view tests/test-win32text.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.

  $ hg init t
  $ cd t
  $ cat > unix2dos.py <<EOF
  > import sys
  > 
  > for path in sys.argv[1:]:
  >     data = file(path, 'rb').read()
  >     data = data.replace('\n', '\r\n')
  >     file(path, 'wb').write(data)
  > EOF
  $ echo '[hooks]' >> .hg/hgrc
  $ echo 'pretxncommit.crlf = python:hgext.win32text.forbidcrlf' >> .hg/hgrc
  $ echo 'pretxnchangegroup.crlf = python:hgext.win32text.forbidcrlf' >> .hg/hgrc
  $ cat .hg/hgrc
  [hooks]
  pretxncommit.crlf = python:hgext.win32text.forbidcrlf
  pretxnchangegroup.crlf = python:hgext.win32text.forbidcrlf

  $ echo hello > f
  $ hg add f

commit should succeed

  $ hg ci -m 1

  $ hg clone . ../zoz
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cp .hg/hgrc ../zoz/.hg
  $ $PYTHON unix2dos.py f

commit should fail

  $ hg ci -m 2.1
  attempt to commit or push text file(s) using CRLF line endings
  in f583ea08d42a: f
  transaction abort!
  rollback completed
  abort: pretxncommit.crlf hook failed
  [255]

  $ mv .hg/hgrc .hg/hgrc.bak

commits should succeed

  $ hg ci -m 2
  $ hg cp f g
  $ hg ci -m 2.2

push should fail

  $ hg push ../zoz
  pushing to ../zoz
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  attempt to commit or push text file(s) using CRLF line endings
  in bc2d09796734: g
  in b1aa5cde7ff4: f
  
  To prevent this mistake in your local repository,
  add to Mercurial.ini or .hg/hgrc:
  
  [hooks]
  pretxncommit.crlf = python:hgext.win32text.forbidcrlf
  
  and also consider adding:
  
  [extensions]
  win32text =
  [encode]
  ** = cleverencode:
  [decode]
  ** = cleverdecode:
  transaction abort!
  rollback completed
  abort: pretxnchangegroup.crlf hook failed
  [255]

  $ mv .hg/hgrc.bak .hg/hgrc
  $ echo hello > f
  $ hg rm g

commit should succeed

  $ hg ci -m 2.3

push should succeed

  $ hg push ../zoz
  pushing to ../zoz
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files

and now for something completely different

  $ mkdir d
  $ echo hello > d/f2
  $ $PYTHON unix2dos.py d/f2
  $ hg add d/f2
  $ hg ci -m 3
  attempt to commit or push text file(s) using CRLF line endings
  in 053ba1a3035a: d/f2
  transaction abort!
  rollback completed
  abort: pretxncommit.crlf hook failed
  [255]
  $ hg revert -a
  forgetting d/f2
  $ rm d/f2

  $ hg rem f
  $ hg ci -m 4

  $ $PYTHON -c 'file("bin", "wb").write("hello\x00\x0D\x0A")'
  $ hg add bin
  $ hg ci -m 5
  $ hg log -v
  changeset:   5:f0b1c8d75fce
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       bin
  description:
  5
  
  
  changeset:   4:77796dbcd4ad
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       f
  description:
  4
  
  
  changeset:   3:7c1b5430b350
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       f g
  description:
  2.3
  
  
  changeset:   2:bc2d09796734
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       g
  description:
  2.2
  
  
  changeset:   1:b1aa5cde7ff4
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       f
  description:
  2
  
  
  changeset:   0:fcf06d5c4e1d
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       f
  description:
  1
  
  
  $ hg clone . dupe
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ for x in a b c d; do echo content > dupe/$x; done
  $ hg -R dupe add
  adding dupe/a
  adding dupe/b
  adding dupe/c
  adding dupe/d
  $ $PYTHON unix2dos.py dupe/b dupe/c dupe/d
  $ hg -R dupe ci -m a dupe/a
  $ hg -R dupe ci -m b/c dupe/[bc]
  $ hg -R dupe ci -m d dupe/d
  $ hg -R dupe log -v
  changeset:   8:67ac5962ab43
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       d
  description:
  d
  
  
  changeset:   7:68c127d1834e
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       b c
  description:
  b/c
  
  
  changeset:   6:adbf8bf7f31d
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       a
  description:
  a
  
  
  changeset:   5:f0b1c8d75fce
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       bin
  description:
  5
  
  
  changeset:   4:77796dbcd4ad
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       f
  description:
  4
  
  
  changeset:   3:7c1b5430b350
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       f g
  description:
  2.3
  
  
  changeset:   2:bc2d09796734
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       g
  description:
  2.2
  
  
  changeset:   1:b1aa5cde7ff4
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       f
  description:
  2
  
  
  changeset:   0:fcf06d5c4e1d
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       f
  description:
  1
  
