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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 
 28 enum {
 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 
 38 struct 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         const char              *nodename;
 46 };
 47 
 48 struct nsm_res {
 49         u32                     status;
 50         u32                     state;
 51 };
 52 
 53 static const struct rpc_program nsm_program;
 54 static                          DEFINE_SPINLOCK(nsm_lock);
 55 
 56 /*
 57  * Local NSM state
 58  */
 59 u32     __read_mostly           nsm_local_state;
 60 bool    __read_mostly           nsm_use_hostnames;
 61 
 62 static inline struct sockaddr *nsm_addr(const struct nsm_handle *nsm)
 63 {
 64         return (struct sockaddr *)&nsm->sm_addr;
 65 }
 66 
 67 static struct rpc_clnt *nsm_create(struct net *net, const char *nodename)
 68 {
 69         struct sockaddr_in sin = {
 70                 .sin_family             = AF_INET,
 71                 .sin_addr.s_addr        = htonl(INADDR_LOOPBACK),
 72         };
 73         struct rpc_create_args args = {
 74                 .net                    = net,
 75                 .protocol               = XPRT_TRANSPORT_TCP,
 76                 .address                = (struct sockaddr *)&sin,
 77                 .addrsize               = sizeof(sin),
 78                 .servername             = "rpc.statd",
 79                 .nodename               = nodename,
 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 
 89 static int nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res,
 90                          const struct nlm_host *host)
 91 {
 92         int             status;
 93         struct rpc_clnt *clnt;
 94         struct nsm_args args = {
 95                 .priv           = &nsm->sm_priv,
 96                 .prog           = NLM_PROGRAM,
 97                 .vers           = 3,
 98                 .proc           = NLMPROC_NSM_NOTIFY,
 99                 .mon_name       = nsm->sm_mon_name,
100                 .nodename       = host->nodename,
101         };
102         struct rpc_message msg = {
103                 .rpc_argp       = &args,
104                 .rpc_resp       = res,
105         };
106 
107         memset(res, 0, sizeof(*res));
108 
109         clnt = nsm_create(host->net, host->nodename);
110         if (IS_ERR(clnt)) {
111                 dprintk("lockd: failed to create NSM upcall transport, "
112                         "status=%ld, net=%p\n", PTR_ERR(clnt), host->net);
113                 return PTR_ERR(clnt);
114         }
115 
116         msg.rpc_proc = &clnt->cl_procinfo[proc];
117         status = rpc_call_sync(clnt, &msg, RPC_TASK_SOFTCONN);
118         if (status == -ECONNREFUSED) {
119                 dprintk("lockd: NSM upcall RPC failed, status=%d, forcing rebind\n",
120                                 status);
121                 rpc_force_rebind(clnt);
122                 status = rpc_call_sync(clnt, &msg, RPC_TASK_SOFTCONN);
123         }
124         if (status < 0)
125                 dprintk("lockd: NSM upcall RPC failed, status=%d\n",
126                                 status);
127         else
128                 status = 0;
129 
130         rpc_shutdown_client(clnt);
131         return status;
132 }
133 
134 /**
135  * nsm_monitor - Notify a peer in case we reboot
136  * @host: pointer to nlm_host of peer to notify
137  *
138  * If this peer is not already monitored, this function sends an
139  * upcall to the local rpc.statd to record the name/address of
140  * the peer to notify in case we reboot.
141  *
142  * Returns zero if the peer is monitored by the local rpc.statd;
143  * otherwise a negative errno value is returned.
144  */
145 int nsm_monitor(const struct nlm_host *host)
146 {
147         struct nsm_handle *nsm = host->h_nsmhandle;
148         struct nsm_res  res;
149         int             status;
150 
151         dprintk("lockd: nsm_monitor(%s)\n", nsm->sm_name);
152 
153         if (nsm->sm_monitored)
154                 return 0;
155 
156         /*
157          * Choose whether to record the caller_name or IP address of
158          * this peer in the local rpc.statd's database.
