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1 /*
2  * Central processing for nfsd.
3  *
4  * Authors:	Olaf Kirch (okir@monad.swb.de)
5  *
6  * Copyright (C) 1995, 1996, 1997 Olaf Kirch <okir@monad.swb.de>
7  */
8 
9 #include <linux/sched.h>
10 #include <linux/freezer.h>
11 #include <linux/module.h>
12 #include <linux/fs_struct.h>
13 #include <linux/swap.h>
14 
15 #include <linux/sunrpc/stats.h>
16 #include <linux/sunrpc/svcsock.h>
17 #include <linux/lockd/bind.h>
18 #include <linux/nfsacl.h>
19 #include <linux/seq_file.h>
20 #include <net/net_namespace.h>
21 #include "nfsd.h"
22 #include "cache.h"
23 #include "vfs.h"
24 #include "netns.h"
25 
26 #define NFSDDBG_FACILITY	NFSDDBG_SVC
27 
28 extern struct svc_program	nfsd_program;
29 static int			nfsd(void *vrqstp);
30 
31 /*
32  * nfsd_mutex protects nn->nfsd_serv -- both the pointer itself and the members
33  * of the svc_serv struct. In particular, ->sv_nrthreads but also to some
34  * extent ->sv_temp_socks and ->sv_permsocks. It also protects nfsdstats.th_cnt
35  *
36  * If (out side the lock) nn->nfsd_serv is non-NULL, then it must point to a
37  * properly initialised 'struct svc_serv' with ->sv_nrthreads > 0. That number
38  * of nfsd threads must exist and each must listed in ->sp_all_threads in each
39  * entry of ->sv_pools[].
40  *
41  * Transitions of the thread count between zero and non-zero are of particular
42  * interest since the svc_serv needs to be created and initialized at that
43  * point, or freed.
44  *
45  * Finally, the nfsd_mutex also protects some of the global variables that are
46  * accessed when nfsd starts and that are settable via the write_* routines in
47  * nfsctl.c. In particular:
48  *
49  *	user_recovery_dirname
50  *	user_lease_time
51  *	nfsd_versions
52  */
53 DEFINE_MUTEX(nfsd_mutex);
54 
55 /*
56  * nfsd_drc_lock protects nfsd_drc_max_pages and nfsd_drc_pages_used.
57  * nfsd_drc_max_pages limits the total amount of memory available for
58  * version 4.1 DRC caches.
59  * nfsd_drc_pages_used tracks the current version 4.1 DRC memory usage.
60  */
61 spinlock_t	nfsd_drc_lock;
62 unsigned long	nfsd_drc_max_mem;
63 unsigned long	nfsd_drc_mem_used;
64 
65 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
66 static struct svc_stat	nfsd_acl_svcstats;
67 static struct svc_version *	nfsd_acl_version[] = {
68 	[2] = &nfsd_acl_version2,
69 	[3] = &nfsd_acl_version3,
70 };
71 
72 #define NFSD_ACL_MINVERS            2
73 #define NFSD_ACL_NRVERS		ARRAY_SIZE(nfsd_acl_version)
74 static struct svc_version *nfsd_acl_versions[NFSD_ACL_NRVERS];
75 
76 static struct svc_program	nfsd_acl_program = {
77 	.pg_prog		= NFS_ACL_PROGRAM,
78 	.pg_nvers		= NFSD_ACL_NRVERS,
79 	.pg_vers		= nfsd_acl_versions,
80 	.pg_name		= "nfsacl",
81 	.pg_class		= "nfsd",
82 	.pg_stats		= &nfsd_acl_svcstats,
83 	.pg_authenticate	= &svc_set_client,
84 };
85 
86 static struct svc_stat	nfsd_acl_svcstats = {
87 	.program	= &nfsd_acl_program,
88 };
89 #endif /* defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL) */
90 
91 static struct svc_version *	nfsd_version[] = {
92 	[2] = &nfsd_version2,
93 #if defined(CONFIG_NFSD_V3)
94 	[3] = &nfsd_version3,
95 #endif
96 #if defined(CONFIG_NFSD_V4)
97 	[4] = &nfsd_version4,
98 #endif
99 };
100 
101 #define NFSD_MINVERS    	2
102 #define NFSD_NRVERS		ARRAY_SIZE(nfsd_version)
103 static struct svc_version *nfsd_versions[NFSD_NRVERS];
