view tests/test-lfs-serve.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.

#testcases lfsremote-on lfsremote-off
#require serve

This test splits `hg serve` with and without using the extension into separate
tests cases.  The tests are broken down as follows, where "LFS"/"No-LFS"
indicates whether or not there are commits that use an LFS file, and "D"/"E"
indicates whether or not the extension is loaded.  The "X" cases are not tested
individually, because the lfs requirement causes the process to bail early if
the extension is disabled.

.                        Server
.
.                    No-LFS        LFS
.            +----------------------------+
.            |   ||  D  |  E  |  D  |  E  |
.            |---++=======================|
.  C         | D || N/A | #1  |  X  | #4  |
.  l    No   +---++-----------------------|
.  i    LFS  | E || #2  | #2  |  X  | #5  |
.  e         +---++-----------------------|
.  n         | D ||  X  |  X  |  X  |  X  |
.  t    LFS  |---++-----------------------|
.            | E || #3  | #3  |  X  | #6  |
.            |---++-----------------------+

  $ hg init server
  $ SERVER_REQUIRES="$TESTTMP/server/.hg/requires"

Skip the experimental.changegroup3=True config.  Failure to agree on this comes
first, and causes a "ValueError: no common changegroup version" or "abort:
HTTP Error 500: Internal Server Error", if the extension is only loaded on one
side.  If that *is* enabled, the subsequent failure is "abort: missing processor
for flag '0x2000'!" if the extension is only loaded on one side (possibly also
masked by the Internal Server Error message).
  $ cat >> $HGRCPATH <<EOF
  > [lfs]
  > url=file:$TESTTMP/dummy-remote/
  > threshold=10
  > [web]
  > allow_push=*
  > push_ssl=False
  > EOF

#if lfsremote-on
  $ hg --config extensions.lfs= -R server \
  >    serve -p $HGPORT -d --pid-file=hg.pid --errorlog=$TESTTMP/errors.log
#else
  $ hg --config extensions.lfs=! -R server \
  >    serve -p $HGPORT -d --pid-file=hg.pid --errorlog=$TESTTMP/errors.log
#endif

  $ cat hg.pid >> $DAEMON_PIDS
  $ hg clone -q http://localhost:$HGPORT client
  $ grep 'lfs' client/.hg/requires $SERVER_REQUIRES
  [1]

--------------------------------------------------------------------------------
Case #1: client with non-lfs content and the extension disabled; server with
non-lfs content, and the extension enabled.

  $ cd client
  $ echo 'non-lfs' > nonlfs.txt
  $ hg ci -Aqm 'non-lfs'
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  [1]

#if lfsremote-on

  $ hg push -q
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  [1]

  $ hg clone -q http://localhost:$HGPORT $TESTTMP/client1_clone
  $ grep 'lfs' $TESTTMP/client1_clone/.hg/requires $SERVER_REQUIRES
  [1]

  $ hg init $TESTTMP/client1_pull
  $ hg -R $TESTTMP/client1_pull pull -q http://localhost:$HGPORT
  $ grep 'lfs' $TESTTMP/client1_pull/.hg/requires $SERVER_REQUIRES
  [1]

  $ hg identify http://localhost:$HGPORT
  d437e1d24fbd

#endif

--------------------------------------------------------------------------------
Case #2: client with non-lfs content and the extension enabled; server with
non-lfs content, and the extension state controlled by #testcases.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > lfs =
  > EOF
  $ echo 'non-lfs' > nonlfs2.txt
  $ hg ci -Aqm 'non-lfs file with lfs client'

Since no lfs content has been added yet, the push is allowed, even when the
extension is not enabled remotely.

  $ hg push -q
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  [1]

  $ hg clone -q http://localhost:$HGPORT $TESTTMP/client2_clone
  $ grep 'lfs' $TESTTMP/client2_clone/.hg/requires $SERVER_REQUIRES
  [1]

  $ hg init $TESTTMP/client2_pull
  $ hg -R $TESTTMP/client2_pull pull -q http://localhost:$HGPORT
  $ grep 'lfs' $TESTTMP/client2_pull/.hg/requires $SERVER_REQUIRES
  [1]

  $ hg identify http://localhost:$HGPORT
  1477875038c6

--------------------------------------------------------------------------------
Case #3: client with lfs content and the extension enabled; server with
non-lfs content, and the extension state controlled by #testcases.  The server
should have an 'lfs' requirement after it picks up its first commit with a blob.

  $ echo 'this is a big lfs file' > lfs.bin
  $ hg ci -Aqm 'lfs'
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  .hg/requires:lfs

#if lfsremote-off
  $ hg push -q
  abort: required features are not supported in the destination: lfs
  (enable the lfs extension on the server)
  [255]
#else
  $ hg push -q
#endif
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  .hg/requires:lfs
  $TESTTMP/server/.hg/requires:lfs (lfsremote-on !)

  $ hg clone -q http://localhost:$HGPORT $TESTTMP/client3_clone
  $ grep 'lfs' $TESTTMP/client3_clone/.hg/requires $SERVER_REQUIRES || true
  $TESTTMP/client3_clone/.hg/requires:lfs (lfsremote-on !)
  $TESTTMP/server/.hg/requires:lfs (lfsremote-on !)

