Netlinks is a communication protocol currently used in Linux kernel to modify,
read and subscribe for nearly all networking state. Interfaces, addresses, routes,
firewall, fibs, vnets, etc are controlled via netlink.
It is async, TLV-based protocol, providing 1-1 and 1-many communications.
The current implementation supports the subset of NETLINK_ROUTE
family. To be more specific, the following is supported:
* Dumps:
- routes
- nexthops / nexthop groups
- interfaces
- interface addresses
- neighbors (arp/ndp)
* Notifications:
- interface arrival/departure
- interface address arrival/departure
- route addition/deletion
* Modifications:
- adding/deleting routes
- adding/deleting nexthops/nexthops groups
- adding/deleting neghbors
- adding/deleting interfaces (basic support only)
* Rtsock interaction
- route events are bridged both ways
The implementation also supports the NETLINK_GENERIC family framework.
Implementation notes:
Netlink is implemented via loadable/unloadable kernel module,
not touching many kernel parts.
Each netlink socket uses dedicated taskqueue to support async operations
that can sleep, such as interface creation. All message processing is
performed within these taskqueues.
Compatibility:
Most of the Netlink data models specified above maps to FreeBSD concepts
nicely. Unmodified ip(8) binary correctly works with
interfaces, addresses, routes, nexthops and nexthop groups. Some
software such as net/bird require header-only modifications to compile
and work with FreeBSD netlink.
Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D36002
MFC after: 2 months
Routing daemons such as bird need to know if they install certain route
so they can clean it up on startup, as a form of achieving consistent
state during the crash recovery.
Currently they use combination of routing flags (RTF_PROTO1) to detect
these routes when interacting via route(4) rtsock protocol.
Netlink protocol has a special "rtm_protocol" field that is filled and
checked by the route originator. To prepare for the upcoming netlink
introduction, add ability to record origing to both nexthops and
nexthop groups via <nhop|nhgrp>_<get|set>_origin() KPI. The actual
calls will be used in the followup commits.
MFC after: 1 month
Add IF_DEBUG_LEVEL() macro to ensure all debug output preparation
is run only if the current debug level is sufficient. Consistently
use it within routing subsystem.
MFC after: 2 weeks
* add nhop_get_unlinked() used to prepare referenced but not
linked nexthop, that can later be used as a clone source.
* add nhop_check_gateway() to check for allowed address family
combinations between the rib family and neighbor family (useful
for 4o6 or direct routes)
* add nhop_set_upper_family() to allow copying IPv6 nexthops to
IPv4 rib.
* add rt_get_rnd() wrapper, returning both nexthop/group and its
weight attached to the rtentry.
* Add CHT_SLIST_FOREACH_SAFE(), allowing to delete items during
iteration.
MFC after: 2 weeks
Multiple consumers in the kernel space want to install IPv4 or IPv6
default route. Provide convenient wrapper to simplify the code
inside the customers.
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D36167
Construct the desired hexthops directly instead of using the
"translation" layer in form of filling rt_addrinfo data.
Simplify V_rt_add_addr_allfibs handling by using recently-added
rib_copy_route() to propagate the routes to the non-primary address
fibs.
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D36166
Finish 02e05b8fae:
* add gateway matcher function that can be used in rib_del_route_px()
or any rib_walk-family functions. It will be used in the upcoming
migration to the new KPI
* rename gw_fulter_func to match_gw_one() to better signal the
function purpose / semantic.
MFC after: 1 month
route_ctl.c size has grown considerably since initial introduction.
Factor out non-relevant parts:
* all rtentry logic, such as creation/destruction and accessors
goes to net/route/route_rtentry.c
* all rtable subscription logic goes to net/route/route_subscription.c
Differential Revision: https://reviews.freebsd.org/D36074
MFC after: 1 month
This change adds public KPI to work with routes using pre-created
nexthops, instead of using data from addrinfo structures. These
functions will be later used for adding/deleting kernel-originated
routes and upcoming netlink protocol.
As a part of providing this KPI, low-level route addition code has been
reworked to provide more control over route creation or change.
Specifically, a number of operation flags
(RTM_F_<CREATE|EXCL|REPLACE|APPEND>) have been added, defining the
desired behaviour the the route already exists (or not exists). This
change required some changes in the multipath addition code, resulting
in moving this code to route_ctl.c, rendering mpath_ctl.c empty.
Differential Revision: https://reviews.freebsd.org/D36073
MFC after: 1 month
This change is required for the upcoming introduction of the next
nexhop-based operations KPI, as it will create rtentry and nexthops
at different stages of route table modification.
Differential Revision: https://reviews.freebsd.org/D36072
MFC after: 2 weeks
* Use same filter func (rib_filter_f_t) for nexhtop groups to
simplify callbacks.
* simplify conditional route deletion & remove the need to pass
rt_addrinfo to the low-level deletion functions
* speedup rib_walk_del() by removing an additional per-prefix lookup
Differential Revision: https://reviews.freebsd.org/D36071
MFC after: 1 month
This and the follow-up routing-related changes target to remove or
reduce `struct rt_addrinfo` usage and use recently-landed nhop(9)
KPI instead.
Traditionally `rt_addrinfo` structure has been used to propagate all necessary
information between the protocol/rtsock and a routing layer. Many
functions inside routing subsystem uses it internally. However, using
this structure became somewhat complicated, as there are too many ways
of specifying a single state and verifying data consistency is hard.
For example, arerouting flgs consistent with mask/gateway sockaddr pointers?
Is mask really a host mask? Are sockaddr "valid" (e.g. properly zeroed, masked,
have proper length)? Are they mutable? Is the suggested interface specified
by the interface index embedded into the sockadd_dl gateway, or passed
as RTAX_IFP parameter, or directly provided by rti_ifp or it needs to
be derived from the ifa?
