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netinet6: allow ND entries creation for all directly-reachable

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destinations.

The current assumption is that kernel-handled rtadv prefixes along with
 the interface address prefixes are the only prefixes considered in
 the ND neighbor eligibility code.
Change this by allowing any non-gatewaye routes to be eligible. This
 will allow DHCPv6-controlled routes to be correctly handled by
 the ND code.
Refactor nd6_is_new_addr_neighbor() to enable more deterministic
 performance in "found" case and remove non-needed
 V_rt_add_addr_allfibs handling logic.

Reviewed By: kbowling
Differential Revision: https://reviews.freebsd.org/D23695
MFC after:	1 month
This commit is contained in:
Alexander V. Chernikov 2022-08-10 11:51:58 +00:00
parent 8d6b3a8570
commit f998535a66
1 changed files with 22 additions and 68 deletions
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90
sys/netinet6/nd6.c
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@ -71,6 +71,7 @@ __FBSDID("$FreeBSD$");
#include <netinet/in_kdtrace.h>
#include <net/if_llatbl.h>
#include <netinet/if_ether.h>
#include <netinet6/in6_fib.h>
#include <netinet6/in6_var.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
@ -129,7 +130,7 @@ VNET_DEFINE(int, nd6_recalc_reachtm_interval) = ND6_RECALC_REACHTM_INTERVAL;
int (*send_sendso_input_hook)(struct mbuf *, struct ifnet *, int, int);
static int nd6_is_new_addr_neighbor(const struct sockaddr_in6 *,
static bool nd6_is_new_addr_neighbor(const struct sockaddr_in6 *,
struct ifnet *);
static void nd6_setmtu0(struct ifnet *, struct nd_ifinfo *);
static void nd6_slowtimo(void *);
@ -1225,20 +1226,11 @@ nd6_alloc(const struct in6_addr *addr6, int flags, struct ifnet *ifp)
}
/*
* Test whether a given IPv6 address is a neighbor or not, ignoring
* the actual neighbor cache. The neighbor cache is ignored in order
* to not reenter the routing code from within itself.
* Test whether a given IPv6 address can be a neighbor.
*/
static int
static bool
nd6_is_new_addr_neighbor(const struct sockaddr_in6 *addr, struct ifnet *ifp)
{
struct nd_prefix *pr;
struct ifaddr *ifa;
struct rt_addrinfo info;
struct sockaddr_in6 rt_key;
const struct sockaddr *dst6;
uint64_t genid;
int error, fibnum;
/*
* A link-local address is always a neighbor.
@ -1262,89 +1254,51 @@ nd6_is_new_addr_neighbor(const struct sockaddr_in6 *addr, struct ifnet *ifp)
else
return (0);
}
/* Checking global unicast */
bzero(&rt_key, sizeof(rt_key));
bzero(&info, sizeof(info));
info.rti_info[RTAX_DST] = (struct sockaddr *)&rt_key;
/* If an address is directly reachable, it is a neigbor */
struct nhop_object *nh;
nh = fib6_lookup(ifp->if_fib, &addr->sin6_addr, 0, NHR_NONE, 0);
if (nh != NULL && nh->nh_aifp == ifp && (nh->nh_flags & NHF_GATEWAY) == 0)
return (true);
/*
* If the address matches one of our addresses,
* it should be a neighbor.
* If the address matches one of our on-link prefixes, it should be a
* neighbor.
* Check prefixes with desired on-link state, as some may be not
* installed in the routing table.
*/
bool matched = false;
struct nd_prefix *pr;
ND6_RLOCK();
restart:
LIST_FOREACH(pr, &V_nd_prefix, ndpr_entry) {
if (pr->ndpr_ifp != ifp)
continue;
if ((pr->ndpr_stateflags & NDPRF_ONLINK) == 0) {
dst6 = (const struct sockaddr *)&pr->ndpr_prefix;
/*
* We only need to check all FIBs if add_addr_allfibs
* is unset. If set, checking any FIB will suffice.
*/
fibnum = V_rt_add_addr_allfibs ? rt_numfibs - 1 : 0;
for (; fibnum < rt_numfibs; fibnum++) {
genid = V_nd6_list_genid;
ND6_RUNLOCK();
/*
* Restore length field before
* retrying lookup
*/
rt_key.sin6_len = sizeof(rt_key);
error = rib_lookup_info(fibnum, dst6, 0, 0,
&info);
ND6_RLOCK();
if (genid != V_nd6_list_genid)
goto restart;
if (error == 0)
break;
}
if (error != 0)
continue;
/*
* This is the case where multiple interfaces
* have the same prefix, but only one is installed
* into the routing table and that prefix entry
* is not the one being examined here.
*/
if (!IN6_ARE_ADDR_EQUAL(&pr->ndpr_prefix.sin6_addr,
&rt_key.sin6_addr))
continue;
}
if ((pr->ndpr_stateflags & NDPRF_ONLINK) == 0)
continue;
if (IN6_ARE_MASKED_ADDR_EQUAL(&pr->ndpr_prefix.sin6_addr,
&addr->sin6_addr, &pr->ndpr_mask)) {
ND6_RUNLOCK();
return (1);
matched = true;
break;
}
}
ND6_RUNLOCK();
if (matched)
return (true);
/*
* If the address is assigned on the node of the other side of
* a p2p interface, the address should be a neighbor.
*/
if (ifp->if_flags & IFF_POINTOPOINT) {
struct epoch_tracker et;
struct ifaddr *ifa;
NET_EPOCH_ENTER(et);
CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
if (ifa->ifa_addr->sa_family != addr->sin6_family)
continue;
if (ifa->ifa_dstaddr != NULL &&
sa_equal(addr, ifa->ifa_dstaddr)) {
NET_EPOCH_EXIT(et);
return 1;
return (true);
}
}
NET_EPOCH_EXIT(et);
}
/*