From cca189ef97d5f9fd3f52c75ec6e1ae916916cd08 Mon Sep 17 00:00:00 2001
From: "Nulo (he/him)" <86896666+catdevnull@users.noreply.github.com>
Date: Sat, 24 Sep 2022 13:04:14 +0000
Subject: [PATCH] Save files in local storage as umask (#21198)

Go creates temporary files as 600, but sometimes we want the group to be able to read them (for example,
for another user to back up the storage)

This PR applies the umask to the renamed tmp files in local storage.

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
---
 modules/storage/local.go       |  4 ++++
 modules/util/file_unix.go      | 28 ++++++++++++++++++++++++++
 modules/util/file_unix_test.go | 36 ++++++++++++++++++++++++++++++++++
 modules/util/file_windows.go   | 16 +++++++++++++++
 4 files changed, 84 insertions(+)
 create mode 100644 modules/util/file_unix.go
 create mode 100644 modules/util/file_unix_test.go
 create mode 100644 modules/util/file_windows.go

diff --git a/modules/storage/local.go b/modules/storage/local.go
index 701b0b1a9..5d5b06b64 100644
--- a/modules/storage/local.go
+++ b/modules/storage/local.go
@@ -102,6 +102,10 @@ func (l *LocalStorage) Save(path string, r io.Reader, size int64) (int64, error)
 	if err := util.Rename(tmp.Name(), p); err != nil {
 		return 0, err
 	}
+	// Golang's tmp file (os.CreateTemp) always have 0o600 mode, so we need to change the file to follow the umask (as what Create/MkDir does)
+	if err := util.ApplyUmask(p, os.ModePerm); err != nil {
+		return 0, err
+	}
 
 	tmpRemoved = true
 
diff --git a/modules/util/file_unix.go b/modules/util/file_unix.go
new file mode 100644
index 000000000..ec9d4ec16
--- /dev/null
+++ b/modules/util/file_unix.go
@@ -0,0 +1,28 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+//go:build !windows
+
+package util
+
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+var defaultUmask int
+
+func init() {
+	// at the moment, the umask could only be gotten by calling unix.Umask(newUmask)
+	// use 0o077 as temp new umask to reduce the risks if this umask is used anywhere else before the correct umask is recovered
+	tempUmask := 0o077
+	defaultUmask = unix.Umask(tempUmask)
+	unix.Umask(defaultUmask)
+}
+
+func ApplyUmask(f string, newMode os.FileMode) error {
+	mod := newMode & ^os.FileMode(defaultUmask)
+	return os.Chmod(f, mod)
+}
diff --git a/modules/util/file_unix_test.go b/modules/util/file_unix_test.go
new file mode 100644
index 000000000..41311aa13
--- /dev/null
+++ b/modules/util/file_unix_test.go
@@ -0,0 +1,36 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+//go:build !windows
+
+package util
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestApplyUmask(t *testing.T) {
+	f, err := os.CreateTemp(t.TempDir(), "test-filemode-")
+	assert.NoError(t, err)
+
+	err = os.Chmod(f.Name(), 0o777)
+	assert.NoError(t, err)
+	st, err := os.Stat(f.Name())
+	assert.NoError(t, err)
+	assert.EqualValues(t, 0o777, st.Mode().Perm()&0o777)
+
+	oldDefaultUmask := defaultUmask
+	defaultUmask = 0o037
+	defer func() {
+		defaultUmask = oldDefaultUmask
+	}()
+	err = ApplyUmask(f.Name(), os.ModePerm)
+	assert.NoError(t, err)
+	st, err = os.Stat(f.Name())
+	assert.NoError(t, err)
+	assert.EqualValues(t, 0o740, st.Mode().Perm()&0o777)
+}
diff --git a/modules/util/file_windows.go b/modules/util/file_windows.go
new file mode 100644
index 000000000..6ad3e88ba
--- /dev/null
+++ b/modules/util/file_windows.go
@@ -0,0 +1,16 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+//go:build windows
+
+package util
+
+import (
+	"os"
+)
+
+func ApplyUmask(f string, newMode os.FileMode) error {
+	// do nothing for Windows, because Windows doesn't use umask
+	return nil
+}