104 
105 struct svc_program		nfsd_program = {
106 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
107 	.pg_next		= &nfsd_acl_program,
108 #endif
109 	.pg_prog		= NFS_PROGRAM,		/* program number */
110 	.pg_nvers		= NFSD_NRVERS,		/* nr of entries in nfsd_version */
111 	.pg_vers		= nfsd_versions,	/* version table */
112 	.pg_name		= "nfsd",		/* program name */
113 	.pg_class		= "nfsd",		/* authentication class */
114 	.pg_stats		= &nfsd_svcstats,	/* version table */
115 	.pg_authenticate	= &svc_set_client,	/* export authentication */
116 
117 };
118 
119 static bool nfsd_supported_minorversions[NFSD_SUPPORTED_MINOR_VERSION + 1] = {
120 	[0] = 1,
121 	[1] = 1,
122 	[2] = 1,
123 };
124 
nfsd_vers(int vers,enum vers_op change)125 int nfsd_vers(int vers, enum vers_op change)
126 {
127 	if (vers < NFSD_MINVERS || vers >= NFSD_NRVERS)
128 		return 0;
129 	switch(change) {
130 	case NFSD_SET:
131 		nfsd_versions[vers] = nfsd_version[vers];
132 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
133 		if (vers < NFSD_ACL_NRVERS)
134 			nfsd_acl_versions[vers] = nfsd_acl_version[vers];
135 #endif
136 		break;
137 	case NFSD_CLEAR:
138 		nfsd_versions[vers] = NULL;
139 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
140 		if (vers < NFSD_ACL_NRVERS)
141 			nfsd_acl_versions[vers] = NULL;
142 #endif
143 		break;
144 	case NFSD_TEST:
145 		return nfsd_versions[vers] != NULL;
146 	case NFSD_AVAIL:
147 		return nfsd_version[vers] != NULL;
148 	}
149 	return 0;
150 }
151 
nfsd_minorversion(u32 minorversion,enum vers_op change)152 int nfsd_minorversion(u32 minorversion, enum vers_op change)
153 {
154 	if (minorversion > NFSD_SUPPORTED_MINOR_VERSION &&
155 	    change != NFSD_AVAIL)
156 		return -1;
157 	switch(change) {
158 	case NFSD_SET:
159 		nfsd_supported_minorversions[minorversion] = true;
160 		break;
161 	case NFSD_CLEAR:
162 		nfsd_supported_minorversions[minorversion] = false;
163 		break;
164 	case NFSD_TEST:
165 		return nfsd_supported_minorversions[minorversion];
166 	case NFSD_AVAIL:
167 		return minorversion <= NFSD_SUPPORTED_MINOR_VERSION;
168 	}
169 	return 0;
170 }
171 
172 /*
173  * Maximum number of nfsd processes
174  */
175 #define	NFSD_MAXSERVS		8192
176 
nfsd_nrthreads(struct net * net)177 int nfsd_nrthreads(struct net *net)
178 {
179 	int rv = 0;
180 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
181 
182 	mutex_lock(&nfsd_mutex);
183 	if (nn->nfsd_serv)
184 		rv = nn->nfsd_serv->sv_nrthreads;
185 	mutex_unlock(&nfsd_mutex);
186 	return rv;
187 }
188 
nfsd_init_socks(struct net * net)189 static int nfsd_init_socks(struct net *net)
190 {
191 	int error;
192 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
193 
194 	if (!list_empty(&nn->nfsd_serv->sv_permsocks))
195 		return 0;
196 
197 	error = svc_create_xprt(nn->nfsd_serv, "udp", net, PF_INET, NFS_PORT,
198 					SVC_SOCK_DEFAULTS);
199 	if (error < 0)
200 		return error;
201 
202 	error = svc_create_xprt(nn->nfsd_serv, "tcp", net, PF_INET, NFS_PORT,
203 					SVC_SOCK_DEFAULTS);
204 	if (error < 0)
205 		return error;
206 
207 	return 0;
208 }
209 
210 static int nfsd_users = 0;
211 
nfsd_startup_generic(int nrservs)212 static int nfsd_startup_generic(int nrservs)
213 {
214 	int ret;
215 
216 	if (nfsd_users++)
217 		return 0;
218 
219 	/*
220 	 * Readahead param cache - will no-op if it already exists.
