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
28enum {
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
38struct 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	char			*nodename;
46};
47
48struct nsm_res {
49	u32			status;
50	u32			state;
51};
52
53static const struct rpc_program	nsm_program;
54static				LIST_HEAD(nsm_handles);
55static				DEFINE_SPINLOCK(nsm_lock);
56
57/*
58 * Local NSM state
59 */
60u32	__read_mostly		nsm_local_state;
61bool	__read_mostly		nsm_use_hostnames;
62
63static inline struct sockaddr *nsm_addr(const struct nsm_handle *nsm)
64{
65	return (struct sockaddr *)&nsm->sm_addr;
66}
67
68static struct rpc_clnt *nsm_create(struct net *net, const char *nodename)
69{
70	struct sockaddr_in sin = {
71		.sin_family		= AF_INET,
72		.sin_addr.s_addr	= htonl(INADDR_LOOPBACK),
73	};
74	struct rpc_create_args args = {
75		.net			= net,
76		.protocol		= XPRT_TRANSPORT_TCP,
77		.address		= (struct sockaddr *)&sin,
78		.addrsize		= sizeof(sin),
79		.servername		= "rpc.statd",
80		.nodename		= nodename,
81		.program		= &nsm_program,
82		.version		= NSM_VERSION,
83		.authflavor		= RPC_AUTH_NULL,
84		.flags			= RPC_CLNT_CREATE_NOPING,
85	};
86
87	return rpc_create(&args);
88}
89
90static struct rpc_clnt *nsm_client_set(struct lockd_net *ln,
91		struct rpc_clnt *clnt)
92{
93	spin_lock(&ln->nsm_clnt_lock);
94	if (ln->nsm_users == 0) {
95		if (clnt == NULL)
96			goto out;
97		ln->nsm_clnt = clnt;
98	}
99	clnt = ln->nsm_clnt;
100	ln->nsm_users++;
101out:
102	spin_unlock(&ln->nsm_clnt_lock);
103	return clnt;
104}
105
106static struct rpc_clnt *nsm_client_get(struct net *net, const char *nodename)
107{
108	struct rpc_clnt	*clnt, *new;
109	struct lockd_net *ln = net_generic(net, lockd_net_id);
110
111	clnt = nsm_client_set(ln, NULL);
112	if (clnt != NULL)
113		goto out;
114
115	clnt = new = nsm_create(net, nodename);
116	if (IS_ERR(clnt))
117		goto out;
118
119	clnt = nsm_client_set(ln, new);
120	if (clnt != new)
121		rpc_shutdown_client(new);
122out:
123	return clnt;
124}
125
126static void nsm_client_put(struct net *net)
127{
128	struct lockd_net *ln = net_generic(net, lockd_net_id);
129	struct rpc_clnt	*clnt = NULL;
130
131	spin_lock(&ln->nsm_clnt_lock);
132	ln->nsm_users--;
133	if (ln->nsm_users == 0) {
134		clnt = ln->nsm_clnt;
135		ln->nsm_clnt = NULL;
136	}
137	spin_unlock(&ln->nsm_clnt_lock);
138	if (clnt != NULL)
139		rpc_shutdown_client(clnt);
140}
141
142static int nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res,
143			 struct rpc_clnt *clnt)
144{
145	int		status;
146	struct nsm_args args = {
147		.priv		= &nsm->sm_priv,
148		.prog		= NLM_PROGRAM,
149		.vers		= 3,
150		.proc		= NLMPROC_NSM_NOTIFY,
151		.mon_name	= nsm->sm_mon_name,
152		.nodename	= clnt->cl_nodename,
153	};
154	struct rpc_message msg = {
155		.rpc_argp	= &args,
156		.rpc_resp	= res,
157	};
158
159	memset(res, 0, sizeof(*res));
160
161	msg.rpc_proc = &clnt->cl_procinfo[proc];
162	status = rpc_call_sync(clnt, &msg, RPC_TASK_SOFTCONN);
163	if (status == -ECONNREFUSED) {
164		dprintk("lockd:	NSM upcall RPC failed, status=%d, forcing rebind\n",
165				status);
166		rpc_force_rebind(clnt);
167		status = rpc_call_sync(clnt, &msg, RPC_TASK_SOFTCONN);
168	}
169	if (status < 0)
170		dprintk("lockd: NSM upcall RPC failed, status=%d\n",
171				status);
172	else
173		status = 0;
174	return status;
175}
176
177/**
178 * nsm_monitor - Notify a peer in case we reboot
179 * @host: pointer to nlm_host of peer to notify
180 *
181 * If this peer is not already monitored, this function sends an
182 * upcall to the local rpc.statd to record the name/address of
183 * the peer to notify in case we reboot.
