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Fix arp/ndp deletion broken by 2fe5a79425.

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Changes in the 2fe5a79425 moved dst sockaddr masking from the
 routing control plane to the rtsock code.

It broke arp/ndp deletion.
It turns out, arp/ndp perform RTM_GET request first to get an
 interface index necessary for the deletion.
Then they simply stamp the reply with RTF_LLDATA and set the
 command to RTM_DELETE.
As a result, kernel receives request with non-empty RTA_NETMASK
 and clears RTA_DST host bits before passing the message to the
 lla code.

De facto, the only needed bits are RTA_DST, RTA_GATEWAY and the
 subset of rtm_flags.

With that in mind, fix the interace by clearing RTA_NETMASK
 for every messages with RTF_LLDATA.

While here, cleanup arp/ndp code a bit.

MFC after:	1 day
Reviewed by:	gnn
Differential Revision:	https://reviews.freebsd.org/D28804
This commit is contained in:
Alexander V. Chernikov 2021-02-19 21:09:17 +00:00
parent a78bb831a1
commit f9e1cd6c99
3 changed files with 21 additions and 29 deletions
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31
sys/net/rtsock.c
View file

@ -1376,6 +1376,14 @@ cleanup_xaddrs_gateway(struct rt_addrinfo *info)
return (0);
}
static void
remove_netmask(struct rt_addrinfo *info)
{
info->rti_info[RTAX_NETMASK] = NULL;
info->rti_flags |= RTF_HOST;
info->rti_addrs &= ~RTA_NETMASK;
}
#ifdef INET
static int
cleanup_xaddrs_inet(struct rt_addrinfo *info)
@ -1405,11 +1413,8 @@ cleanup_xaddrs_inet(struct rt_addrinfo *info)
if (mask.s_addr != INADDR_BROADCAST)
fill_sockaddr_inet(mask_sa, mask);
else {
info->rti_info[RTAX_NETMASK] = NULL;
info->rti_flags |= RTF_HOST;
info->rti_addrs &= ~RTA_NETMASK;
}
else
remove_netmask(info);
/* Check gateway */
if (info->rti_info[RTAX_GATEWAY] != NULL)
@ -1445,11 +1450,8 @@ cleanup_xaddrs_inet6(struct rt_addrinfo *info)
if (!IN6_ARE_ADDR_EQUAL(&mask, &in6mask128))
fill_sockaddr_inet6(mask_sa, &mask, 0);
else {
info->rti_info[RTAX_NETMASK] = NULL;
info->rti_flags |= RTF_HOST;
info->rti_addrs &= ~RTA_NETMASK;
}
else
remove_netmask(info);
/* Check gateway */
if (info->rti_info[RTAX_GATEWAY] != NULL)
@ -1467,6 +1469,15 @@ cleanup_xaddrs(struct rt_addrinfo *info)
if (info->rti_info[RTAX_DST] == NULL)
return (EINVAL);
if (info->rti_flags & RTF_LLDATA) {
/*
* arp(8)/ndp(8) sends RTA_NETMASK for the associated
* prefix along with the actual address in RTA_DST.
* Remove netmask to avoid unnecessary address masking.
*/
remove_netmask(info);
}
switch (info->rti_info[RTAX_DST]->sa_family) {
#ifdef INET
case AF_INET:

9
usr.sbin/arp/arp.c
View file

@ -717,7 +717,6 @@ rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl)
static int seq;
int rlen;
int l;
struct sockaddr_in so_mask, *som = &so_mask;
static int s = -1;
static pid_t pid;
@ -735,9 +734,6 @@ rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl)
xo_err(1, "socket");
pid = getpid();
}
bzero(&so_mask, sizeof(so_mask));
so_mask.sin_len = 8;
so_mask.sin_addr.s_addr = 0xffffffff;
errno = 0;
/*
@ -758,10 +754,6 @@ rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl)
rtm->rtm_rmx.rmx_expire = expire_time;
rtm->rtm_inits = RTV_EXPIRE;
rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
if (doing_proxy) {
rtm->rtm_addrs |= RTA_NETMASK;
rtm->rtm_flags &= ~RTF_HOST;
}
/* FALLTHROUGH */
case RTM_GET:
rtm->rtm_addrs |= RTA_DST;
@ -776,7 +768,6 @@ rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl)
NEXTADDR(RTA_DST, dst);
NEXTADDR(RTA_GATEWAY, sdl);
NEXTADDR(RTA_NETMASK, som);
rtm->rtm_msglen = cp - (char *)&m_rtmsg;
doit:

10
usr.sbin/ndp/ndp.c
View file

@ -860,12 +860,6 @@ rtmsg(int cmd)
rtm->rtm_inits = RTV_EXPIRE;
}
rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
#if 0 /* we don't support ipv6addr/128 type proxying */
if (rtm->rtm_flags & RTF_ANNOUNCE) {
rtm->rtm_flags &= ~RTF_HOST;
rtm->rtm_addrs |= RTA_NETMASK;
}
#endif
/* FALLTHROUGH */
case RTM_GET:
rtm->rtm_addrs |= RTA_DST;
@ -873,10 +867,6 @@ rtmsg(int cmd)
NEXTADDR(RTA_DST, sin_m);
NEXTADDR(RTA_GATEWAY, sdl_m);
#if 0 /* we don't support ipv6addr/128 type proxying */
memset(&so_mask.sin6_addr, 0xff, sizeof(so_mask.sin6_addr));
NEXTADDR(RTA_NETMASK, so_mask);
#endif
rtm->rtm_msglen = cp - (char *)&m_rtmsg;
doit: