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TOMOYO Linux Cross Reference
Linux/fs/lockd/host.c

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  1 /*
  2  * linux/fs/lockd/host.c
  3  *
  4  * Management for NLM peer hosts. The nlm_host struct is shared
  5  * between client and server implementation. The only reason to
  6  * do so is to reduce code bloat.
  7  *
  8  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
  9  */
 10 
 11 #include <linux/types.h>
 12 #include <linux/slab.h>
 13 #include <linux/in.h>
 14 #include <linux/in6.h>
 15 #include <linux/sunrpc/clnt.h>
 16 #include <linux/sunrpc/addr.h>
 17 #include <linux/sunrpc/svc.h>
 18 #include <linux/lockd/lockd.h>
 19 #include <linux/mutex.h>
 20 
 21 #include <linux/sunrpc/svc_xprt.h>
 22 
 23 #include <net/ipv6.h>
 24 
 25 #include "netns.h"
 26 
 27 #define NLMDBG_FACILITY         NLMDBG_HOSTCACHE
 28 #define NLM_HOST_NRHASH         32
 29 #define NLM_HOST_REBIND         (60 * HZ)
 30 #define NLM_HOST_EXPIRE         (300 * HZ)
 31 #define NLM_HOST_COLLECT        (120 * HZ)
 32 
 33 static struct hlist_head        nlm_server_hosts[NLM_HOST_NRHASH];
 34 static struct hlist_head        nlm_client_hosts[NLM_HOST_NRHASH];
 35 
 36 #define for_each_host(host, chain, table) \
 37         for ((chain) = (table); \
 38              (chain) < (table) + NLM_HOST_NRHASH; ++(chain)) \
 39                 hlist_for_each_entry((host), (chain), h_hash)
 40 
 41 #define for_each_host_safe(host, next, chain, table) \
 42         for ((chain) = (table); \
 43              (chain) < (table) + NLM_HOST_NRHASH; ++(chain)) \
 44                 hlist_for_each_entry_safe((host), (next), \
 45                                                 (chain), h_hash)
 46 
 47 static unsigned long            nrhosts;
 48 static DEFINE_MUTEX(nlm_host_mutex);
 49 
 50 static void                     nlm_gc_hosts(struct net *net);
 51 
 52 struct nlm_lookup_host_info {
 53         const int               server;         /* search for server|client */
 54         const struct sockaddr   *sap;           /* address to search for */
 55         const size_t            salen;          /* it's length */
 56         const unsigned short    protocol;       /* transport to search for*/
 57         const u32               version;        /* NLM version to search for */
 58         const char              *hostname;      /* remote's hostname */
 59         const size_t            hostname_len;   /* it's length */
 60         const int               noresvport;     /* use non-priv port */
 61         struct net              *net;           /* network namespace to bind */
 62 };
 63 
 64 /*
 65  * Hash function must work well on big- and little-endian platforms
 66  */
 67 static unsigned int __nlm_hash32(const __be32 n)
 68 {
 69         unsigned int hash = (__force u32)n ^ ((__force u32)n >> 16);
 70         return hash ^ (hash >> 8);
 71 }
 72 
 73 static unsigned int __nlm_hash_addr4(const struct sockaddr *sap)
 74 {
 75         const struct sockaddr_in *sin = (struct sockaddr_in *)sap;
 76         return __nlm_hash32(sin->sin_addr.s_addr);
 77 }
 78 
 79 static unsigned int __nlm_hash_addr6(const struct sockaddr *sap)
 80 {
 81         const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
 82         const struct in6_addr addr = sin6->sin6_addr;
 83         return __nlm_hash32(addr.s6_addr32[0]) ^
 84                __nlm_hash32(addr.s6_addr32[1]) ^
 85                __nlm_hash32(addr.s6_addr32[2]) ^
 86                __nlm_hash32(addr.s6_addr32[3]);
 87 }
 88 
 89 static unsigned int nlm_hash_address(const struct sockaddr *sap)
 90 {
 91         unsigned int hash;
 92 
 93         switch (sap->sa_family) {
 94         case AF_INET:
 95                 hash = __nlm_hash_addr4(sap);
 96                 break;
 97         case AF_INET6:
 98                 hash = __nlm_hash_addr6(sap);
 99                 break;
100         default:
101                 hash = 0;
102         }
103         return hash & (NLM_HOST_NRHASH - 1);
104 }
105 
106 /*
107  * Allocate and initialize an nlm_host.  Common to both client and server.
