uipc_accf.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 2000 Paycounter, Inc.
    5  * Copyright (c) 2005 Robert N. M. Watson
    6  * Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
    7  * All rights reserved.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   28  * SUCH DAMAGE.
   29  */
   30 
   31 #include <sys/cdefs.h>
   32 __FBSDID("$FreeBSD: releng/12.0/sys/kern/uipc_accf.c 326271 2017-11-27 15:20:12Z pfg $");
   33 
   34 #define ACCEPT_FILTER_MOD
   35 
   36 #include "opt_param.h"
   37 #include <sys/param.h>
   38 #include <sys/systm.h>
   39 #include <sys/domain.h>
   40 #include <sys/kernel.h>
   41 #include <sys/lock.h>
   42 #include <sys/malloc.h>
   43 #include <sys/mbuf.h>
   44 #include <sys/module.h>
   45 #include <sys/mutex.h>
   46 #include <sys/protosw.h>
   47 #include <sys/sysctl.h>
   48 #include <sys/socket.h>
   49 #include <sys/socketvar.h>
   50 #include <sys/queue.h>
   51 
   52 static struct mtx accept_filter_mtx;
   53 MTX_SYSINIT(accept_filter, &accept_filter_mtx, "accept_filter_mtx",
   54         MTX_DEF);
   55 #define ACCEPT_FILTER_LOCK()    mtx_lock(&accept_filter_mtx)
   56 #define ACCEPT_FILTER_UNLOCK()  mtx_unlock(&accept_filter_mtx)
   57 
   58 static SLIST_HEAD(, accept_filter) accept_filtlsthd =
   59         SLIST_HEAD_INITIALIZER(accept_filtlsthd);
   60 
   61 MALLOC_DEFINE(M_ACCF, "accf", "accept filter data");
   62 
   63 static int unloadable = 0;
   64 
   65 SYSCTL_NODE(_net, OID_AUTO, accf, CTLFLAG_RW, 0, "Accept filters");
   66 SYSCTL_INT(_net_accf, OID_AUTO, unloadable, CTLFLAG_RW, &unloadable, 0,
   67         "Allow unload of accept filters (not recommended)");
   68 
   69 /*
   70  * Must be passed a malloc'd structure so we don't explode if the kld is
   71  * unloaded, we leak the struct on deallocation to deal with this, but if a
   72  * filter is loaded with the same name as a leaked one we re-use the entry.
   73  */
   74 int
   75 accept_filt_add(struct accept_filter *filt)
   76 {
   77         struct accept_filter *p;
   78 
   79         ACCEPT_FILTER_LOCK();
   80         SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
   81                 if (strcmp(p->accf_name, filt->accf_name) == 0)  {
   82                         if (p->accf_callback != NULL) {
   83                                 ACCEPT_FILTER_UNLOCK();
   84                                 return (EEXIST);
   85                         } else {
   86                                 p->accf_callback = filt->accf_callback;
   87                                 ACCEPT_FILTER_UNLOCK();
   88                                 free(filt, M_ACCF);
   89                                 return (0);
   90                         }
   91                 }
   92                                 
   93         if (p == NULL)
   94                 SLIST_INSERT_HEAD(&accept_filtlsthd, filt, accf_next);
   95         ACCEPT_FILTER_UNLOCK();
   96         return (0);
   97 }
   98 
   99 int
  100 accept_filt_del(char *name)
  101 {
  102         struct accept_filter *p;
  103 
  104         p = accept_filt_get(name);
  105         if (p == NULL)
  106                 return (ENOENT);
  107 
  108         p->accf_callback = NULL;
  109         return (0);
  110 }
  111 
  112 struct accept_filter *
  113 accept_filt_get(char *name)
  114 {
  115         struct accept_filter *p;
  116 
  117         ACCEPT_FILTER_LOCK();
  118         SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
  119                 if (strcmp(p->accf_name, name) == 0)
  120                         break;
  121         ACCEPT_FILTER_UNLOCK();
  122 
  123         return (p);
  124 }
  125 
  126 int
  127 accept_filt_generic_mod_event(module_t mod, int event, void *data)
  128 {
  129         struct accept_filter *p;
  130         struct accept_filter *accfp = (struct accept_filter *) data;
  131         int error;
  132 
  133         switch (event) {
  134         case MOD_LOAD:
  135                 p = malloc(sizeof(*p), M_ACCF, 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 accept_filt_getopt(struct socket *so, struct sockopt *sopt)
  167 {
  168         struct accept_filter_arg *afap;
  169         int error;
  170 
  171         error = 0;
  172         afap = malloc(sizeof(*afap), M_TEMP, 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->sol_accept_filter == NULL) {
  179                 error = EINVAL;
  180                 goto out;
  181         }
  182         strcpy(afap->af_name, so->sol_accept_filter->accf_name);
  183         if (so->sol_accept_filter_str != NULL)
  184                 strcpy(afap->af_arg, so->sol_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 accept_filt_setopt(struct socket *so, struct sockopt *sopt)
  195 {
  196         struct accept_filter_arg *afap;
  197         struct accept_filter *afp;
  198         char *accept_filter_str = NULL;
  199         void *accept_filter_arg = NULL;
  200         int error;
  201 
  202         /*
  203          * Handle the simple delete case first.
