xref: /openbmc/linux/fs/autofs/root.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /* -*- linux-c -*- --------------------------------------------------------- *
2  *
3  * linux/fs/autofs/root.c
4  *
5  *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
6  *
7  * This file is part of the Linux kernel and is made available under
8  * the terms of the GNU General Public License, version 2, or at your
9  * option, any later version, incorporated herein by reference.
10  *
11  * ------------------------------------------------------------------------- */
12 
13 #include <linux/errno.h>
14 #include <linux/stat.h>
15 #include <linux/param.h>
16 #include <linux/time.h>
17 #include <linux/smp_lock.h>
18 #include "autofs_i.h"
19 
20 static int autofs_root_readdir(struct file *,void *,filldir_t);
21 static struct dentry *autofs_root_lookup(struct inode *,struct dentry *, struct nameidata *);
22 static int autofs_root_symlink(struct inode *,struct dentry *,const char *);
23 static int autofs_root_unlink(struct inode *,struct dentry *);
24 static int autofs_root_rmdir(struct inode *,struct dentry *);
25 static int autofs_root_mkdir(struct inode *,struct dentry *,int);
26 static int autofs_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
27 
28 struct file_operations autofs_root_operations = {
29 	.read		= generic_read_dir,
30 	.readdir	= autofs_root_readdir,
31 	.ioctl		= autofs_root_ioctl,
32 };
33 
34 struct inode_operations autofs_root_inode_operations = {
35         .lookup		= autofs_root_lookup,
36         .unlink		= autofs_root_unlink,
37         .symlink	= autofs_root_symlink,
38         .mkdir		= autofs_root_mkdir,
39         .rmdir		= autofs_root_rmdir,
40 };
41 
42 static int autofs_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
43 {
44 	struct autofs_dir_ent *ent = NULL;
45 	struct autofs_dirhash *dirhash;
46 	struct autofs_sb_info *sbi;
47 	struct inode * inode = filp->f_dentry->d_inode;
48 	off_t onr, nr;
49 
50 	lock_kernel();
51 
52 	sbi = autofs_sbi(inode->i_sb);
53 	dirhash = &sbi->dirhash;
54 	nr = filp->f_pos;
55 
56 	switch(nr)
57 	{
58 	case 0:
59 		if (filldir(dirent, ".", 1, nr, inode->i_ino, DT_DIR) < 0)
60 			goto out;
61 		filp->f_pos = ++nr;
62 		/* fall through */
63 	case 1:
64 		if (filldir(dirent, "..", 2, nr, inode->i_ino, DT_DIR) < 0)
65 			goto out;
66 		filp->f_pos = ++nr;
67 		/* fall through */
68 	default:
69 		while ( onr = nr, ent = autofs_hash_enum(dirhash,&nr,ent) ) {
70 			if ( !ent->dentry || d_mountpoint(ent->dentry) ) {
71 				if (filldir(dirent,ent->name,ent->len,onr,ent->ino,DT_UNKNOWN) < 0)
72 					goto out;
73 				filp->f_pos = nr;
74 			}
75 		}
76 		break;
77 	}
78 
79 out:
80 	unlock_kernel();
81 	return 0;
82 }
83 
84 static int try_to_fill_dentry(struct dentry *dentry, struct super_block *sb, struct autofs_sb_info *sbi)
85 {
86 	struct inode * inode;
87 	struct autofs_dir_ent *ent;
88 	int status = 0;
89 
90 	if ( !(ent = autofs_hash_lookup(&sbi->dirhash, &dentry->d_name)) ) {
91 		do {
92 			if ( status && dentry->d_inode ) {
93 				if ( status != -ENOENT )
94 					printk("autofs warning: lookup failure on positive dentry, status = %d, name = %s\n", status, dentry->d_name.name);
95 				return 0; /* Try to get the kernel to invalidate this dentry */
96 			}
97 
98 			/* Turn this into a real negative dentry? */
99 			if (status == -ENOENT) {
100 				dentry->d_time = jiffies + AUTOFS_NEGATIVE_TIMEOUT;
101 				dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
102 				return 1;
103 			} else if (status) {
104 				/* Return a negative dentry, but leave it "pending" */
