fs/lockd/mon.c

   1 /*
   2  * linux/fs/lockd/mon.c
   3  *
   4  * The kernel statd client.
   5  *
   6  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/utsname.h>
  11 #include <linux/kernel.h>
  12 #include <linux/ktime.h>
  13 #include <linux/slab.h>
  14
  15 #include <linux/sunrpc/clnt.h>
  16 #include <linux/sunrpc/xprtsock.h>
  17 #include <linux/sunrpc/svc.h>
  18 #include <linux/lockd/lockd.h>
  19
  20 #include <asm/unaligned.h>
  21
  22 #define NLMDBG_FACILITY         NLMDBG_MONITOR
  23 #define NSM_PROGRAM             100024
  24 #define NSM_VERSION             1
  25
  26 enum {
  27         NSMPROC_NULL,
  28         NSMPROC_STAT,
  29         NSMPROC_MON,
  30         NSMPROC_UNMON,
  31         NSMPROC_UNMON_ALL,
  32         NSMPROC_SIMU_CRASH,
  33         NSMPROC_NOTIFY,
  34 };
  35
  36 struct nsm_args {
  37         struct nsm_private      *priv;
  38         u32                     prog;           /* RPC callback info */
  39         u32                     vers;
  40         u32                     proc;
  41
  42         char                    *mon_name;
  43 };
  44
  45 struct nsm_res {
  46         u32                     status;
  47         u32                     state;
  48 };
  49
  50 static struct rpc_program       nsm_program;
  51 static                          LIST_HEAD(nsm_handles);
  52 static                          DEFINE_SPINLOCK(nsm_lock);
  53
  54 /*
  55  * Local NSM state
  56  */
  57 u32     __read_mostly           nsm_local_state;
  58 int     __read_mostly           nsm_use_hostnames;
  59
  60 static inline struct sockaddr *nsm_addr(const struct nsm_handle *nsm)
  61 {
  62         return (struct sockaddr *)&nsm->sm_addr;
  63 }
  64
  65 static struct rpc_clnt *nsm_create(void)
  66 {
  67         struct sockaddr_in sin = {
  68                 .sin_family             = AF_INET,
  69                 .sin_addr.s_addr        = htonl(INADDR_LOOPBACK),
  70         };
  71         struct rpc_create_args args = {
  72                 .net                    = &init_net,
  73                 .protocol               = XPRT_TRANSPORT_UDP,
  74                 .address                = (struct sockaddr *)&sin,
  75                 .addrsize               = sizeof(sin),
  76                 .servername             = "rpc.statd",
  77                 .program                = &nsm_program,
  78                 .version                = NSM_VERSION,
  79                 .authflavor             = RPC_AUTH_NULL,
  80                 .flags                  = RPC_CLNT_CREATE_NOPING,
  81         };
  82
  83         return rpc_create(&args);
  84 }
  85
  86 static int nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res)
  87 {
  88         struct rpc_clnt *clnt;
  89         int             status;
  90         struct nsm_args args = {
  91                 .priv           = &nsm->sm_priv,
  92                 .prog           = NLM_PROGRAM,
  93                 .vers           = 3,
  94                 .proc           = NLMPROC_NSM_NOTIFY,
  95                 .mon_name       = nsm->sm_mon_name,
  96         };
  97         struct rpc_message msg = {
  98                 .rpc_argp       = &args,
  99                 .rpc_resp       = res,
 100         };
 101
 102         clnt = nsm_create();
 103         if (IS_ERR(clnt)) {
 104                 status = PTR_ERR(clnt);
 105                 dprintk("lockd: failed to create NSM upcall transport, "
 106                                 "status=%d\n", status);
 107                 goto out;
 108         }
 109
 110         memset(res, 0, sizeof(*res));
 111
 112         msg.rpc_proc = &clnt->cl_procinfo[proc];
 113         status = rpc_call_sync(clnt, &msg, 0);
 114         if (status < 0)
 115                 dprintk("lockd: NSM upcall RPC failed, status=%d\n",
 116                                 status);
 117         else
 118                 status = 0;
 119         rpc_shutdown_client(clnt);
 120  out:
 121         return status;
 122 }
 123
 124 /**
 125  * nsm_monitor - Notify a peer in case we reboot
 126  * @host: pointer to nlm_host of peer to notify
 127  *
 128  * If this peer is not already monitored, this function sends an
 129  * upcall to the local rpc.statd to record the name/address of
 130  * the peer to notify in case we reboot.
