When expiring a neighbour cache entry we may need to look up the associated
default router, which requires the nd6 read lock. To avoid an LOR, the nd6
lock should be acquired first.
X-MFC-With: r296063
Tested by: Larry Rosenman <ler@lerctr.org> (previous revision)
route caching for TCP, with some improvements. In particular, invalidate
the route cache if a new route is added, which might be a better match.
The cache is automatically invalidated if the old route is deleted.
Submitted by: Mike Karels
Reviewed by: gnn
Differential Revision: https://reviews.freebsd.org/D4306
Factor out nd6 and in6_attach initialization to their own files.
Also move destruction into those files though still called from
the central initialization.
Sponsored by: CK Software GmbH
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Reviewed by: gnn
Differential Revision: https://reviews.freebsd.org/D5033
This allows some simplification of its callers. No functional change
intended.
Tested by: Larry Rosenman (as part of a larger change)
MFC after: 1 month
pointer isn't NULL, it is safe, because we are handling IPV6_PKTINFO
socket option in this block of code. Also, use in6ifa_withaddr() instead
of ifa_withaddr().
The m_ext.ext_cnt pointer becomes a union. It can now hold the refcount
value itself. To tell that m_ext.ext_flags flag EXT_FLAG_EMBREF is used.
The first mbuf to attach a cluster stores the refcount. The further mbufs
to reference the cluster point at refcount in the first mbuf. The first
mbuf is freed only when the last reference is freed.
The benefit over refcounts stored in separate slabs is that now refcounts
of different, unrelated mbufs do not share a cache line.
For EXT_EXTREF mbufs the zone_ext_refcnt is no longer needed, and m_extadd()
becomes void, making widely used M_EXTADD macro safe.
For EXT_SFBUF mbufs the sf_ext_ref() is removed, which was an optimization
exactly against the cache aliasing problem with regular refcounting.
Discussed with: rrs, rwatson, gnn, hiren, sbruno, np
Reviewed by: rrs
Differential Revision: https://reviews.freebsd.org/D5396
Sponsored by: Netflix
This addresses a number of race conditions that can cause crashes as a
result of unsynchronized access to the list.
PR: 206904
Tested by: Larry Rosenman <ler@lerctr.org>,
Kevin Bowling <kevin.bowling@kev009.com>
MFC after: 2 months
Differential Revision: https://reviews.freebsd.org/D5315
Fix a panic that occurs when a vnet interface is unavailable at the time the
vnet jail referencing said interface is stopped.
Sponsored by: FIS Global, Inc.
back and harmize the use cases among RIB, IPFW, PF yet but it's also not
the scope of this work. Prevents instant panics on teardown and frees
the FIB bits again.
Sponsored by: The FreeBSD Foundation
There are number of radix consumers in kernel land (pf,ipfw,nfs,route)
with different requirements. In fact, first 3 don't have _any_ requirements
and first 2 does not use radix locking. On the other hand, routing
structure do have these requirements (rnh_gen, multipath, custom
to-be-added control plane functions, different locking).
Additionally, radix should not known anything about its consumers internals.
So, radix code now uses tiny 'struct radix_head' structure along with
internal 'struct radix_mask_head' instead of 'struct radix_node_head'.
Existing consumers still uses the same 'struct radix_node_head' with
slight modifications: they need to pass pointer to (embedded)
'struct radix_head' to all radix callbacks.
Routing code now uses new 'struct rib_head' with different locking macro:
RADIX_NODE_HEAD prefix was renamed to RIB_ (which stands for routing
information base).
New net/route_var.h header was added to hold routing subsystem internal
data. 'struct rib_head' was placed there. 'struct rtentry' will also
be moved there soon.
easier. Note: this is currently not in a usable state as certain
teardown parts are not called and the DOMAIN rework is missing.
More to come soon and find its way to head.
Obtained from: P4 //depot/user/bz/vimage/...
Sponsored by: The FreeBSD Foundation
The sctp6_ctlinput() function does not properly check the length of the packet
it receives from the ICMP6 input routine. This means that an attacker can craft
a packet that will cause a kernel panic.
When the kernel receives an ICMP6 error message with one of the types/codes
it handles, it calls icmp6_notify_error() to deliver it to the upper-level
protocol. icmp6_notify_error() cycles through the extension headers (if any)
to find the protocol number of the first non-extension header. It does NOT
verify the length of the non-extension header.
It passes information about the packet (including the actual packet) to the
upper-level protocol's pr_ctlinput function. In the case of SCTP for IPv6,
icmp6_notify_error() calls sctp6_ctlinput().
sctp6_ctlinput() assumes that the incoming packet contains a sufficiently-long
SCTP header and calls m_copydata() to extract a copy of that header. In turn,
m_copydata() assumes that the caller has already verified that the offset and
length parameters are correct. If they are incorrect, it will dereference a
NULL pointer and cause a kernel panic.
In short, no one is sufficiently verifying the input, and the result is a
kernel panic.
Submitted by: jtl
Security: SA-16:01.sctp
Move actual rte selection process from rtalloc_mpath_fib()
to the rt_path_selectrte() function. Add public
rt_mpath_select() to use in fibX_lookup_ functions.
in6_selectsrc() has 2 class of users: socket-based one (raw/udp/pcb/etc) and
socket-less (ND code). The main reason for that change is inability to
specify non-default FIB for callers w/o socket since (internally) inpcb
is used to determine fib.
As as result, add 2 wrappers for in6_selectsrc() (making in6_selectsrc()
static):
1) in6_selectsrc_socket() for the former class. Embed scope_ambiguous check
along with returning hop limit when needed.
2) in6_selectsrc_addr() for the latter case. Add 'fibnum' argument and
pass IPv6 address w/ explicitly specified scope as separate argument.
Reviewed by: ae (previous version)
This check was added in initial? netinet6/ import
back in 1999 (r53541).
It effectively became unnecessary after 'address/prefix clean-ups'
KAME commit 90ff8792e676132096a440dd787f99a5a5860ee8 (github) in 2001
(merged to FreeBSD in r78064) where prefix check was added to
nd6_prefix_onlink(). Similar IPv4 check (in_addroute() was added
in r137628).