108  */
109 static struct nlm_host *nlm_alloc_host(struct nlm_lookup_host_info *ni,
110                                        struct nsm_handle *nsm)
111 {
112         struct nlm_host *host = NULL;
113         unsigned long now = jiffies;
114 
115         if (nsm != NULL)
116                 atomic_inc(&nsm->sm_count);
117         else {
118                 host = NULL;
119                 nsm = nsm_get_handle(ni->net, ni->sap, ni->salen,
120                                         ni->hostname, ni->hostname_len);
121                 if (unlikely(nsm == NULL)) {
122                         dprintk("lockd: %s failed; no nsm handle\n",
123                                 __func__);
124                         goto out;
125                 }
126         }
127 
128         host = kmalloc(sizeof(*host), GFP_KERNEL);
129         if (unlikely(host == NULL)) {
130                 dprintk("lockd: %s failed; no memory\n", __func__);
131                 nsm_release(nsm);
132                 goto out;
133         }
134 
135         memcpy(nlm_addr(host), ni->sap, ni->salen);
136         host->h_addrlen    = ni->salen;
137         rpc_set_port(nlm_addr(host), 0);
138         host->h_srcaddrlen = 0;
139 
140         host->h_rpcclnt    = NULL;
141         host->h_name       = nsm->sm_name;
142         host->h_version    = ni->version;
143         host->h_proto      = ni->protocol;
144         host->h_reclaiming = 0;
145         host->h_server     = ni->server;
146         host->h_noresvport = ni->noresvport;
147         host->h_inuse      = 0;
148         init_waitqueue_head(&host->h_gracewait);
149         init_rwsem(&host->h_rwsem);
150         host->h_state      = 0;
151         host->h_nsmstate   = 0;
152         host->h_pidcount   = 0;
153         atomic_set(&host->h_count, 1);
154         mutex_init(&host->h_mutex);
155         host->h_nextrebind = now + NLM_HOST_REBIND;
156         host->h_expires    = now + NLM_HOST_EXPIRE;
157         INIT_LIST_HEAD(&host->h_lockowners);
158         spin_lock_init(&host->h_lock);
159         INIT_LIST_HEAD(&host->h_granted);
160         INIT_LIST_HEAD(&host->h_reclaim);
161         host->h_nsmhandle  = nsm;
162         host->h_addrbuf    = nsm->sm_addrbuf;
163         host->net          = ni->net;
164 
165 out:
166         return host;
167 }
168 
169 /*
170  * Destroy an nlm_host and free associated resources
171  *
172  * Caller must hold nlm_host_mutex.
173  */
174 static void nlm_destroy_host_locked(struct nlm_host *host)
175 {
176         struct rpc_clnt *clnt;
177         struct lockd_net *ln = net_generic(host->net, lockd_net_id);
178 
179         dprintk("lockd: destroy host %s\n", host->h_name);
180 
181         hlist_del_init(&host->h_hash);
182 
183         nsm_unmonitor(host);
184         nsm_release(host->h_nsmhandle);
185 
186         clnt = host->h_rpcclnt;
187         if (clnt != NULL)
188                 rpc_shutdown_client(clnt);
189         kfree(host);
190 
191         ln->nrhosts--;
192         nrhosts--;
193 }
194 
195 /**
196  * nlmclnt_lookup_host - Find an NLM host handle matching a remote server
197  * @sap: network address of server
198  * @salen: length of server address
199  * @protocol: transport protocol to use
200  * @version: NLM protocol version
201  * @hostname: '\0'-terminated hostname of server
202  * @noresvport: 1 if non-privileged port should be used
203  *
204  * Returns an nlm_host structure that matches the passed-in
205  * [server address, transport protocol, NLM version, server hostname].
206  * If one doesn't already exist in the host cache, a new handle is
207  * created and returned.
