193 Commits

Author SHA1 Message Date
melifaro
95c680b9a3 Do not return unlocked/unreferenced lle in arpresolve/nd6_storelladdr -
return lle flags IFF needed.
Do not pass rte to arpresolve - pass is_gateway flag instead.
2014-11-27 23:06:25 +00:00
ae
0d350694ed Skip L2 addresses lookups for p2p interfaces.
Discussed with:	melifaro
Sponsored by:	Yandex LLC
2014-11-24 21:51:43 +00:00
glebius
f28e253225 Consistently use if_link.
Reviewed by:	ae, melifaro
2014-11-10 15:56:30 +00:00
melifaro
94efd07208 Remove unused 'struct route *' argument from nd6_output_flush(). 2014-11-09 16:20:27 +00:00
glebius
99f4ec50e8 Remove SYSCTL_VNET_* macros, and simply put CTLFLAG_VNET where needed.
Sponsored by:	Nginx, Inc.
2014-11-07 09:39:05 +00:00
melifaro
11af63037f Make checks for rt_mtu generic:
Some virtual if drivers has (ab)used ifa ifa_rtrequest hook to enforce
route MTU to be not bigger that interface MTU. While ifa_rtrequest hooking
might be an option in some situation, it is not feasible to do MTU checks
there: generic (or per-domain) routing code is perfectly capable of doing
this.

We currrently have 3 places where MTU is altered:

1) route addition.
 In this case domain overrides radix _addroute callback (in[6]_addroute)
 and all necessary checks/fixes are/can be done there.

2) route change (especially, GW change).
 In this case, there are no explicit per-domain calls, but one can
 override rte by setting ifa_rtrequest hook to domain handler
 (inet6 does this).

3) ifconfig ifaceX mtu YYYY
 In this case, we have no callbacks, but ip[6]_output performes runtime
 checks and decreases rt_mtu if necessary.

Generally, the goals are to be able to handle all MTU changes in
 control plane, not in runtime part, and properly deal with increased
 interface MTU.

This commit changes the following:
* removes hooks setting MTU from drivers side
* adds proper per-doman MTU checks for case 1)
* adds generic MTU check for case 2)

* The latter is done by using new dom_ifmtu callback since
 if_mtu denotes L3 interface MTU, e.g. maximum trasmitted _packet_ size.
 However, IPv6 mtu might be different from if_mtu one (e.g. default 1280)
 for some cases, so we need an abstract way to know maximum MTU size
 for given interface and domain.
* moves rt_setmetrics() before MTU/ifa_rtrequest hooks since it copies
  user-supplied data which must be checked.
* removes RT_LOCK_ASSERT() from other ifa_rtrequest hooks to be able to
  use this functions on new non-inserted rte.

More changes will follow soon.

MFC after:	1 month
Sponsored by:	Yandex LLC
2014-11-06 13:13:09 +00:00
asomers
081aa8a15c Revisions 264905 and 266860 added a "int fib" argument to ifa_ifwithnet and
ifa_ifwithdstaddr. For the sake of backwards compatibility, the new
arguments were added to new functions named ifa_ifwithnet_fib and
ifa_ifwithdstaddr_fib, while the old functions became wrappers around the
new ones that passed RT_ALL_FIBS for the fib argument. However, the
backwards compatibility is not desired for FreeBSD 11, because there are
numerous other incompatible changes to the ifnet(9) API. We therefore
decided to remove it from head but leave it in place for stable/9 and
stable/10. In addition, this commit adds the fib argument to
ifa_ifwithbroadaddr for consistency's sake.

sys/sys/param.h
	Increment __FreeBSD_version

sys/net/if.c
sys/net/if_var.h
sys/net/route.c
	Add fibnum argument to ifa_ifwithbroadaddr, and remove the _fib
	versions of ifa_ifwithdstaddr, ifa_ifwithnet, and ifa_ifwithroute.

sys/net/route.c
sys/net/rtsock.c
sys/netinet/in_pcb.c
sys/netinet/ip_options.c
sys/netinet/ip_output.c
sys/netinet6/nd6.c
	Fixup calls of modified functions.

share/man/man9/ifnet.9
	Document changed API.

