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author | melifaro <melifaro@FreeBSD.org> | 2015-09-16 14:26:28 +0000 |
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committer | melifaro <melifaro@FreeBSD.org> | 2015-09-16 14:26:28 +0000 |
commit | 493325342d2aeb9d06e09827e294b9407ec60e9b (patch) | |
tree | e04e3fcd4841d6aa1ce593fcc38aa9bb51b4cd33 /sys/netinet6/nd6.c | |
parent | 1391356f66bee9ea2da2af8675144717f9efcfb3 (diff) | |
download | FreeBSD-src-493325342d2aeb9d06e09827e294b9407ec60e9b.zip FreeBSD-src-493325342d2aeb9d06e09827e294b9407ec60e9b.tar.gz |
Simplify the way of attaching IPv6 link-layer header.
Problem description:
How do we currently perform layer 2 resolution and header imposition:
For IPv4 we have the following chain:
ip_output() -> (ether|atm|whatever)_output() -> arpresolve()
Lookup is done in proper place (link-layer output routine) and it is possible
to provide cached lle data.
For IPv6 situation is more complex:
ip6_output() -> nd6_output() -> nd6_output_ifp() -> (whatever)_output() ->
nd6_storelladdr()
We have ip6_ouput() which calls nd6_output() instead of link output routine.
nd6_output() does the following:
* checks if lle exists, creates it if needed (similar to arpresolve())
* performes lle state transitions (similar to arpresolve())
* calls nd6_output_ifp() which pushes packets to link output routine along
with running SeND/MAC hooks regardless of lle state
(e.g. works as run-hooks placeholder).
After that, iface output routine like ether_output() calls nd6_storelladdr()
which performs lle lookup once again.
As a result, we perform lookup twice for each outgoing packet for most types
of interfaces. We also need to maintain runtime-checked table of 'nd6-free'
interfaces (see nd6_need_cache()).
Fix this behavior by eliminating first ND lookup. To be more specific:
* make all nd6_output() consumers use nd6_output_ifp() instead
* rename nd6_output[_slow]() to nd6_resolve_[slow]()
* convert nd6_resolve() and nd6_resolve_slow() to arpresolve() semantics,
e.g. copy L2 address to buffer instead of pushing packet towards lower
layers
* Make all nd6_storelladdr() users use nd6_resolve()
* eliminate nd6_storelladdr()
The resulting callchain is the following:
ip6_output() -> nd6_output_ifp() -> (whatever)_output() -> nd6_resolve()
Error handling:
Currently sending packet to non-existing la results in ip6_<output|forward>
-> nd6_output() -> nd6_output _lle() which returns 0.
In new scenario packet is propagated to <ether|whatever>_output() ->
nd6_resolve() which will return EWOULDBLOCK, and that result
will be converted to 0.
(And EWOULDBLOCK is actually used by IB/TOE code).
Sponsored by: Yandex LLC
Differential Revision: https://reviews.freebsd.org/D1469
Diffstat (limited to 'sys/netinet6/nd6.c')
-rw-r--r-- | sys/netinet6/nd6.c | 192 |
1 files changed, 70 insertions, 122 deletions
diff --git a/sys/netinet6/nd6.c b/sys/netinet6/nd6.c index 2e4c964..5d4d594 100644 --- a/sys/netinet6/nd6.c +++ b/sys/netinet6/nd6.c @@ -136,10 +136,10 @@ static void nd6_free_redirect(const struct llentry *); static void nd6_llinfo_timer(void *); static void clear_llinfo_pqueue(struct llentry *); static void nd6_rtrequest(int, struct rtentry *, struct rt_addrinfo *); -static int nd6_output_lle(struct ifnet *, struct ifnet *, struct mbuf *, - struct sockaddr_in6 *); -static int nd6_output_ifp(struct ifnet *, struct ifnet *, struct mbuf *, - struct sockaddr_in6 *); +static int nd6_resolve_slow(struct ifnet *, struct mbuf *, + const struct sockaddr_in6 *, u_char *, uint32_t *); +static int nd6_need_cache(struct ifnet *); + static VNET_DEFINE(struct callout, nd6_slowtimo_ch); #define V_nd6_slowtimo_ch