xref: /openbmc/linux/fs/afs/cell.c (revision 81fc8dce)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* AFS cell and server record management
3  *
4  * Copyright (C) 2002, 2017 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  */
7 
8 #include <linux/slab.h>
9 #include <linux/key.h>
10 #include <linux/ctype.h>
11 #include <linux/dns_resolver.h>
12 #include <linux/sched.h>
13 #include <linux/inet.h>
14 #include <linux/namei.h>
15 #include <keys/rxrpc-type.h>
16 #include "internal.h"
17 
18 static unsigned __read_mostly afs_cell_gc_delay = 10;
19 static unsigned __read_mostly afs_cell_min_ttl = 10 * 60;
20 static unsigned __read_mostly afs_cell_max_ttl = 24 * 60 * 60;
21 static atomic_t cell_debug_id;
22 
23 static void afs_queue_cell_manager(struct afs_net *);
24 static void afs_manage_cell_work(struct work_struct *);
25 
afs_dec_cells_outstanding(struct afs_net * net)26 static void afs_dec_cells_outstanding(struct afs_net *net)
27 {
28 	if (atomic_dec_and_test(&net->cells_outstanding))
29 		wake_up_var(&net->cells_outstanding);
30 }
31 
32 /*
33  * Set the cell timer to fire after a given delay, assuming it's not already
34  * set for an earlier time.
35  */
afs_set_cell_timer(struct afs_net * net,time64_t delay)36 static void afs_set_cell_timer(struct afs_net *net, time64_t delay)
37 {
38 	if (net->live) {
39 		atomic_inc(&net->cells_outstanding);
40 		if (timer_reduce(&net->cells_timer, jiffies + delay * HZ))
41 			afs_dec_cells_outstanding(net);
42 	} else {
43 		afs_queue_cell_manager(net);
44 	}
45 }
46 
47 /*
48  * Look up and get an activation reference on a cell record.  The caller must
49  * hold net->cells_lock at least read-locked.
50  */
afs_find_cell_locked(struct afs_net * net,const char * name,unsigned int namesz,enum afs_cell_trace reason)51 static struct afs_cell *afs_find_cell_locked(struct afs_net *net,
52 					     const char *name, unsigned int namesz,
53 					     enum afs_cell_trace reason)
54 {
55 	struct afs_cell *cell = NULL;
56 	struct rb_node *p;
57 	int n;
58 
59 	_enter("%*.*s", namesz, namesz, name);
60 
61 	if (name && namesz == 0)
62 		return ERR_PTR(-EINVAL);
63 	if (namesz > AFS_MAXCELLNAME)
64 		return ERR_PTR(-ENAMETOOLONG);
65 
66 	if (!name) {
67 		cell = net->ws_cell;
68 		if (!cell)
69 			return ERR_PTR(-EDESTADDRREQ);
70 		goto found;
71 	}
72 
73 	p = net->cells.rb_node;
74 	while (p) {
75 		cell = rb_entry(p, struct afs_cell, net_node);
76 
77 		n = strncasecmp(cell->name, name,
78 				min_t(size_t, cell->name_len, namesz));
79 		if (n == 0)
80 			n = cell->name_len - namesz;
81 		if (n < 0)
82 			p = p->rb_left;
83 		else if (n > 0)
84 			p = p->rb_right;
85 		else
86 			goto found;
87 	}
88 
89 	return ERR_PTR(-ENOENT);
90 
91 found:
92 	return afs_use_cell(cell, reason);
93 }
94 
95 /*
96  * Look up and get an activation reference on a cell record.
97  */
afs_find_cell(struct afs_net * net,const char * name,unsigned int namesz,enum afs_cell_trace reason)98 struct afs_cell *afs_find_cell(struct afs_net *net,
99 			       const char *name, unsigned int namesz,
100 			       enum afs_cell_trace reason)
101 {
102 	struct afs_cell *cell;
103 
104 	down_read(&net->cells_lock);
105 	cell = afs_find_cell_locked(net, name, namesz, reason);
106 	up_read(&net->cells_lock);
107 	return cell;
108 }
109 
110 /*
111  * Set up a cell record and fill in its name, VL server address list and
112  * allocate an anonymous key
113  */
afs_alloc_cell(struct afs_net * net,const char * name,unsigned int namelen,const char * addresses)114 static struct afs_cell *afs_alloc_cell(struct afs_net *net,
115 				       const char *name, unsigned int namelen,
116 				       const char *addresses)
117 {
118 	struct afs_vlserver_list *vllist;
119 	struct afs_cell *cell;
120 	int i, ret;
121 
122 	ASSERT(name);
123 	if (namelen == 0)
124 		return ERR_PTR(-EINVAL);
125 	if (namelen > AFS_MAXCELLNAME) {
126 		_leave(" = -ENAMETOOLONG");
127 		return ERR_PTR(-ENAMETOOLONG);
128 	}
129 
130 	/* Prohibit cell names that contain unprintable chars, '/' and '@' or
131 	 * that begin with a dot.  This also precludes "@cell".
