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        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
 117long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 118{
 119        struct inode *inode = filp->f_path.dentry->d_inode;
 120        u32 __user *user_attr = (u32 __user *)arg;
 121
 122        switch (cmd) {
 123        case FAT_IOCTL_GET_ATTRIBUTES:
 124                return fat_ioctl_get_attributes(inode, user_attr);
 125        case FAT_IOCTL_SET_ATTRIBUTES:
 126                return fat_ioctl_set_attributes(filp, user_attr);
 127        default:
 128                return -ENOTTY; /* Inappropriate ioctl for device */
 129        }
 130}
 131
 132#ifdef CONFIG_COMPAT
 133static long fat_generic_compat_ioctl(struct file *filp, unsigned int cmd,
 134                                      unsigned long arg)
 135
 136{
 137        return fat_generic_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 138}
 139#endif
 140
 141static int fat_file_release(struct inode *inode, struct file *filp)
 142{
 143        if ((filp->f_mode & FMODE_WRITE) &&
 144             MSDOS_SB(inode->i_sb)->options.flush) {
 145                fat_flush_inodes(inode->i_sb, inode, NULL);
 146                congestion_wait(BLK_RW_ASYNC, HZ/10);
 147        }
 148        return 0;
 149}
 150
 151int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 152{
 153        struct inode *inode = filp->f_mapping->host;
 154        int res, err;
 155
 156        res = generic_file_fsync(filp, start, end, datasync);
 157        err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
 158
 159        return res ? res : err;
 160}
 161
 162
 163const struct file_operations fat_file_operations = {
 164        .llseek         = generic_file_llseek,
 165        .read           = do_sync_read,
 166        .write          = do_sync_write,
 167        .aio_read       = generic_file_aio_read,
 168        .aio_write      = generic_file_aio_write,
 169        .mmap           = generic_file_mmap,
 170        .release        = fat_file_release,
 171        .unlocked_ioctl = fat_generic_ioctl,
 172#ifdef CONFIG_COMPAT
 173        .compat_ioctl   = fat_generic_compat_ioctl,
 174#endif
 175        .fsync          = fat_file_fsync,
 176        .splice_read    = generic_file_splice_read,
 177};
 178
 179static int fat_cont_expand(struct inode *inode, loff_t size)
 180{
 181        struct address_space *mapping = inode->i_mapping;
 182        loff_t start = inode->i_size, count = size - inode->i_size;
 183        int err;
 184
 185        err = generic_cont_expand_simple(inode, size);
 186        if (err)
 187                goto out;
 188
 189        inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 190        mark_inode_dirty(inode);
 191        if (IS_SYNC(inode)) {
 192                int err2;
 193
 194                /*
 195                 * Opencode syncing since we don't have a file open to use
 196                 * standard fsync path.
 197                 */
 198                err = filemap_fdatawrite_range(mapping, start,
 199                                               start + count - 1);
 200                err2 = sync_mapping_buffers(mapping);
 201                if (!err)
 202                        err = err2;
 203                err2 = write_inode_now(inode, 1);
 204                if (!err)
 205                        err = err2;
 206                if (!err) {
 207                        err =  filemap_fdatawait_range(mapping, start,
 208                                                       start + count - 1);
 209                }
 210        }
 211out:
 212        return err;
 213}
 214
 215/* Free all clusters after the skip'th cluster. */
 216static int fat_free(struct inode *inode, int skip)
 217{
 218        struct super_block *sb = inode->i_sb;
 219        int err, wait, free_start, i_start, i_logstart;
 220
 221        if (MSDOS_I(inode)->i_start == 0)
 222                return 0;
 223
 224        fat_cache_inval_inode(inode);
 225
 226        wait = IS_DIRSYNC(inode);
 227        i_start = free_start = MSDOS_I(inode)->i_start;
 228        i_logstart = MSDOS_I(inode)->i_logstart;
 229
 230        /* First, we write the new file size. */
 231        if (!skip) {
 232                MSDOS_I(inode)->i_start = 0;
 233                MSDOS_I(inode)->i_logstart = 0;
 234        }
 235        MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 236        inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 237        if (wait) {
 238                err = fat_sync_inode(inode);
 239                if (err) {
 240                        MSDOS_I(inode)->i_start = i_start;
 241                        MSDOS_I(inode)->i_logstart = i_logstart;
 242                        return err;
 243                }
 244        } else
 245                mark_inode_dirty(inode);
 246
 247        /* Write a new EOF, and get the remaining cluster chain for freeing. */
 248        if (skip) {
 249                struct fat_entry fatent;
 250                int ret, fclus, dclus;
 251
 252                ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
 253                if (ret < 0)
 254                        return ret;
 255                else if (ret == FAT_ENT_EOF)
 256                        return 0;
 257
 258                fatent_init(&fatent);
 259                ret = fat_ent_read(inode, &fatent, dclus);
 260                if (ret == FAT_ENT_EOF) {
 261                        fatent_brelse(&fatent);
 262                        return 0;
 263                } else if (ret == FAT_ENT_FREE) {
 264                        fat_fs_error(sb,
 265                                     "%s: invalid cluster chain (i_pos %lld)",
 266                                     __func__, MSDOS_I(inode)->i_pos);
 267                        ret = -EIO;
 268                } else if (ret > 0) {
 269                        err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
 270                        if (err)
 271                                ret = err;
 272                }
 273                fatent_brelse(&fatent);
 274                if (ret < 0)
 275                        return ret;
 276
 277                free_start = ret;
 278        }
 279        inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
 280
 281        /* Freeing the remained cluster chain */
 282        return fat_free_clusters(inode, free_start);
 283}
 284
 285void fat_truncate_blocks(struct inode *inode, loff_t offset)
 286{
 287        struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 288        const unsigned int cluster_size = sbi->cluster_size;
 289        int nr_clusters;
 290
 291        /*
 292         * This protects against truncating a file bigger than it was then
 293         * trying to write into the hole.
