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