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TOMOYO Linux Cross Reference
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 
 22 static 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 
 33 static 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);
110 out_unlock_inode:
111         mutex_unlock(&inode->i_mutex);
112         mnt_drop_write_file(file);
113 out:
114         return err;
115 }
116 
117 long 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
133 static 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 
141 static 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 
151 int 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 
163 const 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 
179 static 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         }
211 out:
212         return err;
213 }
214 
215 /* Free all clusters after the skip'th cluster. */
216 static 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 
285 void 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 
304 int 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 }
311 EXPORT_SYMBOL_GPL(fat_getattr);
312 
313 static 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 
351 static 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 
370 int 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);
441 out:
442         return error;
443 }
444 EXPORT_SYMBOL_GPL(fat_setattr);
445 
446 const struct inode_operations fat_file_inode_operations = {
447         .setattr        = fat_setattr,
448         .getattr        = fat_getattr,
449 };
450 

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