208  */
209 struct nlm_host *nlmclnt_lookup_host(const struct sockaddr *sap,
210                                      const size_t salen,
211                                      const unsigned short protocol,
212                                      const u32 version,
213                                      const char *hostname,
214                                      int noresvport,
215                                      struct net *net)
216 {
217         struct nlm_lookup_host_info ni = {
218                 .server         = 0,
219                 .sap            = sap,
220                 .salen          = salen,
221                 .protocol       = protocol,
222                 .version        = version,
223                 .hostname       = hostname,
224                 .hostname_len   = strlen(hostname),
225                 .noresvport     = noresvport,
226                 .net            = net,
227         };
228         struct hlist_head *chain;
229         struct nlm_host *host;
230         struct nsm_handle *nsm = NULL;
231         struct lockd_net *ln = net_generic(net, lockd_net_id);
232 
233         dprintk("lockd: %s(host='%s', vers=%u, proto=%s)\n", __func__,
234                         (hostname ? hostname : "<none>"), version,
235                         (protocol == IPPROTO_UDP ? "udp" : "tcp"));
236 
237         mutex_lock(&nlm_host_mutex);
238 
239         chain = &nlm_client_hosts[nlm_hash_address(sap)];
240         hlist_for_each_entry(host, chain, h_hash) {
241                 if (host->net != net)
242                         continue;
243                 if (!rpc_cmp_addr(nlm_addr(host), sap))
244                         continue;
245 
246                 /* Same address. Share an NSM handle if we already have one */
247                 if (nsm == NULL)
248                         nsm = host->h_nsmhandle;
249 
250                 if (host->h_proto != protocol)
251                         continue;
252                 if (host->h_version != version)
253                         continue;
254 
255                 nlm_get_host(host);
256                 dprintk("lockd: %s found host %s (%s)\n", __func__,
257                         host->h_name, host->h_addrbuf);
258                 goto out;
259         }
260 
261         host = nlm_alloc_host(&ni, nsm);
262         if (unlikely(host == NULL))
263                 goto out;
264 
265         hlist_add_head(&host->h_hash, chain);
266         ln->nrhosts++;
267         nrhosts++;
268 
269         dprintk("lockd: %s created host %s (%s)\n", __func__,
270                 host->h_name, host->h_addrbuf);
271 
272 out:
273         mutex_unlock(&nlm_host_mutex);
274         return host;
275 }
276 
277 /**
278  * nlmclnt_release_host - release client nlm_host
279  * @host: nlm_host to release
280  *
281  */
282 void nlmclnt_release_host(struct nlm_host *host)
283 {
284         if (host == NULL)
285                 return;
286 
287         dprintk("lockd: release client host %s\n", host->h_name);
288 
289         WARN_ON_ONCE(host->h_server);
290 
291         if (atomic_dec_and_test(&host->h_count)) {
292                 WARN_ON_ONCE(!list_empty(&host->h_lockowners));
293                 WARN_ON_ONCE(!list_empty(&host->h_granted));
294                 WARN_ON_ONCE(!list_empty(&host->h_reclaim));
295 
296                 mutex_lock(&nlm_host_mutex);
297                 nlm_destroy_host_locked(host);
298                 mutex_unlock(&nlm_host_mutex);
299         }
300 }
301 
302 /**
303  * nlmsvc_lookup_host - Find an NLM host handle matching a remote client
304  * @rqstp: incoming NLM request
305  * @hostname: name of client host
306  * @hostname_len: length of client hostname
307  *
308  * Returns an nlm_host structure that matches the [client address,
309  * transport protocol, NLM version, client hostname] of the passed-in
310  * NLM request.  If one doesn't already exist in the host cache, a
311  * new handle is created and returned.
312  *
313  * Before possibly creating a new nlm_host, construct a sockaddr
314  * for a specific source address in case the local system has
315  * multiple network addresses.  The family of the address in
316  * rq_daddr is guaranteed to be the same as the family of the
317  * address in rq_addr, so it's safe to use the same family for
318  * the source address.