CR:		https://reviews.freebsd.org/D458
MFC after:	Never
Sponsored by:	Spectra Logic
2014-09-11 20:21:03 +00:00
ae
d3b7992ac3 Fix condition.
Sponsored by:	Yandex LLC
2014-07-11 06:34:15 +00:00
ume
f4b1b7cb52 Make nd6_gctimer tunable.
MFC after:	1 week
2014-06-23 16:27:29 +00:00
asomers
7ca8bf0f2c Fix unintended KBI change from r264905. Add _fib versions of
ifa_ifwithnet() and ifa_ifwithdstaddr()  The legacy functions will call the
_fib() versions with RT_ALL_FIBS, preserving legacy behavior.

sys/net/if_var.h
sys/net/if.c
	Add legacy-compatible functions as described above.  Ensure legacy
	behavior when RT_ALL_FIBS is passed as fibnum.

sys/netinet/in_pcb.c
sys/netinet/ip_output.c
sys/netinet/ip_options.c
sys/net/route.c
sys/net/rtsock.c
sys/netinet6/nd6.c
	Call with _fib() functions if we must use a specific fib, or the
	legacy functions otherwise.

tests/sys/netinet/fibs_test.sh
tests/sys/netinet/udp_dontroute.c
	Improve the udp_dontroute test.  The bug that this test exercises is
	that ifa_ifwithnet() will return the wrong address, if multiple
	interfaces have addresses on the same subnet but with different
	fibs.  The previous version of the test only considered one possible
	failure mode: that ifa_ifwithnet_fib() might fail to find any
	suitable address at all.  The new version also checks whether
	ifa_ifwithnet_fib() finds the correct address by checking where the
	ARP request goes.

Reported by:	bz, hrs
Reviewed by:	hrs
MFC after:	1 week
X-MFC-with:	264905
Sponsored by:	Spectra Logic
2014-05-29 21:03:49 +00:00
asomers
f8a34b6f49 Fix subnet and default routes on different FIBs on the same subnet.
These two bugs are closely related.  The root cause is that ifa_ifwithnet
does not consider FIBs when searching for an interface address.

sys/net/if_var.h
sys/net/if.c
	Add a fib argument to ifa_ifwithnet and ifa_ifwithdstadddr.  Those
	functions will only return an address whose interface fib equals the
	argument.

sys/net/route.c
	Update calls to ifa_ifwithnet and ifa_ifwithdstaddr with fib
	arguments.

sys/netinet/in.c
	Update in_addprefix to consider the interface fib when adding
	prefixes.  This will prevent it from not adding a subnet route when
	one already exists on a different fib.

sys/net/rtsock.c
sys/netinet/in_pcb.c
sys/netinet/ip_output.c
sys/netinet/ip_options.c
sys/netinet6/nd6.c
	Add RT_DEFAULT_FIB arguments to ifa_ifwithdstaddr and ifa_ifwithnet.
	In some cases it there wasn't a clear specific fib number to use.
	In others, I was unable to test those functions so I chose
	RT_DEFAULT_FIB to minimize divergence from current behavior.  I will
	fix some of the latter changes along with PR kern/187553.

tests/sys/netinet/fibs_test.sh
tests/sys/netinet/udp_dontroute.c
tests/sys/netinet/Makefile
	Revert r263738.  The udp_dontroute test was right all along.
	However, bugs kern/187550 and kern/187553 cancelled each other out
	when it came to this test.  Because of kern/187553, ifa_ifwithnet
	searched the default fib instead of the requested one, but because
	of kern/187550, there was an applicable subnet route on the default
	fib.  The new test added in r263738 doesn't work right, however.  I
	can verify with dtrace that ifa_ifwithnet returned the wrong address
	before I applied this commit, but route(8) miraculously found the
	correct interface to use anyway.  I don't know how.

	Clear expected failure messages for kern/187550 and kern/187552.

