1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/lockd/mon.c
4 *
5 * The kernel statd client.
6 *
7 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
8 */
9
10#include <linux/types.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/addr.h>
17#include <linux/sunrpc/xprtsock.h>
18#include <linux/sunrpc/svc.h>
19#include <linux/lockd/lockd.h>
20
21#include <asm/unaligned.h>
22
23#include "netns.h"
24
25#define NLMDBG_FACILITY		NLMDBG_MONITOR
26#define NSM_PROGRAM		100024
27#define NSM_VERSION		1
28
29enum {
30	NSMPROC_NULL,
31	NSMPROC_STAT,
32	NSMPROC_MON,
33	NSMPROC_UNMON,
34	NSMPROC_UNMON_ALL,
35	NSMPROC_SIMU_CRASH,
36	NSMPROC_NOTIFY,
37};
38
39struct nsm_args {
40	struct nsm_private	*priv;
41	u32			prog;		/* RPC callback info */
42	u32			vers;
43	u32			proc;
44
45	char			*mon_name;
46	const char		*nodename;
47};
48
49struct nsm_res {
50	u32			status;
51	u32			state;
52};
53
54static const struct rpc_program	nsm_program;
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		.cred			= current_cred(),
86	};
87
88	return rpc_create(&args);
89}
90
91static int nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res,
92			 const struct nlm_host *host)
93{
94	int		status;
95	struct rpc_clnt *clnt;
96	struct nsm_args args = {
97		.priv		= &nsm->sm_priv,
98		.prog		= NLM_PROGRAM,
99		.vers		= 3,
100		.proc		= NLMPROC_NSM_NOTIFY,
101		.mon_name	= nsm->sm_mon_name,
102		.nodename	= host->nodename,
103	};
104	struct rpc_message msg = {
105		.rpc_argp	= &args,
106		.rpc_resp	= res,
107	};
108
109	memset(res, 0, sizeof(*res));
110
111	clnt = nsm_create(host->net, host->nodename);
112	if (IS_ERR(clnt)) {
113		dprintk("lockd: failed to create NSM upcall transport, "
114			"status=%ld, net=%x\n", PTR_ERR(clnt),
115			host->net->ns.inum);
116		return PTR_ERR(clnt);
117	}
118
119	msg.rpc_proc = &clnt->cl_procinfo[proc];
120	status = rpc_call_sync(clnt, &msg, RPC_TASK_SOFTCONN);
121	if (status == -ECONNREFUSED) {
122		dprintk("lockd:	NSM upcall RPC failed, status=%d, forcing rebind\n",
123				status);
124		rpc_force_rebind(clnt);
125		status = rpc_call_sync(clnt, &msg, RPC_TASK_SOFTCONN);
126	}
127	if (status < 0)
128		dprintk("lockd: NSM upcall RPC failed, status=%d\n",
129				status);
130	else
131		status = 0;
132
133	rpc_shutdown_client(clnt);
134	return status;
135}
136
137/**
138 * nsm_monitor - Notify a peer in case we reboot
139 * @host: pointer to nlm_host of peer to notify
140 *
141 * If this peer is not already monitored, this function sends an
142 * upcall to the local rpc.statd to record the name/address of
143 * the peer to notify in case we reboot.
144 *
145 * Returns zero if the peer is monitored by the local rpc.statd;
146 * otherwise a negative errno value is returned.
147 */
148int nsm_monitor(const struct nlm_host *host)
149{
150	struct nsm_handle *nsm = host->h_nsmhandle;
151	struct nsm_res	res;
152	int		status;
153
154	dprintk("lockd: nsm_monitor(%s)\n", nsm->sm_name);
155
156	if (nsm->sm_monitored)
157		return 0;
158
159	/*
160	 * Choose whether to record the caller_name or IP address of
161	 * this peer in the local rpc.statd's database.
162	 */
163	nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf;
164
165	status = nsm_mon_unmon(nsm, NSMPROC_MON, &res, host);
166	if (unlikely(res.status != 0))
167		status = -EIO;
168	if (unlikely(status < 0)) {
169		pr_notice_ratelimited("lockd: cannot monitor %s\n", nsm->sm_name);
170		return status;
171	}
172
173	nsm->sm_monitored = 1;
174	if (unlikely(nsm_local_state != res.state)) {
175		nsm_local_state = res.state;
176		dprintk("lockd: NSM state changed to %d\n", nsm_local_state);
177	}
178	return 0;
179}
180
181/**
182 * nsm_unmonitor - Unregister peer notification
183 * @host: pointer to nlm_host of peer to stop monitoring
184 *
185 * If this peer is monitored, this function sends an upcall to
186 * tell the local rpc.statd not to send this peer a notification
187 * when we reboot.
