linux/fs/fat/file.c
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   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->f_path.dentry->d_inode;
  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        mutex_lock(&inode->i_mutex);
  47        err = mnt_want_write(file->f_path.mnt);
  48        if (err)
  49                goto out_unlock_inode;
  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_drop_write;
  77        }
  78
  79        if (sbi->options.sys_immutable &&
  80            ((attr | oldattr) & ATTR_SYS) &&
  81            !capable(CAP_LINUX_IMMUTABLE)) {
  82                err = -EPERM;
  83                goto out_drop_write;
  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_drop_write;
  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_drop_write;
  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_drop_write:
 111        mnt_drop_write(file->f_path.mnt);
 112out_unlock_inode:
 113        mutex_unlock(&inode->i_mutex);
 114out:
 115        return err;
 116}
 117
 118long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 119{
 120        struct inode *inode = filp->f_path.dentry->d_inode;
 121        u32 __user *user_attr = (u32 __user *)arg;
 122
 123        switch (cmd) {
 124        case FAT_IOCTL_GET_ATTRIBUTES:
 125                return fat_ioctl_get_attributes(inode, user_attr);
 126        case FAT_IOCTL_SET_ATTRIBUTES:
 127                return fat_ioctl_set_attributes(filp, user_attr);
 128        default:
 129                return -ENOTTY; /* Inappropriate ioctl for device */
 130        }
 131}
 132
 133#ifdef CONFIG_COMPAT
 134static long fat_generic_compat_ioctl(struct file *filp, unsigned int cmd,
 135                                      unsigned long arg)
 136
 137{
 138        return fat_generic_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 139}
 140#endif
 141
 142static int fat_file_release(struct inode *inode, struct file *filp)
 143{
 144        if ((filp->f_mode & FMODE_WRITE) &&
 145             MSDOS_SB(inode->i_sb)->options.flush) {
 146                fat_flush_inodes(inode->i_sb, inode, NULL);
 147                congestion_wait(BLK_RW_ASYNC, HZ/10);
 148        }
 149        return 0;
 150}
 151
 152int fat_file_fsync(struct file *filp, int datasync)
 153{
 154        struct inode *inode = filp->f_mapping->host;
 155        int res, err;
 156
 157        res = generic_file_fsync(filp, datasync);
 158        err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
 159
 160        return res ? res : err;
 161}
 162
 163
 164const struct file_operations fat_file_operations = {
 165        .llseek         = generic_file_llseek,
 166        .read           = do_sync_read,
 167        .write          = do_sync_write,
 168        .aio_read       = generic_file_aio_read,
 169        .aio_write      = generic_file_aio_write,
 170        .mmap           = generic_file_mmap,
 171        .release        = fat_file_release,
 172        .unlocked_ioctl = fat_generic_ioctl,
 173#ifdef CONFIG_COMPAT
 174        .compat_ioctl   = fat_generic_compat_ioctl,
 175#endif
 176        .fsync          = fat_file_fsync,
 177        .splice_read    = generic_file_splice_read,
 178};
 179
 180static int fat_cont_expand(struct inode *inode, loff_t size)
 181{
 182        struct address_space *mapping = inode->i_mapping;
 183        loff_t start = inode->i_size, count = size - inode->i_size;
 184        int err;
 185
 186        err = generic_cont_expand_simple(inode, size);
 187        if (err)
 188                goto out;
 189
 190        inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 191        mark_inode_dirty(inode);
 192        if (IS_SYNC(inode)) {
 193                int err2;
 194
 195                /*
 196                 * Opencode syncing since we don't have a file open to use
 197                 * standard fsync path.