Additionally, the right plance for this (or similar) check is the prefix
addition code (nd6_prefix_onlink(), nd6_prefix_onlink_rtrequest(),
in_addprefix() or rtinit()), but not the generic radix insert routine.
entries data in unified format.
There are control plane functions that require information other than
just next-hop data (e.g. individual rtentry fields like flags or
prefix/mask). Given that the goal is to avoid rte reference/refcounting,
re-use rt_addrinfo structure to store most rte fields. If caller wants
to retrieve key/mask or gateway (which are sockaddrs and are allocated
separately), it needs to provide sufficient-sized sockaddrs structures
w/ ther pointers saved in passed rt_addrinfo.
Convert:
* lltable new records checks (in_lltable_rtcheck(),
nd6_is_new_addr_neighbor().
* rtsock pre-add/change route check.
* IPv6 NS ND-proxy check (RADIX_MPATH code was eliminated because
1) we don't support RTF_ANNOUNCE ND-proxy for networks and there should
not be multiple host routes for such hosts 2) if we have multiple
routes we should inspect them (which is not done). 3) the entire idea
of abusing KRT as storage for ND proxy seems odd. Userland programs
should be used for that purpose).
in6_selectif().
The main task of in6_selectsrc() is to return IPv6 SAS (along with
output interface used for scope checks). No data-path code uses
route argument for caching. The only users are icmp6 (reflect code),
ND6 ns/na generation code. All this fucntions are control-plane, so
there is no reason to try to 'optimize' something by passing cached
route into to ip6_output(). Given that, simplify code by eliminating
in6_selectsrc() 'struct route_in6' argument. Since in6_selectif() is
used only by in6_selectsrc(), eliminate its 'struct route_in6' argument,
too. While here, reshape rte-related code inside in6_selectif() to
free lookup result immediately after saving all the needed fields.
Add ro_mtu field to 'struct route' to be able to pass lookup MTU back to
the caller.
Currently, ip6_getpmtu() has 2 totally different use cases:
1) control plane (IPV6_PATHMTU req), where we just need to calculate MTU
and return it, w/o any reusability.
2) Actual ip6_output() data path where we (nearly) always use the provided
route lookup data. If this data is not 'valid' we need to perform another
lookup and save the result (which cannot be re-used by ip6_output()).
Given that, handle 1) by calling separate function doing rte lookup itself.
Resulting MTU is calculated by (newly-added) ip6_calcmtu() used by both
ip6_getpmtu_ctl() and ip6_getpmtu().
For 2) instead of storing ref'ed rte, store mtu (the only needed data
from the lookup result) inside newly-added ro_mtu field.
'struct route' was shrinked by 8(or 4 bytes) in r292978. Grow it again
by 4 bytes. New ro_mtu field will be used in other places like
ip/tcp_output (EMSGSIZE handling from output routines).
Reviewed by: ae
Add if_requestencap() interface method which is capable of calculating
various link headers for given interface. Right now there is support
for INET/INET6/ARP llheader calculation (IFENCAP_LL type request).
Other types are planned to support more complex calculation
(L2 multipath lagg nexthops, tunnel encap nexthops, etc..).
Reshape 'struct route' to be able to pass additional data (with is length)
to prepend to mbuf.
These two changes permits routing code to pass pre-calculated nexthop data
(like L2 header for route w/gateway) down to the stack eliminating the
need for other lookups. It also brings us closer to more complex scenarios
like transparently handling MPLS nexthops and tunnel interfaces.
Last, but not least, it removes layering violation introduced by flowtable
code (ro_lle) and simplifies handling of existing if_output consumers.
ARP/ND changes:
Make arp/ndp stack pre-calculate link header upon installing/updating lle
record. Interface link address change are handled by re-calculating
headers for all lles based on if_lladdr event. After these changes,
arpresolve()/nd6_resolve() returns full pre-calculated header for
supported interfaces thus simplifying if_output().
Move these lookups to separate ether_resolve_addr() function which ether
returs error or fully-prepared link header. Add <arp|nd6_>resolve_addr()
compat versions to return link addresses instead of pre-calculated data.
BPF changes:
Raw bpf writes occupied _two_ cases: AF_UNSPEC and pseudo_AF_HDRCMPLT.
Despite the naming, both of there have ther header "complete". The only
difference is that interface source mac has to be filled by OS for
AF_UNSPEC (controlled via BIOCGHDRCMPLT). This logic has to stay inside
BPF and not pollute if_output() routines. Convert BPF to pass prepend data
via new 'struct route' mechanism. Note that it does not change
non-optimized if_output(): ro_prepend handling is purely optional.
Side note: hackish pseudo_AF_HDRCMPLT is supported for ethernet and FDDI.
It is not needed for ethernet anymore. The only remaining FDDI user is
dev/pdq mostly untouched since 2007. FDDI support was eliminated from
OpenBSD in 2013 (sys/net/if_fddisubr.c rev 1.65).
Flowtable changes:
Flowtable violates layering by saving (and not correctly managing)
rtes/lles. Instead of passing lle pointer, pass pointer to pre-calculated
header data from that lle.
Differential Revision: https://reviews.freebsd.org/D4102
the wrapper functions as used in r252511. We can directly use the
locking macros.
Reviewed by: jtl, rwatson
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D4731
bridge(4) interfaces have an if_type of IFT_BRIDGE, rather than
IFT_ETHER, even though they only support Ethernet-style links. This
caused in6_if2idlen to emit an "unknown link type (209)" warning to
the console every time it was called. Add IFT_BRIDGE to the case
statement in the appropriate place, indicating that it uses the same
IPv6 address format as other Ethernet-like interfaces.
MFC after: 1 week
Reported by: Matthew D. Fuller (fullermd over-yonder.net),
Kevin Bowling (kevin.bowling kev009.com)
MFC after: 13 days
X-MFC with: r292601
Sponsored by: The FreeBSD Foundation
on vnet enabled jail shutdown. Call the provided cleanup
routines for IP versions 4 and 6 to plug these leaks.