 131  *
 132  * Returns zero if the peer is monitored by the local rpc.statd;
 133  * otherwise a negative errno value is returned.
 134  */
 135 int nsm_monitor(const struct nlm_host *host)
 136 {
 137         struct nsm_handle *nsm = host->h_nsmhandle;
 138         struct nsm_res  res;
 139         int             status;
 140
 141         dprintk("lockd: nsm_monitor(%s)\n", nsm->sm_name);
 142
 143         if (nsm->sm_monitored)
 144                 return 0;
 145
 146         /*
 147          * Choose whether to record the caller_name or IP address of
 148          * this peer in the local rpc.statd's database.
 149          */
 150         nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf;
 151
 152         status = nsm_mon_unmon(nsm, NSMPROC_MON, &res);
 153         if (unlikely(res.status != 0))
 154                 status = -EIO;
 155         if (unlikely(status < 0)) {
 156                 printk(KERN_NOTICE "lockd: cannot monitor %s\n", nsm->sm_name);
 157                 return status;
 158         }
 159
 160         nsm->sm_monitored = 1;
 161         if (unlikely(nsm_local_state != res.state)) {
 162                 nsm_local_state = res.state;
 163                 dprintk("lockd: NSM state changed to %d\n", nsm_local_state);
 164         }
 165         return 0;
 166 }
 167
 168 /**
 169  * nsm_unmonitor - Unregister peer notification
 170  * @host: pointer to nlm_host of peer to stop monitoring
 171  *
 172  * If this peer is monitored, this function sends an upcall to
 173  * tell the local rpc.statd not to send this peer a notification
 174  * when we reboot.
 175  */
 176 void nsm_unmonitor(const struct nlm_host *host)
 177 {
 178         struct nsm_handle *nsm = host->h_nsmhandle;
 179         struct nsm_res  res;
 180         int status;
 181
 182         if (atomic_read(&nsm->sm_count) == 1
 183          && nsm->sm_monitored && !nsm->sm_sticky) {
 184                 dprintk("lockd: nsm_unmonitor(%s)\n", nsm->sm_name);
 185
 186                 status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res);
 187                 if (res.status != 0)
 188                         status = -EIO;
 189                 if (status < 0)
 190                         printk(KERN_NOTICE "lockd: cannot unmonitor %s\n",
 191                                         nsm->sm_name);
 192                 else
 193                         nsm->sm_monitored = 0;
 194         }
 195 }
 196
 197 static struct nsm_handle *nsm_lookup_hostname(const char *hostname,
 198                                               const size_t len)
 199 {
 200         struct nsm_handle *nsm;
 201
 202         list_for_each_entry(nsm, &nsm_handles, sm_link)
 203                 if (strlen(nsm->sm_name) == len &&
 204                     memcmp(nsm->sm_name, hostname, len) == 0)
 205                         return nsm;
 206         return NULL;
 207 }
 208
 209 static struct nsm_handle *nsm_lookup_addr(const struct sockaddr *sap)
 210 {
 211         struct nsm_handle *nsm;
 212
 213         list_for_each_entry(nsm, &nsm_handles, sm_link)
 214                 if (rpc_cmp_addr(nsm_addr(nsm), sap))
 215                         return nsm;
 216         return NULL;
 217 }
 218
 219 static struct nsm_handle *nsm_lookup_priv(const struct nsm_private *priv)
 220 {
 221         struct nsm_handle *nsm;
 222
 223         list_for_each_entry(nsm, &nsm_handles, sm_link)
 224                 if (memcmp(nsm->sm_priv.data, priv->data,
 225                                         sizeof(priv->data)) == 0)
 226                         return nsm;
 227         return NULL;
 228 }
 229
 230 /*
 231  * Construct a unique cookie to match this nsm_handle to this monitored
 232  * host.  It is passed to the local rpc.statd via NSMPROC_MON, and
 233  * returned via NLMPROC_SM_NOTIFY, in the "priv" field of these
 234  * requests.
 235  *
 236  * The NSM protocol requires that these cookies be unique while the
 237  * system is running.  We prefer a stronger requirement of making them
 238  * unique across reboots.  If user space bugs cause a stale cookie to
 239  * be sent to the kernel, it could cause the wrong host to lose its
 240  * lock state if cookies were not unique across reboots.
 241  *
 242  * The cookies are exposed only to local user space via loopback.  They
 243  * do not appear on the physical network.  If we want greater security
 244  * for some reason, nsm_init_private() could perform a one-way hash to
 245  * obscure the contents of the cookie.