132 	 */
133 	if (name[0] == '.')
134 		return ERR_PTR(-EINVAL);
135 	for (i = 0; i < namelen; i++) {
136 		char ch = name[i];
137 		if (!isprint(ch) || ch == '/' || ch == '@')
138 			return ERR_PTR(-EINVAL);
139 	}
140 
141 	_enter("%*.*s,%s", namelen, namelen, name, addresses);
142 
143 	cell = kzalloc(sizeof(struct afs_cell), GFP_KERNEL);
144 	if (!cell) {
145 		_leave(" = -ENOMEM");
146 		return ERR_PTR(-ENOMEM);
147 	}
148 
149 	cell->name = kmalloc(namelen + 1, GFP_KERNEL);
150 	if (!cell->name) {
151 		kfree(cell);
152 		return ERR_PTR(-ENOMEM);
153 	}
154 
155 	cell->net = net;
156 	cell->name_len = namelen;
157 	for (i = 0; i < namelen; i++)
158 		cell->name[i] = tolower(name[i]);
159 	cell->name[i] = 0;
160 
161 	refcount_set(&cell->ref, 1);
162 	atomic_set(&cell->active, 0);
163 	INIT_WORK(&cell->manager, afs_manage_cell_work);
164 	cell->volumes = RB_ROOT;
165 	INIT_HLIST_HEAD(&cell->proc_volumes);
166 	seqlock_init(&cell->volume_lock);
167 	cell->fs_servers = RB_ROOT;
168 	seqlock_init(&cell->fs_lock);
169 	INIT_LIST_HEAD(&cell->fs_open_mmaps);
170 	init_rwsem(&cell->fs_open_mmaps_lock);
171 	rwlock_init(&cell->vl_servers_lock);
172 	cell->flags = (1 << AFS_CELL_FL_CHECK_ALIAS);
173 
174 	/* Provide a VL server list, filling it in if we were given a list of
175 	 * addresses to use.
176 	 */
177 	if (addresses) {
178 		vllist = afs_parse_text_addrs(net,
179 					      addresses, strlen(addresses), ':',
180 					      VL_SERVICE, AFS_VL_PORT);
181 		if (IS_ERR(vllist)) {
182 			ret = PTR_ERR(vllist);
183 			goto parse_failed;
184 		}
185 
186 		vllist->source = DNS_RECORD_FROM_CONFIG;
187 		vllist->status = DNS_LOOKUP_NOT_DONE;
188 		cell->dns_expiry = TIME64_MAX;
189 	} else {
190 		ret = -ENOMEM;
191 		vllist = afs_alloc_vlserver_list(0);
192 		if (!vllist)
193 			goto error;
194 		vllist->source = DNS_RECORD_UNAVAILABLE;
195 		vllist->status = DNS_LOOKUP_NOT_DONE;
196 		cell->dns_expiry = ktime_get_real_seconds();
197 	}
198 
199 	rcu_assign_pointer(cell->vl_servers, vllist);
200 
201 	cell->dns_source = vllist->source;
202 	cell->dns_status = vllist->status;
203 	smp_store_release(&cell->dns_lookup_count, 1); /* vs source/status */
204 	atomic_inc(&net->cells_outstanding);
205 	cell->debug_id = atomic_inc_return(&cell_debug_id);
206 	trace_afs_cell(cell->debug_id, 1, 0, afs_cell_trace_alloc);
207 
208 	_leave(" = %p", cell);
209 	return cell;
210 
211 parse_failed:
212 	if (ret == -EINVAL)
213 		printk(KERN_ERR "kAFS: bad VL server IP address\n");
214 error:
215 	kfree(cell->name);
216 	kfree(cell);
217 	_leave(" = %d", ret);
218 	return ERR_PTR(ret);
219 }
220 
221 /*
222  * afs_lookup_cell - Look up or create a cell record.
223  * @net:	The network namespace
224  * @name:	The name of the cell.
225  * @namesz:	The strlen of the cell name.
226  * @vllist:	A colon/comma separated list of numeric IP addresses or NULL.
227  * @excl:	T if an error should be given if the cell name already exists.
