After the afdata read lock was converted to epoch(9), readers could
observe a linked LLE and block on the LLE while a thread was
unlinking the LLE. The writer would then release the lock and schedule
the LLE for deferred free, allowing readers to continue and potentially
schedule the LLE timer. By the point the timer fires, the structure is
freed, typically resulting in a crash in the callout subsystem.
Fix the problem by modifying the lookup path to check for the LLE_LINKED
flag upon acquiring the LLE lock. If it's not set, the lookup fails.
PR: 234296
Reviewed by: bz
Tested by: sbruno, Victor <chernov_victor@list.ru>,
Mike Andrews <mandrews@bit0.com>
MFC after: 3 days
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D18906
- Remove macros that covertly create epoch_tracker on thread stack. Such
macros a quite unsafe, e.g. will produce a buggy code if same macro is
used in embedded scopes. Explicitly declare epoch_tracker always.
- Unmask interface list IFNET_RLOCK_NOSLEEP(), interface address list
IF_ADDR_RLOCK() and interface AF specific data IF_AFDATA_RLOCK() read
locking macros to what they actually are - the net_epoch.
Keeping them as is is very misleading. They all are named FOO_RLOCK(),
while they no longer have lock semantics. Now they allow recursion and
what's more important they now no longer guarantee protection against
their companion WLOCK macros.
Note: INP_HASH_RLOCK() has same problems, but not touched by this commit.
This is non functional mechanical change. The only functionally changed
functions are ni6_addrs() and ni6_store_addrs(), where we no longer enter
epoch recursively.
Discussed with: jtl, gallatin
handler receives the type of event IFADDR_EVENT_ADD/IFADDR_EVENT_DEL,
and the pointer to ifaddr. Also ifaddr_event now is implemented using
ifaddr_event_ext handler.
MFC after: 3 weeks
Sponsored by: Yandex LLC
Differential Revision: https://reviews.freebsd.org/D17100
This deduplicates the code a bit, and also implicitly adds missing
callout_stop() to in[6]_lltable_delete_entry() functions.
PR: 209682, 225927
Submitted by: hselasky (previous version)
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D4605
to sleep on commands to the NIC when updating multicast filters. More generally this permitted
driver's to use an sx as a softc lock. Unfortunately this change introduced a race whereby a
a multicast update would still be queued for deletion when ifconfig deleted the interface
thus calling down in to _purgemaddrs and synchronously deleting _all_ of the multicast addresses
on the interface.
Synchronously remove all external references to a multicast address before enqueueing for delete.
Reported by: lwhsu
Approved by: sbruno
Multicast incorrectly calls in to drivers with a mutex held causing drivers
to have to go through all manner of contortions to use a non sleepable lock.
Serialize multicast updates instead.
Submitted by: mmacy <mmacy@mattmacy.io>
Reviewed by: shurd, sbruno
Sponsored by: Limelight Networks
Differential Revision: https://reviews.freebsd.org/D14969
Current arp/nd code relies on the feedback from the datapath indicating
that the entry is still used. This mechanism is incorporated into the
arpresolve()/nd6_resolve() routines. After the inpcb route cache
introduction, the packet path for the locally-originated packets changed,
passing cached lle pointer to the ether_output() directly. This resulted
in the arp/ndp entry expire each time exactly after the configured max_age
interval. During the small window between the ARP/NDP request and reply
from the router, most of the packets got lost.
Fix this behaviour by plugging datapath notification code to the packet
path used by route cache. Unify the notification code by using single
inlined function with the per-AF callbacks.
Reported by: sthaug at nethelp.no
Reviewed by: ae
MFC after: 2 weeks
Mainly focus on files that use BSD 3-Clause license.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
A long long time ago the register keyword told the compiler to store
the corresponding variable in a CPU register, but it is not relevant
for any compiler used in the FreeBSD world today.
ANSIfy related prototypes while here.
Reviewed by: cem, jhb
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D10193
Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.
Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96
inet_ntoa() cannot be used safely in a multithreaded environment
because it uses a static local buffer. Instead, use inet_ntoa_r()
with a buffer on the caller's stack.
Suggested by: glebius, emaste
Reviewed by: gnn
MFC after: 2 weeks
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D9625
(intentionally) deleted first and then completely added again (so all the
events, announces and hooks are given a chance to run).
This cause an issue with CARP where the existing CARP data structure is
removed together with the last address for a given VHID, which will cause
a subsequent fail when the address is later re-added.
This change fixes this issue by adding a new flag to keep the CARP data
structure when an address is not being removed.
There was an additional issue with IPv6 CARP addresses, where the CARP data
structure would never be removed after a change and lead to VHIDs which
cannot be destroyed.
Reviewed by: glebius
Obtained from: pfSense
MFC after: 2 weeks
Sponsored by: Rubicon Communications, LLC (Netgate)
A single gratuitous ARP (GARP) is always transmitted when an IPv4
address is added to an interface, and that is usually sufficient.
However, in some circumstances, such as when a shared address is
passed between cluster nodes, this single GARP may occasionally be
dropped or lost. This can lead to neighbors on the network link
working with a stale ARP cache and sending packets destined for
that address to the node that previously owned the address, which
may not respond.