  $ hg init $TESTTMP/client3_pull
  $ hg -R $TESTTMP/client3_pull pull -q http://localhost:$HGPORT
  $ grep 'lfs' $TESTTMP/client3_pull/.hg/requires $SERVER_REQUIRES || true
  $TESTTMP/client3_pull/.hg/requires:lfs (lfsremote-on !)
  $TESTTMP/server/.hg/requires:lfs (lfsremote-on !)

The difference here is the push failed above when the extension isn't
enabled on the server.
  $ hg identify http://localhost:$HGPORT
  8374dc4052cb (lfsremote-on !)
  1477875038c6 (lfsremote-off !)

Don't bother testing the lfsremote-off cases- the server won't be able
to launch if there's lfs content and the extension is disabled.

#if lfsremote-on

--------------------------------------------------------------------------------
Case #4: client with non-lfs content and the extension disabled; server with
lfs content, and the extension enabled.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > lfs = !
  > EOF

  $ hg init $TESTTMP/client4
  $ cd $TESTTMP/client4
  $ cat >> .hg/hgrc <<EOF
  > [paths]
  > default = http://localhost:$HGPORT
  > EOF
  $ echo 'non-lfs' > nonlfs2.txt
  $ hg ci -Aqm 'non-lfs'
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  $TESTTMP/server/.hg/requires:lfs

  $ hg push -q --force
  warning: repository is unrelated
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  $TESTTMP/server/.hg/requires:lfs

TODO: fail more gracefully.

  $ hg clone -q http://localhost:$HGPORT $TESTTMP/client4_clone
  abort: HTTP Error 500: Internal Server Error
  [255]
  $ grep 'lfs' $TESTTMP/client4_clone/.hg/requires $SERVER_REQUIRES
  grep: $TESTTMP/client4_clone/.hg/requires: $ENOENT$
  $TESTTMP/server/.hg/requires:lfs
  [2]

TODO: fail more gracefully.

  $ hg init $TESTTMP/client4_pull
  $ hg -R $TESTTMP/client4_pull pull -q http://localhost:$HGPORT
  abort: HTTP Error 500: Internal Server Error
  [255]
  $ grep 'lfs' $TESTTMP/client4_pull/.hg/requires $SERVER_REQUIRES
  $TESTTMP/server/.hg/requires:lfs

  $ hg identify http://localhost:$HGPORT
  03b080fa9d93

--------------------------------------------------------------------------------
Case #5: client with non-lfs content and the extension enabled; server with
lfs content, and the extension enabled.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > lfs =
  > EOF
  $ echo 'non-lfs' > nonlfs3.txt
  $ hg ci -Aqm 'non-lfs file with lfs client'

  $ hg push -q
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  $TESTTMP/server/.hg/requires:lfs

  $ hg clone -q http://localhost:$HGPORT $TESTTMP/client5_clone
  $ grep 'lfs' $TESTTMP/client5_clone/.hg/requires $SERVER_REQUIRES
  $TESTTMP/client5_clone/.hg/requires:lfs
  $TESTTMP/server/.hg/requires:lfs

  $ hg init $TESTTMP/client5_pull
  $ hg -R $TESTTMP/client5_pull pull -q http://localhost:$HGPORT
  $ grep 'lfs' $TESTTMP/client5_pull/.hg/requires $SERVER_REQUIRES
  $TESTTMP/client5_pull/.hg/requires:lfs
  $TESTTMP/server/.hg/requires:lfs

  $ hg identify http://localhost:$HGPORT
  c729025cc5e3

--------------------------------------------------------------------------------
Case #6: client with lfs content and the extension enabled; server with
lfs content, and the extension enabled.

  $ echo 'this is another lfs file' > lfs2.txt
  $ hg ci -Aqm 'lfs file with lfs client'

  $ hg push -q
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  .hg/requires:lfs
  $TESTTMP/server/.hg/requires:lfs

  $ hg clone -q http://localhost:$HGPORT $TESTTMP/client6_clone
  $ grep 'lfs' $TESTTMP/client6_clone/.hg/requires $SERVER_REQUIRES
  $TESTTMP/client6_clone/.hg/requires:lfs
  $TESTTMP/server/.hg/requires:lfs

  $ hg init $TESTTMP/client6_pull
  $ hg -R $TESTTMP/client6_pull pull -q http://localhost:$HGPORT
  $ grep 'lfs' $TESTTMP/client6_pull/.hg/requires $SERVER_REQUIRES
  $TESTTMP/client6_pull/.hg/requires:lfs
  $TESTTMP/server/.hg/requires:lfs

  $ hg identify http://localhost:$HGPORT
  d3b84d50eacb

--------------------------------------------------------------------------------
Misc: process dies early if a requirement exists and the extension is disabled

  $ hg --config extensions.lfs=! summary
  abort: repository requires features unknown to this Mercurial: lfs!
  (see https://mercurial-scm.org/wiki/MissingRequirement for more information)
  [255]

#endif

  $ $PYTHON $TESTDIR/killdaemons.py $DAEMON_PIDS

#if lfsremote-on
  $ cat $TESTTMP/errors.log | grep '^[A-Z]'
  Traceback (most recent call last):
  ValueError: no common changegroup version
  Traceback (most recent call last):
  ValueError: no common changegroup version
#else
  $ cat $TESTTMP/errors.log
#endif