105 				return 1;
106 			}
107 			status = autofs_wait(sbi, &dentry->d_name);
108 		} while (!(ent = autofs_hash_lookup(&sbi->dirhash, &dentry->d_name)) );
109 	}
110 
111 	/* Abuse this field as a pointer to the directory entry, used to
112 	   find the expire list pointers */
113 	dentry->d_time = (unsigned long) ent;
114 
115 	if (!dentry->d_inode) {
116 		inode = iget(sb, ent->ino);
117 		if (!inode) {
118 			/* Failed, but leave pending for next time */
119 			return 1;
120 		}
121 		dentry->d_inode = inode;
122 	}
123 
124 	/* If this is a directory that isn't a mount point, bitch at the
125 	   daemon and fix it in user space */
126 	if ( S_ISDIR(dentry->d_inode->i_mode) && !d_mountpoint(dentry) ) {
127 		return !autofs_wait(sbi, &dentry->d_name);
128 	}
129 
130 	/* We don't update the usages for the autofs daemon itself, this
131 	   is necessary for recursive autofs mounts */
132 	if ( !autofs_oz_mode(sbi) ) {
133 		autofs_update_usage(&sbi->dirhash,ent);
134 	}
135 
136 	dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
137 	return 1;
138 }
139 
140 
141 /*
142  * Revalidate is called on every cache lookup.  Some of those
143  * cache lookups may actually happen while the dentry is not
144  * yet completely filled in, and revalidate has to delay such
145  * lookups..
146  */
147 static int autofs_revalidate(struct dentry * dentry, struct nameidata *nd)
148 {
149 	struct inode * dir;
150 	struct autofs_sb_info *sbi;
151 	struct autofs_dir_ent *ent;
152 	int res;
153 
154 	lock_kernel();
155 	dir = dentry->d_parent->d_inode;
156 	sbi = autofs_sbi(dir->i_sb);
157 
158 	/* Pending dentry */
159 	if ( dentry->d_flags & DCACHE_AUTOFS_PENDING ) {
160 		if (autofs_oz_mode(sbi))
161 			res = 1;
162 		else
163 			res = try_to_fill_dentry(dentry, dir->i_sb, sbi);
164 		unlock_kernel();
165 		return res;
166 	}
167 
168 	/* Negative dentry.. invalidate if "old" */
169 	if (!dentry->d_inode) {
170 		unlock_kernel();
171 		return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);
172 	}
173 
174 	/* Check for a non-mountpoint directory */
175 	if ( S_ISDIR(dentry->d_inode->i_mode) && !d_mountpoint(dentry) ) {
176 		if (autofs_oz_mode(sbi))
177 			res = 1;
178 		else
179 			res = try_to_fill_dentry(dentry, dir->i_sb, sbi);
180 		unlock_kernel();
181 		return res;
182 	}
183 
184 	/* Update the usage list */
185 	if ( !autofs_oz_mode(sbi) ) {
186 		ent = (struct autofs_dir_ent *) dentry->d_time;
187 		if ( ent )
188 			autofs_update_usage(&sbi->dirhash,ent);
189 	}
190 	unlock_kernel();
191 	return 1;
192 }
193 
194 static struct dentry_operations autofs_dentry_operations = {
195 	.d_revalidate	= autofs_revalidate,
196 };
197 
198 static struct dentry *autofs_root_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
199 {
200 	struct autofs_sb_info *sbi;
201 	int oz_mode;
202 
203 	DPRINTK(("autofs_root_lookup: name = "));
204 	lock_kernel();
205 	autofs_say(dentry->d_name.name,dentry->d_name.len);
206 
207 	if (dentry->d_name.len > NAME_MAX) {
208 		unlock_kernel();
209 		return ERR_PTR(-ENAMETOOLONG);/* File name too long to exist */
210 	}
211 
212 	sbi = autofs_sbi(dir->i_sb);
213 
214 	oz_mode = autofs_oz_mode(sbi);
215 	DPRINTK(("autofs_lookup: pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n",
216 		 current->pid, process_group(current), sbi->catatonic, oz_mode));
217 
218 	/*
219 	 * Mark the dentry incomplete, but add it. This is needed so
220 	 * that the VFS layer knows about the dentry, and we can count
221 	 * on catching any lookups through the revalidate.
