1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 #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 | CTLFLAG_MPSAFE, 0, 64 "Accept filters"); 65 SYSCTL_INT(_net_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, 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 accept_filt_getopt(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, M_WAITOK | M_ZERO); 172 SOCK_LOCK(so); 173 if (!SOLISTENING(so)) { 174 error = EINVAL; 175 goto out; 176 } 177 if (so->sol_accept_filter == NULL) { 178 error = EINVAL; 179 goto out; 180 } 181 strcpy(afap->af_name, so->sol_accept_filter->accf_name); 182 if (so->sol_accept_filter_str != NULL) 183 strcpy(afap->af_arg, so->sol_accept_filter_str); 184 out: 185 SOCK_UNLOCK(so); 186 if (error == 0) 187 error = sooptcopyout(sopt, afap, sizeof(*afap)); 188 free(afap, M_TEMP); 189 return (error); 190 } 191 192 int 193 accept_filt_setopt(struct socket *so, struct sockopt *sopt) 194 { 195 struct accept_filter_arg *afap; 196 struct accept_filter *afp; 197 char *accept_filter_str = NULL; 198 void *accept_filter_arg = NULL; 199 int error; 200 201 /* 202 * Handle the simple delete case first. 203 */ 204 if (sopt == NULL || sopt->sopt_val == NULL) { 205 struct socket *sp, *sp1; 206 int wakeup; 207 208 SOCK_LOCK(so); 209 if (!SOLISTENING(so)) { 210 SOCK_UNLOCK(so); 211 return (EINVAL); 212 } 213 if (so->sol_accept_filter == NULL) { 214 SOCK_UNLOCK(so); 215 return (0); 216 } 217 if (so->sol_accept_filter->accf_destroy != NULL) 218 so->sol_accept_filter->accf_destroy(so); 219 if (so->sol_accept_filter_str != NULL) 220 free(so->sol_accept_filter_str, M_ACCF); 221 so->sol_accept_filter = NULL; 222 so->sol_accept_filter_arg = NULL; 223 so->sol_accept_filter_str = NULL; 224 so->so_options &= ~SO_ACCEPTFILTER; 225 226 /* 227 * Move from incomplete queue to complete only those 228 * connections, that are blocked by us. 229 */ 230 wakeup = 0; 231 TAILQ_FOREACH_SAFE(sp, &so->sol_incomp, so_list, sp1) { 232 SOCK_LOCK(sp); 233 if (sp->so_options & SO_ACCEPTFILTER) { 234 TAILQ_REMOVE(&so->sol_incomp, sp, so_list); 235 TAILQ_INSERT_TAIL(&so->sol_comp, sp, so_list); 236 sp->so_qstate = SQ_COMP; 237 sp->so_options &= ~SO_ACCEPTFILTER; 238 so->sol_incqlen--; 239 so->sol_qlen++; 240 wakeup = 1; 241 } 242 SOCK_UNLOCK(sp); 243 } 244 if (wakeup) 245 solisten_wakeup(so); /* unlocks */ 246 else 247 SOLISTEN_UNLOCK(so); 248 return (0); 249 } 250 251 /* 252 * Pre-allocate any memory we may need later to avoid blocking at 253 * untimely moments. This does not optimize for invalid arguments. 254 */ 255 afap = malloc(sizeof(*afap), M_TEMP, M_WAITOK); 256 error = sooptcopyin(sopt, afap, sizeof *afap, sizeof *afap); 257 afap->af_name[sizeof(afap->af_name)-1] = '\0'; 258 afap->af_arg[sizeof(afap->af_arg)-1] = '\0'; 259 if (error) { 260 free(afap, M_TEMP); 261 return (error); 262 } 263 afp = accept_filt_get(afap->af_name); 264 if (afp == NULL) { 265 free(afap, M_TEMP); 266 return (ENOENT); 267 } 268 if (afp->accf_create != NULL && afap->af_name[0] != '\0') { 269 size_t len = strlen(afap->af_name) + 1; 270 accept_filter_str = malloc(len, M_ACCF, M_WAITOK); 271 strcpy(accept_filter_str, afap->af_name); 272 } 273 274 /* 275 * Require a listen socket; don't try to replace an existing filter 276 * without first removing it. 277 */ 278 SOCK_LOCK(so); 279 if (!SOLISTENING(so) || so->sol_accept_filter != NULL) { 280 error = EINVAL; 281 goto out; 282 } 283 284 /* 285 * Invoke the accf_create() method of the filter if required. The 286 * socket mutex is held over this call, so create methods for filters 287 * can't block. 288 */ 289 if (afp->accf_create != NULL) { 290 accept_filter_arg = afp->accf_create(so, afap->af_arg); 291 if (accept_filter_arg == NULL) { 292 error = EINVAL; 293 goto out; 294 } 295 } 296 so->sol_accept_filter = afp; 297 so->sol_accept_filter_arg = accept_filter_arg; 298 so->sol_accept_filter_str = accept_filter_str; 299 accept_filter_str = NULL; 300 so->so_options |= SO_ACCEPTFILTER; 301 out: 302 SOCK_UNLOCK(so); 303 if (accept_filter_str != NULL) 304 free(accept_filter_str, M_ACCF); 305 free(afap, M_TEMP); 306 return (error); 307 } 308