// SPDX-License-Identifier: GPL-2.0-only /* * linux/fs/fat/file.c * * Written 1992,1993 by Werner Almesberger * * regular file handling primitives for fat-based filesystems */ #include <linux/capability.h> #include <linux/module.h> #include <linux/compat.h> #include <linux/mount.h> #include <linux/blkdev.h> #include <linux/backing-dev.h> #include <linux/fsnotify.h> #include <linux/security.h> #include <linux/falloc.h> #include "fat.h" static long fat_fallocate(struct file *file, int mode, loff_t offset, loff_t len); static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr) { u32 attr; inode_lock_shared(inode); attr = fat_make_attrs(inode); inode_unlock_shared(inode); return put_user(attr, user_attr); } static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr) { struct inode *inode = file_inode(file); struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); int is_dir = S_ISDIR(inode->i_mode); u32 attr, oldattr; struct iattr ia; int err; err = get_user(attr, user_attr); if (err) goto out; err = mnt_want_write_file(file); if (err) goto out; inode_lock(inode); /* * ATTR_VOLUME and ATTR_DIR cannot be changed; this also * prevents the user from turning us into a VFAT * longname entry. Also, we obviously can't set * any of the NTFS attributes in the high 24 bits. */ attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR); /* Merge in ATTR_VOLUME and ATTR_DIR */ attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) | (is_dir ? ATTR_DIR : 0); oldattr = fat_make_attrs(inode); /* Equivalent to a chmod() */ ia.ia_valid = ATTR_MODE | ATTR_CTIME; ia.ia_ctime = current_time(inode); if (is_dir) ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO); else { ia.ia_mode = fat_make_mode(sbi, attr, S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO)); } /* The root directory has no attributes */ if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) { err = -EINVAL; goto out_unlock_inode; } if (sbi->options.sys_immutable && ((attr | oldattr) & ATTR_SYS) && !capable(CAP_LINUX_IMMUTABLE)) { err = -EPERM; goto out_unlock_inode; } /* * The security check is questionable... We single * out the RO attribute for checking by the security * module, just because it maps to a file mode. */ err = security_inode_setattr(file_mnt_user_ns(file), file->f_path.dentry, &ia); if (err) goto out_unlock_inode; /* This MUST be done before doing anything irreversible... */ err = fat_setattr(file_mnt_user_ns(file), file->f_path.dentry, &ia); if (err) goto out_unlock_inode; fsnotify_change(file->f_path.dentry, ia.ia_valid); if (sbi->options.sys_immutable) { if (attr & ATTR_SYS) inode->i_flags |= S_IMMUTABLE; else inode->i_flags &= ~S_IMMUTABLE; } fat_save_attrs(inode, attr); mark_inode_dirty(inode); out_unlock_inode: inode_unlock(inode); mnt_drop_write_file(file); out: return err; } static int fat_ioctl_get_volume_id(struct inode *inode, u32 __user *user_attr) { struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); return put_user(sbi->vol_id, user_attr); } static int fat_ioctl_fitrim(struct inode *inode, unsigned long arg) { struct super_block *sb = inode->i_sb; struct fstrim_range __user *user_range; struct fstrim_range range; int err; if (!capable(CAP_SYS_ADMIN)) return -EPERM; if (!bdev_max_discard_sectors(sb->s_bdev)) return -EOPNOTSUPP; user_range = (struct fstrim_range __user *)arg; if (copy_from_user(&range, user_range, sizeof(range))) return -EFAULT; range.minlen = max_t(unsigned int, range.minlen, bdev_discard_granularity(sb->s_bdev)); err = fat_trim_fs(inode, &range); if (err < 0) return err; if (copy_to_user(user_range, &range, sizeof(range))) return -EFAULT; return 0; } long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { struct inode *inode = file_inode(filp); u32 __user *user_attr = (u32 __user *)arg; switch (cmd) { case FAT_IOCTL_GET_ATTRIBUTES: return fat_ioctl_get_attributes(inode, user_attr); case FAT_IOCTL_SET_ATTRIBUTES: return fat_ioctl_set_attributes(filp, user_attr); case FAT_IOCTL_GET_VOLUME_ID: return fat_ioctl_get_volume_id(inode, user_attr); case FITRIM: return fat_ioctl_fitrim(inode, arg); default: return -ENOTTY; /* Inappropriate ioctl for device */ } } static int fat_file_release(struct inode *inode, struct file *filp) { if ((filp->f_mode & FMODE_WRITE) && MSDOS_SB(inode->i_sb)->options.flush) { fat_flush_inodes(inode->i_sb, inode, NULL); set_current_state(TASK_UNINTERRUPTIBLE); io_schedule_timeout(HZ/10); } return 0; } int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync) { struct inode *inode = filp->f_mapping->host; int err; err = __generic_file_fsync(filp, start, end, datasync); if (err) return err; err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping); if (err) return err; return blkdev_issue_flush(inode->i_sb->s_bdev); } const struct file_operations fat_file_operations = { .llseek = generic_file_llseek, .read_iter = generic_file_read_iter, .write_iter = generic_file_write_iter, .mmap = generic_file_mmap, .release = fat_file_release, .unlocked_ioctl = fat_generic_ioctl, .compat_ioctl = compat_ptr_ioctl, .fsync = fat_file_fsync, .splice_read = generic_file_splice_read, .splice_write = iter_file_splice_write, .fallocate = fat_fallocate, }; static int fat_cont_expand(struct inode *inode, loff_t size) { struct address_space *mapping = inode->i_mapping; loff_t start = inode->i_size, count = size - inode->i_size; int err; err = generic_cont_expand_simple(inode, size); if (err) goto out; fat_truncate_time(inode, NULL, S_CTIME|S_MTIME); mark_inode_dirty(inode); if (IS_SYNC(inode)) { int err2; /* * Opencode syncing since we don't have a file open to use * standard fsync path. */ err = filemap_fdatawrite_range(mapping, start, start + count - 1); err2 = sync_mapping_buffers(mapping); if (!err) err = err2; err2 = write_inode_now(inode, 1); if (!err) err = err2; if (!err) { err = filemap_fdatawait_range(mapping, start, start + count - 1); } } out: return err; } /* * Preallocate space for a file. This implements fat's fallocate file * operation, which gets called from sys_fallocate system call. User * space requests len bytes at offset. If FALLOC_FL_KEEP_SIZE is set * we just allocate clusters without zeroing them out. Otherwise we * allocate and zero out clusters via an expanding truncate. */ static long fat_fallocate(struct file *file, int mode, loff_t offset, loff_t len) { int nr_cluster; /* Number of clusters to be allocated */ loff_t mm_bytes; /* Number of bytes to be allocated for file */ loff_t ondisksize; /* block aligned on-disk size in bytes*/ struct inode *inode = file->f_mapping->host; struct super_block *sb = inode->i_sb; struct msdos_sb_info *sbi = MSDOS_SB(sb); int err = 0; /* No support for hole punch or other fallocate flags. */ if (mode & ~FALLOC_FL_KEEP_SIZE) return -EOPNOTSUPP; /* No support for dir */ if (!S_ISREG(inode->i_mode)) return -EOPNOTSUPP; inode_lock(inode); if (mode & FALLOC_FL_KEEP_SIZE) { ondisksize = inode->i_blocks << 9; if ((offset + len) <= ondisksize) goto error; /* First compute the number of clusters to be allocated */ mm_bytes = offset + len - ondisksize; nr_cluster = (mm_bytes + (sbi->cluster_size - 1)) >> sbi->cluster_bits; /* Start the allocation.We are not zeroing out the clusters */ while (nr_cluster-- > 0) { err = fat_add_cluster(inode); if (err) goto error; } } else { if ((offset + len) <= i_size_read(inode)) goto error; /* This is just an expanding truncate */ err = fat_cont_expand(inode, (offset + len)); } error: inode_unlock(inode); return err; } /* Free all clusters after the skip'th cluster. */ static int fat_free(struct inode *inode, int skip) { struct super_block *sb = inode->i_sb; int err, wait, free_start, i_start, i_logstart; if (MSDOS_I(inode)->i_start == 0) return 0; fat_cache_inval_inode(inode); wait = IS_DIRSYNC(inode); i_start = free_start = MSDOS_I(inode)->i_start; i_logstart = MSDOS_I(inode)->i_logstart; /* First, we write the new file size. */ if (!skip) { MSDOS_I(inode)->i_start = 0; MSDOS_I(inode)->i_logstart = 0; } MSDOS_I(inode)->i_attrs |= ATTR_ARCH; fat_truncate_time(inode, NULL, S_CTIME|S_MTIME); if (wait) { err = fat_sync_inode(inode); if (err) { MSDOS_I(inode)->i_start = i_start; MSDOS_I(inode)->i_logstart = i_logstart; return err; } } else mark_inode_dirty(inode); /* Write a new EOF, and get the remaining cluster chain for freeing. */ if (skip) { struct fat_entry fatent; int ret, fclus, dclus; ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus); if (ret < 0) return ret; else if (ret == FAT_ENT_EOF) return 0; fatent_init(&fatent); ret = fat_ent_read(inode, &fatent, dclus); if (ret == FAT_ENT_EOF) { fatent_brelse(&fatent); return 0; } else if (ret == FAT_ENT_FREE) { fat_fs_error(sb, "%s: invalid cluster chain (i_pos %lld)", __func__, MSDOS_I(inode)->i_pos); ret = -EIO; } else if (ret > 0) { err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait); if (err) ret = err; } fatent_brelse(&fatent); if (ret < 0) return ret; free_start = ret; } inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9); /* Freeing the remained cluster chain */ return fat_free_clusters(inode, free_start); } void fat_truncate_blocks(struct inode *inode, loff_t offset) { struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); const unsigned int cluster_size = sbi->cluster_size; int nr_clusters; /* * This protects against truncating a file bigger than it was then * trying to write into the hole. */ if (MSDOS_I(inode)->mmu_private > offset) MSDOS_I(inode)->mmu_private = offset; nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits; fat_free(inode, nr_clusters); fat_flush_inodes(inode->i_sb, inode, NULL); } int fat_getattr(struct user_namespace *mnt_userns, const struct path *path, struct kstat *stat, u32 request_mask, unsigned int flags) { struct inode *inode = d_inode(path->dentry); struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); generic_fillattr(mnt_userns, inode, stat); stat->blksize = sbi->cluster_size; if (sbi->options.nfs == FAT_NFS_NOSTALE_RO) { /* Use i_pos for ino. This is used as fileid of nfs. */ stat->ino = fat_i_pos_read(sbi, inode); } if (sbi->options.isvfat && request_mask & STATX_BTIME) { stat->result_mask |= STATX_BTIME; stat->btime = MSDOS_I(inode)->i_crtime; } return 0; } EXPORT_SYMBOL_GPL(fat_getattr); static int fat_sanitize_mode(const struct msdos_sb_info *sbi, struct inode *inode, umode_t *mode_ptr) { umode_t mask, perm; /* * Note, the basic check is already done by a caller of * (attr->ia_mode & ~FAT_VALID_MODE) */ if (S_ISREG(inode->i_mode)) mask = sbi->options.fs_fmask; else mask = sbi->options.fs_dmask; perm = *mode_ptr & ~(S_IFMT | mask); /* * Of the r and x bits, all (subject to umask) must be present. Of the * w bits, either all (subject to umask) or none must be present. * * If fat_mode_can_hold_ro(inode) is false, can't change w bits. */ if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO))) return -EPERM; if (fat_mode_can_hold_ro(inode)) { if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask))) return -EPERM; } else { if ((perm & S_IWUGO) != (S_IWUGO & ~mask)) return -EPERM; } *mode_ptr &= S_IFMT | perm; return 0; } static int fat_allow_set_time(struct user_namespace *mnt_userns, struct msdos_sb_info *sbi, struct inode *inode) { umode_t allow_utime = sbi->options.allow_utime; if (!vfsuid_eq_kuid(i_uid_into_vfsuid(mnt_userns, inode), current_fsuid())) { if (vfsgid_in_group_p(i_gid_into_vfsgid(mnt_userns, inode))) allow_utime >>= 3; if (allow_utime & MAY_WRITE) return 1; } /* use a default check */ return 0; } #define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET) /* valid file mode bits */ #define FAT_VALID_MODE (S_IFREG | S_IFDIR | S_IRWXUGO) int fat_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, struct iattr *attr) { struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb); struct inode *inode = d_inode(dentry); unsigned int ia_valid; int error; /* Check for setting the inode time. */ ia_valid = attr->ia_valid; if (ia_valid & TIMES_SET_FLAGS) { if (fat_allow_set_time(mnt_userns, sbi, inode)) attr->ia_valid &= ~TIMES_SET_FLAGS; } error = setattr_prepare(mnt_userns, dentry, attr); attr->ia_valid = ia_valid; if (error) { if (sbi->options.quiet) error = 0; goto out; } /* * Expand the file. Since inode_setattr() updates ->i_size * before calling the ->truncate(), but FAT needs to fill the * hole before it. XXX: this is no longer true with new truncate * sequence. */ if (attr->ia_valid & ATTR_SIZE) { inode_dio_wait(inode); if (attr->ia_size > inode->i_size) { error = fat_cont_expand(inode, attr->ia_size); if (error || attr->ia_valid == ATTR_SIZE) goto out; attr->ia_valid &= ~ATTR_SIZE; } } if (((attr->ia_valid & ATTR_UID) && (!uid_eq(from_vfsuid(mnt_userns, i_user_ns(inode), attr->ia_vfsuid), sbi->options.fs_uid))) || ((attr->ia_valid & ATTR_GID) && (!gid_eq(from_vfsgid(mnt_userns, i_user_ns(inode), attr->ia_vfsgid), sbi->options.fs_gid))) || ((attr->ia_valid & ATTR_MODE) && (attr->ia_mode & ~FAT_VALID_MODE))) error = -EPERM; if (error) { if (sbi->options.quiet) error = 0; goto out; } /* * We don't return -EPERM here. Yes, strange, but this is too * old behavior. */ if (attr->ia_valid & ATTR_MODE) { if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0) attr->ia_valid &= ~ATTR_MODE; } if (attr->ia_valid & ATTR_SIZE) { error = fat_block_truncate_page(inode, attr->ia_size); if (error) goto out; down_write(&MSDOS_I(inode)->truncate_lock); truncate_setsize(inode, attr->ia_size); fat_truncate_blocks(inode, attr->ia_size); up_write(&MSDOS_I(inode)->truncate_lock); } /* * setattr_copy can't truncate these appropriately, so we'll * copy them ourselves */ if (attr->ia_valid & ATTR_ATIME) fat_truncate_time(inode, &attr->ia_atime, S_ATIME); if (attr->ia_valid & ATTR_CTIME) fat_truncate_time(inode, &attr->ia_ctime, S_CTIME); if (attr->ia_valid & ATTR_MTIME) fat_truncate_time(inode, &attr->ia_mtime, S_MTIME); attr->ia_valid &= ~(ATTR_ATIME|ATTR_CTIME|ATTR_MTIME); setattr_copy(mnt_userns, inode, attr); mark_inode_dirty(inode); out: return error; } EXPORT_SYMBOL_GPL(fat_setattr); const struct inode_operations fat_file_inode_operations = { .setattr = fat_setattr, .getattr = fat_getattr, .update_time = fat_update_time, };