Exemplo n.º 1
0
ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
{
	struct dentry *realdentry = ovl_dentry_real(dentry);
	ssize_t res;
	size_t len;
	char *s;
	const struct cred *old_cred;

	old_cred = ovl_override_creds(dentry->d_sb);
	res = vfs_listxattr(realdentry, list, size);
	revert_creds(old_cred);
	if (res <= 0 || size == 0)
		return res;

	/* filter out private xattrs */
	for (s = list, len = res; len;) {
		size_t slen = strnlen(s, len) + 1;

		/* underlying fs providing us with an broken xattr list? */
		if (WARN_ON(slen > len))
			return -EIO;

		len -= slen;
		if (!ovl_can_list(s)) {
			res -= slen;
			memmove(s, s + slen, len);
		} else {
			s += slen;
		}
	}

	return res;
}
Exemplo n.º 2
0
Arquivo: file.c Projeto: Lyude/linux
static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
	struct file *file = iocb->ki_filp;
	struct fd real;
	const struct cred *old_cred;
	ssize_t ret;

	if (!iov_iter_count(iter))
		return 0;

	ret = ovl_real_fdget(file, &real);
	if (ret)
		return ret;

	old_cred = ovl_override_creds(file_inode(file)->i_sb);
	ret = vfs_iter_read(real.file, iter, &iocb->ki_pos,
			    ovl_iocb_to_rwf(iocb));
	revert_creds(old_cred);

	ovl_file_accessed(file);

	fdput(real);

	return ret;
}
Exemplo n.º 3
0
int ovl_permission(struct inode *inode, int mask)
{
	struct inode *upperinode = ovl_inode_upper(inode);
	struct inode *realinode = upperinode ?: ovl_inode_lower(inode);
	const struct cred *old_cred;
	int err;

	/* Careful in RCU walk mode */
	if (!realinode) {
		WARN_ON(!(mask & MAY_NOT_BLOCK));
		return -ECHILD;
	}

	/*
	 * Check overlay inode with the creds of task and underlying inode
	 * with creds of mounter
	 */
	err = generic_permission(inode, mask);
	if (err)
		return err;

	old_cred = ovl_override_creds(inode->i_sb);
	if (!upperinode &&
	    !special_file(realinode->i_mode) && mask & MAY_WRITE) {
		mask &= ~(MAY_WRITE | MAY_APPEND);
		/* Make sure mounter can read file for copy up later */
		mask |= MAY_READ;
	}
	err = inode_permission(realinode, mask);
	revert_creds(old_cred);

	return err;
}
Exemplo n.º 4
0
Arquivo: file.c Projeto: Lyude/linux
static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
{
	struct file *realfile = file->private_data;
	const struct cred *old_cred;
	int ret;

	if (!realfile->f_op->mmap)
		return -ENODEV;

	if (WARN_ON(file != vma->vm_file))
		return -EIO;

	vma->vm_file = get_file(realfile);

	old_cred = ovl_override_creds(file_inode(file)->i_sb);
	ret = call_mmap(vma->vm_file, vma);
	revert_creds(old_cred);

	if (ret) {
		/* Drop reference count from new vm_file value */
		fput(realfile);
	} else {
		/* Drop reference count from previous vm_file value */
		fput(file);
	}

	ovl_file_accessed(file);

	return ret;
}
Exemplo n.º 5
0
Arquivo: dir.c Projeto: gxt/linux
static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
			 struct kstat *stat)
{
	int err;
	enum ovl_path_type type;
	struct path realpath;
	const struct cred *old_cred;

	type = ovl_path_real(dentry, &realpath);
	old_cred = ovl_override_creds(dentry->d_sb);
	err = vfs_getattr(&realpath, stat);
	revert_creds(old_cred);
	if (err)
		return err;

	stat->dev = dentry->d_sb->s_dev;
	stat->ino = dentry->d_inode->i_ino;