VNET(nd6_slowtimo_ch) @@ -1904,7 +1904,7 @@ nd6_grab_holdchain(struct llentry *ln, struct mbuf **chain, } } -static int +int nd6_output_ifp(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m, struct sockaddr_in6 *dst) { @@ -1950,16 +1950,29 @@ nd6_output_ifp(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m, } /* - * IPv6 packet output - light version. - * Checks if destination LLE exists and is in proper state - * (e.g no modification required). If not true, fall back to - * "heavy" version. + * Do L2 address resolution for @sa_dst address. Stores found + * address in @desten buffer. Copy of lle ln_flags can be also + * saved in @pflags if @pflags is non-NULL. + * + * If destination LLE does not exists or lle state modification + * is required, call "slow" version. + * + * Return values: + * - 0 on success (address copied to buffer). + * - EWOULDBLOCK (no local error, but address is still unresolved) + * - other errors (alloc failure, etc) */ int -nd6_output(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m, - struct sockaddr_in6 *dst, struct rtentry *rt0) +nd6_resolve(struct ifnet *ifp, int is_gw, struct mbuf *m, + const struct sockaddr *sa_dst, u_char *desten, uint32_t *pflags) { struct llentry *ln = NULL; + const struct sockaddr_in6 *dst6; + + if (pflags != NULL) + *pflags = 0; + + dst6 = (const struct sockaddr_in6 *)sa_dst; /* discard the packet if IPv6 operation is disabled on the interface */ if ((ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED)) { @@ -1967,14 +1980,25 @@ nd6_output(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m, return (ENETDOWN); /* better error? */ } - if (IN6_IS_ADDR_MULTICAST(&dst->sin6_addr)) - goto sendpkt; - - if (nd6_need_cache(ifp) == 0) - goto sendpkt; + if (m != NULL && m->m_flags & M_MCAST) { + switch (ifp->if_type) { + case IFT_ETHER: + case IFT_FDDI: + case IFT_L2VLAN: + case IFT_IEEE80211: + case IFT_BRIDGE: + case IFT_ISO88025: + ETHER_MAP_IPV6_MULTICAST(&dst6->sin6_addr, + desten); + return (0); + default: + m_freem(m); + return (EAFNOSUPPORT); + } + } IF_AFDATA_RLOCK(ifp); - ln = nd6_lookup(&dst->sin6_addr, 0, ifp); + ln = nd6_lookup(&dst6->sin6_addr, 0, ifp); IF_AFDATA_RUNLOCK(ifp); /* @@ -1990,45 +2014,33 @@ nd6_output(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m, /* Fall back to slow processing path */ if (ln != NULL) LLE_RUNLOCK(ln); - return (nd6_output_lle(ifp, origifp, m, dst)); + return (nd6_resolve_slow(ifp, m, dst6, desten, pflags)); } -sendpkt: - if (ln != NULL) - LLE_RUNLOCK(ln); - return (nd6_output_ifp(ifp, origifp, m, dst)); + bcopy(&ln->ll_addr, desten, ifp->if_addrlen); + if (pflags != NULL) + *pflags = ln->la_flags; + LLE_RUNLOCK(ln); + return (0); } /* - * Output IPv6 packet - heavy version. - * Function assume that either - * 1) destination LLE does not exist, is invalid or stale, so - * ND6_EXCLUSIVE lock needs to be acquired - * 2) destination lle is provided (with ND6_EXCLUSIVE lock), - * in that case packets are queued in &chain. + * Do L2 address resolution for @sa_dst address. Stores found + * address in @desten buffer. Copy of lle ln_flags can be also + * saved in @pflags if @pflags is non-NULL. * + * Heavy version. + * Function assume that destination LLE does not exist, + * is invalid or stale, so ND6_EXCLUSIVE lock needs to be acquired. */ static int -nd6_output_lle(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m, - struct sockaddr_in6 *dst) +nd6_resolve_slow(struct ifnet *ifp, struct mbuf *m, + const struct sockaddr_in6 *dst, u_char *desten, uint32_t *pflags) { struct llentry *lle = NULL, *lle_tmp; - KASSERT(m != NULL, ("NULL mbuf, nothing to send")); - /* discard the packet if IPv6 operation is disabled on the interface */ - if ((ND_IFINFO(ifp)->flags & ND6_IFF_IFDISABLED)) { - m_freem(m); - return (ENETDOWN); /* better error? */ - } - - if (IN6_IS_ADDR_MULTICAST(&dst->sin6_addr)) - goto sendpkt; - - if (nd6_need_cache(ifp) == 0) - goto sendpkt; - /* * Address resolution or Neighbor Unreachability Detection * for the next hop. @@ -2072,23 +2084,18 @@ nd6_output_lle(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m, } } if (lle == NULL) { - if ((ifp->if_flags & IFF_POINTOPOINT) == 0 && - !