From f25254f6d0a0aa5953bd8029a9e8a372c6cb8691 Mon Sep 17 00:00:00 2001
From: ilayda-cp <ilayda.cavusoglupars@canonical.com>
Date: Fri, 6 Sep 2024 12:35:25 +0300
Subject: [PATCH] feat: add csp (#1993)

* feat: add csp

* feat: Add security headers
---
 webapp/handlers.py | 74 ++++++++++++++++++++++++++++++++++++++++++++++
 webapp/helpers.py  |  8 +++++
 2 files changed, 82 insertions(+)

diff --git a/webapp/handlers.py b/webapp/handlers.py
index 14adffabc..0b1aaed97 100644
--- a/webapp/handlers.py
+++ b/webapp/handlers.py
@@ -15,6 +15,51 @@
 
 from webapp import authentication, helpers
 
+CSP = {
+    "default-src": ["'self'"],
+    "img-src": [
+        "'self'",
+        "data: blob:",
+        "assets.ubuntu.com",
+        "res.cloudinary.com",
+        "api.charmhub.io",
+        "charmhub.io",
+        "*.cdn.snapcraftcontent.com",
+        "www.googletagmanager.com",
+    ],
+    "script-src-elem": [
+        "'self'",
+        "assets.ubuntu.com",
+        "www.googletagmanager.com",
+        "*.crazyegg.com",
+        "w.usabilla.com",
+        # This is necessary for Google Tag Manager to function properly.
+        "'unsafe-inline'",
+    ],
+    "font-src": [
+        "'self'",
+        "assets.ubuntu.com",
+    ],
+    "script-src": [
+        "'self'",
+        "blob:",
+        "'unsafe-eval'",
+        "'unsafe-hashes'",
+    ],
+    "connect-src": [
+        "'self'",
+        "sentry.is.canonical.com",
+        "*.crazyegg.com",
+    ],
+    "frame-src": [
+        "'self'",
+    ],
+    "style-src": [
+        "'self'",
+        "'unsafe-inline'",
+    ],
+}
+
 
 def charmhub_utility_processor():
     """
@@ -87,3 +132,32 @@ def handle_store_api_error(e):
             ),
             status_code,
         )
+
+    @app.after_request
+    def add_headers(response):
+        """
+        Security headers to add to all requests
+        - Content-Security-Policy: Restrict resources (e.g., JavaScript, CSS,
+        Images) and URLs
+        - Referrer-Policy: Limit referrer data for security while preserving
+        full referrer for same-origin requests
+        - Cross-Origin-Embedder-Policy: allows embedding cross-origin
+        resources without credentials
+        - Cross-Origin-Opener-Policy: enable the page to open pop-ups while
+        maintaining same-origin policy
+        - Cross-Origin-Resource-Policy: allowing only same-origin requests to
+        access the resource
+        - X-Permitted-Cross-Domain-Policies: disallows cross-domain access to
+        resources
+        """
+        response.headers["Content-Security-Policy"] = helpers.get_csp_as_str(
+            CSP
+        )
+        response.headers["Referrer-Policy"] = "strict-origin-when-cross-origin"
+        response.headers["Cross-Origin-Embedder-Policy"] = "credentialless"
+        response.headers["Cross-Origin-Opener-Policy"] = (
+            "same-origin-allow-popups"
+        )
+        response.headers["Cross-Origin-Resource-Policy"] = "same-site"
+        response.headers["X-Permitted-Cross-Domain-Policies"] = "none"
+        return response
diff --git a/webapp/helpers.py b/webapp/helpers.py
index e079bea1c..c959dab2b 100644
--- a/webapp/helpers.py
+++ b/webapp/helpers.py
@@ -151,3 +151,11 @@ def param_redirect_exec(req, make_response, redirect):
             response.set_cookie("param_redirect", "", expires=0)
             return response
     return None
+
+
+def get_csp_as_str(csp={}):
+    csp_str = ""
+    for key, values in csp.items():
+        csp_value = " ".join(values)
+        csp_str += f"{key} {csp_value}; "
+    return csp_str.strip()