	/*
	 * It's probably not worth it to count subdirs to get the
	 * correct link count.  nlink=1 seems to pacify 'find' and
	 * other utilities.
	 */
	if (OVL_TYPE_MERGE(type))
		stat->nlink = 1;

	return 0;
}
Exemplo n.º 6
0
int ovl_xattr_get(struct dentry *dentry, const char *name,
		  void *value, size_t size)
{
	struct dentry *realdentry = ovl_dentry_real(dentry);
	ssize_t res;
	const struct cred *old_cred;

	old_cred = ovl_override_creds(dentry->d_sb);
	res = vfs_getxattr(realdentry, name, value, size);
	revert_creds(old_cred);
	return res;
}
Exemplo n.º 7
0
int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
		  void *value, size_t size)
{
	ssize_t res;
	const struct cred *old_cred;
	struct dentry *realdentry =
		ovl_i_dentry_upper(inode) ?: ovl_dentry_lower(dentry);

	old_cred = ovl_override_creds(dentry->d_sb);
	res = vfs_getxattr(realdentry, name, value, size);
	revert_creds(old_cred);
	return res;
}
Exemplo n.º 8
0
static const char *ovl_get_link(struct dentry *dentry,
				struct inode *inode,
				struct delayed_call *done)
{
	const struct cred *old_cred;
	const char *p;

	if (!dentry)
		return ERR_PTR(-ECHILD);

	old_cred = ovl_override_creds(dentry->d_sb);
	p = vfs_get_link(ovl_dentry_real(dentry), done);
	revert_creds(old_cred);
	return p;
}
Exemplo n.º 9
0
struct posix_acl *ovl_get_acl(struct inode *inode, int type)
{
	struct inode *realinode = ovl_inode_real(inode);
	const struct cred *old_cred;
	struct posix_acl *acl;

	if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !IS_POSIXACL(realinode))
		return NULL;

	old_cred = ovl_override_creds(inode->i_sb);
	acl = get_acl(realinode, type);
	revert_creds(old_cred);

	return acl;
}
Exemplo n.º 10
0
Arquivo: file.c Projeto: avagin/linux
static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in,
			    struct file *file_out, loff_t pos_out,
			    loff_t len, unsigned int flags, enum ovl_copyop op)
{
	struct inode *inode_out = file_inode(file_out);
	struct fd real_in, real_out;
	const struct cred *old_cred;
	loff_t ret;

	ret = ovl_real_fdget(file_out, &real_out);
	if (ret)
		return ret;

	ret = ovl_real_fdget(file_in, &real_in);
	if (ret) {
		fdput(real_out);
		return ret;
	}

	old_cred = ovl_override_creds(file_inode(file_out)->i_sb);
	switch (op) {
	case OVL_COPY:
		ret = vfs_copy_file_range(real_in.file, pos_in,
					  real_out.file, pos_out, len, flags);
		break;

	case OVL_CLONE:
		ret = vfs_clone_file_range(real_in.file, pos_in,
					   real_out.file, pos_out, len, flags);
		break;

	case OVL_DEDUPE:
		ret = vfs_dedupe_file_range_one(real_in.file, pos_in,
						real_out.file, pos_out, len,
						flags);
		break;
	}
	revert_creds(old_cred);

	/* Update size */
	ovl_copyattr(ovl_inode_real(inode_out), inode_out);

	fdput(real_in);
	fdput(real_out);

	return ret;
}
Exemplo n.º 11
0
Arquivo: file.c Projeto: Lyude/linux
static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
{
	struct fd real;
	const struct cred *old_cred;
	int ret;

	ret = ovl_real_fdget(file, &real);
	if (ret)
		return ret;

	old_cred = ovl_override_creds(file_inode(file)->i_sb);
	ret = vfs_fadvise(real.file, offset, len, advice);
	revert_creds(old_cred);

	fdput(real);

	return ret;
}
Exemplo n.º 12
0
Arquivo: file.c Projeto: Lyude/linux
static struct file *ovl_open_realfile(const struct file *file,
				      struct inode *realinode)
{
	struct inode *inode = file_inode(file);
	struct file *realfile;
	const struct cred *old_cred;

