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

[Mateusz Guzik]

I mean *without* INET6

On 2/12/21, Mateusz Guzik <mjguzik at gmail.com> wrote:
> 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>
>


-- 
Mateusz Guzik <mjguzik gmail.com>