Rework the response headers in the server configs

1 file changed, 38 insertions, 8 deletions

diff --git a/custom/servers/lighttpd.conf b/custom/servers/lighttpd.conf
index 6ae87e0..dcfb43d 100644
--- a/custom/servers/lighttpd.conf
+++ b/custom/servers/lighttpd.conf
@@ -73,17 +73,47 @@ $HTTP["host"] == "git.example.org" {
     # the same path used here, but setting it makes the location explicit.
     setenv.add-environment = ( "CGIT_CONFIG" => "/etc/cgitrc" )
 
-    # Security headers are set here, not in cgit, so they also cover the
-    # static assets lighttpd serves. script-src stays self because cgit loads
-    # only its own cgit.js, and style-src allows inline for the diffstat bars.
-    # If you enable the gravatar or libravatar avatar filter, add its host to
-    # img-src.
+    # Site-wide security headers are set here so they also cover the static
+    # assets lighttpd serves. cgit itself sends only the headers the server
+    # cannot supply. Those are Status, Content-Type, Content-Length and
+    # Content-Disposition on downloads, a no-store Cache-Control on
+    # unauthenticated responses, the auth filter's Set-Cookie, and on raw
+    # repository bytes a nosniff of its own next to the stricter policy
+    # "default-src 'none'". Everything else, this policy included, is the
+    # server's job.
+    #
+    # The add in add-response-header is load bearing. It appends a second
+    # copy next to what cgit emitted, so a raw page carries both policies and
+    # the browser enforces the stricter one, while the doubled nosniff line
+    # is harmless. The set-response-header directive would instead replace
+    # what cgit sent, swapping the strict policy on raw repository content
+    # for this looser site one. Never switch add to set.
+    #
+    # script-src stays self because cgit loads only its own cgit.js, and
+    # style-src allows inline for the diffstat bars. form-action self covers
+    # the login form, the only form cgit renders. If you enable the gravatar
+    # or libravatar avatar filter, add its host to img-src.
+    #
+    # Permissions-Policy refuses the browser features a git viewer never asks
+    # for, camera and location among them, for everything served here,
+    # repository files included. The opener policy cuts any window.opener
+    # link between cgit and pages that open it, and the resource policy stops
+    # other origins from embedding what cgit serves, a hotlinked raw file for
+    # example. git clients are not browsers and ignore both, so clone and
+    # snapshot downloads keep working. The stricter
+    # Cross-Origin-Embedder-Policy is deliberately absent because it would
+    # break the avatar filters mentioned above.
     setenv.add-response-header = (
-        "Content-Security-Policy" => "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; object-src 'none'; base-uri 'none'; frame-ancestors 'self'",
+        "Content-Security-Policy" => "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; object-src 'none'; base-uri 'none'; frame-ancestors 'self'; form-action 'self'",
         "X-Content-Type-Options" => "nosniff",
-        "Referrer-Policy" => "no-referrer"
+        "Referrer-Policy" => "no-referrer",
+        "Permissions-Policy" => "accelerometer=(), autoplay=(), camera=(), display-capture=(), geolocation=(), gyroscope=(), magnetometer=(), microphone=(), midi=(), payment=(), picture-in-picture=(), usb=()",
+        "Cross-Origin-Opener-Policy" => "same-origin",
+        "Cross-Origin-Resource-Policy" => "same-origin"
     )
-    # Enable only once you serve HTTPS exclusively, since it is hard to undo.
+    # Two years of forced HTTPS. Enable this together with the TLS socket at
+    # the end of this file and only once you serve HTTPS exclusively, since
+    # it is hard to undo once browsers have seen it.
     #setenv.add-response-header += ( "Strict-Transport-Security" => "max-age=63072000; includeSubDomains" )
 
     # Register the cgit binary as a CGI program. The key cgit.cgi matches the