PR:		kern/187550
PR:		kern/187552
Reviewed by:	melifaro
MFC after:	3 weeks
Sponsored by:	Spectra Logic
2014-04-24 23:56:56 +00:00
melifaro
dfdcfd9e83 Further simplify nd6_output_lle.
Currently we have 3 usage patterns:
1) nd6_output (most traffic flow, no lle supplied, lle RLOCK sufficient)
2) corner cases for output (no lle, STALE lle, so on). lle WLOCK needed.
3) nd* iunternal machinery (WLOCK'ed lle provided, perform packet queing).

We separate case 1 and implement it inside its only customer - nd6_output.
This leads to some code duplication (especialy SEND stuff, which should be
hooked to output in a different way), but simplifies locking and control
flow logic fir nd6_output_lle.

Reviewed by:	ae
MFC after:	3 weeks
Sponsored by:	Yandex LLC
2014-02-13 19:09:04 +00:00
melifaro
0525ade939 Simplify nd6_output_lle:
* Check ND6_IFF_IFDISABLED before acquiring any locks
* Assume m is always non-NULL
* remove 'bad' case not used anymore
* Simply if_output conditional

MFC after:	2 weeks
Sponsored by:	Yandex LLC
2014-02-10 12:52:33 +00:00
ae
3fc4af35a2 Unlock entry before retry.
Submitted by:	melifaro
MFC after:	1 week
2014-02-07 10:58:46 +00:00
ae
d86e904d3f Take exclusive lock only when lle isn't NULL. We don't need write access
to lle in most cases.

MFC after:	1 week
Sponsored by:	Yandex LLC
2014-02-02 07:28:04 +00:00
melifaro
6ee59753ec Further rework netinet6 address handling code:
* Set ia address/mask values BEFORE attaching to address lists.
Inet6 address assignment is not atomic, so the simplest way to
do this atomically is to fill in ia before attach.
* Validate irfa->ia_addr field before use (we permit ANY sockaddr in old code).
* Do some renamings:
  in6_ifinit -> in6_notify_ifa (interaction with other subsystems is here)
  in6_setup_ifa -> in6_broadcast_ifa (LLE/Multicast/DaD code)
  in6_ifaddloop -> nd6_add_ifa_lle
  in6_ifremloop -> nd6_rem_ifa_lle
* Split working with LLE and route announce code for last two.
Add temporary in6_newaddrmsg() function to mimic current rtsock behaviour.
* Call device SIOCSIFADDR handler IFF we're adding first address.
In IPv4 we have to call it on every address change since ARP record
is installed by arp_ifinit() which is called by given handler.
IPv6 stack, on the opposite is responsible to call nd6_add_ifa_lle() so
there is no reason to call SIOCSIFADDR often.
2014-01-19 16:07:27 +00:00
ae
4b9dcf4e75 lla_lookup() does modification only when LLE_CREATE is specified.
Thus we can use IF_AFDATA_RLOCK() instead of IF_AFDATA_LOCK() when doing
lla_lookup() without LLE_CREATE flag.

Reviewed by:	glebius, adrian
MFC after:	1 week
Sponsored by:	Yandex LLC
2014-01-02 08:40:37 +00:00
adrian
64782f1b07 Use an RLOCK here instead of an RWLOCK - matching all the other calls
to lla_lookup().

This drastically reduces the very high lock contention when doing parallel
TCP throughput tests (> 1024 sockets) with IPv6.

Tested:

* parallel IPv6 TCP bulk data exchange, 8192 sockets

MFC after:	1 week
Sponsored by:	Netflix, Inc.
2014-01-01 00:56:26 +00:00
attilio
7ee4e910ce - For kernel compiled only with KDTRACE_HOOKS and not any lock debugging
option, unbreak the lock tracing release semantic by embedding
  calls to LOCKSTAT_PROFILE_RELEASE_LOCK() direclty in the inlined
  version of the releasing functions for mutex, rwlock and sxlock.
  Failing to do so skips the lockstat_probe_func invokation for
  unlocking.
- As part of the LOCKSTAT support is inlined in mutex operation, for
  kernel compiled without lock debugging options, potentially every
  consumer must be compiled including opt_kdtrace.h.
  Fix this by moving KDTRACE_HOOKS into opt_global.h and remove the
  dependency by opt_kdtrace.h for all files, as now only KDTRACE_FRAMES
  is linked there and it is only used as a compile-time stub [0].

