fs/lockd/mon.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/fs/lockd/mon.c
   4  *
   5  * The kernel statd client.
   6  *
   7  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   8  */
   9
  10 #include <linux/types.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/addr.h>
  17 #include <linux/sunrpc/xprtsock.h>
  18 #include <linux/sunrpc/svc.h>
  19 #include <linux/lockd/lockd.h>
  20
  21 #include <asm/unaligned.h>
  22
  23 #include "netns.h"
  24
  25 #define NLMDBG_FACILITY         NLMDBG_MONITOR
  26 #define NSM_PROGRAM             100024
  27 #define NSM_VERSION             1
  28
  29 enum {
  30         NSMPROC_NULL,
  31         NSMPROC_STAT,
  32         NSMPROC_MON,
  33         NSMPROC_UNMON,
  34         NSMPROC_UNMON_ALL,
  35         NSMPROC_SIMU_CRASH,
  36         NSMPROC_NOTIFY,
  37 };
  38
  39 struct nsm_args {
  40         struct nsm_private      *priv;
  41         u32                     prog;           /* RPC callback info */
  42         u32                     vers;
  43         u32                     proc;
  44
  45         char                    *mon_name;
  46         const char              *nodename;
  47 };
  48
  49 struct nsm_res {
  50         u32                     status;
  51         u32                     state;
  52 };
  53
  54 static const struct rpc_program nsm_program;
  55 static                          DEFINE_SPINLOCK(nsm_lock);
  56
  57 /*
  58  * Local NSM state
  59  */
  60 u32     __read_mostly           nsm_local_state;
  61 bool    __read_mostly           nsm_use_hostnames;
  62
  63 static inline struct sockaddr *nsm_addr(const struct nsm_handle *nsm)
  64 {
  65         return (struct sockaddr *)&nsm->sm_addr;
  66 }
  67
  68 static struct rpc_clnt *nsm_create(struct net *net, const char *nodename)
  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                 .nodename               = nodename,
  81                 .program                = &nsm_program,
  82                 .version                = NSM_VERSION,
  83                 .authflavor             = RPC_AUTH_NULL,
  84                 .flags                  = RPC_CLNT_CREATE_NOPING,
  85                 .cred                   = current_cred(),
  86         };
  87
  88         return rpc_create(&args);
  89 }
  90
  91 static int nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res,
  92                          const struct nlm_host *host)
  93 {
  94         int             status;
  95         struct rpc_clnt *clnt;
  96         struct nsm_args args = {
  97                 .priv           = &nsm->sm_priv,
  98                 .prog           = NLM_PROGRAM,
  99                 .vers           = 3,
 100                 .proc           = NLMPROC_NSM_NOTIFY,
 101                 .mon_name       = nsm->sm_mon_name,
 102                 .nodename       = host->nodename,
 103         };
 104         struct rpc_message msg = {
 105                 .rpc_argp       = &args,
 106                 .rpc_resp       = res,
 107         };
 108
 109         memset(res, 0, sizeof(*res));
 110
 111         clnt = nsm_create(host->net, host->nodename);
 112         if (IS_ERR(clnt)) {
 113                 dprintk("lockd: failed to create NSM upcall transport, "
 114                         "status=%ld, net=%x\n", PTR_ERR(clnt),
 115                         host->net->ns.inum);
 116                 return PTR_ERR(clnt);
 117         }
 118
 119         msg.rpc_proc = &clnt->cl_procinfo[proc];
 120         status = rpc_call_sync(clnt, &msg, RPC_TASK_SOFTCONN);
 121         if (status == -ECONNREFUSED) {
 122                 dprintk("lockd: NSM upcall RPC failed, status=%d, forcing rebind\n",
 123                                 status);
 124                 rpc_force_rebind(clnt);
 125                 status = rpc_call_sync(clnt, &msg, RPC_TASK_SOFTCONN);
 126         }
 127         if (status < 0)
 128                 dprintk("lockd: NSM upcall RPC failed, status=%d\n",
 129                                 status);
 130         else
 131                 status = 0;
 132
 133         rpc_shutdown_client(clnt);
 134         return status;
 135 }
 136
 137 /**
 138  * nsm_monitor - Notify a peer in case we reboot
 139  * @host: pointer to nlm_host of peer to notify
 140  *
 141  * If this peer is not already monitored, this function sends an
 142  * upcall to the local rpc.statd to record the name/address of
 143  * the peer to notify in case we reboot.
