17366c0a4SAlexander V. Chernikov.\" 27366c0a4SAlexander V. Chernikov.\" Copyright (C) 2022 Alexander Chernikov <melifaro@FreeBSD.org>. 37366c0a4SAlexander V. Chernikov.\" 47366c0a4SAlexander V. Chernikov.\" Redistribution and use in source and binary forms, with or without 57366c0a4SAlexander V. Chernikov.\" modification, are permitted provided that the following conditions 67366c0a4SAlexander V. Chernikov.\" are met: 77366c0a4SAlexander V. Chernikov.\" 1. Redistributions of source code must retain the above copyright 87366c0a4SAlexander V. Chernikov.\" notice, this list of conditions and the following disclaimer. 97366c0a4SAlexander V. Chernikov.\" 2. Redistributions in binary form must reproduce the above copyright 107366c0a4SAlexander V. Chernikov.\" notice, this list of conditions and the following disclaimer in the 117366c0a4SAlexander V. Chernikov.\" documentation and/or other materials provided with the distribution. 127366c0a4SAlexander V. Chernikov.\" 137366c0a4SAlexander V. Chernikov.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 147366c0a4SAlexander V. Chernikov.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 157366c0a4SAlexander V. Chernikov.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 167366c0a4SAlexander V. Chernikov.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 177366c0a4SAlexander V. Chernikov.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 187366c0a4SAlexander V. Chernikov.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 197366c0a4SAlexander V. Chernikov.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 207366c0a4SAlexander V. Chernikov.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 217366c0a4SAlexander V. Chernikov.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 227366c0a4SAlexander V. Chernikov.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 237366c0a4SAlexander V. Chernikov.\" SUCH DAMAGE. 247366c0a4SAlexander V. Chernikov.\" 25f4d3aa74SAlexander V. Chernikov.Dd November 30, 2022 267366c0a4SAlexander V. Chernikov.Dt NETLINK 4 277366c0a4SAlexander V. Chernikov.Os 287366c0a4SAlexander V. Chernikov.Sh NAME 297366c0a4SAlexander V. Chernikov.Nm Netlink 307366c0a4SAlexander V. Chernikov.Nd Kernel network configuration protocol 317366c0a4SAlexander V. Chernikov.Sh SYNOPSIS 327366c0a4SAlexander V. Chernikov.In netlink/netlink.h 337366c0a4SAlexander V. Chernikov.In netlink/netlink_route.h 347366c0a4SAlexander V. Chernikov.Ft int 350079d177SAlexander V. Chernikov.Fn socket AF_NETLINK SOCK_RAW "int family" 367366c0a4SAlexander V. Chernikov.Sh DESCRIPTION 377366c0a4SAlexander V. ChernikovNetlink is a user-kernel message-based communication protocol primarily used 387366c0a4SAlexander V. Chernikovfor network stack configuration. 397366c0a4SAlexander V. ChernikovNetlink is easily extendable and supports large dumps and event 407366c0a4SAlexander V. Chernikovnotifications, all via a single socket. 417366c0a4SAlexander V. ChernikovThe protocol is fully asynchronous, allowing one to issue and track multiple 427366c0a4SAlexander V. Chernikovrequests at once. 437366c0a4SAlexander V. ChernikovNetlink consists of multiple families, which commonly group the commands 447366c0a4SAlexander V. Chernikovbelonging to the particular kernel subsystem. 