Root/fs/autofs/root.c

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/capability.h>
14#include <linux/errno.h>
15#include <linux/stat.h>
16#include <linux/slab.h>
17#include <linux/param.h>
18#include <linux/time.h>
19#include <linux/smp_lock.h>
20#include "autofs_i.h"
21
22static int autofs_root_readdir(struct file *,void *,filldir_t);
23static struct dentry *autofs_root_lookup(struct inode *,struct dentry *, struct nameidata *);
24static int autofs_root_symlink(struct inode *,struct dentry *,const char *);
25static int autofs_root_unlink(struct inode *,struct dentry *);
26static int autofs_root_rmdir(struct inode *,struct dentry *);
27static int autofs_root_mkdir(struct inode *,struct dentry *,int);
28static int autofs_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
29
30const struct file_operations autofs_root_operations = {
31    .read = generic_read_dir,
32    .readdir = autofs_root_readdir,
33    .ioctl = autofs_root_ioctl,
34};
35
36const struct inode_operations autofs_root_inode_operations = {
37        .lookup = autofs_root_lookup,
38        .unlink = autofs_root_unlink,
39        .symlink = autofs_root_symlink,
40        .mkdir = autofs_root_mkdir,
41        .rmdir = autofs_root_rmdir,
42};
43
44static int autofs_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
45{
46    struct autofs_dir_ent *ent = NULL;
47    struct autofs_dirhash *dirhash;
48    struct autofs_sb_info *sbi;
49    struct inode * inode = filp->f_path.dentry->d_inode;
50    off_t onr, nr;
51
52    lock_kernel();
53
54    sbi = autofs_sbi(inode->i_sb);
55    dirhash = &sbi->dirhash;
56    nr = filp->f_pos;
57
58    switch(nr)
59    {
60    case 0:
61        if (filldir(dirent, ".", 1, nr, inode->i_ino, DT_DIR) < 0)
62            goto out;
63        filp->f_pos = ++nr;
64        /* fall through */
65    case 1:
66        if (filldir(dirent, "..", 2, nr, inode->i_ino, DT_DIR) < 0)
67            goto out;
68        filp->f_pos = ++nr;
69        /* fall through */
70    default:
71        while (onr = nr, ent = autofs_hash_enum(dirhash,&nr,ent)) {
72            if (!ent->dentry || d_mountpoint(ent->dentry)) {
73                if (filldir(dirent,ent->name,ent->len,onr,ent->ino,DT_UNKNOWN) < 0)
74                    goto out;
75                filp->f_pos = nr;
76            }
77        }
78        break;
79    }
80
81out:
82    unlock_kernel();
83    return 0;
84}
85
86static int try_to_fill_dentry(struct dentry *dentry, struct super_block *sb, struct autofs_sb_info *sbi)
87{
88    struct inode * inode;
89    struct autofs_dir_ent *ent;
90    int status = 0;
91
92    if (!(ent = autofs_hash_lookup(&sbi->dirhash, &dentry->d_name))) {
93        do {
94            if (status && dentry->d_inode) {
95                if (status != -ENOENT)
96                    printk("autofs warning: lookup failure on positive dentry, status = %d, name = %s\n", status, dentry->d_name.name);
97                return 0; /* Try to get the kernel to invalidate this dentry */
98            }
99
100            /* Turn this into a real negative dentry? */
101            if (status == -ENOENT) {
102                dentry->d_time = jiffies + AUTOFS_NEGATIVE_TIMEOUT;
103                dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
104                return 1;
105            } else if (status) {
106                /* Return a negative dentry, but leave it "pending" */
107                return 1;
108            }
109            status = autofs_wait(sbi, &dentry->d_name);
110        } while (!(ent = autofs_hash_lookup(&sbi->dirhash, &dentry->d_name)));
111    }
112
113    /* Abuse this field as a pointer to the directory entry, used to
114       find the expire list pointers */
115    dentry->d_time = (unsigned long) ent;
116    
117    if (!dentry->d_inode) {
118        inode = autofs_iget(sb, ent->ino);
119        if (IS_ERR(inode)) {
120            /* Failed, but leave pending for next time */
121            return 1;
122        }
123        dentry->d_inode = inode;
124    }
125
126    /* If this is a directory that isn't a mount point, bitch at the
127       daemon and fix it in user space */
128    if (S_ISDIR(dentry->d_inode->i_mode) && !d_mountpoint(dentry)) {
129        return !autofs_wait(sbi, &dentry->d_name);
130    }
131
132    /* We don't update the usages for the autofs daemon itself, this
133       is necessary for recursive autofs mounts */
134    if (!autofs_oz_mode(sbi)) {
135        autofs_update_usage(&sbi->dirhash,ent);
136    }
137
138    dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
139    return 1;
140}
141
142
143/*
144 * Revalidate is called on every cache lookup. Some of those
145 * cache lookups may actually happen while the dentry is not
146 * yet completely filled in, and revalidate has to delay such
147 * lookups..
