view tests/test-committer.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.

  $ unset HGUSER
  $ EMAIL="My Name <[e-mail]>"
  $ export EMAIL

  $ hg init test
  $ cd test
  $ touch asdf
  $ hg add asdf
  $ hg commit -m commit-1
  $ hg tip
  changeset:   0:53f268a58230
  tag:         tip
  user:        My Name <[e-mail]>
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     commit-1
  

  $ unset EMAIL
  $ echo 1234 > asdf
  $ hg commit -u "[e-mail]" -m commit-1
  $ hg tip
  changeset:   1:3871b2a9e9bf
  tag:         tip
  user:        [e-mail]
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     commit-1
  
  $ echo "[ui]" >> .hg/hgrc
  $ echo "username = foobar <[e-mail]>" >> .hg/hgrc
  $ echo 12 > asdf
  $ hg commit -m commit-1
  $ hg tip
  changeset:   2:8eeac6695c1c
  tag:         tip
  user:        foobar <[e-mail]>
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     commit-1
  
  $ echo 1 > asdf
  $ hg commit -u "[e-mail]" -m commit-1
  $ hg tip
  changeset:   3:957606a725e4
  tag:         tip
  user:        [e-mail]
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     commit-1
  
  $ echo 123 > asdf
  $ echo "[ui]" > .hg/hgrc
  $ echo "username = " >> .hg/hgrc
  $ hg commit -m commit-1
  abort: no username supplied
  (use 'hg config --edit' to set your username)
  [255]

# test alternate config var

  $ echo 1234 > asdf
  $ echo "[ui]" > .hg/hgrc
  $ echo "user = Foo Bar II <[e-mail]>" >> .hg/hgrc
  $ hg commit -m commit-1
  $ hg tip
  changeset:   4:6f24bfb4c617
  tag:         tip
  user:        Foo Bar II <[e-mail]>
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     commit-1
  
# test prompt username

  $ cat > .hg/hgrc <<EOF
  > [ui]
  > askusername = True
  > EOF

  $ echo 12345 > asdf
  $ hg commit --config ui.interactive=False -m ask
  enter a commit username: 
  no username found, using '[^']*' instead (re)
  $ hg rollback -q

  $ hg commit --config ui.interactive=True -m ask <<EOF
  > Asked User <[e-mail]>
  > EOF
  enter a commit username: Asked User <[e-mail]>
  $ hg tip
  changeset:   5:84c91d963b70
  tag:         tip
  user:        Asked User <[e-mail]>
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     ask
  

# test no .hg/hgrc (uses generated non-interactive username)

  $ echo space > asdf
  $ rm .hg/hgrc
  $ hg commit -m commit-1 2>&1
  no username found, using '[^']*' instead (re)

  $ echo space2 > asdf
  $ hg commit -u ' ' -m commit-1
  transaction abort!
  rollback completed
  abort: empty username!
  [255]

# don't add tests here, previous test is unstable

  $ cd ..