/
sanitizer.py
296 lines (260 loc) · 17.3 KB
/
sanitizer.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
from __future__ import absolute_import, division, unicode_literals
import re
from xml.sax.saxutils import escape, unescape
from six.moves import urllib_parse as urlparse
from .tokenizer import HTMLTokenizer
from .constants import tokenTypes
content_type_rgx = re.compile(r'''
^
# Match a content type <application>/<type>
(?P<content_type>[-a-zA-Z0-9.]+/[-a-zA-Z0-9.]+)
# Match any character set and encoding
(?:(?:;charset=(?:[-a-zA-Z0-9]+)(?:;(?:base64))?)
|(?:;(?:base64))?(?:;charset=(?:[-a-zA-Z0-9]+))?)
# Assume the rest is data
,.*
$
''',
re.VERBOSE)
class HTMLSanitizerMixin(object):
""" sanitization of XHTML+MathML+SVG and of inline style attributes."""
acceptable_elements = ['a', 'abbr', 'acronym', 'address', 'area',
'article', 'aside', 'audio', 'b', 'big', 'blockquote', 'br', 'button',
'canvas', 'caption', 'center', 'cite', 'code', 'col', 'colgroup',
'command', 'datagrid', 'datalist', 'dd', 'del', 'details', 'dfn',
'dialog', 'dir', 'div', 'dl', 'dt', 'em', 'event-source', 'fieldset',
'figcaption', 'figure', 'footer', 'font', 'form', 'header', 'h1',
'h2', 'h3', 'h4', 'h5', 'h6', 'hr', 'i', 'img', 'input', 'ins',
'keygen', 'kbd', 'label', 'legend', 'li', 'm', 'map', 'menu', 'meter',
'multicol', 'nav', 'nextid', 'ol', 'output', 'optgroup', 'option',
'p', 'pre', 'progress', 'q', 's', 'samp', 'section', 'select',
'small', 'sound', 'source', 'spacer', 'span', 'strike', 'strong',
'sub', 'sup', 'table', 'tbody', 'td', 'textarea', 'time', 'tfoot',
'th', 'thead', 'tr', 'tt', 'u', 'ul', 'var', 'video']
mathml_elements = ['maction', 'math', 'merror', 'mfrac', 'mi',
'mmultiscripts', 'mn', 'mo', 'mover', 'mpadded', 'mphantom',
'mprescripts', 'mroot', 'mrow', 'mspace', 'msqrt', 'mstyle', 'msub',
'msubsup', 'msup', 'mtable', 'mtd', 'mtext', 'mtr', 'munder',
'munderover', 'none']
svg_elements = ['a', 'animate', 'animateColor', 'animateMotion',
'animateTransform', 'clipPath', 'circle', 'defs', 'desc', 'ellipse',
'font-face', 'font-face-name', 'font-face-src', 'g', 'glyph', 'hkern',
'linearGradient', 'line', 'marker', 'metadata', 'missing-glyph',
'mpath', 'path', 'polygon', 'polyline', 'radialGradient', 'rect',
'set', 'stop', 'svg', 'switch', 'text', 'title', 'tspan', 'use']
acceptable_attributes = ['abbr', 'accept', 'accept-charset', 'accesskey',
'action', 'align', 'alt', 'autocomplete', 'autofocus', 'axis',
'background', 'balance', 'bgcolor', 'bgproperties', 'border',
'bordercolor', 'bordercolordark', 'bordercolorlight', 'bottompadding',
'cellpadding', 'cellspacing', 'ch', 'challenge', 'char', 'charoff',
'choff', 'charset', 'checked', 'cite', 'class', 'clear', 'color',
'cols', 'colspan', 'compact', 'contenteditable', 'controls', 'coords',
