To access route attribute cache from multiple threads at once, we have
to lock the cache on writing. The route attributes data structures are
safe to read unless somebody tries to tamper with the cache itself.
This commit prevents use-after-free of routes belonging to protocols
which have been already destroyed, delaying also all the protocols'
shutdown until all of their routes have been finally propagated through
all the pipes down to the appropriate exports.
The use-after-free was somehow hypothetic yet theoretically possible in
rare conditions, when one BGP protocol authors a lot of routes and the
user deletes that protocol by reconfiguring in the same time as next hop
update is requested, causing rte_better() to be called on a
not-yet-pruned network prefix while the owner protocol has been already
freed.
In parallel execution environments, this would happen an inter-thread
use-after-free, causing possible heisenbugs or other nasty problems.
There is a simple universal IO loop, taking care of events, timers and
sockets. Primarily, one instance of a protocol should use exactly one IO
loop to do all its work, as is now done in BFD.
Contrary to previous versions, the loop is now launched and cleaned by
the nest/proto.c code, allowing for a protocol to just request its own
loop by setting the loop's lock order in config higher than the_bird.
It is not supported nor checked if any protocol changed the requested
lock order in reconfigure. No protocol should do it at all.
In some specific configurations, it was possible to send BIRD into an
infinite loop of recursive next hop resolution. This was caused by route
priority inversion.
To prevent priority inversions affecting other next hops, we simply
refuse to resolve any next hop if the best route for the matching prefix
is recursive or any other route with the same preference is recursive.
Next hop resolution doesn't change route priority, therefore it is
perfectly OK to resolve BGP next hops e.g. by an OSPF route, yet if the
same (or covering) prefix is also announced by iBGP, by retraction of
the OSPF route we would get a possible priority inversion.
* internal tables are now more standalone, having their own import and
export hooks
* route refresh/reload uses stale counter instead of stale flag,
allowing to drop walking the table at the beginning
* route modify (by BGP LLGR) is now done by a special refeed hook,
reimporting the modified routes directly without filters
Channels have now included rt_import_req and rt_export_req to hook into
the table instead of just one list node. This will (in future) allow for:
* channel import and export bound to different tables
* more efficient pipe code (dropping most of the channel code)
* conversion of 'show route' to a special kind of export
* temporary static routes from CLI
The import / export states are also updated to the new algorithms.
Routes are now allocated only when they are just to be inserted to the
table. Updating a route needs a locally allocated route structure.
Ownership of the attributes is also now not transfered from protocols to
tables and vice versa but just borrowed which should be easier to handle
in a multithreaded environment.
Pipes copy the original rte with old values, so they require rte to be
exported with stored tmpattrs. Other protocols access stored attributes
using eattr list, so they require rte to be exported with expanded
tmpattrs. This is temporary hack, we plan to remove whoe tmpattr mechanism.
Thanks to Paul Donohue for the bugreport.
In most cases of export there is no need to store back temporary
attributes to rte, as receivers (protocols) access eattr list anyway.
But pipe copies the original rte with old values, so we should store
tmpattrs also during export.
Thanks to Paul Donohue for the bugreport.
Add support for specifying a password in hexadecimal format, The result
is the same whether a password is specified as a quoted string or a
hex-encoded byte string, this just makes it more convenient to input
high-entropy byte strings as MAC keys.
The Babel MAC authentication RFC recommends implementing Blake2s as one of
the supported algorithms. In order to achieve do this, add the blake2b and
blake2s hash functions for MAC authentication. The hashing function
implementations are the reference implementations from blake2.net.
The Blake2 algorithms allow specifying an arbitrary output size, and the
Babel MAC spec says to implement Blake2s with 128-bit output. To satisfy
this, we add two different variants of each of the algorithms, one using
the default size (256 bits for Blake2s, 512 bits for Blake2b), and one
using half the default output size.
Update to BIRD coding style done by committer.
In general, events are code handling some some condition, which is
scheduled when such condition happened and executed independently from
I/O loop. Work-events are a subgroup of events that are scheduled
repeatedly until some (often significant) work is done (e.g. feeding
routes to protocol). All scheduled events are executed during each
I/O loop iteration.
Separate work-events from regular events to a separate queue and
rate limit their execution to a fixed number per I/O loop iteration.
That should prevent excess latency when many work-events are
scheduled at one time (e.g. simultaneous reload of many BGP sessions).
This is an implementation of draft-walton-bgp-hostname-capability-02.
It is implemented since quite some time for FRR and in datacenter, this
gives a nice output to avoid using IP addresses.
It is disabled by default. The hostname is retrieved from uname(2) and
can be overriden with "hostname" option. The domain name is never set
nor displayed.
