drivers/hv/hv_fcopy.c

   1 /*
   2  * An implementation of file copy service.
   3  *
   4  * Copyright (C) 2014, Microsoft, Inc.
   5  *
   6  * Author : K. Y. Srinivasan <ksrinivasan@novell.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License version 2 as published
  10  * by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  15  * NON INFRINGEMENT.  See the GNU General Public License for more
  16  * details.
  17  *
  18  */
  19
  20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  21
  22 #include <linux/semaphore.h>
  23 #include <linux/fs.h>
  24 #include <linux/nls.h>
  25 #include <linux/workqueue.h>
  26 #include <linux/cdev.h>
  27 #include <linux/hyperv.h>
  28 #include <linux/sched.h>
  29 #include <linux/uaccess.h>
  30 #include <linux/miscdevice.h>
  31
  32 #include "hyperv_vmbus.h"
  33
  34 #define WIN8_SRV_MAJOR          1
  35 #define WIN8_SRV_MINOR          1
  36 #define WIN8_SRV_VERSION        (WIN8_SRV_MAJOR << 16 | WIN8_SRV_MINOR)
  37
  38 /*
  39  * Global state maintained for transaction that is being processed.
  40  * For a class of integration services, including the "file copy service",
  41  * the specified protocol is a "request/response" protocol which means that
  42  * there can only be single outstanding transaction from the host at any
  43  * given point in time. We use this to simplify memory management in this
  44  * driver - we cache and process only one message at a time.
  45  *
  46  * While the request/response protocol is guaranteed by the host, we further
  47  * ensure this by serializing packet processing in this driver - we do not
  48  * read additional packets from the VMBUs until the current packet is fully
  49  * handled.
  50  *
  51  * The transaction "active" state is set when we receive a request from the
  52  * host and we cleanup this state when the transaction is completed - when we
  53  * respond to the host with our response. When the transaction active state is
  54  * set, we defer handling incoming packets.
  55  */
  56
  57 static struct {
  58         bool active; /* transaction status - active or not */
  59         int recv_len; /* number of bytes received. */
  60         struct hv_fcopy_hdr  *fcopy_msg; /* current message */
  61         struct hv_start_fcopy  message; /*  sent to daemon */
  62         struct vmbus_channel *recv_channel; /* chn we got the request */
  63         u64 recv_req_id; /* request ID. */
  64         void *fcopy_context; /* for the channel callback */
  65         struct semaphore read_sema;
  66 } fcopy_transaction;
  67
  68 static bool opened; /* currently device opened */
  69
  70 /*
  71  * Before we can accept copy messages from the host, we need
  72  * to handshake with the user level daemon. This state tracks
  73  * if we are in the handshake phase.
  74  */
  75 static bool in_hand_shake = true;
  76 static void fcopy_send_data(void);
  77 static void fcopy_respond_to_host(int error);
  78 static void fcopy_work_func(struct work_struct *dummy);
  79 static DECLARE_DELAYED_WORK(fcopy_work, fcopy_work_func);
  80 static u8 *recv_buffer;
  81
  82 static void fcopy_work_func(struct work_struct *dummy)
  83 {
  84         /*
  85          * If the timer fires, the user-mode component has not responded;
  86          * process the pending transaction.
  87          */
  88         fcopy_respond_to_host(HV_E_FAIL);
  89 }
  90
  91 static int fcopy_handle_handshake(u32 version)
  92 {
  93         switch (version) {
  94         case FCOPY_CURRENT_VERSION:
  95                 break;
  96         default:
  97                 /*
  98                  * For now we will fail the registration.
  99                  * If and when we have multiple versions to
 100                  * deal with, we will be backward compatible.
 101                  * We will add this code when needed.
 102                  */
 103                 return -EINVAL;
 104         }
 105         pr_info("FCP: user-mode registering done. Daemon version: %d\n",
 106                 version);
 107         fcopy_transaction.active = false;
 108         if (fcopy_transaction.fcopy_context)
 109                 hv_fcopy_onchannelcallback(fcopy_transaction.fcopy_context);
 110         in_hand_shake = false;
 111         return 0;
 112 }
 113
 114 static void fcopy_send_data(void)
 115 {
 116         struct hv_start_fcopy *smsg_out = &fcopy_transaction.message;
 117         int operation = fcopy_transaction.fcopy_msg->operation;
 118         struct hv_start_fcopy *smsg_in;
 119
 120         /*
 121          * The  strings sent from the host are encoded in
 122          * in utf16; convert it to utf8 strings.
 123          * The host assures us that the utf16 strings will not exceed
 124          * the max lengths specified. We will however, reserve room
 125          * for the string terminating character - in the utf16s_utf8s()
 126          * function we limit the size of the buffer where the converted
 127          * string is placed to W_MAX_PATH -1 to guarantee
 128          * that the strings can be properly terminated!