[0] immediately shows some new bug as DTRACE-derived support for debug
in sfxge is broken and it was never really tested.  As it was not
including correctly opt_kdtrace.h before it was never enabled so it
was kept broken for a while.  Fix this by using a protection stub,
leaving sfxge driver authors the responsibility for fixing it
appropriately [1].

Sponsored by:	EMC / Isilon storage division
Discussed with:	rstone
[0] Reported by:	rstone
[1] Discussed with:	philip
2013-11-25 07:38:45 +00:00
glebius
ff6e113f1b The r48589 promised to remove implicit inclusion of if_var.h soon. Prepare
to this event, adding if_var.h to files that do need it. Also, include
all includes that now are included due to implicit pollution via if_var.h

Sponsored by:	Netflix
Sponsored by:	Nginx, Inc.
2013-10-26 17:58:36 +00:00
markj
29e4661920 Implement the ip, tcp, and udp DTrace providers. The probe definitions use
dynamic translation so that their arguments match the definitions for
these providers in Solaris and illumos. Thus, existing scripts for these
providers should work unmodified on FreeBSD.

Tested by:	gnn, hiren
MFC after:	1 month
2013-08-25 21:54:41 +00:00
andre
7cc6cc696c Add m_clrprotoflags() to clear protocol specific mbuf flags at up and
downwards layer crossings.

Consistently use it within IP, IPv6 and ethernet protocols.

Discussed with:	trociny, glebius
2013-08-19 13:27:32 +00:00
hrs
9b92a60da0 Return 0 in nbi->expire when la_expire == 0. Conversion from time_uptime to
time_second should not be performed in this case.
2013-08-17 07:14:45 +00:00
hrs
c5a14d7164 Fix incompatibility in ICMPV6CTL_ND6_PRLIST sysctl, and SIOCGPRLST_IN6,
SIOCGDRLST_IN6, and SIOCGNBRINFO_IN6 ioctl.  These userland interfaces
treat expiration times in time_second, not time_uptime.
2013-08-06 17:10:52 +00:00
hrs
13c1bcf2c1 - Use time_uptime instead of time_second in data structures for
PF_INET6 in kernel.  This fixes various malfunction when the wall time
  clock is changed.  Bump __FreeBSD_version to 1000041.

- Use clock_gettime(CLOCK_MONOTONIC_FAST) in userland utilities.

MFC after:	1 month
2013-08-05 20:13:02 +00:00
hrs
64e5ea0653 Allocate in6_ifextra (ifp->if_afdata[AF_INET6]) only for IPv6-capable
interfaces.  This eliminates unnecessary IPv6 processing for non-IPv6
interfaces.

MFC after:	3 days
2013-07-31 16:24:49 +00:00
hrs
50e0add9e4 - Allow ND6_IFF_AUTO_LINKLOCAL for IFT_BRIDGE. An interface with IFT_BRIDGE
is initialized with !ND6_IFF_AUTO_LINKLOCAL && !ND6_IFF_ACCEPT_RTADV
  regardless of net.inet6.ip6.accept_rtadv and net.inet6.ip6.auto_linklocal.
  To configure an autoconfigured link-local address (RFC 4862), the
  following rc.conf(5) configuration can be used:

   ifconfig_bridge0_ipv6="inet6 auto_linklocal"

- if_bridge(4) now removes IPv6 addresses on a member interface to be
  added when the parent interface or one of the existing member
  interfaces has an IPv6 address.  if_bridge(4) merges each link-local
  scope zone which the member interfaces form respectively, so it causes
  address scope violation.  Removal of the IPv6 addresses prevents it.

- if_lagg(4) now removes IPv6 addresses on a member interfaces
  unconditionally.