 246  */
 247 static void nsm_init_private(struct nsm_handle *nsm)
 248 {
 249         u64 *p = (u64 *)&nsm->sm_priv.data;
 250         struct timespec ts;
 251         s64 ns;
 252
 253         ktime_get_ts(&ts);
 254         ns = timespec_to_ns(&ts);
 255         put_unaligned(ns, p);
 256         put_unaligned((unsigned long)nsm, p + 1);
 257 }
 258
 259 static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
 260                                             const size_t salen,
 261                                             const char *hostname,
 262                                             const size_t hostname_len)
 263 {
 264         struct nsm_handle *new;
 265
 266         new = kzalloc(sizeof(*new) + hostname_len + 1, GFP_KERNEL);
 267         if (unlikely(new == NULL))
 268                 return NULL;
 269
 270         atomic_set(&new->sm_count, 1);
 271         new->sm_name = (char *)(new + 1);
 272         memcpy(nsm_addr(new), sap, salen);
 273         new->sm_addrlen = salen;
 274         nsm_init_private(new);
 275
 276         if (rpc_ntop(nsm_addr(new), new->sm_addrbuf,
 277                                         sizeof(new->sm_addrbuf)) == 0)
 278                 (void)snprintf(new->sm_addrbuf, sizeof(new->sm_addrbuf),
 279                                 "unsupported address family");
 280         memcpy(new->sm_name, hostname, hostname_len);
 281         new->sm_name[hostname_len] = '\0';
 282
 283         return new;
 284 }
 285
 286 /**
 287  * nsm_get_handle - Find or create a cached nsm_handle
 288  * @sap: pointer to socket address of handle to find
 289  * @salen: length of socket address
 290  * @hostname: pointer to C string containing hostname to find
 291  * @hostname_len: length of C string
 292  *
 293  * Behavior is modulated by the global nsm_use_hostnames variable.
 294  *
 295  * Returns a cached nsm_handle after bumping its ref count, or
 296  * returns a fresh nsm_handle if a handle that matches @sap and/or
 297  * @hostname cannot be found in the handle cache.  Returns NULL if
 298  * an error occurs.
 299  */
 300 struct nsm_handle *nsm_get_handle(const struct sockaddr *sap,
 301                                   const size_t salen, const char *hostname,
 302                                   const size_t hostname_len)
 303 {
 304         struct nsm_handle *cached, *new = NULL;
 305
 306         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 307                 if (printk_ratelimit()) {
 308                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 309                                             "in NFS lock request\n",
 310                                 (int)hostname_len, hostname);
 311                 }
 312                 return NULL;
 313         }
 314
 315 retry:
 316         spin_lock(&nsm_lock);
 317
 318         if (nsm_use_hostnames && hostname != NULL)
 319                 cached = nsm_lookup_hostname(hostname, hostname_len);
 320         else
 321                 cached = nsm_lookup_addr(sap);
 322
 323         if (cached != NULL) {
 324                 atomic_inc(&cached->sm_count);
 325                 spin_unlock(&nsm_lock);
 326                 kfree(new);
 327                 dprintk("lockd: found nsm_handle for %s (%s), "
 328                                 "cnt %d\n", cached->sm_name,
 329                                 cached->sm_addrbuf,
 330                                 atomic_read(&cached->sm_count));
 331                 return cached;
 332         }
 333
 334         if (new != NULL) {
 335                 list_add(&new->sm_link, &nsm_handles);
 336                 spin_unlock(&nsm_lock);
 337                 dprintk("lockd: created nsm_handle for %s (%s)\n",
 338                                 new->sm_name, new->sm_addrbuf);
 339                 return new;
 340         }
 341
 342         spin_unlock(&nsm_lock);
 343
 344         new = nsm_create_handle(sap, salen, hostname, hostname_len);
 345         if (unlikely(new == NULL))
 346                 return NULL;
 347         goto retry;
 348 }
 349
 350 /**
 351  * nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
 352  * @info: pointer to NLMPROC_SM_NOTIFY arguments
 353  *
 354  * Returns a matching nsm_handle if found in the nsm cache. The returned
 355  * nsm_handle's reference count is bumped. Otherwise returns NULL if some
 356  * error occurred.
