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sys/netlink/netlink_module.c

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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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/lock.h>
#include <sys/rmlock.h>
#include <sys/ck.h>
#include <sys/syslog.h>
#include <netlink/netlink.h>
#include <netlink/netlink_ctl.h>
#include <netlink/netlink_var.h>
#include <machine/atomic.h>
MALLOC_DEFINE(M_NETLINK, "netlink", "Memory used for netlink packets");
#define DEBUG_MOD_NAME nl_mod
#define DEBUG_MAX_LEVEL LOG_DEBUG3
#include <netlink/netlink_debug.h>
_DECLARE_DEBUG(LOG_DEBUG);
SYSCTL_NODE(_net, OID_AUTO, netlink, CTLFLAG_RD, 0, "");
SYSCTL_NODE(_net_netlink, OID_AUTO, debug, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, "");
#define NL_MAX_HANDLERS 20
struct nl_proto_handler _nl_handlers[NL_MAX_HANDLERS];
struct nl_proto_handler *nl_handlers = _nl_handlers;
CK_LIST_HEAD(nl_control_head, nl_control);
static struct nl_control_head vnets_head = CK_LIST_HEAD_INITIALIZER();
VNET_DEFINE(struct nl_control *, nl_ctl) = NULL;
struct mtx nl_global_mtx;
MTX_SYSINIT(nl_global_mtx, &nl_global_mtx, "global netlink lock", MTX_DEF);
#define NL_GLOBAL_LOCK() mtx_lock(&nl_global_mtx)
#define NL_GLOBAL_UNLOCK() mtx_unlock(&nl_global_mtx)
int netlink_unloading = 0;
static void
free_nl_ctl(struct nl_control *ctl)
{
rm_destroy(&ctl->ctl_lock);
free(ctl, M_NETLINK);
}
struct nl_control *
vnet_nl_ctl_init(void)
{
struct nl_control *ctl;
ctl = malloc(sizeof(struct nl_control), M_NETLINK, M_WAITOK | M_ZERO);
rm_init(&ctl->ctl_lock, "netlink lock");
CK_LIST_INIT(&ctl->ctl_port_head);
CK_LIST_INIT(&ctl->ctl_pcb_head);
NL_GLOBAL_LOCK();
struct nl_control *tmp = atomic_load_ptr(&V_nl_ctl);
if (tmp == NULL) {
atomic_store_ptr(&V_nl_ctl, ctl);
CK_LIST_INSERT_HEAD(&vnets_head, ctl, ctl_next);
NL_LOG(LOG_DEBUG2, "VNET %p init done, inserted %p into global list",
curvnet, ctl);
} else {
NL_LOG(LOG_DEBUG, "per-VNET init clash, dropping this instance");
free_nl_ctl(ctl);
ctl = tmp;
}
NL_GLOBAL_UNLOCK();
return (ctl);
}
static void
vnet_nl_ctl_destroy(const void *unused __unused)
{
struct nl_control *ctl;
/* Assume at the time all of the processes / sockets are dead */
NL_GLOBAL_LOCK();
ctl = atomic_load_ptr(&V_nl_ctl);
atomic_store_ptr(&V_nl_ctl, NULL);
if (ctl != NULL) {
NL_LOG(LOG_DEBUG2, "Removing %p from global list", ctl);
CK_LIST_REMOVE(ctl, ctl_next);
}
NL_GLOBAL_UNLOCK();
if (ctl != NULL)
free_nl_ctl(ctl);
}
VNET_SYSUNINIT(vnet_nl_ctl_destroy, SI_SUB_PROTO_IF, SI_ORDER_ANY,
vnet_nl_ctl_destroy, NULL);
int
nl_verify_proto(int proto)
{
if (proto < 0 || proto >= NL_MAX_HANDLERS) {
return (EINVAL);
}
int handler_defined = nl_handlers[proto].cb != NULL;
return (handler_defined ? 0 : EPROTONOSUPPORT);
}
const char *
nl_get_proto_name(int proto)
{
return (nl_handlers[proto].proto_name);
}
bool
netlink_register_proto(int proto, const char *proto_name, nl_handler_f handler)
{
if ((proto < 0) || (proto >= NL_MAX_HANDLERS))
return (false);
NL_GLOBAL_LOCK();
KASSERT((nl_handlers[proto].cb == NULL), ("netlink handler %d is already set", proto));
nl_handlers[proto].cb = handler;
nl_handlers[proto].proto_name = proto_name;
NL_GLOBAL_UNLOCK();
NL_LOG(LOG_DEBUG, "Registered netlink %s(%d) handler", proto_name, proto);
return (true);
}
bool
netlink_unregister_proto(int proto)
{
if ((proto < 0) || (proto >= NL_MAX_HANDLERS))
return (false);
NL_GLOBAL_LOCK();
KASSERT((nl_handlers[proto].cb != NULL), ("netlink handler %d is not set", proto));
nl_handlers[proto].cb = NULL;
nl_handlers[proto].proto_name = NULL;
NL_GLOBAL_UNLOCK();
NL_LOG(LOG_DEBUG, "Unregistered netlink proto %d handler", proto);
return (true);
}
static bool
can_unload(void)
{
struct nl_control *ctl;
bool result = true;
NL_GLOBAL_LOCK();
CK_LIST_FOREACH(ctl, &vnets_head, ctl_next) {
NL_LOG(LOG_DEBUG2, "Iterating VNET head %p", ctl);
if (!CK_LIST_EMPTY(&ctl->ctl_pcb_head)) {
NL_LOG(LOG_NOTICE, "non-empty socket list in ctl %p", ctl);
result = false;
break;
}
}
NL_GLOBAL_UNLOCK();
return (result);
}
static int
netlink_modevent(module_t mod __unused, int what, void *priv __unused)
{
int ret = 0;
switch (what) {
case MOD_LOAD:
NL_LOG(LOG_DEBUG, "Loading");
NL_LOG(LOG_NOTICE, "netlink support is in BETA stage");
break;
case MOD_UNLOAD:
NL_LOG(LOG_DEBUG, "Unload called");
if (can_unload()) {
NL_LOG(LOG_WARNING, "unloading");
netlink_unloading = 1;
} else
ret = EBUSY;
break;
default:
ret = EOPNOTSUPP;
break;
}
return (ret);
}
static moduledata_t netlink_mod = { "netlink", netlink_modevent, NULL };
DECLARE_MODULE(netlink, netlink_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
MODULE_VERSION(netlink, 1);