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Refactor CSP filter:

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- Move default 'unsafe-inline' for style-src and style-src-elem into get_csp_flags
- Ensure hashes are only added if 'unsafe-inline' not in final tokens
- Improve comments and structure
- Extend unit tests to cover default flags, overrides, and final-token logic
See: https://chatgpt.com/share/68b54520-5cfc-800f-9bac-45093740df78
This commit is contained in:
Kevin Veen-Birkenbach
2025-09-01 09:03:22 +02:00
parent 3bfab9ef8e
commit 3f8e7c1733
2 changed files with 178 additions and 49 deletions
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127
filter_plugins/csp_filters.py
View File

@@ -1,12 +1,15 @@
from ansible.errors import AnsibleFilterError
import hashlib
import base64
import sys, os
import sys
import os
# Ensure module_utils is importable when this filter runs from Ansible
sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '..')))
from module_utils.config_utils import get_app_conf
from module_utils.get_url import get_url
class FilterModule(object):
"""
Custom filters for Content Security Policy generation and CSP-related utilities.
@@ -17,10 +20,14 @@ class FilterModule(object):
'build_csp_header': self.build_csp_header,
}
# -------------------------------
# Helpers
# -------------------------------
@staticmethod
def is_feature_enabled(applications: dict, feature: str, application_id: str) -> bool:
"""
Return True if applications[application_id].features[feature] is truthy.
Returns True if applications[application_id].features[feature] is truthy.
"""
return get_app_conf(
applications,
@@ -32,6 +39,10 @@ class FilterModule(object):
@staticmethod
def get_csp_whitelist(applications, application_id, directive):
"""
Returns a list of additional whitelist entries for a given directive.
Accepts both scalar and list in config; always returns a list.
"""
wl = get_app_conf(
applications,
application_id,
@@ -48,28 +59,37 @@ class FilterModule(object):
@staticmethod
def get_csp_flags(applications, application_id, directive):
"""
Dynamically extract all CSP flags for a given directive and return them as tokens,
e.g., "'unsafe-eval'", "'unsafe-inline'", etc.
Returns CSP flag tokens (e.g., "'unsafe-eval'", "'unsafe-inline'") for a directive,
merging sane defaults with app config.
Default: 'unsafe-inline' is enabled for style-src and style-src-elem.
"""
flags = get_app_conf(
# Defaults that apply to all apps
default_flags = {}
if directive in ('style-src', 'style-src-elem'):
default_flags = {'unsafe-inline': True}
configured = get_app_conf(
applications,
application_id,
'server.csp.flags.' + directive,
False,
{}
)
tokens = []
for flag_name, enabled in flags.items():
# Merge defaults with configured flags (configured overrides defaults)
merged = {**default_flags, **configured}
tokens = []
for flag_name, enabled in merged.items():
if enabled:
tokens.append(f"'{flag_name}'")
return tokens
@staticmethod
def get_csp_inline_content(applications, application_id, directive):
"""
Return inline script/style snippets to hash for a given CSP directive.
Returns inline script/style snippets to hash for a given directive.
Accepts both scalar and list in config; always returns a list.
"""
snippets = get_app_conf(
applications,
@@ -87,7 +107,7 @@ class FilterModule(object):
@staticmethod
def get_csp_hash(content):
"""
Compute the SHA256 hash of the given inline content and return
Computes the SHA256 hash of the given inline content and returns
a CSP token like "'sha256-<base64>'".
"""
try:
@@ -97,6 +117,10 @@ class FilterModule(object):
except Exception as exc:
raise AnsibleFilterError(f"get_csp_hash failed: {exc}")
# -------------------------------
# Main builder
# -------------------------------
def build_csp_header(
self,
applications,
@@ -106,75 +130,80 @@ class FilterModule(object):
matomo_feature_name='matomo'
):
"""
Build the Content-Security-Policy header value dynamically based on application settings.
Inline hashes are read from applications[application_id].csp.hashes
Builds the Content-Security-Policy header value dynamically based on application settings.
- Flags (e.g., 'unsafe-eval', 'unsafe-inline') are read from server.csp.flags.<directive>,
with sane defaults applied in get_csp_flags (always 'unsafe-inline' for style-src and style-src-elem).
- Inline hashes are read from server.csp.hashes.<directive>.
- Whitelists are read from server.csp.whitelist.<directive>.
- Inline hashes are added only if the final tokens do NOT include 'unsafe-inline'.