222 	 *
223 	 * Let all the hard work be done by the revalidate function that
224 	 * needs to be able to do this anyway..
225 	 *
226 	 * We need to do this before we release the directory semaphore.
227 	 */
228 	dentry->d_op = &autofs_dentry_operations;
229 	dentry->d_flags |= DCACHE_AUTOFS_PENDING;
230 	d_add(dentry, NULL);
231 
232 	up(&dir->i_sem);
233 	autofs_revalidate(dentry, nd);
234 	down(&dir->i_sem);
235 
236 	/*
237 	 * If we are still pending, check if we had to handle
238 	 * a signal. If so we can force a restart..
239 	 */
240 	if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
241 		/* See if we were interrupted */
242 		if (signal_pending(current)) {
243 			sigset_t *sigset = &current->pending.signal;
244 			if (sigismember (sigset, SIGKILL) ||
245 			    sigismember (sigset, SIGQUIT) ||
246 			    sigismember (sigset, SIGINT)) {
247 				unlock_kernel();
248 				return ERR_PTR(-ERESTARTNOINTR);
249 			}
250 		}
251 	}
252 	unlock_kernel();
253 
254 	/*
255 	 * If this dentry is unhashed, then we shouldn't honour this
256 	 * lookup even if the dentry is positive.  Returning ENOENT here
257 	 * doesn't do the right thing for all system calls, but it should
258 	 * be OK for the operations we permit from an autofs.
259 	 */
260 	if ( dentry->d_inode && d_unhashed(dentry) )
261 		return ERR_PTR(-ENOENT);
262 
263 	return NULL;
264 }
265 
266 static int autofs_root_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
267 {
268 	struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
269 	struct autofs_dirhash *dh = &sbi->dirhash;
270 	struct autofs_dir_ent *ent;
271 	unsigned int n;
272 	int slsize;
273 	struct autofs_symlink *sl;
274 
275 	DPRINTK(("autofs_root_symlink: %s <- ", symname));
276 	autofs_say(dentry->d_name.name,dentry->d_name.len);
277 
278 	lock_kernel();
279 	if ( !autofs_oz_mode(sbi) ) {
280 		unlock_kernel();
281 		return -EACCES;
282 	}
283 
284 	if ( autofs_hash_lookup(dh, &dentry->d_name) ) {
285 		unlock_kernel();
286 		return -EEXIST;
287 	}
288 
289 	n = find_first_zero_bit(sbi->symlink_bitmap,AUTOFS_MAX_SYMLINKS);
290 	if ( n >= AUTOFS_MAX_SYMLINKS ) {
291 		unlock_kernel();
292 		return -ENOSPC;
293 	}
294 
295 	set_bit(n,sbi->symlink_bitmap);
296 	sl = &sbi->symlink[n];
297 	sl->len = strlen(symname);
298 	sl->data = kmalloc(slsize = sl->len+1, GFP_KERNEL);
299 	if ( !sl->data ) {
300 		clear_bit(n,sbi->symlink_bitmap);
301 		unlock_kernel();
302 		return -ENOSPC;
303 	}
304 
305 	ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
306 	if ( !ent ) {
307 		kfree(sl->data);
308 		clear_bit(n,sbi->symlink_bitmap);
309 		unlock_kernel();
310 		return -ENOSPC;
311 	}
312 
313 	ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
314 	if ( !ent->name ) {
315 		kfree(sl->data);
316 		kfree(ent);
317 		clear_bit(n,sbi->symlink_bitmap);
318 		unlock_kernel();
319 		return -ENOSPC;
320 	}
321 
322 	memcpy(sl->data,symname,slsize);
323 	sl->mtime = get_seconds();
324 
325 	ent->ino = AUTOFS_FIRST_SYMLINK + n;
326 	ent->hash = dentry->d_name.hash;
327 	memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
328 	ent->dentry = NULL;	/* We don't keep the dentry for symlinks */
329 
330 	autofs_hash_insert(dh,ent);
331 	d_instantiate(dentry, iget(dir->i_sb,ent->ino));
332 	unlock_kernel();
333 	return 0;
334 }
335 
336 /*
337  * NOTE!
