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Fix blackhole/reject routes.

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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
This commit is contained in:
Alexander V. Chernikov 2021-02-08 23:29:05 +00:00
parent e6405c8c37
commit 145bf6c0af
1 changed files with 56 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
sys/net/rtsock.c
View File

@ -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: