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freebsd-dev/sys/netlink/netlink.h
Alexander V. Chernikov 30d7e724db route: show originator PID in netlink monitor 
Replacing rtsock with netlink also means providing similar tracing facilities,
rtsock provides `route -n monitor` interface, where each message can be traced
to the originating PID.
This diff closes the feature gap between rtsock and netlink in that regard.

Netlink works slightly differently from rtsock, as it is a generic message
"broker". It calls some kernel KPIs and returns the result to the caller.
Other Netlink consumers gets notified on the changed kernel state using the
relevant subsystem callbacks. Typically, it is close to impossible to pass
some data through these KPIs to enhance the notification.

This diff approaches the problem by using osd(9) to assign the relevant
socket pointer (`'nlp`) to the per-socket taskqueue execution thread.
This change allows to recover the pointer in the aforementioned notification
callbacks and extract some additional data.
Using `osd(9)` (and adding additional metadata) to the notification receiver
comes with some additional cost attached, so this interface needs to be
enabled explicitly by using a newly-created `NETLINK_MSG_INFO` `SOL_NETLINK`
socket option.

The actual medatadata (which includes the originator PID) is provided via
control messages. To enable extensibility, the control message data is
encoded in the standard netlink(TLV-based) fashion. The list of the
currently-provided properties can be found in `nlmsginfo_attrs`.
snl(3) is extended to enable decoding of netlink messages with metadata
(`snl_read_message_dbg()` stores the parsed structure in the provided buffer).

Differential Revision: https://reviews.freebsd.org/D39391
2023-04-28 13:54:54 +00:00