319  */
320 struct nlm_host *nlmsvc_lookup_host(const struct svc_rqst *rqstp,
321                                     const char *hostname,
322                                     const size_t hostname_len)
323 {
324         struct hlist_head *chain;
325         struct nlm_host *host = NULL;
326         struct nsm_handle *nsm = NULL;
327         struct sockaddr *src_sap = svc_daddr(rqstp);
328         size_t src_len = rqstp->rq_daddrlen;
329         struct net *net = SVC_NET(rqstp);
330         struct nlm_lookup_host_info ni = {
331                 .server         = 1,
332                 .sap            = svc_addr(rqstp),
333                 .salen          = rqstp->rq_addrlen,
334                 .protocol       = rqstp->rq_prot,
335                 .version        = rqstp->rq_vers,
336                 .hostname       = hostname,
337                 .hostname_len   = hostname_len,
338                 .net            = net,
339         };
340         struct lockd_net *ln = net_generic(net, lockd_net_id);
341 
342         dprintk("lockd: %s(host='%*s', vers=%u, proto=%s)\n", __func__,
343                         (int)hostname_len, hostname, rqstp->rq_vers,
344                         (rqstp->rq_prot == IPPROTO_UDP ? "udp" : "tcp"));
345 
346         mutex_lock(&nlm_host_mutex);
347 
348         if (time_after_eq(jiffies, ln->next_gc))
349                 nlm_gc_hosts(net);
350 
351         chain = &nlm_server_hosts[nlm_hash_address(ni.sap)];
352         hlist_for_each_entry(host, chain, h_hash) {
353                 if (host->net != net)
354                         continue;
355                 if (!rpc_cmp_addr(nlm_addr(host), ni.sap))
356                         continue;
357 
358                 /* Same address. Share an NSM handle if we already have one */
359                 if (nsm == NULL)
360                         nsm = host->h_nsmhandle;
361 
362                 if (host->h_proto != ni.protocol)
363                         continue;
364                 if (host->h_version != ni.version)
365                         continue;
366                 if (!rpc_cmp_addr(nlm_srcaddr(host), src_sap))
367                         continue;
368 
369                 /* Move to head of hash chain. */
370                 hlist_del(&host->h_hash);
371                 hlist_add_head(&host->h_hash, chain);
372 
373                 nlm_get_host(host);
374                 dprintk("lockd: %s found host %s (%s)\n",
375                         __func__, host->h_name, host->h_addrbuf);
376                 goto out;
377         }
378 
379         host = nlm_alloc_host(&ni, nsm);
380         if (unlikely(host == NULL))
381                 goto out;
382 
383         memcpy(nlm_srcaddr(host), src_sap, src_len);
384         host->h_srcaddrlen = src_len;
385         hlist_add_head(&host->h_hash, chain);
386         ln->nrhosts++;
387         nrhosts++;
388 
389         dprintk("lockd: %s created host %s (%s)\n",
390                 __func__, host->h_name, host->h_addrbuf);
391 
392 out:
393         mutex_unlock(&nlm_host_mutex);
394         return host;
395 }
396 
397 /**
398  * nlmsvc_release_host - release server nlm_host
399  * @host: nlm_host to release
400  *
401  * Host is destroyed later in nlm_gc_host().
