view tests/test-rebase-mq-skip.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.

This emulates the effects of an hg pull --rebase in which the remote repo
already has one local mq patch

  $ cat >> $HGRCPATH <<EOF
  > [format]
  > usegeneraldelta=yes
  > [extensions]
  > rebase=
  > mq=
  > 
  > [phases]
  > publish=False
  > 
  > [alias]
  > tglog = log -G --template "{rev}: {node|short} '{desc}' tags: {tags}\n"
  > EOF


  $ hg init a
  $ cd a
  $ hg qinit -c

  $ echo c1 > c1
  $ hg add c1
  $ hg ci -m C1

  $ echo r1 > r1
  $ hg add r1
  $ hg ci -m R1

  $ hg up -q 0

  $ hg qnew p0.patch -d '1 0'
  $ echo p0 > p0
  $ hg add p0
  $ hg qref -m P0

  $ hg qnew p1.patch -d '2 0'
  $ echo p1 > p1
  $ hg add p1
  $ hg qref -m P1

  $ hg export qtip > p1.patch

  $ hg up -q -C 1

  $ hg import p1.patch
  applying p1.patch

  $ rm p1.patch

  $ hg up -q -C qtip

  $ hg rebase -v
  rebasing 2:13a46ce44f60 "P0" (p0.patch qbase)
  resolving manifests
  removing p0
  getting r1
  resolving manifests
  getting p0
  committing files:
  p0
  committing manifest
  committing changelog
  rebasing 3:148775c71080 "P1" (p1.patch qtip)
  resolving manifests
  note: rebase of 3:148775c71080 created no changes to commit
  rebase merging completed
  updating mq patch p0.patch to 5:9ecc820b1737
  $TESTTMP/a/.hg/patches/p0.patch
  2 changesets found
  uncompressed size of bundle content:
       348 (changelog)
       324 (manifests)
       129  p0
       129  p1
  saved backup bundle to $TESTTMP/a/.hg/strip-backup/13a46ce44f60-5da6ecfb-rebase.hg
  2 changesets found
  uncompressed size of bundle content:
       403 (changelog)
       324 (manifests)
       129  p0
       129  p1
  adding branch
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  rebase completed
  1 revisions have been skipped

  $ hg tglog
  @  3: 9ecc820b1737 'P0' tags: p0.patch qbase qtip tip
  |
  o  2: 869d8b134a27 'P1' tags: qparent
  |
  o  1: da108f2755df 'R1' tags:
  |
  o  0: cd320d50b341 'C1' tags:
  
  $ cd ..


  $ hg init b
  $ cd b
  $ hg qinit -c

  $ for i in r0 r1 r2 r3 r4 r5 r6;
  > do
  >     echo $i > $i
  >     hg ci -Am $i
  > done
  adding r0
  adding r1
  adding r2
  adding r3
  adding r4
  adding r5
  adding r6

  $ hg qimport -r 1:tip

  $ hg up -q 0

  $ for i in r1 r3 r7 r8;
  > do
  >     echo $i > $i
  >     hg ci -Am branch2-$i
  > done
  adding r1
  created new head
  adding r3
  adding r7
  adding r8

  $ echo somethingelse > r4
  $ hg ci -Am branch2-r4
  adding r4

  $ echo r6 > r6
  $ hg ci -Am branch2-r6
  adding r6

  $ hg up -q qtip

  $ HGMERGE=internal:fail hg rebase
  rebasing 1:b4bffa6e4776 "r1" (qbase r1)
  note: rebase of 1:b4bffa6e4776 created no changes to commit
  rebasing 2:c0fd129beb01 "r2" (r2)
  rebasing 3:6ff5b8feed8e "r3" (r3)
  note: rebase of 3:6ff5b8feed8e created no changes to commit
  rebasing 4:094320fec554 "r4" (r4)
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

  $ HGMERGE=internal:local hg resolve --all
  (no more unresolved files)
  continue: hg rebase --continue

  $ hg rebase --continue
  already rebased 1:b4bffa6e4776 "r1" (qbase r1) as 057f55ff8f44
  already rebased 2:c0fd129beb01 "r2" (r2) as 1660ab13ce9a
  already rebased 3:6ff5b8feed8e "r3" (r3) as 1660ab13ce9a
  rebasing 4:094320fec554 "r4" (r4)
  note: rebase of 4:094320fec554 created no changes to commit
  rebasing 5:681a378595ba "r5" (r5)
  rebasing 6:512a1f24768b "r6" (qtip r6)
  note: rebase of 6:512a1f24768b created no changes to commit
  saved backup bundle to $TESTTMP/b/.hg/strip-backup/b4bffa6e4776-b9bfb84d-rebase.hg

  $ hg tglog
  @  8: 0b9735ce8f0a 'r5' tags: qtip r5 tip
  |
  o  7: 1660ab13ce9a 'r2' tags: qbase r2
  |
  o  6: 057f55ff8f44 'branch2-r6' tags: qparent
  |
  o  5: 1d7287f8deb1 'branch2-r4' tags:
  |
  o  4: 3c10b9db2bd5 'branch2-r8' tags:
  |
  o  3: b684023158dc 'branch2-r7' tags:
  |
  o  2: d817754b1251 'branch2-r3' tags:
  |
  o  1: 0621a206f8a4 'branch2-r1' tags:
  |
  o  0: 222799e2f90b 'r0' tags:
  

  $ cd ..