 144  *
 145  * Returns zero if the peer is monitored by the local rpc.statd;
 146  * otherwise a negative errno value is returned.
 147  */
 148 int nsm_monitor(const struct nlm_host *host)
 149 {
 150         struct nsm_handle *nsm = host->h_nsmhandle;
 151         struct nsm_res  res;
 152         int             status;
 153
 154         dprintk("lockd: nsm_monitor(%s)\n", nsm->sm_name);
 155
 156         if (nsm->sm_monitored)
 157                 return 0;
 158
 159         /*
 160          * Choose whether to record the caller_name or IP address of
 161          * this peer in the local rpc.statd's database.
 162          */
 163         nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf;
 164
 165         status = nsm_mon_unmon(nsm, NSMPROC_MON, &res, host);
 166         if (unlikely(res.status != 0))
 167                 status = -EIO;
 168         if (unlikely(status < 0)) {
 169                 pr_notice_ratelimited("lockd: cannot monitor %s\n", nsm->sm_name);
 170                 return status;
 171         }
 172
 173         nsm->sm_monitored = 1;
 174         if (unlikely(nsm_local_state != res.state)) {
 175                 nsm_local_state = res.state;
 176                 dprintk("lockd: NSM state changed to %d\n", nsm_local_state);
 177         }
 178         return 0;
 179 }
 180
 181 /**
 182  * nsm_unmonitor - Unregister peer notification
 183  * @host: pointer to nlm_host of peer to stop monitoring
 184  *
 185  * If this peer is monitored, this function sends an upcall to
 186  * tell the local rpc.statd not to send this peer a notification
 187  * when we reboot.
 188  */
 189 void nsm_unmonitor(const struct nlm_host *host)
 190 {
 191         struct nsm_handle *nsm = host->h_nsmhandle;
 192         struct nsm_res  res;
 193         int status;
 194
 195         if (refcount_read(&nsm->sm_count) == 1
 196          && nsm->sm_monitored && !nsm->sm_sticky) {
 197                 dprintk("lockd: nsm_unmonitor(%s)\n", nsm->sm_name);
 198
 199                 status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res, host);
 200                 if (res.status != 0)
 201                         status = -EIO;
 202                 if (status < 0)
 203                         printk(KERN_NOTICE "lockd: cannot unmonitor %s\n",
 204                                         nsm->sm_name);
 205                 else
 206                         nsm->sm_monitored = 0;
 207         }
 208 }
 209
 210 static struct nsm_handle *nsm_lookup_hostname(const struct list_head *nsm_handles,
 211                                         const char *hostname, const size_t len)
 212 {
 213         struct nsm_handle *nsm;
 214
 215         list_for_each_entry(nsm, nsm_handles, sm_link)
 216                 if (strlen(nsm->sm_name) == len &&
 217                     memcmp(nsm->sm_name, hostname, len) == 0)
 218                         return nsm;
 219         return NULL;
 220 }
 221
 222 static struct nsm_handle *nsm_lookup_addr(const struct list_head *nsm_handles,
 223                                         const struct sockaddr *sap)
 224 {
 225         struct nsm_handle *nsm;
 226
 227         list_for_each_entry(nsm, nsm_handles, sm_link)
 228                 if (rpc_cmp_addr(nsm_addr(nsm), sap))
 229                         return nsm;
 230         return NULL;
 231 }
 232
 233 static struct nsm_handle *nsm_lookup_priv(const struct list_head *nsm_handles,
 234                                         const struct nsm_private *priv)
 235 {
 236         struct nsm_handle *nsm;
 237
 238         list_for_each_entry(nsm, nsm_handles, sm_link)
 239                 if (memcmp(nsm->sm_priv.data, priv->data,
 240                                         sizeof(priv->data)) == 0)
 241                         return nsm;
 242         return NULL;
 243 }
 244
 245 /*
 246  * Construct a unique cookie to match this nsm_handle to this monitored
 247  * host.  It is passed to the local rpc.statd via NSMPROC_MON, and
 248  * returned via NLMPROC_SM_NOTIFY, in the "priv" field of these
 249  * requests.
