linux/fs/lockd/mon.c
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   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/kernel.h>
  11#include <linux/ktime.h>
  12#include <linux/slab.h>
  13
  14#include <linux/sunrpc/clnt.h>
  15#include <linux/sunrpc/addr.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#include "netns.h"
  23
  24#define NLMDBG_FACILITY         NLMDBG_MONITOR
  25#define NSM_PROGRAM             100024
  26#define NSM_VERSION             1
  27
  28enum {
  29        NSMPROC_NULL,
  30        NSMPROC_STAT,
  31        NSMPROC_MON,
  32        NSMPROC_UNMON,
  33        NSMPROC_UNMON_ALL,
  34        NSMPROC_SIMU_CRASH,
  35        NSMPROC_NOTIFY,
  36};
  37
  38struct nsm_args {
  39        struct nsm_private      *priv;
  40        u32                     prog;           /* RPC callback info */
  41        u32                     vers;
  42        u32                     proc;
  43
  44        char                    *mon_name;
  45        char                    *nodename;
  46};
  47
  48struct nsm_res {
  49        u32                     status;
  50        u32                     state;
  51};
  52
  53static const struct rpc_program nsm_program;
  54static                          LIST_HEAD(nsm_handles);
  55static                          DEFINE_SPINLOCK(nsm_lock);
  56
  57/*
  58 * Local NSM state
  59 */
  60u32     __read_mostly           nsm_local_state;
  61bool    __read_mostly           nsm_use_hostnames;
  62
  63static inline struct sockaddr *nsm_addr(const struct nsm_handle *nsm)
  64{
  65        return (struct sockaddr *)&nsm->sm_addr;
  66}
  67
  68static struct rpc_clnt *nsm_create(struct net *net)
  69{
  70        struct sockaddr_in sin = {
  71                .sin_family             = AF_INET,
  72                .sin_addr.s_addr        = htonl(INADDR_LOOPBACK),
  73        };
  74        struct rpc_create_args args = {
  75                .net                    = net,
  76                .protocol               = XPRT_TRANSPORT_TCP,
  77                .address                = (struct sockaddr *)&sin,
  78                .addrsize               = sizeof(sin),
  79                .servername             = "rpc.statd",
  80                .program                = &nsm_program,
  81                .version                = NSM_VERSION,
  82                .authflavor             = RPC_AUTH_NULL,
  83                .flags                  = RPC_CLNT_CREATE_NOPING,
  84        };
  85
  86        return rpc_create(&args);
  87}
  88
  89static struct rpc_clnt *nsm_client_set(struct lockd_net *ln,
  90                struct rpc_clnt *clnt)
  91{
  92        spin_lock(&ln->nsm_clnt_lock);
  93        if (ln->nsm_users == 0) {
  94                if (clnt == NULL)
  95                        goto out;
  96                ln->nsm_clnt = clnt;
  97        }
  98        clnt = ln->nsm_clnt;
  99        ln->nsm_users++;
 100out:
 101        spin_unlock(&ln->nsm_clnt_lock);
 102        return clnt;
 103}
 104
 105static struct rpc_clnt *nsm_client_get(struct net *net)
 106{
 107        struct rpc_clnt *clnt, *new;
 108        struct lockd_net *ln = net_generic(net, lockd_net_id);
 109
 110        clnt = nsm_client_set(ln, NULL);
 111        if (clnt != NULL)
 112                goto out;
 113
 114        clnt = new = nsm_create(net);
 115        if (IS_ERR(clnt))
 116                goto out;
 117
 118        clnt = nsm_client_set(ln, new);
 119        if (clnt != new)
 120                rpc_shutdown_client(new);
 121out:
 122        return clnt;
 123}
 124
 125static void nsm_client_put(struct net *net)
 126{
 127        struct lockd_net *ln = net_generic(net, lockd_net_id);
 128        struct rpc_clnt *clnt = NULL;
 129
 130        spin_lock(&ln->nsm_clnt_lock);
 131        ln->nsm_users--;
 132        if (ln->nsm_users == 0) {
 133                clnt = ln->nsm_clnt;
 134                ln->nsm_clnt = NULL;
 135        }
 136        spin_unlock(&ln->nsm_clnt_lock);
 137        if (clnt != NULL)
 138                rpc_shutdown_client(clnt);
 139}
 140
 141static int nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res,
 142                         struct rpc_clnt *clnt)
 143{
 144        int             status;
 145        struct nsm_args args = {
 146                .priv           = &nsm->sm_priv,
 147                .prog           = NLM_PROGRAM,
 148                .vers           = 3,
 149                .proc           = NLMPROC_NSM_NOTIFY,
 150                .mon_name       = nsm->sm_mon_name,
 151                .nodename       = clnt->cl_nodename,
 152        };
 153        struct rpc_message msg = {
 154                .rpc_argp       = &args,
 155                .rpc_resp       = res,
 156        };
 157
 158        memset(res, 0, sizeof(*res));
 159
 160        msg.rpc_proc = &clnt->cl_procinfo[proc];
 161        status = rpc_call_sync(clnt, &msg, RPC_TASK_SOFTCONN);
 162        if (status < 0)
 163                dprintk("lockd: NSM upcall RPC failed, status=%d\n",
 164                                status);
 165        else
 166                status = 0;
 167        return status;
 168}
 169
 170/**
 171 * nsm_monitor - Notify a peer in case we reboot
 172 * @host: pointer to nlm_host of peer to notify
 173 *
 174 * If this peer is not already monitored, this function sends an
 175 * upcall to the local rpc.statd to record the name/address of
 176 * the peer to notify in case we reboot.