- Set reasonable flags to non-IPv6-capable interfaces. [*]

Submitted by:	rpaulo [*]
MFC after:	1 week
2013-07-02 16:58:15 +00:00
glebius
b4bc270e8f Add const qualifier to the dst parameter of the ifnet if_output method. 2013-04-26 12:50:32 +00:00
kevlo
0cbbbb7d30 Clean up some unused leftover code.
Pointed out by:	ae
2013-03-22 01:45:54 +00:00
np
e7cfe70efd Generate lle_event in the IPv6 neighbor discovery code too.
Reviewed by:	bz@
2013-01-26 00:05:22 +00:00
np
09b8766144 Avoid NULL dereference in nd6_storelladdr when no mbuf is provided. It
is called this way from a couple of places in the OFED code.  (toecore
calls it too but that's going to change shortly).

Reviewed by:	bz@
2013-01-25 23:11:13 +00:00
glebius
8137816adb Fix problem in r238990. The LLE_LINKED flag should be tested prior to
entering llentry_free(), and in case if we lose the race, we should simply
perform LLE_FREE_LOCKED(). Otherwise, if the race is lost by the thread
performing arptimer(), it will remove two references from the lle instead
of one.

Reported by:	Ian FREISLICH <ianf clue.co.za>
2012-12-13 11:11:15 +00:00
ae
4e1bc5063b Reduce the overhead of locking, use IF_AFDATA_RLOCK() when we are doing
simple lookups.

Sponsored by:	Yandex LLC
MFC after:	1 week
2012-11-16 12:12:02 +00:00
delphij
3948ce713c Remove __P.
Submitted by:	kevlo
Reviewed by:	md5(1)
MFC after:	2 months
2012-10-22 21:49:56 +00:00
andre
34a9a386cb Mechanically remove the last stray remains of spl* calls from net*/*.
They have been Noop's for a long time now.
2012-10-18 13:57:24 +00:00
bz
95907ed567 MFp4 bz_ipv6_fast:
Use M_ZERO with malloc rather than calling bzero() ourselves.

  Change if () panic() checks to KASSERT()s as they are only
  catching invariants in code flow but not dependent on network
  input/output.

  Move initial assigments indirecting pointers after the lock
  has been aquired.

  Passing layer boundries, reset M_PROTOFLAGS.

  Remove a NULL assignment before free.

  Sponsored by:	The FreeBSD Foundation
  Sponsored by:	iXsystems

Reviewed by:	gnn (as part of the whole)
MFC After:	3 days
2012-05-25 09:27:16 +00:00
marius
b8d578077a Rewrite nd6_sysctl_{d,p}rlist() to avoid misaligned accesses to char arrays
casted to structs by getting rid of these buffers entirely. In r169832, it
was tried to paper over this issue by 32-bit aligning the buffers. Depending
on compiler optimizations that still was insufficient for 64-bit architectures
with strong alignment requirements though.
While at it, add comments regarding the total lack of locking in this area.

Tested by:	bz
Reviewed by:	bz (slightly earlier version), yongari (earlier version)
MFC after:	1 week
2012-05-20 05:12:31 +00:00
bz
b70c7f1db8 In nd6_options() ignore the RFC 6106 options completely rather than printing
them if nd6_debug is enabled as unknown.  Leave a comment about the RFC4191
option as I am undecided so far.

Discussed with:	hrs
MFC after:	3 days
2012-03-04 18:51:45 +00:00
hrs
ae62f802c7 Remove a redundant check. 2012-03-02 07:22:04 +00:00
bz
dcdb23291f Merge multi-FIB IPv6 support from projects/multi-fibv6/head/:
Extend the so far IPv4-only support for multiple routing tables (FIBs)
introduced in r178888 to IPv6 providing feature parity.

This includes an extended rtalloc(9) KPI for IPv6, the necessary
adjustments to the network stack, and user land support as in netstat.

Sponsored by:	Cisco Systems, Inc.
Reviewed by:	melifaro (basically)
MFC after:	10 days
2012-02-17 02:39:58 +00:00
pluknet
cf0bd26fe1 Remove unused variable.
The actual ia6->ia6_lifetime access is hidden in
IFA6_IS_INVALID/IFA6_IS_DEPRECATED macros since a long time ago
(see netinet6/nd6.c, r1.104 of KAME for the reference).

MFC after:	3 days
2012-01-25 08:53:42 +00:00
jhb
4ef366671a Convert all users of IF_ADDR_LOCK to use new locking macros that specify
either a read lock or write lock.

