view tests/sslcerts/priv.pem @ 30766:d7bf7d2bd5ab

hgweb: support Content Security Policy

Content-Security-Policy (CSP) is a web security feature that allows
servers to declare what loaded content is allowed to do. For example,
a policy can prevent loading of images, JavaScript, CSS, etc unless
the source of that content is whitelisted (by hostname, URI scheme,
hashes of content, etc). It's a nifty security feature that provides
extra mitigation against some attacks, notably XSS.

Mitigation against these attacks is important for Mercurial because
hgweb renders repository data, which is commonly untrusted. While we
make attempts to escape things, etc, there's the possibility that
malicious data could be injected into the site content. If this happens
today, the full power of the web browser is available to that
malicious content. A restrictive CSP policy (defined by the server
operator and sent in an HTTP header which is outside the control of
malicious content), could restrict browser capabilities and mitigate
security problems posed by malicious data.

CSP works by emitting an HTTP header declaring the policy that browsers
should apply. Ideally, this header would be emitted by a layer above
Mercurial (likely the HTTP server doing the WSGI "proxying"). This
works for some CSP policies, but not all.

For example, policies to allow inline JavaScript may require setting
a "nonce" attribute on <script>. This attribute value must be unique
and non-guessable. And, the value must be present in the HTTP header
and the HTML body. This means that coordinating the value between
Mercurial and another HTTP server could be difficult: it is much
easier to generate and emit the nonce in a central location.

This commit introduces support for emitting a
Content-Security-Policy header from hgweb. A config option defines
the header value. If present, the header is emitted. A special
"%nonce%" syntax in the value triggers generation of a nonce and
inclusion in <script> elements in templates. The inclusion of a
nonce does not occur unless "%nonce%" is present. This makes this
commit completely backwards compatible and the feature opt-in.

The nonce is a type 4 UUID, which is the flavor that is randomly
generated. It has 122 random bits, which should be plenty to satisfy
the guarantees of a nonce.

-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----