drivers/xen/xenbus/xenbus_dev.c

   1 /*
   2  * xenbus_dev.c
   3  *
   4  * Driver giving user-space access to the kernel's xenbus connection
   5  * to xenstore.
   6  *
   7  * Copyright (c) 2005, Christian Limpach
   8  * Copyright (c) 2005, Rusty Russell, IBM Corporation
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License version 2
  12  * as published by the Free Software Foundation; or, when distributed
  13  * separately from the Linux kernel or incorporated into other
  14  * software packages, subject to the following license:
  15  *
  16  * Permission is hereby granted, free of charge, to any person obtaining a copy
  17  * of this source file (the "Software"), to deal in the Software without
  18  * restriction, including without limitation the rights to use, copy, modify,
  19  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  20  * and to permit persons to whom the Software is furnished to do so, subject to
  21  * the following conditions:
  22  *
  23  * The above copyright notice and this permission notice shall be included in
  24  * all copies or substantial portions of the Software.
  25  *
  26  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  27  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  28  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  29  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  30  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  31  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  32  * IN THE SOFTWARE.
  33  */
  34
  35 #include <linux/kernel.h>
  36 #include <linux/slab.h>
  37 #include <linux/errno.h>
  38 #include <linux/uio.h>
  39 #include <linux/notifier.h>
  40 #include <linux/sched.h>
  41 #include <linux/wait.h>
  42 #include <linux/fs.h>
  43 #include <linux/poll.h>
  44 #include <linux/mutex.h>
  45
  46 #include "xenbus_comms.h"
  47
  48 #include <asm/uaccess.h>
  49 #include <asm/hypervisor.h>
  50 #include <xen/xenbus.h>
  51 #include <xen/xen_proc.h>
  52 #include <asm/hypervisor.h>
  53
  54 #ifdef HAVE_XEN_PLATFORM_COMPAT_H
  55 #include <xen/platform-compat.h>
  56 #endif
  57
  58 #include <xen/public/xenbus.h>
  59
  60 struct xenbus_dev_transaction {
  61         struct list_head list;
  62         struct xenbus_transaction handle;
  63 };
  64
  65 struct read_buffer {
  66         struct list_head list;
  67         unsigned int cons;
  68         unsigned int len;
  69         char msg[];
  70 };
  71
  72 struct xenbus_dev_data {
  73         /* In-progress transaction. */
  74         struct list_head transactions;
  75
  76         /* Active watches. */
  77         struct list_head watches;
  78
  79         /* Partial request. */
  80         unsigned int len;
  81         union {
  82                 struct xsd_sockmsg msg;
  83                 char buffer[XENSTORE_PAYLOAD_MAX];
  84         } u;
  85
  86         /* Response queue. */
  87         struct list_head read_buffers;
  88         wait_queue_head_t read_waitq;
  89
  90         struct mutex reply_mutex;
  91 };
  92
  93 static struct proc_dir_entry *xenbus_dev_intf;
  94
  95 static ssize_t xenbus_dev_read(struct file *filp,
  96                                char __user *ubuf,
  97                                size_t len, loff_t *ppos)
  98 {
  99         struct xenbus_dev_data *u = filp->private_data;
 100         struct read_buffer *rb;
 101         int i, ret;
 102
 103         if (!is_xenstored_ready())
 104                 return -ENODEV;
 105
 106         mutex_lock(&u->reply_mutex);
 107         while (list_empty(&u->read_buffers)) {
 108                 mutex_unlock(&u->reply_mutex);
 109                 if (filp->f_flags & O_NONBLOCK)
 110                         return -EAGAIN;
 111
 112                 ret = wait_event_interruptible(u->read_waitq,
 113                                                !list_empty(&u->read_buffers));
 114                 if (ret)
 115                         return ret;
 116                 mutex_lock(&u->reply_mutex);
 117         }
 118
 119         rb = list_entry(u->read_buffers.next, struct read_buffer, list);
 120         for (i = 0; i < len;) {
 121                 put_user(rb->msg[rb->cons], ubuf + i);
 122                 i++;
 123                 rb->cons++;
 124                 if (rb->cons == rb->len) {
 125                         list_del(&rb->list);
 126                         kfree(rb);
 127                         if (list_empty(&u->read_buffers))
 128                                 break;
