uipc_accf.c revision 142058
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: head/sys/kern/uipc_accf.c 142058 2005-02-18 18:54:42Z rwatson $"); 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 49static struct mtx accept_filter_mtx; 50MTX_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 55static SLIST_HEAD(, accept_filter) accept_filtlsthd = 56 SLIST_HEAD_INITIALIZER(&accept_filtlsthd); 57 58MALLOC_DEFINE(M_ACCF, "accf", "accept filter data"); 59 60static int unloadable = 0; 61 62SYSCTL_DECL(_net_inet); /* XXX: some header should do this for me */ 63SYSCTL_NODE(_net_inet, OID_AUTO, accf, CTLFLAG_RW, 0, "Accept filters"); 64SYSCTL_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 */ 72int 73accept_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 97int 98accept_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 110struct accept_filter * 111accept_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 124int 125accept_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 164int 165do_setopt_accept_filter(so, sopt) 166 struct socket *so; 167 struct sockopt *sopt; 168{ 169 struct accept_filter_arg *afap; 170 struct accept_filter *afp; 171 struct so_accf *newaf; 172 int error = 0; 173 174 newaf = NULL; 175 afap = NULL; 176 177 /* 178 * XXXRW: Configuring accept filters should be an atomic test-and-set 179 * operation to prevent races during setup and attach. There may be 180 * more general issues of racing and ordering here that are not yet 181 * addressed by locking. 182 */ 183 /* do not set/remove accept filters on non listen sockets */ 184 SOCK_LOCK(so); 185 if ((so->so_options & SO_ACCEPTCONN) == 0) { 186 SOCK_UNLOCK(so); 187 return (EINVAL); 188 } 189 190 /* removing the filter */ 191 if (sopt == NULL) { 192 if (so->so_accf != NULL) { 193 struct so_accf *af = so->so_accf; 194 if (af->so_accept_filter != NULL && 195 af->so_accept_filter->accf_destroy != NULL) { 196 af->so_accept_filter->accf_destroy(so); 197 } 198 if (af->so_accept_filter_str != NULL) { 199 FREE(af->so_accept_filter_str, M_ACCF); 200 } 201 FREE(af, M_ACCF); 202 so->so_accf = NULL; 203 } 204 so->so_options &= ~SO_ACCEPTFILTER; 205 SOCK_UNLOCK(so); 206 return (0); 207 } 208 SOCK_UNLOCK(so); 209 210 /*- 211 * Adding a filter. 212 * 213 * Do memory allocation, copyin, and filter lookup now while we're 214 * not holding any locks. Avoids sleeping with a mutex, as well as 215 * introducing a lock order between accept filter locks and socket 216 * locks here. 217 */ 218 MALLOC(afap, struct accept_filter_arg *, sizeof(*afap), M_TEMP, 219 M_WAITOK); 220 /* don't put large objects on the kernel stack */ 221 error = sooptcopyin(sopt, afap, sizeof *afap, sizeof *afap); 222 afap->af_name[sizeof(afap->af_name)-1] = '\0'; 223 afap->af_arg[sizeof(afap->af_arg)-1] = '\0'; 224 if (error) { 225 FREE(afap, M_TEMP); 226 return (error); 227 } 228 afp = accept_filt_get(afap->af_name); 229 if (afp == NULL) { 230 FREE(afap, M_TEMP); 231 return (ENOENT); 232 } 233 234 /* 235 * Allocate the new accept filter instance storage. We may have to 236 * free it again later if we fail to attach it. If attached 237 * properly, 'newaf' is NULLed to avoid a free() while in use. 238 */ 239 MALLOC(newaf, struct so_accf *, sizeof(*newaf), M_ACCF, M_WAITOK | 240 M_ZERO); 241 if (afp->accf_create != NULL && afap->af_name[0] != '\0') { 242 int len = strlen(afap->af_name) + 1; 243 MALLOC(newaf->so_accept_filter_str, char *, len, M_ACCF, 244 M_WAITOK); 245 strcpy(newaf->so_accept_filter_str, afap->af_name); 246 } 247 248 SOCK_LOCK(so); 249 /* must remove previous filter first */ 250 if (so->so_accf != NULL) { 251 error = EINVAL; 252 goto out; 253 } 254 /* 255 * Invoke the accf_create() method of the filter if required. 256 * XXXRW: the socket mutex is held over this call, so the create 257 * method cannot block. This may be something we have to change, but 258 * it would require addressing possible races. 259 */ 260 if (afp->accf_create != NULL) { 261 newaf->so_accept_filter_arg = 262 afp->accf_create(so, afap->af_arg); 263 if (newaf->so_accept_filter_arg == NULL) { 264 error = EINVAL; 265 goto out; 266 } 267 } 268 newaf->so_accept_filter = afp; 269 so->so_accf = newaf; 270 so->so_options |= SO_ACCEPTFILTER; 271 newaf = NULL; 272out: 273 SOCK_UNLOCK(so); 274 if (newaf != NULL) { 275 if (newaf->so_accept_filter_str != NULL) 276 FREE(newaf->so_accept_filter_str, M_ACCF); 277 FREE(newaf, M_ACCF); 278 } 279 if (afap != NULL) 280 FREE(afap, M_TEMP); 281 return (error); 282} 283