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Differential D2719

wireproto: formalize permissions checking as part of protocol interface
ClosedPublic

Authored by indygreg on Mar 7 2018, 7:24 PM.

Details

Reviewers
durin42
Group Reviewers
hg-reviewers
Commits
rHG66de4555cefd: wireproto: formalize permissions checking as part of protocol interface
Summary

Per the inline comment desiring to formalize permissions checking
in the protocol interface, we do that.

I'm not convinced this is the best way to go about things. I would love
for there to e.g. be a better exception for denoting permissions
problems. But it does feel strictly better than snipping attributes
on the proto instance.

Diff Detail

Repository
rHG Mercurial
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Revision Contents
Changeset List

Diff 6773

mercurial/hgweb/hgweb_mod.py

parts = parts[len(repo_parts):] parts = parts[len(repo_parts):]
query = '/'.join(parts) query = '/'.join(parts)
else: else:
query = req.env[r'QUERY_STRING'].partition(r'&')[0] query = req.env[r'QUERY_STRING'].partition(r'&')[0]
query = query.partition(r';')[0] query = query.partition(r';')[0]
# Route it to a wire protocol handler if it looks like a wire protocol # Route it to a wire protocol handler if it looks like a wire protocol
# request. # request.
protohandler = wireprotoserver.parsehttprequest(rctx.repo, req, query) protohandler = wireprotoserver.parsehttprequest(rctx, req, query,
self.check_perm)
if protohandler: if protohandler:
try: try:
if query: if query:
raise ErrorResponse(HTTP_NOT_FOUND) raise ErrorResponse(HTTP_NOT_FOUND)
# TODO fold this into parsehttprequest return protohandler['dispatch']()
checkperm = lambda op: self.check_perm(rctx, req, op)
protohandler['proto'].checkperm = checkperm
return protohandler['dispatch'](checkperm)
except ErrorResponse as inst: except ErrorResponse as inst:
return protohandler['handleerror'](inst) return protohandler['handleerror'](inst)
# translate user-visible url structure to internal structure # translate user-visible url structure to internal structure
args = query.split('/', 2) args = query.split('/', 2)
if 'cmd' not in req.form and args and args[0]: if 'cmd' not in req.form and args and args[0]:
cmd = args.pop(0) cmd = args.pop(0)

mercurial/wireproto.py

op, args = pair.split(' ', 1) op, args = pair.split(' ', 1)
vals = {} vals = {}
for a in args.split(','): for a in args.split(','):
if a: if a:
n, v = a.split('=') n, v = a.split('=')
vals[unescapearg(n)] = unescapearg(v) vals[unescapearg(n)] = unescapearg(v)
func, spec = commands[op] func, spec = commands[op]
# If the protocol supports permissions checking, perform that # Validate that client has permissions to perform this command.
# checking on each batched command.
# TODO formalize permission checking as part of protocol interface.
if util.safehasattr(proto, 'checkperm'):
perm = commands[op].permission perm = commands[op].permission
assert perm in ('push', 'pull') assert perm in ('push', 'pull')
proto.checkperm(perm) proto.checkperm(perm)
if spec: if spec:
keys = spec.split() keys = spec.split()
data = {} data = {}
for k in keys: for k in keys:
if k == '*': if k == '*':
star = {} star = {}
for key in vals.keys(): for key in vals.keys():