221 	 * (Note therefore results will be suboptimal if number of
222 	 * threads is modified after nfsd start.)
223 	 */
224 	ret = nfsd_racache_init(2*nrservs);
225 	if (ret)
226 		goto dec_users;
227 
228 	ret = nfs4_state_start();
229 	if (ret)
230 		goto out_racache;
231 	return 0;
232 
233 out_racache:
234 	nfsd_racache_shutdown();
235 dec_users:
236 	nfsd_users--;
237 	return ret;
238 }
239 
nfsd_shutdown_generic(void)240 static void nfsd_shutdown_generic(void)
241 {
242 	if (--nfsd_users)
243 		return;
244 
245 	nfs4_state_shutdown();
246 	nfsd_racache_shutdown();
247 }
248 
nfsd_needs_lockd(void)249 static bool nfsd_needs_lockd(void)
250 {
251 #if defined(CONFIG_NFSD_V3)
252 	return (nfsd_versions[2] != NULL) || (nfsd_versions[3] != NULL);
253 #else
254 	return (nfsd_versions[2] != NULL);
255 #endif
256 }
257 
nfsd_startup_net(int nrservs,struct net * net)258 static int nfsd_startup_net(int nrservs, struct net *net)
259 {
260 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
261 	int ret;
262 
263 	if (nn->nfsd_net_up)
264 		return 0;
265 
266 	ret = nfsd_startup_generic(nrservs);
267 	if (ret)
268 		return ret;
269 	ret = nfsd_init_socks(net);
270 	if (ret)
271 		goto out_socks;
272 
273 	if (nfsd_needs_lockd() && !nn->lockd_up) {
274 		ret = lockd_up(net);
275 		if (ret)
276 			goto out_socks;
277 		nn->lockd_up = 1;
278 	}
279 
280 	ret = nfs4_state_start_net(net);
281 	if (ret)
282 		goto out_lockd;
283 
284 	nn->nfsd_net_up = true;
285 	return 0;
286 
287 out_lockd:
288 	if (nn->lockd_up) {
289 		lockd_down(net);
290 		nn->lockd_up = 0;
291 	}
292 out_socks:
293 	nfsd_shutdown_generic();
294 	return ret;
295 }
296 
nfsd_shutdown_net(struct net * net)297 static void nfsd_shutdown_net(struct net *net)
298 {
299 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
300 
301 	nfs4_state_shutdown_net(net);
302 	if (nn->lockd_up) {
303 		lockd_down(net);
304 		nn->lockd_up = 0;
305 	}
306 	nn->nfsd_net_up = false;
307 	nfsd_shutdown_generic();
308 }
309 
nfsd_last_thread(struct svc_serv * serv,struct net * net)310 static void nfsd_last_thread(struct svc_serv *serv, struct net *net)
311 {
312 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
313 
314 	/*
315 	 * write_ports can create the server without actually starting
316 	 * any threads--if we get shut down before any threads are
317 	 * started, then nfsd_last_thread will be run before any of this
318 	 * other initialization has been done.
319 	 */
320 	if (!nn->nfsd_net_up)
321 		return;
322 	nfsd_shutdown_net(net);
323 
324 	svc_rpcb_cleanup(serv, net);
325 
326 	printk(KERN_WARNING "nfsd: last server has exited, flushing export "
327 			    "cache\n");
328 	nfsd_export_flush(net);
329 }
330 
nfsd_reset_versions(void)331 void nfsd_reset_versions(void)
332 {
333 	int i;
334 
335 	for (i = 0; i < NFSD_NRVERS; i++)
336 		if (nfsd_vers(i, NFSD_TEST))
337 			return;
338 
339 	for (i = 0; i < NFSD_NRVERS; i++)
340 		if (i != 4)
341 			nfsd_vers(i, NFSD_SET);
342 		else {
343 			int minor = 0;
344 			while (nfsd_minorversion(minor, NFSD_SET) >= 0)
345 				minor++;
346 		}
347 }
348 
349 /*
350  * Each session guarantees a negotiated per slot memory cache for replies
351  * which in turn consumes memory beyond the v2/v3/v4.0 server. A dedicated
352  * NFSv4.1 server might want to use more memory for a DRC than a machine
353  * with mutiple services.
