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