uipc_accf.c

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    1 /*-
    2  * Copyright (c) 2000 Paycounter, Inc.
    3  * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
    4  * All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  */
   27 
   28 #include <sys/cdefs.h>
   29 __FBSDID("$FreeBSD: src/sys/kern/uipc_accf.c,v 1.11.2.5 2005/06/26 06:59:49 maxim Exp $");
   30 
   31 #define ACCEPT_FILTER_MOD
   32 
   33 #include "opt_param.h"
   34 #include <sys/param.h>
   35 #include <sys/systm.h>
   36 #include <sys/domain.h>
   37 #include <sys/kernel.h>
   38 #include <sys/lock.h>
   39 #include <sys/malloc.h>
   40 #include <sys/mbuf.h>
   41 #include <sys/module.h>
   42 #include <sys/mutex.h>
   43 #include <sys/protosw.h>
   44 #include <sys/sysctl.h>
   45 #include <sys/socket.h>
   46 #include <sys/socketvar.h>
   47 #include <sys/queue.h>
   48 
   49 static struct mtx accept_filter_mtx;
   50 MTX_SYSINIT(accept_filter, &accept_filter_mtx, "accept_filter_mtx",
   51         MTX_DEF);
   52 #define ACCEPT_FILTER_LOCK()    mtx_lock(&accept_filter_mtx)
   53 #define ACCEPT_FILTER_UNLOCK()  mtx_unlock(&accept_filter_mtx)
   54 
   55 static SLIST_HEAD(, accept_filter) accept_filtlsthd =
   56         SLIST_HEAD_INITIALIZER(&accept_filtlsthd);
   57 
   58 MALLOC_DEFINE(M_ACCF, "accf", "accept filter data");
   59 
   60 static int unloadable = 0;
   61 
   62 SYSCTL_DECL(_net_inet); /* XXX: some header should do this for me */
   63 SYSCTL_NODE(_net_inet, OID_AUTO, accf, CTLFLAG_RW, 0, "Accept filters");
   64 SYSCTL_INT(_net_inet_accf, OID_AUTO, unloadable, CTLFLAG_RW, &unloadable, 0,
   65         "Allow unload of accept filters (not recommended)");
   66 
   67 /*
   68  * Must be passed a malloc'd structure so we don't explode if the kld is
   69  * unloaded, we leak the struct on deallocation to deal with this, but if a
   70  * filter is loaded with the same name as a leaked one we re-use the entry.
   71  */
   72 int
   73 accept_filt_add(struct accept_filter *filt)
   74 {
   75         struct accept_filter *p;
   76 
   77         ACCEPT_FILTER_LOCK();
   78         SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
   79                 if (strcmp(p->accf_name, filt->accf_name) == 0)  {
   80                         if (p->accf_callback != NULL) {
   81                                 ACCEPT_FILTER_UNLOCK();
   82                                 return (EEXIST);
   83                         } else {
   84                                 p->accf_callback = filt->accf_callback;
   85                                 ACCEPT_FILTER_UNLOCK();
   86                                 FREE(filt, M_ACCF);
   87                                 return (0);
   88                         }
   89                 }
   90                                 
   91         if (p == NULL)
   92                 SLIST_INSERT_HEAD(&accept_filtlsthd, filt, accf_next);
   93         ACCEPT_FILTER_UNLOCK();
   94         return (0);
   95 }
   96 
   97 int
   98 accept_filt_del(char *name)
   99 {
  100         struct accept_filter *p;
  101 
  102         p = accept_filt_get(name);
  103         if (p == NULL)
  104                 return (ENOENT);
  105 
  106         p->accf_callback = NULL;
  107         return (0);
  108 }
  109 
  110 struct accept_filter *
  111 accept_filt_get(char *name)
  112 {
  113         struct accept_filter *p;
  114 
  115         ACCEPT_FILTER_LOCK();
  116         SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
  117                 if (strcmp(p->accf_name, name) == 0)
  118                         break;
  119         ACCEPT_FILTER_UNLOCK();
  120 
  121         return (p);
  122 }
  123 
  124 int
  125 accept_filt_generic_mod_event(module_t mod, int event, void *data)
  126 {
  127         struct accept_filter *p;
  128         struct accept_filter *accfp = (struct accept_filter *) data;
  129         int error;
  130 
  131         switch (event) {
  132         case MOD_LOAD:
  133                 MALLOC(p, struct accept_filter *, sizeof(*p), M_ACCF,
  134                     M_WAITOK);
  135                 bcopy(accfp, p, sizeof(*p));
  136                 error = accept_filt_add(p);
  137                 break;
  138 
  139         case MOD_UNLOAD:
  140                 /*
  141                  * Do not support unloading yet. we don't keep track of
  142                  * refcounts and unloading an accept filter callback and then
  143                  * having it called is a bad thing.  A simple fix would be to
  144                  * track the refcount in the struct accept_filter.
