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