Sponsored by: The FreeBSD Foundation
MFC atfer: 2 weeks
Reviewed by: gnn
Differential Revision: https://reviews.freebsd.org/D4530
Before the change, things like lle state were queried via
SIOCGNBRINFO_IN6 by ndp(8) for _each_ lle entry in dump.
This ioctl was added in 1999, probably to avoid touching rtsock code.
This change maps SIOCGNBRINFO_IN6 data to standard rtsock dump the
following way:
expire (already) maps to rtm_rmx.rmx_expire
isrouter -> rtm_flags & RTF_GATEWAY
asked -> rtm_rmx.rmx_pksent
state -> rtm_rmx.rmx_state (maps to rmx_weight via define)
Reviewed by: ae
When using lagg failover mode neither Gratuitous ARP (IPv4) or Unsolicited
Neighbour Advertisements (IPv6) are sent to notify other nodes that the
address may have moved.
This results is slow failover, dropped packets and network outages for the
lagg interface when the primary link goes down.
We now use the new if_link_state_change_cond with the force param set to
allow lagg to force through link state changes and hence fire a
ifnet_link_event which are now monitored by rip and nd6.
Upon receiving these events each protocol trigger the relevant
notifications:
* inet4 => Gratuitous ARP
* inet6 => Unsolicited Neighbour Announce
This also fixes the carp IPv6 NA's that stopped working after r251584 which
added the ipv6_route__llma route.
The new behavour can be controlled using the sysctls:
* net.link.ether.inet.arp_on_link
* net.inet6.icmp6.nd6_on_link
Also removed unused param from lagg_port_state and added descriptions for the
sysctls while here.
PR: 156226
MFC after: 1 month
Sponsored by: Multiplay
Differential Revision: https://reviews.freebsd.org/D4111
Certain interfaces (e.g. pfsync0) do not have ip6 addresses (in other words,
ifp->if_afdata[AF_INET6] is NULL). Ensure we don't panic when the MTU is
updated.
pfsync interfaces will never have ip6 support, because it's explicitly disabled
in in6_domifattach().
PR: 205194
Reviewed by: melifaro, hrs
Differential Revision: https://reviews.freebsd.org/D4522
LLE structure is mostly unchanged during its lifecycle: there are only 2
things relevant for fast path lookup code:
1) link-level address change. Since r286722, these updates are performed
under AFDATA WLOCK.
2) Some sort of feedback indicating that this particular entry is used so
we send NS to perform reachability verification instead of expiring entry.
The only signal that is needed from fast path is something like binary
yes/no.
The latter is solved by the following changes:
Special r_skip_req (introduced in D3688) value is used for fast path feedback.
It is read lockless by fast path, but updated under req_mutex mutex. If this
field is non-zero, then fast path will acquire lock and set it back to 0.
After transitioning to STALE state, callout timer is armed to run each
V_nd6_delay seconds to make sure that if packet was transmitted at the start
of given interval, we would be able to switch to PROBE state in V_nd6_delay
seconds as user expects.
(in STALE state) timer is rescheduled until original V_nd6_gctimer expires
keeping lle in STALE state (remaining timer value stored in lle_remtime).
(in STALE state) timer is rescheduled if packet was transmitted less that
V_nd6_delay seconds ago to make sure we transition to PROBE state exactly
after V_n6_delay seconds.
As a result, all packets towards lle in REACHABLE/STALE/PROBE states are handled
by fast path without acquiring lle read lock.
Differential Revision: https://reviews.freebsd.org/D3780
ip_dooptions(), icmp6_redirect_input(), in6_lltable_rtcheck(),
in6p_lookup_mcast_ifp() and in6_selecthlim() use new routing api.
Eliminate now-unused ip_rtaddr().
Fix lookup key fib6_lookup_nh_basic() which was lost diring merge.
Make fib6_lookup_nh_basic() and fib6_lookup_nh_extended() always
return IPv6 destination address with embedded scope. Currently
rw_gateway has it scope embedded, do the same for non-gatewayed
destinations.
Sponsored by: Yandex LLC
Vast majority of rtalloc(9) users require only basic info from
route table (e.g. "does the rtentry interface match with the interface
I have?". "what is the MTU?", "Give me the IPv4 source address to use",
etc..).
Instead of hand-rolling lookups, checking if rtentry is up, valid,
dealing with IPv6 mtu, finding "address" ifp (almost never done right),
provide easy-to-use API hiding all the complexity and returning the
needed info into small on-stack structure.
This change also helps hiding route subsystem internals (locking, direct
rtentry accesses).
Additionaly, using this API improves lookup performance since rtentry is not
locked.
(This is safe, since all the rtentry changes happens under both radix WLOCK
and rtentry WLOCK).
Sponsored by: Yandex LLC
* When processing a cookie, use the number of
streams announced in the INIT-ACK.
* When sending an INIT-ACK for an existing
association, use the value from the association,
not from the end-point.
MFC after: 1 week
a reply to the MLDv2 General Query. In case when router has a lot of
multicast groups, the reply can take several packets due to MTU limitation.
Also we have a limit MLD_MAX_RESPONSE_BURST == 4, that limits the number
of packets we send in one shot. Then we recalculate the timer value and
schedule the remaining packets for sending.
The problem is that when we call mld_v2_dispatch_general_query() to send
remaining packets, we queue new reply in the same mbuf queue. And when
number of packets is bigger than MLD_MAX_RESPONSE_BURST, we get endless
reply of MLDv2 reports.
To fix this, add the check for remaining packets in the queue.
PR: 204831
MFC after: 1 week
Sponsored by: Yandex LLC
by filter function instead of picking into routing table details in
each consumer.
Remove now-unused rt_expunge() (eliminating last external RTF_RNH_LOCKED
user).
This simplifies future nexthops/mulitipath changes and rtrequest1_fib()
locking refactoring.
Actual changes:
Add "rt_chain" field to permit rte grouping while doing batched delete
from routing table (thus growing rte 200->208 on amd64).
Add "rti_filter" / "rti_filterdata" / "rti_spare" fields to rt_addrinfo
to pass filter function to various routing subsystems in standard way.
Convert all rt_expunge() customers to new rt_addinfo-based api and eliminate
rt_expunge().