'data', 'datafld', 'datapagesize', 'datasrc', 'datetime', 'default',
'delay', 'dir', 'disabled', 'draggable', 'dynsrc', 'enctype', 'end',
'face', 'for', 'form', 'frame', 'galleryimg', 'gutter', 'headers',
'height', 'hidefocus', 'hidden', 'high', 'href', 'hreflang', 'hspace',
'icon', 'id', 'inputmode', 'ismap', 'keytype', 'label', 'leftspacing',
'lang', 'list', 'longdesc', 'loop', 'loopcount', 'loopend',
'loopstart', 'low', 'lowsrc', 'max', 'maxlength', 'media', 'method',
'min', 'multiple', 'name', 'nohref', 'noshade', 'nowrap', 'open',
'optimum', 'pattern', 'ping', 'point-size', 'poster', 'pqg', 'preload',
'prompt', 'radiogroup', 'readonly', 'rel', 'repeat-max', 'repeat-min',
'replace', 'required', 'rev', 'rightspacing', 'rows', 'rowspan',
'rules', 'scope', 'selected', 'shape', 'size', 'span', 'src', 'start',
'step', 'style', 'summary', 'suppress', 'tabindex', 'target',
'template', 'title', 'toppadding', 'type', 'unselectable', 'usemap',
'urn', 'valign', 'value', 'variable', 'volume', 'vspace', 'vrml',
'width', 'wrap', 'xml:lang']
mathml_attributes = ['actiontype', 'align', 'columnalign', 'columnalign',
'columnalign', 'columnlines', 'columnspacing', 'columnspan', 'depth',
'display', 'displaystyle', 'equalcolumns', 'equalrows', 'fence',
'fontstyle', 'fontweight', 'frame', 'height', 'linethickness', 'lspace',
'mathbackground', 'mathcolor', 'mathvariant', 'mathvariant', 'maxsize',
'minsize', 'other', 'rowalign', 'rowalign', 'rowalign', 'rowlines',
'rowspacing', 'rowspan', 'rspace', 'scriptlevel', 'selection',
'separator', 'stretchy', 'width', 'width', 'xlink:href', 'xlink:show',
'xlink:type', 'xmlns', 'xmlns:xlink']
svg_attributes = ['accent-height', 'accumulate', 'additive', 'alphabetic',
'arabic-form', 'ascent', 'attributeName', 'attributeType',
'baseProfile', 'bbox', 'begin', 'by', 'calcMode', 'cap-height',
'class', 'clip-path', 'color', 'color-rendering', 'content', 'cx',
'cy', 'd', 'dx', 'dy', 'descent', 'display', 'dur', 'end', 'fill',
'fill-opacity', 'fill-rule', 'font-family', 'font-size',
'font-stretch', 'font-style', 'font-variant', 'font-weight', 'from',
'fx', 'fy', 'g1', 'g2', 'glyph-name', 'gradientUnits', 'hanging',
'height', 'horiz-adv-x', 'horiz-origin-x', 'id', 'ideographic', 'k',
'keyPoints', 'keySplines', 'keyTimes', 'lang', 'marker-end',
'marker-mid', 'marker-start', 'markerHeight', 'markerUnits',
'markerWidth', 'mathematical', 'max', 'min', 'name', 'offset',
'opacity', 'orient', 'origin', 'overline-position',
'overline-thickness', 'panose-1', 'path', 'pathLength', 'points',
'preserveAspectRatio', 'r', 'refX', 'refY', 'repeatCount',
'repeatDur', 'requiredExtensions', 'requiredFeatures', 'restart',
'rotate', 'rx', 'ry', 'slope', 'stemh', 'stemv', 'stop-color',