To avoid this situation, GARP retransmissions can be enabled by setting
the net.link.ether.inet.garp_rexmit_count sysctl to a value greater
than zero. The setting represents the maximum number of retransmissions.
The interval between retransmissions is calculated using an exponential
backoff algorithm, doubling each time, so the retransmission intervals
are: {1, 2, 4, 8, 16, ...} (seconds).
Due to the exponential backoff algorithm used for the interval
between GARP retransmissions, the maximum number of retransmissions
is limited to 16 for sanity. This limit corresponds to a maximum
interval between retransmissions of 2^16 seconds ~= 18 hours.
Increasing this limit is possible, but sending out GARPs spaced
days apart would be of little use.
Submitted by: David A. Bright <david.a.bright@dell.com>
MFC after: 1 month
Relnotes: yes
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D7695
in_broadcast() was iterating over the ifnet address list without
first taking an IF_ADDR_RLOCK. This could cause a panic if a
concurrent operation modified the list.
Reviewed by: bz
MFC after: 2 months
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D7227
For almost every packet that is transmitted through ip_output(),
a call to in_broadcast() was made to decide if the destination
IP was a broadcast address. in_broadcast() iterates over the
ifnet's address to find a source IP matching the subnet of the
destination IP, and then checks if the IP is a broadcast in that
subnet.
This is completely redundant as we have already performed the
route lookup, so the source IP is already known. Just use that
address to directly check whether the destination IP is a
broadcast address or not.
MFC after: 2 months
Sponsored By: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D7266
than removing the network interfaces first. This change is rather larger
and convoluted as the ordering requirements cannot be separated.
Move the pfil(9) framework to SI_SUB_PROTO_PFIL, move Firewalls and
related modules to their own SI_SUB_PROTO_FIREWALL.
Move initialization of "physical" interfaces to SI_SUB_DRIVERS,
move virtual (cloned) interfaces to SI_SUB_PSEUDO.
Move Multicast to SI_SUB_PROTO_MC.
Re-work parts of multicast initialisation and teardown, not taking the
huge amount of memory into account if used as a module yet.
For interface teardown we try to do as many of them as we can on
SI_SUB_INIT_IF, but for some this makes no sense, e.g., when tunnelling
over a higher layer protocol such as IP. In that case the interface
has to go along (or before) the higher layer protocol is shutdown.
Kernel hhooks need to go last on teardown as they may be used at various
higher layers and we cannot remove them before we cleaned up the higher
layers.
For interface teardown there are multiple paths:
(a) a cloned interface is destroyed (inside a VIMAGE or in the base system),
(b) any interface is moved from a virtual network stack to a different
network stack ("vmove"), or (c) a virtual network stack is being shut down.
All code paths go through if_detach_internal() where we, depending on the
vmove flag or the vnet state, make a decision on how much to shut down;
in case we are destroying a VNET the individual protocol layers will
cleanup their own parts thus we cannot do so again for each interface as
we end up with, e.g., double-frees, destroying locks twice or acquiring
already destroyed locks.
When calling into protocol cleanups we equally have to tell them
whether they need to detach upper layer protocols ("ulp") or not
(e.g., in6_ifdetach()).
Provide or enahnce helper functions to do proper cleanup at a protocol
rather than at an interface level.
Approved by: re (hrs)
Obtained from: projects/vnet
Reviewed by: gnn, jhb
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D6747
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).
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
LLE structure is mostly unchanged during its lifecycle.
To be more specific, there are 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 re-send arp request 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:
1) introduce special r_skip_req field which is read lockless by fast path,
but updated under (new) req_mutex mutex. If this field is non-zero, then
fast path will acquire lock and set it back to 0.
2) introduce simple state machine: incomplete->reachable<->verify->deleted.
Before that we implicitely had incomplete->reachable->deleted state machine,
with V_arpt_keep between "reachable" and "deleted". Verification was performed
in runtime 5 seconds before V_arpt_keep expire.
This is changed to "change state to verify 5 seconds before V_arpt_keep,
set r_skip_req to non-zero value and check it every second". If the value
is zero - then send arp verification probe.
These changes do not introduce any signifficant control plane overhead:
typically lle callout timer would fire 1 time more each V_arpt_keep (1200s)
for used lles and up to arp_maxtries (5) for dead lles.
As a result, all packets towards "reachable" lle are handled by fast path without
acquiring lle read lock.
Additional "req_mutex" is needed because callout / arpresolve_slow() or eventhandler
might keep LLE lock for signifficant amount of time, which might not be feasible
for fast path locking (e.g. having rmlock as ether AFDATA or lltable own lock).
Differential Revision: https://reviews.freebsd.org/D3688
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.
down state.
Regression appeared in r287789, where the "prefix has no corresponding
installed route" case was forgotten. Additionally, lltable_delete_addr()
was called with incorrect byte order (default is network for lltable code).
While here, improve comments on given cases and byte order.
PR: 203573
Submitted by: phk
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
* prepare gateway before insertion
* use RTM_CHANGE instead of explicit find/change route
* Remove fib argument from ifa_switch_loopback_route added in r264887:
if old ifp fib differes from new one, that the caller
is doing something wrong
* Make ifa_*_loopback_route call single ifa_maintain_loopback_route().
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
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 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
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
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.
* 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
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.
