Merge tag 'ovl-update-4.20' of git://git.kernel.org/pub/scm/linux/ker…

…nel/git/mszeredi/vfs

Pull overlayfs updates from Miklos Szeredi:
 "A mix of fixes and cleanups"

* tag 'ovl-update-4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: automatically enable redirect_dir on metacopy=on
  ovl: check whiteout in ovl_create_over_whiteout()
  ovl: using posix_acl_xattr_size() to get size instead of posix_acl_to_xattr()
  ovl: abstract ovl_inode lock with a helper
  ovl: remove the 'locked' argument of ovl_nlink_{start,end}
  ovl: relax requirement for non null uuid of lower fs
  ovl: fold copy-up helpers into callers
  ovl: untangle copy up call chain
  ovl: relax permission checking on underlying layers
  ovl: fix recursive oi->lock in ovl_link()
  vfs: fix FIGETBSZ ioctl on an overlayfs file
  ovl: clean up error handling in ovl_get_tmpfile()
  ovl: fix error handling in ovl_verify_set_fh()

Documentation/filesystems/overlayfs.txt

@@ -286,6 +286,12 @@ pointed by REDIRECT. This should not be possible on local system as setting
 "trusted." xattrs will require CAP_SYS_ADMIN. But it should be possible
 for untrusted layers like from a pen drive.
 
+Note: redirect_dir={off|nofollow|follow(*)} conflicts with metacopy=on, and
+results in an error.
+
+(*) redirect_dir=follow only conflicts with metacopy=on if upperdir=... is
+given.
+
 Sharing and copying layers
 --------------------------
 

fs/ioctl.c

@@ -669,6 +669,9 @@ int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
 		return ioctl_fiemap(filp, arg);
 
 	case FIGETBSZ:
+		/* anon_bdev filesystems may not have a block size */
+		if (!inode->i_sb->s_blocksize)
+			return -EINVAL;
 		return put_user(inode->i_sb->s_blocksize, argp);
 
 	case FICLONE:

fs/overlayfs/copy_up.c

@@ -395,7 +395,6 @@ struct ovl_copy_up_ctx {
 	struct dentry *destdir;
 	struct qstr destname;
 	struct dentry *workdir;
-	bool tmpfile;
 	bool origin;
 	bool indexed;
 	bool metacopy;
@@ -440,63 +439,6 @@ static int ovl_link_up(struct ovl_copy_up_ctx *c)
 	return err;
 }
 
-static int ovl_install_temp(struct ovl_copy_up_ctx *c, struct dentry *temp,
-			    struct dentry **newdentry)
-{
-	int err;
-	struct dentry *upper;
-	struct inode *udir = d_inode(c->destdir);
-
-	upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
-	if (IS_ERR(upper))
-		return PTR_ERR(upper);
-
-	if (c->tmpfile)
-		err = ovl_do_link(temp, udir, upper);
-	else
-		err = ovl_do_rename(d_inode(c->workdir), temp, udir, upper, 0);
-
-	if (!err)
-		*newdentry = dget(c->tmpfile ? upper : temp);
-	dput(upper);
-
-	return err;
-}
-
-static struct dentry *ovl_get_tmpfile(struct ovl_copy_up_ctx *c)
-{
-	int err;
-	struct dentry *temp;
-	const struct cred *old_creds = NULL;
-	struct cred *new_creds = NULL;
-	struct ovl_cattr cattr = {
-		/* Can't properly set mode on creation because of the umask */
-		.mode = c->stat.mode & S_IFMT,
-		.rdev = c->stat.rdev,
-		.link = c->link
-	};
-
-	err = security_inode_copy_up(c->dentry, &new_creds);
-	temp = ERR_PTR(err);
-	if (err < 0)
-		goto out;
-
-	if (new_creds)
-		old_creds = override_creds(new_creds);
-
-	if (c->tmpfile)
-		temp = ovl_do_tmpfile(c->workdir, c->stat.mode);
-	else
-		temp = ovl_create_temp(c->workdir, &cattr);
-out:
-	if (new_creds) {
-		revert_creds(old_creds);
-		put_cred(new_creds);
-	}
-
-	return temp;
-}
-
 static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
 {
 	int err;
@@ -548,51 +490,148 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
 	return err;
 }
 