457366c0a4SAlexander V. ChernikovCurrently, the supported families are: 467366c0a4SAlexander V. Chernikov.Pp 477366c0a4SAlexander V. Chernikov.Bd -literal -offset indent -compact 487366c0a4SAlexander V. ChernikovNETLINK_ROUTE network configuration, 497366c0a4SAlexander V. ChernikovNETLINK_GENERIC "container" family 507366c0a4SAlexander V. Chernikov.Ed 517366c0a4SAlexander V. Chernikov.Pp 527366c0a4SAlexander V. ChernikovThe 537366c0a4SAlexander V. Chernikov.Dv NETLINK_ROUTE 547366c0a4SAlexander V. Chernikovfamily handles all interfaces, addresses, neighbors, routes, and VNETs 557366c0a4SAlexander V. Chernikovconfiguration. 567366c0a4SAlexander V. ChernikovMore details can be found in 577366c0a4SAlexander V. Chernikov.Xr rtnetlink 4 . 587366c0a4SAlexander V. ChernikovThe 597366c0a4SAlexander V. Chernikov.Dv NETLINK_GENERIC 607366c0a4SAlexander V. Chernikovfamily serves as a 617366c0a4SAlexander V. Chernikov.Do container Dc , 627366c0a4SAlexander V. Chernikovallowing registering other families under the 637366c0a4SAlexander V. Chernikov.Dv NETLINK_GENERIC 647366c0a4SAlexander V. Chernikovumbrella. 657366c0a4SAlexander V. ChernikovThis approach allows using a single netlink socket to interact with 667366c0a4SAlexander V. Chernikovmultiple netlink families at once. 677366c0a4SAlexander V. ChernikovMore details can be found in 687366c0a4SAlexander V. Chernikov.Xr genetlink 4 . 697366c0a4SAlexander V. Chernikov.Pp 707366c0a4SAlexander V. ChernikovNetlink has its own sockaddr structure: 717366c0a4SAlexander V. Chernikov.Bd -literal 727366c0a4SAlexander V. Chernikovstruct sockaddr_nl { 737366c0a4SAlexander V. Chernikov uint8_t nl_len; /* sizeof(sockaddr_nl) */ 747366c0a4SAlexander V. Chernikov sa_family_t nl_family; /* netlink family */ 757366c0a4SAlexander V. Chernikov uint16_t nl_pad; /* reserved, set to 0 */ 767366c0a4SAlexander V. Chernikov uint32_t nl_pid; /* automatically selected, set to 0 */ 777366c0a4SAlexander V. Chernikov uint32_t nl_groups; /* multicast groups mask to bind to */ 787366c0a4SAlexander V. Chernikov}; 797366c0a4SAlexander V. Chernikov.Ed 807366c0a4SAlexander V. Chernikov.Pp 817366c0a4SAlexander V. ChernikovTypically, filling this structure is not required for socket operations. 827366c0a4SAlexander V. ChernikovIt is presented here for completeness. 837366c0a4SAlexander V. Chernikov.Sh PROTOCOL DESCRIPTION 847366c0a4SAlexander V. ChernikovThe protocol is message-based. 857366c0a4SAlexander V. ChernikovEach message starts with the mandatory 867366c0a4SAlexander V. Chernikov.Va nlmsghdr 877366c0a4SAlexander V. Chernikovheader, followed by the family-specific header and the list of 887366c0a4SAlexander V. Chernikovtype-length-value pairs (TLVs). 897366c0a4SAlexander V. ChernikovTLVs can be nested. 907366c0a4SAlexander V. ChernikovAll headers and TLVS are padded to 4-byte boundaries. 917366c0a4SAlexander V. ChernikovEach 927366c0a4SAlexander V. Chernikov.Xr send 2 or 937366c0a4SAlexander V. Chernikov.Xr recv 2 947366c0a4SAlexander V. Chernikovsystem call may contain multiple messages. 