 177 *
 178 * Returns zero if the peer is monitored by the local rpc.statd;
 179 * otherwise a negative errno value is returned.
 180 */
 181int nsm_monitor(const struct nlm_host *host)
 182{
 183        struct nsm_handle *nsm = host->h_nsmhandle;
 184        struct nsm_res  res;
 185        int             status;
 186        struct rpc_clnt *clnt;
 187
 188        dprintk("lockd: nsm_monitor(%s)\n", nsm->sm_name);
 189
 190        if (nsm->sm_monitored)
 191                return 0;
 192
 193        /*
 194         * Choose whether to record the caller_name or IP address of
 195         * this peer in the local rpc.statd's database.
 196         */
 197        nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf;
 198
 199        clnt = nsm_client_get(host->net);
 200        if (IS_ERR(clnt)) {
 201                status = PTR_ERR(clnt);
 202                dprintk("lockd: failed to create NSM upcall transport, "
 203                                "status=%d, net=%p\n", status, host->net);
 204                return status;
 205        }
 206
 207        status = nsm_mon_unmon(nsm, NSMPROC_MON, &res, clnt);
 208        if (unlikely(res.status != 0))
 209                status = -EIO;
 210        if (unlikely(status < 0)) {
 211                printk(KERN_NOTICE "lockd: cannot monitor %s\n", nsm->sm_name);
 212                return status;
 213        }
 214
 215        nsm->sm_monitored = 1;
 216        if (unlikely(nsm_local_state != res.state)) {
 217                nsm_local_state = res.state;
 218                dprintk("lockd: NSM state changed to %d\n", nsm_local_state);
 219        }
 220        return 0;
 221}
 222
 223/**
 224 * nsm_unmonitor - Unregister peer notification
 225 * @host: pointer to nlm_host of peer to stop monitoring
 226 *
 227 * If this peer is monitored, this function sends an upcall to
 228 * tell the local rpc.statd not to send this peer a notification
 229 * when we reboot.
 230 */
 231void nsm_unmonitor(const struct nlm_host *host)
 232{
 233        struct nsm_handle *nsm = host->h_nsmhandle;
 234        struct nsm_res  res;
 235        int status;
 236
 237        if (atomic_read(&nsm->sm_count) == 1
 238         && nsm->sm_monitored && !nsm->sm_sticky) {
 239                struct lockd_net *ln = net_generic(host->net, lockd_net_id);
 240
 241                dprintk("lockd: nsm_unmonitor(%s)\n", nsm->sm_name);
 242
 243                status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res, ln->nsm_clnt);
 244                if (res.status != 0)
 245                        status = -EIO;
 246                if (status < 0)
 247                        printk(KERN_NOTICE "lockd: cannot unmonitor %s\n",
 248                                        nsm->sm_name);
 249                else
 250                        nsm->sm_monitored = 0;
 251
 252                nsm_client_put(host->net);
 253        }
 254}
 255
 256static struct nsm_handle *nsm_lookup_hostname(const char *hostname,
 257                                              const size_t len)
 258{
 259        struct nsm_handle *nsm;
 260
 261        list_for_each_entry(nsm, &nsm_handles, sm_link)
 262                if (strlen(nsm->sm_name) == len &&
 263                    memcmp(nsm->sm_name, hostname, len) == 0)
 264                        return nsm;
 265        return NULL;
 266}
 267
 268static struct nsm_handle *nsm_lookup_addr(const struct sockaddr *sap)
 269{
 270        struct nsm_handle *nsm;
 271
 272        list_for_each_entry(nsm, &nsm_handles, sm_link)
 273                if (rpc_cmp_addr(nsm_addr(nsm), sap))
 274                        return nsm;
 275        return NULL;
 276}
 277
 278static struct nsm_handle *nsm_lookup_priv(const struct nsm_private *priv)
 279{
 280        struct nsm_handle *nsm;
 281
 282        list_for_each_entry(nsm, &nsm_handles, sm_link)
 283                if (memcmp(nsm->sm_priv.data, priv->data,
 284                                        sizeof(priv->data)) == 0)
 285                        return nsm;
 286        return NULL;
 287}
 288
 289/*
 290 * Construct a unique cookie to match this nsm_handle to this monitored
 291 * host.  It is passed to the local rpc.statd via NSMPROC_MON, and
 292 * returned via NLMPROC_SM_NOTIFY, in the "priv" field of these
 293 * requests.