'stop-opacity', 'strikethrough-position', 'strikethrough-thickness',
'stroke', 'stroke-dasharray', 'stroke-dashoffset', 'stroke-linecap',
'stroke-linejoin', 'stroke-miterlimit', 'stroke-opacity',
'stroke-width', 'systemLanguage', 'target', 'text-anchor', 'to',
'transform', 'type', 'u1', 'u2', 'underline-position',
'underline-thickness', 'unicode', 'unicode-range', 'units-per-em',
'values', 'version', 'viewBox', 'visibility', 'width', 'widths', 'x',
'x-height', 'x1', 'x2', 'xlink:actuate', 'xlink:arcrole',
'xlink:href', 'xlink:role', 'xlink:show', 'xlink:title', 'xlink:type',
'xml:base', 'xml:lang', 'xml:space', 'xmlns', 'xmlns:xlink', 'y',
'y1', 'y2', 'zoomAndPan']
attr_val_is_uri = ['href', 'src', 'cite', 'action', 'longdesc', 'poster', 'background', 'datasrc',
'dynsrc', 'lowsrc', 'ping', 'poster', 'xlink:href', 'xml:base']
svg_attr_val_allows_ref = ['clip-path', 'color-profile', 'cursor', 'fill',
'filter', 'marker', 'marker-start', 'marker-mid', 'marker-end',
'mask', 'stroke']
svg_allow_local_href = ['altGlyph', 'animate', 'animateColor',
'animateMotion', 'animateTransform', 'cursor', 'feImage', 'filter',
'linearGradient', 'pattern', 'radialGradient', 'textpath', 'tref',
'set', 'use']
acceptable_css_properties = ['azimuth', 'background-color',
'border-bottom-color', 'border-collapse', 'border-color',
'border-left-color', 'border-right-color', 'border-top-color', 'clear',
'color', 'cursor', 'direction', 'display', 'elevation', 'float', 'font',
'font-family', 'font-size', 'font-style', 'font-variant', 'font-weight',
'height', 'letter-spacing', 'line-height', 'overflow', 'pause',
'pause-after', 'pause-before', 'pitch', 'pitch-range', 'richness',
'speak', 'speak-header', 'speak-numeral', 'speak-punctuation',
'speech-rate', 'stress', 'text-align', 'text-decoration', 'text-indent',
'unicode-bidi', 'vertical-align', 'voice-family', 'volume',
'white-space', 'width']
acceptable_css_keywords = ['auto', 'aqua', 'black', 'block', 'blue',
'bold', 'both', 'bottom', 'brown', 'center', 'collapse', 'dashed',
'dotted', 'fuchsia', 'gray', 'green', '!important', 'italic', 'left',
'lime', 'maroon', 'medium', 'none', 'navy', 'normal', 'nowrap', 'olive',
'pointer', 'purple', 'red', 'right', 'solid', 'silver', 'teal', 'top',
'transparent', 'underline', 'white', 'yellow']
acceptable_svg_properties = ['fill', 'fill-opacity', 'fill-rule',
'stroke', 'stroke-width', 'stroke-linecap', 'stroke-linejoin',
'stroke-opacity']
acceptable_protocols = ['ed2k', 'ftp', 'http', 'https', 'irc',
'mailto', 'news', 'gopher', 'nntp', 'telnet', 'webcal',
'xmpp', 'callto', 'feed', 'urn', 'aim', 'rsync', 'tag',
'ssh', 'sftp', 'rtsp', 'afs', 'data']
acceptable_content_types = ['image/png', 'image/jpeg', 'image/gif', 'image/webp', 'image/bmp', 'text/plain']