mercurial/wireprotoserver.py

if v is None: if v is None:
break break
chunks.append(pycompat.bytesurl(v)) chunks.append(pycompat.bytesurl(v))
i += 1 i += 1
return ''.join(chunks) return ''.join(chunks)
class httpv1protocolhandler(wireprototypes.baseprotocolhandler): class httpv1protocolhandler(wireprototypes.baseprotocolhandler):
def __init__(self, req, ui): def __init__(self, req, ui, checkperm):
self._req = req self._req = req
self._ui = ui self._ui = ui
self._checkperm = checkperm
@property @property
def name(self): def name(self):
return 'http-v1' return 'http-v1'
def getargs(self, args): def getargs(self, args):
knownargs = self._args() knownargs = self._args()
data = {} data = {}
compengines = wireproto.supportedcompengines(repo.ui, util.SERVERROLE) compengines = wireproto.supportedcompengines(repo.ui, util.SERVERROLE)
if compengines: if compengines:
comptypes = ','.join(urlreq.quote(e.wireprotosupport().name) comptypes = ','.join(urlreq.quote(e.wireprotosupport().name)
for e in compengines) for e in compengines)
caps.append('compression=%s' % comptypes) caps.append('compression=%s' % comptypes)
return caps return caps
def checkperm(self, perm):
return self._checkperm(perm)
# This method exists mostly so that extensions like remotefilelog can # This method exists mostly so that extensions like remotefilelog can
# disable a kludgey legacy method only over http. As of early 2018, # disable a kludgey legacy method only over http. As of early 2018,
# there are no other known users, so with any luck we can discard this # there are no other known users, so with any luck we can discard this
# hook if remotefilelog becomes a first-party extension. # hook if remotefilelog becomes a first-party extension.
def iscmd(cmd): def iscmd(cmd):
return cmd in wireproto.commands return cmd in wireproto.commands
def parsehttprequest(repo, req, query): def parsehttprequest(rctx, req, query, checkperm):
"""Parse the HTTP request for a wire protocol request. """Parse the HTTP request for a wire protocol request.
If the current request appears to be a wire protocol request, this If the current request appears to be a wire protocol request, this
function returns a dict with details about that request, including function returns a dict with details about that request, including
an ``abstractprotocolserver`` instance suitable for handling the an ``abstractprotocolserver`` instance suitable for handling the
request. Otherwise, ``None`` is returned. request. Otherwise, ``None`` is returned.
``req`` is a ``wsgirequest`` instance. ``req`` is a ``wsgirequest`` instance.
""" """
repo = rctx.repo
# HTTP version 1 wire protocol requests are denoted by a "cmd" query # HTTP version 1 wire protocol requests are denoted by a "cmd" query
# string parameter. If it isn't present, this isn't a wire protocol # string parameter. If it isn't present, this isn't a wire protocol
# request. # request.
if 'cmd' not in req.form: if 'cmd' not in req.form:
return None return None
cmd = req.form['cmd'][0] cmd = req.form['cmd'][0]
# The "cmd" request parameter is used by both the wire protocol and hgweb. # The "cmd" request parameter is used by both the wire protocol and hgweb.
# While not all wire protocol commands are available for all transports, # While not all wire protocol commands are available for all transports,
# if we see a "cmd" value that resembles a known wire protocol command, we # if we see a "cmd" value that resembles a known wire protocol command, we
# route it to a protocol handler. This is better than routing possible # route it to a protocol handler. This is better than routing possible
# wire protocol requests to hgweb because it prevents hgweb from using # wire protocol requests to hgweb because it prevents hgweb from using
# known wire protocol commands and it is less confusing for machine # known wire protocol commands and it is less confusing for machine
# clients. # clients.
if not iscmd(cmd): if not iscmd(cmd):
return None return None
proto = httpv1protocolhandler(req, repo.ui) proto = httpv1protocolhandler(req, repo.ui,
lambda perm: checkperm(rctx, req, perm))
return { return {
'cmd': cmd, 'cmd': cmd,
'proto': proto, 'proto': proto,
'dispatch': lambda checkperm: _callhttp(repo, req, proto, cmd, 'dispatch': lambda: _callhttp(repo, req, proto, cmd),
checkperm),
'handleerror': lambda ex: _handlehttperror(ex, req, cmd), 'handleerror': lambda ex: _handlehttperror(ex, req, cmd),
} }
def _httpresponsetype(ui, req, prefer_uncompressed): def _httpresponsetype(ui, req, prefer_uncompressed):
"""Determine the appropriate response type and compression settings. """Determine the appropriate response type and compression settings.
Returns a tuple of (mediatype, compengine, engineopts). Returns a tuple of (mediatype, compengine, engineopts).
""" """
# legacy protocol. # legacy protocol.
# Don't allow untrusted settings because disabling compression or # Don't allow untrusted settings because disabling compression or
# setting a very high compression level could lead to flooding # setting a very high compression level could lead to flooding
# the server's network or CPU. # the server's network or CPU.
opts = {'level': ui.configint('server', 'zliblevel')} opts = {'level': ui.configint('server', 'zliblevel')}
return HGTYPE, util.compengines['zlib'], opts return HGTYPE, util.compengines['zlib'], opts
def _callhttp(repo, req, proto, cmd, checkperm): def _callhttp(repo, req, proto, cmd):
def genversion2(gen, engine, engineopts): def genversion2(gen, engine, engineopts):
# application/mercurial-0.2 always sends a payload header # application/mercurial-0.2 always sends a payload header
# identifying the compression engine. # identifying the compression engine.
name = engine.wireprotosupport().name name = engine.wireprotosupport().name
assert 0 < len(name) < 256 assert 0 < len(name) < 256
yield struct.pack('B', len(name)) yield struct.pack('B', len(name))
yield name yield name
for chunk in gen: for chunk in gen:
yield chunk yield chunk
if not wireproto.commands.commandavailable(cmd, proto): if not wireproto.commands.commandavailable(cmd, proto):
req.respond(HTTP_OK, HGERRTYPE, req.respond(HTTP_OK, HGERRTYPE,
body=_('requested wire protocol command is not available ' body=_('requested wire protocol command is not available '
'over HTTP')) 'over HTTP'))
return [] return []
checkperm(wireproto.commands[cmd].permission) proto.checkperm(wireproto.commands[cmd].permission)
rsp = wireproto.dispatch(repo, proto, cmd) rsp = wireproto.dispatch(repo, proto, cmd)
if isinstance(rsp, bytes): if isinstance(rsp, bytes):
req.respond(HTTP_OK, HGTYPE, body=rsp) req.respond(HTTP_OK, HGTYPE, body=rsp)
return [] return []
elif isinstance(rsp, wireprototypes.bytesresponse): elif isinstance(rsp, wireprototypes.bytesresponse):
req.respond(HTTP_OK, HGTYPE, body=rsp.data) req.respond(HTTP_OK, HGTYPE, body=rsp.data)
def client(self): def client(self):
client = encoding.environ.get('SSH_CLIENT', '').split(' ', 1)[0] client = encoding.environ.get('SSH_CLIENT', '').split(' ', 1)[0]
return 'remote:ssh:' + client return 'remote:ssh:' + client
def addcapabilities(self, repo, caps): def addcapabilities(self, repo, caps):
return caps return caps
def checkperm(self, perm):
pass
class sshv2protocolhandler(sshv1protocolhandler): class sshv2protocolhandler(sshv1protocolhandler):
"""Protocol handler for version 2 of the SSH protocol.""" """Protocol handler for version 2 of the SSH protocol."""
@property @property
def name(self): def name(self):
return wireprototypes.SSHV2 return wireprototypes.SSHV2
def _runsshserver(ui, repo, fin, fout, ev): def _runsshserver(ui, repo, fin, fout, ev):