Use hhook(9) framework to achieve ability of loading and unloading
if_enc(4) kernel module. INET and INET6 code on initialization registers
two helper hooks points in the kernel. if_enc(4) module uses these helper
hook points and registers its hooks. IPSEC code uses these hhook points
to call helper hooks implemented in if_enc(4).
Analogously to r291040, in6_mc_get recurses on if_addr_lock if the
M_NOWAIT allocation fails. The fix is the same.
Suggested by: Andrey V. Elsukov
Reviewed by: jhb (ip4 version)
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D4138 (ip4 version)
new return codes of -1 were mistakenly being considered "true". Callout_stop
now returns -1 to indicate the callout had either already completed or
was not running and 0 to indicate it could not be stopped. Also update
the manual page to make it more consistent no non-zero in the callout_stop
or callout_reset descriptions.
MFC after: 1 Month with associated callout change.
This is required for fragments and encapsulated data (eg tunneling) to be redistributed
to the RSS bucket based on the eventual IPv6 header and protocol (TCP, UDP, etc) header.
* Add an mbuf tag with the state of IPv6 options parsing before the frame is queued
into the direct dispatch handler;
* Continue processing and complete the frame reception in the correct RSS bucket /
netisr context.
Testing results are in the phabricator review.
Differential Revision: https://reviews.freebsd.org/D3563
Submitted by: Tiwei Bie <btw@mail.ustc.edu.cn>
For case (7) (new entry) nothing has to be done except lle_event.
Invoke this event directly from "create new lle" code block.
For case (4) (existing entry, same mac) useless mac update was performed,
along with LLENTRY_RESOLVED lle_event. There was no sense in doing that,
since nothing really had changed. Simply avoid this condition instead.
Given that, condition was simplified to (3),(5) states which can be merged
with previous block.
Effectively it always returned NULL so SAS was always performed and
sometimes the result might have been different.
Fix state machine change accidentally introduced in r287985:
state (4) inside nd6_cache_lladdr() (existing entry got nd message
with the same lladdress) started to cause lle state transition to STALE
instead of no-action.
catches cases that DAD probes cannot be sent because of
IFF_UP && !IFF_DRV_RUNNING.
- nd6_dad_starttimer() now calls nd6_dad_ns_output(), instead of
calling it before nd6_dad_starttimer().
- Do not release an entry in dadq when a duplicate entry is being
added.
Currently we perform crypto requests for IPSEC synchronous for most of
crypto providers (software, aesni) and only VIA padlock calls crypto
callback asynchronous. In synchronous mode it is possible, that security
policy will be removed during the processing crypto request. And crypto
callback will release the last reference to SP. Then upon return into
ipsec[46]_process_packet() IPSECREQUEST_UNLOCK() will be called to already
freed request. To prevent this we will take extra reference to SP.
PR: 201876
Sponsored by: Yandex LLC
Initially function was introduced in r53541 (KAME initial commit) to
"provide hints from upper layer protocols that indicate a connection
is making "forward progress"" (quote from RFC 2461 7.3.1 Reachability
Confirmation).
However, it was converted to do nothing (e.g. just return) in r122922
(tcp_hostcache implementation) back in 2003. Some defines were moved
to tcp_var.h in r169541. Then, it was broken (for non-corner cases)
by r186119 (L2<>L3 split) in 2008 (NULL ifp in nd6_lookup). So,
right now this code is broken and has no "real" base users.
Differential Revision: https://reviews.freebsd.org/D3699
instead of old "ignore-and-return 0" in r287789. This broke arp -da /
ndp -cn behavior (they exit on rtsock command failure). Fix this by
translating LLE_IFADDR to RTM_PINNED flag, passing it to userland and
making arp/ndp ignore these entries in batched delete.
MFC after: 2 weeks
e.g., based on wrong "next header" assumptions (which does not have to point to
the upper layer protocol), or using hard-coded UDP instead of UDP or UDP-Lite
possibly switching protocols. Fix those cases for UDP-Lite to work correctly.
PR: 202788
Submitted by: Tiwei Bie (btw mail.ustc.edu.cn) [parts]
Reviewed by: gnn, Tiwei Bie (btw mail.ustc.edu.cn),
kevlo (earlier version)
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D3686
function. The change is mostly mechanical with the following exception:
Last piece of nd6_resolve_slow() was refactored: ND6_LLINFO_PERMANENT
condition was removed as always-true, explicit ND6_LLINFO_NOSTATE ->
ND6_LLINFO_INCOMPLETE state transition was removed as duplicate.
Reviewed by: ae
Sponsored by: Yandex LLC
* Since new extries are now allocated explicitly, fill in
all the necessary fields for lle _before_ attaching it to the table.
* Remove ND6_LLINFO_INCOMPLETE check which was unused even in
first KAME merge (r53541).
* After that, the only new state that function can set, was
ND6_LLINFO_STALE. Given everything above, simplify logic besides
do_update and is_newentry.
* Fix nd_resolve() comment.
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
* Move isRouter calculation code to separate nd6_is_router() function.
* Make nd6_cache_lladdr() return void: its return value hasn't been used
since r53541 KAME import in 1999.
Sponsored by: Yandex LLC
On receipt of a redirect message, install an interface route for the
redirected destination. On removal of the corresponding Neighbor Cache
entry, remove the interface route.
This requires changes in rtredirect_fib() to cope with an AF_LINK
address for the gateway and with the absence of RTF_GATEWAY.
This fixes the "Redirected On-Link" test cases in the Tahi IPv6 Ready Logo
Phase 2 test suite.
Unrelated to the above, fix a recursion on the radix node head lock
triggered by the Tahi Redirected to Alternate Router test cases.
When I first wrote this patch in October 2012, all Section 2
(Neighbor Discovery) test cases passed on 10-CURRENT, 9-STABLE,
and 8-STABLE. cem@ recently rebased the 10.x patch onto head and reported
that it passes Tahi. (Thanks!)
These other test cases also passed in 2012:
* the RTF_MODIFIED case, with IPv4 and IPv6 (using a
RTF_HOST|RTF_GATEWAY route for the destination)
* the redirected-to-self case, with IPv4 and IPv6
* a valid IPv4 redirect
All testing in 2012 was done with WITNESS and INVARIANTS.
Tested by: EMC / Isilon Storage Division via Conrad Meyer (cem) in 2015,
Mark Kelley <mark_kelley@dell.com> in 2012,
TC Telkamp <terence_telkamp@dell.com> in 2012
PR: 152791
Reviewed by: melifaro (current rev), bz (earlier rev)
Approved by: kib (mentor)
MFC after: 1 month
Relnotes: yes
Sponsored by: Dell Inc.
Differential Revision: https://reviews.freebsd.org/D3602
without holding afdata wlock
* convert per-af delete_address callback to global lltable_delete_entry() and
more low-level "delete this lle" per-af callback
* fix some bugs/inconsistencies in IPv4/IPv6 ifscrub procedures
Sponsored by: Yandex LLC
Differential Revision: https://reviews.freebsd.org/D3573
This mirrors the basic IPv4 implementation - IPv6 packets under RSS
now are checked for a correct RSS hash and if one isn't provided,
it's done in software.
This only handles the initial receive - it doesn't yet handle
reinjecting / rehashing packets after being decapsulated from
various tunneling setups. That'll come in some follow-up work.
For non-RSS users, this is almost a giant no-op.
It does change a couple of ipv6 methods to use const mbuf * instead of
mbuf * but it doesn't have any functional changes.
So, the following now occurs:
* If the NIC doesn't do any RSS hashing, it's all done in software.
Single-queue, non-RSS NICs will now have the RX path distributed
into multiple receive netisr queues.
* If the NIC provides the wrong hash (eg only IPv6 hash when we needed
an IPv6 TCP hash, or IPv6 UDP hash when we expected IPv6 hash)
then the hash is recalculated.
* .. if the hash is recalculated, it'll end up being injected into
the correct netisr queue for v6 processing.
Submitted by: Tiwei Bie <btw@mail.ustc.edu.cn>
Differential Revision: https://reviews.freebsd.org/D3504
do not do what one would expect by name. Prefix them with "udp_"
to at least obviously limit the scope.
This is a non-functional change.
Reviewed by: gnn, rwatson
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D3505
This isn't yet linked into the receive/transmit paths anywhere just yet.
This is part of a GSoC 2015 project.
Submitted by: Tiwei Bie <btw@mail.ustc.edu.cn>
Reviewed by: hiren, gnn
Differential Revision: https://reviews.freebsd.org/D3423
interface but in6if_do_dad() already had a check for IFF_LOOPBACK.
- Remove in6if_do_dad() check in in6_broadcast_ifa(). An address
which needs DAD always has IN6_IFF_TENTATIVE there.
- in6if_do_dad() now returns EAGAIN when the interface is not ready
since DAD callout handler ignores such an interface.
- In DAD callout handler, mark an address as IN6_IFF_TENTATIVE
when the interface has ND6_IFF_IFDISABLED. And Do IFF_UP and
IFF_DRV_RUNNING check consistently when DAD is required.
- draft-ietf-6man-enhanced-dad is now published as RFC 7527.
- Fix some typos.
Before that, the logic besides lle_create() was the following:
return existing if found, create if not. This behaviour was error-prone
since we had to deal with 'sudden' static<>dynamic lle changes.
This commit fixes bunch of different issues like:
- refcount leak when lle is converted to static.
Simple check case:
console 1:
while true;
do for i in `arp -an|awk '$4~/incomp/{print$2}'|tr -d '()'`;
do arp -s $i 00:22:44:66:88:00 ; arp -d $i;
done;
done
console 2:
ping -f any-dead-host-in-L2
console 3:
# watch for memory consumption:
vmstat -m | awk '$1~/lltable/{print$2}'
- possible problems in arptimer() / nd6_timer() when dropping/reacquiring
lock.
New logic explicitly handles use-or-create cases in every lla_create
user. Basically, most of the changes are purely mechanical. However,
we explicitly avoid using existing lle's for interface/static LLE records.
* While here, call lle_event handlers on all real table lle change.
* Create lltable_free_entry() calling existing per-lltable
lle_free_t callback for entry deletion
This permits us having all (not fully true yet) all the info
needed in lookup process in first 64 bytes of 'struct llentry'.
struct llentry layout:
BEFORE:
[rwlock .. state .. state .. MAC ] (lle+1) [sockaddr_in[6]]
AFTER
[ in[6]_addr MAC .. state .. rwlock ]
Currently, address part of struct llentry has only 16 bytes for the key.
However, lltable does not restrict any custom lltable consumers with long
keys use the previous approach (store key at (lle+1)).
Sponsored by: Yandex LLC
* Split lltable_init() into lltable_allocate_htbl() (alloc
hash table with default callbacks) and lltable_link() (
links any lltable to the list).
* Switch from LLTBL_HASHTBL_SIZE to per-lltable hash size field.
* Move lltable setup to separate functions in in[6]_domifattach.
differences between projects/routing and HEAD.
This commit tries to keep code logic the same while changing underlying
code to use unified callbacks.
* Add llt_foreach_entry method to traverse all entries in given llt
* Add llt_dump_entry method to export particular lle entry in sysctl/rtsock
format (code is not indented properly to minimize diff). Will be fixed
in the next commits.
* Add llt_link_entry/llt_unlink_entry methods to link/unlink particular lle.
* Add llt_fill_sa_entry method to export address in the lle to sockaddr
format.
* Add llt_hash method to use in generic hash table support code.
* Add llt_free_entry method which is used in llt_prefix_free code.
* Prepare for fine-grained locking by separating lle unlink and deletion in
lltable_free() and lltable_prefix_free().
* Provide lltable_get<ifp|af>() functions to reduce direct 'struct lltable'
access by external callers.
* Remove @llt agrument from lle_free() lle callback since it was unused.
* Temporarily add L3_CADDR() macro for 'const' sockaddr typecasting.
* Switch to per-af hashing code.
* Rename LLE_FREE_LOCKED() callback from in[6]_lltable_free() to
in_[6]lltable_destroy() to avoid clashing with llt_free_entry() method.
Update description from these functions.
