comparison mercurial/dispatch.py @ 32050:77eaf9539499 stable 4.1.3

dispatch: protect against malicious 'hg serve --stdio' invocations (sec)

Some shared-ssh installations assume that 'hg serve --stdio' is a safe
command to run for minimally trusted users. Unfortunately, the messy
implementation of argument parsing here meant that trying to access a
repo named '--debugger' would give the user a pdb prompt, thereby
sidestepping any hoped-for sandboxing. Serving repositories over HTTP(S)
is unaffected.

We're not currently hardening any subcommands other than 'serve'. If
your service exposes other commands to users with arbitrary repository
names, it is imperative that you defend against repository names of
'--debugger' and anything starting with '--config'.

The read-only mode of hg-ssh stopped working because it provided its hook
configuration to "hg serve --stdio" via --config parameter. This is banned for
security reasons now. This patch switches it to directly call ui.setconfig().
If your custom hosting infrastructure relies on passing --config to
"hg serve --stdio", you'll need to find a different way to get that configuration
into Mercurial, either by using ui.setconfig() as hg-ssh does in this patch,
or by placing an hgrc file someplace where Mercurial will read it.

[e-mail] provided some extra fixes for the dispatch code and
for hg-ssh in places that I overlooked.

31760:68f263f52d2e

                signal.signal(num, catchterm)
    except ValueError:
        pass # happens if called in a thread

    def _runcatchfunc():
        try:
            debugger = 'pdb'
            debugtrace = {
                'pdb' : pdb.set_trace
            }

32050:77eaf9539499

                signal.signal(num, catchterm)
    except ValueError:
        pass # happens if called in a thread

    def _runcatchfunc():
        realcmd = None
        try:
            cmdargs = fancyopts.fancyopts(req.args[:], commands.globalopts, {})
            cmd = cmdargs[0]
            aliases, entry = cmdutil.findcmd(cmd, commands.table, False)
            realcmd = aliases[0]
        except (error.UnknownCommand, error.AmbiguousCommand,
                IndexError, getopt.GetoptError):
            # Don't handle this here. We know the command is
            # invalid, but all we're worried about for now is that
            # it's not a command that server operators expect to
            # be safe to offer to users in a sandbox.
            pass
        if realcmd == 'serve' and '--stdio' in cmdargs:
            # We want to constrain 'hg serve --stdio' instances pretty
            # closely, as many shared-ssh access tools want to grant
            # access to run *only* 'hg -R $repo serve --stdio'. We
            # restrict to exactly that set of arguments, and prohibit
            # any repo name that starts with '--' to prevent
            # shenanigans wherein a user does something like pass
            # --debugger or --config=ui.debugger=1 as a repo
            # name. This used to actually run the debugger.
            if (len(req.args) != 4 or
                req.args[0] != '-R' or
                req.args[1].startswith('--') or
                req.args[2] != 'serve' or
                req.args[3] != '--stdio'):
                raise error.Abort(
                    _('potentially unsafe serve --stdio invocation: %r') %
                    (req.args,))

        try:
            debugger = 'pdb'
            debugtrace = {
                'pdb' : pdb.set_trace
            }