"""
try:
directives = [
'default-src', # Fallback source list for all content types not explicitly listed
'connect-src', # Controls allowed URLs for XHR, WebSockets, EventSource, and fetch()
'frame-ancestors', # Restricts which parent frames can embed this page via <iframe>, <object>, <embed>, <applet>
'frame-src', # Controls allowed sources for nested browsing contexts like <iframe>
'script-src', # Controls allowed sources for inline scripts and <script> elements (general script execution)
'script-src-elem', # Controls allowed sources specifically for <script> elements (separate from inline/event handlers)
'style-src', # Controls allowed sources for inline styles and <style>/<link> elements (general styles)
'style-src-elem', # Controls allowed sources specifically for <style> and <link rel="stylesheet"> elements
'font-src', # Controls allowed sources for fonts loaded via @font-face
'worker-src', # Controls allowed sources for web workers, shared workers, and service workers
'manifest-src', # Controls allowed sources for web app manifests
'media-src', # Controls allowed sources for media files like <audio> and <video>
'default-src', # Fallback source list for content types not explicitly listed
'connect-src', # Allowed URLs for XHR, WebSockets, EventSource, fetch()
'frame-ancestors', # Who may embed this page
'frame-src', # Sources for nested browsing contexts (e.g., <iframe>)
'script-src', # Sources for script execution
'script-src-elem', # Sources for <script> elements
'style-src', # Sources for inline styles and <style>/<link> elements
'style-src-elem', # Sources for <style> and <link rel="stylesheet">
'font-src', # Sources for fonts
'worker-src', # Sources for workers
'manifest-src', # Sources for web app manifests
'media-src', # Sources for audio and video
]
parts = []
for directive in directives:
tokens = ["'self'"]
# unsafe-eval / unsafe-inline flags
# 1) Load flags (includes defaults from get_csp_flags)
flags = self.get_csp_flags(applications, application_id, directive)
tokens += flags
if directive in [ 'script-src-elem', 'connect-src', 'style-src-elem' ]:
# Allow fetching from internal CDN as default for all applications
tokens.append(get_url(domains,'web-svc-cdn',web_protocol))
if directive in ['script-src-elem', 'connect-src']:
# Matomo integration
if self.is_feature_enabled(applications, matomo_feature_name, application_id):
tokens.append(get_url(domains,'web-app-matomo',web_protocol))
# 2) Allow fetching from internal CDN by default for selected directives
if directive in ['script-src-elem', 'connect-src', 'style-src-elem']:
tokens.append(get_url(domains, 'web-svc-cdn', web_protocol))
# ReCaptcha integration: allow loading scripts from Google if feature enabled
# 3) Matomo integration if feature is enabled
if directive in ['script-src-elem', 'connect-src']:
if self.is_feature_enabled(applications, matomo_feature_name, application_id):
tokens.append(get_url(domains, 'web-app-matomo', web_protocol))
# 4) ReCaptcha integration (scripts + frames) if feature is enabled
if self.is_feature_enabled(applications, 'recaptcha', application_id):
if directive in ['script-src-elem',"frame-src"]:
if directive in ['script-src-elem', 'frame-src']:
tokens.append('https://www.gstatic.com')
tokens.append('https://www.google.com')
# 5) Frame ancestors handling (desktop + logout support)
if directive == 'frame-ancestors':
# Enable loading via ancestors
if self.is_feature_enabled(applications, 'desktop', application_id):
# Allow being embedded by the desktop app domain (and potentially its parent)
domain = domains.get('web-app-desktop')[0]
sld_tld = ".".join(domain.split(".")[-2:]) # yields "example.com"
tokens.append(f"{sld_tld}") # yields "*.example.com"
sld_tld = ".".join(domain.split(".")[-2:]) # e.g., example.com
tokens.append(f"{sld_tld}")
if self.is_feature_enabled(applications, 'logout', application_id):
# Allow logout via infinito logout proxy
tokens.append(get_url(domains,'web-svc-logout',web_protocol))
# Allow logout via keycloak app
tokens.append(get_url(domains,'web-app-keycloak',web_protocol))
# Allow embedding via logout proxy and Keycloak app
tokens.append(get_url(domains, 'web-svc-logout', web_protocol))
tokens.append(get_url(domains, 'web-app-keycloak', web_protocol))
# whitelist
# 6) Custom whitelist entries
tokens += self.get_csp_whitelist(applications, application_id, directive)
# only add hashes if 'unsafe-inline' is NOT in flags
if "'unsafe-inline'" not in flags:
# 7) Add inline content hashes ONLY if final tokens do NOT include 'unsafe-inline'
# (Check tokens, not flags, to include defaults and later modifications.)
if "'unsafe-inline'" not in tokens:
for snippet in self.get_csp_inline_content(applications, application_id, directive):
tokens.append(self.get_csp_hash(snippet))
# Append directive
parts.append(f"{directive} {' '.join(tokens)};")
# static img-src
# 8) Static img-src directive (kept permissive for data/blob and any host)
parts.append("img-src * data: blob:;")
return ' '.join(parts)
except Exception as exc:

100
tests/unit/filter_plugins/test_csp_filters.py
View File

@@ -222,6 +222,106 @@ class TestCspFilters(unittest.TestCase):
# Should no longer contain the SLD+TLD
self.assertNotIn("domain-example.com", header_no)
def test_flags_default_unsafe_inline_for_styles(self):
"""
get_csp_flags should default to include 'unsafe-inline' for style-src and style-src-elem,
even when no explicit flags are configured.