* Use unified lltable_free_entry() function instead of per-af one.
Reviewed by: ae
* Move interface route cleanup to route.c:rt_flushifroutes()
* Convert most of "for (fibnum = 0; fibnum < rt_numfibs; fibnum++)" users
to use new rt_foreach_fib() instead of hand-rolling cycles.
* Move lle creation/deletion from lla_lookup to separate functions:
lla_lookup(LLE_CREATE) -> lla_create
lla_lookup(LLE_DELETE) -> lla_delete
lla_create now returns with LLE_EXCLUSIVE lock for lle.
* Provide typedefs for new/existing lltable callbacks.
Reviewed by: ae
Do not pass 'dst' sockaddr to ip[6]_mloopback:
- We have explicit check for AF_INET in ip_output()
- We assume ip header inside passed mbuf in ip_mloopback
- We assume ip6 header inside passed mbuf in ip6_mloopback
- The existing TCP INP_INFO lock continues to protect the global inpcb list
stability during full list traversal (e.g. tcp_pcblist()).
- A new INP_LIST lock protects inpcb list actual modifications (inp allocation
and free) and inpcb global counters.
It allows to use TCP INP_INFO_RLOCK lock in critical paths (e.g. tcp_input())
and INP_INFO_WLOCK only in occasional operations that walk all connections.
PR: 183659
Differential Revision: https://reviews.freebsd.org/D2599
Reviewed by: jhb, adrian
Tested by: adrian, nitroboost-gmail.com
Sponsored by: Verisign, Inc.
o remove disabled code;
o if nexthop address is link-local, use embedded scope zone id to
determine outgoing interface;
o properly fill ro_dst before doing route lookup;
o remove LLE lookup, instead check rt_flags for RTF_GATEWAY bit.
Sponsored by: Yandex LLC
ip_encap already has inspected mbuf's data, at least an IP header.
And it is safe to use mtod() and do direct access to needed fields.
Add M_ASSERTPKTHDR() to gif_encapcheck(), since the code expects that
mbuf has a packet header.
Move the code from gif_validate[46] into in[6]_gif_encapcheck(), also
remove "martian filters" checks. According to RFC 4213 it is enough to
verify that the source address is the address of the encapsulator, as
configured on the decapsulator.
Reviewed by: melifaro
Obtained from: Yandex LLC
Sponsored by: Yandex LLC
Both are used to protect access to IP addresses lists and they can be
acquired for reading several times per packet. To reduce lock contention
it is better to use rmlock here.
Reviewed by: gnn (previous version)
Obtained from: Yandex LLC
Sponsored by: Yandex LLC
Differential Revision: https://reviews.freebsd.org/D3149
lock on the INP before calling the tunnel protocol, else a LOR
may occur (it does with SCTP for sure). Instead we must acquire a
ref count and release the lock, taking care to allow for the case
where the UDP socket has gone away and *not* unlocking since the
refcnt decrement on the inp will do the unlock in that case.
Reviewed by: tuexen
MFC after: 3 weeks
years for head. However, it is continuously misused as the mpsafe argument
for callout_init(9). Deprecate the flag and clean up callout_init() calls
to make them more consistent.
Differential Revision: https://reviews.freebsd.org/D2613
Reviewed by: jhb
MFC after: 2 weeks
gif(4) interface. Add new option "ignore_source" for gif(4) interface.
When it is enabled, gif's encapcheck function requires match only for
packet's destination address.
Differential Revision: https://reviews.freebsd.org/D2004
Obtained from: Yandex LLC
MFC after: 2 weeks
Sponsored by: Yandex LLC
because a link where looped back NS messages are permanently observed
does not work with either NDP or ARP for IPv4.
- draft-ietf-6man-enhanced-dad is now RFC 7527.
Discussed with: hiren
MFC after: 3 days
When we are passing mbuf to IPSec processing via ipsec[46]_process_packet(),
we hold one reference to security policy and release it just after return
from this function. But IPSec processing can be deffered and when we release
reference to security policy after ipsec[46]_process_packet(), user can
delete this security policy from SPDB. And when IPSec processing will be
done, xform's callback function will do access to already freed memory.
To fix this move KEY_FREESP() into callback function. Now IPSec code will
release reference to SP after processing will be finished.
Differential Revision: https://reviews.freebsd.org/D2324
No objections from: #network
Sponsored by: Yandex LLC
public_ifa6 may be set to NULL after taking a reference to a previous
address list element. Instead, only take the reference after leaving the
loop but before releasing the address list lock.
Differential Revision: https://reviews.freebsd.org/D2253
Reviewed by: ae
MFC after: 2 weeks
interface index is specified as zero, the system should select the
interface to use for outgoing multicast packets. Even the comment
for the in6p_set_multicast_if() function says about index of zero.
But in fact for zero index the function just returns EADDRNOTAVAIL.
I.e. if you first set some interface and then will try reset it
with zero ifindex, you will get EADDRNOTAVAIL.
Reset im6o_multicast_ifp to NULL when interface index specified as
zero. Also return EINVAL in case when ifnet_byindex() returns NULL.
This will be the same behaviour as when ifindex is bigger than
V_if_index. And return EADDRNOTAVAIL only when interface is not
multicast capable.
Reported by: Olivier Cochard-Labbé
MFC after: 2 weeks
Sponsored by: Yandex LLC
It is acceptable that the size can be equal to MCLBYTES. In the later
KAME's code this check has been moved under DIAGNOSTIC ifdef, because
the size of NA and NS is much smaller than MCLBYTES. So, it is safe to
replace the check with KASSERT.
PR: 199304
Discussed with: glebius
MFC after: 1 week
Defer the packet size check until after the firewall has had a look at it. This
means that the firewall now has the opportunity to (re-)fragment an oversized
packet.
Differential Revision: https://reviews.freebsd.org/D1815
Reviewed by: ae
Approved by: gnn (mentor)
contain kernel pointers, and instead has interface index.
Bump __FreeBSD_version for that change.
o Now, netstat/mroute6.c no longer needs to kvm_read(3) struct ifnet, and
no longer needs to include if_var.h
Note that this change is far from being a complete move of IPv6 multicast
routing to a proper API. Other structures are still dumped into their
sysctls as is, requiring userland application to #define _KERNEL when
including ip6_mroute.h and then call kvm_read(3) to gather all bits and
pieces. But fixing this is out of scope of the opaque ifnet project.
