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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/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 
 26 enum {
 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 
 36 struct 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 
 45 struct nsm_res {
 46         u32                     status;
 47         u32                     state;
 48 };
 49 
 50 static struct rpc_program       nsm_program;
 51 static                          LIST_HEAD(nsm_handles);
 52 static                          DEFINE_SPINLOCK(nsm_lock);
 53 
 54 /*
 55  * Local NSM state
 56  */
 57 u32     __read_mostly           nsm_local_state;
 58 int     __read_mostly           nsm_use_hostnames;
 59 
 60 static inline struct sockaddr *nsm_addr(const struct nsm_handle *nsm)
 61 {
 62         return (struct sockaddr *)&nsm->sm_addr;
 63 }
 64 
 65 static 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 
 86 static 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  */
135 int 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  */
176 void 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 
197 static 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 
209 static 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 
219 static 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  */
247 static 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 
259 static 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  */
300 struct 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 
315 retry:
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  */
358 struct 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  */
386 void 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 
404 static 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  */
417 static 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  */
428 static 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  */
443 static 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  */
454 static 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 
462 static 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 
469 static 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 
475 static 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 
492 static 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 
516 static 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 
537 static struct rpc_version       nsm_version1 = {
538                 .number         = 1,
539                 .nrprocs        = ARRAY_SIZE(nsm_procedures),
540                 .procs          = nsm_procedures
541 };
542 
543 static struct rpc_version *     nsm_version[] = {
544         [1] = &nsm_version1,
545 };
546 
547 static struct rpc_stat          nsm_stats;
548 
549 static 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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