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Fix sanitizer config - multiple rules (#11133)

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In #9888, it was reported that my earlier pull request #9075 didn't quite function as expected. I was quite hopeful the `ValuesWithShadow()` worked as expected (and, I thought my testing showed it did) but I guess not. @zeripath proposed an alternative syntax which I like:

```ini
[markup.sanitizer.1]
ELEMENT=a
ALLOW_ATTR=target
REGEXP=something
[markup.sanitizer.2]
ELEMENT=a
ALLOW_ATTR=target
REGEXP=something
```

This was quite easy to adopt into the existing code. I've done so in a semi-backwards-compatible manner:

 - The value from `.Value()` is used for each element.
 - We parse `[markup.sanitizer]` and all `[markup.sanitizer.*]` sections and add them as rules.

This means that existing configs will load one rule (not all rules). It also means people can use string identifiers (`[markup.sanitiser.KaTeX]`) if they prefer, instead of numbered ones.

Co-authored-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>
This commit is contained in:
Alexander Scheel 2020-04-29 07:34:59 -04:00 committed by GitHub
parent 6b6f20b6d4
commit 1bf9e44bda
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GPG key ID: 4AEE18F83AFDEB23
4 changed files with 39 additions and 40 deletions
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6
custom/conf/app.ini.sample
View file

@ -976,8 +976,10 @@ SHOW_FOOTER_VERSION = true
; Show template execution time in the footer
SHOW_FOOTER_TEMPLATE_LOAD_TIME = true
[markup.sanitizer]
; The following keys can be used multiple times to define sanitation policy rules.
[markup.sanitizer.1]
; The following keys can appear once to define a sanitation policy rule.
; This section can appear multiple times by adding a unique alphanumeric suffix to define multiple rules.
; e.g., [markup.sanitizer.1] -> [markup.sanitizer.2] -> [markup.sanitizer.TeX]
;ELEMENT = span
;ALLOW_ATTR = class
;REGEXP = ^(info|warning|error)$

4
docs/content/doc/advanced/config-cheat-sheet.en-us.md
View file

@ -658,7 +658,7 @@ Two special environment variables are passed to the render command:
Gitea supports customizing the sanitization policy for rendered HTML. The example below will support KaTeX output from pandoc.
```ini
[markup.sanitizer]
[markup.sanitizer.TeX]
; Pandoc renders TeX segments as <span>s with the "math" class, optionally
; with "inline" or "display" classes depending on context.
ELEMENT = span
@ -670,7 +670,7 @@ REGEXP = ^\s*((math(\s+|$)|inline(\s+|$)|display(\s+|$)))+
- `ALLOW_ATTR`: The attribute this policy allows. Must be non-empty.
- `REGEXP`: A regex to match the contents of the attribute against. Must be present but may be empty for unconditional whitelisting of this attribute.
You may redefine `ELEMENT`, `ALLOW_ATTR`, and `REGEXP` multiple times; each time all three are defined is a single policy entry.
Multiple sanitisation rules can be defined by adding unique subsections, e.g. `[markup.sanitizer.TeX-2]`.
## Time (`time`)

9
docs/content/doc/advanced/external-renderers.en-us.md
View file

@ -73,7 +73,7 @@ IS_INPUT_FILE = false
If your external markup relies on additional classes and attributes on the generated HTML elements, you might need to enable custom sanitizer policies. Gitea uses the [`bluemonday`](https://godoc.org/github.com/microcosm-cc/bluemonday) package as our HTML sanitizier. The example below will support [KaTeX](https://katex.org/) output from [`pandoc`](https://pandoc.org/).
```ini
[markup.sanitizer]
[markup.sanitizer.TeX]
; Pandoc renders TeX segments as <span>s with the "math" class, optionally
; with "inline" or "display" classes depending on context.
ELEMENT = span
@ -86,6 +86,11 @@ FILE_EXTENSIONS = .md,.markdown
RENDER_COMMAND = pandoc -f markdown -t html --katex
```
You may redefine `ELEMENT`, `ALLOW_ATTR`, and `REGEXP` multiple times; each time all three are defined is a single policy entry. All three must be defined, but `REGEXP` may be blank to allow unconditional whitelisting of that attribute.
You must define `ELEMENT`, `ALLOW_ATTR`, and `REGEXP` in each section.
To define multiple entries, add a unique alphanumeric suffix (e.g., `[markup.sanitizer.1]` and `[markup.sanitizer.something]`).
Once your configuration changes have been made, restart Gitea to have changes take effect.
**Note**: Prior to Gitea 1.12 there was a single `markup.sanitiser` section with keys that were redefined for multiple rules, however,
there were significant problems with this method of configuration necessitating configuration through multiple sections.

60
modules/setting/markup.go
View file

@ -44,7 +44,7 @@ func newMarkup() {
continue
}
if name == "sanitizer" {
if name == "sanitizer" || strings.HasPrefix(name, "sanitizer.") {
newMarkupSanitizer(name, sec)
} else {
newMarkupRenderer(name, sec)
@ -67,44 +67,36 @@ func newMarkupSanitizer(name string, sec *ini.Section) {
return
}
elements := sec.Key("ELEMENT").ValueWithShadows()
allowAttrs := sec.Key("ALLOW_ATTR").ValueWithShadows()
regexps := sec.Key("REGEXP").ValueWithShadows()
elements := sec.Key("ELEMENT").Value()
allowAttrs := sec.Key("ALLOW_ATTR").Value()
regexpStr := sec.Key("REGEXP").Value()
if len(elements) != len(allowAttrs) ||
len(elements) != len(regexps) {
log.Error("All three keys in markup.%s (ELEMENT, ALLOW_ATTR, REGEXP) must be defined the same number of times! Got %d, %d, and %d respectively.", name, len(elements), len(allowAttrs), len(regexps))
if regexpStr == "" {
rule := MarkupSanitizerRule{
Element: elements,
AllowAttr: allowAttrs,
Regexp: nil,
}
ExternalSanitizerRules = append(ExternalSanitizerRules, rule)
return
}
ExternalSanitizerRules = make([]MarkupSanitizerRule, 0, len(elements))
for index, pattern := range regexps {
if pattern == "" {
rule := MarkupSanitizerRule{
Element: elements[index],
AllowAttr: allowAttrs[index],
Regexp: nil,
}
ExternalSanitizerRules = append(ExternalSanitizerRules, rule)
continue
}
// Validate when parsing the config that this is a valid regular
// expression. Then we can use regexp.MustCompile(...) later.
compiled, err := regexp.Compile(pattern)
if err != nil {
log.Error("In module.%s: REGEXP at definition %d failed to compile: %v", name, index+1, err)
continue
}
rule := MarkupSanitizerRule{
Element: elements[index],
AllowAttr: allowAttrs[index],
Regexp: compiled,
}
ExternalSanitizerRules = append(ExternalSanitizerRules, rule)
// Validate when parsing the config that this is a valid regular
// expression. Then we can use regexp.MustCompile(...) later.
compiled, err := regexp.Compile(regexpStr)
if err != nil {
log.Error("In module.%s: REGEXP (%s) at definition %d failed to compile: %v", regexpStr, name, err)
return
}
rule := MarkupSanitizerRule{
Element: elements,
AllowAttr: allowAttrs,
Regexp: compiled,
}
ExternalSanitizerRules = append(ExternalSanitizerRules, rule)
}
func newMarkupRenderer(name string, sec *ini.Section) {