Root/fs/lockd/host.c

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/svc.h>
17#include <linux/lockd/lockd.h>
18#include <linux/mutex.h>
19
20#include <net/ipv6.h>
21
22#define NLMDBG_FACILITY NLMDBG_HOSTCACHE
23#define NLM_HOST_NRHASH 32
24#define NLM_HOST_REBIND (60 * HZ)
25#define NLM_HOST_EXPIRE (300 * HZ)
26#define NLM_HOST_COLLECT (120 * HZ)
27
28static struct hlist_head nlm_server_hosts[NLM_HOST_NRHASH];
29static struct hlist_head nlm_client_hosts[NLM_HOST_NRHASH];
30
31#define for_each_host(host, pos, chain, table) \
32    for ((chain) = (table); \
33         (chain) < (table) + NLM_HOST_NRHASH; ++(chain)) \
34        hlist_for_each_entry((host), (pos), (chain), h_hash)
35
36#define for_each_host_safe(host, pos, next, chain, table) \
37    for ((chain) = (table); \
38         (chain) < (table) + NLM_HOST_NRHASH; ++(chain)) \
39        hlist_for_each_entry_safe((host), (pos), (next), \
40                        (chain), h_hash)
41
42static unsigned long next_gc;
43static unsigned long nrhosts;
44static DEFINE_MUTEX(nlm_host_mutex);
45
46static void nlm_gc_hosts(void);
47
48struct nlm_lookup_host_info {
49    const int server; /* search for server|client */
50    const struct sockaddr *sap; /* address to search for */
51    const size_t salen; /* it's length */
52    const unsigned short protocol; /* transport to search for*/
53    const u32 version; /* NLM version to search for */
54    const char *hostname; /* remote's hostname */
55    const size_t hostname_len; /* it's length */
56    const int noresvport; /* use non-priv port */
57};
58
59/*
60 * Hash function must work well on big- and little-endian platforms
61 */
62static unsigned int __nlm_hash32(const __be32 n)
63{
64    unsigned int hash = (__force u32)n ^ ((__force u32)n >> 16);
65    return hash ^ (hash >> 8);
66}
67
68static unsigned int __nlm_hash_addr4(const struct sockaddr *sap)
69{
70    const struct sockaddr_in *sin = (struct sockaddr_in *)sap;
71    return __nlm_hash32(sin->sin_addr.s_addr);
72}
73
74static unsigned int __nlm_hash_addr6(const struct sockaddr *sap)
75{
76    const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
77    const struct in6_addr addr = sin6->sin6_addr;
78    return __nlm_hash32(addr.s6_addr32[0]) ^
79           __nlm_hash32(addr.s6_addr32[1]) ^
80           __nlm_hash32(addr.s6_addr32[2]) ^
81           __nlm_hash32(addr.s6_addr32[3]);
82}
83
84static unsigned int nlm_hash_address(const struct sockaddr *sap)
85{
86    unsigned int hash;
87
88    switch (sap->sa_family) {
89    case AF_INET:
90        hash = __nlm_hash_addr4(sap);
91        break;
92    case AF_INET6:
93        hash = __nlm_hash_addr6(sap);
94        break;
95    default:
96        hash = 0;
97    }
98    return hash & (NLM_HOST_NRHASH - 1);
99}
100
101/*
102 * Allocate and initialize an nlm_host. Common to both client and server.
