Re: What to use in place of abstract unix sockets?

On Fri, Dec 10, 2021 at 12:54 AM Gleb Popov <arrowd@freebsd.org> wrote:
>
> On Wed, Dec 8, 2021 at 10:50 AM Eugene Grosbein <eugen@grosbein.net> wrote:
>
> > 08.12.2021 13:43, Gleb Popov wrote:
> >
> > > Hello hackers.
> > >
> > > I'm porting a software that does the following things on Linux:
> > >
> > > 1. Binds an abstract UDS (the socket name starts with '\0')
> > > 2. Launches a "client" process.
> > > 3. "Client" uses chroot() to constrain itself in a sort of jail.
> > > 4. "Client" connects to the abstract UDS.
> > >
> > >>From what I can tell, this works because abstract UDS's do not use the
> > > filesystem namespace, which is why "client" can connect out of the
> > > chroot'ed environment.
> > >
> > > What can I do to make this software work for FreeBSD? Simply using
> > regular
> > > UDS instead of abstract ones doesn't work for obvious reasons - the
> > > "client" can't find the socket file.
> > >
> > > Thanks in advance.
> >
> > If they are parent/child, you could try using socketpair().
> >
>
> There are actually multiple children. If I understand it right, using
> socketpair() would lead to N sockets on the server side for the N connected
> clients. Right now there is a single UDS that handles all connections, so
> rewriting it with socketpair() would be problematic, I think.
>
>
>
>
> On Thu, Dec 9, 2021 at 3:08 AM Daniel O'Connor <darius@dons.net.au> wrote:
>
> >
> >
> > > On 8 Dec 2021, at 17:13, Gleb Popov <arrowd@freebsd.org> wrote:
> > > I'm porting a software that does the following things on Linux:
> > >
> > > 1. Binds an abstract UDS (the socket name starts with '\0')
> > > 2. Launches a "client" process.
> > > 3. "Client" uses chroot() to constrain itself in a sort of jail.
> > > 4. "Client" connects to the abstract UDS.
> > >
> > > From what I can tell, this works because abstract UDS's do not use the
> > > filesystem namespace, which is why "client" can connect out of the
> > > chroot'ed environment.
> > >
> > > What can I do to make this software work for FreeBSD? Simply using
> > regular
> > > UDS instead of abstract ones doesn't work for obvious reasons - the
> > > "client" can't find the socket file.
> >
> > If the parent knows where the child will chroot it could create a unix
> > domain socket under that directory somewhere.
> >
>
> Same problem as above - there should be a single socket on the server side.

Since socketpair() doesn't work in this case, why not just use a UDP
socket bound to 127.0.0.1 ?