957366c0a4SAlexander V. Chernikov.Ss BASE HEADER 967366c0a4SAlexander V. Chernikov.Bd -literal 977366c0a4SAlexander V. Chernikovstruct nlmsghdr { 987366c0a4SAlexander V. Chernikov uint32_t nlmsg_len; /* Length of message including header */ 997366c0a4SAlexander V. Chernikov uint16_t nlmsg_type; /* Message type identifier */ 1007366c0a4SAlexander V. Chernikov uint16_t nlmsg_flags; /* Flags (NLM_F_) */ 1017366c0a4SAlexander V. Chernikov uint32_t nlmsg_seq; /* Sequence number */ 1027366c0a4SAlexander V. Chernikov uint32_t nlmsg_pid; /* Sending process port ID */ 1037366c0a4SAlexander V. Chernikov}; 1047366c0a4SAlexander V. Chernikov.Ed 1057366c0a4SAlexander V. Chernikov.Pp 1067366c0a4SAlexander V. ChernikovThe 1077366c0a4SAlexander V. Chernikov.Va nlmsg_len 1087366c0a4SAlexander V. Chernikovfield stores the whole message length, in bytes, including the header. 1097366c0a4SAlexander V. ChernikovThis length has to be rounded up to the nearest 4-byte boundary when 1107366c0a4SAlexander V. Chernikoviterating over messages. 1117366c0a4SAlexander V. ChernikovThe 1127366c0a4SAlexander V. Chernikov.Va nlmsg_type 1137366c0a4SAlexander V. Chernikovfield represents the command/request type. 1147366c0a4SAlexander V. ChernikovThis value is family-specific. 1157366c0a4SAlexander V. ChernikovThe list of supported commands can be found in the relevant family 1167366c0a4SAlexander V. Chernikovheader file. 1177366c0a4SAlexander V. Chernikov.Va nlmsg_seq 1187366c0a4SAlexander V. Chernikovis a user-provided request identifier. 1197366c0a4SAlexander V. ChernikovAn application can track the operation result using the 1207366c0a4SAlexander V. Chernikov.Dv NLMSG_ERROR 1217366c0a4SAlexander V. Chernikovmessages and matching the 1227366c0a4SAlexander V. Chernikov.Va nlmsg_seq 1237366c0a4SAlexander V. Chernikov. 1247366c0a4SAlexander V. ChernikovThe 1257366c0a4SAlexander V. Chernikov.Va nlmsg_pid 1267366c0a4SAlexander V. Chernikovfield is the message sender id. 1277366c0a4SAlexander V. ChernikovThis field is optional for userland. 1287366c0a4SAlexander V. ChernikovThe kernel sender id is zero. 1297366c0a4SAlexander V. ChernikovThe 1307366c0a4SAlexander V. Chernikov.Va nlmsg_flags 1317366c0a4SAlexander V. Chernikovfield contains the message-specific flags. 1327366c0a4SAlexander V. ChernikovThe following generic flags are defined: 1337366c0a4SAlexander V. Chernikov.Pp 1347366c0a4SAlexander V. Chernikov.Bd -literal -offset indent -compact 1357366c0a4SAlexander V. ChernikovNLM_F_REQUEST Indicates that the message is an actual request to the kernel 1367366c0a4SAlexander V. ChernikovNLM_F_ACK Request an explicit ACK message with an operation result 1377366c0a4SAlexander V. Chernikov.Ed 1387366c0a4SAlexander V. Chernikov.Pp 1397366c0a4SAlexander V. ChernikovThe following generic flags are defined for the "GET" request types: 1407366c0a4SAlexander V. Chernikov.Pp 1417366c0a4SAlexander V. Chernikov.Bd -literal -offset indent -compact 1427366c0a4SAlexander V. ChernikovNLM_F_ROOT Return the whole dataset 1437366c0a4SAlexander V. ChernikovNLM_F_MATCH Return all entries matching the criteria 1447366c0a4SAlexander V. Chernikov.Ed 1457366c0a4SAlexander V. ChernikovThese two flags are typically used together, aliased to 1467366c0a4SAlexander V. Chernikov.Dv NLM_F_DUMP 1477366c0a4SAlexander V. Chernikov.Pp 1487366c0a4SAlexander V. ChernikovThe following generic flags are defined for the "NEW" request types: 1497366c0a4SAlexander V. Chernikov.Pp 1507366c0a4SAlexander V. Chernikov.Bd -literal -offset indent -compact 1517366c0a4SAlexander V. ChernikovNLM_F_CREATE Create an object