184 *
185 * Returns zero if the peer is monitored by the local rpc.statd;
186 * otherwise a negative errno value is returned.
187 */
188int nsm_monitor(const struct nlm_host *host)
189{
190	struct nsm_handle *nsm = host->h_nsmhandle;
191	struct nsm_res	res;
192	int		status;
193	struct rpc_clnt *clnt;
194	const char *nodename = NULL;
195
196	dprintk("lockd: nsm_monitor(%s)\n", nsm->sm_name);
197
198	if (nsm->sm_monitored)
199		return 0;
200
201	if (host->h_rpcclnt)
202		nodename = host->h_rpcclnt->cl_nodename;
203
204	/*
205	 * Choose whether to record the caller_name or IP address of
206	 * this peer in the local rpc.statd's database.
207	 */
208	nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf;
209
210	clnt = nsm_client_get(host->net, nodename);
211	if (IS_ERR(clnt)) {
212		status = PTR_ERR(clnt);
213		dprintk("lockd: failed to create NSM upcall transport, "
214				"status=%d, net=%p\n", status, host->net);
215		return status;
216	}
217
218	status = nsm_mon_unmon(nsm, NSMPROC_MON, &res, clnt);
219	if (unlikely(res.status != 0))
220		status = -EIO;
221	if (unlikely(status < 0)) {
222		pr_notice_ratelimited("lockd: cannot monitor %s\n", nsm->sm_name);
223		return status;
224	}
225
226	nsm->sm_monitored = 1;
227	if (unlikely(nsm_local_state != res.state)) {
228		nsm_local_state = res.state;
229		dprintk("lockd: NSM state changed to %d\n", nsm_local_state);
230	}
231	return 0;
232}
233
234/**
235 * nsm_unmonitor - Unregister peer notification
236 * @host: pointer to nlm_host of peer to stop monitoring
237 *
238 * If this peer is monitored, this function sends an upcall to
239 * tell the local rpc.statd not to send this peer a notification
240 * when we reboot.
241 */
242void nsm_unmonitor(const struct nlm_host *host)
243{
244	struct nsm_handle *nsm = host->h_nsmhandle;
245	struct nsm_res	res;
246	int status;
247
248	if (atomic_read(&nsm->sm_count) == 1
249	 && nsm->sm_monitored && !nsm->sm_sticky) {
250		struct lockd_net *ln = net_generic(host->net, lockd_net_id);
251
252		dprintk("lockd: nsm_unmonitor(%s)\n", nsm->sm_name);
253
254		status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res, ln->nsm_clnt);
255		if (res.status != 0)
256			status = -EIO;
257		if (status < 0)
258			printk(KERN_NOTICE "lockd: cannot unmonitor %s\n",
259					nsm->sm_name);
260		else
261			nsm->sm_monitored = 0;
262
263		nsm_client_put(host->net);
264	}
265}
266
267static struct nsm_handle *nsm_lookup_hostname(const char *hostname,
268					      const size_t len)
269{
270	struct nsm_handle *nsm;
271
272	list_for_each_entry(nsm, &nsm_handles, sm_link)
273		if (strlen(nsm->sm_name) == len &&
274		    memcmp(nsm->sm_name, hostname, len) == 0)
275			return nsm;
276	return NULL;
277}
278
279static struct nsm_handle *nsm_lookup_addr(const struct sockaddr *sap)
280{
281	struct nsm_handle *nsm;
282
283	list_for_each_entry(nsm, &nsm_handles, sm_link)
284		if (rpc_cmp_addr(nsm_addr(nsm), sap))
285			return nsm;
286	return NULL;
287}
288
289static struct nsm_handle *nsm_lookup_priv(const struct nsm_private *priv)
290{
291	struct nsm_handle *nsm;
292
293	list_for_each_entry(nsm, &nsm_handles, sm_link)
294		if (memcmp(nsm->sm_priv.data, priv->data,
295					sizeof(priv->data)) == 0)
296			return nsm;
297	return NULL;
298}
299
300/*
301 * Construct a unique cookie to match this nsm_handle to this monitored
302 * host.  It is passed to the local rpc.statd via NSMPROC_MON, and
303 * returned via NLMPROC_SM_NOTIFY, in the "priv" field of these
304 * requests.