  204          */
  205         if (sopt == NULL || sopt->sopt_val == NULL) {
  206                 struct socket *sp, *sp1;
  207                 int wakeup;
  208 
  209                 SOCK_LOCK(so);
  210                 if ((so->so_options & SO_ACCEPTCONN) == 0) {
  211                         SOCK_UNLOCK(so);
  212                         return (EINVAL);
  213                 }
  214                 if (so->sol_accept_filter == NULL) {
  215                         SOCK_UNLOCK(so);
  216                         return (0);
  217                 }
  218                 if (so->sol_accept_filter->accf_destroy != NULL)
  219                         so->sol_accept_filter->accf_destroy(so);
  220                 if (so->sol_accept_filter_str != NULL)
  221                         free(so->sol_accept_filter_str, M_ACCF);
  222                 so->sol_accept_filter = NULL;
  223                 so->sol_accept_filter_arg = NULL;
  224                 so->sol_accept_filter_str = NULL;
  225                 so->so_options &= ~SO_ACCEPTFILTER;
  226 
  227                 /*
  228                  * Move from incomplete queue to complete only those
  229                  * connections, that are blocked by us.
  230                  */
  231                 wakeup = 0;
  232                 TAILQ_FOREACH_SAFE(sp, &so->sol_incomp, so_list, sp1) {
  233                         SOCK_LOCK(sp);
  234                         if (sp->so_options & SO_ACCEPTFILTER) {
  235                                 TAILQ_REMOVE(&so->sol_incomp, sp, so_list);
  236                                 TAILQ_INSERT_TAIL(&so->sol_comp, sp, so_list);
  237                                 sp->so_qstate = SQ_COMP;
  238                                 sp->so_options &= ~SO_ACCEPTFILTER;
  239                                 so->sol_incqlen--;
  240                                 so->sol_qlen++;
  241                                 wakeup = 1;
  242                         }
  243                         SOCK_UNLOCK(sp);
  244                 }
  245                 if (wakeup)
  246                         solisten_wakeup(so);  /* unlocks */
  247                 else
  248                         SOLISTEN_UNLOCK(so);
  249                 return (0);
  250         }
  251 
  252         /*
  253          * Pre-allocate any memory we may need later to avoid blocking at
  254          * untimely moments.  This does not optimize for invalid arguments.
  255          */
  256         afap = malloc(sizeof(*afap), M_TEMP, M_WAITOK);
  257         error = sooptcopyin(sopt, afap, sizeof *afap, sizeof *afap);
  258         afap->af_name[sizeof(afap->af_name)-1] = '\0';
  259         afap->af_arg[sizeof(afap->af_arg)-1] = '\0';
  260         if (error) {
  261                 free(afap, M_TEMP);
  262                 return (error);
  263         }
  264         afp = accept_filt_get(afap->af_name);
  265         if (afp == NULL) {
  266                 free(afap, M_TEMP);
  267                 return (ENOENT);
  268         }
  269         if (afp->accf_create != NULL && afap->af_name[0] != '\0') {
  270                 size_t len = strlen(afap->af_name) + 1;
  271                 accept_filter_str = malloc(len, M_ACCF, M_WAITOK);
  272                 strcpy(accept_filter_str, afap->af_name);
  273         }
  274 
  275         /*
  276          * Require a listen socket; don't try to replace an existing filter
  277          * without first removing it.
  278          */
  279         SOCK_LOCK(so);
  280         if ((so->so_options & SO_ACCEPTCONN) == 0 ||
  281             so->sol_accept_filter != NULL) {
  282                 error = EINVAL;
  283                 goto out;
  284         }
  285 
  286         /*
  287          * Invoke the accf_create() method of the filter if required.  The
  288          * socket mutex is held over this call, so create methods for filters
  289          * can't block.
  290          */
  291         if (afp->accf_create != NULL) {
  292                 accept_filter_arg = afp->accf_create(so, afap->af_arg);
  293                 if (accept_filter_arg == NULL) {
  294                         error = EINVAL;
  295                         goto out;
  296                 }
  297         }
  298         so->sol_accept_filter = afp;
  299         so->sol_accept_filter_arg = accept_filter_arg;
  300         so->sol_accept_filter_str = accept_filter_str;
  301         so->so_options |= SO_ACCEPTFILTER;
  302 out:
  303         SOCK_UNLOCK(so);
  304         if (accept_filter_str != NULL)
  305                 free(accept_filter_str, M_ACCF);
  306         free(afap, M_TEMP);
  307         return (error);
  308 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/uipc_accf.c

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