228  *
229  * Look up a cell record by name and query the DNS for VL server addresses if
230  * needed.  Note that that actual DNS query is punted off to the manager thread
231  * so that this function can return immediately if interrupted whilst allowing
232  * cell records to be shared even if not yet fully constructed.
233  */
afs_lookup_cell(struct afs_net * net,const char * name,unsigned int namesz,const char * vllist,bool excl)234 struct afs_cell *afs_lookup_cell(struct afs_net *net,
235 				 const char *name, unsigned int namesz,
236 				 const char *vllist, bool excl)
237 {
238 	struct afs_cell *cell, *candidate, *cursor;
239 	struct rb_node *parent, **pp;
240 	enum afs_cell_state state;
241 	int ret, n;
242 
243 	_enter("%s,%s", name, vllist);
244 
245 	if (!excl) {
246 		cell = afs_find_cell(net, name, namesz, afs_cell_trace_use_lookup);
247 		if (!IS_ERR(cell))
248 			goto wait_for_cell;
249 	}
250 
251 	/* Assume we're probably going to create a cell and preallocate and
252 	 * mostly set up a candidate record.  We can then use this to stash the
253 	 * name, the net namespace and VL server addresses.
254 	 *
255 	 * We also want to do this before we hold any locks as it may involve
256 	 * upcalling to userspace to make DNS queries.
257 	 */
258 	candidate = afs_alloc_cell(net, name, namesz, vllist);
259 	if (IS_ERR(candidate)) {
260 		_leave(" = %ld", PTR_ERR(candidate));
261 		return candidate;
262 	}
263 
264 	/* Find the insertion point and check to see if someone else added a
265 	 * cell whilst we were allocating.
266 	 */
267 	down_write(&net->cells_lock);
268 
269 	pp = &net->cells.rb_node;
270 	parent = NULL;
271 	while (*pp) {
272 		parent = *pp;
273 		cursor = rb_entry(parent, struct afs_cell, net_node);
274 
275 		n = strncasecmp(cursor->name, name,
276 				min_t(size_t, cursor->name_len, namesz));
277 		if (n == 0)
278 			n = cursor->name_len - namesz;
279 		if (n < 0)
280 			pp = &(*pp)->rb_left;
281 		else if (n > 0)
282 			pp = &(*pp)->rb_right;
283 		else
284 			goto cell_already_exists;
285 	}
286 
287 	cell = candidate;
288 	candidate = NULL;
289 	atomic_set(&cell->active, 2);
290 	trace_afs_cell(cell->debug_id, refcount_read(&cell->ref), 2, afs_cell_trace_insert);
291 	rb_link_node_rcu(&cell->net_node, parent, pp);
292 	rb_insert_color(&cell->net_node, &net->cells);
293 	up_write(&net->cells_lock);
294 
295 	afs_queue_cell(cell, afs_cell_trace_get_queue_new);
296 
297 wait_for_cell:
298 	trace_afs_cell(cell->debug_id, refcount_read(&cell->ref), atomic_read(&cell->active),
299 		       afs_cell_trace_wait);
300 	_debug("wait_for_cell");
301 	wait_var_event(&cell->state,
302 		       ({
303 			       state = smp_load_acquire(&cell->state); /* vs error */
304 			       state == AFS_CELL_ACTIVE || state == AFS_CELL_REMOVED;
305 		       }));
306 
307 	/* Check the state obtained from the wait check. */
308 	if (state == AFS_CELL_REMOVED) {
309 		ret = cell->error;
310 		goto error;
311 	}
312 
313 	_leave(" = %p [cell]", cell);
314 	return cell;
315 
316 cell_already_exists:
317 	_debug("cell exists");
318 	cell = cursor;
319 	if (excl) {
320 		ret = -EEXIST;
321 	} else {
322 		afs_use_cell(cursor, afs_cell_trace_use_lookup);
323 		ret = 0;
324 	}
325 	up_write(&net->cells_lock);
326 	if (candidate)
327 		afs_put_cell(candidate, afs_cell_trace_put_candidate);
328 	if (ret == 0)
329 		goto wait_for_cell;
330 	goto error_noput;
331 error:
332 	afs_unuse_cell(net, cell, afs_cell_trace_unuse_lookup);
333 error_noput:
334 	_leave(" = %d [error]", ret);
335 	return ERR_PTR(ret);
336 }
337 
338 /*
339  * set the root cell information
340  * - can be called with a module parameter string
341  * - can be called from a write to /proc/fs/afs/rootcell
342  */
afs_cell_init(struct afs_net * net,const char * rootcell)343 int afs_cell_init(struct afs_net *net, const char *rootcell)
344 {
345 	struct afs_cell *old_root, *new_root;
346 	const char *cp, *vllist;
347 	size_t len;
348 
349 	_enter("");
350 
351 	if (!rootcell) {
352 		/* module is loaded with no parameters, or built statically.
