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 
29 enum {
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 
39 struct 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 
49 struct nsm_res {
50 	u32			status;
51 	u32			state;
52 };
53 
54 static const struct rpc_program	nsm_program;
55 static				DEFINE_SPINLOCK(nsm_lock);
56 
57 /*
58  * Local NSM state
59  */
60 u32	__read_mostly		nsm_local_state;
61 bool	__read_mostly		nsm_use_hostnames;
62 
nsm_addr(const struct nsm_handle * nsm)63 static inline struct sockaddr *nsm_addr(const struct nsm_handle *nsm)
64 {
65 	return (struct sockaddr *)&nsm->sm_addr;
66 }
67 
nsm_create(struct net * net,const char * nodename)68 static 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 
nsm_mon_unmon(struct nsm_handle * nsm,u32 proc,struct nsm_res * res,const struct nlm_host * host)91 static 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  */
nsm_monitor(const struct nlm_host * host)148 int 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  */
nsm_unmonitor(const struct nlm_host * host)189 void 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 
nsm_lookup_hostname(const struct list_head * nsm_handles,const char * hostname,const size_t len)210 static 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 
nsm_lookup_addr(const struct list_head * nsm_handles,const struct sockaddr * sap)222 static 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 
nsm_lookup_priv(const struct list_head * nsm_handles,const struct nsm_private * priv)233 static 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  */
nsm_init_private(struct nsm_handle * nsm)262 static 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 
nsm_create_handle(const struct sockaddr * sap,const size_t salen,const char * hostname,const size_t hostname_len)272 static 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 	new = kzalloc(sizeof(*new) + hostname_len + 1, GFP_KERNEL);
280 	if (unlikely(new == NULL))
281 		return NULL;
282 
283 	refcount_set(&new->sm_count, 1);
284 	new->sm_name = (char *)(new + 1);
285 	memcpy(nsm_addr(new), sap, salen);
286 	new->sm_addrlen = salen;
287 	nsm_init_private(new);
288 
289 	if (rpc_ntop(nsm_addr(new), new->sm_addrbuf,
290 					sizeof(new->sm_addrbuf)) == 0)
291 		(void)snprintf(new->sm_addrbuf, sizeof(new->sm_addrbuf),
292 				"unsupported address family");
293 	memcpy(new->sm_name, hostname, hostname_len);
294 	new->sm_name[hostname_len] = '\0';
295 
296 	return new;
297 }
298 
299 /**
300  * nsm_get_handle - Find or create a cached nsm_handle
301  * @net: network namespace
302  * @sap: pointer to socket address of handle to find
303  * @salen: length of socket address
304  * @hostname: pointer to C string containing hostname to find
305  * @hostname_len: length of C string
306  *
307  * Behavior is modulated by the global nsm_use_hostnames variable.
308  *
309  * Returns a cached nsm_handle after bumping its ref count, or
310  * returns a fresh nsm_handle if a handle that matches @sap and/or
311  * @hostname cannot be found in the handle cache.  Returns NULL if
312  * an error occurs.
313  */
nsm_get_handle(const struct net * net,const struct sockaddr * sap,const size_t salen,const char * hostname,const size_t hostname_len)314 struct nsm_handle *nsm_get_handle(const struct net *net,
315 				  const struct sockaddr *sap,
316 				  const size_t salen, const char *hostname,
317 				  const size_t hostname_len)
318 {
319 	struct nsm_handle *cached, *new = NULL;
320 	struct lockd_net *ln = net_generic(net, lockd_net_id);
321 
322 	if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
323 		if (printk_ratelimit()) {
324 			printk(KERN_WARNING "Invalid hostname \"%.*s\" "
325 					    "in NFS lock request\n",
326 				(int)hostname_len, hostname);
327 		}
328 		return NULL;
329 	}
330 
331 retry:
332 	spin_lock(&nsm_lock);
333 
334 	if (nsm_use_hostnames && hostname != NULL)
335 		cached = nsm_lookup_hostname(&ln->nsm_handles,
336 					hostname, hostname_len);
337 	else
338 		cached = nsm_lookup_addr(&ln->nsm_handles, sap);
339 
340 	if (cached != NULL) {
341 		refcount_inc(&cached->sm_count);
342 		spin_unlock(&nsm_lock);
343 		kfree(new);
344 		dprintk("lockd: found nsm_handle for %s (%s), "
345 				"cnt %d\n", cached->sm_name,
346 				cached->sm_addrbuf,
347 				refcount_read(&cached->sm_count));
348 		return cached;
349 	}
350 
351 	if (new != NULL) {
352 		list_add(&new->sm_link, &ln->nsm_handles);
353 		spin_unlock(&nsm_lock);
354 		dprintk("lockd: created nsm_handle for %s (%s)\n",
355 				new->sm_name, new->sm_addrbuf);
356 		return new;
357 	}
358 
359 	spin_unlock(&nsm_lock);
360 
361 	new = nsm_create_handle(sap, salen, hostname, hostname_len);
362 	if (unlikely(new == NULL))
363 		return NULL;
364 	goto retry;
365 }
366 
367 /**
368  * nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
369  * @net:  network namespace
370  * @info: pointer to NLMPROC_SM_NOTIFY arguments
371  *
372  * Returns a matching nsm_handle if found in the nsm cache. The returned
373  * nsm_handle's reference count is bumped. Otherwise returns NULL if some
374  * error occurred.