 357  */
 358 struct nsm_handle *nsm_reboot_lookup(const struct nlm_reboot *info)
 359 {
 360         struct nsm_handle *cached;
 361
 362         spin_lock(&nsm_lock);
 363
 364         cached = nsm_lookup_priv(&info->priv);
 365         if (unlikely(cached == NULL)) {
 366                 spin_unlock(&nsm_lock);
 367                 dprintk("lockd: never saw rebooted peer '%.*s' before\n",
 368                                 info->len, info->mon);
 369                 return cached;
 370         }
 371
 372         atomic_inc(&cached->sm_count);
 373         spin_unlock(&nsm_lock);
 374
 375         dprintk("lockd: host %s (%s) rebooted, cnt %d\n",
 376                         cached->sm_name, cached->sm_addrbuf,
 377                         atomic_read(&cached->sm_count));
 378         return cached;
 379 }
 380
 381 /**
 382  * nsm_release - Release an NSM handle
 383  * @nsm: pointer to handle to be released
 384  *
 385  */
 386 void nsm_release(struct nsm_handle *nsm)
 387 {
 388         if (atomic_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
 389                 list_del(&nsm->sm_link);
 390                 spin_unlock(&nsm_lock);
 391                 dprintk("lockd: destroyed nsm_handle for %s (%s)\n",
 392                                 nsm->sm_name, nsm->sm_addrbuf);
 393                 kfree(nsm);
 394         }
 395 }
 396
 397 /*
 398  * XDR functions for NSM.
 399  *
 400  * See http://www.opengroup.org/ for details on the Network
 401  * Status Monitor wire protocol.
 402  */
 403
 404 static int encode_nsm_string(struct xdr_stream *xdr, const char *string)
 405 {
 406         const u32 len = strlen(string);
 407         __be32 *p;
 408
 409         if (unlikely(len > SM_MAXSTRLEN))
 410                 return -EIO;
 411         p = xdr_reserve_space(xdr, sizeof(u32) + len);
 412         if (unlikely(p == NULL))
 413                 return -EIO;
 414         xdr_encode_opaque(p, string, len);
 415         return 0;
 416 }
 417
 418 /*
 419  * "mon_name" specifies the host to be monitored.
 420  */
 421 static int encode_mon_name(struct xdr_stream *xdr, const struct nsm_args *argp)
 422 {
 423         return encode_nsm_string(xdr, argp->mon_name);
 424 }
 425
 426 /*
 427  * The "my_id" argument specifies the hostname and RPC procedure
 428  * to be called when the status manager receives notification
 429  * (via the NLMPROC_SM_NOTIFY call) that the state of host "mon_name"
 430  * has changed.
 431  */
 432 static int encode_my_id(struct xdr_stream *xdr, const struct nsm_args *argp)
 433 {
 434         int status;
 435         __be32 *p;
 436
 437         status = encode_nsm_string(xdr, utsname()->nodename);
 438         if (unlikely(status != 0))
 439                 return status;
 440         p = xdr_reserve_space(xdr, 3 * sizeof(u32));
 441         if (unlikely(p == NULL))
 442                 return -EIO;
 443         *p++ = htonl(argp->prog);
 444         *p++ = htonl(argp->vers);
 445         *p++ = htonl(argp->proc);
 446         return 0;
 447 }
 448
 449 /*
 450  * The "mon_id" argument specifies the non-private arguments
 451  * of an NSMPROC_MON or NSMPROC_UNMON call.
 452  */
 453 static int encode_mon_id(struct xdr_stream *xdr, const struct nsm_args *argp)
 454 {
 455         int status;
 456
 457         status = encode_mon_name(xdr, argp);
 458         if (unlikely(status != 0))
 459                 return status;
 460         return encode_my_id(xdr, argp);
 461 }
 462
 463 /*
 464  * The "priv" argument may contain private information required
 465  * by the NSMPROC_MON call. This information will be supplied in the
 466  * NLMPROC_SM_NOTIFY call.