338  *
339  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
340  * that the file no longer exists. However, doing that means that the
341  * VFS layer can turn the dentry into a negative dentry, which we
342  * obviously do not want (we're dropping the entry not because it
343  * doesn't exist, but because it has timed out).
344  *
345  * Also see autofs_root_rmdir()..
346  */
347 static int autofs_root_unlink(struct inode *dir, struct dentry *dentry)
348 {
349 	struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
350 	struct autofs_dirhash *dh = &sbi->dirhash;
351 	struct autofs_dir_ent *ent;
352 	unsigned int n;
353 
354 	/* This allows root to remove symlinks */
355 	lock_kernel();
356 	if ( !autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) ) {
357 		unlock_kernel();
358 		return -EACCES;
359 	}
360 
361 	ent = autofs_hash_lookup(dh, &dentry->d_name);
362 	if ( !ent ) {
363 		unlock_kernel();
364 		return -ENOENT;
365 	}
366 
367 	n = ent->ino - AUTOFS_FIRST_SYMLINK;
368 	if ( n >= AUTOFS_MAX_SYMLINKS ) {
369 		unlock_kernel();
370 		return -EISDIR;	/* It's a directory, dummy */
371 	}
372 	if ( !test_bit(n,sbi->symlink_bitmap) ) {
373 		unlock_kernel();
374 		return -EINVAL;	/* Nonexistent symlink?  Shouldn't happen */
375 	}
376 
377 	dentry->d_time = (unsigned long)(struct autofs_dirhash *)NULL;
378 	autofs_hash_delete(ent);
379 	clear_bit(n,sbi->symlink_bitmap);
380 	kfree(sbi->symlink[n].data);
381 	d_drop(dentry);
382 
383 	unlock_kernel();
384 	return 0;
385 }
386 
387 static int autofs_root_rmdir(struct inode *dir, struct dentry *dentry)
388 {
389 	struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
390 	struct autofs_dirhash *dh = &sbi->dirhash;
391 	struct autofs_dir_ent *ent;
392 
393 	lock_kernel();
394 	if ( !autofs_oz_mode(sbi) ) {
395 		unlock_kernel();
396 		return -EACCES;
397 	}
398 
399 	ent = autofs_hash_lookup(dh, &dentry->d_name);
400 	if ( !ent ) {
401 		unlock_kernel();
402 		return -ENOENT;
403 	}
404 
405 	if ( (unsigned int)ent->ino < AUTOFS_FIRST_DIR_INO ) {
406 		unlock_kernel();
407 		return -ENOTDIR; /* Not a directory */
408 	}
409 
410 	if ( ent->dentry != dentry ) {
411 		printk("autofs_rmdir: odentry != dentry for entry %s\n", dentry->d_name.name);
412 	}
413 
414 	dentry->d_time = (unsigned long)(struct autofs_dir_ent *)NULL;
415 	autofs_hash_delete(ent);
416 	dir->i_nlink--;
417 	d_drop(dentry);
418 	unlock_kernel();
419 
420 	return 0;
421 }
422 
423 static int autofs_root_mkdir(struct inode *dir, struct dentry *dentry, int mode)
424 {
425 	struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
426 	struct autofs_dirhash *dh = &sbi->dirhash;
427 	struct autofs_dir_ent *ent;
428 	ino_t ino;
429 
430 	lock_kernel();
431 	if ( !autofs_oz_mode(sbi) ) {
432 		unlock_kernel();
433 		return -EACCES;
434 	}
435 
436 	ent = autofs_hash_lookup(dh, &dentry->d_name);
437 	if ( ent ) {
438 		unlock_kernel();
439 		return -EEXIST;
440 	}
441 
442 	if ( sbi->next_dir_ino < AUTOFS_FIRST_DIR_INO ) {
443 		printk("autofs: Out of inode numbers -- what the heck did you do??\n");
444 		unlock_kernel();
445 		return -ENOSPC;
446 	}
447 	ino = sbi->next_dir_ino++;
448 
449 	ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
450 	if ( !ent ) {
451 		unlock_kernel();
452 		return -ENOSPC;
453 	}
454 