if none exists 1527366c0a4SAlexander V. ChernikovNLM_F_EXCL Don't replace an object if it exists 1537366c0a4SAlexander V. ChernikovNLM_F_REPLACE Replace an existing matching object 1547366c0a4SAlexander V. ChernikovNLM_F_APPEND Append to an existing object 1557366c0a4SAlexander V. Chernikov.Ed 1567366c0a4SAlexander V. Chernikov.Pp 1577366c0a4SAlexander V. ChernikovThe following generic flags are defined for the replies: 1587366c0a4SAlexander V. Chernikov.Pp 1597366c0a4SAlexander V. Chernikov.Bd -literal -offset indent -compact 1607366c0a4SAlexander V. ChernikovNLM_F_MULTI Indicates that the message is part of the message group 1617366c0a4SAlexander V. ChernikovNLM_F_DUMP_INTR Indicates that the state dump was not completed 1627366c0a4SAlexander V. ChernikovNLM_F_DUMP_FILTERED Indicates that the dump was filtered per request 1637366c0a4SAlexander V. ChernikovNLM_F_CAPPED Indicates the original message was capped to its header 1647366c0a4SAlexander V. ChernikovNLM_F_ACK_TLVS Indicates that extended ACK TLVs were included 1657366c0a4SAlexander V. Chernikov.Ed 1667366c0a4SAlexander V. Chernikov.Ss TLVs 1677366c0a4SAlexander V. ChernikovMost messages encode their attributes as type-length-value pairs (TLVs). 1687366c0a4SAlexander V. ChernikovThe base TLV header: 1697366c0a4SAlexander V. Chernikov.Bd -literal 1707366c0a4SAlexander V. Chernikovstruct nlattr { 1717366c0a4SAlexander V. Chernikov uint16_t nla_len; /* Total attribute length */ 1727366c0a4SAlexander V. Chernikov uint16_t nla_type; /* Attribute type */ 1737366c0a4SAlexander V. Chernikov}; 1747366c0a4SAlexander V. Chernikov.Ed 1757366c0a4SAlexander V. ChernikovThe TLV type 1767366c0a4SAlexander V. Chernikov.Pq Va nla_type 1777366c0a4SAlexander V. Chernikovscope is typically the message type or group within a family. 1787366c0a4SAlexander V. ChernikovFor example, the 1797366c0a4SAlexander V. Chernikov.Dv RTN_MULTICAST 1807366c0a4SAlexander V. Chernikovtype value is only valid for 1817366c0a4SAlexander V. Chernikov.Dv RTM_NEWROUTE 1827366c0a4SAlexander V. Chernikov, 1837366c0a4SAlexander V. Chernikov.Dv RTM_DELROUTE 1847366c0a4SAlexander V. Chernikovand 1857366c0a4SAlexander V. Chernikov.Dv RTM_GETROUTE 1867366c0a4SAlexander V. Chernikovmessages. 1877366c0a4SAlexander V. ChernikovTLVs can be nested; in that case internal TLVs may have their own sub-types. 1887366c0a4SAlexander V. ChernikovAll TLVs are packed with 4-byte padding. 1897366c0a4SAlexander V. Chernikov.Ss CONTROL MESSAGES 1907366c0a4SAlexander V. ChernikovA number of generic control messages are reserved in each family. 1917366c0a4SAlexander V. Chernikov.Pp 1927366c0a4SAlexander V. Chernikov.Dv NLMSG_ERROR 1937366c0a4SAlexander V. Chernikovreports the operation result if requested, optionally followed by 1947366c0a4SAlexander V. Chernikovthe metadata TLVs. 1957366c0a4SAlexander V. ChernikovThe value of 1967366c0a4SAlexander V. Chernikov.Va nlmsg_seq 1977366c0a4SAlexander V. Chernikovis set to its value in the original messages, while 1987366c0a4SAlexander V. Chernikov.Va nlmsg_pid 1997366c0a4SAlexander V. Chernikovis set to the socket pid of the original socket. 