git: 145bf6c0af48 - main - Fix blackhole/reject routes.

Mateusz Guzik mjguzik at gmail.com
Fri Feb 12 01:59:08 UTC 2021


This breaks building a kernel with INET6 for me, I presume it will
also break LINT-NOINET

On 2/12/21, Alexander V. Chernikov <melifaro at freebsd.org> wrote:
> The branch main has been updated by melifaro:
>
> URL:
> https://cgit.FreeBSD.org/src/commit/?id=145bf6c0af48b89f13465e145f4516de37c31d85
>
> commit 145bf6c0af48b89f13465e145f4516de37c31d85
> Author:     Alexander V. Chernikov <melifaro at FreeBSD.org>
> AuthorDate: 2021-02-08 23:29:05 +0000
> Commit:     Alexander V. Chernikov <melifaro at FreeBSD.org>
> CommitDate: 2021-02-11 23:08:55 +0000
>
>     Fix blackhole/reject routes.
>
>     Traditionally *BSD routing stack required to supply some
>      interface data for blackhole/reject routes. This lead to
>      varieties of hacks in routing daemons when inserting such routes.
>     With the recent routeing stack changes, gateway sockaddr without
>      RTF_GATEWAY started to be treated differently, purely as link
>      identifier.
>
>     This change broke net/bird, which installs blackhole routes with
>      127.0.0.1 gateway without RTF_GATEWAY flags.
>
>     Fix this by automatically constructing necessary gateway data at
>      rtsock level if RTF_REJECT/RTF_BLACKHOLE is set.
>
>     Reported by:    Marek Zarychta <zarychtam at plan-b.pwste.edu.pl>
>     Reviewed by:    donner
>     MFC after:      1 week
> ---
>  sys/net/rtsock.c | 58
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 56 insertions(+), 2 deletions(-)
>
> diff --git a/sys/net/rtsock.c b/sys/net/rtsock.c
> index ba1182d55439..f67252f9fd5f 100644
> --- a/sys/net/rtsock.c
> +++ b/sys/net/rtsock.c
> @@ -562,6 +562,50 @@ rtm_get_jailed(struct rt_addrinfo *info, struct ifnet
> *ifp,
>  	return (0);
>  }
>
> +static int
> +fill_blackholeinfo(struct rt_addrinfo *info, union sockaddr_union *saun)
> +{
> +	struct ifaddr *ifa;
> +	sa_family_t saf;
> +
> +	if (V_loif == NULL) {
> +		printf("Unable to add blackhole/reject nhop without loopback");
> +		return (ENOTSUP);
> +	}
> +	info->rti_ifp = V_loif;
> +
> +	saf = info->rti_info[RTAX_DST]->sa_family;
> +
> +	CK_STAILQ_FOREACH(ifa, &info->rti_ifp->if_addrhead, ifa_link) {
> +		if (ifa->ifa_addr->sa_family == saf) {
> +			info->rti_ifa = ifa;
> +			break;
> +		}
> +	}
> +	if (info->rti_ifa == NULL)
> +		return (ENOTSUP);
> +
> +	bzero(saun, sizeof(union sockaddr_union));
> +	switch (saf) {
> +	case AF_INET:
> +		saun->sin.sin_family = AF_INET;
> +		saun->sin.sin_len = sizeof(struct sockaddr_in);
> +		saun->sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
> +		break;
> +	case AF_INET6:
> +		saun->sin6.sin6_family = AF_INET6;
> +		saun->sin6.sin6_len = sizeof(struct sockaddr_in6);
> +		saun->sin6.sin6_addr = in6addr_loopback;
> +		break;
> +	default:
> +		return (ENOTSUP);
> +	}
> +	info->rti_info[RTAX_GATEWAY] = &saun->sa;
> +	info->rti_flags |= RTF_GATEWAY;
> +
> +	return (0);
> +}
> +
>  /*
>   * Fills in @info based on userland-provided @rtm message.
>   *
> @@ -944,7 +988,6 @@ route_output(struct mbuf *m, struct socket *so, ...)
>  #endif
>  	int alloc_len = 0, len, error = 0, fibnum;
>  	sa_family_t saf = AF_UNSPEC;
> -	struct walkarg w;
>  	struct rib_cmd_info rc;
>  	struct nhop_object *nh;
>
> @@ -972,7 +1015,6 @@ route_output(struct mbuf *m, struct socket *so, ...)
>
>  	m_copydata(m, 0, len, (caddr_t)rtm);
>  	bzero(&info, sizeof(info));
> -	bzero(&w, sizeof(w));
>  	nh = NULL;
>
>  	if (rtm->rtm_version != RTM_VERSION) {
> @@ -1004,6 +1046,18 @@ route_output(struct mbuf *m, struct socket *so, ...)
>  		goto flush;
>  	}
>
> +	union sockaddr_union gw_saun;
> +	int blackhole_flags = rtm->rtm_flags & (RTF_BLACKHOLE|RTF_REJECT);
> +	if (blackhole_flags != 0) {
> +		if (blackhole_flags != (RTF_BLACKHOLE | RTF_REJECT))
> +			error = fill_blackholeinfo(&info, &gw_saun);
> +		else
> +			error = EINVAL;
> +		if (error != 0)
> +			senderr(error);
> +		/* TODO: rebuild rtm from scratch */
> +	}
> +
>  	switch (rtm->rtm_type) {
>  	case RTM_ADD:
>  	case RTM_CHANGE:
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-- 
Mateusz Guzik <mjguzik gmail.com>


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