Root/fs/lockd/mon.c

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