drivers/hv/hv_kvp.c

   1 /*
   2  * An implementation of key value pair (KVP) functionality for Linux.
   3  *
   4  *
   5  * Copyright (C) 2010, Novell, Inc.
   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  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  21  *
  22  */
  23 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  24
  25 #include <linux/net.h>
  26 #include <linux/nls.h>
  27 #include <linux/connector.h>
  28 #include <linux/workqueue.h>
  29 #include <linux/hyperv.h>
  30
  31
  32
  33 /*
  34  * Global state maintained for transaction that is being processed.
  35  * Note that only one transaction can be active at any point in time.
  36  *
  37  * This state is set when we receive a request from the host; we
  38  * cleanup this state when the transaction is completed - when we respond
  39  * to the host with the key value.
  40  */
  41
  42 static struct {
  43         bool active; /* transaction status - active or not */
  44         int recv_len; /* number of bytes received. */
  45         struct hv_kvp_msg  *kvp_msg; /* current message */
  46         struct vmbus_channel *recv_channel; /* chn we got the request */
  47         u64 recv_req_id; /* request ID. */
  48         void *kvp_context; /* for the channel callback */
  49 } kvp_transaction;
  50
  51 static void kvp_send_key(struct work_struct *dummy);
  52
  53 #define TIMEOUT_FIRED 1
  54
  55 static void kvp_respond_to_host(char *key, char *value, int error);
  56 static void kvp_work_func(struct work_struct *dummy);
  57 static void kvp_register(void);
  58
  59 static DECLARE_DELAYED_WORK(kvp_work, kvp_work_func);
  60 static DECLARE_WORK(kvp_sendkey_work, kvp_send_key);
  61
  62 static struct cb_id kvp_id = { CN_KVP_IDX, CN_KVP_VAL };
  63 static const char kvp_name[] = "kvp_kernel_module";
  64 static u8 *recv_buffer;
  65 /*
  66  * Register the kernel component with the user-level daemon.
  67  * As part of this registration, pass the LIC version number.
  68  */
  69
  70 static void
  71 kvp_register(void)
  72 {
  73
  74         struct cn_msg *msg;
  75         struct hv_kvp_msg *kvp_msg;
  76         char *version;
  77
  78         msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg), GFP_ATOMIC);
  79
  80         if (msg) {
  81                 kvp_msg = (struct hv_kvp_msg *)msg->data;
  82                 version = kvp_msg->body.kvp_register.version;
  83                 msg->id.idx =  CN_KVP_IDX;
  84                 msg->id.val = CN_KVP_VAL;
  85
  86                 kvp_msg->kvp_hdr.operation = KVP_OP_REGISTER;
  87                 strcpy(version, HV_DRV_VERSION);
  88                 msg->len = sizeof(struct hv_kvp_msg);
  89                 cn_netlink_send(msg, 0, GFP_ATOMIC);
  90                 kfree(msg);
  91         }
  92 }
  93 static void
  94 kvp_work_func(struct work_struct *dummy)
  95 {
  96         /*
  97          * If the timer fires, the user-mode component has not responded;
  98          * process the pending transaction.
  99          */
 100         kvp_respond_to_host("Unknown key", "Guest timed out", TIMEOUT_FIRED);
 101 }
 102
 103 /*
 104  * Callback when data is received from user mode.
 105  */
 106
 107 static void
 108 kvp_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
 109 {
 110         struct hv_kvp_msg *message;
 111         struct hv_kvp_msg_enumerate *data;
 112
 113         message = (struct hv_kvp_msg *)msg->data;
 114         switch (message->kvp_hdr.operation) {
 115         case KVP_OP_REGISTER:
 116                 pr_info("KVP: user-mode registering done.\n");
 117                 kvp_register();
 118                 kvp_transaction.active = false;
 119                 hv_kvp_onchannelcallback(kvp_transaction.kvp_context);
 120                 break;
 121
 122         default:
 123                 data = &message->body.kvp_enum_data;
 124                 /*
 125                  * Complete the transaction by forwarding the key value
 126                  * to the host. But first, cancel the timeout.
