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/6.4/sys/kern/uipc_accf.c 147300 2005-06-11 11:59:48Z maxim $");
   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_DECL(_net_inet); /* XXX: some header should do this for me */
   64 SYSCTL_NODE(_net_inet, OID_AUTO, accf, CTLFLAG_RW, 0, "Accept filters");
   65 SYSCTL_INT(_net_inet_accf, OID_AUTO, unloadable, CTLFLAG_RW, &unloadable, 0,
   66         "Allow unload of accept filters (not recommended)");
   67 
   68 /*
   69  * Must be passed a malloc'd structure so we don't explode if the kld is
   70  * unloaded, we leak the struct on deallocation to deal with this, but if a
   71  * filter is loaded with the same name as a leaked one we re-use the entry.
   72  */
   73 int
   74 accept_filt_add(struct accept_filter *filt)
   75 {
   76         struct accept_filter *p;
   77 
   78         ACCEPT_FILTER_LOCK();
   79         SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
   80                 if (strcmp(p->accf_name, filt->accf_name) == 0)  {
   81                         if (p->accf_callback != NULL) {
   82                                 ACCEPT_FILTER_UNLOCK();
   83                                 return (EEXIST);
   84                         } else {
   85                                 p->accf_callback = filt->accf_callback;
   86                                 ACCEPT_FILTER_UNLOCK();
   87                                 FREE(filt, M_ACCF);
   88                                 return (0);
   89                         }
   90                 }
   91                                 
   92         if (p == NULL)
   93                 SLIST_INSERT_HEAD(&accept_filtlsthd, filt, accf_next);
   94         ACCEPT_FILTER_UNLOCK();
   95         return (0);
   96 }
   97 
   98 int
   99 accept_filt_del(char *name)
  100 {
  101         struct accept_filter *p;
  102 
  103         p = accept_filt_get(name);
  104         if (p == NULL)
  105                 return (ENOENT);
  106 
  107         p->accf_callback = NULL;
  108         return (0);
  109 }
  110 
  111 struct accept_filter *
  112 accept_filt_get(char *name)
  113 {
  114         struct accept_filter *p;
  115 
  116         ACCEPT_FILTER_LOCK();
  117         SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
  118                 if (strcmp(p->accf_name, name) == 0)
  119                         break;
  120         ACCEPT_FILTER_UNLOCK();
  121 
  122         return (p);
  123 }
  124 
  125 int
  126 accept_filt_generic_mod_event(module_t mod, int event, void *data)
  127 {
  128         struct accept_filter *p;
  129         struct accept_filter *accfp = (struct accept_filter *) data;
  130         int error;
  131 
  132         switch (event) {
  133         case MOD_LOAD:
  134                 MALLOC(p, struct accept_filter *, sizeof(*p), M_ACCF,
  135                     M_WAITOK);
  136                 bcopy(accfp, p, sizeof(*p));
  137                 error = accept_filt_add(p);
  138                 break;
  139 
  140         case MOD_UNLOAD:
  141                 /*
  142                  * Do not support unloading yet. we don't keep track of
  143                  * refcounts and unloading an accept filter callback and then
  144                  * having it called is a bad thing.  A simple fix would be to
  145                  * track the refcount in the struct accept_filter.
  146                  */
  147                 if (unloadable != 0) {
  148                         error = accept_filt_del(accfp->accf_name);
  149                 } else
  150                         error = EOPNOTSUPP;
  151                 break;
  152 
  153         case MOD_SHUTDOWN:
  154                 error = 0;
  155                 break;
  156 
  157         default:
  158                 error = EOPNOTSUPP;
  159                 break;
  160         }
  161 
  162         return (error);
  163 }
  164 
  165 int
  166 do_getopt_accept_filter(struct socket *so, struct sockopt *sopt)
  167 {
  168         struct accept_filter_arg *afap;
  169         int error;
  170 
  171         error = 0;
  172         MALLOC(afap, struct accept_filter_arg *, sizeof(*afap), M_TEMP,
  173             M_WAITOK | M_ZERO);
  174         SOCK_LOCK(so);
  175         if ((so->so_options & SO_ACCEPTCONN) == 0) {
  176                 error = EINVAL;
  177                 goto out;
  178         }
  179         if ((so->so_options & SO_ACCEPTFILTER) == 0) {
  180                 error = EINVAL;
  181                 goto out;
  182         }
  183         strcpy(afap->af_name, so->so_accf->so_accept_filter->accf_name);
  184         if (so->so_accf->so_accept_filter_str != NULL)
  185                 strcpy(afap->af_arg, so->so_accf->so_accept_filter_str);
  186 out:
  187         SOCK_UNLOCK(so);
  188         if (error == 0)
  189                 error = sooptcopyout(sopt, afap, sizeof(*afap));
  190         FREE(afap, M_TEMP);
  191         return (error);
  192 }
  193 
  194 int
  195 do_setopt_accept_filter(struct socket *so, struct sockopt *sopt)
  196 {
  197         struct accept_filter_arg *afap;
  198         struct accept_filter *afp;
  199         struct so_accf *newaf;
  200         int error = 0;
  201 
  202         /*
  203          * Handle the simple delete case first.