"""
# No explicit flags for app2
self.assertIn("'unsafe-inline'", self.filter.get_csp_flags(self.apps, 'app2', 'style-src'))
self.assertIn("'unsafe-inline'", self.filter.get_csp_flags(self.apps, 'app2', 'style-src-elem'))
# Non-style directive should NOT get unsafe-inline by default
self.assertNotIn("'unsafe-inline'", self.filter.get_csp_flags(self.apps, 'app2', 'script-src'))
def test_style_src_hashes_suppressed_by_default(self):
"""
Because 'unsafe-inline' is defaulted for style-src, hashes for style-src should NOT be included.
"""
header = self.filter.build_csp_header(self.apps, 'app1', self.domains, web_protocol='https')
style_hash = self.filter.get_csp_hash("body { background: #fff; }")
self.assertNotIn(style_hash, header)
# Ensure 'unsafe-inline' actually present in style-src directive
tokens = self._get_directive_tokens(header, 'style-src')
self.assertIn("'unsafe-inline'", tokens)
def test_style_src_override_disables_inline_and_enables_hashes(self):
"""
If an app explicitly disables 'unsafe-inline' for style-src, then hashes MUST appear.
"""
# Configure override: disable unsafe-inline for style-src
self.apps.setdefault('app1', {}).setdefault('server', {}).setdefault('csp', {}).setdefault('flags', {}).setdefault('style-src', {})
self.apps['app1']['server']['csp']['flags']['style-src']['unsafe-inline'] = False
# Also ensure there is a style-src hash to include
self.apps['app1']['server']['csp']['hashes']['style-src'] = "body { background: #fff; }"
header = self.filter.build_csp_header(self.apps, 'app1', self.domains, web_protocol='https')
# Then the style hash SHOULD be present
style_hash = self.filter.get_csp_hash("body { background: #fff; }")
self.assertIn(style_hash, header)
# And 'unsafe-inline' should NOT be present in style-src tokens
tokens = self._get_directive_tokens(header, 'style-src')
self.assertNotIn("'unsafe-inline'", tokens)
def test_style_src_elem_default_unsafe_inline(self):
"""
style-src-elem should include 'unsafe-inline' by default (from get_csp_flags defaults).
"""
header = self.filter.build_csp_header(self.apps, 'app1', self.domains, web_protocol='https')
tokens = self._get_directive_tokens(header, 'style-src-elem')
self.assertIn("'unsafe-inline'", tokens)
def test_script_src_hash_behavior_depends_on_unsafe_inline_flag(self):
"""
For script-src:
- When unsafe-inline=False (as in app1), hashes SHOULD be included.
- If we flip unsafe-inline=True, hashes should NOT be included.
"""
# Baseline (from setUp): app1 script-src has unsafe-inline=False and one hash
header = self.filter.build_csp_header(self.apps, 'app1', self.domains, web_protocol='https')
script_hash = self.filter.get_csp_hash("console.log('hello');")
self.assertIn(script_hash, header)
# Now toggle unsafe-inline=True and ensure hash disappears
self.apps['app1']['server']['csp']['flags']['script-src']['unsafe-inline'] = True
header_inline = self.filter.build_csp_header(self.apps, 'app1', self.domains, web_protocol='https')
self.assertNotIn(script_hash, header_inline)
# And 'unsafe-inline' should be present in the script-src tokens now
tokens = self._get_directive_tokens(header_inline, 'script-src')
self.assertIn("'unsafe-inline'", tokens)
def test_hashes_guard_checks_final_tokens_not_only_flags(self):
"""
Ensure the 'no-hash-when-unsafe-inline' rule is driven by FINAL tokens,
not just raw flags: simulate default-provided 'unsafe-inline' (style-src)
without explicitly setting it in flags and verify hashes are still suppressed.
"""
# Remove explicit style-src flags entirely to rely solely on defaults
self.apps['app1']['server']['csp']['flags'].pop('style-src', None)
# Provide a style-src hash
self.apps['app1']['server']['csp']['hashes']['style-src'] = "body { color: blue; }"
style_hash = self.filter.get_csp_hash("body { color: blue; }")
header = self.filter.build_csp_header(self.apps, 'app1', self.domains, web_protocol='https')
# Because defaults include 'unsafe-inline' for style-src, the hash MUST NOT appear
self.assertNotIn(style_hash, header)
# And 'unsafe-inline' must appear in final tokens
tokens = self._get_directive_tokens(header, 'style-src')
self.assertIn("'unsafe-inline'", tokens)
if __name__ == '__main__':
unittest.main()