353 		 * - in the future we might initialize cell DB here.
354 		 */
355 		_leave(" = 0 [no root]");
356 		return 0;
357 	}
358 
359 	cp = strchr(rootcell, ':');
360 	if (!cp) {
361 		_debug("kAFS: no VL server IP addresses specified");
362 		vllist = NULL;
363 		len = strlen(rootcell);
364 	} else {
365 		vllist = cp + 1;
366 		len = cp - rootcell;
367 	}
368 
369 	/* allocate a cell record for the root cell */
370 	new_root = afs_lookup_cell(net, rootcell, len, vllist, false);
371 	if (IS_ERR(new_root)) {
372 		_leave(" = %ld", PTR_ERR(new_root));
373 		return PTR_ERR(new_root);
374 	}
375 
376 	if (!test_and_set_bit(AFS_CELL_FL_NO_GC, &new_root->flags))
377 		afs_use_cell(new_root, afs_cell_trace_use_pin);
378 
379 	/* install the new cell */
380 	down_write(&net->cells_lock);
381 	afs_see_cell(new_root, afs_cell_trace_see_ws);
382 	old_root = net->ws_cell;
383 	net->ws_cell = new_root;
384 	up_write(&net->cells_lock);
385 
386 	afs_unuse_cell(net, old_root, afs_cell_trace_unuse_ws);
387 	_leave(" = 0");
388 	return 0;
389 }
390 
391 /*
392  * Update a cell's VL server address list from the DNS.
393  */
afs_update_cell(struct afs_cell * cell)394 static int afs_update_cell(struct afs_cell *cell)
395 {
396 	struct afs_vlserver_list *vllist, *old = NULL, *p;
397 	unsigned int min_ttl = READ_ONCE(afs_cell_min_ttl);
398 	unsigned int max_ttl = READ_ONCE(afs_cell_max_ttl);
399 	time64_t now, expiry = 0;
400 	int ret = 0;
401 
402 	_enter("%s", cell->name);
403 
404 	vllist = afs_dns_query(cell, &expiry);
405 	if (IS_ERR(vllist)) {
406 		ret = PTR_ERR(vllist);
407 
408 		_debug("%s: fail %d", cell->name, ret);
409 		if (ret == -ENOMEM)
410 			goto out_wake;
411 
412 		vllist = afs_alloc_vlserver_list(0);
413 		if (!vllist) {
414 			if (ret >= 0)
415 				ret = -ENOMEM;
416 			goto out_wake;
417 		}
418 
419 		switch (ret) {
420 		case -ENODATA:
421 		case -EDESTADDRREQ:
422 			vllist->status = DNS_LOOKUP_GOT_NOT_FOUND;
423 			break;
424 		case -EAGAIN:
425 		case -ECONNREFUSED:
426 			vllist->status = DNS_LOOKUP_GOT_TEMP_FAILURE;
427 			break;
428 		default:
429 			vllist->status = DNS_LOOKUP_GOT_LOCAL_FAILURE;
430 			break;
431 		}
432 	}
433 
434 	_debug("%s: got list %d %d", cell->name, vllist->source, vllist->status);
435 	cell->dns_status = vllist->status;
436 
437 	now = ktime_get_real_seconds();
438 	if (min_ttl > max_ttl)
439 		max_ttl = min_ttl;
440 	if (expiry < now + min_ttl)
441 		expiry = now + min_ttl;
442 	else if (expiry > now + max_ttl)
443 		expiry = now + max_ttl;
444 
445 	_debug("%s: status %d", cell->name, vllist->status);
446 	if (vllist->source == DNS_RECORD_UNAVAILABLE) {
447 		switch (vllist->status) {
448 		case DNS_LOOKUP_GOT_NOT_FOUND:
449 			/* The DNS said that the cell does not exist or there
450 			 * weren't any addresses to be had.
451 			 */
452 			cell->dns_expiry = expiry;
453 			break;
454 
455 		case DNS_LOOKUP_BAD:
456 		case DNS_LOOKUP_GOT_LOCAL_FAILURE:
457 		case DNS_LOOKUP_GOT_TEMP_FAILURE:
458 		case DNS_LOOKUP_GOT_NS_FAILURE:
459 		default:
460 			cell->dns_expiry = now + 10;
461 			break;
462 		}
463 	} else {
464 		cell->dns_expiry = expiry;
465 	}
466 
467 	/* Replace the VL server list if the new record has servers or the old
468 	 * record doesn't.
