xref: /freebsd/share/man/man4/rtnetlink.4 (revision 80f03e63d67ede8fedbed4bd6bf6b12ec2ab2cfb)

.\"
.\" Copyright (C) 2022 Alexander Chernikov <melifaro@FreeBSD.org>.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd November 1, 2022
.Dt RTNETLINK 4
.Os
.Sh NAME
.Nm RTNetlink
.Nd Network configuration-specific Netlink family
.Sh SYNOPSIS
.In netlink/netlink.h
.In netlink/netlink_route.h
.Ft int
.Fn socket AF_NETLINK SOCK_DGRAM NETLINK_ROUTE
.Sh DESCRIPTION
The
.Dv NETLINK_ROUTE
family aims to be the primary configuration mechanism for all
network-related tasks.
Currently it supports configuring interfaces, interface addresses, routes,
nexthops and arp/ndp neighbors.
.Sh ROUTES
All route configuration messages share the common header:
.Bd -literal
struct rtmsg {
	unsigned char	rtm_family;	/* address family */
	unsigned char	rtm_dst_len;	/* Prefix length */
	unsigned char	rtm_src_len;	/* Deprecated, set to 0 */
	unsigned char	rtm_tos;	/* Type of service (not used) */
	unsigned char	rtm_table;	/* deprecated, set to 0 */
	unsigned char	rtm_protocol;	/* Routing protocol id (RTPROT_) */
	unsigned char	rtm_scope;	/* Route distance (RT_SCOPE_) */
	unsigned char	rtm_type;	/* Route type (RTN_) */
	unsigned 	rtm_flags;	/* Route flags (not supported) */
};
.Ed
.Pp
The
.Va rtm_family
specifies the route family to be operated on.
Currently,
.Dv AF_INET6
and
.Dv AF_INET
are the only supported families.
The route prefix length is stored in
.Va rtm_dst_len
.
The caller should set the originator identity (one of the
.Dv RTPROT_
values) in
.Va rtm_protocol
.
It is useful for users and for the application itself, allowing for easy
identification of self-originated routes.
The route scope has to be set via
.Va rtm_scope
field.
The supported values are:
.Bd -literal -offset indent -compact
RT_SCOPE_UNIVERSE	Global scope
RT_SCOPE_LINK		Link scope
.Ed
.Pp
Route type needs to be set.
The defined values are:
.Bd -literal -offset indent -compact
RTN_UNICAST	Unicast route
RTN_MULTICAST	Multicast route
RTN_BLACKHOLE	Drops traffic towards destination
RTN_PROHIBIT	Drops traffic and sends reject
.Ed
.Pp
The following messages are supported:
.Ss RTM_NEWROUTE
Adds a new route.
All NL flags are supported.
Extending a multipath route requires NLM_F_APPEND flag.
.Ss RTM_DELROUTE
Tries to delete a route.
The route is specified using a combination of
.Dv RTA_DST
TLV and
.Va rtm_dst_len .
.Ss RTM_GETROUTE
Fetches a single route or all routes in the current VNET, depending on the
.Dv NLM_F_DUMP
flag.
Each route is reported as
.Dv RTM_NEWROUTE
message.
The following filters are recognised by the kernel:
.Pp
.Bd -literal -offset indent -compact
rtm_family	required family or AF_UNSPEC
RTA_TABLE	fib number or RT_TABLE_UNSPEC to return all fibs
.Ed
.Ss TLVs
.Bl -tag -width indent
.It Dv RTA_DST
(binary) IPv4/IPv6 address, depending on the
.Va rtm_family .
.It Dv RTA_OIF
(uint32_t) transmit interface index.
.It Dv RTA_GATEWAY
(binary) IPv4/IPv6 gateway address, depending on the
.Va rtm_family .
.It Dv RTA_METRICS
(nested) Container attribute, listing route properties.
The only supported sub-attribute is
.Dv RTAX_MTU , which stores path MTU as  uint32_t.
.It Dv RTA_MULTIPATH
This attribute contains multipath route nexthops with their weights.
These nexthops are represented as a sequence of
.Va rtnexthop
structures, each followed by
.Dv RTA_GATEWAY
or
.Dv RTA_VIA
attributes.
.Bd -literal
struct rtnexthop {
	unsigned short		rtnh_len;
	unsigned char		rtnh_flags;
	unsigned char		rtnh_hops;	/* nexthop weight */
	int			rtnh_ifindex;
};
.Ed
.Pp
The
.Va rtnh_len
field specifies the total nexthop info length, including both
.Va struct rtnexthop
and the following TLVs.
The
.Va rtnh_hops
field stores relative nexthop weight, used for load balancing between group
members.