148 */
149static int autofs_revalidate(struct dentry * dentry, struct nameidata *nd)
150{
151    struct inode * dir;
152    struct autofs_sb_info *sbi;
153    struct autofs_dir_ent *ent;
154    int res;
155
156    lock_kernel();
157    dir = dentry->d_parent->d_inode;
158    sbi = autofs_sbi(dir->i_sb);
159
160    /* Pending dentry */
161    if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
162        if (autofs_oz_mode(sbi))
163            res = 1;
164        else
165            res = try_to_fill_dentry(dentry, dir->i_sb, sbi);
166        unlock_kernel();
167        return res;
168    }
169
170    /* Negative dentry.. invalidate if "old" */
171    if (!dentry->d_inode) {
172        unlock_kernel();
173        return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);
174    }
175        
176    /* Check for a non-mountpoint directory */
177    if (S_ISDIR(dentry->d_inode->i_mode) && !d_mountpoint(dentry)) {
178        if (autofs_oz_mode(sbi))
179            res = 1;
180        else
181            res = try_to_fill_dentry(dentry, dir->i_sb, sbi);
182        unlock_kernel();
183        return res;
184    }
185
186    /* Update the usage list */
187    if (!autofs_oz_mode(sbi)) {
188        ent = (struct autofs_dir_ent *) dentry->d_time;
189        if (ent)
190            autofs_update_usage(&sbi->dirhash,ent);
191    }
192    unlock_kernel();
193    return 1;
194}
195
196static const struct dentry_operations autofs_dentry_operations = {
197    .d_revalidate = autofs_revalidate,
198};
199
200static struct dentry *autofs_root_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
201{
202    struct autofs_sb_info *sbi;
203    int oz_mode;
204
205    DPRINTK(("autofs_root_lookup: name = "));
206    lock_kernel();
207    autofs_say(dentry->d_name.name,dentry->d_name.len);
208
209    if (dentry->d_name.len > NAME_MAX) {
210        unlock_kernel();
211        return ERR_PTR(-ENAMETOOLONG);/* File name too long to exist */
212    }
213
214    sbi = autofs_sbi(dir->i_sb);
215
216    oz_mode = autofs_oz_mode(sbi);
217    DPRINTK(("autofs_lookup: pid = %u, pgrp = %u, catatonic = %d, "
218                "oz_mode = %d\n", task_pid_nr(current),
219                task_pgrp_nr(current), sbi->catatonic,
220                oz_mode));
221
222    /*
223     * Mark the dentry incomplete, but add it. This is needed so
224     * that the VFS layer knows about the dentry, and we can count
225     * on catching any lookups through the revalidate.
226     *
227     * Let all the hard work be done by the revalidate function that
228     * needs to be able to do this anyway..
229     *
230     * We need to do this before we release the directory semaphore.
231     */
232    dentry->d_op = &autofs_dentry_operations;
233    dentry->d_flags |= DCACHE_AUTOFS_PENDING;
234    d_add(dentry, NULL);
235
236    mutex_unlock(&dir->i_mutex);
237    autofs_revalidate(dentry, nd);
238    mutex_lock(&dir->i_mutex);
239
240    /*
241     * If we are still pending, check if we had to handle
242     * a signal. If so we can force a restart..
243     */
244    if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
245        /* See if we were interrupted */
246        if (signal_pending(current)) {
247            sigset_t *sigset = &current->pending.signal;
248            if (sigismember (sigset, SIGKILL) ||
249                sigismember (sigset, SIGQUIT) ||
250                sigismember (sigset, SIGINT)) {
251                unlock_kernel();
252                return ERR_PTR(-ERESTARTNOINTR);
253            }
254        }
255    }
256    unlock_kernel();
257
258    /*
259     * If this dentry is unhashed, then we shouldn't honour this
260     * lookup even if the dentry is positive. Returning ENOENT here
261     * doesn't do the right thing for all system calls, but it should
262     * be OK for the operations we permit from an autofs.