 294         */
 295        if (MSDOS_I(inode)->mmu_private > offset)
 296                MSDOS_I(inode)->mmu_private = offset;
 297
 298        nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;
 299
 300        fat_free(inode, nr_clusters);
 301        fat_flush_inodes(inode->i_sb, inode, NULL);
 302}
 303
 304int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
 305{
 306        struct inode *inode = dentry->d_inode;
 307        generic_fillattr(inode, stat);
 308        stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
 309        return 0;
 310}
 311EXPORT_SYMBOL_GPL(fat_getattr);
 312
 313static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
 314                             struct inode *inode, umode_t *mode_ptr)
 315{
 316        umode_t mask, perm;
 317
 318        /*
 319         * Note, the basic check is already done by a caller of
 320         * (attr->ia_mode & ~FAT_VALID_MODE)
 321         */
 322
 323        if (S_ISREG(inode->i_mode))
 324                mask = sbi->options.fs_fmask;
 325        else
 326                mask = sbi->options.fs_dmask;
 327
 328        perm = *mode_ptr & ~(S_IFMT | mask);
 329
 330        /*
 331         * Of the r and x bits, all (subject to umask) must be present. Of the
 332         * w bits, either all (subject to umask) or none must be present.
 333         *
 334         * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
 335         */
 336        if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
 337                return -EPERM;
 338        if (fat_mode_can_hold_ro(inode)) {
 339                if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
 340                        return -EPERM;
 341        } else {
 342                if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
 343                        return -EPERM;
 344        }
 345
 346        *mode_ptr &= S_IFMT | perm;
 347
 348        return 0;
 349}
 350
 351static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
 352{
 353        umode_t allow_utime = sbi->options.allow_utime;
 354
 355        if (!uid_eq(current_fsuid(), inode->i_uid)) {
 356                if (in_group_p(inode->i_gid))
 357                        allow_utime >>= 3;
 358                if (allow_utime & MAY_WRITE)
 359                        return 1;
 360        }
 361
 362        /* use a default check */
 363        return 0;
 364}
 365
 366#define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
 367/* valid file mode bits */
 368#define FAT_VALID_MODE  (S_IFREG | S_IFDIR | S_IRWXUGO)
 369
 370int fat_setattr(struct dentry *dentry, struct iattr *attr)
 371{
 372        struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 373        struct inode *inode = dentry->d_inode;
 374        unsigned int ia_valid;
 375        int error;
 376
 377        /* Check for setting the inode time. */
 378        ia_valid = attr->ia_valid;
 379        if (ia_valid & TIMES_SET_FLAGS) {
 380                if (fat_allow_set_time(sbi, inode))
 381                        attr->ia_valid &= ~TIMES_SET_FLAGS;
 382        }
 383
 384        error = inode_change_ok(inode, attr);
 385        attr->ia_valid = ia_valid;
 386        if (error) {
 387                if (sbi->options.quiet)
 388                        error = 0;
 389                goto out;
 390        }
 391
 392        /*
 393         * Expand the file. Since inode_setattr() updates ->i_size
 394         * before calling the ->truncate(), but FAT needs to fill the
 395         * hole before it. XXX: this is no longer true with new truncate
 396         * sequence.
 397         */
 398        if (attr->ia_valid & ATTR_SIZE) {
 399                inode_dio_wait(inode);
 400
 401                if (attr->ia_size > inode->i_size) {
 402                        error = fat_cont_expand(inode, attr->ia_size);
 403                        if (error || attr->ia_valid == ATTR_SIZE)
 404                                goto out;
 405                        attr->ia_valid &= ~ATTR_SIZE;
 406                }
 407        }
 408
 409        if (((attr->ia_valid & ATTR_UID) &&
 410             (!uid_eq(attr->ia_uid, sbi->options.fs_uid))) ||
 411            ((attr->ia_valid & ATTR_GID) &&
 412             (!gid_eq(attr->ia_gid, sbi->options.fs_gid))) ||
 413            ((attr->ia_valid & ATTR_MODE) &&
 414             (attr->ia_mode & ~FAT_VALID_MODE)))
 415                error = -EPERM;
 416
 417        if (error) {
 418                if (sbi->options.quiet)
 419                        error = 0;
 420                goto out;
 421        }
 422
 423        /*
 424         * We don't return -EPERM here. Yes, strange, but this is too
 425         * old behavior.
 426         */
 427        if (attr->ia_valid & ATTR_MODE) {
 428                if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
 429                        attr->ia_valid &= ~ATTR_MODE;
 430        }
 431
 432        if (attr->ia_valid & ATTR_SIZE) {
 433                down_write(&MSDOS_I(inode)->truncate_lock);
 434                truncate_setsize(inode, attr->ia_size);
 435                fat_truncate_blocks(inode, attr->ia_size);
 436                up_write(&MSDOS_I(inode)->truncate_lock);
 437        }
 438
 439        setattr_copy(inode, attr);
 440        mark_inode_dirty(inode);
 441out:
 442        return error;
 443}
 444EXPORT_SYMBOL_GPL(fat_setattr);
 445
 446const struct inode_operations fat_file_inode_operations = {
 447        .setattr        = fat_setattr,
 448        .getattr        = fat_getattr,
 449};
 450
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