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("$FreeBSD$"); 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 } 309