2007366c0a4SAlexander V. ChernikovThe operation result is reported via 2017366c0a4SAlexander V. Chernikov.Vt "struct nlmsgerr": 2027366c0a4SAlexander V. Chernikov.Bd -literal 2037366c0a4SAlexander V. Chernikovstruct nlmsgerr { 2047366c0a4SAlexander V. Chernikov int error; /* Standard errno */ 2057366c0a4SAlexander V. Chernikov struct nlmsghdr msg; /* Original message header */ 2067366c0a4SAlexander V. Chernikov}; 2077366c0a4SAlexander V. Chernikov.Ed 2087366c0a4SAlexander V. ChernikovIf the 2097366c0a4SAlexander V. Chernikov.Dv NETLINK_CAP_ACK 2107366c0a4SAlexander V. Chernikovsocket option is not set, the remainder of the original message will follow. 2117366c0a4SAlexander V. ChernikovIf the 2127366c0a4SAlexander V. Chernikov.Dv NETLINK_EXT_ACK 213f4d3aa74SAlexander V. Chernikovsocket option is set, the kernel may add a 2147366c0a4SAlexander V. Chernikov.Dv NLMSGERR_ATTR_MSG 2157366c0a4SAlexander V. Chernikovstring TLV with the textual error description, optionally followed by the 2167366c0a4SAlexander V. Chernikov.Dv NLMSGERR_ATTR_OFFS 2177366c0a4SAlexander V. ChernikovTLV, indicating the offset from the message start that triggered an error. 21825c2dd2fSAlexander V. ChernikovSome operations may return additional metadata encapsulated in the 21925c2dd2fSAlexander V. Chernikov.Dv NLMSGERR_ATTR_COOKIE 22025c2dd2fSAlexander V. ChernikovTLV. 22125c2dd2fSAlexander V. ChernikovThe metadata format is specific to the operation. 222f4d3aa74SAlexander V. ChernikovIf the operation reply is a multipart message, then no 223f4d3aa74SAlexander V. Chernikov.Dv NLMSG_ERROR 224f4d3aa74SAlexander V. Chernikovreply is generated, only a 225f4d3aa74SAlexander V. Chernikov.Dv NLMSG_DONE 226f4d3aa74SAlexander V. Chernikovmessage, closing multipart sequence. 2277366c0a4SAlexander V. Chernikov.Pp 2287366c0a4SAlexander V. Chernikov.Dv NLMSG_DONE 2297366c0a4SAlexander V. Chernikovindicates the end of the message group: typically, the end of the dump. 2307366c0a4SAlexander V. ChernikovIt contains a single 2317366c0a4SAlexander V. Chernikov.Vt int 2327366c0a4SAlexander V. Chernikovfield, describing the dump result as a standard errno value. 2337366c0a4SAlexander V. Chernikov.Sh SOCKET OPTIONS 2347366c0a4SAlexander V. ChernikovNetlink supports a number of custom socket options, which can be set with 2357366c0a4SAlexander V. Chernikov.Xr setsockopt 2 2367366c0a4SAlexander V. Chernikovwith the 2377366c0a4SAlexander V. Chernikov.Dv SOL_NETLINK 2387366c0a4SAlexander V. Chernikov.Fa level : 2397366c0a4SAlexander V. Chernikov.Bl -tag -width indent 2407366c0a4SAlexander V. Chernikov.It Dv NETLINK_ADD_MEMBERSHIP 2417366c0a4SAlexander V. ChernikovSubscribes to the notifications for the specific group (int). 2427366c0a4SAlexander V. Chernikov.It Dv NETLINK_DROP_MEMBERSHIP 2437366c0a4SAlexander V. ChernikovUnsubscribes from the notifications for the specific group (int). 2447366c0a4SAlexander V. Chernikov.It Dv NETLINK_LIST_MEMBERSHIPS 2457366c0a4SAlexander V. ChernikovLists the memberships as a bitmask. 2467366c0a4SAlexander V. Chernikov.It Dv NETLINK_CAP_ACK 2477366c0a4SAlexander V. ChernikovInstructs the kernel to send the original message header in the reply 2487366c0a4SAlexander V. Chernikovwithout the message body. 2497366c0a4SAlexander V. Chernikov.It Dv NETLINK_EXT_ACK 2507366c0a4SAlexander V. ChernikovAcknowledges ability to receive additional TLVs in the ACK message. 