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* Support custom sanitization policy Allowing the gitea administrator to configure sanitization policy allows them to couple external renders and custom templates to support more markup. In particular, the `pandoc` renderer allows generating KaTeX annotations, wrapping them in `<span>` elements with class `math` and either `inline` or `display` (depending on whether or not inline or block mode was requested). This iteration gives the administrator whitelisting powers; carefully crafted regexes will thus let through only the desired attributes necessary to support their custom markup. Resolves: #9054 Signed-off-by: Alexander Scheel <alexander.m.scheel@gmail.com> * Document new sanitization configuration - Adds basic documentation to app.ini.sample, - Adds an example to the Configuration Cheat Sheet, and - Adds extended information to External Renderers section. Signed-off-by: Alexander Scheel <alexander.m.scheel@gmail.com> * Drop extraneous length check in newMarkupSanitizer(...) Signed-off-by: Alexander Scheel <alexander.m.scheel@gmail.com> * Fix plural ELEMENT and ALLOW_ATTR in docs These were left over from their initial names. Make them singular to conform with the current expectations. Signed-off-by: Alexander Scheel <alexander.m.scheel@gmail.com>
142 lines
3.8 KiB
Go
142 lines
3.8 KiB
Go
// Copyright 2019 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package setting
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import (
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"regexp"
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"strings"
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"code.gitea.io/gitea/modules/log"
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"gopkg.in/ini.v1"
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)
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// ExternalMarkupParsers represents the external markup parsers
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var (
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ExternalMarkupParsers []MarkupParser
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ExternalSanitizerRules []MarkupSanitizerRule
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)
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// MarkupParser defines the external parser configured in ini
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type MarkupParser struct {
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Enabled bool
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MarkupName string
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Command string
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FileExtensions []string
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IsInputFile bool
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}
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// MarkupSanitizerRule defines the policy for whitelisting attributes on
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// certain elements.
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type MarkupSanitizerRule struct {
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Element string
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AllowAttr string
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Regexp *regexp.Regexp
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}
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func newMarkup() {
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for _, sec := range Cfg.Section("markup").ChildSections() {
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name := strings.TrimPrefix(sec.Name(), "markup.")
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if name == "" {
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log.Warn("name is empty, markup " + sec.Name() + "ignored")
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continue
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}
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if name == "sanitizer" {
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newMarkupSanitizer(name, sec)
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} else {
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newMarkupRenderer(name, sec)
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}
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}
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}
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func newMarkupSanitizer(name string, sec *ini.Section) {
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haveElement := sec.HasKey("ELEMENT")
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haveAttr := sec.HasKey("ALLOW_ATTR")
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haveRegexp := sec.HasKey("REGEXP")
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if !haveElement && !haveAttr && !haveRegexp {
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log.Warn("Skipping empty section: markup.%s.", name)
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return
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}
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if !haveElement || !haveAttr || !haveRegexp {
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log.Error("Missing required keys from markup.%s. Must have all three of ELEMENT, ALLOW_ATTR, and REGEXP defined!", name)
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return
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}
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elements := sec.Key("ELEMENT").ValueWithShadows()
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allowAttrs := sec.Key("ALLOW_ATTR").ValueWithShadows()
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regexps := sec.Key("REGEXP").ValueWithShadows()
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if len(elements) != len(allowAttrs) ||
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len(elements) != len(regexps) {
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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))
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return
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}
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ExternalSanitizerRules = make([]MarkupSanitizerRule, 0, len(elements))
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for index, pattern := range regexps {
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if pattern == "" {
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rule := MarkupSanitizerRule{
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Element: elements[index],
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AllowAttr: allowAttrs[index],
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Regexp: nil,
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}
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ExternalSanitizerRules = append(ExternalSanitizerRules, rule)
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continue
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}
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// Validate when parsing the config that this is a valid regular
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// expression. Then we can use regexp.MustCompile(...) later.
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compiled, err := regexp.Compile(pattern)
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if err != nil {
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log.Error("In module.%s: REGEXP at definition %d failed to compile: %v", name, index+1, err)
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continue
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}
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rule := MarkupSanitizerRule{
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Element: elements[index],
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AllowAttr: allowAttrs[index],
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Regexp: compiled,
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}
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ExternalSanitizerRules = append(ExternalSanitizerRules, rule)
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}
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}
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func newMarkupRenderer(name string, sec *ini.Section) {
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extensionReg := regexp.MustCompile(`\.\w`)
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extensions := sec.Key("FILE_EXTENSIONS").Strings(",")
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var exts = make([]string, 0, len(extensions))
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for _, extension := range extensions {
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if !extensionReg.MatchString(extension) {
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log.Warn(sec.Name() + " file extension " + extension + " is invalid. Extension ignored")
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} else {
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exts = append(exts, extension)
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}
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}
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if len(exts) == 0 {
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log.Warn(sec.Name() + " file extension is empty, markup " + name + " ignored")
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return
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}
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command := sec.Key("RENDER_COMMAND").MustString("")
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if command == "" {
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log.Warn(" RENDER_COMMAND is empty, markup " + name + " ignored")
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return
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}
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ExternalMarkupParsers = append(ExternalMarkupParsers, MarkupParser{
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Enabled: sec.Key("ENABLED").MustBool(false),
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MarkupName: name,
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FileExtensions: exts,
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Command: command,
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IsInputFile: sec.Key("IS_INPUT_FILE").MustBool(false),
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})
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}
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