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
367#define TIMES_SET_FLAGS	(ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
368/* valid file mode bits */
369#define FAT_VALID_MODE	(S_IFREG | S_IFDIR | S_IRWXUGO)
370
371int fat_setattr(struct dentry *dentry, struct iattr *attr)
372{
373	struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
374	struct inode *inode = dentry->d_inode;
375	unsigned int ia_valid;
376	int error;
377
378	/* Check for setting the inode time. */
379	ia_valid = attr->ia_valid;
380	if (ia_valid & TIMES_SET_FLAGS) {
381		if (fat_allow_set_time(sbi, inode))
382			attr->ia_valid &= ~TIMES_SET_FLAGS;
383	}
384
385	error = inode_change_ok(inode, attr);
386	attr->ia_valid = ia_valid;
387	if (error) {
388		if (sbi->options.quiet)
389			error = 0;
390		goto out;
391	}
392
393	if (attr->ia_valid & ATTR_SIZE) {
394		if (attr->ia_size > inode->i_size) {
395			error = fat_cont_expand(inode, attr->ia_size);
396			if (error || attr->ia_valid == ATTR_SIZE)
397				goto out;
398			attr->ia_valid &= ~ATTR_SIZE;
399		}
400	}
401
402	if (((attr->ia_valid & ATTR_UID) &&
403	     (attr->ia_uid != sbi->options.fs_uid)) ||
404	    ((attr->ia_valid & ATTR_GID) &&
405	     (attr->ia_gid != sbi->options.fs_gid)) ||
406	    ((attr->ia_valid & ATTR_MODE) &&
407	     (attr->ia_mode & ~FAT_VALID_MODE)))
408		error = -EPERM;
409
410	if (error) {
411		if (sbi->options.quiet)
412			error = 0;
413		goto out;
414	}
415
416	/*
417	 * We don't return -EPERM here. Yes, strange, but this is too
418	 * old behavior.
419	 */
420	if (attr->ia_valid & ATTR_MODE) {
421		if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
422			attr->ia_valid &= ~ATTR_MODE;
423	}
424
425	if (attr->ia_valid & ATTR_SIZE) {
426		truncate_setsize(inode, attr->ia_size);
427		fat_truncate_blocks(inode, attr->ia_size);
428	}
429
430	setattr_copy(inode, attr);
431	mark_inode_dirty(inode);
432out:
433	return error;
434}
435EXPORT_SYMBOL_GPL(fat_setattr);
436
437const struct inode_operations fat_file_inode_operations = {
438	.setattr	= fat_setattr,
439	.getattr	= fat_getattr,
440};
441