188 */
189void nsm_unmonitor(const struct nlm_host *host)
190{
191	struct nsm_handle *nsm = host->h_nsmhandle;
192	struct nsm_res	res;
193	int status;
194
195	if (refcount_read(&nsm->sm_count) == 1
196	 && nsm->sm_monitored && !nsm->sm_sticky) {
197		dprintk("lockd: nsm_unmonitor(%s)\n", nsm->sm_name);
198
199		status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res, host);
200		if (res.status != 0)
201			status = -EIO;
202		if (status < 0)
203			printk(KERN_NOTICE "lockd: cannot unmonitor %s\n",
204					nsm->sm_name);
205		else
206			nsm->sm_monitored = 0;
207	}
208}
209
210static struct nsm_handle *nsm_lookup_hostname(const struct list_head *nsm_handles,
211					const char *hostname, const size_t len)
212{
213	struct nsm_handle *nsm;
214
215	list_for_each_entry(nsm, nsm_handles, sm_link)
216		if (strlen(nsm->sm_name) == len &&
217		    memcmp(nsm->sm_name, hostname, len) == 0)
218			return nsm;
219	return NULL;
220}
221
222static struct nsm_handle *nsm_lookup_addr(const struct list_head *nsm_handles,
223					const struct sockaddr *sap)
224{
225	struct nsm_handle *nsm;
226
227	list_for_each_entry(nsm, nsm_handles, sm_link)
228		if (rpc_cmp_addr(nsm_addr(nsm), sap))
229			return nsm;
230	return NULL;
231}
232
233static struct nsm_handle *nsm_lookup_priv(const struct list_head *nsm_handles,
234					const struct nsm_private *priv)
235{
236	struct nsm_handle *nsm;
237
238	list_for_each_entry(nsm, nsm_handles, sm_link)
239		if (memcmp(nsm->sm_priv.data, priv->data,
240					sizeof(priv->data)) == 0)
241			return nsm;
242	return NULL;
243}
244
245/*
246 * Construct a unique cookie to match this nsm_handle to this monitored
247 * host.  It is passed to the local rpc.statd via NSMPROC_MON, and
248 * returned via NLMPROC_SM_NOTIFY, in the "priv" field of these
249 * requests.
250 *
251 * The NSM protocol requires that these cookies be unique while the
252 * system is running.  We prefer a stronger requirement of making them
253 * unique across reboots.  If user space bugs cause a stale cookie to
254 * be sent to the kernel, it could cause the wrong host to lose its
255 * lock state if cookies were not unique across reboots.
256 *
257 * The cookies are exposed only to local user space via loopback.  They
258 * do not appear on the physical network.  If we want greater security
259 * for some reason, nsm_init_private() could perform a one-way hash to
260 * obscure the contents of the cookie.
261 */
262static void nsm_init_private(struct nsm_handle *nsm)
263{
264	u64 *p = (u64 *)&nsm->sm_priv.data;
265	s64 ns;
266
267	ns = ktime_get_ns();
268	put_unaligned(ns, p);
269	put_unaligned((unsigned long)nsm, p + 1);
270}
271
272static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
273					    const size_t salen,
274					    const char *hostname,
275					    const size_t hostname_len)
276{
277	struct nsm_handle *new;
278
279	if (!hostname)
280		return NULL;
281
282	new = kzalloc(sizeof(*new) + hostname_len + 1, GFP_KERNEL);
283	if (unlikely(new == NULL))
284		return NULL;
285
286	refcount_set(&new->sm_count, 1);
287	new->sm_name = (char *)(new + 1);
288	memcpy(nsm_addr(new), sap, salen);
289	new->sm_addrlen = salen;
290	nsm_init_private(new);
291
292	if (rpc_ntop(nsm_addr(new), new->sm_addrbuf,
293					sizeof(new->sm_addrbuf)) == 0)
294		(void)snprintf(new->sm_addrbuf, sizeof(new->sm_addrbuf),
295				"unsupported address family");
296	memcpy(new->sm_name, hostname, hostname_len);
297	new->sm_name[hostname_len] = '\0';
298
299	return new;
300}
301
302/**
303 * nsm_get_handle - Find or create a cached nsm_handle
304 * @net: network namespace
305 * @sap: pointer to socket address of handle to find
306 * @salen: length of socket address
307 * @hostname: pointer to C string containing hostname to find
308 * @hostname_len: length of C string
309 *
310 * Behavior is modulated by the global nsm_use_hostnames variable.
311 *
312 * Returns a cached nsm_handle after bumping its ref count, or
313 * returns a fresh nsm_handle if a handle that matches @sap and/or
314 * @hostname cannot be found in the handle cache.  Returns NULL if
315 * an error occurs.
