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 const 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 bool    __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(struct net *net)
  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                    = 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                          struct net *net)
  88 {
  89         struct rpc_clnt *clnt;
  90         int             status;
  91         struct nsm_args args = {
  92                 .priv           = &nsm->sm_priv,
  93                 .prog           = NLM_PROGRAM,
  94                 .vers           = 3,
  95                 .proc           = NLMPROC_NSM_NOTIFY,
  96                 .mon_name       = nsm->sm_mon_name,
  97         };
  98         struct rpc_message msg = {
  99                 .rpc_argp       = &args,
 100                 .rpc_resp       = res,
 101         };
 102
 103         clnt = nsm_create(net);
 104         if (IS_ERR(clnt)) {
 105                 status = PTR_ERR(clnt);
 106                 dprintk("lockd: failed to create NSM upcall transport, "
 107                                 "status=%d\n", status);
 108                 goto out;
 109         }
 110
 111         memset(res, 0, sizeof(*res));
 112
 113         msg.rpc_proc = &clnt->cl_procinfo[proc];
 114         status = rpc_call_sync(clnt, &msg, 0);
 115         if (status < 0)
 116                 dprintk("lockd: NSM upcall RPC failed, status=%d\n",
 117                                 status);
 118         else
 119                 status = 0;
 120         rpc_shutdown_client(clnt);
 121  out:
 122         return status;
 123 }
 124
 125 /**
 126  * nsm_monitor - Notify a peer in case we reboot
 127  * @host: pointer to nlm_host of peer to notify
 128  *
 129  * If this peer is not already monitored, this function sends an
 130  * upcall to the local rpc.statd to record the name/address of
 131  * the peer to notify in case we reboot.
 132  *
 133  * Returns zero if the peer is monitored by the local rpc.statd;
 134  * otherwise a negative errno value is returned.
 135  */
 136 int nsm_monitor(const struct nlm_host *host)
 137 {
 138         struct nsm_handle *nsm = host->h_nsmhandle;
 139         struct nsm_res  res;
 140         int             status;
 141
 142         dprintk("lockd: nsm_monitor(%s)\n", nsm->sm_name);
 143
 144         if (nsm->sm_monitored)
 145                 return 0;
 146
 147         /*
 148          * Choose whether to record the caller_name or IP address of
 149          * this peer in the local rpc.statd's database.
 150          */
 151         nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf;
 152
 153         status = nsm_mon_unmon(nsm, NSMPROC_MON, &res, host->net);
 154         if (unlikely(res.status != 0))
 155                 status = -EIO;
 156         if (unlikely(status < 0)) {
 157                 printk(KERN_NOTICE "lockd: cannot monitor %s\n", nsm->sm_name);
 158                 return status;
 159         }
 160
 161         nsm->sm_monitored = 1;
 162         if (unlikely(nsm_local_state != res.state)) {
 163                 nsm_local_state = res.state;
 164                 dprintk("lockd: NSM state changed to %d\n", nsm_local_state);
 165         }
 166         return 0;
 167 }
 168
 169 /**
 170  * nsm_unmonitor - Unregister peer notification
 171  * @host: pointer to nlm_host of peer to stop monitoring
 172  *
 173  * If this peer is monitored, this function sends an upcall to
 174  * tell the local rpc.statd not to send this peer a notification
 175  * when we reboot.
 176  */
 177 void nsm_unmonitor(const struct nlm_host *host)
 178 {
 179         struct nsm_handle *nsm = host->h_nsmhandle;
 180         struct nsm_res  res;
 181         int status;
 182
 183         if (atomic_read(&nsm->sm_count) == 1
 184          && nsm->sm_monitored && !nsm->sm_sticky) {
 185                 dprintk("lockd: nsm_unmonitor(%s)\n", nsm->sm_name);
 186
 187                 status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res, host->net);
 188                 if (res.status != 0)
 189                         status = -EIO;
 190                 if (status < 0)
 191                         printk(KERN_NOTICE "lockd: cannot unmonitor %s\n",
 192                                         nsm->sm_name);
 193                 else
 194                         nsm->sm_monitored = 0;
 195         }
 196 }
 197
 198 static struct nsm_handle *nsm_lookup_hostname(const char *hostname,
 199                                               const size_t len)
 200 {
 201         struct nsm_handle *nsm;
 202
 203         list_for_each_entry(nsm, &nsm_handles, sm_link)
 204                 if (strlen(nsm->sm_name) == len &&
 205                     memcmp(nsm->sm_name, hostname, len) == 0)
 206                         return nsm;
 207         return NULL;
 208 }
 209
 210 static struct nsm_handle *nsm_lookup_addr(const struct sockaddr *sap)
 211 {
 212         struct nsm_handle *nsm;
 213
 214         list_for_each_entry(nsm, &nsm_handles, sm_link)
 215                 if (rpc_cmp_addr(nsm_addr(nsm), sap))
 216                         return nsm;
 217         return NULL;
 218 }
 219
 220 static struct nsm_handle *nsm_lookup_priv(const struct nsm_private *priv)
 221 {
 222         struct nsm_handle *nsm;
 223
 224         list_for_each_entry(nsm, &nsm_handles, sm_link)
 225                 if (memcmp(nsm->sm_priv.data, priv->data,
 226                                         sizeof(priv->data)) == 0)
 227                         return nsm;
 228         return NULL;
 229 }
 230
 231 /*
 232  * Construct a unique cookie to match this nsm_handle to this monitored
 233  * host.  It is passed to the local rpc.statd via NSMPROC_MON, and
 234  * returned via NLMPROC_SM_NOTIFY, in the "priv" field of these
 235  * requests.