375  */
nsm_reboot_lookup(const struct net * net,const struct nlm_reboot * info)376 struct nsm_handle *nsm_reboot_lookup(const struct net *net,
377 				const struct nlm_reboot *info)
378 {
379 	struct nsm_handle *cached;
380 	struct lockd_net *ln = net_generic(net, lockd_net_id);
381 
382 	spin_lock(&nsm_lock);
383 
384 	cached = nsm_lookup_priv(&ln->nsm_handles, &info->priv);
385 	if (unlikely(cached == NULL)) {
386 		spin_unlock(&nsm_lock);
387 		dprintk("lockd: never saw rebooted peer '%.*s' before\n",
388 				info->len, info->mon);
389 		return cached;
390 	}
391 
392 	refcount_inc(&cached->sm_count);
393 	spin_unlock(&nsm_lock);
394 
395 	dprintk("lockd: host %s (%s) rebooted, cnt %d\n",
396 			cached->sm_name, cached->sm_addrbuf,
397 			refcount_read(&cached->sm_count));
398 	return cached;
399 }
400 
401 /**
402  * nsm_release - Release an NSM handle
403  * @nsm: pointer to handle to be released
404  *
405  */
nsm_release(struct nsm_handle * nsm)406 void nsm_release(struct nsm_handle *nsm)
407 {
408 	if (refcount_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
409 		list_del(&nsm->sm_link);
410 		spin_unlock(&nsm_lock);
411 		dprintk("lockd: destroyed nsm_handle for %s (%s)\n",
412 				nsm->sm_name, nsm->sm_addrbuf);
413 		kfree(nsm);
414 	}
415 }
416 
417 /*
418  * XDR functions for NSM.
419  *
420  * See https://www.opengroup.org/ for details on the Network
421  * Status Monitor wire protocol.
422  */
423 
encode_nsm_string(struct xdr_stream * xdr,const char * string)424 static void encode_nsm_string(struct xdr_stream *xdr, const char *string)
425 {
426 	const u32 len = strlen(string);
427 	__be32 *p;
428 
429 	p = xdr_reserve_space(xdr, 4 + len);
430 	xdr_encode_opaque(p, string, len);
431 }
432 
433 /*
434  * "mon_name" specifies the host to be monitored.
435  */
encode_mon_name(struct xdr_stream * xdr,const struct nsm_args * argp)436 static void encode_mon_name(struct xdr_stream *xdr, const struct nsm_args *argp)
437 {
438 	encode_nsm_string(xdr, argp->mon_name);
439 }
440 
441 /*
442  * The "my_id" argument specifies the hostname and RPC procedure
443  * to be called when the status manager receives notification
444  * (via the NLMPROC_SM_NOTIFY call) that the state of host "mon_name"
445  * has changed.
446  */
encode_my_id(struct xdr_stream * xdr,const struct nsm_args * argp)447 static void encode_my_id(struct xdr_stream *xdr, const struct nsm_args *argp)
448 {
449 	__be32 *p;
450 
451 	encode_nsm_string(xdr, argp->nodename);
452 	p = xdr_reserve_space(xdr, 4 + 4 + 4);
453 	*p++ = cpu_to_be32(argp->prog);
454 	*p++ = cpu_to_be32(argp->vers);
455 	*p = cpu_to_be32(argp->proc);
456 }
457 
458 /*
459  * The "mon_id" argument specifies the non-private arguments
460  * of an NSMPROC_MON or NSMPROC_UNMON call.
461  */
encode_mon_id(struct xdr_stream * xdr,const struct nsm_args * argp)462 static void encode_mon_id(struct xdr_stream *xdr, const struct nsm_args *argp)
463 {
464 	encode_mon_name(xdr, argp);
465 	encode_my_id(xdr, argp);
466 }
467 
468 /*
469  * The "priv" argument may contain private information required
470  * by the NSMPROC_MON call. This information will be supplied in the
471  * NLMPROC_SM_NOTIFY call.