	old_cred = ovl_override_creds(inode->i_sb);
	realfile = open_with_fake_path(&file->f_path, file->f_flags | O_NOATIME,
				       realinode, current_cred());
	revert_creds(old_cred);

	pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
		 file, file, ovl_whatisit(inode, realinode), file->f_flags,
		 realfile, IS_ERR(realfile) ? 0 : realfile->f_flags);

	return realfile;
}
Exemplo n.º 13
0
Arquivo: file.c Projeto: avagin/linux
static loff_t ovl_llseek(struct file *file, loff_t offset, int whence)
{
	struct inode *inode = file_inode(file);
	struct fd real;
	const struct cred *old_cred;
	ssize_t ret;

	/*
	 * The two special cases below do not need to involve real fs,
	 * so we can optimizing concurrent callers.
	 */
	if (offset == 0) {
		if (whence == SEEK_CUR)
			return file->f_pos;

		if (whence == SEEK_SET)
			return vfs_setpos(file, 0, 0);
	}

	ret = ovl_real_fdget(file, &real);
	if (ret)
		return ret;

	/*
	 * Overlay file f_pos is the master copy that is preserved
	 * through copy up and modified on read/write, but only real
	 * fs knows how to SEEK_HOLE/SEEK_DATA and real fs may impose
	 * limitations that are more strict than ->s_maxbytes for specific
	 * files, so we use the real file to perform seeks.
	 */
	inode_lock(inode);
	real.file->f_pos = file->f_pos;

	old_cred = ovl_override_creds(inode->i_sb);
	ret = vfs_llseek(real.file, offset, whence);
	revert_creds(old_cred);

	file->f_pos = real.file->f_pos;
	inode_unlock(inode);

	fdput(real);

	return ret;
}
Exemplo n.º 14
0
Arquivo: file.c Projeto: Lyude/linux
static long ovl_real_ioctl(struct file *file, unsigned int cmd,
			   unsigned long arg)
{
	struct fd real;
	const struct cred *old_cred;
	long ret;

	ret = ovl_real_fdget(file, &real);
	if (ret)
		return ret;

	old_cred = ovl_override_creds(file_inode(file)->i_sb);
	ret = vfs_ioctl(real.file, cmd, arg);
	revert_creds(old_cred);

	fdput(real);

	return ret;
}
Exemplo n.º 15
0
int ovl_setattr(struct dentry *dentry, struct iattr *attr)
{
	int err;
	struct dentry *upperdentry;
	const struct cred *old_cred;

	/*
	 * Check for permissions before trying to copy-up.  This is redundant
	 * since it will be rechecked later by ->setattr() on upper dentry.  But
	 * without this, copy-up can be triggered by just about anybody.
	 *
	 * We don't initialize inode->size, which just means that
	 * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not
	 * check for a swapfile (which this won't be anyway).
	 */
	err = setattr_prepare(dentry, attr);
	if (err)
		return err;

	err = ovl_want_write(dentry);
	if (err)
		goto out;

	err = ovl_copy_up(dentry);
	if (!err) {
		upperdentry = ovl_dentry_upper(dentry);

		if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
			attr->ia_valid &= ~ATTR_MODE;

		inode_lock(upperdentry->d_inode);
		old_cred = ovl_override_creds(dentry->d_sb);
		err = notify_change(upperdentry, attr, NULL);
		revert_creds(old_cred);
		if (!err)
			ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
		inode_unlock(upperdentry->d_inode);
	}
	ovl_drop_write(dentry);
out:
	return err;
}
Exemplo n.º 16
0
Arquivo: file.c Projeto: Lyude/linux
static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
	struct fd real;
	const struct cred *old_cred;
	int ret;

	ret = ovl_real_fdget_meta(file, &real, !datasync);
	if (ret)
		return ret;

