linux/fs/fat/file.c
<<
>>
Prefs
   1/*
   2 *  linux/fs/fat/file.c
   3 *
   4 *  Written 1992,1993 by Werner Almesberger
   5 *
   6 *  regular file handling primitives for fat-based filesystems
   7 */
   8
   9#include <linux/capability.h>
  10#include <linux/module.h>
  11#include <linux/compat.h>
  12#include <linux/mount.h>
  13#include <linux/time.h>
  14#include <linux/buffer_head.h>
  15#include <linux/writeback.h>
  16#include <linux/backing-dev.h>
  17#include <linux/blkdev.h>
  18#include <linux/fsnotify.h>
  19#include <linux/security.h>
  20#include "fat.h"
  21
  22static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
  23{
  24        u32 attr;
  25
  26        mutex_lock(&inode->i_mutex);
  27        attr = fat_make_attrs(inode);
  28        mutex_unlock(&inode->i_mutex);
  29
  30        return put_user(attr, user_attr);
  31}
  32
  33static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
  34{
  35        struct inode *inode = file_inode(file);
  36        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
  37        int is_dir = S_ISDIR(inode->i_mode);
  38        u32 attr, oldattr;
  39        struct iattr ia;
  40        int err;
  41
  42        err = get_user(attr, user_attr);
  43        if (err)
  44                goto out;
  45
  46        err = mnt_want_write_file(file);
  47        if (err)
  48                goto out;
  49        mutex_lock(&inode->i_mutex);
  50
  51        /*
  52         * ATTR_VOLUME and ATTR_DIR cannot be changed; this also
  53         * prevents the user from turning us into a VFAT
  54         * longname entry.  Also, we obviously can't set
  55         * any of the NTFS attributes in the high 24 bits.
  56         */
  57        attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR);
  58        /* Merge in ATTR_VOLUME and ATTR_DIR */
  59        attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) |
  60                (is_dir ? ATTR_DIR : 0);
  61        oldattr = fat_make_attrs(inode);
  62
  63        /* Equivalent to a chmod() */
  64        ia.ia_valid = ATTR_MODE | ATTR_CTIME;
  65        ia.ia_ctime = current_fs_time(inode->i_sb);
  66        if (is_dir)
  67                ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO);
  68        else {
  69                ia.ia_mode = fat_make_mode(sbi, attr,
  70                        S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO));
  71        }
  72
  73        /* The root directory has no attributes */
  74        if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
  75                err = -EINVAL;
  76                goto out_unlock_inode;
  77        }
  78
  79        if (sbi->options.sys_immutable &&
  80            ((attr | oldattr) & ATTR_SYS) &&
  81            !capable(CAP_LINUX_IMMUTABLE)) {
  82                err = -EPERM;
  83                goto out_unlock_inode;
  84        }
  85
  86        /*
  87         * The security check is questionable...  We single
  88         * out the RO attribute for checking by the security
  89         * module, just because it maps to a file mode.