 129                         rb = list_entry(u->read_buffers.next,
 130                                         struct read_buffer, list);
 131                 }
 132         }
 133         mutex_unlock(&u->reply_mutex);
 134
 135         return i;
 136 }
 137
 138 static int queue_reply(struct list_head *queue,
 139                        const void *data, unsigned int len)
 140 {
 141         struct read_buffer *rb;
 142
 143         if (len == 0)
 144                 return 0;
 145
 146         rb = kmalloc(sizeof(*rb) + len, GFP_KERNEL);
 147         if (!rb)
 148                 return -ENOMEM;
 149
 150         rb->cons = 0;
 151         rb->len = len;
 152
 153         memcpy(rb->msg, data, len);
 154
 155         list_add_tail(&rb->list, queue);
 156         return 0;
 157 }
 158
 159 static void queue_flush(struct xenbus_dev_data *u, struct list_head *queue,
 160                         int err)
 161 {
 162         if (!err) {
 163                 list_splice_tail(queue, &u->read_buffers);
 164                 wake_up(&u->read_waitq);
 165         } else
 166                 while (!list_empty(queue)) {
 167                         struct read_buffer *rb = list_entry(queue->next,
 168                                 struct read_buffer, list);
 169
 170                         list_del(queue->next);
 171                         kfree(rb);
 172                 }
 173 }
 174
 175 struct watch_adapter
 176 {
 177         struct list_head list;
 178         struct xenbus_watch watch;
 179         struct xenbus_dev_data *dev_data;
 180         char *token;
 181 };
 182
 183 static void free_watch_adapter (struct watch_adapter *watch)
 184 {
 185         kfree(watch->watch.node);
 186         kfree(watch->token);
 187         kfree(watch);
 188 }
 189
 190 static void watch_fired(struct xenbus_watch *watch,
 191                         const char **vec,
 192                         unsigned int len)
 193 {
 194         struct watch_adapter *adap =
 195             container_of(watch, struct watch_adapter, watch);
 196         struct xsd_sockmsg hdr;
 197         const char *path, *token;
 198         int err, path_len, tok_len, body_len, data_len = 0;
 199         LIST_HEAD(queue);
 200
 201         path = vec[XS_WATCH_PATH];
 202         token = adap->token;
 203
 204         path_len = strlen(path) + 1;
 205         tok_len = strlen(token) + 1;
 206         if (len > 2)
 207                 data_len = vec[len] - vec[2] + 1;
 208         body_len = path_len + tok_len + data_len;
 209
 210         hdr.type = XS_WATCH_EVENT;
 211         hdr.len = body_len;
 212
 213         mutex_lock(&adap->dev_data->reply_mutex);
 214         err = queue_reply(&queue, &hdr, sizeof(hdr));
 215         if (!err)
 216                 err = queue_reply(&queue, path, path_len);
 217         if (!err)
 218                 err = queue_reply(&queue, token, tok_len);
 219         if (!err && len > 2)
 220                 err = queue_reply(&queue, vec[2], data_len);
 221         queue_flush(adap->dev_data, &queue, err);
 222         mutex_unlock(&adap->dev_data->reply_mutex);
 223 }
 224
 225 static LIST_HEAD(watch_list);
 226
 227 static ssize_t xenbus_dev_write(struct file *filp,
 228                                 const char __user *ubuf,
 229                                 size_t len, loff_t *ppos)
 230 {
 231         struct xenbus_dev_data *u = filp->private_data;
 232         struct xenbus_dev_transaction *trans = NULL;
 233         uint32_t msg_type;
 234         void *reply = NULL;
 235         LIST_HEAD(queue);
 236         char *path, *token;
 237         struct watch_adapter *watch;
 238         int err, rc = len;
 239
 240         if (!is_xenstored_ready())
 241                 return -ENODEV;
 242
 243         if ((len + u->len) > sizeof(u->u.buffer)) {
 244                 rc = -EINVAL;
 245                 goto out;
 246         }
 247
 248         if (copy_from_user(u->u.buffer + u->len, ubuf, len) != 0) {
 249                 rc = -EFAULT;
 250                 goto out;
 251         }
 252
 253         u->len += len;
 254         if ((u->len < sizeof(u->u.msg)) ||
 255             (u->len < (sizeof(u->u.msg) + u->u.msg.len)))
 256                 return rc;
 257
 258         msg_type = u->u.msg.type;
 259
 260         switch (msg_type) {
 261         case XS_WATCH:
 262         case XS_UNWATCH: {
 263                 static const char XS_RESP[] = "OK";
 264                 struct xsd_sockmsg hdr;
 265
 266                 path = u->u.buffer + sizeof(u->u.msg);
