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freebsd-dev/sys/netlink/netlink_var.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.
*/
#ifndef _NETLINK_NETLINK_VAR_H_
#define _NETLINK_NETLINK_VAR_H_
#ifdef _KERNEL
#include <sys/ck.h>
#include <sys/epoch.h>
#include <sys/sysctl.h>
#include <sys/taskqueue.h>
#include <net/vnet.h>
#define NLSNDQ 65536 /* Default socket sendspace */
#define NLRCVQ 65536 /* Default socket recvspace */
struct ucred;
struct nl_io_queue {
STAILQ_HEAD(, mbuf) head;
int length;
int hiwat;
};
#define NLP_MAX_GROUPS 128
struct nlpcb {
struct socket *nl_socket;
uint64_t nl_groups[NLP_MAX_GROUPS / 64];
uint32_t nl_port;
uint32_t nl_flags;
uint32_t nl_process_id;
int nl_proto;
bool nl_active;
bool nl_bound;
bool nl_task_pending;
bool nl_tx_blocked; /* No new requests accepted */
bool nl_linux; /* true if running under compat */
bool nl_unconstrained_vnet; /* true if running under VNET jail (or without jail) */
bool nl_need_thread_setup;
struct nl_io_queue rx_queue;
struct nl_io_queue tx_queue;
struct taskqueue *nl_taskqueue;
struct task nl_task;
struct ucred *nl_cred; /* Copy of nl_socket->so_cred */
uint64_t nl_dropped_bytes;
uint64_t nl_dropped_messages;
CK_LIST_ENTRY(nlpcb) nl_next;
CK_LIST_ENTRY(nlpcb) nl_port_next;
volatile u_int nl_refcount;
struct mtx nl_lock;
struct epoch_context nl_epoch_ctx;
};
#define sotonlpcb(so) ((struct nlpcb *)(so)->so_pcb)
#define NLP_LOCK_INIT(_nlp) mtx_init(&((_nlp)->nl_lock), "nlp mtx", NULL, MTX_DEF)
#define NLP_LOCK_DESTROY(_nlp) mtx_destroy(&((_nlp)->nl_lock))
#define NLP_LOCK(_nlp) mtx_lock(&((_nlp)->nl_lock))
#define NLP_UNLOCK(_nlp) mtx_unlock(&((_nlp)->nl_lock))
#define ALIGNED_NL_SZ(_data) roundup2((((struct nlmsghdr *)(_data))->nlmsg_len), 16)
/* nl_flags */
#define NLF_CAP_ACK 0x01 /* Do not send message body with errmsg */
#define NLF_EXT_ACK 0x02 /* Allow including extended TLVs in ack */
#define NLF_STRICT 0x04 /* Perform strict header checks */
#define NLF_MSG_INFO 0x08 /* Send caller info along with the notifications */
SYSCTL_DECL(_net_netlink);
SYSCTL_DECL(_net_netlink_debug);
struct nl_io {
struct callout callout;
struct mbuf *head;
struct mbuf *last;
int64_t length;
};
struct nl_control {
CK_LIST_HEAD(nl_pid_head, nlpcb) ctl_port_head;
CK_LIST_HEAD(nlpcb_head, nlpcb) ctl_pcb_head;
CK_LIST_ENTRY(nl_control) ctl_next;
struct nl_io ctl_io;
struct rmlock ctl_lock;
};
VNET_DECLARE(struct nl_control *, nl_ctl);
#define V_nl_ctl VNET(nl_ctl)
struct sockaddr_nl;
struct sockaddr;
struct nlmsghdr;
/* netlink_module.c */
struct nl_control *vnet_nl_ctl_init(void);
int nl_verify_proto(int proto);
const char *nl_get_proto_name(int proto);
extern int netlink_unloading;
struct nl_proto_handler {
nl_handler_f cb;
const char *proto_name;
};
extern struct nl_proto_handler *nl_handlers;
/* netlink_domain.c */
void nl_send_group(struct mbuf *m, int cnt, int proto, int group_id);
void nl_osd_register(void);
void nl_osd_unregister(void);
void nl_set_thread_nlp(struct thread *td, struct nlpcb *nlp);
/* netlink_io.c */
#define NL_IOF_UNTRANSLATED 0x01
#define NL_IOF_IGNORE_LIMIT 0x02
bool nl_send_one(struct mbuf *m, struct nlpcb *nlp, int cnt, int io_flags);
void nlmsg_ack(struct nlpcb *nlp, int error, struct nlmsghdr *nlmsg,
struct nl_pstate *npt);
void nl_on_transmit(struct nlpcb *nlp);
void nl_init_io(struct nlpcb *nlp);
void nl_free_io(struct nlpcb *nlp);
void nl_taskqueue_handler(void *_arg, int pending);
int nl_receive_async(struct mbuf *m, struct socket *so);
void nl_process_receive_locked(struct nlpcb *nlp);
void nl_set_source_metadata(struct mbuf *m, int num_messages);
void nl_add_msg_info(struct mbuf *m);
/* netlink_generic.c */
struct genl_family {
const char *family_name;
uint16_t family_hdrsize;
uint16_t family_id;
uint16_t family_version;
uint16_t family_attr_max;
uint16_t family_cmd_size;
uint16_t family_num_groups;
struct genl_cmd *family_cmds;
};
struct genl_group {
struct genl_family *group_family;
const char *group_name;
};
struct genl_family *genl_get_family(uint32_t family_id);
struct genl_group *genl_get_group(uint32_t group_id);
#define MAX_FAMILIES 20
#define MAX_GROUPS 64
#define MIN_GROUP_NUM 48
#define CTRL_FAMILY_NAME "nlctrl"
struct ifnet;
struct nl_parsed_link;
struct nlattr_bmask;
struct nl_pstate;
/* Function map */
struct nl_function_wrapper {
bool (*nlmsg_add)(struct nl_writer *nw, uint32_t portid, uint32_t seq, uint16_t type,
uint16_t flags, uint32_t len);
bool (*nlmsg_refill_buffer)(struct nl_writer *nw, int required_len);
bool (*nlmsg_flush)(struct nl_writer *nw);
bool (*nlmsg_end)(struct nl_writer *nw);
void (*nlmsg_abort)(struct nl_writer *nw);
void (*nlmsg_ignore_limit)(struct nl_writer *nw);
bool (*nlmsg_get_unicast_writer)(struct nl_writer *nw, int size, struct nlpcb *nlp);
bool (*nlmsg_get_group_writer)(struct nl_writer *nw, int size, int protocol, int group_id);
bool (*nlmsg_get_chain_writer)(struct nl_writer *nw, int size, struct mbuf **pm);
bool (*nlmsg_end_dump)(struct nl_writer *nw, int error, struct nlmsghdr *hdr);
int (*nl_modify_ifp_generic)(struct ifnet *ifp, struct nl_parsed_link *lattrs,
const struct nlattr_bmask *bm, struct nl_pstate *npt);
void (*nl_store_ifp_cookie)(struct nl_pstate *npt, struct ifnet *ifp);
struct nlpcb * (*nl_get_thread_nlp)(struct thread *td);
};
void nl_set_functions(const struct nl_function_wrapper *nl);
#endif
#endif
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