mercurial/wireprototypes.py

@abc.abstractmethod @abc.abstractmethod
def addcapabilities(self, repo, caps): def addcapabilities(self, repo, caps):
"""Adds advertised capabilities specific to this protocol. """Adds advertised capabilities specific to this protocol.
Receives the list of capabilities collected so far. Receives the list of capabilities collected so far.
Returns a list of capabilities. The passed in argument can be returned. Returns a list of capabilities. The passed in argument can be returned.
""" """
@abc.abstractmethod
def checkperm(self, perm):
"""Validate that the client has permissions to perform a request.
The argument is the permission required to proceed. If the client
doesn't have that permission, the exception should raise or abort
in a protocol specific manner.
"""

tests/test-wireproto.py

def __init__(self, args): def __init__(self, args):
self.args = args self.args = args
def getargs(self, spec): def getargs(self, spec):
args = self.args args = self.args
args.setdefault(b'*', {}) args.setdefault(b'*', {})
names = spec.split() names = spec.split()
return [args[n] for n in names] return [args[n] for n in names]
def checkperm(self, perm):
pass
class clientpeer(wireproto.wirepeer): class clientpeer(wireproto.wirepeer):
def __init__(self, serverrepo): def __init__(self, serverrepo):
self.serverrepo = serverrepo self.serverrepo = serverrepo
@property @property
def ui(self): def ui(self):
return self.serverrepo.ui return self.serverrepo.ui