These (and other similar) questions have to be considered every time when
a function has `rt_addrinfo` pointer as an argument.
The new approach is to bring more control back to the protocols and
construct the desired routing objects themselves - in the end, it's the
protocol/subsystem who knows the desired outcome.
This specific diff changes the following:
* add explicit basic low-level radix operations:
add_route() (renamed from add_route_nhop())
delete_route() (factored from change_route_nhop())
change_route() (renamed from change_route_nhop)
* remove "info" parameter from change_route_conditional() as a part
of reducing rt_addrinfo usage in the internal KPIs
* add lookup_prefix_rt() wrapper for doing re-lookups after
RIB lock/unlock
Differential Revision: https://reviews.freebsd.org/D36070
MFC after: 2 weeks
* Make nhgrp_get_nhops() return const struct weightened_nhop to
indicate that the list is immutable
* Make nhgrp_get_group() return the actual group, instead of
group+weight.
MFC after: 2 weeks
Convert the last remaining pieces of old-style debug messages
to the new debugging framework.
Differential Revision: https://reviews.freebsd.org/D35994
MFC after: 2 weeks
Currently, rt_addrinfo(info) serves as a main "transport" moving
state between various functions inside the routing subsystem.
As all of the fields are filled in directly by the customers, it
is problematic to maintain consistency, resulting in repeated checks
inside many functions. Additionally, there are multiple ways of
specifying the same value (RTAX_IFP vs rti_ifp / rti_ifa) and so on.
With the upcoming nhop(9) kpi it is possible to store all of the
required state in the nexthops in the consistent fashion, reducing the
need to use "info" in the KPI calls.
Finally, rt_addrinfo structure format was derived from the rtsock wire
format, which is different from other kernel routing users or netlink.
This cleanup simplifies upcoming nhop(9) kpi and netlink introduction.
Reviewed by: zlei.huang@gmail.com
Differential Revision: https://reviews.freebsd.org/D35972
MFC after: 2 weeks
Expiration time is actually a path property, not a route property.
Move its storage to nexthop to simplify upcoming nhop(9) KPI changes
and netlink introduction.
Differential Revision: https://reviews.freebsd.org/D35970
MFC after: 2 weeks
With clang 15, the following -Werror warnings are produced:
sys/net/route/route_ctl.c:130:17: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes]
vnet_rtzone_init()
^
void
sys/net/route/route_ctl.c:139:20: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes]
vnet_rtzone_destroy()
^
void
This is because vnet_rtzone_init() and vnet_rtzone_destroy() are
declared with (void) argument lists, but defined with empty argument
lists. Make the definitions match the declarations.
MFC after: 3 days
With clang 15, the following -Werror warning is produced:
sys/net/route/nhop_ctl.c:508:21: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes]
alloc_nhop_structure()
^
void
This is alloc_nhop_structure() is declared with a (void) argument list,
but defined with an empty argument list. Make the definition match the
declaration.
MFC after: 3 days
Some command definitions were forced to use DB_FUNC in order to specify
their required flags, CS_OWN or CS_MORE. Use the new macros to simplify
these.
Reviewed by: markj, jhb
MFC after: 3 days
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D35582
The function's goal is to compare old/new nhop/nexthop group for the route
and decompose it into the series of RTM_ADD/RTM_DELETE single-nhop
events, calling specified callback for each event.
Simplify it by properly leveraging the fact that both old/new groups
are sorted nhop-# ascending.
Tested by: Claudio Jeker<claudio.jeker@klarasystems.com>
Differential Revision: https://reviews.freebsd.org/D35598
MFC after: 2 weeks
Nexthops in the nexthop groups needs to be deterministically sorted
by some their property to simplify reporting cost when changing
large nexthop groups.
Fix reporting by actually sorting next hops by their indices (`wn_cmp_idx()`).
As calc_min_mpath_slots_fast() has an assumption that next hops are sorted
using their relative weight in the nexthop groups, it needs to be
addressed as well. The latter sorting is required to quickly determine the
layout of the next hops in the actual forwarding group. For example,
what's the best way to split the traffic between nhops with weights
19,31 and 47 if the maximum nexthop group width is 64?
It is worth mentioning that such sorting is only required during nexthop
group creation and is not used elsewhere. Lastly, normally all nexthop
are of the same weight. With that in mind, (a) use spare 32 bytes inside
`struct weightened_nexthop` to avoid another memory allocation and
(b) use insertion sort to sort the nexthop weights.
Reported by: thj
Tested by: Claudio Jeker<claudio.jeker@klarasystems.com>
Differential Revision: https://reviews.freebsd.org/D35599
MFC after: 2 weeks
Use unified guidelines for the severity across the routing subsystem.
Update severity for some of the already-used messages to adhere the
guidelines.
Convert rtsock logging to the new FIB_ reporting format.
MFC after: 2 weeks
RTM_CHANGE operates on a single component of the multipath route (e.g. on a single nexthop).
Search of this nexthop is peformed by iterating over each component from multipath (nexthop)
group, using check_info_match_nhop. The problem with the current code that it incorrectly
assumes that `check_info_match_nhop()` returns true value on match, while in reality it
returns an error code on failure). Fix this by properly comparing the result with 0.
Additionally, the followup code modified original necthop group instead of a new one.
Fix this by targetting new nexthop group instead.
Reported by: thj
Tested by: Claudio Jeker <claudio.jeker@klarasystems.com>
Differential Revision: https://reviews.freebsd.org/D35526
MFC after: 2 weeks
Possibly one could assert that ret should always be 0 here (that is,
that there was always an index found in the bitmask). That should be
true since a bitmask index is allocated before the nhgrp is inserted
in the ctl->gr_head list in link_nhgrp.