 127                  */
 128                 if (cancel_delayed_work_sync(&kvp_work))
 129                         kvp_respond_to_host(data->data.key,
 130                                          data->data.value,
 131                                         !strlen(data->data.key));
 132         }
 133 }
 134
 135 static void
 136 kvp_send_key(struct work_struct *dummy)
 137 {
 138         struct cn_msg *msg;
 139         struct hv_kvp_msg *message;
 140         struct hv_kvp_msg *in_msg;
 141         __u8 operation = kvp_transaction.kvp_msg->kvp_hdr.operation;
 142         __u8 pool = kvp_transaction.kvp_msg->kvp_hdr.pool;
 143         __u32 val32;
 144         __u64 val64;
 145
 146         msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg) , GFP_ATOMIC);
 147         if (!msg)
 148                 return;
 149
 150         msg->id.idx =  CN_KVP_IDX;
 151         msg->id.val = CN_KVP_VAL;
 152
 153         message = (struct hv_kvp_msg *)msg->data;
 154         message->kvp_hdr.operation = operation;
 155         message->kvp_hdr.pool = pool;
 156         in_msg = kvp_transaction.kvp_msg;
 157
 158         /*
 159          * The key/value strings sent from the host are encoded in
 160          * in utf16; convert it to utf8 strings.
 161          * The host assures us that the utf16 strings will not exceed
 162          * the max lengths specified. We will however, reserve room
 163          * for the string terminating character - in the utf16s_utf8s()
 164          * function we limit the size of the buffer where the converted
 165          * string is placed to HV_KVP_EXCHANGE_MAX_*_SIZE -1 to gaurantee
 166          * that the strings can be properly terminated!
 167          */
 168
 169         switch (message->kvp_hdr.operation) {
 170         case KVP_OP_SET:
 171                 switch (in_msg->body.kvp_set.data.value_type) {
 172                 case REG_SZ:
 173                         /*
 174                          * The value is a string - utf16 encoding.
 175                          */
 176                         message->body.kvp_set.data.value_size =
 177                                 utf16s_to_utf8s(
 178                                 (wchar_t *)in_msg->body.kvp_set.data.value,
 179                                 in_msg->body.kvp_set.data.value_size,
 180                                 UTF16_LITTLE_ENDIAN,
 181                                 message->body.kvp_set.data.value,
 182                                 HV_KVP_EXCHANGE_MAX_VALUE_SIZE - 1) + 1;
 183                                 break;
 184
 185                 case REG_U32:
 186                         /*
 187                          * The value is a 32 bit scalar.
 188                          * We save this as a utf8 string.
 189                          */
 190                         val32 = in_msg->body.kvp_set.data.value_u32;
 191                         message->body.kvp_set.data.value_size =
 192                                 sprintf(message->body.kvp_set.data.value,
 193                                         "%d", val32) + 1;
 194                         break;
 195
 196                 case REG_U64:
 197                         /*
 198                          * The value is a 64 bit scalar.
 199                          * We save this as a utf8 string.
 200                          */
 201                         val64 = in_msg->body.kvp_set.data.value_u64;
 202                         message->body.kvp_set.data.value_size =
 203                                 sprintf(message->body.kvp_set.data.value,
 204                                         "%llu", val64) + 1;
 205                         break;
 206
 207                 }
 208         case KVP_OP_GET:
 209                 message->body.kvp_set.data.key_size =
 210                         utf16s_to_utf8s(
 211                         (wchar_t *)in_msg->body.kvp_set.data.key,
 212                         in_msg->body.kvp_set.data.key_size,
 213                         UTF16_LITTLE_ENDIAN,
 214                         message->body.kvp_set.data.key,
 215                         HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
 216                         break;
 217
 218         case KVP_OP_DELETE:
 219                 message->body.kvp_delete.key_size =
 220                         utf16s_to_utf8s(
 221                         (wchar_t *)in_msg->body.kvp_delete.key,
 222                         in_msg->body.kvp_delete.key_size,
 223                         UTF16_LITTLE_ENDIAN,
 224                         message->body.kvp_delete.key,
 225                         HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
 226                         break;
 227
 228         case KVP_OP_ENUMERATE:
 229                 message->body.kvp_enum_data.index =
 230                         in_msg->body.kvp_enum_data.index;
 231                         break;
 232         }
 233
 234         msg->len = sizeof(struct hv_kvp_msg);
 235         cn_netlink_send(msg, 0, GFP_ATOMIC);
 236         kfree(msg);
 237
 238         return;
 239 }
 240
 241 /*
 242  * Send a response back to the host.