103 */
104static struct nlm_host *nlm_alloc_host(struct nlm_lookup_host_info *ni,
105                       struct nsm_handle *nsm)
106{
107    struct nlm_host *host = NULL;
108    unsigned long now = jiffies;
109
110    if (nsm != NULL)
111        atomic_inc(&nsm->sm_count);
112    else {
113        host = NULL;
114        nsm = nsm_get_handle(ni->sap, ni->salen,
115                    ni->hostname, ni->hostname_len);
116        if (unlikely(nsm == NULL)) {
117            dprintk("lockd: %s failed; no nsm handle\n",
118                __func__);
119            goto out;
120        }
121    }
122
123    host = kmalloc(sizeof(*host), GFP_KERNEL);
124    if (unlikely(host == NULL)) {
125        dprintk("lockd: %s failed; no memory\n", __func__);
126        nsm_release(nsm);
127        goto out;
128    }
129
130    memcpy(nlm_addr(host), ni->sap, ni->salen);
131    host->h_addrlen = ni->salen;
132    rpc_set_port(nlm_addr(host), 0);
133    host->h_srcaddrlen = 0;
134
135    host->h_rpcclnt = NULL;
136    host->h_name = nsm->sm_name;
137    host->h_version = ni->version;
138    host->h_proto = ni->protocol;
139    host->h_reclaiming = 0;
140    host->h_server = ni->server;
141    host->h_noresvport = ni->noresvport;
142    host->h_inuse = 0;
143    init_waitqueue_head(&host->h_gracewait);
144    init_rwsem(&host->h_rwsem);
145    host->h_state = 0;
146    host->h_nsmstate = 0;
147    host->h_pidcount = 0;
148    atomic_set(&host->h_count, 1);
149    mutex_init(&host->h_mutex);
150    host->h_nextrebind = now + NLM_HOST_REBIND;
151    host->h_expires = now + NLM_HOST_EXPIRE;
152    INIT_LIST_HEAD(&host->h_lockowners);
153    spin_lock_init(&host->h_lock);
154    INIT_LIST_HEAD(&host->h_granted);
155    INIT_LIST_HEAD(&host->h_reclaim);
156    host->h_nsmhandle = nsm;
157    host->h_addrbuf = nsm->sm_addrbuf;
158
159out:
160    return host;
161}
162
163/*
164 * Destroy an nlm_host and free associated resources
165 *
166 * Caller must hold nlm_host_mutex.
167 */
168static void nlm_destroy_host_locked(struct nlm_host *host)
169{
170    struct rpc_clnt *clnt;
171
172    dprintk("lockd: destroy host %s\n", host->h_name);
173
174    BUG_ON(!list_empty(&host->h_lockowners));
175    BUG_ON(atomic_read(&host->h_count));
176
177    hlist_del_init(&host->h_hash);
178
179    nsm_unmonitor(host);
180    nsm_release(host->h_nsmhandle);
181
182    clnt = host->h_rpcclnt;
183    if (clnt != NULL)
184        rpc_shutdown_client(clnt);
185    kfree(host);
186
187    nrhosts--;
188}
189
190/**
191 * nlmclnt_lookup_host - Find an NLM host handle matching a remote server
192 * @sap: network address of server
193 * @salen: length of server address
194 * @protocol: transport protocol to use
195 * @version: NLM protocol version
196 * @hostname: '\0'-terminated hostname of server
197 * @noresvport: 1 if non-privileged port should be used
198 *
199 * Returns an nlm_host structure that matches the passed-in
200 * [server address, transport protocol, NLM version, server hostname].
201 * If one doesn't already exist in the host cache, a new handle is
202 * created and returned.
203 */
204struct nlm_host *nlmclnt_lookup_host(const struct sockaddr *sap,
205                     const size_t salen,
206                     const unsigned short protocol,
207                     const u32 version,
208                     const char *hostname,
209                     int noresvport)
210{
211    struct nlm_lookup_host_info ni = {
212        .server = 0,
213        .sap = sap,
214        .salen = salen,
215        .protocol = protocol,
216        .version = version,
217        .hostname = hostname,
218        .hostname_len = strlen(hostname),
219        .noresvport = noresvport,
220    };
221    struct hlist_head *chain;
222    struct hlist_node *pos;
223    struct nlm_host *host;
224    struct nsm_handle *nsm = NULL;
225
226    dprintk("lockd: %s(host='%s', vers=%u, proto=%s)\n", __func__,
227            (hostname ? hostname : "<none>"), version,
228            (protocol == IPPROTO_UDP ? "udp" : "tcp"));
229
230    mutex_lock(&nlm_host_mutex);
231
232    chain = &nlm_client_hosts[nlm_hash_address(sap)];
233    hlist_for_each_entry(host, pos, chain, h_hash) {
234        if (!rpc_cmp_addr(nlm_addr(host), sap))
235            continue;
236
237        /* Same address. Share an NSM handle if we already have one */
238        if (nsm == NULL)
239            nsm = host->h_nsmhandle;
240
241        if (host->h_proto != protocol)
242            continue;
243        if (host->h_version != version)
244            continue;
245
246        nlm_get_host(host);
247        dprintk("lockd: %s found host %s (%s)\n", __func__,
248            host->h_name, host->h_addrbuf);
249        goto out;
250    }
251
252    host = nlm_alloc_host(&ni, nsm);
253    if (unlikely(host == NULL))
254        goto out;
255
256    hlist_add_head(&host->h_hash, chain);