469 	 */
470 	write_lock(&cell->vl_servers_lock);
471 	p = rcu_dereference_protected(cell->vl_servers, true);
472 	if (vllist->nr_servers > 0 || p->nr_servers == 0) {
473 		rcu_assign_pointer(cell->vl_servers, vllist);
474 		cell->dns_source = vllist->source;
475 		old = p;
476 	}
477 	write_unlock(&cell->vl_servers_lock);
478 	afs_put_vlserverlist(cell->net, old);
479 
480 out_wake:
481 	smp_store_release(&cell->dns_lookup_count,
482 			  cell->dns_lookup_count + 1); /* vs source/status */
483 	wake_up_var(&cell->dns_lookup_count);
484 	_leave(" = %d", ret);
485 	return ret;
486 }
487 
488 /*
489  * Destroy a cell record
490  */
afs_cell_destroy(struct rcu_head * rcu)491 static void afs_cell_destroy(struct rcu_head *rcu)
492 {
493 	struct afs_cell *cell = container_of(rcu, struct afs_cell, rcu);
494 	struct afs_net *net = cell->net;
495 	int r;
496 
497 	_enter("%p{%s}", cell, cell->name);
498 
499 	r = refcount_read(&cell->ref);
500 	ASSERTCMP(r, ==, 0);
501 	trace_afs_cell(cell->debug_id, r, atomic_read(&cell->active), afs_cell_trace_free);
502 
503 	afs_put_vlserverlist(net, rcu_access_pointer(cell->vl_servers));
504 	afs_unuse_cell(net, cell->alias_of, afs_cell_trace_unuse_alias);
505 	key_put(cell->anonymous_key);
506 	kfree(cell->name);
507 	kfree(cell);
508 
509 	afs_dec_cells_outstanding(net);
510 	_leave(" [destroyed]");
511 }
512 
513 /*
514  * Queue the cell manager.
515  */
afs_queue_cell_manager(struct afs_net * net)516 static void afs_queue_cell_manager(struct afs_net *net)
517 {
518 	int outstanding = atomic_inc_return(&net->cells_outstanding);
519 
520 	_enter("%d", outstanding);
521 
522 	if (!queue_work(afs_wq, &net->cells_manager))
523 		afs_dec_cells_outstanding(net);
524 }
525 
526 /*
527  * Cell management timer.  We have an increment on cells_outstanding that we
528  * need to pass along to the work item.
529  */
afs_cells_timer(struct timer_list * timer)530 void afs_cells_timer(struct timer_list *timer)
531 {
532 	struct afs_net *net = container_of(timer, struct afs_net, cells_timer);
533 
534 	_enter("");
535 	if (!queue_work(afs_wq, &net->cells_manager))
536 		afs_dec_cells_outstanding(net);
537 }
538 
539 /*
540  * Get a reference on a cell record.
541  */
afs_get_cell(struct afs_cell * cell,enum afs_cell_trace reason)542 struct afs_cell *afs_get_cell(struct afs_cell *cell, enum afs_cell_trace reason)
543 {
544 	int r;
545 
546 	__refcount_inc(&cell->ref, &r);
547 	trace_afs_cell(cell->debug_id, r + 1, atomic_read(&cell->active), reason);
548 	return cell;
549 }
550 
551 /*
552  * Drop a reference on a cell record.
553  */
afs_put_cell(struct afs_cell * cell,enum afs_cell_trace reason)554 void afs_put_cell(struct afs_cell *cell, enum afs_cell_trace reason)
555 {
556 	if (cell) {
557 		unsigned int debug_id = cell->debug_id;
558 		unsigned int a;
559 		bool zero;
560 		int r;
561 
562 		a = atomic_read(&cell->active);
563 		zero = __refcount_dec_and_test(&cell->ref, &r);
564 		trace_afs_cell(debug_id, r - 1, a, reason);
565 		if (zero) {
566 			a = atomic_read(&cell->active);
567 			WARN(a != 0, "Cell active count %u > 0\n", a);
568 			call_rcu(&cell->rcu, afs_cell_destroy);
569 		}
570 	}
571 }
572 
573 /*
574  * Note a cell becoming more active.
575  */
afs_use_cell(struct afs_cell * cell,enum afs_cell_trace reason)576 struct afs_cell *afs_use_cell(struct afs_cell *cell, enum afs_cell_trace reason)
577 {
578 	int r, a;
579 
580 	r = refcount_read(&cell->ref);
581 	WARN_ON(r == 0);
582 	a = atomic_inc_return(&cell->active);
583 	trace_afs_cell(cell->debug_id, r, a, reason);
584 	return cell;
585 }
586 
587 /*
588  * Record a cell becoming less active.  When the active counter reaches 1, it
589  * is scheduled for destruction, but may get reactivated.