 467  */
 468 static int encode_priv(struct xdr_stream *xdr, const struct nsm_args *argp)
 469 {
 470         __be32 *p;
 471
 472         p = xdr_reserve_space(xdr, SM_PRIV_SIZE);
 473         if (unlikely(p == NULL))
 474                 return -EIO;
 475         xdr_encode_opaque_fixed(p, argp->priv->data, SM_PRIV_SIZE);
 476         return 0;
 477 }
 478
 479 static int xdr_enc_mon(struct rpc_rqst *req, __be32 *p,
 480                        const struct nsm_args *argp)
 481 {
 482         struct xdr_stream xdr;
 483         int status;
 484
 485         xdr_init_encode(&xdr, &req->rq_snd_buf, p);
 486         status = encode_mon_id(&xdr, argp);
 487         if (unlikely(status))
 488                 return status;
 489         return encode_priv(&xdr, argp);
 490 }
 491
 492 static int xdr_enc_unmon(struct rpc_rqst *req, __be32 *p,
 493                          const struct nsm_args *argp)
 494 {
 495         struct xdr_stream xdr;
 496
 497         xdr_init_encode(&xdr, &req->rq_snd_buf, p);
 498         return encode_mon_id(&xdr, argp);
 499 }
 500
 501 static int xdr_dec_stat_res(struct rpc_rqst *rqstp, __be32 *p,
 502                             struct nsm_res *resp)
 503 {
 504         struct xdr_stream xdr;
 505
 506         xdr_init_decode(&xdr, &rqstp->rq_rcv_buf, p);
 507         p = xdr_inline_decode(&xdr, 2 * sizeof(u32));
 508         if (unlikely(p == NULL))
 509                 return -EIO;
 510         resp->status = ntohl(*p++);
 511         resp->state = ntohl(*p);
 512
 513         dprintk("lockd: xdr_dec_stat_res status %d state %d\n",
 514                         resp->status, resp->state);
 515         return 0;
 516 }
 517
 518 static int xdr_dec_stat(struct rpc_rqst *rqstp, __be32 *p,
 519                         struct nsm_res *resp)
 520 {
 521         struct xdr_stream xdr;
 522
 523         xdr_init_decode(&xdr, &rqstp->rq_rcv_buf, p);
 524         p = xdr_inline_decode(&xdr, sizeof(u32));
 525         if (unlikely(p == NULL))
 526                 return -EIO;
 527         resp->state = ntohl(*p);
 528
 529         dprintk("lockd: xdr_dec_stat state %d\n", resp->state);
 530         return 0;
 531 }
 532
 533 #define SM_my_name_sz   (1+XDR_QUADLEN(SM_MAXSTRLEN))
 534 #define SM_my_id_sz     (SM_my_name_sz+3)
 535 #define SM_mon_name_sz  (1+XDR_QUADLEN(SM_MAXSTRLEN))
 536 #define SM_mon_id_sz    (SM_mon_name_sz+SM_my_id_sz)
 537 #define SM_priv_sz      (XDR_QUADLEN(SM_PRIV_SIZE))
 538 #define SM_mon_sz       (SM_mon_id_sz+SM_priv_sz)
 539 #define SM_monres_sz    2
 540 #define SM_unmonres_sz  1
 541
 542 static struct rpc_procinfo      nsm_procedures[] = {
 543 [NSMPROC_MON] = {
 544                 .p_proc         = NSMPROC_MON,
 545                 .p_encode       = (kxdrproc_t)xdr_enc_mon,
 546                 .p_decode       = (kxdrproc_t)xdr_dec_stat_res,
 547                 .p_arglen       = SM_mon_sz,
 548                 .p_replen       = SM_monres_sz,
 549                 .p_statidx      = NSMPROC_MON,
 550                 .p_name         = "MONITOR",
 551         },
 552 [NSMPROC_UNMON] = {
 553                 .p_proc         = NSMPROC_UNMON,
 554                 .p_encode       = (kxdrproc_t)xdr_enc_unmon,
 555                 .p_decode       = (kxdrproc_t)xdr_dec_stat,
 556                 .p_arglen       = SM_mon_id_sz,
 557                 .p_replen       = SM_unmonres_sz,
 558                 .p_statidx      = NSMPROC_UNMON,
 559                 .p_name         = "UNMONITOR",
 560         },
 561 };
 562
 563 static struct rpc_version       nsm_version1 = {
 564                 .number         = 1,
 565                 .nrprocs        = ARRAY_SIZE(nsm_procedures),
 566                 .procs          = nsm_procedures
 567 };
 568
 569 static struct rpc_version *     nsm_version[] = {
 570         [1] = &nsm_version1,
 571 };
 572
 573 static struct rpc_stat          nsm_stats;
 574
 575 static struct rpc_program       nsm_program = {
 576                 .name           = "statd",
 577                 .number         = NSM_PROGRAM,
 578                 .nrvers         = ARRAY_SIZE(nsm_version),
 579                 .version        = nsm_version,
 580                 .stats          = &nsm_stats
 581 };