xref: /openbmc/linux/fs/lockd/mon.c (revision de8d38cf)
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 	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  */
nsm_get_handle(const struct net * net,const struct sockaddr * sap,const size_t salen,const char * hostname,const size_t hostname_len)317 struct 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 
334 retry:
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  */
nsm_reboot_lookup(const struct net * net,const struct nlm_reboot * info)379 struct 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  */
nsm_release(struct nsm_handle * nsm)409 void 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 
encode_nsm_string(struct xdr_stream * xdr,const char * string)427 static 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  */
encode_mon_name(struct xdr_stream * xdr,const struct nsm_args * argp)439 static 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  */
encode_my_id(struct xdr_stream * xdr,const struct nsm_args * argp)450 static 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  */
encode_mon_id(struct xdr_stream * xdr,const struct nsm_args * argp)465 static 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  */
encode_priv(struct xdr_stream * xdr,const struct nsm_args * argp)476 static 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 
nsm_xdr_enc_mon(struct rpc_rqst * req,struct xdr_stream * xdr,const void * argp)484 static 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 
nsm_xdr_enc_unmon(struct rpc_rqst * req,struct xdr_stream * xdr,const void * argp)491 static 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 
nsm_xdr_dec_stat_res(struct rpc_rqst * rqstp,struct xdr_stream * xdr,void * data)497 static 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 
nsm_xdr_dec_stat(struct rpc_rqst * rqstp,struct xdr_stream * xdr,void * data)515 static 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 
540 static 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 
561 static unsigned int nsm_version1_counts[ARRAY_SIZE(nsm_procedures)];
562 static 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 
569 static const struct rpc_version *nsm_version[] = {
570 	[1] = &nsm_version1,
571 };
572 
573 static struct rpc_stat		nsm_stats;
574 
575 static 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