Minor changes by committer.
If there are roa_check() calls in channel filters, then the channel
subscribes to ROA table notifications, which are sent when ROA tables
are updated (subject to settle time) and trigger channel reload or
refeed.
The patch add support for per-channel debug flags, currently just
'states', 'routes', and 'filters'. Flag 'states' is used for channel
state changes, remaining two for routes passed through the channel.
The per-protocol debug flags 'routes'/'filters' still enable reporting
of routes for all channels, to keep existing behavior.
The patch causes minor changes in some log messages.
When config structures are copied due to template application,
we need to reset list node structure before calling add_tail().
Thanks to Mikael Magnusson for patches.
Logging as a result of triggered receive limit in import table code
accesset rte->net, which was not filed yet.
Thanks to Pier Carlo Chiodi for the bugreport.
Merge multiple BFD option blocks in BGP configs instead of using the last
one. That is necessary for proper handling of templates when BFD options
are used both in a BGP template and in a BGP protocol derived from that
template.
BFD session options are configured per interface in BFD protocol. This
patch allows to specify them also per-request in protocols requesting
sessions (currently limited to BGP).
Put new non-best routes to the end of list instead of the second
position. Put updated routes to their old position. Position is changed
just by best route selection.
Most commands like 'show ospf neighbors' fail when protocol is not
specified and there are multiple instances of given protocol type.
This is annoying in BIRD 2, as many protocols have IPv4 and IPv6
instances. The patch changes that by showing output from all protocol
instances of appropriate type.
Note that the patch also removes terminating cli_msg() call from these
commands and moves it to the common iterating code.
There is nothing in RFCs specifying that id 0 is not allowed. Some
implementations does not support it, while some other use key id 0 by
default. We allow it but start with key id 1 by default.
Thanks to Kenth Eriksson for the bugreport.
Implement regex-like '+' operator in BGP path masks to match previous
path mask item multiple times. This is useful as ASNs may appear
multiple times in paths due to path prepending for traffic engineering
purposes.
Resolve neighbors using longest prefix match. Although interface ranges
should not generally collide, it may happen for unnumbered links.
Thanks to Kenth Eriksson for the bugreport.
The old code stored route verdicts and temporary routes directly in
rtable. The new code do not store received routes (it immediately
compares them with exported routes and resolves conflicts) and uses
internal bitmap to keep track of which routes were received and which
needs to be reinstalled.
By not putting 'invalid' temporary routes to rtable, we keep rtable
in consistent state, therefore scan no longer needs to be atomic
operation and could be splitted to multiple events.
Channel currently does not have independent pool and uses protocol pool,
which is freed when protocol changes state to down, while channel is
still in flushing. Move some some cleanup code to channel_do_flush()
so it is done before freeing of protocol pool.
Use a hierarchical bitmap in a routing table to assign ids to routes, and
then use bitmaps (indexed by route id) in channels to keep track whether
routes were exported. This avoids unreliable and inefficient re-evaluation
of filters for old routes in order to determine whether they were exported.
Continuation lines may use short form (with space instead of message
number), but this should not be done when previous line is final.
Thanks to Kenth Eriksson for the bugreport and analysis.
Underlying (IGP) route may lead to PtP link, in this case it does not
need gateway. Which is different than direct route without gateway.
When recursive (BGP) route uses PtP route, it should not use recursive
next hop as immediate next hop, while for direct routes it should.
The patch implements optional internal export table to a channel and
hooks it to BGP so it can be used as Adj-RIB-Out. When enabled, all
exported (post-filtered) routes are stored there. An export table can be
examined using e.g. 'show route export table bgp1.ipv4'.
Several BGP channel options (including 'next hop self') could be
reconfigured without session reset, with just route refeed/refresh.
The patch improves reconfiguration code to do it that way.
Protocol can have specified VRF, in such case it is restricted to a set
of ifaces associated with the VRF, otherwise it can use all interfaces.
The patch allows to specify VRF as 'default', in which case it is
restricted to a set of iface not associated with any VRF.
When 'graceful down' command is entered, protocols are shut down
with regard to graceful restart. Namely Kernel protocol does
not remove routes and BGP protocol does not send notification,
just closes the connection.
Support for dynamically spawning BGP protocols for incoming connections.
Use 'neighbor range' to specify range of valid neighbor addresses, then
incoming connections from these addresses spawn new BGP instances.
The temporary atttributes are no longer removed by ea_do_prune(), but
they are undefined by store_tmp_attrs() protocol hooks. This fixes
several bugs where temporary attributes were removed when they should
not or not removed when they should be. The flag EAF_TEMP is no longer
needed and was removed.