 250  *
 251  * The NSM protocol requires that these cookies be unique while the
 252  * system is running.  We prefer a stronger requirement of making them
 253  * unique across reboots.  If user space bugs cause a stale cookie to
 254  * be sent to the kernel, it could cause the wrong host to lose its
 255  * lock state if cookies were not unique across reboots.
 256  *
 257  * The cookies are exposed only to local user space via loopback.  They
 258  * do not appear on the physical network.  If we want greater security
 259  * for some reason, nsm_init_private() could perform a one-way hash to
 260  * obscure the contents of the cookie.
 261  */
 262 static void nsm_init_private(struct nsm_handle *nsm)
 263 {
 264         u64 *p = (u64 *)&nsm->sm_priv.data;
 265         s64 ns;
 266
 267         ns = ktime_get_ns();
 268         put_unaligned(ns, p);
 269         put_unaligned((unsigned long)nsm, p + 1);
 270 }
 271
 272 static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
 273                                             const size_t salen,
 274                                             const char *hostname,
 275                                             const size_t hostname_len)
 276 {
 277         struct nsm_handle *new;
 278
 279         new = kzalloc(sizeof(*new) + hostname_len + 1, GFP_KERNEL);
 280         if (unlikely(new == NULL))
 281                 return NULL;
 282
 283         refcount_set(&new->sm_count, 1);
 284         new->sm_name = (char *)(new + 1);
 285         memcpy(nsm_addr(new), sap, salen);
 286         new->sm_addrlen = salen;
 287         nsm_init_private(new);
 288
 289         if (rpc_ntop(nsm_addr(new), new->sm_addrbuf,
 290                                         sizeof(new->sm_addrbuf)) == 0)
 291                 (void)snprintf(new->sm_addrbuf, sizeof(new->sm_addrbuf),
 292                                 "unsupported address family");
 293         memcpy(new->sm_name, hostname, hostname_len);
 294         new->sm_name[hostname_len] = '\0';
 295
 296         return new;
 297 }
 298
 299 /**
 300  * nsm_get_handle - Find or create a cached nsm_handle
 301  * @net: network namespace
 302  * @sap: pointer to socket address of handle to find
 303  * @salen: length of socket address
 304  * @hostname: pointer to C string containing hostname to find
 305  * @hostname_len: length of C string
 306  *
 307  * Behavior is modulated by the global nsm_use_hostnames variable.
 308  *
 309  * Returns a cached nsm_handle after bumping its ref count, or
 310  * returns a fresh nsm_handle if a handle that matches @sap and/or
 311  * @hostname cannot be found in the handle cache.  Returns NULL if
 312  * an error occurs.
 313  */
 314 struct nsm_handle *nsm_get_handle(const struct net *net,
 315                                   const struct sockaddr *sap,
 316                                   const size_t salen, const char *hostname,
 317                                   const size_t hostname_len)
 318 {
 319         struct nsm_handle *cached, *new = NULL;
 320         struct lockd_net *ln = net_generic(net, lockd_net_id);
 321
 322         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
 323                 if (printk_ratelimit()) {
 324                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
 325                                             "in NFS lock request\n",
 326                                 (int)hostname_len, hostname);
 327                 }
 328                 return NULL;
 329         }
 330
 331 retry:
 332         spin_lock(&nsm_lock);
 333
 334         if (nsm_use_hostnames && hostname != NULL)
 335                 cached = nsm_lookup_hostname(&ln->nsm_handles,
 336                                         hostname, hostname_len);
 337         else
 338                 cached = nsm_lookup_addr(&ln->nsm_handles, sap);
 339
 340         if (cached != NULL) {
 341                 refcount_inc(&cached->sm_count);
 342                 spin_unlock(&nsm_lock);
 343                 kfree(new);
 344                 dprintk("lockd: found nsm_handle for %s (%s), "
 345                                 "cnt %d\n", cached->sm_name,
 346                                 cached->sm_addrbuf,
 347                                 refcount_read(&cached->sm_count));
 348                 return cached;
 349         }
 350
 351         if (new != NULL) {
 352                 list_add(&new->sm_link, &ln->nsm_handles);
 353                 spin_unlock(&nsm_lock);
 354                 dprintk("lockd: created nsm_handle for %s (%s)\n",
 355                                 new->sm_name, new->sm_addrbuf);
 356                 return new;
 357         }
 358
 359         spin_unlock(&nsm_lock);
 360
 361         new = nsm_create_handle(sap, salen, hostname, hostname_len);
 362         if (unlikely(new == NULL))
 363                 return NULL;
 364         goto retry;
 365 }
 366
 367 /**
 368  * nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
 369  * @net:  network namespace
 370  * @info: pointer to NLMPROC_SM_NOTIFY arguments
 371  *
 372  * Returns a matching nsm_handle if found in the nsm cache. The returned
 373  * nsm_handle's reference count is bumped. Otherwise returns NULL if some
 374  * error occurred.