263     */
264    if (dentry->d_inode && d_unhashed(dentry))
265        return ERR_PTR(-ENOENT);
266
267    return NULL;
268}
269
270static int autofs_root_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
271{
272    struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
273    struct autofs_dirhash *dh = &sbi->dirhash;
274    struct autofs_dir_ent *ent;
275    unsigned int n;
276    int slsize;
277    struct autofs_symlink *sl;
278    struct inode *inode;
279
280    DPRINTK(("autofs_root_symlink: %s <- ", symname));
281    autofs_say(dentry->d_name.name,dentry->d_name.len);
282
283    lock_kernel();
284    if (!autofs_oz_mode(sbi)) {
285        unlock_kernel();
286        return -EACCES;
287    }
288
289    if (autofs_hash_lookup(dh, &dentry->d_name)) {
290        unlock_kernel();
291        return -EEXIST;
292    }
293
294    n = find_first_zero_bit(sbi->symlink_bitmap,AUTOFS_MAX_SYMLINKS);
295    if (n >= AUTOFS_MAX_SYMLINKS) {
296        unlock_kernel();
297        return -ENOSPC;
298    }
299
300    set_bit(n,sbi->symlink_bitmap);
301    sl = &sbi->symlink[n];
302    sl->len = strlen(symname);
303    sl->data = kmalloc(slsize = sl->len+1, GFP_KERNEL);
304    if (!sl->data) {
305        clear_bit(n,sbi->symlink_bitmap);
306        unlock_kernel();
307        return -ENOSPC;
308    }
309
310    ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
311    if (!ent) {
312        kfree(sl->data);
313        clear_bit(n,sbi->symlink_bitmap);
314        unlock_kernel();
315        return -ENOSPC;
316    }
317
318    ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
319    if (!ent->name) {
320        kfree(sl->data);
321        kfree(ent);
322        clear_bit(n,sbi->symlink_bitmap);
323        unlock_kernel();
324        return -ENOSPC;
325    }
326
327    memcpy(sl->data,symname,slsize);
328    sl->mtime = get_seconds();
329
330    ent->ino = AUTOFS_FIRST_SYMLINK + n;
331    ent->hash = dentry->d_name.hash;
332    memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
333    ent->dentry = NULL; /* We don't keep the dentry for symlinks */
334
335    autofs_hash_insert(dh,ent);
336
337    inode = autofs_iget(dir->i_sb, ent->ino);
338    if (IS_ERR(inode))
339        return PTR_ERR(inode);
340
341    d_instantiate(dentry, inode);
342    unlock_kernel();
343    return 0;
344}
345
346/*
347 * NOTE!
348 *
349 * Normal filesystems would do a "d_delete()" to tell the VFS dcache
350 * that the file no longer exists. However, doing that means that the
351 * VFS layer can turn the dentry into a negative dentry, which we
352 * obviously do not want (we're dropping the entry not because it
353 * doesn't exist, but because it has timed out).
354 *
355 * Also see autofs_root_rmdir()..
356 */
357static int autofs_root_unlink(struct inode *dir, struct dentry *dentry)
358{
359    struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
360    struct autofs_dirhash *dh = &sbi->dirhash;
361    struct autofs_dir_ent *ent;
362    unsigned int n;
363
364    /* This allows root to remove symlinks */
365    lock_kernel();
366    if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN)) {
367        unlock_kernel();
368        return -EACCES;
369    }
370
371    ent = autofs_hash_lookup(dh, &dentry->d_name);
372    if (!ent) {
373        unlock_kernel();
374        return -ENOENT;
375    }
376
377    n = ent->ino - AUTOFS_FIRST_SYMLINK;
378    if (n >= AUTOFS_MAX_SYMLINKS) {
379        unlock_kernel();
380        return -EISDIR; /* It's a directory, dummy */
381    }
382    if (!test_bit(n,sbi->symlink_bitmap)) {
383        unlock_kernel();
384        return -EINVAL; /* Nonexistent symlink? Shouldn't happen */
385    }
386    
387    dentry->d_time = (unsigned long)(struct autofs_dirhash *)NULL;
388    autofs_hash_delete(ent);
389    clear_bit(n,sbi->symlink_bitmap);
390    kfree(sbi->symlink[n].data);
391    d_drop(dentry);
392    
393    unlock_kernel();
394    return 0;
395}
396
397static int autofs_root_rmdir(struct inode *dir, struct dentry *dentry)
398{
399    struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
400    struct autofs_dirhash *dh = &sbi->dirhash;
401    struct autofs_dir_ent *ent;
402
403    lock_kernel();
404    if (!autofs_oz_mode(sbi)) {
405        unlock_kernel();
406        return -EACCES;
407    }
408
409    ent = autofs_hash_lookup(dh, &dentry->d_name);
410    if (!ent) {
411        unlock_kernel();
412        return -ENOENT;
413    }
414
415    if ((unsigned int)ent->ino < AUTOFS_FIRST_DIR_INO) {
416        unlock_kernel();
417        return -ENOTDIR; /* Not a directory */
418    }
419
420    if (ent->dentry != dentry) {
421        printk("autofs_rmdir: odentry != dentry for entry %s\n", dentry->d_name.name);
422    }
423
424    dentry->d_time = (unsigned long)(struct autofs_dir_ent *)NULL;