  
  $ hg pull dupe
  pulling from dupe
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 4 changes to 4 files
  attempt to commit or push text file(s) using CRLF line endings
  in 67ac5962ab43: d
  in 68c127d1834e: b
  in 68c127d1834e: c
  
  To prevent this mistake in your local repository,
  add to Mercurial.ini or .hg/hgrc:
  
  [hooks]
  pretxncommit.crlf = python:hgext.win32text.forbidcrlf
  
  and also consider adding:
  
  [extensions]
  win32text =
  [encode]
  ** = cleverencode:
  [decode]
  ** = cleverdecode:
  transaction abort!
  rollback completed
  abort: pretxnchangegroup.crlf hook failed
  [255]

  $ hg log -v
  changeset:   5:f0b1c8d75fce
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       bin
  description:
  5
  
  
  changeset:   4:77796dbcd4ad
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       f
  description:
  4
  
  
  changeset:   3:7c1b5430b350
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       f g
  description:
  2.3
  
  
  changeset:   2:bc2d09796734
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       g
  description:
  2.2
  
  
  changeset:   1:b1aa5cde7ff4
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       f
  description:
  2
  
  
  changeset:   0:fcf06d5c4e1d
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       f
  description:
  1
  
  
  $ rm .hg/hgrc
  $ (echo some; echo text) > f3
  $ $PYTHON -c 'file("f4.bat", "wb").write("rem empty\x0D\x0A")'
  $ hg add f3 f4.bat
  $ hg ci -m 6
  $ cat bin
  hello\x00\r (esc)
  $ cat f3
  some
  text
  $ cat f4.bat
  rem empty\r (esc)

  $ echo '[extensions]' >> .hg/hgrc
  $ echo 'win32text = ' >> .hg/hgrc
  $ echo '[decode]' >> .hg/hgrc
  $ echo '** = cleverdecode:' >> .hg/hgrc
  $ echo '[encode]' >> .hg/hgrc
  $ echo '** = cleverencode:' >> .hg/hgrc
  $ cat .hg/hgrc
  [extensions]
  win32text = 
  [decode]
  ** = cleverdecode:
  [encode]
  ** = cleverencode:

Trigger deprecation warning:

  $ hg id -t
  win32text is deprecated: https://mercurial-scm.org/wiki/Win32TextExtension
  tip

Disable warning:

  $ echo '[win32text]' >> .hg/hgrc
  $ echo 'warn = no' >> .hg/hgrc
  $ hg id -t
  tip

  $ rm f3 f4.bat bin
  $ hg co -C
  WARNING: f4.bat already has CRLF line endings
  and does not need EOL conversion by the win32text plugin.
  Before your next commit, please reconsider your encode/decode settings in 
  Mercurial.ini or $TESTTMP/t/.hg/hgrc.
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat bin
  hello\x00\r (esc)
  $ cat f3
  some\r (esc)
  text\r (esc)
  $ cat f4.bat
  rem empty\r (esc)

  $ $PYTHON -c 'file("f5.sh", "wb").write("# empty\x0D\x0A")'
  $ hg add f5.sh
  $ hg ci -m 7
  $ cat f5.sh
  # empty\r (esc)
  $ hg cat f5.sh
  # empty
  $ echo '% just linefeed' > linefeed
  $ hg ci -qAm 8 linefeed
  $ cat linefeed
  % just linefeed
  $ hg cat linefeed
  % just linefeed
  $ hg st -q
  $ hg revert -a linefeed
  no changes needed to linefeed
  $ cat linefeed
  % just linefeed
  $ hg st -q
  $ echo modified >> linefeed
  $ hg st -q
  M linefeed
  $ hg revert -a
  reverting linefeed
  $ hg st -q
  $ cat linefeed
  % just linefeed\r (esc)

  $ cd ..