 375  */
 376 struct nsm_handle *nsm_reboot_lookup(const struct net *net,
 377                                 const struct nlm_reboot *info)
 378 {
 379         struct nsm_handle *cached;
 380         struct lockd_net *ln = net_generic(net, lockd_net_id);
 381
 382         spin_lock(&nsm_lock);
 383
 384         cached = nsm_lookup_priv(&ln->nsm_handles, &info->priv);
 385         if (unlikely(cached == NULL)) {
 386                 spin_unlock(&nsm_lock);
 387                 dprintk("lockd: never saw rebooted peer '%.*s' before\n",
 388                                 info->len, info->mon);
 389                 return cached;
 390         }
 391
 392         refcount_inc(&cached->sm_count);
 393         spin_unlock(&nsm_lock);
 394
 395         dprintk("lockd: host %s (%s) rebooted, cnt %d\n",
 396                         cached->sm_name, cached->sm_addrbuf,
 397                         refcount_read(&cached->sm_count));
 398         return cached;
 399 }
 400
 401 /**
 402  * nsm_release - Release an NSM handle
 403  * @nsm: pointer to handle to be released
 404  *
 405  */
 406 void nsm_release(struct nsm_handle *nsm)
 407 {
 408         if (refcount_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
 409                 list_del(&nsm->sm_link);
 410                 spin_unlock(&nsm_lock);
 411                 dprintk("lockd: destroyed nsm_handle for %s (%s)\n",
 412                                 nsm->sm_name, nsm->sm_addrbuf);
 413                 kfree(nsm);
 414         }
 415 }
 416
 417 /*
 418  * XDR functions for NSM.
 419  *
 420  * See http://www.opengroup.org/ for details on the Network
 421  * Status Monitor wire protocol.
 422  */
 423
 424 static void encode_nsm_string(struct xdr_stream *xdr, const char *string)
 425 {
 426         const u32 len = strlen(string);
 427         __be32 *p;
 428
 429         p = xdr_reserve_space(xdr, 4 + len);
 430         xdr_encode_opaque(p, string, len);
 431 }
 432
 433 /*
 434  * "mon_name" specifies the host to be monitored.
 435  */
 436 static void encode_mon_name(struct xdr_stream *xdr, const struct nsm_args *argp)
 437 {
 438         encode_nsm_string(xdr, argp->mon_name);
 439 }
 440
 441 /*
 442  * The "my_id" argument specifies the hostname and RPC procedure
 443  * to be called when the status manager receives notification
 444  * (via the NLMPROC_SM_NOTIFY call) that the state of host "mon_name"
 445  * has changed.
 446  */
 447 static void encode_my_id(struct xdr_stream *xdr, const struct nsm_args *argp)
 448 {
 449         __be32 *p;
 450
 451         encode_nsm_string(xdr, argp->nodename);
 452         p = xdr_reserve_space(xdr, 4 + 4 + 4);
 453         *p++ = cpu_to_be32(argp->prog);
 454         *p++ = cpu_to_be32(argp->vers);
 455         *p = cpu_to_be32(argp->proc);
 456 }
 457
 458 /*
 459  * The "mon_id" argument specifies the non-private arguments
 460  * of an NSMPROC_MON or NSMPROC_UNMON call.
 461  */
 462 static void encode_mon_id(struct xdr_stream *xdr, const struct nsm_args *argp)
 463 {
 464         encode_mon_name(xdr, argp);
 465         encode_my_id(xdr, argp);
 466 }
 467
 468 /*
 469  * The "priv" argument may contain private information required
 470  * by the NSMPROC_MON call. This information will be supplied in the
 471  * NLMPROC_SM_NOTIFY call.