159          */
160         nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf;
161 
162         status = nsm_mon_unmon(nsm, NSMPROC_MON, &res, host);
163         if (unlikely(res.status != 0))
164                 status = -EIO;
165         if (unlikely(status < 0)) {
166                 pr_notice_ratelimited("lockd: cannot monitor %s\n", nsm->sm_name);
167                 return status;
168         }
169 
170         nsm->sm_monitored = 1;
171         if (unlikely(nsm_local_state != res.state)) {
172                 nsm_local_state = res.state;
173                 dprintk("lockd: NSM state changed to %d\n", nsm_local_state);
174         }
175         return 0;
176 }
177 
178 /**
179  * nsm_unmonitor - Unregister peer notification
180  * @host: pointer to nlm_host of peer to stop monitoring
181  *
182  * If this peer is monitored, this function sends an upcall to
183  * tell the local rpc.statd not to send this peer a notification
184  * when we reboot.
185  */
186 void nsm_unmonitor(const struct nlm_host *host)
187 {
188         struct nsm_handle *nsm = host->h_nsmhandle;
189         struct nsm_res  res;
190         int status;
191 
192         if (atomic_read(&nsm->sm_count) == 1
193          && nsm->sm_monitored && !nsm->sm_sticky) {
194                 dprintk("lockd: nsm_unmonitor(%s)\n", nsm->sm_name);
195 
196                 status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res, host);
197                 if (res.status != 0)
198                         status = -EIO;
199                 if (status < 0)
200                         printk(KERN_NOTICE "lockd: cannot unmonitor %s\n",
201                                         nsm->sm_name);
202                 else
203                         nsm->sm_monitored = 0;
204         }
205 }
206 
207 static struct nsm_handle *nsm_lookup_hostname(const struct list_head *nsm_handles,
208                                         const char *hostname, const size_t len)
209 {
210         struct nsm_handle *nsm;
211 
212         list_for_each_entry(nsm, nsm_handles, sm_link)
213                 if (strlen(nsm->sm_name) == len &&
214                     memcmp(nsm->sm_name, hostname, len) == 0)
215                         return nsm;
216         return NULL;
217 }
218 
219 static struct nsm_handle *nsm_lookup_addr(const struct list_head *nsm_handles,
220                                         const struct sockaddr *sap)
221 {
222         struct nsm_handle *nsm;
223 
224         list_for_each_entry(nsm, nsm_handles, sm_link)
225                 if (rpc_cmp_addr(nsm_addr(nsm), sap))
226                         return nsm;
227         return NULL;
228 }
229 
230 static struct nsm_handle *nsm_lookup_priv(const struct list_head *nsm_handles,
231                                         const struct nsm_private *priv)
232 {
233         struct nsm_handle *nsm;
234 
235         list_for_each_entry(nsm, nsm_handles, sm_link)
236                 if (memcmp(nsm->sm_priv.data, priv->data,
237                                         sizeof(priv->data)) == 0)
238                         return nsm;
239         return NULL;
240 }
241 
242 /*
243  * Construct a unique cookie to match this nsm_handle to this monitored
244  * host.  It is passed to the local rpc.statd via NSMPROC_MON, and
245  * returned via NLMPROC_SM_NOTIFY, in the "priv" field of these
246  * requests.
247  *
248  * The NSM protocol requires that these cookies be unique while the
249  * system is running.  We prefer a stronger requirement of making them
250  * unique across reboots.  If user space bugs cause a stale cookie to
251  * be sent to the kernel, it could cause the wrong host to lose its
252  * lock state if cookies were not unique across reboots.
253  *
254  * The cookies are exposed only to local user space via loopback.  They
255  * do not appear on the physical network.  If we want greater security
256  * for some reason, nsm_init_private() could perform a one-way hash to
257  * obscure the contents of the cookie.