 129          */
 130
 131         switch (operation) {
 132         case START_FILE_COPY:
 133                 memset(smsg_out, 0, sizeof(struct hv_start_fcopy));
 134                 smsg_out->hdr.operation = operation;
 135                 smsg_in = (struct hv_start_fcopy *)fcopy_transaction.fcopy_msg;
 136
 137                 utf16s_to_utf8s((wchar_t *)smsg_in->file_name, W_MAX_PATH,
 138                                 UTF16_LITTLE_ENDIAN,
 139                                 (__u8 *)smsg_out->file_name, W_MAX_PATH - 1);
 140
 141                 utf16s_to_utf8s((wchar_t *)smsg_in->path_name, W_MAX_PATH,
 142                                 UTF16_LITTLE_ENDIAN,
 143                                 (__u8 *)smsg_out->path_name, W_MAX_PATH - 1);
 144
 145                 smsg_out->copy_flags = smsg_in->copy_flags;
 146                 smsg_out->file_size = smsg_in->file_size;
 147                 break;
 148
 149         default:
 150                 break;
 151         }
 152         up(&fcopy_transaction.read_sema);
 153         return;
 154 }
 155
 156 /*
 157  * Send a response back to the host.
 158  */
 159
 160 static void
 161 fcopy_respond_to_host(int error)
 162 {
 163         struct icmsg_hdr *icmsghdr;
 164         u32 buf_len;
 165         struct vmbus_channel *channel;
 166         u64 req_id;
 167
 168         /*
 169          * Copy the global state for completing the transaction. Note that
 170          * only one transaction can be active at a time. This is guaranteed
 171          * by the file copy protocol implemented by the host. Furthermore,
 172          * the "transaction active" state we maintain ensures that there can
 173          * only be one active transaction at a time.
 174          */
 175
 176         buf_len = fcopy_transaction.recv_len;
 177         channel = fcopy_transaction.recv_channel;
 178         req_id = fcopy_transaction.recv_req_id;
 179
 180         fcopy_transaction.active = false;
 181
 182         icmsghdr = (struct icmsg_hdr *)
 183                         &recv_buffer[sizeof(struct vmbuspipe_hdr)];
 184
 185         if (channel->onchannel_callback == NULL)
 186                 /*
 187                  * We have raced with util driver being unloaded;
 188                  * silently return.
 189                  */
 190                 return;
 191
 192         icmsghdr->status = error;
 193         icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 194         vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
 195                                 VM_PKT_DATA_INBAND, 0);
 196 }
 197
 198 void hv_fcopy_onchannelcallback(void *context)
 199 {
 200         struct vmbus_channel *channel = context;
 201         u32 recvlen;
 202         u64 requestid;
 203         struct hv_fcopy_hdr *fcopy_msg;
 204         struct icmsg_hdr *icmsghdr;
 205         struct icmsg_negotiate *negop = NULL;
 206         int util_fw_version;
 207         int fcopy_srv_version;
 208
 209         if (fcopy_transaction.active) {
 210                 /*
 211                  * We will defer processing this callback once
 212                  * the current transaction is complete.
 213                  */
 214                 fcopy_transaction.fcopy_context = context;
 215                 return;
 216         }
 217
 218         vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
 219                          &requestid);
 220         if (recvlen <= 0)
 221                 return;
 222
 223         icmsghdr = (struct icmsg_hdr *)&recv_buffer[
 224                         sizeof(struct vmbuspipe_hdr)];
 225         if (icmsghdr->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 226                 util_fw_version = UTIL_FW_VERSION;
 227                 fcopy_srv_version = WIN8_SRV_VERSION;
 228                 vmbus_prep_negotiate_resp(icmsghdr, negop, recv_buffer,
 229                                 util_fw_version, fcopy_srv_version);
 230         } else {
 231                 fcopy_msg = (struct hv_fcopy_hdr *)&recv_buffer[
 232                                 sizeof(struct vmbuspipe_hdr) +
 233                                 sizeof(struct icmsg_hdr)];
 234
 235                 /*
 236                  * Stash away this global state for completing the
 237                  * transaction; note transactions are serialized.
 238                  */
 239
 240                 fcopy_transaction.active = true;
 241                 fcopy_transaction.recv_len = recvlen;
 242                 fcopy_transaction.recv_channel = channel;
 243                 fcopy_transaction.recv_req_id = requestid;
 244                 fcopy_transaction.fcopy_msg = fcopy_msg;
 245
 246                 /*
 247                  * Send the information to the user-level daemon.
 248                  */
 249                 schedule_delayed_work(&fcopy_work, 5*HZ);
 250                 fcopy_send_data();
 251                 return;
 252         }
 253         icmsghdr->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 254         vmbus_sendpacket(channel, recv_buffer, recvlen, requestid,
 255                         VM_PKT_DATA_INBAND, 0);
 256 }
 257
 258 /*
 259  * Create a char device that can support read/write for passing
 260  * the payload.
