xdiff: remove whitespace related feature
In Mercurial, whitespace related handling are done at a higher level than
the low-level diff algorithm so "ignore spaces". So it's not used by mdiff.
Some of the upcoming optimizations would be more difficult with whitespace
related features kept. So let's remove them.
Differential Revision: https://phab.mercurial-scm.org/D2683
merge with stable
There were a handful of merge conflicts in the wire protocol code due
to significant refactoring in default. When resolving the conflicts,
I tried to produce the minimal number of changes to make the incoming
security patches work with the new code.
I will send some follow-up commits to get the security patches better
integrated into default.
Added signature for changeset
8bba684efde7
Added tag 4.5.2 for changeset
8bba684efde7
hgweb: always perform permissions checks on protocol commands (BC) (SEC)
Previously, the HTTP request handling code would only perform
permissions checking on a wire protocol command if that wire protocol
command defined its permissions / operation type. This meant that
commands (possibly provided by extensions) not defining their
operation type would bypass permissions check. This could lead
to exfiltration of data from servers and mutating repositories that
were supposed to be read-only.
This security issue has been present since the permissions table
was introduced by
d3147b4e3e8a in 2008.
This commit changes the behavior of the HTTP server to always
perform permissions checking for protocol requests. If an
explicit permission for a wire protocol command is not defined,
the server assumes the command can be used for writing and
governs access accordingly.
.. bc::
Wire protocol commands not defining their operation type in
``wireproto.PERMISSIONS`` are now assumed to be used for
"push" operations and access control to run those commands
is now enforced accordingly.
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.
wireproto: declare operation type for most commands (BC) (SEC)
The permissions model of hgweb relies on a dictionary to declare
the operation associated with each command - either "pull" or
"push." This dictionary was established by
d3147b4e3e8a in 2008.
Unfortunately, we neglected to update this dictionary as new
wire protocol commands were introduced.
This commit defines the operations of most wire protocol commands
in the permissions dictionary. The "batch" command is omitted because
it is special and requires a more complex solution.
Since permissions checking is skipped unless a command has an entry in
this dictionary (this security issue will be addressed in a subsequent
commit), the practical effect of this change is that various wire
protocol commands now HTTP 401 if web.deny_read or web.allow-pull,
etc are set to deny access. This is reflected by test changes. Note
how various `hg pull` and `hg push` operations now fail before
discovery. (They fail during the initial "capabilities" request.)
This change fixes a security issue where built-in wire protocol
commands would return repository data even if the web config were
configured to deny access to that data.
I'm on the fence as to whether we should HTTP 401 the capabilities
request. On one hand, it can expose repository metadata and can tell
callers things like what version of Mercurial the server is running.
On the other hand, a client may need to know the capabilities in order
to authenticate in a follow-up request. It appears that Mercurial
clients handle the HTTP 401 on *any* protocol request, so we should
be OK sending a 401 for "capabilities." But if this causes problems,
it should be possible to allow "capabilities" to always work.
.. bc::
Various read-only wire protocol commands now return HTTP 401
Unauthorized if the hgweb configuration denies read/pull access to
the repository.
Previously, various wire protocol commands would still work and
return data if read access was disabled.
wireproto: move command permissions dict out of hgweb_mod
The operation type associated with wire protocol commands is supposed
to be defined in a dictionary so it can be used for permissions
checking.
Since this metadata is closely associated with wire protocol commands
themselves, it makes sense to define it in the same module where
wire protocol commands are defined.
This commit moves hgweb_mod.perms to wireproto.PERMISSIONS and
updates most references in the code to use the new home. The old
symbol remains an alias for the new symbol. Tests pass with the
code pointing at the old symbol. So this should be API compatible
for extensions.
As part of the code move, we split up the assignment to the dict
so it is next to the @wireprotocommand. This reinforces that a
@wireprotocommand should have an entry in this dict.
In the future, we'll want to declare permissions as part of the
@wireprotocommand decorator. But this isn't appropriate for the
stable branch.
tests: comprehensively test HTTP server permissions checking
We didn't have test coverage for numerous web.* config options. We
add that test coverage.
Included in the tests are tests for custom commands. We have commands
that are supposedly read-only and perform writes and a variation of
each that does and does not define its operation type in
hgweb_mod.perms.
The tests reveal a handful of security bugs related to permissions
checking. Subsequent commits will address these security bugs.