freebsd-dev/share/man/man4/rtnetlink.4
Tom Hukins 6d2feb39ad netlink: Fix "version introduced" documentation
netlink(4) and associated features will exist in FreeBSD 14.0 but they
will also exist in 13.2, an older version, from commits such as 02b958b1
and b309249b.

This commit needs merging to stable/13 and releng/13.2.

MFC after: 2days (needs to be in RC2)
Reviewed by: imp,melifaro
Pull Request: https://github.com/freebsd/freebsd-src/pull/651
2023-03-04 09:00:13 -07:00

542 lines
16 KiB
Groff

.\"
.\" Copyright (C) 2022 Alexander Chernikov <melifaro@FreeBSD.org>.
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.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_RAW 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 .
The following attributes are returned inside the nested
.Dv NLMSGERR_ATTR_COOKIE :
.Pp
.Bd -literal -offset indent -compact
IFLA_NEW_IFINDEX (uint32) created interface index
IFLA_IFNAME (string) created interface name
.Ed
.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
Fetches interface addresses in the current VNET matching conditions.
Each address is reported as a
.Dv RTM_NEWADDR
message.
The following filters are recognised by the kernel:
.Pp
.Bd -literal -offset indent -compact
ifa_family required family or AF_UNSPEC
ifa_index matching interface index or 0
.Ed
.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.
Set for IPv4 and p2p addresses.
.It Dv IFA_LABEL
(string) interface name.
.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 13.2 .
.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 .