FreeBSD/Linux Kernel Cross Reference
sys/netlink/netlink_module.c

     /*-
      * 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/kernel.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);

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