Changeset - 5746cc3b3fa5
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Mads Kiilerich - 7 years ago 2018-10-21 17:44:06
mads@kiilerich.com
Grafted from: 35cfc37c3c9b
lib: use bleach to sanitize HTML generated from markdown - fix XSS issue when repo front page shows README.md

Reported by Bob Hogg <wombat@rwhogg.site> .
2 files changed with 21 insertions and 7 deletions:
kallithea/lib/markup_renderer.py
20
7
setup.py
1
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kallithea/lib/markup_renderer.py
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@@ -31,6 +31,7 @@ import logging
 
import traceback
 

			




	
	
	
		
 
import markdown as markdown_mod

			




	
	
	
		
 
import bleach

			




	
	
	
		
 

			




	
	
	
		
 
from kallithea.lib.utils2 import safe_unicode, MENTIONS_REGEX

			




	
	
	
		
 

			




	
	
		
 
@@ -142,28 +143,40 @@ class MarkupRenderer(object):

			




	
	
	
		
 
    @classmethod

			




	
	
	
		
 
    def markdown(cls, source, safe=True, flavored=False):

			




	
	
	
		
 
        """

			




	
	
	
		
 
        Convert Markdown (possibly GitHub Flavored) to HTML, possibly

			




	
	
	
		
 
        Convert Markdown (possibly GitHub Flavored) to XSS safe HTML, possibly

			




	
	
	
		
 
        with "safe" fall-back to plaintext.

			




	
	
	
		
 

			




	
	
	
		
 
        >>> MarkupRenderer.markdown('''<img id="a" style="margin-top:-1000px;color:red" src="http://example.com/test.jpg">''')

			




	
	
	
		
 
        u'<p><img id="a" style="margin-top:-1000px;color:red" src="http://example.com/test.jpg"></p>'

			




	
	
	
		
 
        u'<p><img id="a" src="http://example.com/test.jpg" style="color: red;"></p>'

			




	
	
	
		
 
        >>> MarkupRenderer.markdown('''<img class="c d" src="file://localhost/test.jpg">''')

			




	
	
	
		
 
        u'<p><img class="c d" src="file://localhost/test.jpg"></p>'

			




	
	
	
		
 
        u'<p><img class="c d"></p>'

			




	
	
	
		
 
        >>> MarkupRenderer.markdown('''<a href="foo">foo</a>''')

			




	
	
	
		
 
        u'<p><a href="foo">foo</a></p>'

			




	
	
	
		
 
        >>> MarkupRenderer.markdown('''<script>alert(1)</script>''')

			




	
	
	
		
 
        u'<script>alert(1)</script>'

			




	
	
	
		
 
        u'&lt;script&gt;alert(1)&lt;/script&gt;'

			




	
	
	
		
 
        >>> MarkupRenderer.markdown('''<div onclick="alert(2)">yo</div>''')

			




	
	
	
		
 
        u'<div onclick="alert(2)">yo</div>'

			




	
	
	
		
 
        u'<div>yo</div>'

			




	
	
	
		
 
        >>> MarkupRenderer.markdown('''<a href="javascript:alert(3)">yo</a>''')

			




	
	
	
		
 
        u'<p><a href="javascript:alert(3)">yo</a></p>'

			




	
	
	
		
 
        u'<p><a>yo</a></p>'

			




	
	
	
		
 
        """

			




	
	
	
		
 
        source = safe_unicode(source)

			




	
	
	
		
 
        try:

			




	
	
	
		
 
            if flavored:

			




	
	
	
		
 
                source = cls._flavored_markdown(source)

			




	
	
	
		
 
            markdown_html = markdown_mod.markdown(source, ['codehilite', 'extra'])

			




	
	
	
		
 
            return markdown_html

			




	
	
	
		
 
            # Allow most HTML, while preventing XSS issues:

			




	
	
	
		
 
            # no <script> tags, no onclick attributes, no javascript

			




	
	
	
		
 
            # "protocol", and also limit styling to prevent defacing.

			




	
	
	
		
 
            return bleach.clean(markdown_html,

			




	
	
	
		
 
                tags=['a', 'abbr', 'b', 'blockquote', 'br', 'code', 'dd',

			




	
	
	
		
 
                      'div', 'dl', 'dt', 'em', 'h1', 'h2', 'h3', 'h4', 'h5',

			




	
	
	
		
 
                      'h6', 'hr', 'i', 'img', 'li', 'ol', 'p', 'pre', 'span',

			




	
	
	
		
 
                      'strong', 'sub', 'sup', 'table', 'tbody', 'td', 'th',

			




	
	
	
		
 
                      'thead', 'tr', 'ul'],

			




	
	
	
		
 
                attributes=['class', 'id', 'style', 'label', 'title', 'alt', 'href', 'src'],

			




	
	
	
		
 
                styles=['color'],

			




	
	
	
		
 
                protocols=['http', 'https', 'mailto'],

			




	
	
	
		
 
                )

			




	
	
	
		
 
        except Exception:

			




	
	
	
		
 
            log.error(traceback.format_exc())

			




	
	
	
		
 
            if safe:

			




        

    


    
    

    

        

                

                    setup.py
                

                

                  
                      
                        

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@@ -57,6 +57,7 @@ requirements = [

			




	
	
	
		
 
    "Routes==1.13",

			




	
	
	
		
 
    "dulwich>=0.9.9,<=0.9.9",

			




	
	
	
		
 
    "mercurial>=2.9,<4.3",

			




	
	
	
		
 
    "bleach >= 3.0, < 3.1",

			




	
	
	
		
 
]

			




	
	
	
		
 

			




	
	
	
		
 
if sys.version_info < (2, 7):

			




        

    



    


    



    



      

      





    
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