590  */
afs_unuse_cell(struct afs_net * net,struct afs_cell * cell,enum afs_cell_trace reason)591 void afs_unuse_cell(struct afs_net *net, struct afs_cell *cell, enum afs_cell_trace reason)
592 {
593 	unsigned int debug_id;
594 	time64_t now, expire_delay;
595 	int r, a;
596 
597 	if (!cell)
598 		return;
599 
600 	_enter("%s", cell->name);
601 
602 	now = ktime_get_real_seconds();
603 	cell->last_inactive = now;
604 	expire_delay = 0;
605 	if (cell->vl_servers->nr_servers)
606 		expire_delay = afs_cell_gc_delay;
607 
608 	debug_id = cell->debug_id;
609 	r = refcount_read(&cell->ref);
610 	a = atomic_dec_return(&cell->active);
611 	trace_afs_cell(debug_id, r, a, reason);
612 	WARN_ON(a == 0);
613 	if (a == 1)
614 		/* 'cell' may now be garbage collected. */
615 		afs_set_cell_timer(net, expire_delay);
616 }
617 
618 /*
619  * Note that a cell has been seen.
620  */
afs_see_cell(struct afs_cell * cell,enum afs_cell_trace reason)621 void afs_see_cell(struct afs_cell *cell, enum afs_cell_trace reason)
622 {
623 	int r, a;
624 
625 	r = refcount_read(&cell->ref);
626 	a = atomic_read(&cell->active);
627 	trace_afs_cell(cell->debug_id, r, a, reason);
628 }
629 
630 /*
631  * Queue a cell for management, giving the workqueue a ref to hold.
632  */
afs_queue_cell(struct afs_cell * cell,enum afs_cell_trace reason)633 void afs_queue_cell(struct afs_cell *cell, enum afs_cell_trace reason)
634 {
635 	afs_get_cell(cell, reason);
636 	if (!queue_work(afs_wq, &cell->manager))
637 		afs_put_cell(cell, afs_cell_trace_put_queue_fail);
638 }
639 
640 /*
641  * Allocate a key to use as a placeholder for anonymous user security.
642  */
afs_alloc_anon_key(struct afs_cell * cell)643 static int afs_alloc_anon_key(struct afs_cell *cell)
644 {
645 	struct key *key;
646 	char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp;
647 
648 	/* Create a key to represent an anonymous user. */
649 	memcpy(keyname, "afs@", 4);
650 	dp = keyname + 4;
651 	cp = cell->name;
652 	do {
653 		*dp++ = tolower(*cp);
654 	} while (*cp++);
655 
656 	key = rxrpc_get_null_key(keyname);
657 	if (IS_ERR(key))
658 		return PTR_ERR(key);
659 
660 	cell->anonymous_key = key;
661 
662 	_debug("anon key %p{%x}",
663 	       cell->anonymous_key, key_serial(cell->anonymous_key));
664 	return 0;
665 }
666 
667 /*
668  * Activate a cell.
669  */
afs_activate_cell(struct afs_net * net,struct afs_cell * cell)670 static int afs_activate_cell(struct afs_net *net, struct afs_cell *cell)
671 {
672 	struct hlist_node **p;
673 	struct afs_cell *pcell;
674 	int ret;
675 
676 	if (!cell->anonymous_key) {
677 		ret = afs_alloc_anon_key(cell);
678 		if (ret < 0)
679 			return ret;
680 	}
681 
682 	ret = afs_proc_cell_setup(cell);
683 	if (ret < 0)
684 		return ret;
685 
686 	mutex_lock(&net->proc_cells_lock);
687 	for (p = &net->proc_cells.first; *p; p = &(*p)->next) {
688 		pcell = hlist_entry(*p, struct afs_cell, proc_link);
689 		if (strcmp(cell->name, pcell->name) < 0)
690 			break;
691 	}
692 
693 	cell->proc_link.pprev = p;
694 	cell->proc_link.next = *p;
695 	rcu_assign_pointer(*p, &cell->proc_link.next);
696 	if (cell->proc_link.next)
697 		cell->proc_link.next->pprev = &cell->proc_link.next;
698 
699 	afs_dynroot_mkdir(net, cell);
700 	mutex_unlock(&net->proc_cells_lock);
701 	return 0;
702 }
703 
704 /*
705  * Deactivate a cell.