  90         */
  91        err = security_inode_setattr(file->f_path.dentry, &ia);
  92        if (err)
  93                goto out_unlock_inode;
  94
  95        /* This MUST be done before doing anything irreversible... */
  96        err = fat_setattr(file->f_path.dentry, &ia);
  97        if (err)
  98                goto out_unlock_inode;
  99
 100        fsnotify_change(file->f_path.dentry, ia.ia_valid);
 101        if (sbi->options.sys_immutable) {
 102                if (attr & ATTR_SYS)
 103                        inode->i_flags |= S_IMMUTABLE;
 104                else
 105                        inode->i_flags &= ~S_IMMUTABLE;
 106        }
 107
 108        fat_save_attrs(inode, attr);
 109        mark_inode_dirty(inode);
 110out_unlock_inode:
 111        mutex_unlock(&inode->i_mutex);
 112        mnt_drop_write_file(file);
 113out:
 114        return err;
 115}
 116
 117static int fat_ioctl_get_volume_id(struct inode *inode, u32 __user *user_attr)
 118{
 119        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 120        return put_user(sbi->vol_id, user_attr);
 121}
 122
 123long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 124{
 125        struct inode *inode = file_inode(filp);
 126        u32 __user *user_attr = (u32 __user *)arg;
 127
 128        switch (cmd) {
 129        case FAT_IOCTL_GET_ATTRIBUTES:
 130                return fat_ioctl_get_attributes(inode, user_attr);
 131        case FAT_IOCTL_SET_ATTRIBUTES:
 132                return fat_ioctl_set_attributes(filp, user_attr);
 133        case FAT_IOCTL_GET_VOLUME_ID:
 134                return fat_ioctl_get_volume_id(inode, user_attr);
 135        default:
 136                return -ENOTTY; /* Inappropriate ioctl for device */
 137        }
 138}
 139
 140#ifdef CONFIG_COMPAT
 141static long fat_generic_compat_ioctl(struct file *filp, unsigned int cmd,
 142                                      unsigned long arg)
 143
 144{
 145        return fat_generic_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 146}
 147#endif
 148
 149static int fat_file_release(struct inode *inode, struct file *filp)
 150{
 151        if ((filp->f_mode & FMODE_WRITE) &&
 152             MSDOS_SB(inode->i_sb)->options.flush) {
 153                fat_flush_inodes(inode->i_sb, inode, NULL);
 154                congestion_wait(BLK_RW_ASYNC, HZ/10);
 155        }
 156        return 0;
 157}
 158
 159int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 160{
 161        struct inode *inode = filp->f_mapping->host;
 162        int res, err;
 163
 164        res = generic_file_fsync(filp, start, end, datasync);
 165        err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
 166
 167        return res ? res : err;
 168}
 169
 170
 171const struct file_operations fat_file_operations = {
 172        .llseek         = generic_file_llseek,
 173        .read           = do_sync_read,
 174        .write          = do_sync_write,
 175        .aio_read       = generic_file_aio_read,
 176        .aio_write      = generic_file_aio_write,
 177        .mmap           = generic_file_mmap,
 178        .release        = fat_file_release,
 179        .unlocked_ioctl = fat_generic_ioctl,
 180#ifdef CONFIG_COMPAT
 181        .compat_ioctl   = fat_generic_compat_ioctl,
 182#endif
 183        .fsync          = fat_file_fsync,
 184        .splice_read    = generic_file_splice_read,
 185};
 186
 187static int fat_cont_expand(struct inode *inode, loff_t size)
 188{
 189        struct address_space *mapping = inode->i_mapping;
 190        loff_t start = inode->i_size, count = size - inode->i_size;
 191        int err;
 192
 193        err = generic_cont_expand_simple(inode, size);
 194        if (err)
 195                goto out;
 196
 197        inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 198        mark_inode_dirty(inode);
 199        if (IS_SYNC(inode)) {
 200                int err2;
 201
 202                /*
 203                 * Opencode syncing since we don't have a file open to use
 204                 * standard fsync path.