	/* Don't sync lower file for fear of receiving EROFS error */
	if (file_inode(real.file) == ovl_inode_upper(file_inode(file))) {
		old_cred = ovl_override_creds(file_inode(file)->i_sb);
		ret = vfs_fsync_range(real.file, start, end, datasync);
		revert_creds(old_cred);
	}

	fdput(real);

	return ret;
}
Exemplo n.º 17
0
int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
		  const void *value, size_t size, int flags)
{
	int err;
	struct dentry *upperdentry = ovl_i_dentry_upper(inode);
	struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
	const struct cred *old_cred;

	err = ovl_want_write(dentry);
	if (err)
		goto out;

	if (!value && !upperdentry) {
		err = vfs_getxattr(realdentry, name, NULL, 0);
		if (err < 0)
			goto out_drop_write;
	}

	if (!upperdentry) {
		err = ovl_copy_up(dentry);
		if (err)
			goto out_drop_write;

		realdentry = ovl_dentry_upper(dentry);
	}

	old_cred = ovl_override_creds(dentry->d_sb);
	if (value)
		err = vfs_setxattr(realdentry, name, value, size, flags);
	else {
		WARN_ON(flags != XATTR_REPLACE);
		err = vfs_removexattr(realdentry, name);
	}
	revert_creds(old_cred);

out_drop_write:
	ovl_drop_write(dentry);
out:
	return err;
}
Exemplo n.º 18
0
Arquivo: file.c Projeto: Lyude/linux
static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
{
	struct inode *inode = file_inode(file);
	struct fd real;
	const struct cred *old_cred;
	int ret;

	ret = ovl_real_fdget(file, &real);
	if (ret)
		return ret;

	old_cred = ovl_override_creds(file_inode(file)->i_sb);
	ret = vfs_fallocate(real.file, mode, offset, len);
	revert_creds(old_cred);

	/* Update size */
	ovl_copyattr(ovl_inode_real(inode), inode);

	fdput(real);

	return ret;
}
Exemplo n.º 19
0
int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value,
		  size_t size, int flags)
{
	int err;
	struct path realpath;
	enum ovl_path_type type = ovl_path_real(dentry, &realpath);
	const struct cred *old_cred;

	err = ovl_want_write(dentry);
	if (err)
		goto out;

	if (!value && !OVL_TYPE_UPPER(type)) {
		err = vfs_getxattr(realpath.dentry, name, NULL, 0);
		if (err < 0)
			goto out_drop_write;
	}

	err = ovl_copy_up(dentry);
	if (err)
		goto out_drop_write;

	if (!OVL_TYPE_UPPER(type))
		ovl_path_upper(dentry, &realpath);

	old_cred = ovl_override_creds(dentry->d_sb);
	if (value)
		err = vfs_setxattr(realpath.dentry, name, value, size, flags);
	else {
		WARN_ON(flags != XATTR_REPLACE);
		err = vfs_removexattr(realpath.dentry, name);
	}
	revert_creds(old_cred);

out_drop_write:
	ovl_drop_write(dentry);
out:
	return err;
}
Exemplo n.º 20
0
Arquivo: file.c Projeto: Lyude/linux
static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
{
	struct file *file = iocb->ki_filp;
	struct inode *inode = file_inode(file);
	struct fd real;
	const struct cred *old_cred;
	ssize_t ret;

	if (!iov_iter_count(iter))
		return 0;

	inode_lock(inode);
	/* Update mode */
	ovl_copyattr(ovl_inode_real(inode), inode);
	ret = file_remove_privs(file);
	if (ret)
		goto out_unlock;

	ret = ovl_real_fdget(file, &real);
	if (ret)
		goto out_unlock;

	old_cred = ovl_override_creds(file_inode(file)->i_sb);
	file_start_write(real.file);
	ret = vfs_iter_write(real.file, iter, &iocb->ki_pos,
			     ovl_iocb_to_rwf(iocb));
	file_end_write(real.file);
	revert_creds(old_cred);

