1 files changed, 578 insertions, 0 deletions

diff --git a/fs/fat/file.c b/fs/fat/file.c
new file mode 100644
index 0000000000..e887e9ab74
--- /dev/null
+++ b/fs/fat/file.c
@@ -0,0 +1,578 @@
+// 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_idmap(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_idmap(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	= filemap_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 mnt_idmap *idmap, 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(idmap, request_mask, 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 mnt_idmap *idmap,
+			      struct msdos_sb_info *sbi, struct inode *inode)
+{
+	umode_t allow_utime = sbi->options.allow_utime;
+
+	if (!vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode),
+			    current_fsuid())) {
+		if (vfsgid_in_group_p(i_gid_into_vfsgid(idmap, 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 mnt_idmap *idmap, 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(idmap, sbi, inode))
+			attr->ia_valid &= ~TIMES_SET_FLAGS;
+	}
+
+	error = setattr_prepare(idmap, 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(idmap, i_user_ns(inode), attr->ia_vfsuid),
+		      sbi->options.fs_uid))) ||
+	    ((attr->ia_valid & ATTR_GID) &&
+	     (!gid_eq(from_vfsgid(idmap, 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(idmap, 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,
+};