305 *
306 * The NSM protocol requires that these cookies be unique while the
307 * system is running.  We prefer a stronger requirement of making them
308 * unique across reboots.  If user space bugs cause a stale cookie to
309 * be sent to the kernel, it could cause the wrong host to lose its
310 * lock state if cookies were not unique across reboots.
311 *
312 * The cookies are exposed only to local user space via loopback.  They
313 * do not appear on the physical network.  If we want greater security
314 * for some reason, nsm_init_private() could perform a one-way hash to
315 * obscure the contents of the cookie.
316 */
317static void nsm_init_private(struct nsm_handle *nsm)
318{
319	u64 *p = (u64 *)&nsm->sm_priv.data;
320	s64 ns;
321
322	ns = ktime_get_ns();
323	put_unaligned(ns, p);
324	put_unaligned((unsigned long)nsm, p + 1);
325}
326
327static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
328					    const size_t salen,
329					    const char *hostname,
330					    const size_t hostname_len)
331{
332	struct nsm_handle *new;
333
334	new = kzalloc(sizeof(*new) + hostname_len + 1, GFP_KERNEL);
335	if (unlikely(new == NULL))
336		return NULL;
337
338	atomic_set(&new->sm_count, 1);
339	new->sm_name = (char *)(new + 1);
340	memcpy(nsm_addr(new), sap, salen);
341	new->sm_addrlen = salen;
342	nsm_init_private(new);
343
344	if (rpc_ntop(nsm_addr(new), new->sm_addrbuf,
345					sizeof(new->sm_addrbuf)) == 0)
346		(void)snprintf(new->sm_addrbuf, sizeof(new->sm_addrbuf),
347				"unsupported address family");
348	memcpy(new->sm_name, hostname, hostname_len);
349	new->sm_name[hostname_len] = '\0';
350
351	return new;
352}
353
354/**
355 * nsm_get_handle - Find or create a cached nsm_handle
356 * @sap: pointer to socket address of handle to find
357 * @salen: length of socket address
358 * @hostname: pointer to C string containing hostname to find
359 * @hostname_len: length of C string
360 *
361 * Behavior is modulated by the global nsm_use_hostnames variable.
362 *
363 * Returns a cached nsm_handle after bumping its ref count, or
364 * returns a fresh nsm_handle if a handle that matches @sap and/or
365 * @hostname cannot be found in the handle cache.  Returns NULL if
366 * an error occurs.
367 */
368struct nsm_handle *nsm_get_handle(const struct sockaddr *sap,
369				  const size_t salen, const char *hostname,
370				  const size_t hostname_len)
371{
372	struct nsm_handle *cached, *new = NULL;
373
374	if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
375		if (printk_ratelimit()) {
376			printk(KERN_WARNING "Invalid hostname \"%.*s\" "
377					    "in NFS lock request\n",
378				(int)hostname_len, hostname);
379		}
380		return NULL;
381	}
382
383retry:
384	spin_lock(&nsm_lock);
385
386	if (nsm_use_hostnames && hostname != NULL)
387		cached = nsm_lookup_hostname(hostname, hostname_len);
388	else
389		cached = nsm_lookup_addr(sap);
390
391	if (cached != NULL) {
392		atomic_inc(&cached->sm_count);
393		spin_unlock(&nsm_lock);
394		kfree(new);
395		dprintk("lockd: found nsm_handle for %s (%s), "
396				"cnt %d\n", cached->sm_name,
397				cached->sm_addrbuf,
398				atomic_read(&cached->sm_count));
399		return cached;
400	}
401
402	if (new != NULL) {
403		list_add(&new->sm_link, &nsm_handles);
404		spin_unlock(&nsm_lock);
405		dprintk("lockd: created nsm_handle for %s (%s)\n",
406				new->sm_name, new->sm_addrbuf);
407		return new;
408	}
409
410	spin_unlock(&nsm_lock);
411
412	new = nsm_create_handle(sap, salen, hostname, hostname_len);
413	if (unlikely(new == NULL))
414		return NULL;
415	goto retry;
416}
417
418/**
419 * nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
420 * @info: pointer to NLMPROC_SM_NOTIFY arguments
421 *
422 * Returns a matching nsm_handle if found in the nsm cache. The returned
423 * nsm_handle's reference count is bumped. Otherwise returns NULL if some
424 * error occurred.
