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