455 	ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
456 	if ( !ent->name ) {
457 		kfree(ent);
458 		unlock_kernel();
459 		return -ENOSPC;
460 	}
461 
462 	ent->hash = dentry->d_name.hash;
463 	memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
464 	ent->ino = ino;
465 	ent->dentry = dentry;
466 	autofs_hash_insert(dh,ent);
467 
468 	dir->i_nlink++;
469 	d_instantiate(dentry, iget(dir->i_sb,ino));
470 	unlock_kernel();
471 
472 	return 0;
473 }
474 
475 /* Get/set timeout ioctl() operation */
476 static inline int autofs_get_set_timeout(struct autofs_sb_info *sbi,
477 					 unsigned long __user *p)
478 {
479 	unsigned long ntimeout;
480 
481 	if (get_user(ntimeout, p) ||
482 	    put_user(sbi->exp_timeout / HZ, p))
483 		return -EFAULT;
484 
485 	if ( ntimeout > ULONG_MAX/HZ )
486 		sbi->exp_timeout = 0;
487 	else
488 		sbi->exp_timeout = ntimeout * HZ;
489 
490 	return 0;
491 }
492 
493 /* Return protocol version */
494 static inline int autofs_get_protover(int __user *p)
495 {
496 	return put_user(AUTOFS_PROTO_VERSION, p);
497 }
498 
499 /* Perform an expiry operation */
500 static inline int autofs_expire_run(struct super_block *sb,
501 				    struct autofs_sb_info *sbi,
502 				    struct vfsmount *mnt,
503 				    struct autofs_packet_expire __user *pkt_p)
504 {
505 	struct autofs_dir_ent *ent;
506 	struct autofs_packet_expire pkt;
507 
508 	memset(&pkt,0,sizeof pkt);
509 
510 	pkt.hdr.proto_version = AUTOFS_PROTO_VERSION;
511 	pkt.hdr.type = autofs_ptype_expire;
512 
513 	if ( !sbi->exp_timeout ||
514 	     !(ent = autofs_expire(sb,sbi,mnt)) )
515 		return -EAGAIN;
516 
517 	pkt.len = ent->len;
518 	memcpy(pkt.name, ent->name, pkt.len);
519 	pkt.name[pkt.len] = '\0';
520 
521 	if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
522 		return -EFAULT;
523 
524 	return 0;
525 }
526 
527 /*
528  * ioctl()'s on the root directory is the chief method for the daemon to
529  * generate kernel reactions
530  */
531 static int autofs_root_ioctl(struct inode *inode, struct file *filp,
532 			     unsigned int cmd, unsigned long arg)
533 {
534 	struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
535 	void __user *argp = (void __user *)arg;
536 
537 	DPRINTK(("autofs_ioctl: cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",cmd,arg,sbi,process_group(current)));
538 
539 	if ( _IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
540 	     _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT )
541 		return -ENOTTY;
542 
543 	if ( !autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
544 		return -EPERM;
545 
546 	switch(cmd) {
547 	case AUTOFS_IOC_READY:	/* Wait queue: go ahead and retry */
548 		return autofs_wait_release(sbi,(autofs_wqt_t)arg,0);
549 	case AUTOFS_IOC_FAIL:	/* Wait queue: fail with ENOENT */
550 		return autofs_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
551 	case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
552 		autofs_catatonic_mode(sbi);
553 		return 0;
554 	case AUTOFS_IOC_PROTOVER: /* Get protocol version */
555 		return autofs_get_protover(argp);
556 	case AUTOFS_IOC_SETTIMEOUT:
557 		return autofs_get_set_timeout(sbi, argp);
558 	case AUTOFS_IOC_EXPIRE:
559 		return autofs_expire_run(inode->i_sb, sbi, filp->f_vfsmnt,
560 					 argp);
561 	default:
562 		return -ENOSYS;
563 	}
564 }
565