425 */
426struct nsm_handle *nsm_reboot_lookup(const struct nlm_reboot *info)
427{
428	struct nsm_handle *cached;
429
430	spin_lock(&nsm_lock);
431
432	cached = nsm_lookup_priv(&info->priv);
433	if (unlikely(cached == NULL)) {
434		spin_unlock(&nsm_lock);
435		dprintk("lockd: never saw rebooted peer '%.*s' before\n",
436				info->len, info->mon);
437		return cached;
438	}
439
440	atomic_inc(&cached->sm_count);
441	spin_unlock(&nsm_lock);
442
443	dprintk("lockd: host %s (%s) rebooted, cnt %d\n",
444			cached->sm_name, cached->sm_addrbuf,
445			atomic_read(&cached->sm_count));
446	return cached;
447}
448
449/**
450 * nsm_release - Release an NSM handle
451 * @nsm: pointer to handle to be released
452 *
453 */
454void nsm_release(struct nsm_handle *nsm)
455{
456	if (atomic_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
457		list_del(&nsm->sm_link);
458		spin_unlock(&nsm_lock);
459		dprintk("lockd: destroyed nsm_handle for %s (%s)\n",
460				nsm->sm_name, nsm->sm_addrbuf);
461		kfree(nsm);
462	}
463}
464
465/*
466 * XDR functions for NSM.
467 *
468 * See http://www.opengroup.org/ for details on the Network
469 * Status Monitor wire protocol.
470 */
471
472static void encode_nsm_string(struct xdr_stream *xdr, const char *string)
473{
474	const u32 len = strlen(string);
475	__be32 *p;
476
477	p = xdr_reserve_space(xdr, 4 + len);
478	xdr_encode_opaque(p, string, len);
479}
480
481/*
482 * "mon_name" specifies the host to be monitored.
483 */
484static void encode_mon_name(struct xdr_stream *xdr, const struct nsm_args *argp)
485{
486	encode_nsm_string(xdr, argp->mon_name);
487}
488
489/*
490 * The "my_id" argument specifies the hostname and RPC procedure
491 * to be called when the status manager receives notification
492 * (via the NLMPROC_SM_NOTIFY call) that the state of host "mon_name"
493 * has changed.
494 */
495static void encode_my_id(struct xdr_stream *xdr, const struct nsm_args *argp)
496{
497	__be32 *p;
498
499	encode_nsm_string(xdr, argp->nodename);
500	p = xdr_reserve_space(xdr, 4 + 4 + 4);
501	*p++ = cpu_to_be32(argp->prog);
502	*p++ = cpu_to_be32(argp->vers);
503	*p = cpu_to_be32(argp->proc);
504}
505
506/*
507 * The "mon_id" argument specifies the non-private arguments
508 * of an NSMPROC_MON or NSMPROC_UNMON call.
509 */
510static void encode_mon_id(struct xdr_stream *xdr, const struct nsm_args *argp)
511{
512	encode_mon_name(xdr, argp);
513	encode_my_id(xdr, argp);
514}
515
516/*
517 * The "priv" argument may contain private information required
518 * by the NSMPROC_MON call. This information will be supplied in the
519 * NLMPROC_SM_NOTIFY call.