257    nrhosts++;
258
259    dprintk("lockd: %s created host %s (%s)\n", __func__,
260        host->h_name, host->h_addrbuf);
261
262out:
263    mutex_unlock(&nlm_host_mutex);
264    return host;
265}
266
267/**
268 * nlmclnt_release_host - release client nlm_host
269 * @host: nlm_host to release
270 *
271 */
272void nlmclnt_release_host(struct nlm_host *host)
273{
274    if (host == NULL)
275        return;
276
277    dprintk("lockd: release client host %s\n", host->h_name);
278
279    BUG_ON(atomic_read(&host->h_count) < 0);
280    BUG_ON(host->h_server);
281
282    if (atomic_dec_and_test(&host->h_count)) {
283        BUG_ON(!list_empty(&host->h_lockowners));
284        BUG_ON(!list_empty(&host->h_granted));
285        BUG_ON(!list_empty(&host->h_reclaim));
286
287        mutex_lock(&nlm_host_mutex);
288        nlm_destroy_host_locked(host);
289        mutex_unlock(&nlm_host_mutex);
290    }
291}
292
293/**
294 * nlmsvc_lookup_host - Find an NLM host handle matching a remote client
295 * @rqstp: incoming NLM request
296 * @hostname: name of client host
297 * @hostname_len: length of client hostname
298 *
299 * Returns an nlm_host structure that matches the [client address,
300 * transport protocol, NLM version, client hostname] of the passed-in
301 * NLM request. If one doesn't already exist in the host cache, a
302 * new handle is created and returned.
303 *
304 * Before possibly creating a new nlm_host, construct a sockaddr
305 * for a specific source address in case the local system has
306 * multiple network addresses. The family of the address in
307 * rq_daddr is guaranteed to be the same as the family of the
308 * address in rq_addr, so it's safe to use the same family for
309 * the source address.
310 */
311struct nlm_host *nlmsvc_lookup_host(const struct svc_rqst *rqstp,
312                    const char *hostname,
313                    const size_t hostname_len)
314{
315    struct hlist_head *chain;
316    struct hlist_node *pos;
317    struct nlm_host *host = NULL;
318    struct nsm_handle *nsm = NULL;
319    struct sockaddr_in sin = {
320        .sin_family = AF_INET,
321    };
322    struct sockaddr_in6 sin6 = {
323        .sin6_family = AF_INET6,
324    };
325    struct sockaddr *src_sap;
326    size_t src_len = rqstp->rq_addrlen;
327    struct nlm_lookup_host_info ni = {
328        .server = 1,
329        .sap = svc_addr(rqstp),
330        .salen = rqstp->rq_addrlen,
331        .protocol = rqstp->rq_prot,
332        .version = rqstp->rq_vers,
333        .hostname = hostname,
334        .hostname_len = hostname_len,
335    };
336
337    dprintk("lockd: %s(host='%*s', vers=%u, proto=%s)\n", __func__,
338            (int)hostname_len, hostname, rqstp->rq_vers,
339            (rqstp->rq_prot == IPPROTO_UDP ? "udp" : "tcp"));
340
341    mutex_lock(&nlm_host_mutex);
342
343    switch (ni.sap->sa_family) {
344    case AF_INET:
345        sin.sin_addr.s_addr = rqstp->rq_daddr.addr.s_addr;
346        src_sap = (struct sockaddr *)&sin;
347        break;
348    case AF_INET6:
349        ipv6_addr_copy(&sin6.sin6_addr, &rqstp->rq_daddr.addr6);
350        src_sap = (struct sockaddr *)&sin6;
351        break;
352    default:
353        dprintk("lockd: %s failed; unrecognized address family\n",
354            __func__);
355        goto out;
356    }
357
358    if (time_after_eq(jiffies, next_gc))
359        nlm_gc_hosts();
360
361    chain = &nlm_server_hosts[nlm_hash_address(ni.sap)];
362    hlist_for_each_entry(host, pos, chain, h_hash) {
363        if (!rpc_cmp_addr(nlm_addr(host), ni.sap))
364            continue;
365
366        /* Same address. Share an NSM handle if we already have one */
367        if (nsm == NULL)
368            nsm = host->h_nsmhandle;
369
370        if (host->h_proto != ni.protocol)
371            continue;
372        if (host->h_version != ni.version)
373            continue;
374        if (!rpc_cmp_addr(nlm_srcaddr(host), src_sap))
375            continue;
376
377        /* Move to head of hash chain. */
378        hlist_del(&host->h_hash);
379        hlist_add_head(&host->h_hash, chain);
380
381        nlm_get_host(host);
382        dprintk("lockd: %s found host %s (%s)\n",
383            __func__, host->h_name, host->h_addrbuf);
384        goto out;
385    }
386
387    host = nlm_alloc_host(&ni, nsm);
388    if (unlikely(host == NULL))
389        goto out;
390
391    memcpy(nlm_srcaddr(host), src_sap, src_len);
392    host->h_srcaddrlen = src_len;
393    hlist_add_head(&host->h_hash, chain);
394    nrhosts++;
395
396    dprintk("lockd: %s created host %s (%s)\n",
397        __func__, host->h_name, host->h_addrbuf);
398
399out:
400    mutex_unlock(&nlm_host_mutex);
401    return host;
402}
403
404/**
405 * nlmsvc_release_host - release server nlm_host
406 * @host: nlm_host to release
407 *
408 * Host is destroyed later in nlm_gc_host().
