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 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;
  58int     __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(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
  86static 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 */
 135int 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 */
 176void 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
 197static 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
 209static 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
 219static 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 */
 247static 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
 259static 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 */
 300struct 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
 315retry:
 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 */
 358struct 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 */
 386void 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
 404static void encode_nsm_string(struct xdr_stream *xdr, const char *string)
 405{
 406        const u32 len = strlen(string);
 407        __be32 *p;
 408
 409        BUG_ON(len > SM_MAXSTRLEN);
 410        p = xdr_reserve_space(xdr, 4 + len);
 411        xdr_encode_opaque(p, string, len);
 412}
 413
 414/*
 415 * "mon_name" specifies the host to be monitored.
 416 */
 417static void encode_mon_name(struct xdr_stream *xdr, const struct nsm_args *argp)
 418{
 419        encode_nsm_string(xdr, argp->mon_name);
 420}
 421
 422/*
 423 * The "my_id" argument specifies the hostname and RPC procedure
 424 * to be called when the status manager receives notification
 425 * (via the NLMPROC_SM_NOTIFY call) that the state of host "mon_name"
 426 * has changed.
 427 */
 428static void encode_my_id(struct xdr_stream *xdr, const struct nsm_args *argp)
 429{
 430        __be32 *p;
 431
 432        encode_nsm_string(xdr, utsname()->nodename);
 433        p = xdr_reserve_space(xdr, 4 + 4 + 4);
 434        *p++ = cpu_to_be32(argp->prog);
 435        *p++ = cpu_to_be32(argp->vers);
 436        *p = cpu_to_be32(argp->proc);
 437}
 438
 439/*
 440 * The "mon_id" argument specifies the non-private arguments
 441 * of an NSMPROC_MON or NSMPROC_UNMON call.
 442 */
 443static void encode_mon_id(struct xdr_stream *xdr, const struct nsm_args *argp)
 444{
 445        encode_mon_name(xdr, argp);
 446        encode_my_id(xdr, argp);
 447}
 448
 449/*
 450 * The "priv" argument may contain private information required
 451 * by the NSMPROC_MON call. This information will be supplied in the
 452 * NLMPROC_SM_NOTIFY call.
 453 */
 454static void encode_priv(struct xdr_stream *xdr, const struct nsm_args *argp)
 455{
 456        __be32 *p;
 457
 458        p = xdr_reserve_space(xdr, SM_PRIV_SIZE);
 459        xdr_encode_opaque_fixed(p, argp->priv->data, SM_PRIV_SIZE);
 460}
 461
 462static void nsm_xdr_enc_mon(struct rpc_rqst *req, struct xdr_stream *xdr,
 463                            const struct nsm_args *argp)
 464{
 465        encode_mon_id(xdr, argp);
 466        encode_priv(xdr, argp);
 467}
 468
 469static void nsm_xdr_enc_unmon(struct rpc_rqst *req, struct xdr_stream *xdr,
 470                              const struct nsm_args *argp)
 471{
 472        encode_mon_id(xdr, argp);
 473}
 474
 475static int nsm_xdr_dec_stat_res(struct rpc_rqst *rqstp,
 476                                struct xdr_stream *xdr,
 477                                struct nsm_res *resp)
 478{
 479        __be32 *p;
 480
 481        p = xdr_inline_decode(xdr, 4 + 4);
 482        if (unlikely(p == NULL))
 483                return -EIO;
 484        resp->status = be32_to_cpup(p++);
 485        resp->state = be32_to_cpup(p);
 486
 487        dprintk("lockd: %s status %d state %d\n",
 488                __func__, resp->status, resp->state);
 489        return 0;
 490}
 491
 492static int nsm_xdr_dec_stat(struct rpc_rqst *rqstp,
 493                            struct xdr_stream *xdr,
 494                            struct nsm_res *resp)
 495{
 496        __be32 *p;
 497
 498        p = xdr_inline_decode(xdr, 4);
 499        if (unlikely(p == NULL))
 500                return -EIO;
 501        resp->state = be32_to_cpup(p);
 502
 503        dprintk("lockd: %s state %d\n", __func__, resp->state);
 504        return 0;
 505}
 506
 507#define SM_my_name_sz   (1+XDR_QUADLEN(SM_MAXSTRLEN))
 508#define SM_my_id_sz     (SM_my_name_sz+3)
 509#define SM_mon_name_sz  (1+XDR_QUADLEN(SM_MAXSTRLEN))
 510#define SM_mon_id_sz    (SM_mon_name_sz+SM_my_id_sz)
 511#define SM_priv_sz      (XDR_QUADLEN(SM_PRIV_SIZE))
 512#define SM_mon_sz       (SM_mon_id_sz+SM_priv_sz)
 513#define SM_monres_sz    2
 514#define SM_unmonres_sz  1
 515
 516static struct rpc_procinfo      nsm_procedures[] = {
 517[NSMPROC_MON] = {
 518                .p_proc         = NSMPROC_MON,
 519                .p_encode       = (kxdreproc_t)nsm_xdr_enc_mon,
 520                .p_decode       = (kxdrdproc_t)nsm_xdr_dec_stat_res,
 521                .p_arglen       = SM_mon_sz,
 522                .p_replen       = SM_monres_sz,
 523                .p_statidx      = NSMPROC_MON,
 524                .p_name         = "MONITOR",
 525        },
 526[NSMPROC_UNMON] = {
 527                .p_proc         = NSMPROC_UNMON,
 528                .p_encode       = (kxdreproc_t)nsm_xdr_enc_unmon,
 529                .p_decode       = (kxdrdproc_t)nsm_xdr_dec_stat,
 530                .p_arglen       = SM_mon_id_sz,
 531                .p_replen       = SM_unmonres_sz,
 532                .p_statidx      = NSMPROC_UNMON,
 533                .p_name         = "UNMONITOR",
 534        },
 535};
 536
 537static struct rpc_version       nsm_version1 = {
 538                .number         = 1,
 539                .nrprocs        = ARRAY_SIZE(nsm_procedures),
 540                .procs          = nsm_procedures
 541};
 542
 543static struct rpc_version *     nsm_version[] = {
 544        [1] = &nsm_version1,
 545};
 546
 547static struct rpc_stat          nsm_stats;
 548
 549static struct rpc_program       nsm_program = {
 550                .name           = "statd",
 551                .number         = NSM_PROGRAM,
 552                .nrvers         = ARRAY_SIZE(nsm_version),
 553                .version        = nsm_version,
 554                .stats          = &nsm_stats
 555};
 556
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