Reviewed by:	bz
MFC after:	2 weeks
2012-01-05 19:00:36 +00:00
jhb
7a0151720c Use queue(3) macros instead of home-rolled versions in several places in
the INET6 code.  This includes retiring the 'ndpr_next' and 'pfr_next'
macros.

Submitted by:	pluknet (earlier version)
Reviewed by:	pluknet
2011-12-29 18:25:18 +00:00
glebius
27a36f6ac8 A major overhaul of the CARP implementation. The ip_carp.c was started
from scratch, copying needed functionality from the old implemenation
on demand, with a thorough review of all code. The main change is that
interface layer has been removed from the CARP. Now redundant addresses
are configured exactly on the interfaces, they run on.

The CARP configuration itself is, as before, configured and read via
SIOCSVH/SIOCGVH ioctls. A new prefix created with SIOCAIFADDR or
SIOCAIFADDR_IN6 may now be configured to a particular virtual host id,
which makes the prefix redundant.

ifconfig(8) semantics has been changed too: now one doesn't need
to clone carpXX interface, he/she should directly configure a vhid
on a Ethernet interface.

To supply vhid data from the kernel to an application the getifaddrs(8)
function had been changed to pass ifam_data with each address. [1]

The new implementation definitely closes all PRs related to carp(4)
being an interface, and may close several others. It also allows
to run a single redundant IP per interface.

Big thanks to Bjoern Zeeb for his help with inet6 part of patch, for
idea on using ifam_data and for several rounds of reviewing!

PR:		kern/117000, kern/126945, kern/126714, kern/120130, kern/117448
Reviewed by:	bz
Submitted by:	bz [1]
2011-12-16 12:16:56 +00:00
qingli
3b996bbc11 A default route learned from the RAs could be deleted manually
after its installation. This removal may be accidental and can
prevent the default route from being installed in the future if
the associated default router has the best preference. The cause
is the lack of status update in the default router on the state
of its route installation in the kernel FIB. This patch fixes
the described problem.

Reviewed by:	hrs, discussed with hrs
MFC after:	5 days
2011-11-11 23:22:38 +00:00
hrs
145ad1ad8c Fix a problem that an interface unexpectedly becomes IFF_UP by
just doing "ifconfing inet6 -ifdisabled" when the interface has
ND6_IFF_AUTO_LINKLOCAL flag and no link-local address.
2011-10-16 19:46:52 +00:00
bz
772dd0b1c3 Fix an obvious bug from r186196 shadowing a variable, not correctly
appending the new mbuf to the chain reference but possibly causing an mbuf
nextpkt loop leading to a memory used after handoff (or having been freed)
and leaking an mbuf here.

Reviewed by:	rwatson, brooks
MFC after:	3 days
2011-09-30 18:20:16 +00:00
hrs
0ae2d5f6c6 Do not activate automatic LL addr configuration when 0/1->1 transition of
ND6_IFF_IFDISABLED flag.
2011-06-06 04:12:57 +00:00
hrs
acbda2ccc1 - Make the code more proactively clear an ND6_IFF_IFDISABLED flag when
an explicit action for INET6 configuration happens.  The changes are:

  1. When an ND6 flag is changed via SIOCSIFINFO_FLAGS ioctl,
     setting ND6_IFF_ACCEPT_RTADV and/or ND6_IFF_AUTO_LINKLOCAL now triggers
     an attempt to clear the ND6_IFF_IFDISABLED flag.

  2. When an AF_INET6 address is added successfully to an interface and
     it is marked as ND6_IFF_IFDISABLED, an attempt to clear the
     ND6_IFF_IFDISABLED happens.

  This simplifies ND6_IFF_IFDISABLED flag manipulation by users via ifconfig(8);
  in most cases manual configuration is no longer needed.

- When ND6_IFF_AUTO_LINKLOCAL is set and no link-local address is assigned to
  an interface, SIOCSIFINFO_FLAGS ioctl now calls in6_ifattach() to configure
  a link-local address.

  This change ensures link-local address configuration when "ifconfig IF inet6"
  command is invoked.  For example, "ifconfig IF inet6 auto_linklocal" now
  always try to configure an LL addr even if ND6_IFF_AUTO_LINKLOCAL is already
  set to 1 (i.e. down/up cycle is no longer needed).