409 */
410void nlmsvc_release_host(struct nlm_host *host)
411{
412    if (host == NULL)
413        return;
414
415    dprintk("lockd: release server host %s\n", host->h_name);
416
417    BUG_ON(atomic_read(&host->h_count) < 0);
418    BUG_ON(!host->h_server);
419    atomic_dec(&host->h_count);
420}
421
422/*
423 * Create the NLM RPC client for an NLM peer
424 */
425struct rpc_clnt *
426nlm_bind_host(struct nlm_host *host)
427{
428    struct rpc_clnt *clnt;
429
430    dprintk("lockd: nlm_bind_host %s (%s)\n",
431            host->h_name, host->h_addrbuf);
432
433    /* Lock host handle */
434    mutex_lock(&host->h_mutex);
435
436    /* If we've already created an RPC client, check whether
437     * RPC rebind is required
438     */
439    if ((clnt = host->h_rpcclnt) != NULL) {
440        if (time_after_eq(jiffies, host->h_nextrebind)) {
441            rpc_force_rebind(clnt);
442            host->h_nextrebind = jiffies + NLM_HOST_REBIND;
443            dprintk("lockd: next rebind in %lu jiffies\n",
444                    host->h_nextrebind - jiffies);
445        }
446    } else {
447        unsigned long increment = nlmsvc_timeout;
448        struct rpc_timeout timeparms = {
449            .to_initval = increment,
450            .to_increment = increment,
451            .to_maxval = increment * 6UL,
452            .to_retries = 5U,
453        };
454        struct rpc_create_args args = {
455            .net = &init_net,
456            .protocol = host->h_proto,
457            .address = nlm_addr(host),
458            .addrsize = host->h_addrlen,
459            .timeout = &timeparms,
460            .servername = host->h_name,
461            .program = &nlm_program,
462            .version = host->h_version,
463            .authflavor = RPC_AUTH_UNIX,
464            .flags = (RPC_CLNT_CREATE_NOPING |
465                       RPC_CLNT_CREATE_AUTOBIND),
466        };
467
468        /*
469         * lockd retries server side blocks automatically so we want
470         * those to be soft RPC calls. Client side calls need to be
471         * hard RPC tasks.
472         */
473        if (!host->h_server)
474            args.flags |= RPC_CLNT_CREATE_HARDRTRY;
475        if (host->h_noresvport)
476            args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;
477        if (host->h_srcaddrlen)
478            args.saddress = nlm_srcaddr(host);
479
480        clnt = rpc_create(&args);
481        if (!IS_ERR(clnt))
482            host->h_rpcclnt = clnt;
483        else {
484            printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
485            clnt = NULL;
486        }
487    }
488
489    mutex_unlock(&host->h_mutex);
490    return clnt;
491}
492
493/*
494 * Force a portmap lookup of the remote lockd port
495 */
496void
497nlm_rebind_host(struct nlm_host *host)
498{
499    dprintk("lockd: rebind host %s\n", host->h_name);
500    if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
501        rpc_force_rebind(host->h_rpcclnt);
502        host->h_nextrebind = jiffies + NLM_HOST_REBIND;
503    }
504}
505
506/*
507 * Increment NLM host count
508 */
509struct nlm_host * nlm_get_host(struct nlm_host *host)
510{
511    if (host) {
512        dprintk("lockd: get host %s\n", host->h_name);
513        atomic_inc(&host->h_count);
514        host->h_expires = jiffies + NLM_HOST_EXPIRE;
515    }
516    return host;
517}
518
519static struct nlm_host *next_host_state(struct hlist_head *cache,
520                    struct nsm_handle *nsm,
521                    const struct nlm_reboot *info)
522{
523    struct nlm_host *host;
524    struct hlist_head *chain;
525    struct hlist_node *pos;
526
527    mutex_lock(&nlm_host_mutex);
528    for_each_host(host, pos, chain, cache) {
529        if (host->h_nsmhandle == nsm
530            && host->h_nsmstate != info->state) {
531            host->h_nsmstate = info->state;
532            host->h_state++;
533
534            nlm_get_host(host);
535            mutex_unlock(&nlm_host_mutex);
536            return host;
537        }
538    }
539
540    mutex_unlock(&nlm_host_mutex);
541    return NULL;
542}
543
544/**
545 * nlm_host_rebooted - Release all resources held by rebooted host
546 * @info: pointer to decoded results of NLM_SM_NOTIFY call
547 *
548 * We were notified that the specified host has rebooted. Release
549 * all resources held by that peer.
