view tests/test-patchbomb-tls.t @ 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.

#require serve ssl

Set up SMTP server:

  $ CERTSDIR="$TESTDIR/sslcerts"
  $ cat "$CERTSDIR/priv.pem" "$CERTSDIR/pub.pem" >> server.pem

  $ python "$TESTDIR/dummysmtpd.py" -p $HGPORT --pid-file a.pid -d \
  > --tls smtps --certificate `pwd`/server.pem
  listening at localhost:$HGPORT
  $ cat a.pid >> $DAEMON_PIDS

Ensure hg email output is sent to stdout:

  $ unset PAGER

Set up repository:

  $ hg init t
  $ cd t
  $ cat <<EOF >> .hg/hgrc
  > [extensions]
  > patchbomb =
  > [email]
  > method = smtp
  > [smtp]
  > host = localhost
  > port = $HGPORT
  > tls = smtps
  > EOF

  $ echo a > a
  $ hg commit -Ama -d '1 0'
  adding a

Utility functions:

  $ DISABLECACERTS=
  $ try () {
  >   hg email $DISABLECACERTS -f quux -t foo -c bar -r tip "$@"
  > }

Our test cert is not signed by a trusted CA. It should fail to verify if
we are able to load CA certs:

#if sslcontext defaultcacerts no-defaultcacertsloaded
  $ try
  this patch series consists of 1 patches.
  
  
  (an attempt was made to load CA certificates but none were loaded; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this error)
  (?i)abort: .*?certificate.verify.failed.* (re)
  [255]
#endif

#if no-sslcontext defaultcacerts
  $ try
  this patch series consists of 1 patches.
  
  
  warning: connecting to localhost using legacy security technology (TLS 1.0); see https://mercurial-scm.org/wiki/SecureConnections for more info
  (using CA certificates from *; if you see this message, your Mercurial install is not properly configured; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this message) (glob) (?)
  (?i)abort: .*?certificate.verify.failed.* (re)
  [255]
#endif

#if defaultcacertsloaded
  $ try
  this patch series consists of 1 patches.
  
  
  warning: connecting to localhost using legacy security technology (TLS 1.0); see https://mercurial-scm.org/wiki/SecureConnections for more info (?)
  (using CA certificates from *; if you see this message, your Mercurial install is not properly configured; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this message) (glob) (?)
  (?i)abort: .*?certificate.verify.failed.* (re)
  [255]

#endif

#if no-defaultcacerts
  $ try
  this patch series consists of 1 patches.
  
  
  (unable to load * certificates; see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this message) (glob) (?)
  abort: localhost certificate error: no certificate received
  (set hostsecurity.localhost:certfingerprints=sha256:62:09:97:2f:97:60:e3:65:8f:12:5d:78:9e:35:a1:36:7a:65:4b:0e:9f:ac:db:c3:bc:6e:b6:a3:c0:16:e0:30 config setting or use --insecure to connect insecurely)
  [255]
#endif

  $ DISABLECACERTS="--config devel.disableloaddefaultcerts=true"

Without certificates:

  $ try --debug
  this patch series consists of 1 patches.
  
  
  (using smtps)
  sending mail: smtp host localhost, port * (glob)
  warning: connecting to localhost using legacy security technology (TLS 1.0); see https://mercurial-scm.org/wiki/SecureConnections for more info (?)
  (verifying remote certificate)
  abort: unable to verify security of localhost (no loaded CA certificates); refusing to connect
  (see https://mercurial-scm.org/wiki/SecureConnections for how to configure Mercurial to avoid this error or set hostsecurity.localhost:fingerprints=sha256:20:de:b3:ad:b4:cd:a5:42:f0:74:41:1c:a2:70:1e:da:6e:c0:5c:16:9e:e7:22:0f:f1:b7:e5:6e:e4:92:af:7e to trust this server)
  [255]

With global certificates:

  $ try --debug --config web.cacerts="$CERTSDIR/pub.pem"
  this patch series consists of 1 patches.
  
  
  (using smtps)
  sending mail: smtp host localhost, port * (glob)
  warning: connecting to localhost using legacy security technology (TLS 1.0); see https://mercurial-scm.org/wiki/SecureConnections for more info (?)
  (verifying remote certificate)
  sending [PATCH] a ...

With invalid certificates:

  $ try --config web.cacerts="$CERTSDIR/pub-other.pem"
  this patch series consists of 1 patches.
  
  
  warning: connecting to localhost using legacy security technology (TLS 1.0); see https://mercurial-scm.org/wiki/SecureConnections for more info (?)
  (?i)abort: .*?certificate.verify.failed.* (re)
  [255]

  $ cd ..