2517366c0a4SAlexander V. Chernikov.El 2527366c0a4SAlexander V. Chernikov.Pp 2537366c0a4SAlexander V. ChernikovAdditionally, netlink overrides the following socket options from the 2547366c0a4SAlexander V. Chernikov.Dv SOL_SOCKET 2557366c0a4SAlexander V. Chernikov.Fa level : 2567366c0a4SAlexander V. Chernikov.Bl -tag -width indent 2577366c0a4SAlexander V. Chernikov.It Dv SO_RCVBUF 2587366c0a4SAlexander V. ChernikovSets the maximum size of the socket receive buffer. 2597366c0a4SAlexander V. ChernikovIf the caller has 2607366c0a4SAlexander V. Chernikov.Dv PRIV_NET_ROUTE 2617366c0a4SAlexander V. Chernikovpermission, the value can exceed the currently-set 2627366c0a4SAlexander V. Chernikov.Va kern.ipc.maxsockbuf 2637366c0a4SAlexander V. Chernikovvalue. 2647366c0a4SAlexander V. Chernikov.El 2657366c0a4SAlexander V. Chernikov.Sh SYSCTL VARIABLES 2667366c0a4SAlexander V. ChernikovA set of 2677366c0a4SAlexander V. Chernikov.Xr sysctl 8 2687366c0a4SAlexander V. Chernikovvariables is available to tweak run-time parameters: 2697366c0a4SAlexander V. Chernikov.Bl -tag -width indent 2707366c0a4SAlexander V. Chernikov.It Va net.netlink.sendspace 2717366c0a4SAlexander V. ChernikovDefault send buffer for the netlink socket. 2727366c0a4SAlexander V. ChernikovNote that the socket sendspace has to be at least as long as the longest 2737366c0a4SAlexander V. Chernikovmessage that can be transmitted via this socket. 2747366c0a4SAlexander V. Chernikov.El 2757366c0a4SAlexander V. Chernikov.Bl -tag -width indent 2767366c0a4SAlexander V. Chernikov.It Va net.netlink.recvspace 2777366c0a4SAlexander V. ChernikovDefault receive buffer for the netlink socket. 2787366c0a4SAlexander V. ChernikovNote that the socket recvspace has to be least as long as the longest 2797366c0a4SAlexander V. Chernikovmessage that can be received from this socket. 2807366c0a4SAlexander V. Chernikov.El 28128a5d88fSAlexander V. Chernikov.Bl -tag -width indent 28228a5d88fSAlexander V. Chernikov.It Va net.netlink.nl_maxsockbuf 28328a5d88fSAlexander V. ChernikovMaximum receive buffer for the netlink socket that can be set via 28428a5d88fSAlexander V. Chernikov.Dv SO_RCVBUF 28528a5d88fSAlexander V. Chernikovsocket option. 28628a5d88fSAlexander V. Chernikov.El 2877366c0a4SAlexander V. Chernikov.Sh DEBUGGING 2887366c0a4SAlexander V. ChernikovNetlink implements per-functional-unit debugging, with different severities 2897366c0a4SAlexander V. Chernikovcontrollable via the 2907366c0a4SAlexander V. Chernikov.Va net.netlink.debug 2917366c0a4SAlexander V. Chernikovbranch. 2927366c0a4SAlexander V. ChernikovThese messages are logged in the kernel message buffer and can be seen in 2937366c0a4SAlexander V. Chernikov.Xr dmesg 8 2947366c0a4SAlexander V. Chernikov. 2957366c0a4SAlexander V. ChernikovThe following severity levels are defined: 2967366c0a4SAlexander V. Chernikov.Bl -tag -width indent 2977366c0a4SAlexander V. Chernikov.It Dv LOG_DEBUG(7) 2987366c0a4SAlexander V. ChernikovRare events or per-socket errors are reported here. 2997366c0a4SAlexander V. ChernikovThis is the default level, not impacting production performance. 3007366c0a4SAlexander V. Chernikov.It Dv LOG_DEBUG2(8) 3017366c0a4SAlexander V. ChernikovSocket events such as groups memberships, privilege checks, commands and dumps 3027366c0a4SAlexander V. Chernikovare logged. 3037366c0a4SAlexander V. ChernikovThis level does not incur significant performance overhead. 