hugo/config/security/whitelist.go
Bjørn Erik Pedersen f4389e48ce
Add some basic security policies with sensible defaults
This ommmit contains some security hardening measures for the Hugo build runtime.

There are some rarely used features in Hugo that would be good to have disabled by default. One example would be the "external helpers".

For `asciidoctor` and some others we use Go's `os/exec` package to start a new process.

These are a predefined set of binary names, all loaded from `PATH` and with a predefined set of arguments. Still, if you don't use `asciidoctor` in your project, you might as well have it turned off.

You can configure your own in the new `security` configuration section, but the defaults are configured to create a minimal amount of site breakage. And if that do happen, you will get clear instructions in the loa about what to do.

The default configuration is listed below. Note that almost all of these options are regular expression _whitelists_ (a string or a slice); the value `none` will block all.

```toml
[security]
  enableInlineShortcodes = false
  [security.exec]
    allow = ['^dart-sass-embedded$', '^go$', '^npx$', '^postcss$']
    osEnv = ['(?i)^(PATH|PATHEXT|APPDATA|TMP|TEMP|TERM)$']

  [security.funcs]
    getenv = ['^HUGO_']

  [security.http]
    methods = ['(?i)GET|POST']
    urls = ['.*']
```
2021-12-16 09:40:22 +01:00

103 lines
2.2 KiB
Go

// Copyright 2021 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package security
import (
"encoding/json"
"fmt"
"regexp"
"strings"
)
const (
acceptNoneKeyword = "none"
)
// Whitelist holds a whitelist.
type Whitelist struct {
acceptNone bool
patterns []*regexp.Regexp
// Store this for debugging/error reporting
patternsStrings []string
}
func (w Whitelist) MarshalJSON() ([]byte, error) {
if w.acceptNone {
return json.Marshal(acceptNoneKeyword)
}
return json.Marshal(w.patternsStrings)
}
// NewWhitelist creates a new Whitelist from zero or more patterns.
// An empty patterns list or a pattern with the value 'none' will create
// a whitelist that will Accept noone.
func NewWhitelist(patterns ...string) Whitelist {
if len(patterns) == 0 {
return Whitelist{acceptNone: true}
}
var acceptSome bool
var patternsStrings []string
for _, p := range patterns {
if p == acceptNoneKeyword {
acceptSome = false
break
}
if ps := strings.TrimSpace(p); ps != "" {
acceptSome = true
patternsStrings = append(patternsStrings, ps)
}
}
if !acceptSome {
return Whitelist{
acceptNone: true,
}
}
var patternsr []*regexp.Regexp
for i := 0; i < len(patterns); i++ {
p := strings.TrimSpace(patterns[i])
if p == "" {
continue
}
patternsr = append(patternsr, regexp.MustCompile(p))
}
return Whitelist{patterns: patternsr, patternsStrings: patternsStrings}
}
// Accepted reports whether name is whitelisted.
func (w Whitelist) Accept(name string) bool {
if w.acceptNone {
return false
}
for _, p := range w.patterns {
if p.MatchString(name) {
return true
}
}
return false
}
func (w Whitelist) String() string {
return fmt.Sprint(w.patternsStrings)
}