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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * linux/fs/fat/file.c4 *5 * Written 1992,1993 by Werner Almesberger6 *7 * regular file handling primitives for fat-based filesystems8 */9 10#include <linux/capability.h>11#include <linux/module.h>12#include <linux/compat.h>13#include <linux/mount.h>14#include <linux/blkdev.h>15#include <linux/backing-dev.h>16#include <linux/fsnotify.h>17#include <linux/security.h>18#include <linux/falloc.h>19#include "fat.h"20 21static long fat_fallocate(struct file *file, int mode,22 loff_t offset, loff_t len);23 24static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)25{26 u32 attr;27 28 inode_lock_shared(inode);29 attr = fat_make_attrs(inode);30 inode_unlock_shared(inode);31 32 return put_user(attr, user_attr);33}34 35static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)36{37 struct inode *inode = file_inode(file);38 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);39 int is_dir = S_ISDIR(inode->i_mode);40 u32 attr, oldattr;41 struct iattr ia;42 int err;43 44 err = get_user(attr, user_attr);45 if (err)46 goto out;47 48 err = mnt_want_write_file(file);49 if (err)50 goto out;51 inode_lock(inode);52 53 /*54 * ATTR_VOLUME and ATTR_DIR cannot be changed; this also55 * prevents the user from turning us into a VFAT56 * longname entry. Also, we obviously can't set57 * any of the NTFS attributes in the high 24 bits.58 */59 attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR);60 /* Merge in ATTR_VOLUME and ATTR_DIR */61 attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) |62 (is_dir ? ATTR_DIR : 0);63 oldattr = fat_make_attrs(inode);64 65 /* Equivalent to a chmod() */66 ia.ia_valid = ATTR_MODE | ATTR_CTIME;67 ia.ia_ctime = current_time(inode);68 if (is_dir)69 ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO);70 else {71 ia.ia_mode = fat_make_mode(sbi, attr,72 S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO));73 }74 75 /* The root directory has no attributes */76 if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {77 err = -EINVAL;78 goto out_unlock_inode;79 }80 81 if (sbi->options.sys_immutable &&82 ((attr | oldattr) & ATTR_SYS) &&83 !capable(CAP_LINUX_IMMUTABLE)) {84 err = -EPERM;85 goto out_unlock_inode;86 }87 88 /*89 * The security check is questionable... We single90 * out the RO attribute for checking by the security91 * module, just because it maps to a file mode.92 */93 err = security_inode_setattr(file_mnt_idmap(file),94 file->f_path.dentry, &ia);95 if (err)96 goto out_unlock_inode;97 98 /* This MUST be done before doing anything irreversible... */99 err = fat_setattr(file_mnt_idmap(file), file->f_path.dentry, &ia);100 if (err)101 goto out_unlock_inode;102 103 fsnotify_change(file->f_path.dentry, ia.ia_valid);104 if (sbi->options.sys_immutable) {105 if (attr & ATTR_SYS)106 inode->i_flags |= S_IMMUTABLE;107 else108 inode->i_flags &= ~S_IMMUTABLE;109 }110 111 fat_save_attrs(inode, attr);112 mark_inode_dirty(inode);113out_unlock_inode:114 inode_unlock(inode);115 mnt_drop_write_file(file);116out:117 return err;118}119 120static int fat_ioctl_get_volume_id(struct inode *inode, u32 __user *user_attr)121{122 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);123 return put_user(sbi->vol_id, user_attr);124}125 126static int fat_ioctl_fitrim(struct inode *inode, unsigned long arg)127{128 struct super_block *sb = inode->i_sb;129 struct fstrim_range __user *user_range;130 struct fstrim_range range;131 int err;132 133 if (!capable(CAP_SYS_ADMIN))134 return -EPERM;135 136 if (!bdev_max_discard_sectors(sb->s_bdev))137 return -EOPNOTSUPP;138 139 user_range = (struct fstrim_range __user *)arg;140 if (copy_from_user(&range, user_range, sizeof(range)))141 return -EFAULT;142 143 range.minlen = max_t(unsigned int, range.minlen,144 bdev_discard_granularity(sb->s_bdev));145 146 err = fat_trim_fs(inode, &range);147 if (err < 0)148 return err;149 150 if (copy_to_user(user_range, &range, sizeof(range)))151 return -EFAULT;152 153 return 0;154}155 156long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)157{158 struct inode *inode = file_inode(filp);159 u32 __user *user_attr = (u32 __user *)arg;160 161 switch (cmd) {162 case FAT_IOCTL_GET_ATTRIBUTES:163 return fat_ioctl_get_attributes(inode, user_attr);164 case FAT_IOCTL_SET_ATTRIBUTES:165 return fat_ioctl_set_attributes(filp, user_attr);166 case FAT_IOCTL_GET_VOLUME_ID:167 return fat_ioctl_get_volume_id(inode, user_attr);168 case FITRIM:169 return fat_ioctl_fitrim(inode, arg);170 default:171 return -ENOTTY; /* Inappropriate ioctl for device */172 }173}174 175static int fat_file_release(struct inode *inode, struct file *filp)176{177 if ((filp->f_mode & FMODE_WRITE) &&178 MSDOS_SB(inode->i_sb)->options.flush) {179 fat_flush_inodes(inode->i_sb, inode, NULL);180 set_current_state(TASK_UNINTERRUPTIBLE);181 io_schedule_timeout(HZ/10);182 }183 return 0;184}185 186int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)187{188 struct inode *inode = filp->f_mapping->host;189 int err;190 191 err = __generic_file_fsync(filp, start, end, datasync);192 if (err)193 return err;194 195 err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);196 if (err)197 return err;198 199 return blkdev_issue_flush(inode->i_sb->s_bdev);200}201 202 203const struct file_operations fat_file_operations = {204 .llseek = generic_file_llseek,205 .read_iter = generic_file_read_iter,206 .write_iter = generic_file_write_iter,207 .mmap = generic_file_mmap,208 .release = fat_file_release,209 .unlocked_ioctl = fat_generic_ioctl,210 .compat_ioctl = compat_ptr_ioctl,211 .fsync = fat_file_fsync,212 .splice_read = filemap_splice_read,213 .splice_write = iter_file_splice_write,214 .fallocate = fat_fallocate,215};216 217static int fat_cont_expand(struct inode *inode, loff_t size)218{219 struct address_space *mapping = inode->i_mapping;220 loff_t start = inode->i_size, count = size - inode->i_size;221 int err;222 223 err = generic_cont_expand_simple(inode, size);224 if (err)225 goto out;226 227 fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);228 mark_inode_dirty(inode);229 if (IS_SYNC(inode)) {230 int err2;231 232 /*233 * Opencode syncing since we don't have a file open to use234 * standard fsync path.235 */236 err = filemap_fdatawrite_range(mapping, start,237 start + count - 1);238 err2 = sync_mapping_buffers(mapping);239 if (!err)240 err = err2;241 err2 = write_inode_now(inode, 1);242 if (!err)243 err = err2;244 if (!err) {245 err = filemap_fdatawait_range(mapping, start,246 start + count - 1);247 }248 }249out:250 return err;251}252 253/*254 * Preallocate space for a file. This implements fat's fallocate file255 * operation, which gets called from sys_fallocate system call. User256 * space requests len bytes at offset. If FALLOC_FL_KEEP_SIZE is set257 * we just allocate clusters without zeroing them out. Otherwise we258 * allocate and zero out clusters via an expanding truncate.259 */260static long fat_fallocate(struct file *file, int mode,261 loff_t offset, loff_t len)262{263 int nr_cluster; /* Number of clusters to be allocated */264 loff_t mm_bytes; /* Number of bytes to be allocated for file */265 loff_t ondisksize; /* block aligned on-disk size in bytes*/266 struct inode *inode = file->f_mapping->host;267 struct super_block *sb = inode->i_sb;268 struct msdos_sb_info *sbi = MSDOS_SB(sb);269 int err = 0;270 271 /* No support for hole punch or other fallocate flags. */272 if (mode & ~FALLOC_FL_KEEP_SIZE)273 return -EOPNOTSUPP;274 275 /* No support for dir */276 if (!S_ISREG(inode->i_mode))277 return -EOPNOTSUPP;278 279 inode_lock(inode);280 if (mode & FALLOC_FL_KEEP_SIZE) {281 ondisksize = inode->i_blocks << 9;282 if ((offset + len) <= ondisksize)283 goto error;284 285 /* First compute the number of clusters to be allocated */286 mm_bytes = offset + len - ondisksize;287 nr_cluster = (mm_bytes + (sbi->cluster_size - 1)) >>288 sbi->cluster_bits;289 290 /* Start the allocation.We are not zeroing out the clusters */291 while (nr_cluster-- > 0) {292 err = fat_add_cluster(inode);293 if (err)294 goto error;295 }296 } else {297 if ((offset + len) <= i_size_read(inode))298 goto error;299 300 /* This is just an expanding truncate */301 err = fat_cont_expand(inode, (offset + len));302 }303 304error:305 inode_unlock(inode);306 return err;307}308 309/* Free all clusters after the skip'th cluster. */310static int fat_free(struct inode *inode, int skip)311{312 struct super_block *sb = inode->i_sb;313 int err, wait, free_start, i_start, i_logstart;314 315 if (MSDOS_I(inode)->i_start == 0)316 return 0;317 318 fat_cache_inval_inode(inode);319 320 wait = IS_DIRSYNC(inode);321 i_start = free_start = MSDOS_I(inode)->i_start;322 i_logstart = MSDOS_I(inode)->i_logstart;323 324 /* First, we write the new file size. */325 if (!skip) {326 MSDOS_I(inode)->i_start = 0;327 MSDOS_I(inode)->i_logstart = 0;328 }329 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;330 fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);331 if (wait) {332 err = fat_sync_inode(inode);333 if (err) {334 MSDOS_I(inode)->i_start = i_start;335 MSDOS_I(inode)->i_logstart = i_logstart;336 return err;337 }338 } else339 mark_inode_dirty(inode);340 341 /* Write a new EOF, and get the remaining cluster chain for freeing. */342 if (skip) {343 struct fat_entry fatent;344 int ret, fclus, dclus;345 346 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);347 if (ret < 0)348 return ret;349 else if (ret == FAT_ENT_EOF)350 return 0;351 352 fatent_init(&fatent);353 ret = fat_ent_read(inode, &fatent, dclus);354 if (ret == FAT_ENT_EOF) {355 fatent_brelse(&fatent);356 return 0;357 } else if (ret == FAT_ENT_FREE) {358 fat_fs_error(sb,359 "%s: invalid cluster chain (i_pos %lld)",360 __func__, MSDOS_I(inode)->i_pos);361 ret = -EIO;362 } else if (ret > 0) {363 err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);364 if (err)365 ret = err;366 }367 fatent_brelse(&fatent);368 if (ret < 0)369 return ret;370 371 free_start = ret;372 }373 inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);374 375 /* Freeing the remained cluster chain */376 return fat_free_clusters(inode, free_start);377}378 379void fat_truncate_blocks(struct inode *inode, loff_t offset)380{381 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);382 const unsigned int cluster_size = sbi->cluster_size;383 int nr_clusters;384 385 /*386 * This protects against truncating a file bigger than it was then387 * trying to write into the hole.388 */389 if (MSDOS_I(inode)->mmu_private > offset)390 MSDOS_I(inode)->mmu_private = offset;391 392 nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;393 394 fat_free(inode, nr_clusters);395 fat_flush_inodes(inode->i_sb, inode, NULL);396}397 398int fat_getattr(struct mnt_idmap *idmap, const struct path *path,399 struct kstat *stat, u32 request_mask, unsigned int flags)400{401 struct inode *inode = d_inode(path->dentry);402 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);403 404 generic_fillattr(idmap, request_mask, inode, stat);405 stat->blksize = sbi->cluster_size;406 407 if (sbi->options.nfs == FAT_NFS_NOSTALE_RO) {408 /* Use i_pos for ino. This is used as fileid of nfs. */409 stat->ino = fat_i_pos_read(sbi, inode);410 }411 412 if (sbi->options.isvfat && request_mask & STATX_BTIME) {413 stat->result_mask |= STATX_BTIME;414 stat->btime = MSDOS_I(inode)->i_crtime;415 }416 417 return 0;418}419EXPORT_SYMBOL_GPL(fat_getattr);420 421static int fat_sanitize_mode(const struct msdos_sb_info *sbi,422 struct inode *inode, umode_t *mode_ptr)423{424 umode_t mask, perm;425 426 /*427 * Note, the basic check is already done by a caller of428 * (attr->ia_mode & ~FAT_VALID_MODE)429 */430 431 if (S_ISREG(inode->i_mode))432 mask = sbi->options.fs_fmask;433 else434 mask = sbi->options.fs_dmask;435 436 perm = *mode_ptr & ~(S_IFMT | mask);437 438 /*439 * Of the r and x bits, all (subject to umask) must be present. Of the440 * w bits, either all (subject to umask) or none must be present.441 *442 * If fat_mode_can_hold_ro(inode) is false, can't change w bits.443 */444 if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))445 return -EPERM;446 if (fat_mode_can_hold_ro(inode)) {447 if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))448 return -EPERM;449 } else {450 if ((perm & S_IWUGO) != (S_IWUGO & ~mask))451 return -EPERM;452 }453 454 *mode_ptr &= S_IFMT | perm;455 456 return 0;457}458 459static int fat_allow_set_time(struct mnt_idmap *idmap,460 struct msdos_sb_info *sbi, struct inode *inode)461{462 umode_t allow_utime = sbi->options.allow_utime;463 464 if (!vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode),465 current_fsuid())) {466 if (vfsgid_in_group_p(i_gid_into_vfsgid(idmap, inode)))467 allow_utime >>= 3;468 if (allow_utime & MAY_WRITE)469 return 1;470 }471 472 /* use a default check */473 return 0;474}475 476#define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)477/* valid file mode bits */478#define FAT_VALID_MODE (S_IFREG | S_IFDIR | S_IRWXUGO)479 480int fat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,481 struct iattr *attr)482{483 struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);484 struct inode *inode = d_inode(dentry);485 unsigned int ia_valid;486 int error;487 488 /* Check for setting the inode time. */489 ia_valid = attr->ia_valid;490 if (ia_valid & TIMES_SET_FLAGS) {491 if (fat_allow_set_time(idmap, sbi, inode))492 attr->ia_valid &= ~TIMES_SET_FLAGS;493 }494 495 error = setattr_prepare(idmap, dentry, attr);496 attr->ia_valid = ia_valid;497 if (error) {498 if (sbi->options.quiet)499 error = 0;500 goto out;501 }502 503 /*504 * Expand the file. Since inode_setattr() updates ->i_size505 * before calling the ->truncate(), but FAT needs to fill the506 * hole before it. XXX: this is no longer true with new truncate507 * sequence.508 */509 if (attr->ia_valid & ATTR_SIZE) {510 inode_dio_wait(inode);511 512 if (attr->ia_size > inode->i_size) {513 error = fat_cont_expand(inode, attr->ia_size);514 if (error || attr->ia_valid == ATTR_SIZE)515 goto out;516 attr->ia_valid &= ~ATTR_SIZE;517 }518 }519 520 if (((attr->ia_valid & ATTR_UID) &&521 (!uid_eq(from_vfsuid(idmap, i_user_ns(inode), attr->ia_vfsuid),522 sbi->options.fs_uid))) ||523 ((attr->ia_valid & ATTR_GID) &&524 (!gid_eq(from_vfsgid(idmap, i_user_ns(inode), attr->ia_vfsgid),525 sbi->options.fs_gid))) ||526 ((attr->ia_valid & ATTR_MODE) &&527 (attr->ia_mode & ~FAT_VALID_MODE)))528 error = -EPERM;529 530 if (error) {531 if (sbi->options.quiet)532 error = 0;533 goto out;534 }535 536 /*537 * We don't return -EPERM here. Yes, strange, but this is too538 * old behavior.539 */540 if (attr->ia_valid & ATTR_MODE) {541 if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)542 attr->ia_valid &= ~ATTR_MODE;543 }544 545 if (attr->ia_valid & ATTR_SIZE) {546 error = fat_block_truncate_page(inode, attr->ia_size);547 if (error)548 goto out;549 down_write(&MSDOS_I(inode)->truncate_lock);550 truncate_setsize(inode, attr->ia_size);551 fat_truncate_blocks(inode, attr->ia_size);552 up_write(&MSDOS_I(inode)->truncate_lock);553 }554 555 /*556 * setattr_copy can't truncate these appropriately, so we'll557 * copy them ourselves558 */559 if (attr->ia_valid & ATTR_ATIME)560 fat_truncate_time(inode, &attr->ia_atime, S_ATIME);561 if (attr->ia_valid & ATTR_CTIME)562 fat_truncate_time(inode, &attr->ia_ctime, S_CTIME);563 if (attr->ia_valid & ATTR_MTIME)564 fat_truncate_time(inode, &attr->ia_mtime, S_MTIME);565 attr->ia_valid &= ~(ATTR_ATIME|ATTR_CTIME|ATTR_MTIME);566 567 setattr_copy(idmap, inode, attr);568 mark_inode_dirty(inode);569out:570 return error;571}572EXPORT_SYMBOL_GPL(fat_setattr);573 574const struct inode_operations fat_file_inode_operations = {575 .setattr = fat_setattr,576 .getattr = fat_getattr,577 .update_time = fat_update_time,578};579