3040079d177SAlexander V. Chernikov.It Dv LOG_DEBUG3(9) 3057366c0a4SAlexander V. ChernikovAll socket events, each dumped or modified entities are logged. 3067366c0a4SAlexander V. ChernikovTurning it on may result in significant performance overhead. 3077366c0a4SAlexander V. Chernikov.El 3087366c0a4SAlexander V. Chernikov.Sh ERRORS 3097366c0a4SAlexander V. ChernikovNetlink reports operation results, including errors and error metadata, by 3107366c0a4SAlexander V. Chernikovsending a 3117366c0a4SAlexander V. Chernikov.Dv NLMSG_ERROR 3127366c0a4SAlexander V. Chernikovmessage for each request message. 3137366c0a4SAlexander V. ChernikovThe following errors can be returned: 3147366c0a4SAlexander V. Chernikov.Bl -tag -width Er 3157366c0a4SAlexander V. Chernikov.It Bq Er EPERM 3167366c0a4SAlexander V. Chernikovwhen the current privileges are insufficient to perform the required operation; 3177366c0a4SAlexander V. Chernikov.It Bo Er ENOBUFS Bc or Bo Er ENOMEM Bc 3187366c0a4SAlexander V. Chernikovwhen the system runs out of memory for 3197366c0a4SAlexander V. Chernikovan internal data structure; 3207366c0a4SAlexander V. Chernikov.It Bq Er ENOTSUP 3217366c0a4SAlexander V. Chernikovwhen the requested command is not supported by the family or 3227366c0a4SAlexander V. Chernikovthe family is not supported; 3237366c0a4SAlexander V. Chernikov.It Bq Er EINVAL 3247366c0a4SAlexander V. Chernikovwhen some necessary TLVs are missing or invalid, detailed info 3257366c0a4SAlexander V. Chernikovmay be provided in NLMSGERR_ATTR_MSG and NLMSGERR_ATTR_OFFS TLVs; 3267366c0a4SAlexander V. Chernikov.It Bq Er ENOENT 3277366c0a4SAlexander V. Chernikovwhen trying to delete a non-existent object. 3287366c0a4SAlexander V. Chernikov.Pp 3297366c0a4SAlexander V. ChernikovAdditionally, a socket operation itself may fail with one of the errors 3307366c0a4SAlexander V. Chernikovspecified in 3317366c0a4SAlexander V. Chernikov.Xr socket 2 3327366c0a4SAlexander V. Chernikov, 3337366c0a4SAlexander V. Chernikov.Xr recv 2 3347366c0a4SAlexander V. Chernikovor 3357366c0a4SAlexander V. Chernikov.Xr send 2 3367366c0a4SAlexander V. Chernikov. 3377366c0a4SAlexander V. Chernikov.El 3387366c0a4SAlexander V. Chernikov.Sh SEE ALSO 339a8633361SAlexander V. Chernikov.Xr genetlink 4 , 3407366c0a4SAlexander V. Chernikov.Xr rtnetlink 4 3417366c0a4SAlexander V. Chernikov.Rs 3427366c0a4SAlexander V. Chernikov.%A "J. Salim" 3437366c0a4SAlexander V. Chernikov.%A "H. Khosravi" 3447366c0a4SAlexander V. Chernikov.%A "A. Kleen" 3457366c0a4SAlexander V. Chernikov.%A "A. Kuznetsov" 3467366c0a4SAlexander V. Chernikov.%T "Linux Netlink as an IP Services Protocol" 3477366c0a4SAlexander V. Chernikov.%O "RFC 3549" 3487366c0a4SAlexander V. Chernikov.Re 3497366c0a4SAlexander V. Chernikov.Sh HISTORY 3507366c0a4SAlexander V. ChernikovThe netlink protocol appeared in 351*6d2feb39STom Hukins.Fx 13.2 . 3527366c0a4SAlexander V. Chernikov.Sh AUTHORS 3537366c0a4SAlexander V. ChernikovThe netlink was implemented by 3547366c0a4SAlexander V. Chernikov.An -nosplit 3557366c0a4SAlexander V. Chernikov.An Alexander Chernikov Aq Mt melifaro@FreeBSD.org . 3567366c0a4SAlexander V. ChernikovIt was derived from the Google Summer of Code 2021 project by 3577366c0a4SAlexander V. Chernikov.An Ng Peng Nam Sean . 358