 243  */
 244
 245 static void
 246 kvp_respond_to_host(char *key, char *value, int error)
 247 {
 248         struct hv_kvp_msg  *kvp_msg;
 249         struct hv_kvp_exchg_msg_value  *kvp_data;
 250         char    *key_name;
 251         struct icmsg_hdr *icmsghdrp;
 252         int     keylen = 0;
 253         int     valuelen = 0;
 254         u32     buf_len;
 255         struct vmbus_channel *channel;
 256         u64     req_id;
 257
 258         /*
 259          * If a transaction is not active; log and return.
 260          */
 261
 262         if (!kvp_transaction.active) {
 263                 /*
 264                  * This is a spurious call!
 265                  */
 266                 pr_warn("KVP: Transaction not active\n");
 267                 return;
 268         }
 269         /*
 270          * Copy the global state for completing the transaction. Note that
 271          * only one transaction can be active at a time.
 272          */
 273
 274         buf_len = kvp_transaction.recv_len;
 275         channel = kvp_transaction.recv_channel;
 276         req_id = kvp_transaction.recv_req_id;
 277
 278         kvp_transaction.active = false;
 279
 280         icmsghdrp = (struct icmsg_hdr *)
 281                         &recv_buffer[sizeof(struct vmbuspipe_hdr)];
 282
 283         if (channel->onchannel_callback == NULL)
 284                 /*
 285                  * We have raced with util driver being unloaded;
 286                  * silently return.
 287                  */
 288                 return;
 289
 290
 291         /*
 292          * If the error parameter is set, terminate the host's enumeration
 293          * on this pool.
 294          */
 295         if (error) {
 296                 /*
 297                  * Something failed or the we have timedout;
 298                  * terminate the current  host-side iteration.
 299                  */
 300                 icmsghdrp->status = HV_S_CONT;
 301                 goto response_done;
 302         }
 303
 304         icmsghdrp->status = HV_S_OK;
 305
 306         kvp_msg = (struct hv_kvp_msg *)
 307                         &recv_buffer[sizeof(struct vmbuspipe_hdr) +
 308                         sizeof(struct icmsg_hdr)];
 309
 310         switch (kvp_transaction.kvp_msg->kvp_hdr.operation) {
 311         case KVP_OP_GET:
 312                 kvp_data = &kvp_msg->body.kvp_get.data;
 313                 goto copy_value;
 314
 315         case KVP_OP_SET:
 316         case KVP_OP_DELETE:
 317                 goto response_done;
 318
 319         default:
 320                 break;
 321         }
 322
 323         kvp_data = &kvp_msg->body.kvp_enum_data.data;
 324         key_name = key;
 325
 326         /*
 327          * The windows host expects the key/value pair to be encoded
 328          * in utf16. Ensure that the key/value size reported to the host
 329          * will be less than or equal to the MAX size (including the
 330          * terminating character).
 331          */
 332         keylen = utf8s_to_utf16s(key_name, strlen(key_name), UTF16_HOST_ENDIAN,
 333                                 (wchar_t *) kvp_data->key,
 334                                 (HV_KVP_EXCHANGE_MAX_KEY_SIZE / 2) - 2);
 335         kvp_data->key_size = 2*(keylen + 1); /* utf16 encoding */
 336
 337 copy_value:
 338         valuelen = utf8s_to_utf16s(value, strlen(value), UTF16_HOST_ENDIAN,
 339                                 (wchar_t *) kvp_data->value,
 340                                 (HV_KVP_EXCHANGE_MAX_VALUE_SIZE / 2) - 2);
 341         kvp_data->value_size = 2*(valuelen + 1); /* utf16 encoding */
 342
 343         /*
 344          * If the utf8s to utf16s conversion failed; notify host
 345          * of the error.