	/* Update size */
	ovl_copyattr(ovl_inode_real(inode), inode);

	fdput(real);

out_unlock:
	inode_unlock(inode);

	return ret;
}
Exemplo n.º 21
0
Arquivo: dir.c Projeto: gxt/linux
static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
				    struct kstat *stat, const char *link,
				    struct dentry *hardlink)
{
	struct dentry *workdir = ovl_workdir(dentry);
	struct inode *wdir = workdir->d_inode;
	struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
	struct inode *udir = upperdir->d_inode;
	struct dentry *upper;
	struct dentry *newdentry;
	int err;
	struct posix_acl *acl, *default_acl;

	if (WARN_ON(!workdir))
		return -EROFS;

	if (!hardlink) {
		err = posix_acl_create(dentry->d_parent->d_inode,
				       &stat->mode, &default_acl, &acl);
		if (err)
			return err;
	}

	err = ovl_lock_rename_workdir(workdir, upperdir);
	if (err)
		goto out;

	newdentry = ovl_lookup_temp(workdir, dentry);
	err = PTR_ERR(newdentry);
	if (IS_ERR(newdentry))
		goto out_unlock;

	upper = lookup_one_len(dentry->d_name.name, upperdir,
			       dentry->d_name.len);
	err = PTR_ERR(upper);
	if (IS_ERR(upper))
		goto out_dput;

	err = ovl_create_real(wdir, newdentry, stat, link, hardlink, true);
	if (err)
		goto out_dput2;

	/*
	 * mode could have been mutilated due to umask (e.g. sgid directory)
	 */
	if (!hardlink &&
	    !S_ISLNK(stat->mode) && newdentry->d_inode->i_mode != stat->mode) {
		struct iattr attr = {
			.ia_valid = ATTR_MODE,
			.ia_mode = stat->mode,
		};
		inode_lock(newdentry->d_inode);
		err = notify_change(newdentry, &attr, NULL);
		inode_unlock(newdentry->d_inode);
		if (err)
			goto out_cleanup;
	}
	if (!hardlink) {
		err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_ACCESS,
					acl);
		if (err)
			goto out_cleanup;

		err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_DEFAULT,
					default_acl);
		if (err)
			goto out_cleanup;
	}

	if (!hardlink && S_ISDIR(stat->mode)) {
		err = ovl_set_opaque(newdentry);
		if (err)
			goto out_cleanup;

		err = ovl_do_rename(wdir, newdentry, udir, upper,
				    RENAME_EXCHANGE);
		if (err)
			goto out_cleanup;

		ovl_cleanup(wdir, upper);
	} else {
		err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
		if (err)
			goto out_cleanup;
	}
	ovl_instantiate(dentry, inode, newdentry, !!hardlink);
	newdentry = NULL;
out_dput2:
	dput(upper);
out_dput:
	dput(newdentry);
out_unlock:
	unlock_rename(workdir, upperdir);
out:
	if (!hardlink) {
		posix_acl_release(acl);
		posix_acl_release(default_acl);
	}
	return err;

out_cleanup:
	ovl_cleanup(wdir, newdentry);
	goto out_dput2;
}

static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
			      struct kstat *stat, const char *link,
			      struct dentry *hardlink)
{
	int err;
	const struct cred *old_cred;
	struct cred *override_cred;

	err = ovl_copy_up(dentry->d_parent);
	if (err)
		return err;

	old_cred = ovl_override_creds(dentry->d_sb);
	err = -ENOMEM;
	override_cred = prepare_creds();
	if (override_cred) {
		override_cred->fsuid = inode->i_uid;
		override_cred->fsgid = inode->i_gid;
		put_cred(override_creds(override_cred));
		put_cred(override_cred);

		if (!ovl_dentry_is_opaque(dentry))
			err = ovl_create_upper(dentry, inode, stat, link,
						hardlink);
		else
			err = ovl_create_over_whiteout(dentry, inode, stat,
							link, hardlink);
	}
	revert_creds(old_cred);
	if (!err) {
		struct inode *realinode = d_inode(ovl_dentry_upper(dentry));