 236  *
 237  * The NSM protocol requires that these cookies be unique while the
 238  * system is running.  We prefer a stronger requirement of making them
 239  * unique across reboots.  If user space bugs cause a stale cookie to
 240  * be sent to the kernel, it could cause the wrong host to lose its
 241  * lock state if cookies were not unique across reboots.
 242  *
 243  * The cookies are exposed only to local user space via loopback.  They
 244  * do not appear on the physical network.  If we want greater security
 245  * for some reason, nsm_init_private() could perform a one-way hash to
 246  * obscure the contents of the cookie.
 247  */
 248 static void nsm_init_private(struct nsm_handle *nsm)
 249 {
 250         u64 *p = (u64 *)&nsm->sm_priv.data;
 251         struct timespec ts;
 252         s64 ns;
 253
 254         ktime_get_ts(&ts);
 255         ns = timespec_to_ns(&ts);
 256         put_unaligned(ns, p);
 257         put_unaligned((unsigned long)nsm, p + 1);
 258 }
 259
 260 static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
 261                                             const size_t salen,
 262                                             const char *hostname,
 263                                             const size_t hostname_len)
 264 {
 265         struct nsm_handle *new;
 266
 267         new = kzalloc(sizeof(*new) + hostname_len + 1, GFP_KERNEL);
 268         if (unlikely(new == NULL))
 269                 return NULL;
 270
 271         atomic_set(&new->sm_count, 1);
 272         new->sm_name = (char *)(new + 1);
 273         memcpy(nsm_addr(new), sap, salen);
 274         new->sm_addrlen = salen;
 275         nsm_init_private(new);
 276
 277         if (rpc_ntop(nsm_addr(new), new->sm_addrbuf,
 278                                         sizeof(new->sm_addrbuf)) == 0)
 279                 (void)snprintf(new->sm_addrbuf, sizeof(new->sm_addrbuf),
 280                                 "unsupported address family");
 281         memcpy(new->sm_name, hostname, hostname_len);
 282         new->sm_name[hostname_len] = '\0';
 283
 284         return new;
 285 }
 286
 287 /**
 288  * nsm_get_handle - Find or create a cached nsm_handle
 289  * @sap: pointer to socket address of handle to find
 290  * @salen: length of socket address
 291  * @hostname: pointer to C string containing hostname to find
 292  * @hostname_len: length of C string
 293  *
 294  * Behavior is modulated by the global nsm_use_hostnames variable.
 295  *
 296  * Returns a cached nsm_handle after bumping its ref count, or
 297  * returns a fresh nsm_handle if a handle that matches @sap and/or
 298  * @hostname cannot be found in the handle cache.  Returns NULL if
 299  * an error occurs.
