mirror of https://github.com/gohugoio/hugo
73 lines
4.1 KiB
Markdown
73 lines
4.1 KiB
Markdown
---
|
|
title: Security model
|
|
linkTitle: Security
|
|
description: A summary of Hugo's security model.
|
|
categories: [about]
|
|
keywords: [security,privacy]
|
|
menu:
|
|
docs:
|
|
parent: about
|
|
weight: 50
|
|
weight: 50
|
|
toc: true
|
|
aliases: [/about/security-model/]
|
|
---
|
|
|
|
## Runtime security
|
|
|
|
Hugo produces static output, so once built, the runtime is the browser (assuming the output is HTML) and any server (API) that you integrate with.
|
|
|
|
But when developing and building your site, the runtime is the `hugo` executable. Securing a runtime can be [a real challenge](https://blog.logrocket.com/how-to-protect-your-node-js-applications-from-malicious-dependencies-5f2e60ea08f9/).
|
|
|
|
**Hugo's main approach is that of sandboxing and a security policy with strict defaults:**
|
|
|
|
* Hugo has a virtual file system and only the main project (not third-party components) is allowed to mount directories or files outside the project root.
|
|
* User-defined components have read-only access to the filesystem.
|
|
* We shell out to some external binaries to support [Asciidoctor](/content-management/formats/#formats) and similar, but those binaries and their flags are predefined and disabled by default (see [Security Policy](#security-policy)). General functions to run arbitrary external OS commands have been [discussed](https://github.com/gohugoio/hugo/issues/796), but not implemented because of security concerns.
|
|
|
|
## Security policy
|
|
|
|
Hugo has a built-in security policy that restricts access to [os/exec](https://pkg.go.dev/os/exec), remote communication and similar.
|
|
|
|
The default configuration is listed below. Any build using features not in the allow list of the security policy will fail with a detailed message about what needs to be done. Most of these settings are allow lists (string or slice, [Regular Expressions](https://pkg.go.dev/regexp) or `none` which matches nothing).
|
|
|
|
{{< code-toggle config=security />}}
|
|
|
|
By default, Hugo permits the [`resources.GetRemote`] function to download files with media types corresponding to an internal allow list. To add media types to the allow list:
|
|
|
|
[`resources.GetRemote`]: /functions/resources/getremote
|
|
|
|
{{< code-toggle file=hugo >}}
|
|
[security.http]
|
|
mediaTypes = ['^image/avif$']
|
|
{{< /code-toggle >}}
|
|
|
|
Note that these and other configuration settings in Hugo can be overridden by the OS environment. For example, if you want to block all remote HTTP fetching of data:
|
|
|
|
```txt
|
|
HUGO_SECURITY_HTTP_URLS=none hugo
|
|
```
|
|
|
|
## Dependency security
|
|
|
|
Hugo is built as a static binary using [Go Modules](https://github.com/golang/go/wiki/Modules) to manage its dependencies. Go Modules have several safeguards, one of them being the `go.sum` file. This is a database of the expected cryptographic checksums of all of your dependencies, including transitive dependencies.
|
|
|
|
[Hugo Modules](/hugo-modules/) is a feature built on top of the functionality of Go Modules. Like Go Modules, a Hugo project using Hugo Modules will have a `go.sum` file. We recommend that you commit this file to your version control system. The Hugo build will fail if there is a checksum mismatch, which would be an indication of [dependency tampering](https://julienrenaux.fr/2019/12/20/github-actions-security-risk/).
|
|
|
|
## Web application security
|
|
|
|
These are the security threats as defined by [OWASP](https://en.wikipedia.org/wiki/OWASP).
|
|
|
|
For HTML output, this is the core security model:
|
|
|
|
<https://pkg.go.dev/html/template#hdr-Security_Model>
|
|
|
|
In short:
|
|
|
|
Template and configuration authors (you) are trusted, but the data you send in is not.
|
|
This is why you sometimes need to use the _safe_ functions, such as `safeHTML`, to avoid escaping of data you know is safe.
|
|
There is one exception to the above, as noted in the documentation: If you enable inline shortcodes, you also say that the shortcodes and data handling in content files are trusted, as those macros are treated as pure text.
|
|
It may be worth adding that Hugo is a static site generator with no concept of dynamic user input.
|
|
|
|
For content, the default Markdown renderer is [configured](/getting-started/configuration-markup) to remove or escape potentially unsafe content. This behavior can be reconfigured if you trust your content.
|