316 */
317struct nsm_handle *nsm_get_handle(const struct net *net,
318				  const struct sockaddr *sap,
319				  const size_t salen, const char *hostname,
320				  const size_t hostname_len)
321{
322	struct nsm_handle *cached, *new = NULL;
323	struct lockd_net *ln = net_generic(net, lockd_net_id);
324
325	if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
326		if (printk_ratelimit()) {
327			printk(KERN_WARNING "Invalid hostname \"%.*s\" "
328					    "in NFS lock request\n",
329				(int)hostname_len, hostname);
330		}
331		return NULL;
332	}
333
334retry:
335	spin_lock(&nsm_lock);
336
337	if (nsm_use_hostnames && hostname != NULL)
338		cached = nsm_lookup_hostname(&ln->nsm_handles,
339					hostname, hostname_len);
340	else
341		cached = nsm_lookup_addr(&ln->nsm_handles, sap);
342
343	if (cached != NULL) {
344		refcount_inc(&cached->sm_count);
345		spin_unlock(&nsm_lock);
346		kfree(new);
347		dprintk("lockd: found nsm_handle for %s (%s), "
348				"cnt %d\n", cached->sm_name,
349				cached->sm_addrbuf,
350				refcount_read(&cached->sm_count));
351		return cached;
352	}
353
354	if (new != NULL) {
355		list_add(&new->sm_link, &ln->nsm_handles);
356		spin_unlock(&nsm_lock);
357		dprintk("lockd: created nsm_handle for %s (%s)\n",
358				new->sm_name, new->sm_addrbuf);
359		return new;
360	}
361
362	spin_unlock(&nsm_lock);
363
364	new = nsm_create_handle(sap, salen, hostname, hostname_len);
365	if (unlikely(new == NULL))
366		return NULL;
367	goto retry;
368}
369
370/**
371 * nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
372 * @net:  network namespace
373 * @info: pointer to NLMPROC_SM_NOTIFY arguments
374 *
375 * Returns a matching nsm_handle if found in the nsm cache. The returned
376 * nsm_handle's reference count is bumped. Otherwise returns NULL if some
377 * error occurred.
378 */
379struct nsm_handle *nsm_reboot_lookup(const struct net *net,
380				const struct nlm_reboot *info)
381{
382	struct nsm_handle *cached;
383	struct lockd_net *ln = net_generic(net, lockd_net_id);
384
385	spin_lock(&nsm_lock);
386
387	cached = nsm_lookup_priv(&ln->nsm_handles, &info->priv);
388	if (unlikely(cached == NULL)) {
389		spin_unlock(&nsm_lock);
390		dprintk("lockd: never saw rebooted peer '%.*s' before\n",
391				info->len, info->mon);
392		return cached;
393	}
394
395	refcount_inc(&cached->sm_count);
396	spin_unlock(&nsm_lock);
397
398	dprintk("lockd: host %s (%s) rebooted, cnt %d\n",
399			cached->sm_name, cached->sm_addrbuf,
400			refcount_read(&cached->sm_count));
401	return cached;
402}
403
404/**
405 * nsm_release - Release an NSM handle
406 * @nsm: pointer to handle to be released
407 *
408 */
409void nsm_release(struct nsm_handle *nsm)
410{
411	if (refcount_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
412		list_del(&nsm->sm_link);
413		spin_unlock(&nsm_lock);
414		dprintk("lockd: destroyed nsm_handle for %s (%s)\n",
415				nsm->sm_name, nsm->sm_addrbuf);
416		kfree(nsm);
417	}
418}
419
420/*
421 * XDR functions for NSM.
422 *
423 * See https://www.opengroup.org/ for details on the Network
424 * Status Monitor wire protocol.
425 */
426
427static void encode_nsm_string(struct xdr_stream *xdr, const char *string)
428{
429	const u32 len = strlen(string);
430	__be32 *p;
431
432	p = xdr_reserve_space(xdr, 4 + len);
433	xdr_encode_opaque(p, string, len);
434}
435
436/*
437 * "mon_name" specifies the host to be monitored.
438 */
439static void encode_mon_name(struct xdr_stream *xdr, const struct nsm_args *argp)
440{
441	encode_nsm_string(xdr, argp->mon_name);
442}
443
444/*
445 * The "my_id" argument specifies the hostname and RPC procedure
446 * to be called when the status manager receives notification
447 * (via the NLMPROC_SM_NOTIFY call) that the state of host "mon_name"
448 * has changed.
449 */
450static void encode_my_id(struct xdr_stream *xdr, const struct nsm_args *argp)
451{
452	__be32 *p;
453
454	encode_nsm_string(xdr, argp->nodename);
455	p = xdr_reserve_space(xdr, 4 + 4 + 4);
456	*p++ = cpu_to_be32(argp->prog);
457	*p++ = cpu_to_be32(argp->vers);
458	*p = cpu_to_be32(argp->proc);
459}
460
461/*
462 * The "mon_id" argument specifies the non-private arguments
463 * of an NSMPROC_MON or NSMPROC_UNMON call.
