139 lines
4.0 KiB
Python
139 lines
4.0 KiB
Python
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"""
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NBConvert Preprocessor for sanitizing HTML rendering of notebooks.
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"""
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from bleach import (
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ALLOWED_ATTRIBUTES,
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ALLOWED_STYLES,
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ALLOWED_TAGS,
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clean,
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)
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from traitlets import (
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Any,
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Bool,
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List,
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Set,
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Unicode,
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)
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from .base import Preprocessor
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class SanitizeHTML(Preprocessor):
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# Bleach config.
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attributes = Any(
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config=True,
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default_value=ALLOWED_ATTRIBUTES,
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help="Allowed HTML tag attributes",
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)
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tags = List(
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Unicode(),
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config=True,
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default_value=ALLOWED_TAGS,
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help="List of HTML tags to allow",
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)
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styles = List(
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Unicode(),
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config=True,
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default_value=ALLOWED_STYLES,
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help="Allowed CSS styles if <style> tag is whitelisted"
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)
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strip = Bool(
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config=True,
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default_value=False,
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help="If True, remove unsafe markup entirely instead of escaping"
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)
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strip_comments = Bool(
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config=True,
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default_value=True,
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help="If True, strip comments from escaped HTML",
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)
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# Display data config.
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safe_output_keys = Set(
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config=True,
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default_value={
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'metadata', # Not a mimetype per-se, but expected and safe.
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'text/plain',
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'text/latex',
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'application/json',
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'image/png',
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'image/jpeg',
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},
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help="Cell output mimetypes to render without modification",
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)
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sanitized_output_types = Set(
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config=True,
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default_value={
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'text/html',
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'text/markdown',
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},
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help="Cell output types to display after escaping with Bleach.",
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)
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def preprocess_cell(self, cell, resources, cell_index):
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"""
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Sanitize potentially-dangerous contents of the cell.
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Cell Types:
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raw:
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Sanitize literal HTML
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markdown:
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Sanitize literal HTML
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code:
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Sanitize outputs that could result in code execution
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"""
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if cell.cell_type == 'raw':
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# Sanitize all raw cells anyway.
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# Only ones with the text/html mimetype should be emitted
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# but erring on the side of safety maybe.
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cell.source = self.sanitize_html_tags(cell.source)
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return cell, resources
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elif cell.cell_type == 'markdown':
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cell.source = self.sanitize_html_tags(cell.source)
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return cell, resources
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elif cell.cell_type == 'code':
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cell.outputs = self.sanitize_code_outputs(cell.outputs)
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return cell, resources
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def sanitize_code_outputs(self, outputs):
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"""
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Sanitize code cell outputs.
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Removes 'text/javascript' fields from display_data outputs, and
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runs `sanitize_html_tags` over 'text/html'.
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"""
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for output in outputs:
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# These are always ascii, so nothing to escape.
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if output['output_type'] in ('stream', 'error'):
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continue
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data = output.data
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to_remove = []
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for key in data:
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if key in self.safe_output_keys:
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continue
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elif key in self.sanitized_output_types:
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self.log.info("Sanitizing %s" % key)
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data[key] = self.sanitize_html_tags(data[key])
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else:
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# Mark key for removal. (Python doesn't allow deletion of
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# keys from a dict during iteration)
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to_remove.append(key)
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for key in to_remove:
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self.log.info("Removing %s" % key)
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del data[key]
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return outputs
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def sanitize_html_tags(self, html_str):
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"""
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Sanitize a string containing raw HTML tags.
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"""
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return clean(
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html_str,
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tags=self.tags,
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attributes=self.attributes,
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styles=self.styles,
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strip=self.strip,
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strip_comments=self.strip_comments,
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)
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