 472  */
 473 static void encode_priv(struct xdr_stream *xdr, const struct nsm_args *argp)
 474 {
 475         __be32 *p;
 476
 477         p = xdr_reserve_space(xdr, SM_PRIV_SIZE);
 478         xdr_encode_opaque_fixed(p, argp->priv->data, SM_PRIV_SIZE);
 479 }
 480
 481 static void nsm_xdr_enc_mon(struct rpc_rqst *req, struct xdr_stream *xdr,
 482                             const void *argp)
 483 {
 484         encode_mon_id(xdr, argp);
 485         encode_priv(xdr, argp);
 486 }
 487
 488 static void nsm_xdr_enc_unmon(struct rpc_rqst *req, struct xdr_stream *xdr,
 489                               const void *argp)
 490 {
 491         encode_mon_id(xdr, argp);
 492 }
 493
 494 static int nsm_xdr_dec_stat_res(struct rpc_rqst *rqstp,
 495                                 struct xdr_stream *xdr,
 496                                 void *data)
 497 {
 498         struct nsm_res *resp = data;
 499         __be32 *p;
 500
 501         p = xdr_inline_decode(xdr, 4 + 4);
 502         if (unlikely(p == NULL))
 503                 return -EIO;
 504         resp->status = be32_to_cpup(p++);
 505         resp->state = be32_to_cpup(p);
 506
 507         dprintk("lockd: %s status %d state %d\n",
 508                 __func__, resp->status, resp->state);
 509         return 0;
 510 }
 511
 512 static int nsm_xdr_dec_stat(struct rpc_rqst *rqstp,
 513                             struct xdr_stream *xdr,
 514                             void *data)
 515 {
 516         struct nsm_res *resp = data;
 517         __be32 *p;
 518
 519         p = xdr_inline_decode(xdr, 4);
 520         if (unlikely(p == NULL))
 521                 return -EIO;
 522         resp->state = be32_to_cpup(p);
 523
 524         dprintk("lockd: %s state %d\n", __func__, resp->state);
 525         return 0;
 526 }
 527
 528 #define SM_my_name_sz   (1+XDR_QUADLEN(SM_MAXSTRLEN))
 529 #define SM_my_id_sz     (SM_my_name_sz+3)
 530 #define SM_mon_name_sz  (1+XDR_QUADLEN(SM_MAXSTRLEN))
 531 #define SM_mon_id_sz    (SM_mon_name_sz+SM_my_id_sz)
 532 #define SM_priv_sz      (XDR_QUADLEN(SM_PRIV_SIZE))
 533 #define SM_mon_sz       (SM_mon_id_sz+SM_priv_sz)
 534 #define SM_monres_sz    2
 535 #define SM_unmonres_sz  1
 536
 537 static const struct rpc_procinfo nsm_procedures[] = {
 538 [NSMPROC_MON] = {
 539                 .p_proc         = NSMPROC_MON,
 540                 .p_encode       = nsm_xdr_enc_mon,
 541                 .p_decode       = nsm_xdr_dec_stat_res,
 542                 .p_arglen       = SM_mon_sz,
 543                 .p_replen       = SM_monres_sz,
 544                 .p_statidx      = NSMPROC_MON,
 545                 .p_name         = "MONITOR",
 546         },
 547 [NSMPROC_UNMON] = {
 548                 .p_proc         = NSMPROC_UNMON,
 549                 .p_encode       = nsm_xdr_enc_unmon,
 550                 .p_decode       = nsm_xdr_dec_stat,
 551                 .p_arglen       = SM_mon_id_sz,
 552                 .p_replen       = SM_unmonres_sz,
 553                 .p_statidx      = NSMPROC_UNMON,
 554                 .p_name         = "UNMONITOR",
 555         },
 556 };
 557
 558 static unsigned int nsm_version1_counts[ARRAY_SIZE(nsm_procedures)];
 559 static const struct rpc_version nsm_version1 = {
 560         .number         = 1,
 561         .nrprocs        = ARRAY_SIZE(nsm_procedures),
 562         .procs          = nsm_procedures,
 563         .counts         = nsm_version1_counts,
 564 };
 565
 566 static const struct rpc_version *nsm_version[] = {
 567         [1] = &nsm_version1,
 568 };
 569
 570 static struct rpc_stat          nsm_stats;
 571
 572 static const struct rpc_program nsm_program = {
 573         .name           = "statd",
 574         .number         = NSM_PROGRAM,
 575         .nrvers         = ARRAY_SIZE(nsm_version),
 576         .version        = nsm_version,
 577         .stats          = &nsm_stats
 578 };