Re: [Openvpn-devel] [PATCH ovpn net 3/5] ovpn: reject multipeer peers without VPN addresses

On Fri, 14 Aug 2026 12:00:25 +0200, Sabrina Dubroca <[email protected]> wrote:
> 2026-07-29, 17:37:41 +0200, Ralf Lici wrote:
> > In MP mode, ovpn uses the peer VPN addresses to select the peer for
> > outgoing tunnel packets. Peer creation currently requires a VPN IPv4 or
> > IPv6 attribute, but it only checks for the presence of the attribute and
> > not for a usable address value.
> > 
> > This allows userspace to create an MP peer with only unspecified VPN
> > addresses, or to update an existing peer so that both VPN address
> > families become unspecified. Such a peer cannot be selected through the
> > VPN address hash tables.
> > 
> > Reject MP peer creation or update when the resulting peer would not have
> > at least one VPN address configured.
>
> Same comment about "this has never worked".
>

ACK.

> > @@ -371,11 +373,19 @@ int ovpn_nl_peer_new_doit(struct sk_buff *skb, struct genl_info *info)
> >  		return -EINVAL;
> >  
> >  	/* in MP mode VPN IPs are required for selecting the right peer */
> > -	if (ovpn->mode == OVPN_MODE_MP && !attrs[OVPN_A_PEER_VPN_IPV4] &&
> > -	    !attrs[OVPN_A_PEER_VPN_IPV6]) {
> > -		NL_SET_ERR_MSG_FMT_MOD(info->extack,
> > -				       "VPN IP must be provided in MP mode");
> > -		return -EINVAL;
> > +	if (ovpn->mode == OVPN_MODE_MP) {
> > +		if (attrs[OVPN_A_PEER_VPN_IPV4])
> > +			vpn_addr4.s_addr =
> > +				nla_get_in_addr(attrs[OVPN_A_PEER_VPN_IPV4]);
> > +		if (attrs[OVPN_A_PEER_VPN_IPV6])
> > +			vpn_addr6 =
> > +				nla_get_in6_addr(attrs[OVPN_A_PEER_VPN_IPV6]);
> > +
> > +		if (!vpn_addr4.s_addr && ipv6_addr_any(&vpn_addr6)) {
>
> minor nit, only if you end up resending this patch: the inconsistency
> between !s_addr and != htonl(INADDR_ANY) isn't great. (but I don't
> think it's confusing anyone)
>

Ah right, I missed this one. I'll resend the series anyway so I'll make
sure to use != htonl(INADDR_ANY) here as well.

-- 
Ralf Lici
Mandelbit Srl


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