 205                 */
 206                err = filemap_fdatawrite_range(mapping, start,
 207                                               start + count - 1);
 208                err2 = sync_mapping_buffers(mapping);
 209                if (!err)
 210                        err = err2;
 211                err2 = write_inode_now(inode, 1);
 212                if (!err)
 213                        err = err2;
 214                if (!err) {
 215                        err =  filemap_fdatawait_range(mapping, start,
 216                                                       start + count - 1);
 217                }
 218        }
 219out:
 220        return err;
 221}
 222
 223/* Free all clusters after the skip'th cluster. */
 224static int fat_free(struct inode *inode, int skip)
 225{
 226        struct super_block *sb = inode->i_sb;
 227        int err, wait, free_start, i_start, i_logstart;
 228
 229        if (MSDOS_I(inode)->i_start == 0)
 230                return 0;
 231
 232        fat_cache_inval_inode(inode);
 233
 234        wait = IS_DIRSYNC(inode);
 235        i_start = free_start = MSDOS_I(inode)->i_start;
 236        i_logstart = MSDOS_I(inode)->i_logstart;
 237
 238        /* First, we write the new file size. */
 239        if (!skip) {
 240                MSDOS_I(inode)->i_start = 0;
 241                MSDOS_I(inode)->i_logstart = 0;
 242        }
 243        MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 244        inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 245        if (wait) {
 246                err = fat_sync_inode(inode);
 247                if (err) {
 248                        MSDOS_I(inode)->i_start = i_start;
 249                        MSDOS_I(inode)->i_logstart = i_logstart;
 250                        return err;
 251                }
 252        } else
 253                mark_inode_dirty(inode);
 254
 255        /* Write a new EOF, and get the remaining cluster chain for freeing. */
 256        if (skip) {
 257                struct fat_entry fatent;
 258                int ret, fclus, dclus;
 259
 260                ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
 261                if (ret < 0)
 262                        return ret;
 263                else if (ret == FAT_ENT_EOF)
 264                        return 0;
 265
 266                fatent_init(&fatent);
 267                ret = fat_ent_read(inode, &fatent, dclus);
 268                if (ret == FAT_ENT_EOF) {
 269                        fatent_brelse(&fatent);
 270                        return 0;
 271                } else if (ret == FAT_ENT_FREE) {
 272                        fat_fs_error(sb,
 273                                     "%s: invalid cluster chain (i_pos %lld)",
 274                                     __func__, MSDOS_I(inode)->i_pos);
 275                        ret = -EIO;
 276                } else if (ret > 0) {
 277                        err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
 278                        if (err)
 279                                ret = err;
 280                }
 281                fatent_brelse(&fatent);
 282                if (ret < 0)
 283                        return ret;
 284
 285                free_start = ret;
 286        }
 287        inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
 288
 289        /* Freeing the remained cluster chain */
 290        return fat_free_clusters(inode, free_start);
 291}
 292
 293void fat_truncate_blocks(struct inode *inode, loff_t offset)
 294{
 295        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 296        const unsigned int cluster_size = sbi->cluster_size;
 297        int nr_clusters;
 298
 299        /*
 300         * This protects against truncating a file bigger than it was then
 301         * trying to write into the hole.
 302         */
 303        if (MSDOS_I(inode)->mmu_private > offset)
 304                MSDOS_I(inode)->mmu_private = offset;
 305
 306        nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;
 307
 308        fat_free(inode, nr_clusters);
 309        fat_flush_inodes(inode->i_sb, inode, NULL);
 310}
 311
 312int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
 313{
 314        struct inode *inode = dentry->d_inode;
 315        generic_fillattr(inode, stat);
 316        stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
 317
 318        if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
 319                /* Use i_pos for ino. This is used as fileid of nfs. */
 320                stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode);
 321        }
 322        return 0;
 323}
 324EXPORT_SYMBOL_GPL(fat_getattr);
 325
 326static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
 327                             struct inode *inode, umode_t *mode_ptr)
 328{
 329        umode_t mask, perm;
 330
 331        /*
 332         * Note, the basic check is already done by a caller of
 333         * (attr->ia_mode & ~FAT_VALID_MODE)
 334         */
 335
 336        if (S_ISREG(inode->i_mode))
 337                mask = sbi->options.fs_fmask;
 338        else
 339                mask = sbi->options.fs_dmask;
 340
 341        perm = *mode_ptr & ~(S_IFMT | mask);
 342
 343        /*
 344         * Of the r and x bits, all (subject to umask) must be present. Of the
 345         * w bits, either all (subject to umask) or none must be present.