 300  */
 301 struct nsm_handle *nsm_get_handle(const struct sockaddr *sap,
 302                                   const size_t salen, const char *hostname,
 303                                   const size_t hostname_len)
 304 {
 305         struct nsm_handle *cached, *new = NULL;
 306
 307         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 308                 if (printk_ratelimit()) {
 309                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 310                                             "in NFS lock request\n",
 311                                 (int)hostname_len, hostname);
 312                 }
 313                 return NULL;
 314         }
 315
 316 retry:
 317         spin_lock(&nsm_lock);
 318
 319         if (nsm_use_hostnames && hostname != NULL)
 320                 cached = nsm_lookup_hostname(hostname, hostname_len);
 321         else
 322                 cached = nsm_lookup_addr(sap);
 323
 324         if (cached != NULL) {
 325                 atomic_inc(&cached->sm_count);
 326                 spin_unlock(&nsm_lock);
 327                 kfree(new);
 328                 dprintk("lockd: found nsm_handle for %s (%s), "
 329                                 "cnt %d\n", cached->sm_name,
 330                                 cached->sm_addrbuf,
 331                                 atomic_read(&cached->sm_count));
 332                 return cached;
 333         }
 334
 335         if (new != NULL) {
 336                 list_add(&new->sm_link, &nsm_handles);
 337                 spin_unlock(&nsm_lock);
 338                 dprintk("lockd: created nsm_handle for %s (%s)\n",
 339                                 new->sm_name, new->sm_addrbuf);
 340                 return new;
 341         }
 342
 343         spin_unlock(&nsm_lock);
 344
 345         new = nsm_create_handle(sap, salen, hostname, hostname_len);
 346         if (unlikely(new == NULL))
 347                 return NULL;
 348         goto retry;
 349 }
 350
 351 /**
 352  * nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
 353  * @info: pointer to NLMPROC_SM_NOTIFY arguments
 354  *
 355  * Returns a matching nsm_handle if found in the nsm cache. The returned
 356  * nsm_handle's reference count is bumped. Otherwise returns NULL if some
 357  * error occurred.
 358  */
 359 struct nsm_handle *nsm_reboot_lookup(const struct nlm_reboot *info)
 360 {
 361         struct nsm_handle *cached;
 362
 363         spin_lock(&nsm_lock);
 364
 365         cached = nsm_lookup_priv(&info->priv);
 366         if (unlikely(cached == NULL)) {
 367                 spin_unlock(&nsm_lock);
 368                 dprintk("lockd: never saw rebooted peer '%.*s' before\n",
 369                                 info->len, info->mon);
 370                 return cached;
 371         }
 372
 373         atomic_inc(&cached->sm_count);
 374         spin_unlock(&nsm_lock);
 375
 376         dprintk("lockd: host %s (%s) rebooted, cnt %d\n",
 377                         cached->sm_name, cached->sm_addrbuf,
 378                         atomic_read(&cached->sm_count));
 379         return cached;
 380 }
 381
 382 /**
 383  * nsm_release - Release an NSM handle
 384  * @nsm: pointer to handle to be released
 385  *
 386  */
 387 void nsm_release(struct nsm_handle *nsm)
 388 {
 389         if (atomic_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
 390                 list_del(&nsm->sm_link);
 391                 spin_unlock(&nsm_lock);
 392                 dprintk("lockd: destroyed nsm_handle for %s (%s)\n",
 393                                 nsm->sm_name, nsm->sm_addrbuf);
 394                 kfree(nsm);
 395         }
 396 }
 397
 398 /*
 399  * XDR functions for NSM.
 400  *
 401  * See http://www.opengroup.org/ for details on the Network
 402  * Status Monitor wire protocol.
 403  */
 404
 405 static void encode_nsm_string(struct xdr_stream *xdr, const char *string)
 406 {
 407         const u32 len = strlen(string);
 408         __be32 *p;
 409
 410         BUG_ON(len > SM_MAXSTRLEN);
 411         p = xdr_reserve_space(xdr, 4 + len);
 412         xdr_encode_opaque(p, string, len);
 413 }
 414
 415 /*
 416  * "mon_name" specifies the host to be monitored.
 417  */
 418 static void encode_mon_name(struct xdr_stream *xdr, const struct nsm_args *argp)
 419 {
 420         encode_nsm_string(xdr, argp->mon_name);
 421 }
 422
 423 /*
 424  * The "my_id" argument specifies the hostname and RPC procedure
 425  * to be called when the status manager receives notification
 426  * (via the NLMPROC_SM_NOTIFY call) that the state of host "mon_name"
 427  * has changed.
 428  */
 429 static void encode_my_id(struct xdr_stream *xdr, const struct nsm_args *argp)
 430 {
 431         __be32 *p;
 432
 433         encode_nsm_string(xdr, utsname()->nodename);
 434         p = xdr_reserve_space(xdr, 4 + 4 + 4);
 435         *p++ = cpu_to_be32(argp->prog);
 436         *p++ = cpu_to_be32(argp->vers);
 437         *p = cpu_to_be32(argp->proc);
 438 }
 439
 440 /*
 441  * The "mon_id" argument specifies the non-private arguments
 442  * of an NSMPROC_MON or NSMPROC_UNMON call.
 443  */
 444 static void encode_mon_id(struct xdr_stream *xdr, const struct nsm_args *argp)
 445 {
 446         encode_mon_name(xdr, argp);
 447         encode_my_id(xdr, argp);
 448 }
 449
 450 /*
 451  * The "priv" argument may contain private information required
 452  * by the NSMPROC_MON call. This information will be supplied in the
 453  * NLMPROC_SM_NOTIFY call.