464 */
465static void encode_mon_id(struct xdr_stream *xdr, const struct nsm_args *argp)
466{
467	encode_mon_name(xdr, argp);
468	encode_my_id(xdr, argp);
469}
470
471/*
472 * The "priv" argument may contain private information required
473 * by the NSMPROC_MON call. This information will be supplied in the
474 * NLMPROC_SM_NOTIFY call.
475 */
476static void encode_priv(struct xdr_stream *xdr, const struct nsm_args *argp)
477{
478	__be32 *p;
479
480	p = xdr_reserve_space(xdr, SM_PRIV_SIZE);
481	xdr_encode_opaque_fixed(p, argp->priv->data, SM_PRIV_SIZE);
482}
483
484static void nsm_xdr_enc_mon(struct rpc_rqst *req, struct xdr_stream *xdr,
485			    const void *argp)
486{
487	encode_mon_id(xdr, argp);
488	encode_priv(xdr, argp);
489}
490
491static void nsm_xdr_enc_unmon(struct rpc_rqst *req, struct xdr_stream *xdr,
492			      const void *argp)
493{
494	encode_mon_id(xdr, argp);
495}
496
497static int nsm_xdr_dec_stat_res(struct rpc_rqst *rqstp,
498				struct xdr_stream *xdr,
499				void *data)
500{
501	struct nsm_res *resp = data;
502	__be32 *p;
503
504	p = xdr_inline_decode(xdr, 4 + 4);
505	if (unlikely(p == NULL))
506		return -EIO;
507	resp->status = be32_to_cpup(p++);
508	resp->state = be32_to_cpup(p);
509
510	dprintk("lockd: %s status %d state %d\n",
511		__func__, resp->status, resp->state);
512	return 0;
513}
514
515static int nsm_xdr_dec_stat(struct rpc_rqst *rqstp,
516			    struct xdr_stream *xdr,
517			    void *data)
518{
519	struct nsm_res *resp = data;
520	__be32 *p;
521
522	p = xdr_inline_decode(xdr, 4);
523	if (unlikely(p == NULL))
524		return -EIO;
525	resp->state = be32_to_cpup(p);
526
527	dprintk("lockd: %s state %d\n", __func__, resp->state);
528	return 0;
529}
530
531#define SM_my_name_sz	(1+XDR_QUADLEN(SM_MAXSTRLEN))
532#define SM_my_id_sz	(SM_my_name_sz+3)
533#define SM_mon_name_sz	(1+XDR_QUADLEN(SM_MAXSTRLEN))
534#define SM_mon_id_sz	(SM_mon_name_sz+SM_my_id_sz)
535#define SM_priv_sz	(XDR_QUADLEN(SM_PRIV_SIZE))
536#define SM_mon_sz	(SM_mon_id_sz+SM_priv_sz)
537#define SM_monres_sz	2
538#define SM_unmonres_sz	1
539
540static const struct rpc_procinfo nsm_procedures[] = {
541[NSMPROC_MON] = {
542		.p_proc		= NSMPROC_MON,
543		.p_encode	= nsm_xdr_enc_mon,
544		.p_decode	= nsm_xdr_dec_stat_res,
545		.p_arglen	= SM_mon_sz,
546		.p_replen	= SM_monres_sz,
547		.p_statidx	= NSMPROC_MON,
548		.p_name		= "MONITOR",
549	},
550[NSMPROC_UNMON] = {
551		.p_proc		= NSMPROC_UNMON,
552		.p_encode	= nsm_xdr_enc_unmon,
553		.p_decode	= nsm_xdr_dec_stat,
554		.p_arglen	= SM_mon_id_sz,
555		.p_replen	= SM_unmonres_sz,
556		.p_statidx	= NSMPROC_UNMON,
557		.p_name		= "UNMONITOR",
558	},
559};
560
561static unsigned int nsm_version1_counts[ARRAY_SIZE(nsm_procedures)];
562static const struct rpc_version nsm_version1 = {
563	.number		= 1,
564	.nrprocs	= ARRAY_SIZE(nsm_procedures),
565	.procs		= nsm_procedures,
566	.counts		= nsm_version1_counts,
567};
568
569static const struct rpc_version *nsm_version[] = {
570	[1] = &nsm_version1,
571};
572
573static struct rpc_stat		nsm_stats;
574
575static const struct rpc_program nsm_program = {
576	.name		= "statd",
577	.number		= NSM_PROGRAM,
578	.nrvers		= ARRAY_SIZE(nsm_version),
579	.version	= nsm_version,
580	.stats		= &nsm_stats
581};
582