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Fix Swagger /docs page blocked by CSP #12

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Merged
JuliusScheuerer merged 1 commit into from
Mar 25, 2026
Merged

Fix Swagger /docs page blocked by CSP #12

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38 changes: 28 additions & 10 deletions src/document_anonymizer/security/middleware.py
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,8 @@
from starlette.responses import Response

_STATIC_PATH_PREFIX = "/static/"
_SWAGGER_CDN = "https://cdn.jsdelivr.net"
_SWAGGER_PATHS = ("/docs", "/openapi.json")

# Number of random bytes for CSP nonce (16 bytes = 128 bits of entropy)
_CSP_NONCE_BYTES = 16
Expand Down Expand Up @@ -41,16 +43,32 @@ async def dispatch(
response.headers["Strict-Transport-Security"] = (
"max-age=31536000; includeSubDomains"
)
response.headers["Content-Security-Policy"] = (
"default-src 'self'; "
f"script-src 'self' 'nonce-{csp_nonce}'; "
"style-src 'self' 'unsafe-inline'; "
"img-src 'self' data:; "
"font-src 'self'; "
"frame-ancestors 'none'; "
"base-uri 'self'; "
"form-action 'self'"
)
# Swagger UI (/docs) loads JS/CSS from cdn.jsdelivr.net and
# uses inline scripts that don't carry our nonce. Relax CSP
# for the docs path only — it serves no user data.
is_swagger = request.url.path in _SWAGGER_PATHS
if is_swagger:
response.headers["Content-Security-Policy"] = (
"default-src 'self'; "
f"script-src 'self' 'unsafe-inline' {_SWAGGER_CDN}; "
f"style-src 'self' 'unsafe-inline' {_SWAGGER_CDN}; "
f"img-src 'self' data: {_SWAGGER_CDN}; "
"font-src 'self'; "
"frame-ancestors 'none'; "
"base-uri 'self'; "
"form-action 'self'"
)
else:
response.headers["Content-Security-Policy"] = (
"default-src 'self'; "
f"script-src 'self' 'nonce-{csp_nonce}'; "
"style-src 'self' 'unsafe-inline'; "
"img-src 'self' data:; "
"font-src 'self'; "
"frame-ancestors 'none'; "
"base-uri 'self'; "
"form-action 'self'"
)
response.headers["Permissions-Policy"] = (
"camera=(), microphone=(), geolocation=()"
)
Expand Down