  204          */
  205         if (sopt == NULL || sopt->sopt_val == NULL) {
  206                 SOCK_LOCK(so);
  207                 if ((so->so_options & SO_ACCEPTCONN) == 0) {
  208                         SOCK_UNLOCK(so);
  209                         return (EINVAL);
  210                 }
  211                 if (so->so_accf != NULL) {
  212                         struct so_accf *af = so->so_accf;
  213                         if (af->so_accept_filter != NULL &&
  214                                 af->so_accept_filter->accf_destroy != NULL) {
  215                                 af->so_accept_filter->accf_destroy(so);
  216                         }
  217                         if (af->so_accept_filter_str != NULL)
  218                                 FREE(af->so_accept_filter_str, M_ACCF);
  219                         FREE(af, M_ACCF);
  220                         so->so_accf = NULL;
  221                 }
  222                 so->so_options &= ~SO_ACCEPTFILTER;
  223                 SOCK_UNLOCK(so);
  224                 return (0);
  225         }
  226 
  227         /*
  228          * Pre-allocate any memory we may need later to avoid blocking at
  229          * untimely moments.  This does not optimize for invalid arguments.
  230          */
  231         MALLOC(afap, struct accept_filter_arg *, sizeof(*afap), M_TEMP,
  232             M_WAITOK);
  233         error = sooptcopyin(sopt, afap, sizeof *afap, sizeof *afap);
  234         afap->af_name[sizeof(afap->af_name)-1] = '\0';
  235         afap->af_arg[sizeof(afap->af_arg)-1] = '\0';
  236         if (error) {
  237                 FREE(afap, M_TEMP);
  238                 return (error);
  239         }
  240         afp = accept_filt_get(afap->af_name);
  241         if (afp == NULL) {
  242                 FREE(afap, M_TEMP);
  243                 return (ENOENT);
  244         }
  245         /*
  246          * Allocate the new accept filter instance storage.  We may
  247          * have to free it again later if we fail to attach it.  If
  248          * attached properly, 'newaf' is NULLed to avoid a free()
  249          * while in use.
  250          */
  251         MALLOC(newaf, struct so_accf *, sizeof(*newaf), M_ACCF, M_WAITOK |
  252             M_ZERO);
  253         if (afp->accf_create != NULL && afap->af_name[0] != '\0') {
  254                 int len = strlen(afap->af_name) + 1;
  255                 MALLOC(newaf->so_accept_filter_str, char *, len, M_ACCF,
  256                     M_WAITOK);
  257                 strcpy(newaf->so_accept_filter_str, afap->af_name);
  258         }
  259 
  260         /*
  261          * Require a listen socket; don't try to replace an existing filter
  262          * without first removing it.
  263          */
  264         SOCK_LOCK(so);
  265         if (((so->so_options & SO_ACCEPTCONN) == 0) ||
  266             (so->so_accf != NULL)) {
  267                 error = EINVAL;
  268                 goto out;
  269         }
  270 
  271         /*
  272          * Invoke the accf_create() method of the filter if required.  The
  273          * socket mutex is held over this call, so create methods for filters
  274          * can't block.
  275          */
  276         if (afp->accf_create != NULL) {
  277                 newaf->so_accept_filter_arg =
  278                     afp->accf_create(so, afap->af_arg);
  279                 if (newaf->so_accept_filter_arg == NULL) {
  280                         error = EINVAL;
  281                         goto out;
  282                 }
  283         }
  284         newaf->so_accept_filter = afp;
  285         so->so_accf = newaf;
  286         so->so_options |= SO_ACCEPTFILTER;
  287         newaf = NULL;
  288 out:
  289         SOCK_UNLOCK(so);
  290         if (newaf != NULL) {
  291                 if (newaf->so_accept_filter_str != NULL)
  292                         FREE(newaf->so_accept_filter_str, M_ACCF);
  293                 FREE(newaf, M_ACCF);
  294         }
  295         if (afap != NULL)
  296                 FREE(afap, M_TEMP);
  297         return (error);
  298 }

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