706  */
afs_deactivate_cell(struct afs_net * net,struct afs_cell * cell)707 static void afs_deactivate_cell(struct afs_net *net, struct afs_cell *cell)
708 {
709 	_enter("%s", cell->name);
710 
711 	afs_proc_cell_remove(cell);
712 
713 	mutex_lock(&net->proc_cells_lock);
714 	hlist_del_rcu(&cell->proc_link);
715 	afs_dynroot_rmdir(net, cell);
716 	mutex_unlock(&net->proc_cells_lock);
717 
718 	_leave("");
719 }
720 
721 /*
722  * Manage a cell record, initialising and destroying it, maintaining its DNS
723  * records.
724  */
afs_manage_cell(struct afs_cell * cell)725 static void afs_manage_cell(struct afs_cell *cell)
726 {
727 	struct afs_net *net = cell->net;
728 	int ret, active;
729 
730 	_enter("%s", cell->name);
731 
732 again:
733 	_debug("state %u", cell->state);
734 	switch (cell->state) {
735 	case AFS_CELL_INACTIVE:
736 	case AFS_CELL_FAILED:
737 		down_write(&net->cells_lock);
738 		active = 1;
739 		if (atomic_try_cmpxchg_relaxed(&cell->active, &active, 0)) {
740 			rb_erase(&cell->net_node, &net->cells);
741 			trace_afs_cell(cell->debug_id, refcount_read(&cell->ref), 0,
742 				       afs_cell_trace_unuse_delete);
743 			smp_store_release(&cell->state, AFS_CELL_REMOVED);
744 		}
745 		up_write(&net->cells_lock);
746 		if (cell->state == AFS_CELL_REMOVED) {
747 			wake_up_var(&cell->state);
748 			goto final_destruction;
749 		}
750 		if (cell->state == AFS_CELL_FAILED)
751 			goto done;
752 		smp_store_release(&cell->state, AFS_CELL_UNSET);
753 		wake_up_var(&cell->state);
754 		goto again;
755 
756 	case AFS_CELL_UNSET:
757 		smp_store_release(&cell->state, AFS_CELL_ACTIVATING);
758 		wake_up_var(&cell->state);
759 		goto again;
760 
761 	case AFS_CELL_ACTIVATING:
762 		ret = afs_activate_cell(net, cell);
763 		if (ret < 0)
764 			goto activation_failed;
765 
766 		smp_store_release(&cell->state, AFS_CELL_ACTIVE);
767 		wake_up_var(&cell->state);
768 		goto again;
769 
770 	case AFS_CELL_ACTIVE:
771 		if (atomic_read(&cell->active) > 1) {
772 			if (test_and_clear_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags)) {
773 				ret = afs_update_cell(cell);
774 				if (ret < 0)
775 					cell->error = ret;
776 			}
777 			goto done;
778 		}
779 		smp_store_release(&cell->state, AFS_CELL_DEACTIVATING);
780 		wake_up_var(&cell->state);
781 		goto again;
782 
783 	case AFS_CELL_DEACTIVATING:
784 		if (atomic_read(&cell->active) > 1)
785 			goto reverse_deactivation;
786 		afs_deactivate_cell(net, cell);
787 		smp_store_release(&cell->state, AFS_CELL_INACTIVE);
788 		wake_up_var(&cell->state);
789 		goto again;
790 
791 	case AFS_CELL_REMOVED:
792 		goto done;
793 
794 	default:
795 		break;
796 	}
797 	_debug("bad state %u", cell->state);
798 	BUG(); /* Unhandled state */
799 
800 activation_failed:
801 	cell->error = ret;
802 	afs_deactivate_cell(net, cell);
803 
804 	smp_store_release(&cell->state, AFS_CELL_FAILED); /* vs error */
805 	wake_up_var(&cell->state);
806 	goto again;
807 
808 reverse_deactivation:
809 	smp_store_release(&cell->state, AFS_CELL_ACTIVE);
810 	wake_up_var(&cell->state);
811 	_leave(" [deact->act]");
812 	return;
813 
814 done:
815 	_leave(" [done %u]", cell->state);
816 	return;
817 
818 final_destruction:
819 	/* The root volume is pinning the cell */
820 	afs_put_volume(cell->net, cell->root_volume, afs_volume_trace_put_cell_root);
821 	cell->root_volume = NULL;
822 	afs_put_cell(cell, afs_cell_trace_put_destroy);
823 }
824 
afs_manage_cell_work(struct work_struct * work)825 static void afs_manage_cell_work(struct work_struct *work)
826 {
827 	struct afs_cell *cell = container_of(work, struct afs_cell, manager);
828 
829 	afs_manage_cell(cell);
830 	afs_put_cell(cell, afs_cell_trace_put_queue_work);
831 }
832 
833 /*
834  * Manage the records of cells known to a network namespace.  This includes
835  * updating the DNS records and garbage collecting unused cells that were
836  * automatically added.