258  */
259 static void nsm_init_private(struct nsm_handle *nsm)
260 {
261         u64 *p = (u64 *)&nsm->sm_priv.data;
262         s64 ns;
263 
264         ns = ktime_get_ns();
265         put_unaligned(ns, p);
266         put_unaligned((unsigned long)nsm, p + 1);
267 }
268 
269 static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
270                                             const size_t salen,
271                                             const char *hostname,
272                                             const size_t hostname_len)
273 {
274         struct nsm_handle *new;
275 
276         new = kzalloc(sizeof(*new) + hostname_len + 1, GFP_KERNEL);
277         if (unlikely(new == NULL))
278                 return NULL;
279 
280         atomic_set(&new->sm_count, 1);
281         new->sm_name = (char *)(new + 1);
282         memcpy(nsm_addr(new), sap, salen);
283         new->sm_addrlen = salen;
284         nsm_init_private(new);
285 
286         if (rpc_ntop(nsm_addr(new), new->sm_addrbuf,
287                                         sizeof(new->sm_addrbuf)) == 0)
288                 (void)snprintf(new->sm_addrbuf, sizeof(new->sm_addrbuf),
289                                 "unsupported address family");
290         memcpy(new->sm_name, hostname, hostname_len);
291         new->sm_name[hostname_len] = '\0';
292 
293         return new;
294 }
295 
296 /**
297  * nsm_get_handle - Find or create a cached nsm_handle
298  * @net: network namespace
299  * @sap: pointer to socket address of handle to find
300  * @salen: length of socket address
301  * @hostname: pointer to C string containing hostname to find
302  * @hostname_len: length of C string
303  *
304  * Behavior is modulated by the global nsm_use_hostnames variable.
305  *
306  * Returns a cached nsm_handle after bumping its ref count, or
307  * returns a fresh nsm_handle if a handle that matches @sap and/or
308  * @hostname cannot be found in the handle cache.  Returns NULL if
309  * an error occurs.
310  */
311 struct nsm_handle *nsm_get_handle(const struct net *net,
312                                   const struct sockaddr *sap,
313                                   const size_t salen, const char *hostname,
314                                   const size_t hostname_len)
315 {
316         struct nsm_handle *cached, *new = NULL;
317         struct lockd_net *ln = net_generic(net, lockd_net_id);
318 
319         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
320                 if (printk_ratelimit()) {
321                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
322                                             "in NFS lock request\n",
323                                 (int)hostname_len, hostname);
324                 }
325                 return NULL;
326         }
327 
328 retry:
329         spin_lock(&nsm_lock);
330 
331         if (nsm_use_hostnames && hostname != NULL)
332                 cached = nsm_lookup_hostname(&ln->nsm_handles,
333                                         hostname, hostname_len);
334         else
335                 cached = nsm_lookup_addr(&ln->nsm_handles, sap);
336 
337         if (cached != NULL) {
338                 atomic_inc(&cached->sm_count);
339                 spin_unlock(&nsm_lock);
340                 kfree(new);
341                 dprintk("lockd: found nsm_handle for %s (%s), "
342                                 "cnt %d\n", cached->sm_name,
343                                 cached->sm_addrbuf,
344                                 atomic_read(&cached->sm_count));
345                 return cached;
346         }
347 
348         if (new != NULL) {
349                 list_add(&new->sm_link, &ln->nsm_handles);
350                 spin_unlock(&nsm_lock);
351                 dprintk("lockd: created nsm_handle for %s (%s)\n",
352                                 new->sm_name, new->sm_addrbuf);
353                 return new;
354         }
355 
356         spin_unlock(&nsm_lock);
357 
358         new = nsm_create_handle(sap, salen, hostname, hostname_len);
359         if (unlikely(new == NULL))
360                 return NULL;
361         goto retry;
362 }
363 
364 /**
365  * nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
366  * @net:  network namespace
367  * @info: pointer to NLMPROC_SM_NOTIFY arguments
368  *
369  * Returns a matching nsm_handle if found in the nsm cache. The returned
370  * nsm_handle's reference count is bumped. Otherwise returns NULL if some
371  * error occurred.