Update all protocol make_tmp_attrs() / store_tmp_attrs() hooks to use
helper functions and to handle unset attributes properly.
Also fix some related bugs like improper handling of empty eattr list.
Keep track of whether OSPF tmpattrs are actually defined for given route
(using flags in rte->pflags). That makes them behave more like real
eattrs so a protocol can define just a subset of them or they can be
undefined by filters.
Do not set ospf_metric2 for other than type 2 external OSPF routes and do
not set ospf_tag for non-external OSPF routes. That also fixes a bug
where internal/inter-area route propagated from one OSPF instance to
another is initiated with infinity ospf_metric2.
Thanks to Yaroslav Dronskii for the bugreport.
Route flags are mosty internal state of rtable, they are not significant
to whether a route has changed. With the old code, all routes received as
a part of enhanced route refresh are always re-announced to other peers
due to change in REF_STALE.
This is a major change of how the filters are interpreted. If everything
works how it should, it should not affect you unless you are hacking the
filters themselves.
Anyway, this change should make a huge improvement in the filter performance
as previous benchmarks showed that our major problem lies in the
recursion itself.
There are also some changes in nest and protocols, related mostly to
spreading const declarations throughout the whole BIRD and also to
refactored dynamic attribute definitions. The need of these came up
during the whole work and it is too difficult to split out these
not-so-related changes.
One of previous workarounds for phantom route avoidance breaks export
counters by expanding sending of spurious withdraws, which are send when
we are not sure whether we have advertised that routes in the past.
If not, then export counter is decreased, but it was not increased
before, so it overflows under zero.
The patch fixes that by sendung spurious withdraws, but not counting them
on export counter. That may lead to error in the other direction, but that
happens only as a race condition (i.e., in normal operation filters
return proper values about old route export state).
The earlier fix loosen conditions for not running filters on old
route when deciding about route propagation to a protocol to avoid
issues with ghost routes in some race conditions.
Unfortunately, the fix also caused back-propagation of withdraws. For
regular updates, back-propagation is prevented in import_control hooks,
but these are not called on withdraws. For them, import_control hooks
are called on old routes instead, changing (old, NULL) notification
to (NULL, NULL), which is ignored. By not calling export processing
in some cases, the withdraw is not ignored and is back-propagated.
This patch fixes that by contract conditions so the earlier fix is not
applied to back-propagated updates.
This protocol is highly experimental and nobody should use it in
production. Anyway it may help you getting some insight into what eats
so much time in filter processing.
The patch d506263d... blocked adding channel during reconfiguration,
that broke protocols which use the same functiona also during init.
This patch fixes that.
The patch implements optional internal import table to a channel and
hooks it to BGP so it can be used as Adj-RIB-In. When enabled, all
received (pre-filtered) routes are stored there and import filters can
be re-evaluated without explicit route refresh. An import table can be
examined using e.g. 'show route import table bgp1.ipv4'.
When a new channel is found during reconfiguration, do force restart
of the protocol, like with any other un-reconfigurable change.
The old behavior was that the new channel was added but remained in down
state, even if the protocol was up, so a manual protocol restart was
often necessary.
In the future this should be improved such that a reconfigurable
channel addition (e.g. direct) is accepted and channel is started,
while an un-reconfigurable addition forces protocol restart.
For local route marking purposes, local custom route attributes may be
defined. These attributes are seamlessly stripped after export filter to
every real protocol like Kernel, BGP or OSPF, they however pass through
pipes. We currently allow at most 256 custom attributes.
This should be much faster than currently used bgp communities
for marking routes.
Once upon a time, far far away, there were the old Bird developers
discussing what direction of route flow shall be called import and
export. They decided to say "import to protocol" and "export to table"
when speaking about a protocol. When speaking about a table, they
spoke about "importing to table" and "exporting to protocol".
The latter terminology was adopted in configuration, then also the
bird CLI in commit ea2ae6dd0 started to use it (in year 2009). Now
it's 2018 and the terminology is the latter. Import is from protocol to
table, export is from table to protocol. Anyway, there was still an
import_control hook which executed right before route export.
One thing is funny. There are two commits in April 1999 with just two
minutes between them. The older announces the final settlement
on config terminology, the newer uses the other definition. Let's see
their commit messages as the git-log tool shows them (the newer first):
commit 9e0e485e50
Author: Martin Mares <mj@ucw.cz>
Date: Mon Apr 5 20:17:59 1999 +0000
Added some new protocol hooks (look at the comments for better explanation):
make_tmp_attrs Convert inline attributes to ea_list
store_tmp_attrs Convert ea_list to inline attributes
import_control Pre-import decisions
commit 5056c559c4
Author: Martin Mares <mj@ucw.cz>
Date: Mon Apr 5 20:15:31 1999 +0000
Changed syntax of attaching filters to protocols to hopefully the final
version:
EXPORT <filter-spec> for outbound routes (i.e., those announced
by BIRD to the rest of the world).
