1 /* 2 * xenstore_dev.c 3 * 4 * Driver giving user-space access to the kernel's connection to the 5 * XenStore service. 6 * 7 * Copyright (c) 2005, Christian Limpach 8 * Copyright (c) 2005, Rusty Russell, IBM Corporation 9 * 10 * This file may be distributed separately from the Linux kernel, or 11 * incorporated into other software packages, subject to the following license: 12 * 13 * Permission is hereby granted, free of charge, to any person obtaining a copy 14 * of this source file (the "Software"), to deal in the Software without 15 * restriction, including without limitation the rights to use, copy, modify, 16 * merge, publish, distribute, sublicense, and/or sell copies of the Software, 17 * and to permit persons to whom the Software is furnished to do so, subject to 18 * the following conditions: 19 * 20 * The above copyright notice and this permission notice shall be included in 21 * all copies or substantial portions of the Software. 22 * 23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 24 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 25 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 26 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 27 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 28 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 29 * IN THE SOFTWARE. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include <sys/types.h> 36 #include <sys/cdefs.h> 37 #include <sys/errno.h> 38 #include <sys/uio.h> 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/proc.h> 42 #include <sys/kernel.h> 43 #include <sys/malloc.h> 44 #include <sys/conf.h> 45 #include <sys/module.h> 46 #include <sys/selinfo.h> 47 #include <sys/sysctl.h> 48 #include <sys/poll.h> 49 50 #include <xen/xen-os.h> 51 52 #include <xen/hypervisor.h> 53 #include <xen/xenstore/xenstorevar.h> 54 #include <xen/xenstore/xenstore_internal.h> 55 56 static unsigned int max_pending_watches = 1000; 57 58 struct xs_dev_transaction { 59 LIST_ENTRY(xs_dev_transaction) list; 60 struct xs_transaction handle; 61 }; 62 63 struct xs_dev_watch { 64 LIST_ENTRY(xs_dev_watch) list; 65 struct xs_watch watch; 66 char *token; 67 struct xs_dev_data *user; 68 }; 69 70 struct xs_dev_data { 71 /* In-progress transaction. */ 72 LIST_HEAD(, xs_dev_transaction) transactions; 73 74 /* Active watches. */ 75 LIST_HEAD(, xs_dev_watch) watches; 76 77 /* Partial request. */ 78 unsigned int len; 79 union { 80 struct xsd_sockmsg msg; 81 char buffer[PAGE_SIZE]; 82 } u; 83 84 /* Response queue. */ 85 #define MASK_READ_IDX(idx) ((idx)&(PAGE_SIZE-1)) 86 char read_buffer[PAGE_SIZE]; 87 unsigned int read_cons, read_prod; 88 89 /* Serializes writes to the read buffer. */ 90 struct mtx lock; 91 92 /* Polling structure (for reads only ATM). */ 93 struct selinfo ev_rsel; 94 }; 95 96 static void 97 xs_queue_reply(struct xs_dev_data *u, const char *data, unsigned int len) 98 { 99 unsigned int i; 100 101 for (i = 0; i < len; i++, u->read_prod++) 102 u->read_buffer[MASK_READ_IDX(u->read_prod)] = data[i]; 103 104 KASSERT((u->read_prod - u->read_cons) <= sizeof(u->read_buffer), 105 ("xenstore reply too big")); 106 107 wakeup(u); 108 selwakeup(&u->ev_rsel); 109 } 110 111 static const char * 112 xs_dev_error_to_string(int error) 113 { 114 unsigned int i; 115 116 for (i = 0; i < nitems(xsd_errors); i++) 117 if (xsd_errors[i].errnum == error) 118 return (xsd_errors[i].errstring); 119 120 return (NULL); 121 } 122 123 static void 124 xs_dev_return_error(struct xs_dev_data *u, int error, int req_id, int tx_id) 125 { 126 struct xsd_sockmsg msg; 127 const char *payload; 128 129 msg.type = XS_ERROR; 130 msg.req_id = req_id; 131 msg.tx_id = tx_id; 132 payload = NULL; 133 134 payload = xs_dev_error_to_string(error); 135 if (payload == NULL) 136 payload = xs_dev_error_to_string(EINVAL); 137 KASSERT(payload != NULL, ("Unable to find string for EINVAL errno")); 138 139 msg.len = strlen(payload) + 1; 140 141 mtx_lock(&u->lock); 142 xs_queue_reply(u, (char *)&msg, sizeof(msg)); 143 xs_queue_reply(u, payload, msg.len); 144 mtx_unlock(&u->lock); 145 } 146 147 static int 148 xs_dev_watch_message_parse_string(const char **p, const char *end, 149 const char **string_r) 150 { 151 const char *nul; 152 153 nul = memchr(*p, 0, end - *p); 154 if (!nul) 155 return (EINVAL); 156 157 *string_r = *p; 158 *p = nul+1; 159 160 return (0); 161 } 162 163 static int 164 xs_dev_watch_message_parse(const struct xsd_sockmsg *msg, const char **path_r, 165 const char **token_r) 166 { 167 const char *p, *end; 168 int error; 169 170 p = (const char *)msg + sizeof(*msg); 171 end = p + msg->len; 172 KASSERT(p <= end, ("payload overflow")); 173 174 error = xs_dev_watch_message_parse_string(&p, end, path_r); 175 if (error) 176 return (error); 177 error = xs_dev_watch_message_parse_string(&p, end, token_r); 178 if (error) 179 return (error); 180 181 return (0); 182 } 183 184 static struct xs_dev_watch * 185 xs_dev_find_watch(struct xs_dev_data *u, const char *token) 186 { 187 struct xs_dev_watch *watch; 188 189 LIST_FOREACH(watch, &u->watches, list) 190 if (strcmp(watch->token, token) == 0) 191 return (watch); 192 193 return (NULL); 194 } 195 196 static void 197 xs_dev_watch_cb(struct xs_watch *watch, const char **vec, unsigned int len) 198 { 199 struct xs_dev_watch *dwatch; 200 struct xsd_sockmsg msg; 201 char *payload; 202 203 dwatch = (struct xs_dev_watch *)watch->callback_data; 204 msg.type = XS_WATCH_EVENT; 205 msg.req_id = msg.tx_id = 0; 206 msg.len = strlen(vec[XS_WATCH_PATH]) + strlen(dwatch->token) + 2; 207 208 payload = malloc(msg.len, M_XENSTORE, M_WAITOK); 209 strcpy(payload, vec[XS_WATCH_PATH]); 210 strcpy(&payload[strlen(vec[XS_WATCH_PATH]) + 1], dwatch->token); 211 mtx_lock(&dwatch->user->lock); 212 xs_queue_reply(dwatch->user, (char *)&msg, sizeof(msg)); 213 xs_queue_reply(dwatch->user, payload, msg.len); 214 mtx_unlock(&dwatch->user->lock); 215 free(payload, M_XENSTORE); 216 } 217 218 static struct xs_dev_transaction * 219 xs_dev_find_transaction(struct xs_dev_data *u, uint32_t tx_id) 220 { 221 struct xs_dev_transaction *trans; 222 223 LIST_FOREACH(trans, &u->transactions, list) 224 if (trans->handle.id == tx_id) 225 return (trans); 226 227 return (NULL); 228 } 229 230 static int 231 xs_dev_read(struct cdev *dev, struct uio *uio, int ioflag) 232 { 233 int error; 234 struct xs_dev_data *u; 235 236 error = devfs_get_cdevpriv((void **)&u); 237 if (error != 0) 238 return (error); 239 240 while (u->read_prod == u->read_cons) { 241 error = tsleep(u, PCATCH, "xsdread", hz/10); 242 if (error && error != EWOULDBLOCK) 243 return (error); 244 } 245 246 while (uio->uio_resid > 0) { 247 if (u->read_cons == u->read_prod) 248 break; 249 error = uiomove(&u->read_buffer[MASK_READ_IDX(u->read_cons)], 250 1, uio); 251 if (error) 252 return (error); 253 u->read_cons++; 254 } 255 return (0); 256 } 257 258 static int 259 xs_dev_write(struct cdev *dev, struct uio *uio, int ioflag) 260 { 261 int error; 262 const char *wpath, *wtoken; 263 struct xs_dev_data *u; 264 struct xs_dev_transaction *trans; 265 struct xs_dev_watch *watch; 266 void *reply; 267 static const char *ok = "OK"; 268 int len = uio->uio_resid; 269 270 error = devfs_get_cdevpriv((void **)&u); 271 if (error != 0) 272 return (error); 273 274 if ((len + u->len) > sizeof(u->u.buffer)) 275 return (EINVAL); 276 277 error = uiomove(u->u.buffer + u->len, len, uio); 278 if (error) 279 return (error); 280 281 u->len += len; 282 if (u->len < (sizeof(u->u.msg) + u->u.msg.len)) 283 return (0); 284 285 switch (u->u.msg.type) { 286 case XS_TRANSACTION_START: 287 case XS_TRANSACTION_END: 288 case XS_DIRECTORY: 289 case XS_READ: 290 case XS_GET_PERMS: 291 case XS_RELEASE: 292 case XS_GET_DOMAIN_PATH: 293 case XS_WRITE: 294 case XS_MKDIR: 295 case XS_RM: 296 case XS_SET_PERMS: 297 /* Check that this transaction id is not hijacked. */ 298 if (u->u.msg.tx_id != 0 && 299 xs_dev_find_transaction(u, u->u.msg.tx_id) == NULL) { 300 error = EINVAL; 301 break; 302 } 303 error = xs_dev_request_and_reply(&u->u.msg, &reply); 304 if (!error) { 305 if (u->u.msg.type == XS_TRANSACTION_START) { 306 trans = malloc(sizeof(*trans), M_XENSTORE, 307 M_WAITOK); 308 trans->handle.id = strtoul(reply, NULL, 0); 309 LIST_INSERT_HEAD(&u->transactions, trans, list); 310 } else if (u->u.msg.type == XS_TRANSACTION_END) { 311 trans = xs_dev_find_transaction(u, 312 u->u.msg.tx_id); 313 KASSERT(trans != NULL, 314 ("Unable to find transaction")); 315 LIST_REMOVE(trans, list); 316 free(trans, M_XENSTORE); 317 } 318 mtx_lock(&u->lock); 319 xs_queue_reply(u, (char *)&u->u.msg, sizeof(u->u.msg)); 320 xs_queue_reply(u, (char *)reply, u->u.msg.len); 321 mtx_unlock(&u->lock); 322 free(reply, M_XENSTORE); 323 } 324 break; 325 case XS_WATCH: 326 u->u.msg.tx_id = 0; 327 error = xs_dev_watch_message_parse(&u->u.msg, &wpath, &wtoken); 328 if (error) 329 break; 330 if (xs_dev_find_watch(u, wtoken) != NULL) { 331 error = EINVAL; 332 break; 333 } 334 335 watch = malloc(sizeof(*watch), M_XENSTORE, M_WAITOK); 336 watch->watch.node = strdup(wpath, M_XENSTORE); 337 watch->watch.callback = xs_dev_watch_cb; 338 watch->watch.callback_data = (uintptr_t)watch; 339 watch->watch.max_pending = max_pending_watches; 340 watch->token = strdup(wtoken, M_XENSTORE); 341 watch->user = u; 342 343 error = xs_register_watch(&watch->watch); 344 if (error != 0) { 345 free(watch->token, M_XENSTORE); 346 free(watch->watch.node, M_XENSTORE); 347 free(watch, M_XENSTORE); 348 break; 349 } 350 351 LIST_INSERT_HEAD(&u->watches, watch, list); 352 u->u.msg.len = sizeof(ok); 353 mtx_lock(&u->lock); 354 xs_queue_reply(u, (char *)&u->u.msg, sizeof(u->u.msg)); 355 xs_queue_reply(u, ok, sizeof(ok)); 356 mtx_unlock(&u->lock); 357 break; 358 case XS_UNWATCH: 359 u->u.msg.tx_id = 0; 360 error = xs_dev_watch_message_parse(&u->u.msg, &wpath, &wtoken); 361 if (error) 362 break; 363 watch = xs_dev_find_watch(u, wtoken); 364 if (watch == NULL) { 365 error = EINVAL; 366 break; 367 } 368 369 LIST_REMOVE(watch, list); 370 xs_unregister_watch(&watch->watch); 371 free(watch->watch.node, M_XENSTORE); 372 free(watch->token, M_XENSTORE); 373 free(watch, M_XENSTORE); 374 u->u.msg.len = sizeof(ok); 375 mtx_lock(&u->lock); 376 xs_queue_reply(u, (char *)&u->u.msg, sizeof(u->u.msg)); 377 xs_queue_reply(u, ok, sizeof(ok)); 378 mtx_unlock(&u->lock); 379 break; 380 default: 381 error = EINVAL; 382 break; 383 } 384 385 if (error != 0) 386 xs_dev_return_error(u, error, u->u.msg.req_id, u->u.msg.tx_id); 387 388 /* Reset the write buffer. */ 389 u->len = 0; 390 391 return (0); 392 } 393 394 static int 395 xs_dev_poll(struct cdev *dev, int events, struct thread *td) 396 { 397 struct xs_dev_data *u; 398 int error, mask; 399 400 error = devfs_get_cdevpriv((void **)&u); 401 if (error != 0) 402 return (POLLERR); 403 404 /* we can always write */ 405 mask = events & (POLLOUT | POLLWRNORM); 406 407 if (events & (POLLIN | POLLRDNORM)) { 408 if (u->read_cons != u->read_prod) { 409 mask |= events & (POLLIN | POLLRDNORM); 410 } else { 411 /* Record that someone is waiting */ 412 selrecord(td, &u->ev_rsel); 413 } 414 } 415 416 return (mask); 417 } 418 419 static void 420 xs_dev_dtor(void *arg) 421 { 422 struct xs_dev_data *u = arg; 423 struct xs_dev_transaction *trans, *tmpt; 424 struct xs_dev_watch *watch, *tmpw; 425 426 seldrain(&u->ev_rsel); 427 428 LIST_FOREACH_SAFE(trans, &u->transactions, list, tmpt) { 429 xs_transaction_end(trans->handle, 1); 430 LIST_REMOVE(trans, list); 431 free(trans, M_XENSTORE); 432 } 433 434 LIST_FOREACH_SAFE(watch, &u->watches, list, tmpw) { 435 LIST_REMOVE(watch, list); 436 xs_unregister_watch(&watch->watch); 437 free(watch->watch.node, M_XENSTORE); 438 free(watch->token, M_XENSTORE); 439 free(watch, M_XENSTORE); 440 } 441 mtx_destroy(&u->lock); 442 443 free(u, M_XENSTORE); 444 } 445 446 static int 447 xs_dev_open(struct cdev *dev, int oflags, int devtype, struct thread *td) 448 { 449 struct xs_dev_data *u; 450 int error; 451 452 u = malloc(sizeof(*u), M_XENSTORE, M_WAITOK|M_ZERO); 453 mtx_init(&u->lock, "xsdev_lock", NULL, MTX_DEF); 454 LIST_INIT(&u->transactions); 455 LIST_INIT(&u->watches); 456 error = devfs_set_cdevpriv(u, xs_dev_dtor); 457 if (error != 0) 458 free(u, M_XENSTORE); 459 460 return (error); 461 } 462 463 static struct cdevsw xs_dev_cdevsw = { 464 .d_version = D_VERSION, 465 .d_read = xs_dev_read, 466 .d_write = xs_dev_write, 467 .d_open = xs_dev_open, 468 .d_poll = xs_dev_poll, 469 .d_name = "xs_dev", 470 }; 471 472 /*------------------ Private Device Attachment Functions --------------------*/ 473 /** 474 * \brief Identify instances of this device type in the system. 475 * 476 * \param driver The driver performing this identify action. 477 * \param parent The NewBus parent device for any devices this method adds. 478 */ 479 static void 480 xs_dev_identify(driver_t *driver __unused, device_t parent) 481 { 482 /* 483 * A single device instance for our driver is always present 484 * in a system operating under Xen. 485 */ 486 BUS_ADD_CHILD(parent, 0, driver->name, 0); 487 } 488 489 /** 490 * \brief Probe for the existence of the Xenstore device 491 * 492 * \param dev NewBus device_t for this instance. 493 * 494 * \return Always returns 0 indicating success. 495 */ 496 static int 497 xs_dev_probe(device_t dev) 498 { 499 500 device_set_desc(dev, "Xenstore user-space device"); 501 return (0); 502 } 503 504 /** 505 * \brief Attach the Xenstore device. 506 * 507 * \param dev NewBus device_t for this instance. 508 * 509 * \return On success, 0. Otherwise an errno value indicating the 510 * type of failure. 511 */ 512 static int 513 xs_dev_attach(device_t dev) 514 { 515 struct cdev *xs_cdev; 516 struct sysctl_ctx_list *sysctl_ctx; 517 struct sysctl_oid *sysctl_tree; 518 519 sysctl_ctx = device_get_sysctl_ctx(dev); 520 sysctl_tree = device_get_sysctl_tree(dev); 521 if (sysctl_ctx == NULL || sysctl_tree == NULL) 522 return (EINVAL); 523 524 SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO, 525 "max_pending_watch_events", CTLFLAG_RW, &max_pending_watches, 0, 526 "maximum amount of pending watch events to be delivered"); 527 528 xs_cdev = make_dev_credf(MAKEDEV_ETERNAL, &xs_dev_cdevsw, 0, NULL, 529 UID_ROOT, GID_WHEEL, 0400, "xen/xenstore"); 530 if (xs_cdev == NULL) 531 return (EINVAL); 532 533 return (0); 534 } 535 536 /*-------------------- Private Device Attachment Data -----------------------*/ 537 static device_method_t xs_dev_methods[] = { 538 /* Device interface */ 539 DEVMETHOD(device_identify, xs_dev_identify), 540 DEVMETHOD(device_probe, xs_dev_probe), 541 DEVMETHOD(device_attach, xs_dev_attach), 542 543 DEVMETHOD_END 544 }; 545 546 DEFINE_CLASS_0(xs_dev, xs_dev_driver, xs_dev_methods, 0); 547 devclass_t xs_dev_devclass; 548 549 DRIVER_MODULE(xs_dev, xenstore, xs_dev_driver, xs_dev_devclass, 550 NULL, NULL); 551