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, M_WAITOK); 134 bcopy(accfp, p, sizeof(*p)); 135 error = accept_filt_add(p); 136 break; 137 138 case MOD_UNLOAD: 139 /* 140 * Do not support unloading yet. we don't keep track of 141 * refcounts and unloading an accept filter callback and then 142 * having it called is a bad thing. A simple fix would be to 143 * track the refcount in the struct accept_filter. 144 */ 145 if (unloadable != 0) { 146 error = accept_filt_del(accfp->accf_name); 147 } else 148 error = EOPNOTSUPP; 149 break; 150 151 case MOD_SHUTDOWN: 152 error = 0; 153 break; 154 155 default: 156 error = EOPNOTSUPP; 157 break; 158 } 159 160 return (error); 161 } 162 163 int 164 accept_filt_getopt(struct socket *so, struct sockopt *sopt) 165 { 166 struct accept_filter_arg *afap; 167 int error; 168 169 error = 0; 170 afap = malloc(sizeof(*afap), M_TEMP, M_WAITOK | M_ZERO); 171 SOCK_LOCK(so); 172 if ((so->so_options & SO_ACCEPTCONN) == 0) { 173 error = EINVAL; 174 goto out; 175 } 176 if (so->sol_accept_filter == NULL) { 177 error = EINVAL; 178 goto out; 179 } 180 strcpy(afap->af_name, so->sol_accept_filter->accf_name); 181 if (so->sol_accept_filter_str != NULL) 182 strcpy(afap->af_arg, so->sol_accept_filter_str); 183 out: 184 SOCK_UNLOCK(so); 185 if (error == 0) 186 error = sooptcopyout(sopt, afap, sizeof(*afap)); 187 free(afap, M_TEMP); 188 return (error); 189 } 190 191 int 192 accept_filt_setopt(struct socket *so, struct sockopt *sopt) 193 { 194 struct accept_filter_arg *afap; 195 struct accept_filter *afp; 196 char *accept_filter_str = NULL; 197 void *accept_filter_arg = NULL; 198 int error; 199 200 /* 201 * Handle the simple delete case first. 202 */ 203 if (sopt == NULL || sopt->sopt_val == NULL) { 204 struct socket *sp, *sp1; 205 int wakeup; 206 207 SOCK_LOCK(so); 208 if ((so->so_options & SO_ACCEPTCONN) == 0) { 209 SOCK_UNLOCK(so); 210 return (EINVAL); 211 } 212 if (so->sol_accept_filter == NULL) { 213 SOCK_UNLOCK(so); 214 return (0); 215 } 216 if (so->sol_accept_filter->accf_destroy != NULL) 217 so->sol_accept_filter->accf_destroy(so); 218 if (so->sol_accept_filter_str != NULL) 219 free(so->sol_accept_filter_str, M_ACCF); 220 so->sol_accept_filter = NULL; 221 so->sol_accept_filter_arg = NULL; 222 so->sol_accept_filter_str = NULL; 223 so->so_options &= ~SO_ACCEPTFILTER; 224 225 /* 226 * Move from incomplete queue to complete only those 227 * connections, that are blocked by us. 228 */ 229 wakeup = 0; 230 TAILQ_FOREACH_SAFE(sp, &so->sol_incomp, so_list, sp1) { 231 SOCK_LOCK(sp); 232 if (sp->so_options & SO_ACCEPTFILTER) { 233 TAILQ_REMOVE(&so->sol_incomp, sp, so_list); 234 TAILQ_INSERT_TAIL(&so->sol_comp, sp, so_list); 235 sp->so_qstate = SQ_COMP; 236 sp->so_options &= ~SO_ACCEPTFILTER; 237 so->sol_incqlen--; 238 so->sol_qlen++; 239 wakeup = 1; 240 } 241 SOCK_UNLOCK(sp); 242 } 243 if (wakeup) 244 solisten_wakeup(so); /* unlocks */ 245 else 246 SOLISTEN_UNLOCK(so); 247 return (0); 248 } 249 250 /* 251 * Pre-allocate any memory we may need later to avoid blocking at 252 * untimely moments. This does not optimize for invalid arguments. 253 */ 254 afap = malloc(sizeof(*afap), M_TEMP, M_WAITOK); 255 error = sooptcopyin(sopt, afap, sizeof *afap, sizeof *afap); 256 afap->af_name[sizeof(afap->af_name)-1] = '\0'; 257 afap->af_arg[sizeof(afap->af_arg)-1] = '\0'; 258 if (error) { 259 free(afap, M_TEMP); 260 return (error); 261 } 262 afp = accept_filt_get(afap->af_name); 263 if (afp == NULL) { 264 free(afap, M_TEMP); 265 return (ENOENT); 266 } 267 if (afp->accf_create != NULL && afap->af_name[0] != '\0') { 268 size_t len = strlen(afap->af_name) + 1; 269 accept_filter_str = malloc(len, M_ACCF, M_WAITOK); 270 strcpy(accept_filter_str, afap->af_name); 271 } 272 273 /* 274 * Require a listen socket; don't try to replace an existing filter 275 * without first removing it. 276 */ 277 SOCK_LOCK(so); 278 if ((so->so_options & SO_ACCEPTCONN) == 0 || 279 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 so->so_options |= SO_ACCEPTFILTER; 300 out: 301 SOCK_UNLOCK(so); 302 if (accept_filter_str != NULL) 303 free(accept_filter_str, M_ACCF); 304 free(afap, M_TEMP); 305 return (error); 306 } 307