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/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2021 Ng Peng Nam Sean
* Copyright (c) 2022 Alexander V. 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.
*
* Copyright (C) The Internet Society (2003). All Rights Reserved.
*
* This document and translations of it may be copied and furnished to
* others, and derivative works that comment on or otherwise explain it
* or assist in its implementation may be prepared, copied, published
* and distributed, in whole or in part, without restriction of any
* kind, provided that the above copyright notice and this paragraph are
* included on all such copies and derivative works. However, this
* document itself may not be modified in any way, such as by removing
* the copyright notice or references to the Internet Society or other
* Internet organizations, except as needed for the purpose of
* developing Internet standards in which case the procedures for
* copyrights defined in the Internet Standards process must be
* followed, or as required to translate it into languages other than
* English.
*
* The limited permissions granted above are perpetual and will not be
* revoked by the Internet Society or its successors or assignees.
*
* This document and the information contained herein is provided on an
* "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
* TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
* BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
* HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
*/
/*
* This file contains structures and constants for RFC 3549 (Netlink)
* protocol. Some values have been taken from Linux implementation.
*/
#ifndef _NETLINK_NETLINK_H_
#define _NETLINK_NETLINK_H_
#include <sys/types.h>
#include <sys/socket.h>
struct sockaddr_nl {
uint8_t nl_len; /* sizeof(sockaddr_nl) */
sa_family_t nl_family; /* netlink family */
uint16_t nl_pad; /* reserved, set to 0 */
uint32_t nl_pid; /* desired port ID, 0 for auto-select */
uint32_t nl_groups; /* multicast groups mask to bind to */
};
#define SOL_NETLINK 270
/* Netlink socket options */
#define NETLINK_ADD_MEMBERSHIP 1 /* Subscribe for the specified group notifications */
#define NETLINK_DROP_MEMBERSHIP 2 /* Unsubscribe from the specified group */
#define NETLINK_PKTINFO 3 /* XXX: not supported */
#define NETLINK_BROADCAST_ERROR 4 /* XXX: not supported */
#define NETLINK_NO_ENOBUFS 5 /* XXX: not supported */
#define NETLINK_RX_RING 6 /* XXX: not supported */
#define NETLINK_TX_RING 7 /* XXX: not supported */
#define NETLINK_LISTEN_ALL_NSID 8 /* XXX: not supported */
#define NETLINK_LIST_MEMBERSHIPS 9
#define NETLINK_CAP_ACK 10 /* Send only original message header in the reply */
#define NETLINK_EXT_ACK 11 /* Ack support for receiving additional TLVs in ack */
#define NETLINK_GET_STRICT_CHK 12 /* Strict header checking */
#define NETLINK_MSG_INFO 257 /* (FreeBSD-specific) Receive message originator data in cmsg */
/*
* RFC 3549, 2.3.2 Netlink Message Header
*/
struct nlmsghdr {
uint32_t nlmsg_len; /* Length of message including header */
uint16_t nlmsg_type; /* Message type identifier */
uint16_t nlmsg_flags; /* Flags (NLM_F_) */
uint32_t nlmsg_seq; /* Sequence number */
uint32_t nlmsg_pid; /* Sending process port ID */
};
/*
* RFC 3549, 2.3.2 standard flag bits (nlmsg_flags)
*/
#define NLM_F_REQUEST 0x01 /* Indicateds request to kernel */
#define NLM_F_MULTI 0x02 /* Message is part of a group terminated by NLMSG_DONE msg */
#define NLM_F_ACK 0x04 /* Reply with ack message containing resulting error code */
#define NLM_F_ECHO 0x08 /* (not supported) Echo this request back */
#define NLM_F_DUMP_INTR 0x10 /* Dump was inconsistent due to sequence change */
#define NLM_F_DUMP_FILTERED 0x20 /* Dump was filtered as requested */
/*
* RFC 3549, 2.3.2 Additional flag bits for GET requests
*/
#define NLM_F_ROOT 0x100 /* Return the complete table */
#define NLM_F_MATCH 0x200 /* Return all entries matching criteria */
#define NLM_F_ATOMIC 0x400 /* Return an atomic snapshot (ignored) */
#define NLM_F_DUMP (NLM_F_ROOT | NLM_F_MATCH)
/*
* RFC 3549, 2.3.2 Additional flag bits for NEW requests
*/
#define NLM_F_REPLACE 0x100 /* Replace existing matching config object */
#define NLM_F_EXCL 0x200 /* Don't replace the object if exists */
#define NLM_F_CREATE 0x400 /* Create if it does not exist */
#define NLM_F_APPEND 0x800 /* Add to end of list */
/* Modifiers to DELETE requests */
#define NLM_F_NONREC 0x100 /* Do not delete recursively */
/* Flags for ACK message */
