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 p = malloc(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 afap = malloc(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 afap = malloc(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 newaf = malloc(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 newaf->so_accept_filter_str = malloc(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 } 299