 198                 */
 199                err = filemap_fdatawrite_range(mapping, start,
 200                                               start + count - 1);
 201                err2 = sync_mapping_buffers(mapping);
 202                if (!err)
 203                        err = err2;
 204                err2 = write_inode_now(inode, 1);
 205                if (!err)
 206                        err = err2;
 207                if (!err) {
 208                        err =  filemap_fdatawait_range(mapping, start,
 209                                                       start + count - 1);
 210                }
 211        }
 212out:
 213        return err;
 214}
 215
 216/* Free all clusters after the skip'th cluster. */
 217static int fat_free(struct inode *inode, int skip)
 218{
 219        struct super_block *sb = inode->i_sb;
 220        int err, wait, free_start, i_start, i_logstart;
 221
 222        if (MSDOS_I(inode)->i_start == 0)
 223                return 0;
 224
 225        fat_cache_inval_inode(inode);
 226
 227        wait = IS_DIRSYNC(inode);
 228        i_start = free_start = MSDOS_I(inode)->i_start;
 229        i_logstart = MSDOS_I(inode)->i_logstart;
 230
 231        /* First, we write the new file size. */
 232        if (!skip) {
 233                MSDOS_I(inode)->i_start = 0;
 234                MSDOS_I(inode)->i_logstart = 0;
 235        }
 236        MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 237        inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 238        if (wait) {
 239                err = fat_sync_inode(inode);
 240                if (err) {
 241                        MSDOS_I(inode)->i_start = i_start;
 242                        MSDOS_I(inode)->i_logstart = i_logstart;
 243                        return err;
 244                }
 245        } else
 246                mark_inode_dirty(inode);
 247
 248        /* Write a new EOF, and get the remaining cluster chain for freeing. */
 249        if (skip) {
 250                struct fat_entry fatent;
 251                int ret, fclus, dclus;
 252
 253                ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
 254                if (ret < 0)
 255                        return ret;
 256                else if (ret == FAT_ENT_EOF)
 257                        return 0;
 258
 259                fatent_init(&fatent);
 260                ret = fat_ent_read(inode, &fatent, dclus);
 261                if (ret == FAT_ENT_EOF) {
 262                        fatent_brelse(&fatent);
 263                        return 0;
 264                } else if (ret == FAT_ENT_FREE) {
 265                        fat_fs_error(sb,
 266                                     "%s: invalid cluster chain (i_pos %lld)",
 267                                     __func__, MSDOS_I(inode)->i_pos);
 268                        ret = -EIO;
 269                } else if (ret > 0) {
 270                        err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
 271                        if (err)
 272                                ret = err;
 273                }
 274                fatent_brelse(&fatent);
 275                if (ret < 0)
 276                        return ret;
 277
 278                free_start = ret;
 279        }
 280        inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
 281
 282        /* Freeing the remained cluster chain */
 283        return fat_free_clusters(inode, free_start);
 284}
 285
 286void fat_truncate_blocks(struct inode *inode, loff_t offset)
 287{
 288        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 289        const unsigned int cluster_size = sbi->cluster_size;
 290        int nr_clusters;
 291
 292        /*
 293         * This protects against truncating a file bigger than it was then
 294         * trying to write into the hole.
 295         */
 296        if (MSDOS_I(inode)->mmu_private > offset)
 297                MSDOS_I(inode)->mmu_private = offset;
 298
 299        nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;
 300
 301        fat_free(inode, nr_clusters);
 302        fat_flush_inodes(inode->i_sb, inode, NULL);
 303}
 304
 305int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
 306{
 307        struct inode *inode = dentry->d_inode;
 308        generic_fillattr(inode, stat);
 309        stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
 310        return 0;
 311}
 312EXPORT_SYMBOL_GPL(fat_getattr);
 313
 314static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
 315                             struct inode *inode, umode_t *mode_ptr)
 316{
 317        mode_t mask, perm;
 318
 319        /*
 320         * Note, the basic check is already done by a caller of
 321         * (attr->ia_mode & ~FAT_VALID_MODE)
 322         */
 323
 324        if (S_ISREG(inode->i_mode))
 325                mask = sbi->options.fs_fmask;
 326        else
 327                mask = sbi->options.fs_dmask;
 328
 329        perm = *mode_ptr & ~(S_IFMT | mask);
 330
 331        /*
 332         * Of the r and x bits, all (subject to umask) must be present. Of the
 333         * w bits, either all (subject to umask) or none must be present.
