The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 2000 Paycounter, Inc.
    3  * Copyright (c) 2005 Robert N. M. Watson
    4  * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   26  * SUCH DAMAGE.
   27  */
   28 
   29 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD: releng/11.0/sys/kern/uipc_accf.c 269142 2014-07-26 19:27:34Z marcel $");
   31 
   32 #define ACCEPT_FILTER_MOD
   33 
   34 #include "opt_param.h"
   35 #include <sys/param.h>
   36 #include <sys/systm.h>
   37 #include <sys/domain.h>
   38 #include <sys/kernel.h>
   39 #include <sys/lock.h>
   40 #include <sys/malloc.h>
   41 #include <sys/mbuf.h>
   42 #include <sys/module.h>
   43 #include <sys/mutex.h>
   44 #include <sys/protosw.h>
   45 #include <sys/sysctl.h>
   46 #include <sys/socket.h>
   47 #include <sys/socketvar.h>
   48 #include <sys/queue.h>
   49 
   50 static struct mtx accept_filter_mtx;
   51 MTX_SYSINIT(accept_filter, &accept_filter_mtx, "accept_filter_mtx",
   52         MTX_DEF);
   53 #define ACCEPT_FILTER_LOCK()    mtx_lock(&accept_filter_mtx)
   54 #define ACCEPT_FILTER_UNLOCK()  mtx_unlock(&accept_filter_mtx)
   55 
   56 static SLIST_HEAD(, accept_filter) accept_filtlsthd =
   57         SLIST_HEAD_INITIALIZER(accept_filtlsthd);
   58 
   59 MALLOC_DEFINE(M_ACCF, "accf", "accept filter data");
   60 
   61 static int unloadable = 0;
   62 
   63 SYSCTL_NODE(_net, OID_AUTO, accf, CTLFLAG_RW, 0, "Accept filters");
   64 SYSCTL_INT(_net_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                 p = malloc(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_getopt_accept_filter(struct socket *so, struct sockopt *sopt)
  166 {
  167         struct accept_filter_arg *afap;
  168         int error;
  169 
  170         error = 0;
  171         afap = malloc(sizeof(*afap), M_TEMP,
  172             M_WAITOK | M_ZERO);
  173         SOCK_LOCK(so);
  174         if ((so->so_options & SO_ACCEPTCONN) == 0) {
  175                 error = EINVAL;
  176                 goto out;
  177         }
  178         if ((so->so_options & SO_ACCEPTFILTER) == 0) {
  179                 error = EINVAL;
  180                 goto out;
  181         }
  182         strcpy(afap->af_name, so->so_accf->so_accept_filter->accf_name);
  183         if (so->so_accf->so_accept_filter_str != NULL)
  184                 strcpy(afap->af_arg, so->so_accf->so_accept_filter_str);
  185 out:
  186         SOCK_UNLOCK(so);
  187         if (error == 0)
  188                 error = sooptcopyout(sopt, afap, sizeof(*afap));
  189         free(afap, M_TEMP);
  190         return (error);
  191 }
  192 
  193 int
  194 do_setopt_accept_filter(struct socket *so, struct sockopt *sopt)
  195 {
  196         struct accept_filter_arg *afap;
  197         struct accept_filter *afp;
  198         struct so_accf *newaf;
  199         int error = 0;
  200 
  201         /*
  202          * Handle the simple delete case first.
  203          */
  204         if (sopt == NULL || sopt->sopt_val == NULL) {
  205                 SOCK_LOCK(so);
  206                 if ((so->so_options & SO_ACCEPTCONN) == 0) {
  207                         SOCK_UNLOCK(so);
  208                         return (EINVAL);
  209                 }
  210                 if (so->so_accf != NULL) {
  211                         struct so_accf *af = so->so_accf;
  212                         if (af->so_accept_filter != NULL &&
  213                                 af->so_accept_filter->accf_destroy != NULL) {
  214                                 af->so_accept_filter->accf_destroy(so);
  215                         }
  216                         if (af->so_accept_filter_str != NULL)
  217                                 free(af->so_accept_filter_str, M_ACCF);
  218                         free(af, M_ACCF);
  219                         so->so_accf = NULL;
  220                 }
  221                 so->so_options &= ~SO_ACCEPTFILTER;
  222                 SOCK_UNLOCK(so);
  223                 return (0);
  224         }
  225 
  226         /*
  227          * Pre-allocate any memory we may need later to avoid blocking at
  228          * untimely moments.  This does not optimize for invalid arguments.
  229          */
  230         afap = malloc(sizeof(*afap), M_TEMP,
  231             M_WAITOK);
  232         error = sooptcopyin(sopt, afap, sizeof *afap, sizeof *afap);
  233         afap->af_name[sizeof(afap->af_name)-1] = '\0';
  234         afap->af_arg[sizeof(afap->af_arg)-1] = '\0';
  235         if (error) {
  236                 free(afap, M_TEMP);
  237                 return (error);
  238         }
  239         afp = accept_filt_get(afap->af_name);
  240         if (afp == NULL) {
  241                 free(afap, M_TEMP);
  242                 return (ENOENT);
  243         }
  244         /*
  245          * Allocate the new accept filter instance storage.  We may
  246          * have to free it again later if we fail to attach it.  If
  247          * attached properly, 'newaf' is NULLed to avoid a free()
  248          * while in use.
  249          */
  250         newaf = malloc(sizeof(*newaf), M_ACCF, M_WAITOK |
  251             M_ZERO);
  252         if (afp->accf_create != NULL && afap->af_name[0] != '\0') {
  253                 int len = strlen(afap->af_name) + 1;
  254                 newaf->so_accept_filter_str = malloc(len, M_ACCF,
  255                     M_WAITOK);
  256                 strcpy(newaf->so_accept_filter_str, afap->af_name);
  257         }
  258 
  259         /*
  260          * Require a listen socket; don't try to replace an existing filter
  261          * without first removing it.
  262          */
  263         SOCK_LOCK(so);
  264         if (((so->so_options & SO_ACCEPTCONN) == 0) ||
  265             (so->so_accf != NULL)) {
  266                 error = EINVAL;
  267                 goto out;
  268         }
  269 
  270         /*
  271          * Invoke the accf_create() method of the filter if required.  The
  272          * socket mutex is held over this call, so create methods for filters
  273          * can't block.
  274          */
  275         if (afp->accf_create != NULL) {
  276                 newaf->so_accept_filter_arg =
  277                     afp->accf_create(so, afap->af_arg);
  278                 if (newaf->so_accept_filter_arg == NULL) {
  279                         error = EINVAL;
  280                         goto out;
  281                 }
  282         }
  283         newaf->so_accept_filter = afp;
  284         so->so_accf = newaf;
  285         so->so_options |= SO_ACCEPTFILTER;
  286         newaf = NULL;
  287 out:
  288         SOCK_UNLOCK(so);
  289         if (newaf != NULL) {
  290                 if (newaf->so_accept_filter_str != NULL)
  291                         free(newaf->so_accept_filter_str, M_ACCF);
  292                 free(newaf, M_ACCF);
  293         }
  294         if (afap != NULL)
  295                 free(afap, M_TEMP);
  296         return (error);
  297 }

Cache object: 652781b8f43efdbbee15cc8bb0c4c21d


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