view tests/test-bad-extension.t @ 29560:303e9300772a

sslutil: require TLS 1.1+ when supported

Currently, Mercurial will use TLS 1.0 or newer when connecting to
remote servers, selecting the highest TLS version supported by both
peers. On older Pythons, only TLS 1.0 is available. On newer Pythons,
TLS 1.1 and 1.2 should be available.

Security professionals recommend avoiding TLS 1.0 if possible.
PCI DSS 3.1 "strongly encourages" the use of TLS 1.2.

Known attacks like BEAST and POODLE exist against TLS 1.0 (although
mitigations are available and properly configured servers aren't
vulnerable).

I asked Eric Rescorla - Mozilla's resident crypto expert - whether
Mercurial should drop support for TLS 1.0. His response was
"if you can get away with it." Essentially, a number of servers on
the Internet don't support TLS 1.1+. This is why web browsers
continue to support TLS 1.0 despite desires from security experts.

This patch changes Mercurial's default behavior on modern Python
versions to require TLS 1.1+, thus avoiding known security issues
with TLS 1.0 and making Mercurial more secure by default. Rather
than drop TLS 1.0 support wholesale, we still allow TLS 1.0 to be
used if configured. This is a compromise solution - ideally we'd
disallow TLS 1.0. However, since we're not sure how many Mercurial
servers don't support TLS 1.1+ and we're not sure how much user
inconvenience this change will bring, I think it is prudent to ship
an escape hatch that still allows usage of TLS 1.0. In the default
case our users get better security. In the worst case, they are no
worse off than before this patch.

This patch has no effect when running on Python versions that don't
support TLS 1.1+.

As the added test shows, connecting to a server that doesn't
support TLS 1.1+ will display a warning message with a link to
our wiki, where we can guide people to configure their client to
allow less secure connections.

  $ echo 'raise Exception("bit bucket overflow")' > badext.py
  $ abspathexc=`pwd`/badext.py

  $ cat >baddocext.py <<EOF
  > """
  > baddocext is bad
  > """
  > EOF
  $ abspathdoc=`pwd`/baddocext.py

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > gpg =
  > hgext.gpg =
  > badext = $abspathexc
  > baddocext = $abspathdoc
  > badext2 =
  > EOF

  $ hg -q help help 2>&1 |grep extension
  *** failed to import extension badext from $TESTTMP/badext.py: bit bucket overflow
  *** failed to import extension badext2: No module named badext2

show traceback

  $ hg -q help help --traceback 2>&1 | egrep ' extension|^Exception|Traceback|ImportError'
  *** failed to import extension badext from $TESTTMP/badext.py: bit bucket overflow
  Traceback (most recent call last):
  Exception: bit bucket overflow
  *** failed to import extension badext2: No module named badext2
  Traceback (most recent call last):
  ImportError: No module named badext2

names of extensions failed to load can be accessed via extensions.notloaded()

  $ cat <<EOF > showbadexts.py
  > from mercurial import cmdutil, commands, extensions
  > cmdtable = {}
  > command = cmdutil.command(cmdtable)
  > @command('showbadexts', norepo=True)
  > def showbadexts(ui, *pats, **opts):
  >     ui.write('BADEXTS: %s\n' % ' '.join(sorted(extensions.notloaded())))
  > EOF
  $ hg --config extensions.badexts=showbadexts.py showbadexts 2>&1 | grep '^BADEXTS'
  BADEXTS: badext badext2

show traceback for ImportError of hgext.name if debug is set
(note that --debug option isn't applied yet when loading extensions)

  $ (hg -q help help --traceback --config ui.debug=True 2>&1) \
  > | grep -v '^ ' \
  > | egrep 'extension..[^p]|^Exception|Traceback|ImportError|not import'
  *** failed to import extension badext from $TESTTMP/badext.py: bit bucket overflow
  Traceback (most recent call last):
  Exception: bit bucket overflow
  could not import hgext.badext2 (No module named *badext2): trying badext2 (glob)
  Traceback (most recent call last):
  ImportError: No module named *badext2 (glob)
  could not import hgext3rd.badext2 (No module named *badext2): trying badext2 (glob)
  Traceback (most recent call last):
  ImportError: No module named *badext2 (glob)
  *** failed to import extension badext2: No module named badext2
  Traceback (most recent call last):
  ImportError: No module named badext2

confirm that there's no crash when an extension's documentation is bad

  $ hg help --keyword baddocext
  *** failed to import extension badext from $TESTTMP/badext.py: bit bucket overflow
  *** failed to import extension badext2: No module named badext2
  Topics:
  
   extensions Using Additional Features