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