402  */
403 void nlmsvc_release_host(struct nlm_host *host)
404 {
405         if (host == NULL)
406                 return;
407 
408         dprintk("lockd: release server host %s\n", host->h_name);
409 
410         WARN_ON_ONCE(!host->h_server);
411         atomic_dec(&host->h_count);
412 }
413 
414 /*
415  * Create the NLM RPC client for an NLM peer
416  */
417 struct rpc_clnt *
418 nlm_bind_host(struct nlm_host *host)
419 {
420         struct rpc_clnt *clnt;
421 
422         dprintk("lockd: nlm_bind_host %s (%s)\n",
423                         host->h_name, host->h_addrbuf);
424 
425         /* Lock host handle */
426         mutex_lock(&host->h_mutex);
427 
428         /* If we've already created an RPC client, check whether
429          * RPC rebind is required
430          */
431         if ((clnt = host->h_rpcclnt) != NULL) {
432                 if (time_after_eq(jiffies, host->h_nextrebind)) {
433                         rpc_force_rebind(clnt);
434                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
435                         dprintk("lockd: next rebind in %lu jiffies\n",
436                                         host->h_nextrebind - jiffies);
437                 }
438         } else {
439                 unsigned long increment = nlmsvc_timeout;
440                 struct rpc_timeout timeparms = {
441                         .to_initval     = increment,
442                         .to_increment   = increment,
443                         .to_maxval      = increment * 6UL,
444                         .to_retries     = 5U,
445                 };
446                 struct rpc_create_args args = {
447                         .net            = host->net,
448                         .protocol       = host->h_proto,
449                         .address        = nlm_addr(host),
450                         .addrsize       = host->h_addrlen,
451                         .timeout        = &timeparms,
452                         .servername     = host->h_name,
453                         .program        = &nlm_program,
454                         .version        = host->h_version,
455                         .authflavor     = RPC_AUTH_UNIX,
456                         .flags          = (RPC_CLNT_CREATE_NOPING |
457                                            RPC_CLNT_CREATE_AUTOBIND),
458                 };
459 
460                 /*
461                  * lockd retries server side blocks automatically so we want
462                  * those to be soft RPC calls. Client side calls need to be
463                  * hard RPC tasks.
464                  */
465                 if (!host->h_server)
466                         args.flags |= RPC_CLNT_CREATE_HARDRTRY;
467                 if (host->h_noresvport)
468                         args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;
469                 if (host->h_srcaddrlen)
470                         args.saddress = nlm_srcaddr(host);
471 
472                 clnt = rpc_create(&args);
473                 if (!IS_ERR(clnt))
474                         host->h_rpcclnt = clnt;
475                 else {
476                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
477                         clnt = NULL;
478                 }
479         }
480 
481         mutex_unlock(&host->h_mutex);
482         return clnt;
483 }
484 
485 /*
486  * Force a portmap lookup of the remote lockd port
487  */
488 void
489 nlm_rebind_host(struct nlm_host *host)
490 {
491         dprintk("lockd: rebind host %s\n", host->h_name);
492         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
493                 rpc_force_rebind(host->h_rpcclnt);
494                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
495         }
496 }
497 
498 /*
499  * Increment NLM host count
500  */
501 struct nlm_host * nlm_get_host(struct nlm_host *host)
502 {
503         if (host) {
504                 dprintk("lockd: get host %s\n", host->h_name);
505                 atomic_inc(&host->h_count);
506                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
507         }
508         return host;
509 }
510 
511 static struct nlm_host *next_host_state(struct hlist_head *cache,
512                                         struct nsm_handle *nsm,
513                                         const struct nlm_reboot *info)
514 {
515         struct nlm_host *host;
516         struct hlist_head *chain;
517 
518         mutex_lock(&nlm_host_mutex);
519         for_each_host(host, chain, cache) {
520                 if (host->h_nsmhandle == nsm
521                     && host->h_nsmstate != info->state) {
522                         host->h_nsmstate = info->state;
523                         host->h_state++;
524 
525                         nlm_get_host(host);
526                         mutex_unlock(&nlm_host_mutex);
527                         return host;
528                 }
529         }
530 
531         mutex_unlock(&nlm_host_mutex);
532         return NULL;
533 }
534 
535 /**
536  * nlm_host_rebooted - Release all resources held by rebooted host
537  * @net:  network namespace
538  * @info: pointer to decoded results of NLM_SM_NOTIFY call
539  *
540  * We were notified that the specified host has rebooted.  Release
541  * all resources held by that peer.
542  */
543 void nlm_host_rebooted(const struct net *net, const struct nlm_reboot *info)
544 {
545         struct nsm_handle *nsm;
546         struct nlm_host *host;
547 
548         nsm = nsm_reboot_lookup(net, info);
549         if (unlikely(nsm == NULL))
550                 return;
551 
552         /* Mark all hosts tied to this NSM state as having rebooted.
553          * We run the loop repeatedly, because we drop the host table
554          * lock for this.
555          * To avoid processing a host several times, we match the nsmstate.