354  *
355  * Impose a hard limit on the number of pages for the DRC which varies
356  * according to the machines free pages. This is of course only a default.
357  *
358  * For now this is a #defined shift which could be under admin control
359  * in the future.
360  */
set_max_drc(void)361 static void set_max_drc(void)
362 {
363 	#define NFSD_DRC_SIZE_SHIFT	7
364 	nfsd_drc_max_mem = (nr_free_buffer_pages()
365 					>> NFSD_DRC_SIZE_SHIFT) * PAGE_SIZE;
366 	nfsd_drc_mem_used = 0;
367 	spin_lock_init(&nfsd_drc_lock);
368 	dprintk("%s nfsd_drc_max_mem %lu \n", __func__, nfsd_drc_max_mem);
369 }
370 
nfsd_get_default_max_blksize(void)371 static int nfsd_get_default_max_blksize(void)
372 {
373 	struct sysinfo i;
374 	unsigned long long target;
375 	unsigned long ret;
376 
377 	si_meminfo(&i);
378 	target = (i.totalram - i.totalhigh) << PAGE_SHIFT;
379 	/*
380 	 * Aim for 1/4096 of memory per thread This gives 1MB on 4Gig
381 	 * machines, but only uses 32K on 128M machines.  Bottom out at
382 	 * 8K on 32M and smaller.  Of course, this is only a default.
383 	 */
384 	target >>= 12;
385 
386 	ret = NFSSVC_MAXBLKSIZE;
387 	while (ret > target && ret >= 8*1024*2)
388 		ret /= 2;
389 	return ret;
390 }
391 
392 static struct svc_serv_ops nfsd_thread_sv_ops = {
393 	.svo_shutdown		= nfsd_last_thread,
394 	.svo_function		= nfsd,
395 	.svo_enqueue_xprt	= svc_xprt_do_enqueue,
396 	.svo_setup		= svc_set_num_threads,
397 	.svo_module		= THIS_MODULE,
398 };
399 
nfsd_create_serv(struct net * net)400 int nfsd_create_serv(struct net *net)
401 {
402 	int error;
403 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
404 
405 	WARN_ON(!mutex_is_locked(&nfsd_mutex));
406 	if (nn->nfsd_serv) {
407 		svc_get(nn->nfsd_serv);
408 		return 0;
409 	}
410 	if (nfsd_max_blksize == 0)
411 		nfsd_max_blksize = nfsd_get_default_max_blksize();
412 	nfsd_reset_versions();
413 	nn->nfsd_serv = svc_create_pooled(&nfsd_program, nfsd_max_blksize,
414 						&nfsd_thread_sv_ops);
415 	if (nn->nfsd_serv == NULL)
416 		return -ENOMEM;
417 
418 	nn->nfsd_serv->sv_maxconn = nn->max_connections;
419 	error = svc_bind(nn->nfsd_serv, net);
420 	if (error < 0) {
421 		svc_destroy(nn->nfsd_serv);
422 		return error;
423 	}
424 
425 	set_max_drc();
426 	do_gettimeofday(&nn->nfssvc_boot);		/* record boot time */
427 	return 0;
428 }
429 
nfsd_nrpools(struct net * net)430 int nfsd_nrpools(struct net *net)
431 {
432 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
433 
434 	if (nn->nfsd_serv == NULL)
435 		return 0;
436 	else
437 		return nn->nfsd_serv->sv_nrpools;
438 }
439 
nfsd_get_nrthreads(int n,int * nthreads,struct net * net)440 int nfsd_get_nrthreads(int n, int *nthreads, struct net *net)
441 {
442 	int i = 0;
443 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
444 
445 	if (nn->nfsd_serv != NULL) {
446 		for (i = 0; i < nn->nfsd_serv->sv_nrpools && i < n; i++)
447 			nthreads[i] = nn->nfsd_serv->sv_pools[i].sp_nrthreads;
448 	}
449 
450 	return 0;
451 }
452 
nfsd_destroy(struct net * net)453 void nfsd_destroy(struct net *net)
454 {
455 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
456 	int destroy = (nn->nfsd_serv->sv_nrthreads == 1);
457 
458 	if (destroy)
459 		svc_shutdown_net(nn->nfsd_serv, net);
460 	svc_destroy(nn->nfsd_serv);
461 	if (destroy)