520 */
521static void encode_priv(struct xdr_stream *xdr, const struct nsm_args *argp)
522{
523	__be32 *p;
524
525	p = xdr_reserve_space(xdr, SM_PRIV_SIZE);
526	xdr_encode_opaque_fixed(p, argp->priv->data, SM_PRIV_SIZE);
527}
528
529static void nsm_xdr_enc_mon(struct rpc_rqst *req, struct xdr_stream *xdr,
530			    const struct nsm_args *argp)
531{
532	encode_mon_id(xdr, argp);
533	encode_priv(xdr, argp);
534}
535
536static void nsm_xdr_enc_unmon(struct rpc_rqst *req, struct xdr_stream *xdr,
537			      const struct nsm_args *argp)
538{
539	encode_mon_id(xdr, argp);
540}
541
542static int nsm_xdr_dec_stat_res(struct rpc_rqst *rqstp,
543				struct xdr_stream *xdr,
544				struct nsm_res *resp)
545{
546	__be32 *p;
547
548	p = xdr_inline_decode(xdr, 4 + 4);
549	if (unlikely(p == NULL))
550		return -EIO;
551	resp->status = be32_to_cpup(p++);
552	resp->state = be32_to_cpup(p);
553
554	dprintk("lockd: %s status %d state %d\n",
555		__func__, resp->status, resp->state);
556	return 0;
557}
558
559static int nsm_xdr_dec_stat(struct rpc_rqst *rqstp,
560			    struct xdr_stream *xdr,
561			    struct nsm_res *resp)
562{
563	__be32 *p;
564
565	p = xdr_inline_decode(xdr, 4);
566	if (unlikely(p == NULL))
567		return -EIO;
568	resp->state = be32_to_cpup(p);
569
570	dprintk("lockd: %s state %d\n", __func__, resp->state);
571	return 0;
572}
573
574#define SM_my_name_sz	(1+XDR_QUADLEN(SM_MAXSTRLEN))
575#define SM_my_id_sz	(SM_my_name_sz+3)
576#define SM_mon_name_sz	(1+XDR_QUADLEN(SM_MAXSTRLEN))
577#define SM_mon_id_sz	(SM_mon_name_sz+SM_my_id_sz)
578#define SM_priv_sz	(XDR_QUADLEN(SM_PRIV_SIZE))
579#define SM_mon_sz	(SM_mon_id_sz+SM_priv_sz)
580#define SM_monres_sz	2
581#define SM_unmonres_sz	1
582
583static struct rpc_procinfo	nsm_procedures[] = {
584[NSMPROC_MON] = {
585		.p_proc		= NSMPROC_MON,
586		.p_encode	= (kxdreproc_t)nsm_xdr_enc_mon,
587		.p_decode	= (kxdrdproc_t)nsm_xdr_dec_stat_res,
588		.p_arglen	= SM_mon_sz,
589		.p_replen	= SM_monres_sz,
590		.p_statidx	= NSMPROC_MON,
591		.p_name		= "MONITOR",
592	},
593[NSMPROC_UNMON] = {
594		.p_proc		= NSMPROC_UNMON,
595		.p_encode	= (kxdreproc_t)nsm_xdr_enc_unmon,
596		.p_decode	= (kxdrdproc_t)nsm_xdr_dec_stat,
597		.p_arglen	= SM_mon_id_sz,
598		.p_replen	= SM_unmonres_sz,
599		.p_statidx	= NSMPROC_UNMON,
600		.p_name		= "UNMONITOR",
601	},
602};
603
604static const struct rpc_version nsm_version1 = {
605		.number		= 1,
606		.nrprocs	= ARRAY_SIZE(nsm_procedures),
607		.procs		= nsm_procedures
608};
609
610static const struct rpc_version *nsm_version[] = {
611	[1] = &nsm_version1,
612};
613
614static struct rpc_stat		nsm_stats;
615
616static const struct rpc_program nsm_program = {
617		.name		= "statd",
618		.number		= NSM_PROGRAM,
619		.nrvers		= ARRAY_SIZE(nsm_version),
620		.version	= nsm_version,
621		.stats		= &nsm_stats
622};
623