556          */
557         while ((host = next_host_state(nlm_server_hosts, nsm, info)) != NULL) {
558                 nlmsvc_free_host_resources(host);
559                 nlmsvc_release_host(host);
560         }
561         while ((host = next_host_state(nlm_client_hosts, nsm, info)) != NULL) {
562                 nlmclnt_recovery(host);
563                 nlmclnt_release_host(host);
564         }
565 
566         nsm_release(nsm);
567 }
568 
569 static void nlm_complain_hosts(struct net *net)
570 {
571         struct hlist_head *chain;
572         struct nlm_host *host;
573 
574         if (net) {
575                 struct lockd_net *ln = net_generic(net, lockd_net_id);
576 
577                 if (ln->nrhosts == 0)
578                         return;
579                 printk(KERN_WARNING "lockd: couldn't shutdown host module for net %p!\n", net);
580                 dprintk("lockd: %lu hosts left in net %p:\n", ln->nrhosts, net);
581         } else {
582                 if (nrhosts == 0)
583                         return;
584                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
585                 dprintk("lockd: %lu hosts left:\n", nrhosts);
586         }
587 
588         for_each_host(host, chain, nlm_server_hosts) {
589                 if (net && host->net != net)
590                         continue;
591                 dprintk("       %s (cnt %d use %d exp %ld net %p)\n",
592                         host->h_name, atomic_read(&host->h_count),
593                         host->h_inuse, host->h_expires, host->net);
594         }
595 }
596 
597 void
598 nlm_shutdown_hosts_net(struct net *net)
599 {
600         struct hlist_head *chain;
601         struct nlm_host *host;
602 
603         mutex_lock(&nlm_host_mutex);
604 
605         /* First, make all hosts eligible for gc */
606         dprintk("lockd: nuking all hosts in net %p...\n", net);
607         for_each_host(host, chain, nlm_server_hosts) {
608                 if (net && host->net != net)
609                         continue;
610                 host->h_expires = jiffies - 1;
611                 if (host->h_rpcclnt) {
612                         rpc_shutdown_client(host->h_rpcclnt);
613                         host->h_rpcclnt = NULL;
614                 }
615         }
616 
617         /* Then, perform a garbage collection pass */
618         nlm_gc_hosts(net);
619         mutex_unlock(&nlm_host_mutex);
620 
621         nlm_complain_hosts(net);
622 }
623 
624 /*
625  * Shut down the hosts module.
626  * Note that this routine is called only at server shutdown time.
627  */
628 void
629 nlm_shutdown_hosts(void)
630 {
631         dprintk("lockd: shutting down host module\n");
632         nlm_shutdown_hosts_net(NULL);
633 }
634 
635 /*
636  * Garbage collect any unused NLM hosts.
637  * This GC combines reference counting for async operations with
638  * mark & sweep for resources held by remote clients.
639  */
640 static void
641 nlm_gc_hosts(struct net *net)
642 {
643         struct hlist_head *chain;
644         struct hlist_node *next;
645         struct nlm_host *host;
646 
647         dprintk("lockd: host garbage collection for net %p\n", net);
648         for_each_host(host, chain, nlm_server_hosts) {
649                 if (net && host->net != net)
650                         continue;
651                 host->h_inuse = 0;
652         }
653 
654         /* Mark all hosts that hold locks, blocks or shares */
655         nlmsvc_mark_resources(net);
656 
657         for_each_host_safe(host, next, chain, nlm_server_hosts) {
658                 if (net && host->net != net)
659                         continue;
660                 if (atomic_read(&host->h_count) || host->h_inuse
661                  || time_before(jiffies, host->h_expires)) {
662                         dprintk("nlm_gc_hosts skipping %s "
663                                 "(cnt %d use %d exp %ld net %p)\n",
664                                 host->h_name, atomic_read(&host->h_count),
665                                 host->h_inuse, host->h_expires, host->net);
666                         continue;
667                 }
668                 nlm_destroy_host_locked(host);
669         }
670 
671         if (net) {
672                 struct lockd_net *ln = net_generic(net, lockd_net_id);
673 
674                 ln->next_gc = jiffies + NLM_HOST_COLLECT;
675         }
676 }
677 

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