(ND_IFINFO(ifp)->flags & ND6_IFF_PERFORMNUD)) { + if (!(ND_IFINFO(ifp)->flags & ND6_IFF_PERFORMNUD)) { m_freem(m); return (ENOBUFS); } - goto sendpkt; /* send anyway */ + + if (m != NULL) + m_freem(m); + return (ENOBUFS); } LLE_WLOCK_ASSERT(lle); - /* We don't have to do link-layer address resolution on a p2p link. */ - if ((ifp->if_flags & IFF_POINTOPOINT) != 0 && - lle->ln_state < ND6_LLINFO_REACHABLE) { - lle->ln_state = ND6_LLINFO_STALE; - nd6_llinfo_settimer_locked(lle, (long)V_nd6_gctimer * hz); - } - /* * The first time we send a packet to a neighbor whose entry is * STALE, we have to change the state to DELAY and a sets a timer to @@ -2107,8 +2114,13 @@ nd6_output_lle(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m, * (i.e. its link-layer address is already resolved), just * send the packet. */ - if (lle->ln_state > ND6_LLINFO_INCOMPLETE) - goto sendpkt; + if (lle->ln_state > ND6_LLINFO_INCOMPLETE) { + bcopy(&lle->ll_addr, desten, ifp->if_addrlen); + if (pflags != NULL) + *pflags = lle->la_flags; + LLE_WUNLOCK(lle); + return (0); + } /* * There is a neighbor cache entry, but no ethernet address @@ -2160,13 +2172,7 @@ nd6_output_lle(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *m, LLE_WUNLOCK(lle); } - return (0); - - sendpkt: - if (lle != NULL) - LLE_WUNLOCK(lle); - - return (nd6_output_ifp(ifp, origifp, m, dst)); + return (EWOULDBLOCK); } @@ -2192,15 +2198,12 @@ nd6_flush_holdchain(struct ifnet *ifp, struct ifnet *origifp, struct mbuf *chain /* * XXX - * note that intermediate errors are blindly ignored - but this is - * the same convention as used with nd6_output when called by - * nd6_cache_lladdr + * note that intermediate errors are blindly ignored */ return (error); } - -int +static int nd6_need_cache(struct ifnet *ifp) { /* @@ -2297,61 +2300,6 @@ nd6_rem_ifa_lle(struct in6_ifaddr *ia, int all) lltable_delete_addr(LLTABLE6(ifp), LLE_IFADDR, saddr); } -/* - * the callers of this function need to be re-worked to drop - * the lle lock, drop here for now - */ -int -nd6_storelladdr(struct ifnet *ifp, struct mbuf *m, - const struct sockaddr *dst, u_char *desten, uint32_t *pflags) -{ - struct llentry *ln; - - if (pflags != NULL) - *pflags = 0; - IF_AFDATA_UNLOCK_ASSERT(ifp); - if (m != NULL && m->m_flags & M_MCAST) { - switch (ifp->if_type) { - case IFT_ETHER: - case IFT_FDDI: - case IFT_L2VLAN: - case IFT_IEEE80211: - case IFT_BRIDGE: - case IFT_ISO88025: - ETHER_MAP_IPV6_MULTICAST(&SIN6(dst)->sin6_addr, - desten); - return (0); - default: - m_freem(m); - return (EAFNOSUPPORT); - } - } - - - /* - * the entry should have been created in nd6_store_lladdr - */ - IF_AFDATA_RLOCK(ifp); - ln = lla_lookup(LLTABLE6(ifp), 0, dst); - IF_AFDATA_RUNLOCK(ifp); - if ((ln == NULL) || !(ln->la_flags & LLE_VALID)) { - if (ln != NULL) - LLE_RUNLOCK(ln); - /* this could happen, if we could not allocate memory */ - m_freem(m); - return (1); - } - - bcopy(&ln->ll_addr, desten, ifp->if_addrlen); - if (pflags != NULL) - *pflags = ln->la_flags; - LLE_RUNLOCK(ln); - /* - * A *small* use after free race exists here - */ - return (0); -} - static void clear_llinfo_pqueue(struct llentry *ln) { |