From: Denis Fondras <denis@openbsd.org>
Subject: Re: in6_update_ifa: destination addressses and loopback interfaces
To: tech@openbsd.org
Date: Tue, 16 Apr 2024 15:41:57 +0200

Le Tue, Apr 16, 2024 at 03:08:35PM +0200, Florian Obser a écrit :
> Destination addresses make no sense on loopback interfaces.
> 
> While here use (variable & FLAG) or !(variable & FLAG) consistently in
> in6_update_ifa().
> 
> I suspect this will make upcoming work slightly easier.
> 
> OK?
> 

OK denis@

> diff --git in6.c in6.c
> index 1266354e202..6e185efb2ad 100644
> --- in6.c
> +++ in6.c
> @@ -565,7 +565,7 @@ in6_update_ifa(struct ifnet *ifp, struct in6_aliasreq *ifra,
>  	 * The destination address for a p2p link must have a family
>  	 * of AF_UNSPEC or AF_INET6.
>  	 */
> -	if ((ifp->if_flags & IFF_POINTOPOINT) != 0 &&
> +	if ((ifp->if_flags & IFF_POINTOPOINT) &&
>  	    ifra->ifra_dstaddr.sin6_family != AF_INET6 &&
>  	    ifra->ifra_dstaddr.sin6_family != AF_UNSPEC)
>  		return (EAFNOSUPPORT);
> @@ -603,19 +603,18 @@ in6_update_ifa(struct ifnet *ifp, struct in6_aliasreq *ifra,
>  	 * zone identifier.
>  	 */
>  	dst6 = ifra->ifra_dstaddr;
> -	if ((ifp->if_flags & (IFF_POINTOPOINT|IFF_LOOPBACK)) != 0 &&
> +	if ((ifp->if_flags & IFF_POINTOPOINT) &&
>  	    (dst6.sin6_family == AF_INET6)) {
>  		error = in6_check_embed_scope(&dst6, ifp->if_index);
>  		if (error)
>  			return error;
>  	}
>  	/*
> -	 * The destination address can be specified only for a p2p or a
> -	 * loopback interface.  If specified, the corresponding prefix length
> -	 * must be 128.
> +	 * The destination address can be specified only for a p2p interface.
> +	 * If specified, the corresponding prefix length must be 128.
>  	 */
>  	if (ifra->ifra_dstaddr.sin6_family == AF_INET6) {
> -		if ((ifp->if_flags & (IFF_POINTOPOINT|IFF_LOOPBACK)) == 0)
> +		if (!(ifp->if_flags & IFF_POINTOPOINT))
>  			return (EINVAL);
>  		if (plen != 128)
>  			return (EINVAL);
> @@ -652,7 +651,7 @@ in6_update_ifa(struct ifnet *ifp, struct in6_aliasreq *ifra,
>  		ia6->ia_addr.sin6_family = AF_INET6;
>  		ia6->ia_addr.sin6_len = sizeof(ia6->ia_addr);
>  		ia6->ia6_updatetime = getuptime();
> -		if ((ifp->if_flags & (IFF_POINTOPOINT | IFF_LOOPBACK)) != 0) {
> +		if (ifp->if_flags & IFF_POINTOPOINT) {
>  			/*
>  			 * XXX: some functions expect that ifa_dstaddr is not
>  			 * NULL for p2p interfaces.
> @@ -687,7 +686,7 @@ in6_update_ifa(struct ifnet *ifp, struct in6_aliasreq *ifra,
>  	/*
>  	 * If a new destination address is specified, scrub the old one and
>  	 * install the new destination.  Note that the interface must be
> -	 * p2p or loopback (see the check above.)
> +	 * p2p (see the check above.)
>  	 */
>  	if ((ifp->if_flags & IFF_POINTOPOINT) && dst6.sin6_family == AF_INET6 &&
>  	    !IN6_ARE_ADDR_EQUAL(&dst6.sin6_addr, &ia6->ia_dstaddr.sin6_addr)) {
> 
> -- 
> In my defence, I have been left unsupervised.
>