The
.Va rtnh_ifindex
field contains the index of the transmit interface.
.Pp
The following TLVs can follow the structure:
.Bd -literal -offset indent -compact
RTA_GATEWAY	IPv4/IPv6 nexthop address of the gateway
RTA_VIA		IPv6 nexthop address for IPv4 route
RTA_KNH_ID	Kernel-specific index of the nexthop
.Ed
.It Dv RTA_KNH_ID
(uint32_t) (FreeBSD-specific) Auto-allocated kernel index of the nexthop.
.It Dv RTA_RTFLAGS
(uint32_t) (FreeBSD-specific) rtsock route flags.
.It Dv RTA_TABLE
(uint32_t) Fib number of the route.
Default route table is
.Dv RT_TABLE_MAIN .
To explicitely specify "all tables" one needs to set the value to
.Dv RT_TABLE_UNSPEC .
.It Dv RTA_EXPIRES
(uint32_t) seconds till path expiration.
.It Dv RTA_NH_ID
(uint32_t) useland nexthop or nexthop group index.
.El
.Ss Groups
The following groups are defined:
.Bd -literal -offset indent -compact
RTNLGRP_IPV4_ROUTE	Notifies on IPv4 route arrival/removal/change
RTNLGRP_IPV6_ROUTE	Notifies on IPv6 route arrival/removal/change
.Ed
.Sh NEXTHOPS
All nexthop/nexthop group configuration messages share the common header:
.Bd -literal
struct nhmsg {
        unsigned char	nh_family;	/* transport family */
	unsigned char	nh_scope;	/* ignored on RX, filled by kernel */
	unsigned char	nh_protocol;	/* Routing protocol that installed nh */
	unsigned char	resvd;
	unsigned int	nh_flags;	/* RTNH_F_* flags from route.h */
};
.Ed
The
.Va nh_family
specificies the gateway address family.
It can be different from route address family for IPv4 routes with IPv6
nexthops.
The
.Va nh_protocol
is similar to
.Va rtm_protocol
field, which designates originator application identity.
.Pp
The following messages are supported:
.Ss RTM_NEWNEXTHOP
Creates a new nexthop or nexthop group.
.Ss RTM_DELNEXTHOP
Deletes nexthop or nexthhop group.
The required object is specified by the
.Dv RTA_NH_ID
attribute.
.Ss RTM_GETNEXTHOP
Fetches a single nexthop or all nexthops/nexthop groups, depending on the
.Dv NLM_F_DUMP
flag.
The following filters are recognised by the kernel:
.Pp
.Bd -literal -offset indent -compact
RTA_NH_ID	nexthop or nexthtop group id
NHA_GROUPS	match only nexthtop groups
.Ed
.Ss TLVs
.Bl -tag -width indent
.It Dv RTA_NH_ID
(uint32_t) Nexthhop index used to identify particular nexthop or nexthop group.
Should be provided by userland at the nexthtop creation time.
.It Dv NHA_GROUP
This attribute designates the nexthtop group and contains all of its nexthtops
and their relative weights.
The attribute constists of a list of
.Va nexthop_grp
structures:
.Bd -literal
struct nexthop_grp {
	uint32_t	id;		/* nexhop userland index */
	uint8_t		weight;         /* weight of this nexthop */
	uint8_t		resvd1;
	uint16_t	resvd2;
};
.Ed
.It Dv NHA_GROUP_TYPE
(uint16_t) Nexthtop group type, set to one of the following types:
.Bd -literal -offset indent -compact
NEXTHOP_GRP_TYPE_MPATH	default multipath group
.Ed
.It Dv NHA_BLACKHOLE
(flag) Marks the nexthtop as blackhole.
.It Dv NHA_OIF
(uint32_t) Transmit interface index of the nexthtop.
.It Dv NHA_GATEWAY
(binary) IPv4/IPv6 gateway address
.It Dv NHA_GROUPS
(flag) Matches nexthtop groups during dump.
.El
.Ss Groups
The following groups are defined:
.Bd -literal -offset indent -compact
RTNLGRP_NEXTHOP		Notifies on nexthop/groups arrival/removal/change
.Ed
.Sh INTERFACES
All interface configuration messages share the common header:
.Bd -literal
struct ifinfomsg {
	unsigned char	ifi_family;	/* not used, set to 0 */
	unsigned char	__ifi_pad;
	unsigned short	ifi_type;	/* ARPHRD_* */
	int		ifi_index;	/* Inteface index */
	unsigned	ifi_flags;	/* IFF_* flags */
	unsigned	ifi_change;	/* IFF_* change mask */
};
.Ed
.Ss RTM_NEWLINK
Creates a new interface.