 267                 token = memchr(path, 0, u->u.msg.len);
 268                 if (token == NULL) {
 269                         rc = -EILSEQ;
 270                         goto out;
 271                 }
 272                 token++;
 273                 if (memchr(token, 0, u->u.msg.len - (token - path)) == NULL) {
 274                         rc = -EILSEQ;
 275                         goto out;
 276                 }
 277
 278                 if (msg_type == XS_WATCH) {
 279                         watch = kzalloc(sizeof(*watch), GFP_KERNEL);
 280                         if (watch == NULL) {
 281                                 rc = -ENOMEM;
 282                                 goto out;
 283                         }
 284                         watch->watch.node = kstrdup(path, GFP_KERNEL);
 285                         watch->watch.callback = watch_fired;
 286                         watch->token = kstrdup(token, GFP_KERNEL);
 287                         watch->dev_data = u;
 288
 289                         err = watch->watch.node && watch->token
 290                               ? register_xenbus_watch(&watch->watch) : -ENOMEM;
 291                         if (err) {
 292                                 free_watch_adapter(watch);
 293                                 rc = err;
 294                                 goto out;
 295                         }
 296
 297                         list_add(&watch->list, &u->watches);
 298                 } else {
 299                         list_for_each_entry(watch, &u->watches, list) {
 300                                 if (!strcmp(watch->token, token) &&
 301                                     !strcmp(watch->watch.node, path))
 302                                 {
 303                                         unregister_xenbus_watch(&watch->watch);
 304                                         list_del(&watch->list);
 305                                         free_watch_adapter(watch);
 306                                         break;
 307                                 }
 308                         }
 309                 }
 310
 311                 hdr.type = msg_type;
 312                 hdr.len = sizeof(XS_RESP);
 313                 mutex_lock(&u->reply_mutex);
 314                 err = queue_reply(&queue, &hdr, sizeof(hdr))
 315                       ?: queue_reply(&queue, XS_RESP, hdr.len);
 316                 break;
 317         }
 318
 319         case XS_TRANSACTION_START:
 320                 trans = kmalloc(sizeof(*trans), GFP_KERNEL);
 321                 if (!trans) {
 322                         rc = -ENOMEM;
 323                         goto out;
 324                 }
 325                 goto common;
 326
 327         case XS_TRANSACTION_END:
 328                 list_for_each_entry(trans, &u->transactions, list)
 329                         if (trans->handle.id == u->u.msg.tx_id)
 330                                 break;
 331                 if (&trans->list == &u->transactions) {
 332                         rc = -ESRCH;
 333                         goto out;
 334                 }
 335                 /* fall through */
 336         common:
 337         default:
 338                 reply = xenbus_dev_request_and_reply(&u->u.msg);
 339                 if (IS_ERR(reply)) {
 340                         if (msg_type == XS_TRANSACTION_START)
 341                                 kfree(trans);
 342                         rc = PTR_ERR(reply);
 343                         goto out;
 344                 }
 345
 346                 if (msg_type == XS_TRANSACTION_START) {
 347                         trans->handle.id = simple_strtoul(reply, NULL, 0);
 348                         list_add(&trans->list, &u->transactions);
 349                 } else if (msg_type == XS_TRANSACTION_END) {
 350                         list_del(&trans->list);
 351                         kfree(trans);
 352                 }
 353                 mutex_lock(&u->reply_mutex);
 354                 err = queue_reply(&queue, &u->u.msg, sizeof(u->u.msg))
 355                       ?: queue_reply(&queue, reply, u->u.msg.len);
 356                 break;
 357         }
 358
 359         queue_flush(u, &queue, err);
 360         mutex_unlock(&u->reply_mutex);
 361         kfree(reply);
 362         if (err)
 363                 rc = err;
 364
 365  out:
 366         u->len = 0;
 367         return rc;
 368 }
 369
 370 static int xenbus_dev_open(struct inode *inode, struct file *filp)