-static int ovl_copy_up_locked(struct ovl_copy_up_ctx *c)
+struct ovl_cu_creds {
+	const struct cred *old;
+	struct cred *new;
+};
+
+static int ovl_prep_cu_creds(struct dentry *dentry, struct ovl_cu_creds *cc)
+{
+	int err;
+
+	cc->old = cc->new = NULL;
+	err = security_inode_copy_up(dentry, &cc->new);
+	if (err < 0)
+		return err;
+
+	if (cc->new)
+		cc->old = override_creds(cc->new);
+
+	return 0;
+}
+
+static void ovl_revert_cu_creds(struct ovl_cu_creds *cc)
+{
+	if (cc->new) {
+		revert_creds(cc->old);
+		put_cred(cc->new);
+	}
+}
+
+/*
+ * Copyup using workdir to prepare temp file.  Used when copying up directories,
+ * special files or when upper fs doesn't support O_TMPFILE.
+ */
+static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
 {
-	struct inode *udir = c->destdir->d_inode;
 	struct inode *inode;
-	struct dentry *newdentry = NULL;
-	struct dentry *temp;
+	struct inode *udir = d_inode(c->destdir), *wdir = d_inode(c->workdir);
+	struct dentry *temp, *upper;
+	struct ovl_cu_creds cc;
 	int err;
+	struct ovl_cattr cattr = {
+		/* Can't properly set mode on creation because of the umask */
+		.mode = c->stat.mode & S_IFMT,
+		.rdev = c->stat.rdev,
+		.link = c->link
+	};
 
-	temp = ovl_get_tmpfile(c);
+	err = ovl_lock_rename_workdir(c->workdir, c->destdir);
+	if (err)
+		return err;
+
+	err = ovl_prep_cu_creds(c->dentry, &cc);
+	if (err)
+		goto unlock;
+
+	temp = ovl_create_temp(c->workdir, &cattr);
+	ovl_revert_cu_creds(&cc);
+
+	err = PTR_ERR(temp);
 	if (IS_ERR(temp))
-		return PTR_ERR(temp);
+		goto unlock;
 
 	err = ovl_copy_up_inode(c, temp);
 	if (err)
-		goto out;
+		goto cleanup;
 
 	if (S_ISDIR(c->stat.mode) && c->indexed) {
 		err = ovl_create_index(c->dentry, c->lowerpath.dentry, temp);
 		if (err)
-			goto out;
+			goto cleanup;
 	}
 
-	if (c->tmpfile) {
-		inode_lock_nested(udir, I_MUTEX_PARENT);
-		err = ovl_install_temp(c, temp, &newdentry);
-		inode_unlock(udir);
-	} else {
-		err = ovl_install_temp(c, temp, &newdentry);
-	}
+	upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
+	err = PTR_ERR(upper);
+	if (IS_ERR(upper))
+		goto cleanup;
+
+	err = ovl_do_rename(wdir, temp, udir, upper, 0);
+	dput(upper);
 	if (err)
-		goto out;
+		goto cleanup;
 
 	if (!c->metacopy)
 		ovl_set_upperdata(d_inode(c->dentry));
 	inode = d_inode(c->dentry);
-	ovl_inode_update(inode, newdentry);
+	ovl_inode_update(inode, temp);
 	if (S_ISDIR(inode->i_mode))
 		ovl_set_flag(OVL_WHITEOUTS, inode);
+unlock:
+	unlock_rename(c->workdir, c->destdir);
 
-out:
-	if (err && !c->tmpfile)
-		ovl_cleanup(d_inode(c->workdir), temp);
-	dput(temp);
 	return err;
 
+cleanup:
+	ovl_cleanup(wdir, temp);
+	dput(temp);
+	goto unlock;
+}
+
+/* Copyup using O_TMPFILE which does not require cross dir locking */
+static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
+{
+	struct inode *udir = d_inode(c->destdir);
+	struct dentry *temp, *upper;
+	struct ovl_cu_creds cc;
+	int err;
+
+	err = ovl_prep_cu_creds(c->dentry, &cc);
+	if (err)
+		return err;
+
+	temp = ovl_do_tmpfile(c->workdir, c->stat.mode);
+	ovl_revert_cu_creds(&cc);
+
+	if (IS_ERR(temp))
+		return PTR_ERR(temp);
+
+	err = ovl_copy_up_inode(c, temp);
+	if (err)
+		goto out_dput;
+
+	inode_lock_nested(udir, I_MUTEX_PARENT);
+
+	upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
+	err = PTR_ERR(upper);
+	if (!IS_ERR(upper)) {
+		err = ovl_do_link(temp, udir, upper);
+		dput(upper);
+	}
+	inode_unlock(udir);
+
+	if (err)
+		goto out_dput;
+
+	if (!c->metacopy)
+		ovl_set_upperdata(d_inode(c->dentry));
+	ovl_inode_update(d_inode(c->dentry), temp);
+
+	return 0;
+
+out_dput:
+	dput(temp);
+	return err;
 }
 
 /*
@@ -646,18 +685,10 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
 	}
 
 	/* Should we copyup with O_TMPFILE or with workdir? */
-	if (S_ISREG(c->stat.mode) && ofs->tmpfile) {
-		c->tmpfile = true;
-		err = ovl_copy_up_locked(c);
-	} else {
-		err = ovl_lock_rename_workdir(c->workdir, c->destdir);
-		if (!err) {
-			err = ovl_copy_up_locked(c);
-			unlock_rename(c->workdir, c->destdir);
-		}
-	}
-
-
+	if (S_ISREG(c->stat.mode) && ofs->tmpfile)
+		err = ovl_copy_up_tmpfile(c);
+	else
+		err = ovl_copy_up_workdir(c);
 	if (err)
 		goto out;