#define NLM_F_CAPPED 0x100 /* request was capped */
#define NLM_F_ACK_TLVS 0x200 /* extended ACK TVLs were included */
/*
* RFC 3549, 2.3.2 standard message types (nlmsg_type).
*/
#define NLMSG_NOOP 0x1 /* Message is ignored. */
#define NLMSG_ERROR 0x2 /* reply error code reporting */
#define NLMSG_DONE 0x3 /* Message terminates a multipart message. */
#define NLMSG_OVERRUN 0x4 /* overrun detected, data is lost */
#define NLMSG_MIN_TYPE 0x10 /* < 0x10: reserved control messages */
/*
* Defition of numbers assigned to the netlink subsystems.
*/
#define NETLINK_ROUTE 0 /* Routing/device hook */
#define NETLINK_UNUSED 1 /* not supported */
#define NETLINK_USERSOCK 2 /* not supported */
#define NETLINK_FIREWALL 3 /* not supported */
#define NETLINK_SOCK_DIAG 4 /* not supported */
#define NETLINK_NFLOG 5 /* not supported */
#define NETLINK_XFRM 6 /* (not supported) PF_SETKEY */
#define NETLINK_SELINUX 7 /* not supported */
#define NETLINK_ISCSI 8 /* not supported */
#define NETLINK_AUDIT 9 /* not supported */
#define NETLINK_FIB_LOOKUP 10 /* not supported */
#define NETLINK_CONNECTOR 11 /* not supported */
#define NETLINK_NETFILTER 12 /* not supported */
#define NETLINK_IP6_FW 13 /* not supported */
#define NETLINK_DNRTMSG 14 /* not supported */
#define NETLINK_KOBJECT_UEVENT 15 /* not supported */
#define NETLINK_GENERIC 16 /* Generic netlink (dynamic families) */
/*
* RFC 3549, 2.3.2.2 The ACK Netlink Message
*/
struct nlmsgerr {
int error;
struct nlmsghdr msg;
};
enum nlmsgerr_attrs {
NLMSGERR_ATTR_UNUSED,
NLMSGERR_ATTR_MSG = 1, /* string, error message */
NLMSGERR_ATTR_OFFS = 2, /* u32, offset of the invalid attr from nl header */
NLMSGERR_ATTR_COOKIE = 3, /* binary, data to pass to userland */
NLMSGERR_ATTR_POLICY = 4, /* not supported */
__NLMSGERR_ATTR_MAX,
NLMSGERR_ATTR_MAX = __NLMSGERR_ATTR_MAX - 1
};
/* FreeBSD-specific debugging info */
enum nlmsginfo_attrs {
NLMSGINFO_ATTR_UNUSED,
NLMSGINFO_ATTR_PROCESS_ID = 1, /* u32, source process PID */
NLMSGINFO_ATTR_PORT_ID = 2, /* u32, source socket nl_pid */
NLMSGINFO_ATTR_SEQ_ID = 3, /* u32, source message seq_id */
};
#ifndef roundup2
#define roundup2(x, y) (((x)+((y)-1))&(~((y)-1))) /* if y is powers of two */
#endif
#define NL_ITEM_ALIGN_SIZE sizeof(uint32_t)
#define NL_ITEM_ALIGN(_len) roundup2(_len, NL_ITEM_ALIGN_SIZE)
#define NL_ITEM_DATA(_ptr, _off) ((void *)((char *)(_ptr) + _off))
#define NL_ITEM_DATA_CONST(_ptr, _off) ((const void *)((const char *)(_ptr) + _off))
#define NL_ITEM_OK(_ptr, _len, _hlen, _LEN_M) \
((_len) >= _hlen && _LEN_M(_ptr) >= _hlen && _LEN_M(_ptr) <= (_len))
#define NL_ITEM_NEXT(_ptr, _LEN_M) ((typeof(_ptr))((char *)(_ptr) + _LEN_M(_ptr)))
#define NL_ITEM_ITER(_ptr, _len, _LEN_MACRO) \
((_len) -= _LEN_MACRO(_ptr), NL_ITEM_NEXT(_ptr, _LEN_MACRO))
#ifndef _KERNEL
/* part of netlink(3) API */
#define NLMSG_ALIGNTO NL_ITEM_ALIGN_SIZE
#define NLMSG_ALIGN(_len) NL_ITEM_ALIGN(_len)
#define NLMSG_HDRLEN ((int)sizeof(struct nlmsghdr))
#define NLMSG_LENGTH(_len) ((_len) + NLMSG_HDRLEN)
#define NLMSG_SPACE(_len) NLMSG_ALIGN(NLMSG_LENGTH(_len))
#define NLMSG_DATA(_hdr) NL_ITEM_DATA(_hdr, NLMSG_HDRLEN)
#define _NLMSG_LEN(_hdr) ((int)(_hdr)->nlmsg_len)
#define _NLMSG_ALIGNED_LEN(_hdr) NLMSG_ALIGN(_NLMSG_LEN(_hdr))
#define NLMSG_OK(_hdr, _len) NL_ITEM_OK(_hdr, _len, NLMSG_HDRLEN, _NLMSG_LEN)
#define NLMSG_PAYLOAD(_hdr,_len) (_NLMSG_LEN(_hdr) - NLMSG_SPACE((_len)))
#define NLMSG_NEXT(_hdr, _len) NL_ITEM_ITER(_hdr, _len, _NLMSG_ALIGNED_LEN)
#else
#define NLMSG_ALIGNTO 4U
#define NLMSG_ALIGN(len) (((len) + NLMSG_ALIGNTO - 1) & ~(NLMSG_ALIGNTO - 1))
#define NLMSG_HDRLEN ((int)NLMSG_ALIGN(sizeof(struct nlmsghdr)))
#endif
/*
* Base netlink attribute TLV header.
*/
struct nlattr {
uint16_t nla_len; /* Total attribute length */
uint16_t nla_type; /* Attribute type */
};
/*
*
* nl_type field enconding:
*
* 0 1
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |N|O| Attribute type |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* N - attribute contains other attributes (mostly unused)
* O - encoded in network byte order (mostly unused)
* Note: N & O are mutually exclusive
*
* Note: attribute type value scope normally is either parent attribute
* or the message/message group.
*/
#define NLA_F_NESTED (1 << 15)
#define NLA_F_NET_BYTEORDER (1 << 14)
#define NLA_TYPE_MASK ~(NLA_F_NESTED | NLA_F_NET_BYTEORDER)
#ifndef _KERNEL
#define NLA_ALIGNTO NL_ITEM_ALIGN_SIZE
#define NLA_ALIGN(_len) NL_ITEM_ALIGN(_len)
#define NLA_HDRLEN ((int)sizeof(struct nlattr))
#endif
#endif
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