472  */
encode_priv(struct xdr_stream * xdr,const struct nsm_args * argp)473 static void encode_priv(struct xdr_stream *xdr, const struct nsm_args *argp)
474 {
475 	__be32 *p;
476 
477 	p = xdr_reserve_space(xdr, SM_PRIV_SIZE);
478 	xdr_encode_opaque_fixed(p, argp->priv->data, SM_PRIV_SIZE);
479 }
480 
nsm_xdr_enc_mon(struct rpc_rqst * req,struct xdr_stream * xdr,const void * argp)481 static void nsm_xdr_enc_mon(struct rpc_rqst *req, struct xdr_stream *xdr,
482 			    const void *argp)
483 {
484 	encode_mon_id(xdr, argp);
485 	encode_priv(xdr, argp);
486 }
487 
nsm_xdr_enc_unmon(struct rpc_rqst * req,struct xdr_stream * xdr,const void * argp)488 static void nsm_xdr_enc_unmon(struct rpc_rqst *req, struct xdr_stream *xdr,
489 			      const void *argp)
490 {
491 	encode_mon_id(xdr, argp);
492 }
493 
nsm_xdr_dec_stat_res(struct rpc_rqst * rqstp,struct xdr_stream * xdr,void * data)494 static int nsm_xdr_dec_stat_res(struct rpc_rqst *rqstp,
495 				struct xdr_stream *xdr,
496 				void *data)
497 {
498 	struct nsm_res *resp = data;
499 	__be32 *p;
500 
501 	p = xdr_inline_decode(xdr, 4 + 4);
502 	if (unlikely(p == NULL))
503 		return -EIO;
504 	resp->status = be32_to_cpup(p++);
505 	resp->state = be32_to_cpup(p);
506 
507 	dprintk("lockd: %s status %d state %d\n",
508 		__func__, resp->status, resp->state);
509 	return 0;
510 }
511 
nsm_xdr_dec_stat(struct rpc_rqst * rqstp,struct xdr_stream * xdr,void * data)512 static int nsm_xdr_dec_stat(struct rpc_rqst *rqstp,
513 			    struct xdr_stream *xdr,
514 			    void *data)
515 {
516 	struct nsm_res *resp = data;
517 	__be32 *p;
518 
519 	p = xdr_inline_decode(xdr, 4);
520 	if (unlikely(p == NULL))
521 		return -EIO;
522 	resp->state = be32_to_cpup(p);
523 
524 	dprintk("lockd: %s state %d\n", __func__, resp->state);
525 	return 0;
526 }
527 
528 #define SM_my_name_sz	(1+XDR_QUADLEN(SM_MAXSTRLEN))
529 #define SM_my_id_sz	(SM_my_name_sz+3)
530 #define SM_mon_name_sz	(1+XDR_QUADLEN(SM_MAXSTRLEN))
531 #define SM_mon_id_sz	(SM_mon_name_sz+SM_my_id_sz)
532 #define SM_priv_sz	(XDR_QUADLEN(SM_PRIV_SIZE))
533 #define SM_mon_sz	(SM_mon_id_sz+SM_priv_sz)
534 #define SM_monres_sz	2
535 #define SM_unmonres_sz	1
536 
537 static const struct rpc_procinfo nsm_procedures[] = {
538 [NSMPROC_MON] = {
539 		.p_proc		= NSMPROC_MON,
540 		.p_encode	= nsm_xdr_enc_mon,
541 		.p_decode	= nsm_xdr_dec_stat_res,
542 		.p_arglen	= SM_mon_sz,
543 		.p_replen	= SM_monres_sz,
544 		.p_statidx	= NSMPROC_MON,
545 		.p_name		= "MONITOR",
546 	},
547 [NSMPROC_UNMON] = {
548 		.p_proc		= NSMPROC_UNMON,
549 		.p_encode	= nsm_xdr_enc_unmon,
550 		.p_decode	= nsm_xdr_dec_stat,
551 		.p_arglen	= SM_mon_id_sz,
552 		.p_replen	= SM_unmonres_sz,
553 		.p_statidx	= NSMPROC_UNMON,
554 		.p_name		= "UNMONITOR",
555 	},
556 };
557 
558 static unsigned int nsm_version1_counts[ARRAY_SIZE(nsm_procedures)];
559 static const struct rpc_version nsm_version1 = {
560 	.number		= 1,
561 	.nrprocs	= ARRAY_SIZE(nsm_procedures),
562 	.procs		= nsm_procedures,
563 	.counts		= nsm_version1_counts,
564 };
565 
566 static const struct rpc_version *nsm_version[] = {
567 	[1] = &nsm_version1,
568 };
569 
570 static struct rpc_stat		nsm_stats;
571 
572 static const struct rpc_program nsm_program = {
573 	.name		= "statd",
574 	.number		= NSM_PROGRAM,
575 	.nrvers		= ARRAY_SIZE(nsm_version),
576 	.version	= nsm_version,
577 	.stats		= &nsm_stats
578 };
579