Sponsored by: Nginx, Inc.
Sponsored by: Netflix
We'll just fall into the same local delivery block under the
'if (m->m_flags & M_FASTFWD_OURS)'.
Suggested by: ae
Differential Revision: https://reviews.freebsd.org/D2225
Approved by: gnn (mentor)
When forwarding fragmented IPv6 packets and filtering with PF we
reassemble and refragment. That means we generate new fragment headers
and a new fragment ID.
We already save the fragment IDs so we can do the reassembly so it's
straightforward to apply the incoming fragment ID on the refragmented
packets.
Differential Revision: https://reviews.freebsd.org/D2188
Approved by: gnn (mentor)
- Add no_dad and ignoreloop per-IF knob. no_dad disables DAD completely,
and ignoreloop is to prevent infinite loop in loopback probing state when
loopback is permanently expected.
When several threads are trying to send datagram to the same destination,
but fragmentation is disabled and datagram size exceeds link MTU,
ip6_output() calls pfctlinput2(PRC_MSGSIZE). It does notify all
sockets wanted to know MTU to this destination. And since all threads
hold PCB lock while sending, taking the lock for each PCB in the
in6_pcbnotify() leads to deadlock.
RFC 3542 p.11.3 suggests notify all application wanted to receive
IPV6_PATHMTU ancillary data for each ICMPv6 packet too big message.
But it doesn't require this, when we don't receive ICMPv6 message.
Change ip6_notify_pmtu() function to be able use it directly from
ip6_output() to notify only one socket, and to notify all sockets
when ICMPv6 packet too big message received.
PR: 197059
Differential Revision: https://reviews.freebsd.org/D1949
Reviewed by: no objection from #network
Obtained from: Yandex LLC
MFC after: 1 week
Sponsored by: Yandex LLC
to initialize mbuf's fibnum. Uninitialized fibnum value can lead to
panic in the routing code. Currently we use only RT_DEFAULT_FIB value
for initialization.
Differential Revision: https://reviews.freebsd.org/D1998
Reviewed by: hrs (previous version)
Sponsored by: Yandex LLC
draft-ietf-6man-enhanced-dad-13.
This basically adds a random nonce option (RFC 3971) to NS messages
for DAD probe to detect a looped back packet. This looped back packet
prevented DAD on some pseudo-interfaces which aggregates multiple L2 links
such as lagg(4).
The length of the nonce is set to 6 bytes. This algorithm can be disabled by
setting net.inet6.ip6.dad_enhanced sysctl to 0 in a per-vnet basis.
Reported by: hiren
Reviewed by: ae
Differential Revision: https://reviews.freebsd.org/D1835
represents a context.
- Preserve name 'struct mld_ifinfo' for a new structure, that will be stable
API between userland and kernel.
- Make sysctl_mld_ifinfo() return the new 'struct mld_ifinfo', instead of
old one, which had a bunch of internal kernel structures in it.
Sponsored by: Netflix
Sponsored by: Nginx, Inc.
and arp were being used. They basically would pass in the
mutex to the callout_init. Because they used this method
to the callout system, it was possible to "stop" the callout.
When flushing the table and you stopped the running callout, the
callout_stop code would return 1 indicating that it was going
to stop the callout (that was about to run on the callout_wheel blocked
by the function calling the stop). Now when 1 was returned, it would
lower the reference count one extra time for the stopped timer, then
a few lines later delete the memory. Of course the callout_wheel was
stuck in the lock code and would then crash since it was accessing
freed memory. By using callout_init(c, 1) we always get a 0 back
and the reference counting bug does not rear its head. We do have
to make a few adjustments to the callouts themselves though to make
sure it does the proper thing if rescheduled as well as gets the lock.
Commented upon by hiren and sbruno
See Phabricator D1777 for more details.
Commented upon by hiren and sbruno
Reviewed by: adrian, jhb and bz
Sponsored by: Netflix Inc.
bits.
The motivation here is to eventually teach netisr and potentially
other networking subsystems a bit more about how RSS work queues / buckets
are configured so things have a hope of auto-configuring in the future.
* net/rss_config.[ch] takes care of the generic bits for doing
configuration, hash function selection, etc;
* topelitz.[ch] is now in net/ rather than netinet/;
* (and would be in libkern if it didn't directly include RSS_KEYSIZE;
that's a later thing to fix up.)
* netinet/in_rss.[ch] now just contains the IPv4 specific methods;
* and netinet/in6_rss.[ch] now just contains the IPv6 specific methods.
This should have no functional impact on anyone currently using
the RSS support.
Differential Revision: D1383
Reviewed by: gnn, jfv (intel driver bits)
use ifqueue at all. Second, there is no point in this lockless check.
Either positive or negative result of the check could be incorrect after
a tick.
Sponsored by: Nginx, Inc.
handle it in arc_output() instead of nd6_storelladdr().
* Remove IFT_ARCNET check from arpresolve() since arc_output() does not
use arpresolve() to handle broadcast/multicast. This check was there
since r84931. It looks like it was not used since r89099 (initial
import of Arcnet support where multicast is handled separately).
* Remove IFT_IEEE1394 case from nd6_storelladdr() since firewire_output()
calles nd6_storelladdr() for unicast addresses only.
* Remove IFT_ARCNET case from nd6_storelladdr() since arc_output() now
handles multicast by itself.
As a result, we have the following pattern: all non-ethernet-style
media have their own multicast map handling inside their appropriate
routines. On the other hand, arpresolve() (and nd6_storelladdr()) which
meant to be 'generic' ones de-facto handles ethernet-only multicast maps.
MFC after: 3 weeks
hold mbuf chain instead of calling full-blown nd6_output_lle()
for each packet. This simplifies both callers and nd6_output_lle()
implementation.
* Make nd6_output_lle() static and remove now-unused lle and chain
arguments.
* Rename nd6_output_flush() -> nd6_flush_holdchain() to be consistent.