The only mandatory TLV is
.Dv IFLA_IFNAME .
.Ss RTM_DELLINK
Deletes the interface specified by
.Dv IFLA_IFNAME .
.Ss RTM_GETLINK
Fetches a single interface or all interfaces in the current VNET, depending on the
.Dv NLM_F_DUMP
flag.
Each interface is reported as a
.Dv RTM_NEWLINK
message.
The following filters are recognised by the kernel:
.Pp
.Bd -literal -offset indent -compact
ifi_index	interface index
IFLA_IFNAME	interface name
IFLA_ALT_IFNAME	interface name
.Ed
.Ss TLVs
.Bl -tag -width indent
.It Dv IFLA_ADDRESS
(binary) Llink-level interface address (MAC).
.It Dv IFLA_BROADCAST
(binary) (readonly) Link-level broadcast address.
.It Dv IFLA_IFNAME
(string) New interface name.
.It Dv IFLA_IFALIAS
(string) Interface description.
.It Dv IFLA_LINK
(uint32_t) (readonly) Interface index.
.It Dv IFLA_MASTER
(uint32_t) Parent interface index.
.It Dv IFLA_LINKINFO
(nested) Interface type-specific attributes:
.Bd -literal -offset indent -compact
IFLA_INFO_KIND		(string) interface type ("vlan")
IFLA_INFO_DATA		(nested) custom attributes
.Ed
The following types and attributes are supported:
.Bl -tag -width indent
.It Dv vlan
.Bd -literal -offset indent -compact
IFLA_VLAN_ID		(uint16_t) 802.1Q vlan id
IFLA_VLAN_PROTOCOL	(uint16_t) Protocol: ETHERTYPE_VLAN or ETHERTYPE_QINQ
.Ed
.El
.It Dv IFLA_OPERSTATE
(uint8_t) Interface operational state per RFC 2863.
Can be one of the following:
.Bd -literal -offset indent -compact
IF_OPER_UNKNOWN		status can not be determined
IF_OPER_NOTPRESENT	some (hardware) component not present
IF_OPER_DOWN		down
IF_OPER_LOWERLAYERDOWN	some lower-level interface is down
IF_OPER_TESTING		in some test mode
IF_OPER_DORMANT		"up" but waiting for some condition (802.1X)
IF_OPER_UP		ready to pass packets
.Ed
.It Dv IFLA_STATS64
(readonly) Consists of the following 64-bit counters structure:
.Bd -literal
struct rtnl_link_stats64 {
	uint64_t rx_packets;	/* total RX packets (IFCOUNTER_IPACKETS) */
	uint64_t tx_packets;	/* total TX packets (IFCOUNTER_OPACKETS) */
	uint64_t rx_bytes;	/* total RX bytes (IFCOUNTER_IBYTES) */
	uint64_t tx_bytes;	/* total TX bytes (IFCOUNTER_OBYTES) */
	uint64_t rx_errors;	/* RX errors (IFCOUNTER_IERRORS) */
	uint64_t tx_errors;	/* RX errors (IFCOUNTER_OERRORS) */
	uint64_t rx_dropped;	/* RX drop (no space in ring/no bufs) (IFCOUNTER_IQDROPS) */
	uint64_t tx_dropped;	/* TX drop (IFCOUNTER_OQDROPS) */
	uint64_t multicast;	/* RX multicast packets (IFCOUNTER_IMCASTS) */
	uint64_t collisions;	/* not supported */
	uint64_t rx_length_errors;	/* not supported */
	uint64_t rx_over_errors;	/* not supported */
	uint64_t rx_crc_errors;		/* not supported */
	uint64_t rx_frame_errors;	/* not supported */
	uint64_t rx_fifo_errors;	/* not supported */
	uint64_t rx_missed_errors;	/* not supported */
	uint64_t tx_aborted_errors;	/* not supported */
	uint64_t tx_carrier_errors;	/* not supported */
	uint64_t tx_fifo_errors;	/* not supported */
	uint64_t tx_heartbeat_errors;	/* not supported */
	uint64_t tx_window_errors;	/* not supported */
	uint64_t rx_compressed;		/* not supported */
	uint64_t tx_compressed;		/* not supported */
	uint64_t rx_nohandler;	/* dropped due to no proto handler (IFCOUNTER_NOPROTO) */
};
.Ed
.El
.Ss Groups
The following groups are defined:
.Bd -literal -offset indent -compact
RTNLGRP_LINK		Notifies on interface arrival/removal/change
.Ed
.Sh INTERFACE ADDRESSES
All interface address configuration messages share the common header:
.Bd -literal
struct ifaddrmsg {
	uint8_t		ifa_family;	/* Address family */
	uint8_t		ifa_prefixlen;	/* Prefix length */
	uint8_t		ifa_flags;	/* Address-specific flags */
	uint8_t		ifa_scope;	/* Address scope */
	uint32_t	ifa_index;	/* Link ifindex */
};
.Ed
.Pp
The
.Va ifa_family
specifies the address family of the interface address.