  145                  */
  146                 if (unloadable != 0) {
  147                         error = accept_filt_del(accfp->accf_name);
  148                 } else
  149                         error = EOPNOTSUPP;
  150                 break;
  151 
  152         case MOD_SHUTDOWN:
  153                 error = 0;
  154                 break;
  155 
  156         default:
  157                 error = EOPNOTSUPP;
  158                 break;
  159         }
  160 
  161         return (error);
  162 }
  163 
  164 int
  165 do_setopt_accept_filter(struct socket *so, struct sockopt *sopt)
  166 {
  167         struct accept_filter_arg *afap;
  168         struct accept_filter *afp;
  169         struct so_accf *newaf;
  170         int error = 0;
  171 
  172         newaf = NULL;
  173         afap = NULL;
  174 
  175         /*
  176          * XXXRW: Configuring accept filters should be an atomic test-and-set
  177          * operation to prevent races during setup and attach.  There may be
  178          * more general issues of racing and ordering here that are not yet
  179          * addressed by locking.
  180          */
  181         /* do not set/remove accept filters on non listen sockets */
  182         SOCK_LOCK(so);
  183         if ((so->so_options & SO_ACCEPTCONN) == 0) {
  184                 SOCK_UNLOCK(so);
  185                 return (EINVAL);
  186         }
  187 
  188         /* removing the filter */
  189         if (sopt == NULL || sopt->sopt_val == NULL) {
  190                 if (so->so_accf != NULL) {
  191                         struct so_accf *af = so->so_accf;
  192                         if (af->so_accept_filter != NULL &&
  193                                 af->so_accept_filter->accf_destroy != NULL) {
  194                                 af->so_accept_filter->accf_destroy(so);
  195                         }
  196                         if (af->so_accept_filter_str != NULL) {
  197                                 FREE(af->so_accept_filter_str, M_ACCF);
  198                         }
  199                         FREE(af, M_ACCF);
  200                         so->so_accf = NULL;
  201                 }
  202                 so->so_options &= ~SO_ACCEPTFILTER;
  203                 SOCK_UNLOCK(so);
  204                 return (0);
  205         }
  206         SOCK_UNLOCK(so);
  207 
  208         /*-
  209          * Adding a filter.
  210          *
  211          * Do memory allocation, copyin, and filter lookup now while we're
  212          * not holding any locks.  Avoids sleeping with a mutex, as well as
  213          * introducing a lock order between accept filter locks and socket
  214          * locks here.
  215          */
  216         MALLOC(afap, struct accept_filter_arg *, sizeof(*afap), M_TEMP,
  217             M_WAITOK);
  218         /* don't put large objects on the kernel stack */
  219         error = sooptcopyin(sopt, afap, sizeof *afap, sizeof *afap);
  220         afap->af_name[sizeof(afap->af_name)-1] = '\0';
  221         afap->af_arg[sizeof(afap->af_arg)-1] = '\0';
  222         if (error) {
  223                 FREE(afap, M_TEMP);
  224                 return (error);
  225         }
  226         afp = accept_filt_get(afap->af_name);
  227         if (afp == NULL) {
  228                 FREE(afap, M_TEMP);
  229                 return (ENOENT);
  230         }
  231 
  232         /*
  233          * Allocate the new accept filter instance storage.  We may have to
  234          * free it again later if we fail to attach it.  If attached
  235          * properly, 'newaf' is NULLed to avoid a free() while in use.
  236          */
  237         MALLOC(newaf, struct so_accf *, sizeof(*newaf), M_ACCF, M_WAITOK |
  238             M_ZERO);
  239         if (afp->accf_create != NULL && afap->af_name[0] != '\0') {
  240                 int len = strlen(afap->af_name) + 1;
  241                 MALLOC(newaf->so_accept_filter_str, char *, len, M_ACCF,
  242                     M_WAITOK);
  243                 strcpy(newaf->so_accept_filter_str, afap->af_name);
  244         }
  245 
  246         SOCK_LOCK(so);
  247         /* must remove previous filter first */
  248         if (so->so_accf != NULL) {
  249                 error = EINVAL;
  250                 goto out;
  251         }
  252         /*
  253          * Invoke the accf_create() method of the filter if required.
  254          * XXXRW: the socket mutex is held over this call, so the create
  255          * method cannot block.  This may be something we have to change, but
  256          * it would require addressing possible races.
  257          */
  258         if (afp->accf_create != NULL) {
  259                 newaf->so_accept_filter_arg =
  260                     afp->accf_create(so, afap->af_arg);
  261                 if (newaf->so_accept_filter_arg == NULL) {
  262                         error = EINVAL;
  263                         goto out;
  264                 }
  265         }
  266         newaf->so_accept_filter = afp;
  267         so->so_accf = newaf;
  268         so->so_options |= SO_ACCEPTFILTER;
  269         newaf = NULL;
  270 out:
  271         SOCK_UNLOCK(so);
  272         if (newaf != NULL) {
  273                 if (newaf->so_accept_filter_str != NULL)
  274                         FREE(newaf->so_accept_filter_str, M_ACCF);
  275                 FREE(newaf, M_ACCF);
  276         }
  277         if (afap != NULL)
  278                 FREE(afap, M_TEMP);
  279         return (error);
  280 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/uipc_accf.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_accf.c