837  *
838  * Note that constructed cell records may only be removed from net->cells by
839  * this work item, so it is safe for this work item to stash a cursor pointing
840  * into the tree and then return to caller (provided it skips cells that are
841  * still under construction).
842  *
843  * Note also that we were given an increment on net->cells_outstanding by
844  * whoever queued us that we need to deal with before returning.
845  */
afs_manage_cells(struct work_struct * work)846 void afs_manage_cells(struct work_struct *work)
847 {
848 	struct afs_net *net = container_of(work, struct afs_net, cells_manager);
849 	struct rb_node *cursor;
850 	time64_t now = ktime_get_real_seconds(), next_manage = TIME64_MAX;
851 	bool purging = !net->live;
852 
853 	_enter("");
854 
855 	/* Trawl the cell database looking for cells that have expired from
856 	 * lack of use and cells whose DNS results have expired and dispatch
857 	 * their managers.
858 	 */
859 	down_read(&net->cells_lock);
860 
861 	for (cursor = rb_first(&net->cells); cursor; cursor = rb_next(cursor)) {
862 		struct afs_cell *cell =
863 			rb_entry(cursor, struct afs_cell, net_node);
864 		unsigned active;
865 		bool sched_cell = false;
866 
867 		active = atomic_read(&cell->active);
868 		trace_afs_cell(cell->debug_id, refcount_read(&cell->ref),
869 			       active, afs_cell_trace_manage);
870 
871 		ASSERTCMP(active, >=, 1);
872 
873 		if (purging) {
874 			if (test_and_clear_bit(AFS_CELL_FL_NO_GC, &cell->flags)) {
875 				active = atomic_dec_return(&cell->active);
876 				trace_afs_cell(cell->debug_id, refcount_read(&cell->ref),
877 					       active, afs_cell_trace_unuse_pin);
878 			}
879 		}
880 
881 		if (active == 1) {
882 			struct afs_vlserver_list *vllist;
883 			time64_t expire_at = cell->last_inactive;
884 
885 			read_lock(&cell->vl_servers_lock);
886 			vllist = rcu_dereference_protected(
887 				cell->vl_servers,
888 				lockdep_is_held(&cell->vl_servers_lock));
889 			if (vllist->nr_servers > 0)
890 				expire_at += afs_cell_gc_delay;
891 			read_unlock(&cell->vl_servers_lock);
892 			if (purging || expire_at <= now)
893 				sched_cell = true;
894 			else if (expire_at < next_manage)
895 				next_manage = expire_at;
896 		}
897 
898 		if (!purging) {
899 			if (test_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags))
900 				sched_cell = true;
901 		}
902 
903 		if (sched_cell)
904 			afs_queue_cell(cell, afs_cell_trace_get_queue_manage);
905 	}
906 
907 	up_read(&net->cells_lock);
908 
909 	/* Update the timer on the way out.  We have to pass an increment on
910 	 * cells_outstanding in the namespace that we are in to the timer or
911 	 * the work scheduler.
912 	 */
913 	if (!purging && next_manage < TIME64_MAX) {
914 		now = ktime_get_real_seconds();
915 
916 		if (next_manage - now <= 0) {
917 			if (queue_work(afs_wq, &net->cells_manager))
918 				atomic_inc(&net->cells_outstanding);
919 		} else {
920 			afs_set_cell_timer(net, next_manage - now);
921 		}
922 	}
923 
924 	afs_dec_cells_outstanding(net);
925 	_leave(" [%d]", atomic_read(&net->cells_outstanding));
926 }
927 
928 /*
929  * Purge in-memory cell database.
930  */
afs_cell_purge(struct afs_net * net)931 void afs_cell_purge(struct afs_net *net)
932 {
933 	struct afs_cell *ws;
934 
935 	_enter("");
936 
937 	down_write(&net->cells_lock);
938 	ws = net->ws_cell;
939 	net->ws_cell = NULL;
940 	up_write(&net->cells_lock);
941 	afs_unuse_cell(net, ws, afs_cell_trace_unuse_ws);
942 
943 	_debug("del timer");
944 	if (del_timer_sync(&net->cells_timer))
945 		atomic_dec(&net->cells_outstanding);
946 
947 	_debug("kick mgr");
948 	afs_queue_cell_manager(net);
949 
950 	_debug("wait");
951 	wait_var_event(&net->cells_outstanding,
952 		       !atomic_read(&net->cells_outstanding));
953 	_leave("");
954 }
955