550 */
551void nlm_host_rebooted(const struct nlm_reboot *info)
552{
553    struct nsm_handle *nsm;
554    struct nlm_host *host;
555
556    nsm = nsm_reboot_lookup(info);
557    if (unlikely(nsm == NULL))
558        return;
559
560    /* Mark all hosts tied to this NSM state as having rebooted.
561     * We run the loop repeatedly, because we drop the host table
562     * lock for this.
563     * To avoid processing a host several times, we match the nsmstate.
564     */
565    while ((host = next_host_state(nlm_server_hosts, nsm, info)) != NULL) {
566        nlmsvc_free_host_resources(host);
567        nlmsvc_release_host(host);
568    }
569    while ((host = next_host_state(nlm_client_hosts, nsm, info)) != NULL) {
570        nlmclnt_recovery(host);
571        nlmclnt_release_host(host);
572    }
573
574    nsm_release(nsm);
575}
576
577/*
578 * Shut down the hosts module.
579 * Note that this routine is called only at server shutdown time.
580 */
581void
582nlm_shutdown_hosts(void)
583{
584    struct hlist_head *chain;
585    struct hlist_node *pos;
586    struct nlm_host *host;
587
588    dprintk("lockd: shutting down host module\n");
589    mutex_lock(&nlm_host_mutex);
590
591    /* First, make all hosts eligible for gc */
592    dprintk("lockd: nuking all hosts...\n");
593    for_each_host(host, pos, chain, nlm_server_hosts) {
594        host->h_expires = jiffies - 1;
595        if (host->h_rpcclnt) {
596            rpc_shutdown_client(host->h_rpcclnt);
597            host->h_rpcclnt = NULL;
598        }
599    }
600
601    /* Then, perform a garbage collection pass */
602    nlm_gc_hosts();
603    mutex_unlock(&nlm_host_mutex);
604
605    /* complain if any hosts are left */
606    if (nrhosts != 0) {
607        printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
608        dprintk("lockd: %lu hosts left:\n", nrhosts);
609        for_each_host(host, pos, chain, nlm_server_hosts) {
610            dprintk(" %s (cnt %d use %d exp %ld)\n",
611                host->h_name, atomic_read(&host->h_count),
612                host->h_inuse, host->h_expires);
613        }
614    }
615}
616
617/*
618 * Garbage collect any unused NLM hosts.
619 * This GC combines reference counting for async operations with
620 * mark & sweep for resources held by remote clients.
621 */
622static void
623nlm_gc_hosts(void)
624{
625    struct hlist_head *chain;
626    struct hlist_node *pos, *next;
627    struct nlm_host *host;
628
629    dprintk("lockd: host garbage collection\n");
630    for_each_host(host, pos, chain, nlm_server_hosts)
631        host->h_inuse = 0;
632
633    /* Mark all hosts that hold locks, blocks or shares */
634    nlmsvc_mark_resources();
635
636    for_each_host_safe(host, pos, next, chain, nlm_server_hosts) {
637        if (atomic_read(&host->h_count) || host->h_inuse
638         || time_before(jiffies, host->h_expires)) {
639            dprintk("nlm_gc_hosts skipping %s "
640                "(cnt %d use %d exp %ld)\n",
641                host->h_name, atomic_read(&host->h_count),
642                host->h_inuse, host->h_expires);
643            continue;
644        }
645        nlm_destroy_host_locked(host);
646    }
647
648    next_gc = jiffies + NLM_HOST_COLLECT;
649}
650

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