		WARN_ON(inode->i_mode != realinode->i_mode);
		WARN_ON(!uid_eq(inode->i_uid, realinode->i_uid));
		WARN_ON(!gid_eq(inode->i_gid, realinode->i_gid));
	}
	return err;
}
Exemplo n.º 22
0
Arquivo: dir.c Projeto: Lyude/linux
static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
				    struct ovl_cattr *cattr)
{
	struct dentry *workdir = ovl_workdir(dentry);
	struct inode *wdir = workdir->d_inode;
	struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
	struct inode *udir = upperdir->d_inode;
	struct dentry *upper;
	struct dentry *newdentry;
	int err;
	struct posix_acl *acl, *default_acl;
	bool hardlink = !!cattr->hardlink;

	if (WARN_ON(!workdir))
		return -EROFS;

	if (!hardlink) {
		err = posix_acl_create(dentry->d_parent->d_inode,
				       &cattr->mode, &default_acl, &acl);
		if (err)
			return err;
	}

	err = ovl_lock_rename_workdir(workdir, upperdir);
	if (err)
		goto out;

	upper = lookup_one_len(dentry->d_name.name, upperdir,
			       dentry->d_name.len);
	err = PTR_ERR(upper);
	if (IS_ERR(upper))
		goto out_unlock;

	newdentry = ovl_create_temp(workdir, cattr);
	err = PTR_ERR(newdentry);
	if (IS_ERR(newdentry))
		goto out_dput;

	/*
	 * mode could have been mutilated due to umask (e.g. sgid directory)
	 */
	if (!hardlink &&
	    !S_ISLNK(cattr->mode) &&
	    newdentry->d_inode->i_mode != cattr->mode) {
		struct iattr attr = {
			.ia_valid = ATTR_MODE,
			.ia_mode = cattr->mode,
		};
		inode_lock(newdentry->d_inode);
		err = notify_change(newdentry, &attr, NULL);
		inode_unlock(newdentry->d_inode);
		if (err)
			goto out_cleanup;
	}
	if (!hardlink) {
		err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_ACCESS,
					acl);
		if (err)
			goto out_cleanup;

		err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_DEFAULT,
					default_acl);
		if (err)
			goto out_cleanup;
	}

	if (!hardlink && S_ISDIR(cattr->mode)) {
		err = ovl_set_opaque(dentry, newdentry);
		if (err)
			goto out_cleanup;

		err = ovl_do_rename(wdir, newdentry, udir, upper,
				    RENAME_EXCHANGE);
		if (err)
			goto out_cleanup;

		ovl_cleanup(wdir, upper);
	} else {
		err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
		if (err)
			goto out_cleanup;
	}
	err = ovl_instantiate(dentry, inode, newdentry, hardlink);
	if (err)
		goto out_cleanup;
out_dput:
	dput(upper);
out_unlock:
	unlock_rename(workdir, upperdir);
out:
	if (!hardlink) {
		posix_acl_release(acl);
		posix_acl_release(default_acl);
	}
	return err;

out_cleanup:
	ovl_cleanup(wdir, newdentry);
	dput(newdentry);
	goto out_dput;
}

static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
			      struct ovl_cattr *attr, bool origin)
{
	int err;
	const struct cred *old_cred;
	struct cred *override_cred;
	struct dentry *parent = dentry->d_parent;

	err = ovl_copy_up(parent);
	if (err)
		return err;

	old_cred = ovl_override_creds(dentry->d_sb);