 454  */
 455 static void encode_priv(struct xdr_stream *xdr, const struct nsm_args *argp)
 456 {
 457         __be32 *p;
 458
 459         p = xdr_reserve_space(xdr, SM_PRIV_SIZE);
 460         xdr_encode_opaque_fixed(p, argp->priv->data, SM_PRIV_SIZE);
 461 }
 462
 463 static void nsm_xdr_enc_mon(struct rpc_rqst *req, struct xdr_stream *xdr,
 464                             const struct nsm_args *argp)
 465 {
 466         encode_mon_id(xdr, argp);
 467         encode_priv(xdr, argp);
 468 }
 469
 470 static void nsm_xdr_enc_unmon(struct rpc_rqst *req, struct xdr_stream *xdr,
 471                               const struct nsm_args *argp)
 472 {
 473         encode_mon_id(xdr, argp);
 474 }
 475
 476 static int nsm_xdr_dec_stat_res(struct rpc_rqst *rqstp,
 477                                 struct xdr_stream *xdr,
 478                                 struct nsm_res *resp)
 479 {
 480         __be32 *p;
 481
 482         p = xdr_inline_decode(xdr, 4 + 4);
 483         if (unlikely(p == NULL))
 484                 return -EIO;
 485         resp->status = be32_to_cpup(p++);
 486         resp->state = be32_to_cpup(p);
 487
 488         dprintk("lockd: %s status %d state %d\n",
 489                 __func__, resp->status, resp->state);
 490         return 0;
 491 }
 492
 493 static int nsm_xdr_dec_stat(struct rpc_rqst *rqstp,
 494                             struct xdr_stream *xdr,
 495                             struct nsm_res *resp)
 496 {
 497         __be32 *p;
 498
 499         p = xdr_inline_decode(xdr, 4);
 500         if (unlikely(p == NULL))
 501                 return -EIO;
 502         resp->state = be32_to_cpup(p);
 503
 504         dprintk("lockd: %s state %d\n", __func__, resp->state);
 505         return 0;
 506 }
 507
 508 #define SM_my_name_sz   (1+XDR_QUADLEN(SM_MAXSTRLEN))
 509 #define SM_my_id_sz     (SM_my_name_sz+3)
 510 #define SM_mon_name_sz  (1+XDR_QUADLEN(SM_MAXSTRLEN))
 511 #define SM_mon_id_sz    (SM_mon_name_sz+SM_my_id_sz)
 512 #define SM_priv_sz      (XDR_QUADLEN(SM_PRIV_SIZE))
 513 #define SM_mon_sz       (SM_mon_id_sz+SM_priv_sz)
 514 #define SM_monres_sz    2
 515 #define SM_unmonres_sz  1
 516
 517 static struct rpc_procinfo      nsm_procedures[] = {
 518 [NSMPROC_MON] = {
 519                 .p_proc         = NSMPROC_MON,
 520                 .p_encode       = (kxdreproc_t)nsm_xdr_enc_mon,
 521                 .p_decode       = (kxdrdproc_t)nsm_xdr_dec_stat_res,
 522                 .p_arglen       = SM_mon_sz,
 523                 .p_replen       = SM_monres_sz,
 524                 .p_statidx      = NSMPROC_MON,
 525                 .p_name         = "MONITOR",
 526         },
 527 [NSMPROC_UNMON] = {
 528                 .p_proc         = NSMPROC_UNMON,
 529                 .p_encode       = (kxdreproc_t)nsm_xdr_enc_unmon,
 530                 .p_decode       = (kxdrdproc_t)nsm_xdr_dec_stat,
 531                 .p_arglen       = SM_mon_id_sz,
 532                 .p_replen       = SM_unmonres_sz,
 533                 .p_statidx      = NSMPROC_UNMON,
 534                 .p_name         = "UNMONITOR",
 535         },
 536 };
 537
 538 static const struct rpc_version nsm_version1 = {
 539                 .number         = 1,
 540                 .nrprocs        = ARRAY_SIZE(nsm_procedures),
 541                 .procs          = nsm_procedures
 542 };
 543
 544 static const struct rpc_version *nsm_version[] = {
 545         [1] = &nsm_version1,
 546 };
 547
 548 static struct rpc_stat          nsm_stats;
 549
 550 static const struct rpc_program nsm_program = {
 551                 .name           = "statd",
 552                 .number         = NSM_PROGRAM,
 553                 .nrvers         = ARRAY_SIZE(nsm_version),
 554                 .version        = nsm_version,
 555                 .stats          = &nsm_stats
 556 };