 294 *
 295 * The NSM protocol requires that these cookies be unique while the
 296 * system is running.  We prefer a stronger requirement of making them
 297 * unique across reboots.  If user space bugs cause a stale cookie to
 298 * be sent to the kernel, it could cause the wrong host to lose its
 299 * lock state if cookies were not unique across reboots.
 300 *
 301 * The cookies are exposed only to local user space via loopback.  They
 302 * do not appear on the physical network.  If we want greater security
 303 * for some reason, nsm_init_private() could perform a one-way hash to
 304 * obscure the contents of the cookie.
 305 */
 306static void nsm_init_private(struct nsm_handle *nsm)
 307{
 308        u64 *p = (u64 *)&nsm->sm_priv.data;
 309        struct timespec ts;
 310        s64 ns;
 311
 312        ktime_get_ts(&ts);
 313        ns = timespec_to_ns(&ts);
 314        put_unaligned(ns, p);
 315        put_unaligned((unsigned long)nsm, p + 1);
 316}
 317
 318static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
 319                                            const size_t salen,
 320                                            const char *hostname,
 321                                            const size_t hostname_len)
 322{
 323        struct nsm_handle *new;
 324
 325        new = kzalloc(sizeof(*new) + hostname_len + 1, GFP_KERNEL);
 326        if (unlikely(new == NULL))
 327                return NULL;
 328
 329        atomic_set(&new->sm_count, 1);
 330        new->sm_name = (char *)(new + 1);
 331        memcpy(nsm_addr(new), sap, salen);
 332        new->sm_addrlen = salen;
 333        nsm_init_private(new);
 334
 335        if (rpc_ntop(nsm_addr(new), new->sm_addrbuf,
 336                                        sizeof(new->sm_addrbuf)) == 0)
 337                (void)snprintf(new->sm_addrbuf, sizeof(new->sm_addrbuf),
 338                                "unsupported address family");
 339        memcpy(new->sm_name, hostname, hostname_len);
 340        new->sm_name[hostname_len] = '\0';
 341
 342        return new;
 343}
 344
 345/**
 346 * nsm_get_handle - Find or create a cached nsm_handle
 347 * @sap: pointer to socket address of handle to find
 348 * @salen: length of socket address
 349 * @hostname: pointer to C string containing hostname to find
 350 * @hostname_len: length of C string
 351 *
 352 * Behavior is modulated by the global nsm_use_hostnames variable.
 353 *
 354 * Returns a cached nsm_handle after bumping its ref count, or
 355 * returns a fresh nsm_handle if a handle that matches @sap and/or
 356 * @hostname cannot be found in the handle cache.  Returns NULL if
 357 * an error occurs.