 261  */
 262
 263 static ssize_t fcopy_read(struct file *file, char __user *buf,
 264                 size_t count, loff_t *ppos)
 265 {
 266         void *src;
 267         size_t copy_size;
 268         int operation;
 269
 270         /*
 271          * Wait until there is something to be read.
 272          */
 273         if (down_interruptible(&fcopy_transaction.read_sema))
 274                 return -EINTR;
 275
 276         /*
 277          * The channel may be rescinded and in this case, we will wakeup the
 278          * the thread blocked on the semaphore and we will use the opened
 279          * state to correctly handle this case.
 280          */
 281         if (!opened)
 282                 return -ENODEV;
 283
 284         operation = fcopy_transaction.fcopy_msg->operation;
 285
 286         if (operation == START_FILE_COPY) {
 287                 src = &fcopy_transaction.message;
 288                 copy_size = sizeof(struct hv_start_fcopy);
 289                 if (count < copy_size)
 290                         return 0;
 291         } else {
 292                 src = fcopy_transaction.fcopy_msg;
 293                 copy_size = sizeof(struct hv_do_fcopy);
 294                 if (count < copy_size)
 295                         return 0;
 296         }
 297         if (copy_to_user(buf, src, copy_size))
 298                 return -EFAULT;
 299
 300         return copy_size;
 301 }
 302
 303 static ssize_t fcopy_write(struct file *file, const char __user *buf,
 304                         size_t count, loff_t *ppos)
 305 {
 306         int response = 0;
 307
 308         if (count != sizeof(int))
 309                 return -EINVAL;
 310
 311         if (copy_from_user(&response, buf, sizeof(int)))
 312                 return -EFAULT;
 313
 314         if (in_hand_shake) {
 315                 if (fcopy_handle_handshake(response))
 316                         return -EINVAL;
 317                 return sizeof(int);
 318         }
 319
 320         /*
 321          * Complete the transaction by forwarding the result
 322          * to the host. But first, cancel the timeout.
 323          */
 324         if (cancel_delayed_work_sync(&fcopy_work))
 325                 fcopy_respond_to_host(response);
 326
 327         return sizeof(int);
 328 }
 329
 330 static int fcopy_open(struct inode *inode, struct file *f)
 331 {
 332         /*
 333          * The user level daemon that will open this device is
 334          * really an extension of this driver. We can have only
 335          * active open at a time.
 336          */
 337         if (opened)
 338                 return -EBUSY;
 339
 340         /*
 341          * The daemon is alive; setup the state.
 342          */
 343         opened = true;
 344         return 0;
 345 }
 346
 347 static int fcopy_release(struct inode *inode, struct file *f)
 348 {
 349         /*
 350          * The daemon has exited; reset the state.
 351          */
 352         in_hand_shake = true;
 353         opened = false;
 354         return 0;
 355 }
 356
 357
 358 static const struct file_operations fcopy_fops = {
 359         .read           = fcopy_read,
 360         .write          = fcopy_write,
 361         .release        = fcopy_release,
 362         .open           = fcopy_open,
 363 };
 364
 365 static struct miscdevice fcopy_misc = {
 366         .minor          = MISC_DYNAMIC_MINOR,
 367         .name           = "vmbus/hv_fcopy",
 368         .fops           = &fcopy_fops,
 369 };
 370
 371 static int fcopy_dev_init(void)
 372 {
 373         return misc_register(&fcopy_misc);
 374 }
 375
 376 static void fcopy_dev_deinit(void)
 377 {
 378
 379         /*
 380          * The device is going away - perhaps because the
 381          * host has rescinded the channel. Setup state so that
 382          * user level daemon can gracefully exit if it is blocked
 383          * on the read semaphore.
 384          */
 385         opened = false;
 386         /*
 387          * Signal the semaphore as the device is
 388          * going away.
 389          */
 390         up(&fcopy_transaction.read_sema);
 391         misc_deregister(&fcopy_misc);
 392 }
 393
 394 int hv_fcopy_init(struct hv_util_service *srv)
 395 {
 396         recv_buffer = srv->recv_buffer;
 397
 398         /*
 399          * When this driver loads, the user level daemon that
 400          * processes the host requests may not yet be running.
 401          * Defer processing channel callbacks until the daemon
 402          * has registered.
 403          */
 404         fcopy_transaction.active = true;
 405         sema_init(&fcopy_transaction.read_sema, 0);
 406
 407         return fcopy_dev_init();
 408 }
 409
 410 void hv_fcopy_deinit(void)
 411 {
 412         cancel_delayed_work_sync(&fcopy_work);
 413         fcopy_dev_deinit();
 414 }