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_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 size_t 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 } 298