462 		nn->nfsd_serv = NULL;
463 }
464 
nfsd_set_nrthreads(int n,int * nthreads,struct net * net)465 int nfsd_set_nrthreads(int n, int *nthreads, struct net *net)
466 {
467 	int i = 0;
468 	int tot = 0;
469 	int err = 0;
470 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
471 
472 	WARN_ON(!mutex_is_locked(&nfsd_mutex));
473 
474 	if (nn->nfsd_serv == NULL || n <= 0)
475 		return 0;
476 
477 	if (n > nn->nfsd_serv->sv_nrpools)
478 		n = nn->nfsd_serv->sv_nrpools;
479 
480 	/* enforce a global maximum number of threads */
481 	tot = 0;
482 	for (i = 0; i < n; i++) {
483 		nthreads[i] = min(nthreads[i], NFSD_MAXSERVS);
484 		tot += nthreads[i];
485 	}
486 	if (tot > NFSD_MAXSERVS) {
487 		/* total too large: scale down requested numbers */
488 		for (i = 0; i < n && tot > 0; i++) {
489 		    	int new = nthreads[i] * NFSD_MAXSERVS / tot;
490 			tot -= (nthreads[i] - new);
491 			nthreads[i] = new;
492 		}
493 		for (i = 0; i < n && tot > 0; i++) {
494 			nthreads[i]--;
495 			tot--;
496 		}
497 	}
498 
499 	/*
500 	 * There must always be a thread in pool 0; the admin
501 	 * can't shut down NFS completely using pool_threads.
502 	 */
503 	if (nthreads[0] == 0)
504 		nthreads[0] = 1;
505 
506 	/* apply the new numbers */
507 	svc_get(nn->nfsd_serv);
508 	for (i = 0; i < n; i++) {
509 		err = nn->nfsd_serv->sv_ops->svo_setup(nn->nfsd_serv,
510 				&nn->nfsd_serv->sv_pools[i], nthreads[i]);
511 		if (err)
512 			break;
513 	}
514 	nfsd_destroy(net);
515 	return err;
516 }
517 
518 /*
519  * Adjust the number of threads and return the new number of threads.
520  * This is also the function that starts the server if necessary, if
521  * this is the first time nrservs is nonzero.
522  */
523 int
nfsd_svc(int nrservs,struct net * net)524 nfsd_svc(int nrservs, struct net *net)
525 {
526 	int	error;
527 	bool	nfsd_up_before;
528 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
529 
530 	mutex_lock(&nfsd_mutex);
531 	dprintk("nfsd: creating service\n");
532 
533 	nrservs = max(nrservs, 0);
534 	nrservs = min(nrservs, NFSD_MAXSERVS);
535 	error = 0;
536 
537 	if (nrservs == 0 && nn->nfsd_serv == NULL)
538 		goto out;
539 
540 	error = nfsd_create_serv(net);
541 	if (error)
542 		goto out;
543 
544 	nfsd_up_before = nn->nfsd_net_up;
545 
546 	error = nfsd_startup_net(nrservs, net);
547 	if (error)
548 		goto out_destroy;
549 	error = nn->nfsd_serv->sv_ops->svo_setup(nn->nfsd_serv,
550 			NULL, nrservs);
551 	if (error)
552 		goto out_shutdown;
553 	/* We are holding a reference to nn->nfsd_serv which
554 	 * we don't want to count in the return value,
555 	 * so subtract 1
556 	 */
557 	error = nn->nfsd_serv->sv_nrthreads - 1;
558 out_shutdown:
559 	if (error < 0 && !nfsd_up_before)
560 		nfsd_shutdown_net(net);
561 out_destroy:
562 	nfsd_destroy(net);		/* Release server */
563 out:
564 	mutex_unlock(&nfsd_mutex);
565 	return error;
566 }
567 
568 
569 /*
570  * This is the NFS server kernel thread
571  */
572 static int
nfsd(void * vrqstp)573 nfsd(void *vrqstp)
574 {
575 	struct svc_rqst *rqstp = (struct svc_rqst *) vrqstp;
576 	struct svc_xprt *perm_sock = list_entry(rqstp->rq_server->sv_permsocks.next, typeof(struct svc_xprt), xpt_list);
577 	struct net *net = perm_sock->xpt_net;
578 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
579 	int err;
580 
