On 12/01, Jeff King wrote:
> On Thu, Dec 01, 2016 at 10:14:15AM -0800, Brandon Williams wrote:
>
> > > 1. The new policy config lets you say "only allow this protocol when
> > > the user specifies it". But when http.c calls is_transport_allowed(),
> > > the latter has no idea that we are asking it about potential
> > > redirects (which obviously do _not_ come from the user), and would
> > > erroneously allow them.
> > >
> > > I think this needs fixed before the topic is merged. It's not a
> > > regression, as it only comes into play if you use the new policy
> > > config. But it is a minor security hole in the new feature.
> >
> > I agree and it should be an easy fix. We can just add a parameter like
> > so:
> >
> > diff --git a/transport.c b/transport.c
> > index 2c0ec76..d38d50f 100644
> > --- a/transport.c
> > +++ b/transport.c
> > @@ -723,7 +723,7 @@ static enum protocol_allow_config get_protocol_config(const char *type)
> > return PROTOCOL_ALLOW_USER_ONLY;
> > }
> >
> > -int is_transport_allowed(const char *type)
> > +int is_transport_allowed(const char *type, int redirect)
> > {
> > const struct string_list *whitelist = protocol_whitelist();
> > if (whitelist)
> > @@ -735,7 +735,7 @@ int is_transport_allowed(const char *type)
> > case PROTOCOL_ALLOW_NEVER:
> > return 0;
> > case PROTOCOL_ALLOW_USER_ONLY:
> > - return git_env_bool("GIT_PROTOCOL_FROM_USER", 1);
> > + return git_env_bool("GIT_PROTOCOL_FROM_USER", !redirect);
> > }
> >
> > die("BUG: invalid protocol_allow_config type");
> >
> > That way the libcurl code can say it is asking if it is ok to redirect
> > to that protocol.
>
> I wouldn't expect anyone to ever set GIT_PROTOCOL_FROM_USER=1, but it
> does behave in a funny way here, overriding the "redirect" flag. I think
> we'd want something more like:
>
> if (redirect < 0)
> redirect = git_env_bool("GIT_PROTOCOL_FROM_USER", 1);
>
> and then pass in "-1" from transport_check_allowed().
I don't think I quite follow your solution but I came up with this:
case PROTOCOL_ALLOW_USER_ONLY:
return redirect ? 0 : git_env_bool("GIT_PROTOCOL_FROM_USER", 1);
Which should address the same issue.
--
Brandon Williams