 334         *
 335         * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
 336         */
 337        if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
 338                return -EPERM;
 339        if (fat_mode_can_hold_ro(inode)) {
 340                if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
 341                        return -EPERM;
 342        } else {
 343                if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
 344                        return -EPERM;
 345        }
 346
 347        *mode_ptr &= S_IFMT | perm;
 348
 349        return 0;
 350}
 351
 352static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
 353{
 354        mode_t allow_utime = sbi->options.allow_utime;
 355
 356        if (current_fsuid() != inode->i_uid) {
 357                if (in_group_p(inode->i_gid))
 358                        allow_utime >>= 3;
 359                if (allow_utime & MAY_WRITE)
 360                        return 1;
 361        }
 362
 363        /* use a default check */
 364        return 0;
 365}
 366
 367int fat_setsize(struct inode *inode, loff_t offset)
 368{
 369        int error;
 370
 371        error = simple_setsize(inode, offset);
 372        if (error)
 373                return error;
 374        fat_truncate_blocks(inode, offset);
 375
 376        return error;
 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        /*
 391         * Expand the file. Since inode_setattr() updates ->i_size
 392         * before calling the ->truncate(), but FAT needs to fill the
 393         * hole before it. XXX: this is no longer true with new truncate
 394         * sequence.
 395         */
 396        if (attr->ia_valid & ATTR_SIZE) {
 397                if (attr->ia_size > inode->i_size) {
 398                        error = fat_cont_expand(inode, attr->ia_size);
 399                        if (error || attr->ia_valid == ATTR_SIZE)
 400                                goto out;
 401                        attr->ia_valid &= ~ATTR_SIZE;
 402                }
 403        }
 404
 405        /* Check for setting the inode time. */
 406        ia_valid = attr->ia_valid;
 407        if (ia_valid & TIMES_SET_FLAGS) {
 408                if (fat_allow_set_time(sbi, inode))
 409                        attr->ia_valid &= ~TIMES_SET_FLAGS;
 410        }
 411
 412        error = inode_change_ok(inode, attr);
 413        attr->ia_valid = ia_valid;
 414        if (error) {
 415                if (sbi->options.quiet)
 416                        error = 0;
 417                goto out;
 418        }
 419
 420        if (((attr->ia_valid & ATTR_UID) &&
 421             (attr->ia_uid != sbi->options.fs_uid)) ||
 422            ((attr->ia_valid & ATTR_GID) &&
 423             (attr->ia_gid != sbi->options.fs_gid)) ||
 424            ((attr->ia_valid & ATTR_MODE) &&
 425             (attr->ia_mode & ~FAT_VALID_MODE)))
 426                error = -EPERM;
 427
 428        if (error) {
 429                if (sbi->options.quiet)
 430                        error = 0;
 431                goto out;
 432        }
 433
 434        /*
 435         * We don't return -EPERM here. Yes, strange, but this is too
 436         * old behavior.
 437         */
 438        if (attr->ia_valid & ATTR_MODE) {
 439                if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
 440                        attr->ia_valid &= ~ATTR_MODE;
 441        }
 442
 443        if (attr->ia_valid & ATTR_SIZE) {
 444                error = fat_setsize(inode, attr->ia_size);
 445                if (error)
 446                        goto out;
 447        }
 448
 449        generic_setattr(inode, attr);
 450        mark_inode_dirty(inode);
 451out:
 452        return error;
 453}
 454EXPORT_SYMBOL_GPL(fat_setattr);
 455
 456const struct inode_operations fat_file_inode_operations = {
 457        .setattr        = fat_setattr,
 458        .getattr        = fat_getattr,
 459};
 460
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