Reviewed by:	bz
2011-06-06 02:37:38 +00:00
hrs
4c2206b625 - Accept Router Advertisement messages even when net.inet6.ip6.forwarding=1.
- A new per-interface knob IFF_ND6_NO_RADR and sysctl IPV6CTL_NO_RADR.
  This controls if accepting a route in an RA message as the default route.
  The default value for each interface can be set by net.inet6.ip6.no_radr.
  The system wide default value is 0.

- A new sysctl: net.inet6.ip6.norbit_raif.  This controls if setting R-bit in
  NA on RA accepting interfaces.  The default is 0 (R-bit is set based on
  net.inet6.ip6.forwarding).

Background:

 IPv6 host/router model suggests a router sends an RA and a host accepts it for
 router discovery.  Because of that, KAME implementation does not allow
 accepting RAs when net.inet6.ip6.forwarding=1.  Accepting RAs on a router can
 make the routing table confused since it can change the default router
 unintentionally.

 However, in practice there are cases where we cannot distinguish a host from
 a router clearly.  For example, a customer edge router often works as a host
 against the ISP, and as a router against the LAN at the same time.  Another
 example is a complex network configurations like an L2TP tunnel for IPv6
 connection to Internet over an Ethernet link with another native IPv6 subnet.
 In this case, the physical interface for the native IPv6 subnet works as a
 host, and the pseudo-interface for L2TP works as the default IP forwarding
 route.

Problem:

 Disabling processing RA messages when net.inet6.ip6.forwarding=1 and
 accepting them when net.inet6.ip6.forward=0 cause the following practical
 issues:

 - A router cannot perform SLAAC.  It becomes a problem if a box has
   multiple interfaces and you want to use SLAAC on some of them, for
   example.  A customer edge router for IPv6 Internet access service
   using an IPv6-over-IPv6 tunnel sometimes needs SLAAC on the
   physical interface for administration purpose; updating firmware
   and so on (link-local addresses can be used there, but GUAs by
   SLAAC are often used for scalability).

 - When a host has multiple IPv6 interfaces and it receives multiple RAs on
   them, controlling the default route is difficult.  Router preferences
   defined in RFC 4191 works only when the routers on the links are
   under your control.

Details of Implementation Changes:

 Router Advertisement messages will be accepted even when
 net.inet6.ip6.forwarding=1.  More precisely, the conditions are as
 follow:

 (ACCEPT_RTADV && !NO_RADR && !ip6.forwarding)
	=> Normal RA processing on that interface. (as IPv6 host)

 (ACCEPT_RTADV && (NO_RADR || ip6.forwarding))
	=> Accept RA but add the router to the defroute list with
	   rtlifetime=0 unconditionally.  This effectively prevents
	   from setting the received router address as the box's
	   default route.

 (!ACCEPT_RTADV)
	=> No RA processing on that interface.

 ACCEPT_RTADV and NO_RADR are per-interface knob.  In short, all interface
 are classified as "RA-accepting" or not.  An RA-accepting interface always
 processes RA messages regardless of ip6.forwarding.  The difference caused by
 NO_RADR or ip6.forwarding is whether the RA source address is considered as
 the default router or not.

 R-bit in NA on the RA accepting interfaces is set based on
 net.inet6.ip6.forwarding.  While RFC 6204 W-1 rule (for CPE case) suggests
 a router should disable the R-bit completely even when the box has
 net.inet6.ip6.forwarding=1, I believe there is no technical reason with
 doing so.  This behavior can be set by a new sysctl net.inet6.ip6.norbit_raif
 (the default is 0).

Usage:

 # ifconfig fxp0 inet6 accept_rtadv
	=> accept RA on fxp0
 # ifconfig fxp0 inet6 accept_rtadv no_radr
	=> accept RA on fxp0 but ignore default route information in it.
 # sysctl net.inet6.ip6.norbit_no_radr=1
	=> R-bit in NAs on RA accepting interfaces will always be set to 0.
2011-06-06 02:14:23 +00:00