IMPORT <filter-spec> for inbound routes (i.e., those imported
by BIRD from the rest of the world).
where <filter-spec> is one of:
ALL pass all routes
NONE drop all routes
FILTER <name> use named filter
FILTER { <filter> } use explicitly defined filter
For all protocols, the default is IMPORT ALL, EXPORT NONE. This includes
the kernel protocol, so that you need to add EXPORT ALL to get the previous
configuration of kernel syncer (as usually, see doc/bird.conf.example for
a bird.conf example :)).
Let's say RIP to this almost 19-years-old inconsistency. For now, if you
import a route, it is always from protocol to table. If you export a
route, it is always from table to protocol.
And they lived happily ever after.
Modify protocols to use preferred address change notification instead on
depending on hard-reset of interfaces in that case, and remove hard-reset
in that case. This avoids issue when e.g. IPv6 protocol restarts
interface when IPv4 preferred address changed (as hard-reset is
unavoidable and common for whole iface).
The patch also fixes a bug when removing last address does not send
preferred address change notification.
The new MRT protocol is responsible for periodic RIB table dumps in the
MRT format (RFC 6396). Also the existing code for BGP4MP MRT dumps is
refactored and splitted between BGP to MRT protocols, will be more
integrated into MRT in the future.
Example:
protocol mrt {
table "*";
filename "%N_%F_%T.mrt";
period 60;
}
It is partially based on the old MRT code from Pavel Tvrdik.
no more warnings
No more warnings over me
And while it is being compiled all the log is black and white
Release BIRD now and then let it flee
(use the melody of well-known Oh Freedom!)
If export filter is changed during reconfiguration and a route disappears
between reconfiguration and refeed (e.g., if the route is a static route
also removed during the reconfiguration), the route is not withdrawn.
The issue was fixed for regular channels by an earlier patch. This patch
fixes the issue for channels in RA_ACCEPTED mode (first-pass-the-filter),
used by BGP with 'secondary' option.
If export filter is changed during reconfiguration and a route disappears
between reconfiguration and refeed (e.g., if the route is a static route
also removed during the reconfiguration), the route is not withdrawn.
The patch fixes that by adding tx reconfiguration timestamp.
This is a fundamental change of an original (1999) concept of route
processing inside BIRD. During import/export, there was a temporary
ea_list created which was to be used instead of the another one inside
the route itself.
This led to some confusion, quirks, and strange filter code that handled
extended route attributes. Dropping it now.
The protocol interface has changed in an uniform way -- the
`struct ea_list *attrs` argument has been removed from store_tmp_attrs(),
import_control(), rt_notify() and get_route_info().
The bgpmask literals can include expressions. This is OK but they have
to be interpreted as soon as the code is run, not in the time the code
is used as value.
This led to strange behavior like rewriting bgpmasks when they shan't
be rewritten:
function mask_generator(int as)
{
return [= * as * =];
}
function another()
bgpmask m1;
bgpmask m2;
{
m1 = mask_generator(10);
m2 = mask_generator(20);
if (m1 == m2) {
print("strange"); # this would happen
}
}
Moreover, sending this to CLI would cause stack overflow and knock down the
whole BIRD, as soon as there is at least one route to execute the given
filter on.
show route filter bgpmask mmm; bgppath ppp; { ppp = +empty+; mmm = [= (ppp ~ mmm) =]; print(mmm); accept; }
The magic match operator (~) inside the bgpmask literal would try to
resolve mmm, which points to the same bgpmask so it would resolve
itself, call the magic match operator and vice versa.
After this patch, the bgpmask literal will get resolved as soon as it's
assigned to mmm and it also will return a type error as bool is not
convertible to ASN in BIRD.
This patch adds support for source-specific IPv6 routes to BIRD core.
This is based on Dean Luga's original patch, with the review comments
addressed. SADR support is added to network address parsing in confbase.Y
and to the kernel protocol on Linux.
Currently there is no way to mix source-specific and non-source-specific
routes (i.e., SADR tables cannot be connected to non-SADR tables).
Thanks to Toke Hoiland-Jorgensen for the original patch.
Minor changes by Ondrej Santiago Zajicek.
A filter should log messages only if executed explicitly (e.g., during
route export or route import). When a filter is executed for technical
reasons (e.g., to establish whether a route was exported before), it
should run silently.
