view tests/test-journal-share.t @ 36755:ff4bc0ab6740 stable

wireproto: check permissions when executing "batch" command (BC) (SEC)

For as long as the "batch" command has existed (introduced by
bd88561afb4b and first released as part of Mercurial 1.9), that command
(like most wire commands introduced after 2008) lacked an entry in
the hgweb permissions table. And since we don't verify permissions if
an entry is missing from the permissions table, this meant that
executing a command via "batch" would bypass all permissions
checks.

The security implications are significant: a Mercurial HTTP server
would allow writes via "batch" wire protocol commands as long as
the HTTP request were processed by Mercurial and the process running
the Mercurial HTTP server had write access to the repository. The
Mercurial defaults of servers being read-only and the various web.*
config options to define access control were bypassed.

In addition, "batch" could be used to exfiltrate data from servers
that were configured to not allow read access.

Both forms of permissions bypass could be mitigated to some extent
by using HTTP authentication. This would prevent HTTP requests from
hitting Mercurial's server logic. However, any authenticated request
would still be able to bypass permissions checks via "batch" commands.

The easiest exploit was to send "pushkey" commands via "batch" and
modify the state of bookmarks, phases, and obsolescence markers.
However, I suspect a well-crafted HTTP request could trick the server
into running the "unbundle" wire protocol command, effectively
performing a full `hg push` to create new changesets on the remote.

This commit plugs this gaping security hole by having the "batch"
command perform permissions checking on each sub-command that is
being batched. We do this by threading a permissions checking
callable all the way to the protocol handler. The threading is a
bit hacky from a code perspective. But it preserves API compatibility,
which is the proper thing to do on the stable branch.

One of the subtle things we do is assume that a command with an
undefined permission is a "push" command. This is the safest thing to
do from a security perspective: we don't want to take chances that
a command could perform a write even though the server is configured
to not allow writes.

As the test changes demonstrate, it is no longer possible to bypass
permissions via the "batch" wire protocol command.

.. bc::

   The "batch" wire protocol command now enforces permissions of
   each invoked sub-command. Wire protocol commands must define
   their operation type or the "batch" command will assume they
   can write data and will prevent their execution on HTTP servers
   unless the HTTP request method is POST, the server is configured
   to allow pushes, and the (possibly authenticated) HTTP user is
   authorized to perform a push.

Journal extension test: tests the share extension support

  $ cat >> testmocks.py << EOF
  > # mock out util.getuser() and util.makedate() to supply testable values
  > import os
  > from mercurial import util
  > def mockgetuser():
  >     return 'foobar'
  > 
  > def mockmakedate():
  >     filename = os.path.join(os.environ['TESTTMP'], 'testtime')
  >     try:
  >         with open(filename, 'rb') as timef:
  >             time = float(timef.read()) + 1
  >     except IOError:
  >         time = 0.0
  >     with open(filename, 'wb') as timef:
  >         timef.write(str(time))
  >     return (time, 0)
  > 
  > util.getuser = mockgetuser
  > util.makedate = mockmakedate
  > EOF

  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > journal=
  > share=
  > testmocks=`pwd`/testmocks.py
  > [remotenames]
  > rename.default=remote
  > EOF

  $ hg init repo
  $ cd repo
  $ hg bookmark bm
  $ touch file0
  $ hg commit -Am file0-added
  adding file0
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         commit -Am file0-added
  0fd3805711f9  bm        commit -Am file0-added

A shared working copy initially receives the same bookmarks and working copy

  $ cd ..
  $ hg share repo shared1
  updating working directory
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd shared1
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         share repo shared1

unless you explicitly share bookmarks

  $ cd ..
  $ hg share --bookmarks repo shared2
  updating working directory
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd shared2
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         share --bookmarks repo shared2
  0fd3805711f9  bm        commit -Am file0-added

Moving the bookmark in the original repository is only shown in the repository
that shares bookmarks

  $ cd ../repo
  $ touch file1
  $ hg commit -Am file1-added
  adding file1
  $ cd ../shared1
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         share repo shared1
  $ cd ../shared2
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  4f354088b094  bm        commit -Am file1-added
  0fd3805711f9  .         share --bookmarks repo shared2
  0fd3805711f9  bm        commit -Am file0-added

But working copy changes are always 'local'

  $ cd ../repo
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (leaving bookmark bm)
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         up 0
  4f354088b094  .         commit -Am file1-added
  4f354088b094  bm        commit -Am file1-added
  0fd3805711f9  .         commit -Am file0-added
  0fd3805711f9  bm        commit -Am file0-added
  $ cd ../shared2
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  4f354088b094  bm        commit -Am file1-added
  0fd3805711f9  .         share --bookmarks repo shared2
  0fd3805711f9  bm        commit -Am file0-added
  $ hg up tip
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg journal
  previous locations of '.':
  0fd3805711f9  up 0
  4f354088b094  up tip
  0fd3805711f9  share --bookmarks repo shared2

Unsharing works as expected; the journal remains consistent

  $ cd ../shared1
  $ hg unshare
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         share repo shared1
  $ cd ../shared2
  $ hg unshare
  $ hg journal --all
  previous locations of the working copy and bookmarks:
  0fd3805711f9  .         up 0
  4f354088b094  .         up tip
  4f354088b094  bm        commit -Am file1-added
  0fd3805711f9  .         share --bookmarks repo shared2
  0fd3805711f9  bm        commit -Am file0-added

New journal entries in the source repo no longer show up in the other working copies

  $ cd ../repo
  $ hg bookmark newbm -r tip
  $ hg journal newbm
  previous locations of 'newbm':
  4f354088b094  bookmark newbm -r tip
  $ cd ../shared2
  $ hg journal newbm
  previous locations of 'newbm':
  no recorded locations

This applies for both directions

  $ hg bookmark shared2bm -r tip
  $ hg journal shared2bm
  previous locations of 'shared2bm':
  4f354088b094  bookmark shared2bm -r tip
  $ cd ../repo
  $ hg journal shared2bm
  previous locations of 'shared2bm':
  no recorded locations