 358 */
 359struct nsm_handle *nsm_get_handle(const struct sockaddr *sap,
 360                                  const size_t salen, const char *hostname,
 361                                  const size_t hostname_len)
 362{
 363        struct nsm_handle *cached, *new = NULL;
 364
 365        if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 366                if (printk_ratelimit()) {
 367                        printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 368                                            "in NFS lock request\n",
 369                                (int)hostname_len, hostname);
 370                }
 371                return NULL;
 372        }
 373
 374retry:
 375        spin_lock(&nsm_lock);
 376
 377        if (nsm_use_hostnames && hostname != NULL)
 378                cached = nsm_lookup_hostname(hostname, hostname_len);
 379        else
 380                cached = nsm_lookup_addr(sap);
 381
 382        if (cached != NULL) {
 383                atomic_inc(&cached->sm_count);
 384                spin_unlock(&nsm_lock);
 385                kfree(new);
 386                dprintk("lockd: found nsm_handle for %s (%s), "
 387                                "cnt %d\n", cached->sm_name,
 388                                cached->sm_addrbuf,
 389                                atomic_read(&cached->sm_count));
 390                return cached;
 391        }
 392
 393        if (new != NULL) {
 394                list_add(&new->sm_link, &nsm_handles);
 395                spin_unlock(&nsm_lock);
 396                dprintk("lockd: created nsm_handle for %s (%s)\n",
 397                                new->sm_name, new->sm_addrbuf);
 398                return new;
 399        }
 400
 401        spin_unlock(&nsm_lock);
 402
 403        new = nsm_create_handle(sap, salen, hostname, hostname_len);
 404        if (unlikely(new == NULL))
 405                return NULL;
 406        goto retry;
 407}
 408
 409/**
 410 * nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
 411 * @info: pointer to NLMPROC_SM_NOTIFY arguments
 412 *
 413 * Returns a matching nsm_handle if found in the nsm cache. The returned
 414 * nsm_handle's reference count is bumped. Otherwise returns NULL if some
 415 * error occurred.
 416 */
 417struct nsm_handle *nsm_reboot_lookup(const struct nlm_reboot *info)
 418{
 419        struct nsm_handle *cached;
 420
 421        spin_lock(&nsm_lock);
 422
 423        cached = nsm_lookup_priv(&info->priv);
 424        if (unlikely(cached == NULL)) {
 425                spin_unlock(&nsm_lock);
 426                dprintk("lockd: never saw rebooted peer '%.*s' before\n",
 427                                info->len, info->mon);
 428                return cached;
 429        }
 430
 431        atomic_inc(&cached->sm_count);
 432        spin_unlock(&nsm_lock);
 433
 434        dprintk("lockd: host %s (%s) rebooted, cnt %d\n",
 435                        cached->sm_name, cached->sm_addrbuf,
 436                        atomic_read(&cached->sm_count));
 437        return cached;
 438}
 439
 440/**
 441 * nsm_release - Release an NSM handle
 442 * @nsm: pointer to handle to be released
 443 *
 444 */
 445void nsm_release(struct nsm_handle *nsm)
 446{
 447        if (atomic_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
 448                list_del(&nsm->sm_link);
 449                spin_unlock(&nsm_lock);
 450                dprintk("lockd: destroyed nsm_handle for %s (%s)\n",
 451                                nsm->sm_name, nsm->sm_addrbuf);
 452                kfree(nsm);
 453        }
 454}
 455
 456/*
 457 * XDR functions for NSM.
 458 *
 459 * See http://www.opengroup.org/ for details on the Network
 460 * Status Monitor wire protocol.
 461 */
 462
 463static void encode_nsm_string(struct xdr_stream *xdr, const char *string)
 464{
 465        const u32 len = strlen(string);
 466        __be32 *p;
 467
 468        p = xdr_reserve_space(xdr, 4 + len);
 469        xdr_encode_opaque(p, string, len);
 470}
 471
 472/*
 473 * "mon_name" specifies the host to be monitored.
 474 */
 475static void encode_mon_name(struct xdr_stream *xdr, const struct nsm_args *argp)
 476{
 477        encode_nsm_string(xdr, argp->mon_name);
 478}
 479
 480/*
 481 * The "my_id" argument specifies the hostname and RPC procedure
 482 * to be called when the status manager receives notification
 483 * (via the NLMPROC_SM_NOTIFY call) that the state of host "mon_name"
 484 * has changed.
 485 */
 486static void encode_my_id(struct xdr_stream *xdr, const struct nsm_args *argp)
 487{
 488        __be32 *p;
 489
 490        encode_nsm_string(xdr, argp->nodename);
 491        p = xdr_reserve_space(xdr, 4 + 4 + 4);
 492        *p++ = cpu_to_be32(argp->prog);
 493        *p++ = cpu_to_be32(argp->vers);
 494        *p = cpu_to_be32(argp->proc);
 495}
 496
 497/*
 498 * The "mon_id" argument specifies the non-private arguments
 499 * of an NSMPROC_MON or NSMPROC_UNMON call.
 500 */
 501static void encode_mon_id(struct xdr_stream *xdr, const struct nsm_args *argp)
 502{
 503        encode_mon_name(xdr, argp);
 504        encode_my_id(xdr, argp);
 505}
 506
 507/*
 508 * The "priv" argument may contain private information required
 509 * by the NSMPROC_MON call. This information will be supplied in the
 510 * NLMPROC_SM_NOTIFY call.