372  */
373 struct nsm_handle *nsm_reboot_lookup(const struct net *net,
374                                 const struct nlm_reboot *info)
375 {
376         struct nsm_handle *cached;
377         struct lockd_net *ln = net_generic(net, lockd_net_id);
378 
379         spin_lock(&nsm_lock);
380 
381         cached = nsm_lookup_priv(&ln->nsm_handles, &info->priv);
382         if (unlikely(cached == NULL)) {
383                 spin_unlock(&nsm_lock);
384                 dprintk("lockd: never saw rebooted peer '%.*s' before\n",
385                                 info->len, info->mon);
386                 return cached;
387         }
388 
389         atomic_inc(&cached->sm_count);
390         spin_unlock(&nsm_lock);
391 
392         dprintk("lockd: host %s (%s) rebooted, cnt %d\n",
393                         cached->sm_name, cached->sm_addrbuf,
394                         atomic_read(&cached->sm_count));
395         return cached;
396 }
397 
398 /**
399  * nsm_release - Release an NSM handle
400  * @nsm: pointer to handle to be released
401  *
402  */
403 void nsm_release(struct nsm_handle *nsm)
404 {
405         if (atomic_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
406                 list_del(&nsm->sm_link);
407                 spin_unlock(&nsm_lock);
408                 dprintk("lockd: destroyed nsm_handle for %s (%s)\n",
409                                 nsm->sm_name, nsm->sm_addrbuf);
410                 kfree(nsm);
411         }
412 }
413 
414 /*
415  * XDR functions for NSM.
416  *
417  * See http://www.opengroup.org/ for details on the Network
418  * Status Monitor wire protocol.
419  */
420 
421 static void encode_nsm_string(struct xdr_stream *xdr, const char *string)
422 {
423         const u32 len = strlen(string);
424         __be32 *p;
425 
426         p = xdr_reserve_space(xdr, 4 + len);
427         xdr_encode_opaque(p, string, len);
428 }
429 
430 /*
431  * "mon_name" specifies the host to be monitored.
432  */
433 static void encode_mon_name(struct xdr_stream *xdr, const struct nsm_args *argp)
434 {
435         encode_nsm_string(xdr, argp->mon_name);
436 }
437 
438 /*
439  * The "my_id" argument specifies the hostname and RPC procedure
440  * to be called when the status manager receives notification
441  * (via the NLMPROC_SM_NOTIFY call) that the state of host "mon_name"
442  * has changed.
443  */
444 static void encode_my_id(struct xdr_stream *xdr, const struct nsm_args *argp)
445 {
446         __be32 *p;
447 
448         encode_nsm_string(xdr, argp->nodename);
449         p = xdr_reserve_space(xdr, 4 + 4 + 4);
450         *p++ = cpu_to_be32(argp->prog);
451         *p++ = cpu_to_be32(argp->vers);
452         *p = cpu_to_be32(argp->proc);
453 }
454 
455 /*
456  * The "mon_id" argument specifies the non-private arguments
457  * of an NSMPROC_MON or NSMPROC_UNMON call.
458  */
459 static void encode_mon_id(struct xdr_stream *xdr, const struct nsm_args *argp)
460 {
461         encode_mon_name(xdr, argp);
462         encode_my_id(xdr, argp);
463 }
464 
465 /*
466  * The "priv" argument may contain private information required
467  * by the NSMPROC_MON call. This information will be supplied in the
468  * NLMPROC_SM_NOTIFY call.