425    autofs_hash_delete(ent);
426    drop_nlink(dir);
427    d_drop(dentry);
428    unlock_kernel();
429
430    return 0;
431}
432
433static int autofs_root_mkdir(struct inode *dir, struct dentry *dentry, int mode)
434{
435    struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
436    struct autofs_dirhash *dh = &sbi->dirhash;
437    struct autofs_dir_ent *ent;
438    struct inode *inode;
439    ino_t ino;
440
441    lock_kernel();
442    if (!autofs_oz_mode(sbi)) {
443        unlock_kernel();
444        return -EACCES;
445    }
446
447    ent = autofs_hash_lookup(dh, &dentry->d_name);
448    if (ent) {
449        unlock_kernel();
450        return -EEXIST;
451    }
452
453    if (sbi->next_dir_ino < AUTOFS_FIRST_DIR_INO) {
454        printk("autofs: Out of inode numbers -- what the heck did you do??\n");
455        unlock_kernel();
456        return -ENOSPC;
457    }
458    ino = sbi->next_dir_ino++;
459
460    ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
461    if (!ent) {
462        unlock_kernel();
463        return -ENOSPC;
464    }
465
466    ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
467    if (!ent->name) {
468        kfree(ent);
469        unlock_kernel();
470        return -ENOSPC;
471    }
472
473    ent->hash = dentry->d_name.hash;
474    memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
475    ent->ino = ino;
476    ent->dentry = dentry;
477    autofs_hash_insert(dh,ent);
478
479    inc_nlink(dir);
480
481    inode = autofs_iget(dir->i_sb, ino);
482    if (IS_ERR(inode)) {
483        drop_nlink(dir);
484        return PTR_ERR(inode);
485    }
486
487    d_instantiate(dentry, inode);
488    unlock_kernel();
489
490    return 0;
491}
492
493/* Get/set timeout ioctl() operation */
494static inline int autofs_get_set_timeout(struct autofs_sb_info *sbi,
495                     unsigned long __user *p)
496{
497    unsigned long ntimeout;
498
499    if (get_user(ntimeout, p) ||
500        put_user(sbi->exp_timeout / HZ, p))
501        return -EFAULT;
502
503    if (ntimeout > ULONG_MAX/HZ)
504        sbi->exp_timeout = 0;
505    else
506        sbi->exp_timeout = ntimeout * HZ;
507
508    return 0;
509}
510
511/* Return protocol version */
512static inline int autofs_get_protover(int __user *p)
513{
514    return put_user(AUTOFS_PROTO_VERSION, p);
515}
516
517/* Perform an expiry operation */
518static inline int autofs_expire_run(struct super_block *sb,
519                    struct autofs_sb_info *sbi,
520                    struct vfsmount *mnt,
521                    struct autofs_packet_expire __user *pkt_p)
522{
523    struct autofs_dir_ent *ent;
524    struct autofs_packet_expire pkt;
525
526    memset(&pkt,0,sizeof pkt);
527
528    pkt.hdr.proto_version = AUTOFS_PROTO_VERSION;
529    pkt.hdr.type = autofs_ptype_expire;
530
531    if (!sbi->exp_timeout || !(ent = autofs_expire(sb,sbi,mnt)))
532        return -EAGAIN;
533
534    pkt.len = ent->len;
535    memcpy(pkt.name, ent->name, pkt.len);
536    pkt.name[pkt.len] = '\0';
537
538    if (copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)))
539        return -EFAULT;
540
541    return 0;
542}
543
544/*
545 * ioctl()'s on the root directory is the chief method for the daemon to
546 * generate kernel reactions
547 */
548static int autofs_root_ioctl(struct inode *inode, struct file *filp,
549                 unsigned int cmd, unsigned long arg)
550{
551    struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
552    void __user *argp = (void __user *)arg;
553
554    DPRINTK(("autofs_ioctl: cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",cmd,arg,sbi,task_pgrp_nr(current)));
555
556    if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
557         _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
558        return -ENOTTY;
559    
560    if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
561        return -EPERM;
562    
563    switch(cmd) {
564    case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */
565        return autofs_wait_release(sbi,(autofs_wqt_t)arg,0);
566    case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */
567        return autofs_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
568    case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
569        autofs_catatonic_mode(sbi);
570        return 0;
571    case AUTOFS_IOC_PROTOVER: /* Get protocol version */
572        return autofs_get_protover(argp);
573    case AUTOFS_IOC_SETTIMEOUT:
574        return autofs_get_set_timeout(sbi, argp);
575    case AUTOFS_IOC_EXPIRE:
576        return autofs_expire_run(inode->i_sb, sbi, filp->f_path.mnt,
577                     argp);
578    default:
579        return -ENOSYS;
580    }
581}
582

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