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/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
  26enum {
  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
  36struct 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
  45struct nsm_res {
  46        u32                     status;
  47        u32                     state;
  48};
  49
  50static const struct rpc_program nsm_program;
  51static                          LIST_HEAD(nsm_handles);
  52static                          DEFINE_SPINLOCK(nsm_lock);
  53
  54/*
  55 * Local NSM state
  56 */
  57u32     __read_mostly           nsm_local_state;
  58bool    __read_mostly           nsm_use_hostnames;
  59
  60static inline struct sockaddr *nsm_addr(const struct nsm_handle *nsm)
  61{
  62        return (struct sockaddr *)&nsm->sm_addr;
  63}
  64
  65static 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
  86static 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 */
 136int 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 */
 177void 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
 198static 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
 210static 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
 220static 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 */
 248static 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
 260static 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 */
 301struct 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
 316retry:
 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 */
 359struct 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 */
 387void 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
 405static 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 */
 418static 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 */
 429static 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 */
 444static 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 */
 455static 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
 463static 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
 470static 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
 476static 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
 493static 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
 517static 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
 538static const struct rpc_version nsm_version1 = {
 539                .number         = 1,
 540                .nrprocs        = ARRAY_SIZE(nsm_procedures),
 541                .procs          = nsm_procedures
 542};
 543
 544static const struct rpc_version *nsm_version[] = {
 545        [1] = &nsm_version1,
 546};
 547
 548static struct rpc_stat          nsm_stats;
 549
 550static 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};
 557
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