469  */
470 static void encode_priv(struct xdr_stream *xdr, const struct nsm_args *argp)
471 {
472         __be32 *p;
473 
474         p = xdr_reserve_space(xdr, SM_PRIV_SIZE);
475         xdr_encode_opaque_fixed(p, argp->priv->data, SM_PRIV_SIZE);
476 }
477 
478 static void nsm_xdr_enc_mon(struct rpc_rqst *req, struct xdr_stream *xdr,
479                             const void *argp)
480 {
481         encode_mon_id(xdr, argp);
482         encode_priv(xdr, argp);
483 }
484 
485 static void nsm_xdr_enc_unmon(struct rpc_rqst *req, struct xdr_stream *xdr,
486                               const void *argp)
487 {
488         encode_mon_id(xdr, argp);
489 }
490 
491 static int nsm_xdr_dec_stat_res(struct rpc_rqst *rqstp,
492                                 struct xdr_stream *xdr,
493                                 void *data)
494 {
495         struct nsm_res *resp = data;
496         __be32 *p;
497 
498         p = xdr_inline_decode(xdr, 4 + 4);
499         if (unlikely(p == NULL))
500                 return -EIO;
501         resp->status = be32_to_cpup(p++);
502         resp->state = be32_to_cpup(p);
503 
504         dprintk("lockd: %s status %d state %d\n",
505                 __func__, resp->status, resp->state);
506         return 0;
507 }
508 
509 static int nsm_xdr_dec_stat(struct rpc_rqst *rqstp,
510                             struct xdr_stream *xdr,
511                             void *data)
512 {
513         struct nsm_res *resp = data;
514         __be32 *p;
515 
516         p = xdr_inline_decode(xdr, 4);
517         if (unlikely(p == NULL))
518                 return -EIO;
519         resp->state = be32_to_cpup(p);
520 
521         dprintk("lockd: %s state %d\n", __func__, resp->state);
522         return 0;
523 }
524 
525 #define SM_my_name_sz   (1+XDR_QUADLEN(SM_MAXSTRLEN))
526 #define SM_my_id_sz     (SM_my_name_sz+3)
527 #define SM_mon_name_sz  (1+XDR_QUADLEN(SM_MAXSTRLEN))
528 #define SM_mon_id_sz    (SM_mon_name_sz+SM_my_id_sz)
529 #define SM_priv_sz      (XDR_QUADLEN(SM_PRIV_SIZE))
530 #define SM_mon_sz       (SM_mon_id_sz+SM_priv_sz)
531 #define SM_monres_sz    2
532 #define SM_unmonres_sz  1
533 
534 static const struct rpc_procinfo nsm_procedures[] = {
535 [NSMPROC_MON] = {
536                 .p_proc         = NSMPROC_MON,
537                 .p_encode       = nsm_xdr_enc_mon,
538                 .p_decode       = nsm_xdr_dec_stat_res,
539                 .p_arglen       = SM_mon_sz,
540                 .p_replen       = SM_monres_sz,
541                 .p_statidx      = NSMPROC_MON,
542                 .p_name         = "MONITOR",
543         },
544 [NSMPROC_UNMON] = {
545                 .p_proc         = NSMPROC_UNMON,
546                 .p_encode       = nsm_xdr_enc_unmon,
547                 .p_decode       = nsm_xdr_dec_stat,
548                 .p_arglen       = SM_mon_id_sz,
549                 .p_replen       = SM_unmonres_sz,
550                 .p_statidx      = NSMPROC_UNMON,
551                 .p_name         = "UNMONITOR",
552         },
553 };
554 
555 static unsigned int nsm_version1_counts[ARRAY_SIZE(nsm_procedures)];
556 static const struct rpc_version nsm_version1 = {
557         .number         = 1,
558         .nrprocs        = ARRAY_SIZE(nsm_procedures),
559         .procs          = nsm_procedures,
560         .counts         = nsm_version1_counts,
561 };
562 
563 static const struct rpc_version *nsm_version[] = {
564         [1] = &nsm_version1,
565 };
566 
567 static struct rpc_stat          nsm_stats;
568 
569 static const struct rpc_program nsm_program = {
570         .name           = "statd",
571         .number         = NSM_PROGRAM,
572         .nrvers         = ARRAY_SIZE(nsm_version),
573         .version        = nsm_version,
574         .stats          = &nsm_stats
575 };
576 

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