619 struct ng_mesg *msg, *resp = NULL; 620 int error = 0; 621 622 NGI_GET_MSG(item, msg); 623 switch (msg->header.typecookie) { 624 case NGM_TTY_COOKIE: 625 switch (msg->header.cmd) { 626 case NGM_TTY_SET_HOTCHAR: 627 { 628 int hotchar; 629 630 if (msg->header.arglen != sizeof(int)) 631 ERROUT(EINVAL); 632 hotchar = *((int *) msg->data); 633 if (hotchar != (u_char) hotchar && hotchar != -1) 634 ERROUT(EINVAL); 635 sc->hotchar = hotchar; /* race condition is OK */ 636 break; 637 } 638 case NGM_TTY_GET_HOTCHAR: 639 NG_MKRESPONSE(resp, msg, sizeof(int), M_WAITOK | M_NULLOK); 640 if (!resp) 641 ERROUT(ENOMEM); 642 /* Race condition here is OK */ 643 *((int *) resp->data) = sc->hotchar; 644 break; 645 default: 646 ERROUT(EINVAL); 647 } 648 break; 649 default: 650 ERROUT(EINVAL); 651 } 652 done: 653 NG_RESPOND_MSG(error, node, item, resp); 654 NG_FREE_MSG(msg); 655 return (error); 656 } 657 658 /****************************************************************** 659 INITIALIZATION 660 ******************************************************************/ 661 662 /* 663 * Handle loading and unloading for this node type 664 */ 665 static int 666 ngt_mod_event(module_t mod, int event, void *data) 667 { 668 int error = 0; 669 670 switch (event) { 671 case MOD_LOAD: 672 /* Register line discipline */ 673 if ((ngt_ldisc = ldisc_register(NETGRAPHDISC, &ngt_disc)) < 0) { 674 log(LOG_ERR, "%s: can't register line discipline", 675 __func__); 676 return (EIO); 677 } 678 break; 679 680 case MOD_UNLOAD: 681 682 /* Unregister line discipline */ 683 ldisc_deregister(ngt_ldisc); 684 break; 685 686 default: 687 error = EOPNOTSUPP; 688 break; 689 } 690 return (error); 691 } 692