 346          */
 347         if ((keylen < 0) || (valuelen < 0))
 348                 icmsghdrp->status = HV_E_FAIL;
 349
 350         kvp_data->value_type = REG_SZ; /* all our values are strings */
 351
 352 response_done:
 353         icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;
 354
 355         vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
 356                                 VM_PKT_DATA_INBAND, 0);
 357
 358 }
 359
 360 /*
 361  * This callback is invoked when we get a KVP message from the host.
 362  * The host ensures that only one KVP transaction can be active at a time.
 363  * KVP implementation in Linux needs to forward the key to a user-mde
 364  * component to retrive the corresponding value. Consequently, we cannot
 365  * respond to the host in the conext of this callback. Since the host
 366  * guarantees that at most only one transaction can be active at a time,
 367  * we stash away the transaction state in a set of global variables.
 368  */
 369
 370 void hv_kvp_onchannelcallback(void *context)
 371 {
 372         struct vmbus_channel *channel = context;
 373         u32 recvlen;
 374         u64 requestid;
 375
 376         struct hv_kvp_msg *kvp_msg;
 377
 378         struct icmsg_hdr *icmsghdrp;
 379         struct icmsg_negotiate *negop = NULL;
 380
 381         if (kvp_transaction.active) {
 382                 /*
 383                  * We will defer processing this callback once
 384                  * the current transaction is complete.
 385                  */
 386                 kvp_transaction.kvp_context = context;
 387                 return;
 388         }
 389
 390         vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE, &recvlen, &requestid);
 391
 392         if (recvlen > 0) {
 393                 icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
 394                         sizeof(struct vmbuspipe_hdr)];
 395
 396                 if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
 397                         vmbus_prep_negotiate_resp(icmsghdrp, negop,
 398                                  recv_buffer, MAX_SRV_VER, MAX_SRV_VER);
 399                 } else {
 400                         kvp_msg = (struct hv_kvp_msg *)&recv_buffer[
 401                                 sizeof(struct vmbuspipe_hdr) +
 402                                 sizeof(struct icmsg_hdr)];
 403
 404                         /*
 405                          * Stash away this global state for completing the
 406                          * transaction; note transactions are serialized.
 407                          */
 408
 409                         kvp_transaction.recv_len = recvlen;
 410                         kvp_transaction.recv_channel = channel;
 411                         kvp_transaction.recv_req_id = requestid;
 412                         kvp_transaction.active = true;
 413                         kvp_transaction.kvp_msg = kvp_msg;
 414
 415                         /*
 416                          * Get the information from the
 417                          * user-mode component.
 418                          * component. This transaction will be
 419                          * completed when we get the value from
 420                          * the user-mode component.
 421                          * Set a timeout to deal with
 422                          * user-mode not responding.
 423                          */
 424                         schedule_work(&kvp_sendkey_work);
 425                         schedule_delayed_work(&kvp_work, 5*HZ);
 426
 427                         return;
 428
 429                 }
 430
 431                 icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
 432                         | ICMSGHDRFLAG_RESPONSE;
 433
 434                 vmbus_sendpacket(channel, recv_buffer,
 435                                        recvlen, requestid,
 436                                        VM_PKT_DATA_INBAND, 0);
 437         }
 438
 439 }
 440
 441 int
 442 hv_kvp_init(struct hv_util_service *srv)
 443 {
 444         int err;
 445
 446         err = cn_add_callback(&kvp_id, kvp_name, kvp_cn_callback);
 447         if (err)
 448                 return err;
 449         recv_buffer = srv->recv_buffer;
 450
 451         /*
 452          * When this driver loads, the user level daemon that
 453          * processes the host requests may not yet be running.
 454          * Defer processing channel callbacks until the daemon
 455          * has registered.
 456          */
 457         kvp_transaction.active = true;
 458
 459         return 0;
 460 }
 461
 462 void hv_kvp_deinit(void)
 463 {
 464         cn_del_callback(&kvp_id);
 465         cancel_delayed_work_sync(&kvp_work);
 466         cancel_work_sync(&kvp_sendkey_work);
 467 }