view tests/test-convert-tla.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.

#require tla symlink

  $ tla my-id "mercurial <[e-mail]>"
  $ echo "[extensions]" >> $HGRCPATH
  $ echo "convert=" >> $HGRCPATH

create tla archive

  $ tla make-archive tla@mercurial--convert `pwd`/hg-test-convert-tla

initialize tla repo

  $ mkdir tla-repo
  $ cd tla-repo/
  $ tla init-tree tla@mercurial--convert/tla--test--0
  $ tla import
  * creating version tla@mercurial--convert/tla--test--0
  * imported tla@mercurial--convert/tla--test--0

create initial files

  $ echo 'this is a file' > a
  $ tla add a
  $ mkdir src
  $ tla add src
  $ cd src
  $ dd count=1 if=/dev/zero of=b > /dev/null 2> /dev/null
  $ tla add b
  $ tla commit -s "added a file, src and src/b (binary)"
  A/ .arch-ids
  A/ src
  A/ src/.arch-ids
  A  .arch-ids/a.id
  A  a
  A  src/.arch-ids/=id
  A  src/.arch-ids/b.id
  A  src/b
  * update pristine tree (tla@mercurial--convert/tla--test--0--base-0 => tla--test--0--patch-1)
  * committed tla@mercurial--convert/tla--test--0--patch-1

create link file and modify a

  $ ln -s ../a a-link
  $ tla add a-link
  $ echo 'this a modification to a' >> ../a
  $ tla commit -s "added link to a and modify a"
  A  src/.arch-ids/a-link.id
  A  src/a-link
  M  a
  * update pristine tree (tla@mercurial--convert/tla--test--0--patch-1 => tla--test--0--patch-2)
  * committed tla@mercurial--convert/tla--test--0--patch-2

create second link and modify b

  $ ln -s ../a a-link-2
  $ tla add a-link-2
  $ dd count=1 seek=1 if=/dev/zero of=b > /dev/null 2> /dev/null
  $ tla commit -s "added second link and modify b"
  A  src/.arch-ids/a-link-2.id
  A  src/a-link-2
  Mb src/b
  * update pristine tree (tla@mercurial--convert/tla--test--0--patch-2 => tla--test--0--patch-3)
  * committed tla@mercurial--convert/tla--test--0--patch-3

b file to link and a-link-2 to regular file

  $ rm -f a-link-2
  $ echo 'this is now a regular file' > a-link-2
  $ ln -sf ../a b
  $ tla commit -s "file to link and link to file test"
  fl src/b
  lf src/a-link-2
  * update pristine tree (tla@mercurial--convert/tla--test--0--patch-3 => tla--test--0--patch-4)
  * committed tla@mercurial--convert/tla--test--0--patch-4

move a-link-2 file and src directory

  $ cd ..
  $ tla mv src/a-link-2 c
  $ tla mv src test
  $ tla commit -s "move and rename a-link-2 file and src directory"
  D/ src/.arch-ids
  A/ test/.arch-ids
  /> src	test
  => src/.arch-ids/a-link-2.id	.arch-ids/c.id
  => src/a-link-2	c
  => src/.arch-ids/=id	test/.arch-ids/=id
  => src/.arch-ids/a-link.id	test/.arch-ids/a-link.id
  => src/.arch-ids/b.id	test/.arch-ids/b.id
  * update pristine tree (tla@mercurial--convert/tla--test--0--patch-4 => tla--test--0--patch-5)
  * committed tla@mercurial--convert/tla--test--0--patch-5
  $ cd ..

converting tla repo to Mercurial

  $ hg convert tla-repo tla-repo-hg
  initializing destination tla-repo-hg repository
  analyzing tree version tla@mercurial--convert/tla--test--0...
  scanning source...
  sorting...
  converting...
  5 initial import
  4 added a file, src and src/b (binary)
  3 added link to a and modify a
  2 added second link and modify b
  1 file to link and link to file test
  0 move and rename a-link-2 file and src directory
  $ tla register-archive -d tla@mercurial--convert
  $ glog()
  > {
  >     hg log -G --template '{rev} "{desc|firstline}" files: {files}\n' "$@"
  > }

show graph log

  $ glog -R tla-repo-hg
  o  5 "move and rename a-link-2 file and src directory" files: c src/a-link src/a-link-2 src/b test/a-link test/b
  |
  o  4 "file to link and link to file test" files: src/a-link-2 src/b
  |
  o  3 "added second link and modify b" files: src/a-link-2 src/b
  |
  o  2 "added link to a and modify a" files: a src/a-link
  |
  o  1 "added a file, src and src/b (binary)" files: a src/b
  |
  o  0 "initial import" files:
  
  $ hg up -q -R tla-repo-hg
  $ hg -R tla-repo-hg manifest --debug
  c4072c4b72e1cabace081888efa148ee80ca3cbb 644   a
  0201ac32a3a8e86e303dff60366382a54b48a72e 644   c
  c0067ba5ff0b7c9a3eb17270839d04614c435623 644 @ test/a-link
  375f4263d86feacdea7e3c27100abd1560f2a973 644 @ test/b