 346         *
 347         * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
 348         */
 349        if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
 350                return -EPERM;
 351        if (fat_mode_can_hold_ro(inode)) {
 352                if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
 353                        return -EPERM;
 354        } else {
 355                if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
 356                        return -EPERM;
 357        }
 358
 359        *mode_ptr &= S_IFMT | perm;
 360
 361        return 0;
 362}
 363
 364static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
 365{
 366        umode_t allow_utime = sbi->options.allow_utime;
 367
 368        if (!uid_eq(current_fsuid(), inode->i_uid)) {
 369                if (in_group_p(inode->i_gid))
 370                        allow_utime >>= 3;
 371                if (allow_utime & MAY_WRITE)
 372                        return 1;
 373        }
 374
 375        /* use a default check */
 376        return 0;
 377}
 378
 379#define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
 380/* valid file mode bits */
 381#define FAT_VALID_MODE  (S_IFREG | S_IFDIR | S_IRWXUGO)
 382
 383int fat_setattr(struct dentry *dentry, struct iattr *attr)
 384{
 385        struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 386        struct inode *inode = dentry->d_inode;
 387        unsigned int ia_valid;
 388        int error;
 389
 390        /* Check for setting the inode time. */
 391        ia_valid = attr->ia_valid;
 392        if (ia_valid & TIMES_SET_FLAGS) {
 393                if (fat_allow_set_time(sbi, inode))
 394                        attr->ia_valid &= ~TIMES_SET_FLAGS;
 395        }
 396
 397        error = inode_change_ok(inode, attr);
 398        attr->ia_valid = ia_valid;
 399        if (error) {
 400                if (sbi->options.quiet)
 401                        error = 0;
 402                goto out;
 403        }
 404
 405        /*
 406         * Expand the file. Since inode_setattr() updates ->i_size
 407         * before calling the ->truncate(), but FAT needs to fill the
 408         * hole before it. XXX: this is no longer true with new truncate
 409         * sequence.
 410         */
 411        if (attr->ia_valid & ATTR_SIZE) {
 412                inode_dio_wait(inode);
 413
 414                if (attr->ia_size > inode->i_size) {
 415                        error = fat_cont_expand(inode, attr->ia_size);
 416                        if (error || attr->ia_valid == ATTR_SIZE)
 417                                goto out;
 418                        attr->ia_valid &= ~ATTR_SIZE;
 419                }
 420        }
 421
 422        if (((attr->ia_valid & ATTR_UID) &&
 423             (!uid_eq(attr->ia_uid, sbi->options.fs_uid))) ||
 424            ((attr->ia_valid & ATTR_GID) &&
 425             (!gid_eq(attr->ia_gid, sbi->options.fs_gid))) ||
 426            ((attr->ia_valid & ATTR_MODE) &&
 427             (attr->ia_mode & ~FAT_VALID_MODE)))
 428                error = -EPERM;
 429
 430        if (error) {
 431                if (sbi->options.quiet)
 432                        error = 0;
 433                goto out;
 434        }
 435
 436        /*
 437         * We don't return -EPERM here. Yes, strange, but this is too
 438         * old behavior.
 439         */
 440        if (attr->ia_valid & ATTR_MODE) {
 441                if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
 442                        attr->ia_valid &= ~ATTR_MODE;
 443        }
 444
 445        if (attr->ia_valid & ATTR_SIZE) {
 446                down_write(&MSDOS_I(inode)->truncate_lock);
 447                truncate_setsize(inode, attr->ia_size);
 448                fat_truncate_blocks(inode, attr->ia_size);
 449                up_write(&MSDOS_I(inode)->truncate_lock);
 450        }
 451
 452        setattr_copy(inode, attr);
 453        mark_inode_dirty(inode);
 454out:
 455        return error;
 456}
 457EXPORT_SYMBOL_GPL(fat_setattr);
 458
 459const struct inode_operations fat_file_inode_operations = {
 460        .setattr        = fat_setattr,
 461        .getattr        = fat_getattr,
 462};
 463
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.