	/*
	 * When linking a file with copy up origin into a new parent, mark the
	 * new parent dir "impure".
	 */
	if (origin) {
		err = ovl_set_impure(parent, ovl_dentry_upper(parent));
		if (err)
			goto out_revert_creds;
	}

	err = -ENOMEM;
	override_cred = prepare_creds();
	if (override_cred) {
		override_cred->fsuid = inode->i_uid;
		override_cred->fsgid = inode->i_gid;
		if (!attr->hardlink) {
			err = security_dentry_create_files_as(dentry,
					attr->mode, &dentry->d_name, old_cred,
					override_cred);
			if (err) {
				put_cred(override_cred);
				goto out_revert_creds;
			}
		}
		put_cred(override_creds(override_cred));
		put_cred(override_cred);

		if (!ovl_dentry_is_whiteout(dentry))
			err = ovl_create_upper(dentry, inode, attr);
		else
			err = ovl_create_over_whiteout(dentry, inode, attr);
	}
out_revert_creds:
	revert_creds(old_cred);
	return err;
}
Exemplo n.º 23
0
int ovl_getattr(const struct path *path, struct kstat *stat,
		u32 request_mask, unsigned int flags)
{
	struct dentry *dentry = path->dentry;
	enum ovl_path_type type;
	struct path realpath;
	const struct cred *old_cred;
	bool is_dir = S_ISDIR(dentry->d_inode->i_mode);
	int err;

	type = ovl_path_real(dentry, &realpath);
	old_cred = ovl_override_creds(dentry->d_sb);
	err = vfs_getattr(&realpath, stat, request_mask, flags);
	if (err)
		goto out;

	/*
	 * When all layers are on the same fs, all real inode number are
	 * unique, so we use the overlay st_dev, which is friendly to du -x.
	 *
	 * We also use st_ino of the copy up origin, if we know it.
	 * This guaranties constant st_dev/st_ino across copy up.
	 *
	 * If filesystem supports NFS export ops, this also guaranties
	 * persistent st_ino across mount cycle.
	 */
	if (ovl_same_sb(dentry->d_sb)) {
		if (OVL_TYPE_ORIGIN(type)) {
			struct kstat lowerstat;
			u32 lowermask = STATX_INO | (!is_dir ? STATX_NLINK : 0);

			ovl_path_lower(dentry, &realpath);
			err = vfs_getattr(&realpath, &lowerstat,
					  lowermask, flags);
			if (err)
				goto out;

			WARN_ON_ONCE(stat->dev != lowerstat.dev);
			/*
			 * Lower hardlinks may be broken on copy up to different
			 * upper files, so we cannot use the lower origin st_ino
			 * for those different files, even for the same fs case.
			 * With inodes index enabled, it is safe to use st_ino
			 * of an indexed hardlinked origin. The index validates
			 * that the upper hardlink is not broken.
			 */
			if (is_dir || lowerstat.nlink == 1 ||
			    ovl_test_flag(OVL_INDEX, d_inode(dentry)))
				stat->ino = lowerstat.ino;
		}
		stat->dev = dentry->d_sb->s_dev;
	} else if (is_dir) {
		/*
		 * If not all layers are on the same fs the pair {real st_ino;
		 * overlay st_dev} is not unique, so use the non persistent
		 * overlay st_ino.
		 *
		 * Always use the overlay st_dev for directories, so 'find
		 * -xdev' will scan the entire overlay mount and won't cross the
		 * overlay mount boundaries.
		 */
		stat->dev = dentry->d_sb->s_dev;
		stat->ino = dentry->d_inode->i_ino;
	}

	/*
	 * It's probably not worth it to count subdirs to get the
	 * correct link count.  nlink=1 seems to pacify 'find' and
	 * other utilities.
	 */
	if (is_dir && OVL_TYPE_MERGE(type))
		stat->nlink = 1;

	/*
	 * Return the overlay inode nlinks for indexed upper inodes.
	 * Overlay inode nlink counts the union of the upper hardlinks
	 * and non-covered lower hardlinks. It does not include the upper
	 * index hardlink.
	 */
	if (!is_dir && ovl_test_flag(OVL_INDEX, d_inode(dentry)))
		stat->nlink = dentry->d_inode->i_nlink;

out:
	revert_creds(old_cred);

	return err;
}