* Move all pre-send transmit hooks to newly-created nd6_output_ifp().
Now nd6_output(), nd6_output_lle() and nd6_flush_holdchain() are using
it to send mbufs to if_output.
* Remove SeND hook from nd6_na_input() because it was implemented
incorrectly since the beginning (r211501):
- it tagged initial input mbuf (m) instead of m_hold
- tagging _all_ mbufs in holdchain seems to be wrong anyway.
the knowledge of mbuf layout, and in particular constants such as M_EXT,
MLEN, MHLEN, and so on, in mbuf consumers by unifying various alignment
utility functions (M_ALIGN(), MH_ALIGN(), MEXT_ALIGN() in a single
M_ALIGN() macro, implemented by a now-inlined m_align() function:
- Move m_align() from uipc_mbuf.c to mbuf.h; mark as __inline.
- Reimplement M_ALIGN(), MH_ALIGN(), and MEXT_ALIGN() using m_align().
- Update consumers around the tree to simply use M_ALIGN().
This change eliminates a number of cases where mbuf consumers must be aware
of whether or not mbufs returned by the allocator use external storage, but
also assumptions about the size of the returned mbuf. This will make it
easier to introduce changes in how we use external storage, as well as
features such as variable-size mbufs.
Differential Revision: https://reviews.freebsd.org/D1436
Reviewed by: glebius, trasz, gnn, bz
Sponsored by: EMC / Isilon Storage Division
* Make most of lltable_* methods 'normal' functions instead of inline
* Add lltable_get_<af|ifp>() functions to access given lltable fields
* Temporarily resurrect nd6_lookup() function
rather than passing them in by value.
The eventual aim is to do incremental hash construction rather than
all of the memcpy()'ing into a contiguous buffer for the hash
function, which does show up as taking quite a bit of CPU during
profiling.
Tested:
* a variety of laptops/desktop setups I have, with v6 connectivity
Differential Revision: D1404
Reviewed by: bz, rpaulo
ipsec6_in_reject() does the same things, also it counts policy violation
errors.
Do IPSEC check in the ip6_forward() after addresses checks.
Also use ip6_ipsec_fwd() to make code similar to IPv4 implementation.
Obtained from: Yandex LLC
Sponsored by: Yandex LLC
ipsec_getpolicybyaddr()
ipsec4_checkpolicy()
ip_ipsec_output()
ip6_ipsec_output()
The only flag used here was IP_FORWARDING.
Obtained from: Yandex LLC
Sponsored by: Yandex LLC
Remove check for presence PACKET_TAG_IPSEC_IN_DONE mbuf tag from
ip_ipsec_fwd(). PACKET_TAG_IPSEC_IN_DONE tag means that packet is
already handled by IPSEC code. This means that before IPSEC processing
it was destined to our address and security policy was checked in
the ip_ipsec_input(). After IPSEC processing packet has new IP
addresses and destination address isn't our own. So, anyway we can't
check security policy from the mbuf tag, because it corresponds
to different addresses.
We should check security policy that corresponds to packet
attributes in both cases - when it has a mbuf tag and when it has not.
Obtained from: Yandex LLC
Sponsored by: Yandex LLC
security policy. The changed block of code in ip*_ipsec_input() is
called when packet has ESP/AH header. Presence of
PACKET_TAG_IPSEC_IN_DONE mbuf tag in the same time means that
packet was already handled by IPSEC and reinjected in the netisr,
and it has another ESP/AH headers (encrypted twice?).
Since it was already processed by IPSEC code, the AH/ESP headers
was already stripped (and probably outer IP header was stripped too)
and security policy from the tdb_ident was applied to those headers.
It is incorrect to apply this security policy to current headers.
Also make ip_ipsec_input() prototype similar to ip6_ipsec_input().
Obtained from: Yandex LLC
Sponsored by: Yandex LLC
PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED mbuf tags. They aren't used in FreeBSD.
Instead check presence of PACKET_TAG_IPSEC_OUT_DONE mbuf tag. If it
is found, bypass security policy lookup as described in the comment.
PACKET_TAG_IPSEC_OUT_DONE tag added to mbuf when IPSEC code finishes
ESP/AH processing. Since it was already finished, this means the security
policy placed in the tdb_ident was already checked. And there is no reason
to check it again here.
Obtained from: Yandex LLC
Sponsored by: Yandex LLC
use llt_fill_sa_entry() llt method to store lle address in sa.
* Eliminate L3_ADDR macro and either reference IPv4/IPv6 address
directly from lle or use newly-created llt_fill_sa_entry().
* Do not store sockaddr inside arp/ndp lle anymore.
number of races which could cause double frees or use-after-frees when
performing DAD on an address. In particular, an IPv6 address can now only be
marked as a duplicate from the DAD callout.
Differential Revision: https://reviews.freebsd.org/D1258
Reviewed by: ae, hrs
Reported by: rstone
MFC after: 1 month
and explicit calls to RTENTRY_FREE_LOCKED()
* Use lltable_prefix_free() in arp_ifscrub to be consistent with nd6.
* Rename <lltable_|llt>_delete function to _delete_addr() to note that
this function is used to external callers. Make this function maintain
its own locking.
* Use lookup/unlink/clear call chain from internal callers instead of
delete_addr.
* Fix LLE_DELETED flag handling
cleanup including unlinking/freeing
* Relax locking in lltable_prefix_free_af/lltable_free
* Do not pass @llt to lle free callback: it is always NULL now.
* Unify arptimer/nd6_llinfo_timer: explicitly unlock lle avoiding
unlock/lock sequinces
* Do not pass unlocked lle to nd6_ns_output(): add nd6_llinfo_get_holdsrc()
to retrieve preferred source address from lle hold queue and pass it
instead of lle.
* Finally, make nd6_create() create and return unlocked lle
* Separate defrtr handling code from nd6_free():
use nd6_check_del_defrtr() to check if we need to keep entry instead of
performing GC,
use nd6_check_recalc_defrtr() to perform actual recalc on lle removal.
* Move isRouter handling from nd6_cache_lladdr() to separate
nd6_check_router()
* Add initial code to maintain lle runtime flags in sync.