581 	/* Lock module and set up kernel thread */
582 	mutex_lock(&nfsd_mutex);
583 
584 	/* At this point, the thread shares current->fs
585 	 * with the init process. We need to create files with a
586 	 * umask of 0 instead of init's umask. */
587 	if (unshare_fs_struct() < 0) {
588 		printk("Unable to start nfsd thread: out of memory\n");
589 		goto out;
590 	}
591 
592 	current->fs->umask = 0;
593 
594 	/*
595 	 * thread is spawned with all signals set to SIG_IGN, re-enable
596 	 * the ones that will bring down the thread
597 	 */
598 	allow_signal(SIGKILL);
599 	allow_signal(SIGHUP);
600 	allow_signal(SIGINT);
601 	allow_signal(SIGQUIT);
602 
603 	nfsdstats.th_cnt++;
604 	mutex_unlock(&nfsd_mutex);
605 
606 	set_freezable();
607 
608 	/*
609 	 * The main request loop
610 	 */
611 	for (;;) {
612 		/* Update sv_maxconn if it has changed */
613 		rqstp->rq_server->sv_maxconn = nn->max_connections;
614 
615 		/*
616 		 * Find a socket with data available and call its
617 		 * recvfrom routine.
618 		 */
619 		while ((err = svc_recv(rqstp, 60*60*HZ)) == -EAGAIN)
620 			;
621 		if (err == -EINTR)
622 			break;
623 		validate_process_creds();
624 		svc_process(rqstp);
625 		validate_process_creds();
626 	}
627 
628 	/* Clear signals before calling svc_exit_thread() */
629 	flush_signals(current);
630 
631 	mutex_lock(&nfsd_mutex);
632 	nfsdstats.th_cnt --;
633 
634 out:
635 	rqstp->rq_server = NULL;
636 
637 	/* Release the thread */
638 	svc_exit_thread(rqstp);
639 
640 	nfsd_destroy(net);
641 
642 	/* Release module */
643 	mutex_unlock(&nfsd_mutex);
644 	module_put_and_exit(0);
645 	return 0;
646 }
647 
map_new_errors(u32 vers,__be32 nfserr)648 static __be32 map_new_errors(u32 vers, __be32 nfserr)
649 {
650 	if (nfserr == nfserr_jukebox && vers == 2)
651 		return nfserr_dropit;
652 	if (nfserr == nfserr_wrongsec && vers < 4)
653 		return nfserr_acces;
654 	return nfserr;
655 }
656 
657 /*
658  * A write procedure can have a large argument, and a read procedure can
659  * have a large reply, but no NFSv2 or NFSv3 procedure has argument and
660  * reply that can both be larger than a page.  The xdr code has taken
661  * advantage of this assumption to be a sloppy about bounds checking in
662  * some cases.  Pending a rewrite of the NFSv2/v3 xdr code to fix that
663  * problem, we enforce these assumptions here:
664  */
nfs_request_too_big(struct svc_rqst * rqstp,struct svc_procedure * proc)665 static bool nfs_request_too_big(struct svc_rqst *rqstp,
666 				struct svc_procedure *proc)
667 {
668 	/*
669 	 * The ACL code has more careful bounds-checking and is not
670 	 * susceptible to this problem:
671 	 */
672 	if (rqstp->rq_prog != NFS_PROGRAM)
673 		return false;
674 	/*
675 	 * Ditto NFSv4 (which can in theory have argument and reply both
676 	 * more than a page):
677 	 */
678 	if (rqstp->rq_vers >= 4)
679 		return false;
680 	/* The reply will be small, we're OK: */
681 	if (proc->pc_xdrressize > 0 &&
682 	    proc->pc_xdrressize < XDR_QUADLEN(PAGE_SIZE))
683 		return false;
684 
685 	return rqstp->rq_arg.len > PAGE_SIZE;
686 }
687 
688 int
nfsd_dispatch(struct svc_rqst * rqstp,__be32 * statp)689 nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
690 {
691 	struct svc_procedure	*proc;
692 	kxdrproc_t		xdr;
693 	__be32			nfserr;
694 	__be32			*nfserrp;
695 
696 	dprintk("nfsd_dispatch: vers %d proc %d\n",
697 				rqstp->rq_vers, rqstp->rq_proc);
698 	proc = rqstp->rq_procinfo;
699 
700 	if (nfs_request_too_big(rqstp, proc)) {
701 		dprintk("nfsd: NFSv%d argument too large\n", rqstp->rq_vers);
702 		*statp = rpc_garbage_args;
703 		return 1;
704 	}
705 	/*
706 	 * Give the xdr decoder a chance to change this if it wants
707 	 * (necessary in the NFSv4.0 compound case)
708 	 */
709 	rqstp->rq_cachetype = proc->pc_cachetype;
710 	/* Decode arguments */
711 	xdr = proc->pc_decode;
712 	if (xdr && !xdr(rqstp, (__be32*)rqstp->rq_arg.head[0].iov_base,
713 			rqstp->rq_argp)) {
714 		dprintk("nfsd: failed to decode arguments!\n");
715 		*statp = rpc_garbage_args;
716 		return 1;
717 	}
718 
719 	/* Check whether we have this call in the cache. */
720 	switch (nfsd_cache_lookup(rqstp)) {
721 	case RC_DROPIT:
722 		return 0;
723 	case RC_REPLY:
724 		return 1;
725 	case RC_DOIT:;
726 		/* do it */
727 	}
728 
729 	/* need to grab the location to store the status, as
730 	 * nfsv4 does some encoding while processing
731 	 */
732 	nfserrp = rqstp->rq_res.head[0].iov_base
733 		+ rqstp->rq_res.head[0].iov_len;
734 	rqstp->rq_res.head[0].iov_len += sizeof(__be32);
735 
736 	/* Now call the procedure handler, and encode NFS status. */
737 	nfserr = proc->pc_func(rqstp, rqstp->rq_argp, rqstp->rq_resp);
738 	nfserr = map_new_errors(rqstp->rq_vers, nfserr);
739 	if (nfserr == nfserr_dropit || test_bit(RQ_DROPME, &rqstp->rq_flags)) {
740 		dprintk("nfsd: Dropping request; may be revisited later\n");
741 		nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
742 		return 0;
743 	}
744 
745 	if (rqstp->rq_proc != 0)
746 		*nfserrp++ = nfserr;
747 
748 	/* Encode result.
749 	 * For NFSv2, additional info is never returned in case of an error.
750 	 */
751 	if (!(nfserr && rqstp->rq_vers == 2)) {
752 		xdr = proc->pc_encode;
753 		if (xdr && !xdr(rqstp, nfserrp,
754 				rqstp->rq_resp)) {
755 			/* Failed to encode result. Release cache entry */
756 			dprintk("nfsd: failed to encode result!\n");
757 			nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
758 			*statp = rpc_system_err;
759 			return 1;
760 		}
761 	}
762 
763 	/* Store reply in cache. */
764 	nfsd_cache_update(rqstp, rqstp->rq_cachetype, statp + 1);
765 	return 1;
766 }
767 
nfsd_pool_stats_open(struct inode * inode,struct file * file)768 int nfsd_pool_stats_open(struct inode *inode, struct file *file)
769 {
770 	int ret;
771 	struct nfsd_net *nn = net_generic(inode->i_sb->s_fs_info, nfsd_net_id);
772 
773 	mutex_lock(&nfsd_mutex);
774 	if (nn->nfsd_serv == NULL) {
775 		mutex_unlock(&nfsd_mutex);
776 		return -ENODEV;
777 	}
778 	/* bump up the psudo refcount while traversing */
779 	svc_get(nn->nfsd_serv);
780 	ret = svc_pool_stats_open(nn->nfsd_serv, file);
781 	mutex_unlock(&nfsd_mutex);
782 	return ret;
783 }
784 
nfsd_pool_stats_release(struct inode * inode,struct file * file)785 int nfsd_pool_stats_release(struct inode *inode, struct file *file)
786 {
787 	int ret = seq_release(inode, file);
788 	struct net *net = inode->i_sb->s_fs_info;
789 
790 	mutex_lock(&nfsd_mutex);
791 	/* this function really, really should have been called svc_put() */
792 	nfsd_destroy(net);
793 	mutex_unlock(&nfsd_mutex);
794 	return ret;
795 }
796