The
.Va ifa_prefixlen
specifies the prefix length if applicable for the address family.
The
.Va ifa_index
specifies the interface index of the target interface.
.Ss RTM_NEWADDR
Not supported
.Ss RTM_DELADDR
Not supported
.Ss RTM_GETADDR
.Ss TLVs
.Bl -tag -width indent
.It Dv IFA_ADDRESS
(binary) masked interface address or destination address for p2p interfaces.
.It Dv IFA_LOCAL
(binary) local interface address
.It Dv IFA_BROADCAST
(binary) broacast interface address
.El
.Ss Groups
The following groups are defined:
.Bd -literal -offset indent -compact
RTNLGRP_IPV4_IFADDR	Notifies on IPv4 ifaddr arrival/removal/change
RTNLGRP_IPV6_IFADDR	Notifies on IPv6 ifaddr arrival/removal/change
.Ed
.Sh NEIGHBORS
All neighbor configuration messages share the common header:
.Bd -literal
struct ndmsg {
	uint8_t		ndm_family;
	uint8_t		ndm_pad1;
	uint16_t	ndm_pad2;
	int32_t		ndm_ifindex;
	uint16_t	ndm_state;
	uint8_t		ndm_flags;
	uint8_t		ndm_type;
};
.Ed
.Pp
The
.Va ndm_family
field specifies the address family (IPv4 or IPv6) of the neighbor.
The
.Va ndm_ifindex
specifies the interface to operate on.
The
.Va ndm_state
represents the entry state according to the neighbor model.
The state can be one of the following:
.Bd -literal -offset indent -compact
NUD_INCOMPLETE		No lladdr, address resolution in progress
NUD_REACHABLE		reachable & recently resolved
NUD_STALE		has lladdr but it's stale
NUD_DELAY		has lladdr, is stale, probes delayed
NUD_PROBE		has lladdr, is stale, probes sent
NUD_FAILED		unused
.Ed
.Pp
The
.Va ndm_flags
field stores the options specific to this entry.
Available flags:
.Bd -literal -offset indent -compact
NTF_SELF		local station (LLE_IFADDR)
NTF_PROXY		proxy entry (LLE_PUB)
NTF_STICKY		permament entry (LLE_STATIC)
NTF_ROUTER		dst indicated itself as a router
.Ed
.Ss RTM_NEWNEIGH
Creates new neighbor entry.
The mandatory options are
.Dv NDA_DST ,
.Dv NDA_LLADDR
and
.Dv NDA_IFINDEX .
.Ss RTM_DELNEIGH
Deletes the neighbor entry.
The entry is specified by the combination of
.Dv NDA_DST
and
.Dv NDA_IFINDEX .
.Ss RTM_GETNEIGH
Fetches a single neighbor or all neighbors in the current VNET, depending on the
.Dv NLM_F_DUMP
flag.
Each entry is reported as
.Dv RTM_NEWNEIGH
message.
The following filters are recognised by the kernel:
.Pp
.Bd -literal -offset indent -compact
ndm_family	required family or AF_UNSPEC
ndm_ifindex	target ifindex
NDA_IFINDEX	target ifindex
.Ed
.Ss TLVs
.Bl -tag -width indent
.It Dv NDA_DST
(binary) neighbor IPv4/IPv6 address.
.It Dv NDA_LLADDR
(binary) neighbor link-level address.
.It Dv NDA_IFINDEX
(uint32_t) interface index.
.It Dv NDA_FLAGS_EXT
(uint32_t) extended version of
.Va ndm_flags .
.El
.Ss Groups
The following groups are defined:
.Bd -literal -offset indent -compact
RTNLGRP_NEIGH	Notifies on ARP/NDP neighbor  arrival/removal/change
.Ed
.Sh SEE ALSO
.Xr netlink 4 ,
.Xr route 4
.Sh HISTORY
The
.Dv NETLINK_ROUTE
protocol family appeared in
.Fx 14.0 .
.Sh AUTHORS
The netlink was implementated by
.An -nosplit
.An Alexander Chernikov Aq Mt melifaro@FreeBSD.org .
It was derived from the Google Summer of Code 2021 project by
.An Ng Peng Nam Sean .