sys/kern/uipc_accf.c

   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("$FreeBSD$");
  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 }