# subclasses may define their own versions of these constants
allowed_elements = acceptable_elements + mathml_elements + svg_elements
allowed_attributes = acceptable_attributes + mathml_attributes + svg_attributes
allowed_css_properties = acceptable_css_properties
allowed_css_keywords = acceptable_css_keywords
allowed_svg_properties = acceptable_svg_properties
allowed_protocols = acceptable_protocols
allowed_content_types = acceptable_content_types
# Sanitize the +html+, escaping all elements not in ALLOWED_ELEMENTS, and
# stripping out all # attributes not in ALLOWED_ATTRIBUTES. Style
# attributes are parsed, and a restricted set, # specified by
# ALLOWED_CSS_PROPERTIES and ALLOWED_CSS_KEYWORDS, are allowed through.
# attributes in ATTR_VAL_IS_URI are scanned, and only URI schemes specified
# in ALLOWED_PROTOCOLS are allowed.
#
# sanitize_html('<script> do_nasty_stuff() </script>')
# => <script> do_nasty_stuff() </script>
# sanitize_html('<a href="javascript: sucker();">Click here for $100</a>')
# => <a>Click here for $100</a>
def sanitize_token(self, token):
# accommodate filters which use token_type differently
token_type = token["type"]
if token_type in list(tokenTypes.keys()):
token_type = tokenTypes[token_type]
if token_type in (tokenTypes["StartTag"], tokenTypes["EndTag"],
tokenTypes["EmptyTag"]):
if token["name"] in self.allowed_elements:
return self.allowed_token(token, token_type)
else:
return self.disallowed_token(token, token_type)
elif token_type == tokenTypes["Comment"]:
pass
else:
return token
def allowed_token(self, token, token_type):
if "data" in token:
attrs = dict([(name, val) for name, val in
token["data"][::-1]
if name in self.allowed_attributes])
for attr in self.attr_val_is_uri:
if attr not in attrs:
continue
val_unescaped = re.sub("[`\000-\040\177-\240\s]+", '',
unescape(attrs[attr])).lower()
# remove replacement characters from unescaped characters
val_unescaped = val_unescaped.replace("\ufffd", "")
uri = urlparse.urlparse(val_unescaped)
if uri and uri.scheme:
if uri.scheme not in self.allowed_protocols:
del attrs[attr]
if uri.scheme == 'data':
m = content_type_rgx.match(uri.path)
if not m:
del attrs[attr]
elif m.group('content_type') not in self.allowed_content_types:
del attrs[attr]
for attr in self.svg_attr_val_allows_ref:
if attr in attrs:
attrs[attr] = re.sub(r'url\s*\(\s*[^#\s][^)]+?\)',
' ',
unescape(attrs[attr]))
if (token["name"] in self.svg_allow_local_href and
'xlink:href' in attrs and re.search('^\s*[^#\s].*',
attrs['xlink:href'])):
del attrs['xlink:href']
if 'style' in attrs:
attrs['style'] = self.sanitize_css(attrs['style'])
token["data"] = [[name, val] for name, val in list(attrs.items())]
return token
def disallowed_token(self, token, token_type):
if token_type == tokenTypes["EndTag"]:
token["data"] = "</%s>" % token["name"]
elif token["data"]:
attrs = ''.join([' %s="%s"' % (k, escape(v)) for k, v in token["data"]])
token["data"] = "<%s%s>" % (token["name"], attrs)
else:
token["data"] = "<%s>" % token["name"]
if token.get("selfClosing"):
token["data"] = token["data"][:-1] + "/>"
if token["type"] in list(tokenTypes.keys()):
token["type"] = "Characters"
else:
token["type"] = tokenTypes["Characters"]
del token["name"]
return token
def sanitize_css(self, style):
# disallow urls
style = re.compile('url\s*\(\s*[^\s)]+?\s*\)\s*').sub(' ', style)
# gauntlet
if not re.match("""^([:,;#%.\sa-zA-Z0-9!]|\w-\w|'[\s\w]+'|"[\s\w]+"|\([\d,\s]+\))*$""", style):
return ''
if not re.match("^\s*([-\w]+\s*:[^:;]*(;\s*|$))*$", style):
return ''
clean = []
for prop, value in re.findall("([-\w]+)\s*:\s*([^:;]*)", style):
if not value:
continue
if prop.lower() in self.allowed_css_properties:
clean.append(prop + ': ' + value + ';')
elif prop.split('-')[0].lower() in ['background', 'border', 'margin',
'padding']:
for keyword in value.split():
if keyword not in self.acceptable_css_keywords and \
not re.match("^(#[0-9a-f]+|rgb\(\d+%?,\d*%?,?\d*%?\)?|\d{0,2}\.?\d{0,2}(cm|em|ex|in|mm|pc|pt|px|%|,|\))?)$", keyword):
break
else:
clean.append(prop + ': ' + value + ';')
elif prop.lower() in self.allowed_svg_properties:
clean.append(prop + ': ' + value + ';')
return ' '.join(clean)
class HTMLSanitizer(HTMLTokenizer, HTMLSanitizerMixin):
def __init__(self, stream, encoding=None, parseMeta=True, useChardet=True,
lowercaseElementName=False, lowercaseAttrName=False, parser=None):
# Change case matching defaults as we only output lowercase html anyway
# This solution doesn't seem ideal...
HTMLTokenizer.__init__(self, stream, encoding, parseMeta, useChardet,
lowercaseElementName, lowercaseAttrName, parser=parser)
def __iter__(self):
for token in HTMLTokenizer.__iter__(self):
token = self.sanitize_token(token)
if token:
yield token