 371 {
 372         struct xenbus_dev_data *u;
 373
 374         if (xen_store_evtchn == 0)
 375                 return -ENOENT;
 376
 377         nonseekable_open(inode, filp);
 378
 379         u = kzalloc(sizeof(*u), GFP_KERNEL);
 380         if (u == NULL)
 381                 return -ENOMEM;
 382
 383         INIT_LIST_HEAD(&u->transactions);
 384         INIT_LIST_HEAD(&u->watches);
 385         INIT_LIST_HEAD(&u->read_buffers);
 386         init_waitqueue_head(&u->read_waitq);
 387
 388         mutex_init(&u->reply_mutex);
 389
 390         filp->private_data = u;
 391
 392         return 0;
 393 }
 394
 395 static int xenbus_dev_release(struct inode *inode, struct file *filp)
 396 {
 397         struct xenbus_dev_data *u = filp->private_data;
 398         struct xenbus_dev_transaction *trans, *tmp;
 399         struct watch_adapter *watch, *tmp_watch;
 400         struct read_buffer *rb, *tmp_rb;
 401
 402         list_for_each_entry_safe(trans, tmp, &u->transactions, list) {
 403                 xenbus_transaction_end(trans->handle, 1);
 404                 list_del(&trans->list);
 405                 kfree(trans);
 406         }
 407
 408         list_for_each_entry_safe(watch, tmp_watch, &u->watches, list) {
 409                 unregister_xenbus_watch(&watch->watch);
 410                 list_del(&watch->list);
 411                 free_watch_adapter(watch);
 412         }
 413
 414         list_for_each_entry_safe(rb, tmp_rb, &u->read_buffers, list) {
 415                 list_del(&rb->list);
 416                 kfree(rb);
 417         }
 418         kfree(u);
 419
 420         return 0;
 421 }
 422
 423 static unsigned int xenbus_dev_poll(struct file *file, poll_table *wait)
 424 {
 425         struct xenbus_dev_data *u = file->private_data;
 426
 427         if (!is_xenstored_ready())
 428                 return -ENODEV;
 429
 430         poll_wait(file, &u->read_waitq, wait);
 431         if (!list_empty(&u->read_buffers))
 432                 return POLLIN | POLLRDNORM;
 433         return 0;
 434 }
 435
 436 #ifdef CONFIG_XEN_PRIVILEGED_GUEST
 437 static long xenbus_dev_ioctl(struct file *file,
 438                              unsigned int cmd, unsigned long data)
 439 {
 440         void __user *udata = (void __user *) data;
 441         int ret = -ENOTTY;
 442
 443         if (!is_initial_xendomain())
 444                 return -ENODEV;
 445
 446
 447         switch (cmd) {
 448         case IOCTL_XENBUS_ALLOC: {
 449                 xenbus_alloc_t xa;
 450                 int old;
 451
 452                 old = atomic_cmpxchg(&xenbus_xsd_state,
 453                                      XENBUS_XSD_UNCOMMITTED,
 454                                      XENBUS_XSD_FOREIGN_INIT);
 455                 if (old != XENBUS_XSD_UNCOMMITTED)
 456                         return -EBUSY;
 457
 458                 if (copy_from_user(&xa, udata, sizeof(xa))) {
 459                         ret = -EFAULT;
 460                         atomic_set(&xenbus_xsd_state, XENBUS_XSD_UNCOMMITTED);
 461                         break;
 462                 }
 463
 464                 ret = xenbus_conn(xa.dom, &xa.grant_ref, &xa.port);
 465                 if (ret != 0) {
 466                         atomic_set(&xenbus_xsd_state, XENBUS_XSD_UNCOMMITTED);
 467                         break;
 468                 }
 469
 470                 if (copy_to_user(udata, &xa, sizeof(xa))) {
 471                         ret = -EFAULT;
 472                         atomic_set(&xenbus_xsd_state, XENBUS_XSD_UNCOMMITTED);
 473                         break;
 474                 }
 475         }
 476         break;
 477
 478         default:
 479                 break;
 480         }
 481
 482         return ret;
 483 }
 484 #endif
 485
 486 static const struct file_operations xenbus_dev_file_ops = {
 487         .read = xenbus_dev_read,
 488         .write = xenbus_dev_write,
 489         .open = xenbus_dev_open,
 490         .release = xenbus_dev_release,
 491         .llseek = no_llseek,
 492         .poll = xenbus_dev_poll,
 493 #ifdef CONFIG_XEN_PRIVILEGED_GUEST
 494         .unlocked_ioctl = xenbus_dev_ioctl
 495 #endif
 496 };
 497
 498 int
 499 #ifndef MODULE
 500 __init
 501 #else
 502 __devinit
 503 #endif
 504 xenbus_dev_init(void)
 505 {
 506         xenbus_dev_intf = create_xen_proc_entry("xenbus", 0400);
 507         if (xenbus_dev_intf)
 508                 xenbus_dev_intf->proc_fops = &xenbus_dev_file_ops;
 509
 510         return 0;
 511 }