 511 */
 512static void encode_priv(struct xdr_stream *xdr, const struct nsm_args *argp)
 513{
 514        __be32 *p;
 515
 516        p = xdr_reserve_space(xdr, SM_PRIV_SIZE);
 517        xdr_encode_opaque_fixed(p, argp->priv->data, SM_PRIV_SIZE);
 518}
 519
 520static void nsm_xdr_enc_mon(struct rpc_rqst *req, struct xdr_stream *xdr,
 521                            const struct nsm_args *argp)
 522{
 523        encode_mon_id(xdr, argp);
 524        encode_priv(xdr, argp);
 525}
 526
 527static void nsm_xdr_enc_unmon(struct rpc_rqst *req, struct xdr_stream *xdr,
 528                              const struct nsm_args *argp)
 529{
 530        encode_mon_id(xdr, argp);
 531}
 532
 533static int nsm_xdr_dec_stat_res(struct rpc_rqst *rqstp,
 534                                struct xdr_stream *xdr,
 535                                struct nsm_res *resp)
 536{
 537        __be32 *p;
 538
 539        p = xdr_inline_decode(xdr, 4 + 4);
 540        if (unlikely(p == NULL))
 541                return -EIO;
 542        resp->status = be32_to_cpup(p++);
 543        resp->state = be32_to_cpup(p);
 544
 545        dprintk("lockd: %s status %d state %d\n",
 546                __func__, resp->status, resp->state);
 547        return 0;
 548}
 549
 550static int nsm_xdr_dec_stat(struct rpc_rqst *rqstp,
 551                            struct xdr_stream *xdr,
 552                            struct nsm_res *resp)
 553{
 554        __be32 *p;
 555
 556        p = xdr_inline_decode(xdr, 4);
 557        if (unlikely(p == NULL))
 558                return -EIO;
 559        resp->state = be32_to_cpup(p);
 560
 561        dprintk("lockd: %s state %d\n", __func__, resp->state);
 562        return 0;
 563}
 564
 565#define SM_my_name_sz   (1+XDR_QUADLEN(SM_MAXSTRLEN))
 566#define SM_my_id_sz     (SM_my_name_sz+3)
 567#define SM_mon_name_sz  (1+XDR_QUADLEN(SM_MAXSTRLEN))
 568#define SM_mon_id_sz    (SM_mon_name_sz+SM_my_id_sz)
 569#define SM_priv_sz      (XDR_QUADLEN(SM_PRIV_SIZE))
 570#define SM_mon_sz       (SM_mon_id_sz+SM_priv_sz)
 571#define SM_monres_sz    2
 572#define SM_unmonres_sz  1
 573
 574static struct rpc_procinfo      nsm_procedures[] = {
 575[NSMPROC_MON] = {
 576                .p_proc         = NSMPROC_MON,
 577                .p_encode       = (kxdreproc_t)nsm_xdr_enc_mon,
 578                .p_decode       = (kxdrdproc_t)nsm_xdr_dec_stat_res,
 579                .p_arglen       = SM_mon_sz,
 580                .p_replen       = SM_monres_sz,
 581                .p_statidx      = NSMPROC_MON,
 582                .p_name         = "MONITOR",
 583        },
 584[NSMPROC_UNMON] = {
 585                .p_proc         = NSMPROC_UNMON,
 586                .p_encode       = (kxdreproc_t)nsm_xdr_enc_unmon,
 587                .p_decode       = (kxdrdproc_t)nsm_xdr_dec_stat,
 588                .p_arglen       = SM_mon_id_sz,
 589                .p_replen       = SM_unmonres_sz,
 590                .p_statidx      = NSMPROC_UNMON,
 591                .p_name         = "UNMONITOR",
 592        },
 593};
 594
 595static const struct rpc_version nsm_version1 = {
 596                .number         = 1,
 597                .nrprocs        = ARRAY_SIZE(nsm_procedures),
 598                .procs          = nsm_procedures
 599};
 600
 601static const struct rpc_version *nsm_version[] = {
 602        [1] = &nsm_version1,
 603};
 604
 605static struct rpc_stat          nsm_stats;
 606
 607static const struct rpc_program nsm_program = {
 608                .name           = "statd",
 609                .number         = NSM_PROGRAM,
 610                .nrvers         = ARRAY_SIZE(nsm_version),
 611                .version        = nsm_version,
 612                .stats          = &nsm_stats
 613};
 614
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