bsd/kern/kpi_socketfilter.c

   1 /*
   2  * Copyright (c) 2003-2007 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #include <sys/kpi_socketfilter.h>
  30
  31 #include <sys/socket.h>
  32 #include <sys/param.h>
  33 #include <sys/errno.h>
  34 #include <sys/malloc.h>
  35 #include <sys/protosw.h>
  36 #include <kern/locks.h>
  37 #include <net/kext_net.h>
  38
  39 #include <string.h>
  40
  41 static struct socket_filter_list        sock_filter_head;
  42 static lck_mtx_t                                        *sock_filter_lock = 0;
  43
  44 static void     sflt_detach_private(struct socket_filter_entry *entry, int unregistering);
  45
  46 __private_extern__ void
  47 sflt_init(void)
  48 {
  49         lck_grp_attr_t  *grp_attrib = 0;
  50         lck_attr_t              *lck_attrib = 0;
  51         lck_grp_t               *lck_group = 0;
  52
  53         TAILQ_INIT(&sock_filter_head);
  54
  55         /* Allocate a spin lock */
  56         grp_attrib = lck_grp_attr_alloc_init();
  57         lck_group = lck_grp_alloc_init("socket filter lock", grp_attrib);
  58         lck_grp_attr_free(grp_attrib);
  59         lck_attrib = lck_attr_alloc_init();
  60         sock_filter_lock = lck_mtx_alloc_init(lck_group, lck_attrib);
  61         lck_grp_free(lck_group);
  62         lck_attr_free(lck_attrib);
  63 }
  64
  65 __private_extern__ void
  66 sflt_initsock(
  67         struct socket *so)
  68 {
  69         struct protosw *proto = so->so_proto;
  70         struct socket_filter *filter;
  71
  72         if (TAILQ_FIRST(&proto->pr_filter_head) != NULL) {
  73                 lck_mtx_lock(sock_filter_lock);
  74                 TAILQ_FOREACH(filter, &proto->pr_filter_head, sf_protosw_next) {
  75                         sflt_attach_private(so, filter, 0, 0);
  76                 }
  77                 lck_mtx_unlock(sock_filter_lock);
  78         }
  79 }
  80
  81 __private_extern__ void
  82 sflt_termsock(
  83         struct socket *so)
  84 {
  85         struct socket_filter_entry *filter;
  86         struct socket_filter_entry *filter_next;
  87
  88         for (filter = so->so_filt; filter; filter = filter_next) {
  89                 filter_next = filter->sfe_next_onsocket;
  90                 sflt_detach_private(filter, 0);
  91         }
  92         so->so_filt = NULL;
  93 }
  94
  95 __private_extern__ void
  96 sflt_use(
  97         struct socket *so)
  98 {
  99         so->so_filteruse++;
 100 }
 101
 102 __private_extern__ void
 103 sflt_unuse(
 104         struct socket *so)
 105 {
 106         so->so_filteruse--;
 107         if (so->so_filteruse == 0) {
 108                 struct socket_filter_entry *filter;
 109                 struct socket_filter_entry *next_filter;
 110                 // search for detaching filters
 111                 for (filter = so->so_filt; filter; filter = next_filter) {
 112                         next_filter = filter->sfe_next_onsocket;
 113
 114                         if (filter->sfe_flags & SFEF_DETACHUSEZERO) {
 115                                 sflt_detach_private(filter, 0);
 116                         }
 117                 }
 118         }
 119 }
 120
 121 __private_extern__ void
 122 sflt_notify(
 123         struct socket   *so,
 124         sflt_event_t    event,
 125         void                    *param)
 126 {
 127         struct socket_filter_entry      *filter;
 128         int                                                     filtered = 0;
 129
 130         for (filter = so->so_filt; filter;
 131                  filter = filter->sfe_next_onsocket) {
 132                 if (filter->sfe_filter->sf_filter.sf_notify) {
 133                         if (filtered == 0) {
 134                                 filtered = 1;
 135                                 sflt_use(so);
 136                                 socket_unlock(so, 0);
 137                         }
 138                         filter->sfe_filter->sf_filter.sf_notify(
 139                                 filter->sfe_cookie, so, event, param);
 140                 }
 141         }
 142
 143         if (filtered != 0) {
 144                 socket_lock(so, 0);
 145                 sflt_unuse(so);
 146         }
 147 }
 148
 149 __private_extern__ int
 150 sflt_data_in(
 151         struct socket                   *so,
 152         const struct sockaddr   *from,
 153         mbuf_t                                  *data,
 154         mbuf_t                                  *control,
 155         sflt_data_flag_t                flags,
 156         int                                             *filtered)
 157 {
 158         struct socket_filter_entry      *filter;
 159         int                                                     error = 0;
 160         int                                                     filtered_storage;
 161
 162         if (filtered == NULL)
 163                 filtered = &filtered_storage;
 164         *filtered = 0;
 165
 166         for (filter = so->so_filt; filter && (error == 0);
 167                  filter = filter->sfe_next_onsocket) {
 168                 if (filter->sfe_filter->sf_filter.sf_data_in) {
 169                         if (*filtered == 0) {
 170                                 *filtered = 1;
 171                                 sflt_use(so);
 172                                 socket_unlock(so, 0);
 173                         }
 174                         error = filter->sfe_filter->sf_filter.sf_data_in(
 175                                                 filter->sfe_cookie, so, from, data, control, flags);
 176                 }
 177         }
 178
 179         if (*filtered != 0) {
 180                 socket_lock(so, 0);
 181                 sflt_unuse(so);
 182         }
 183
 184         return error;
 185 }
 186
 187 /* sflt_attach_private
 188  *
 189  * Assumptions: If filter is not NULL, socket_filter_lock is held.
 190  */
 191
 192 __private_extern__ int
 193 sflt_attach_private(
 194         struct socket *so,
 195         struct socket_filter *filter,
 196         sflt_handle                     handle,
 197         int sock_locked)
 198 {
 199         struct socket_filter_entry *entry = NULL;
 200         int didlock = 0;
 201         int error = 0;
 202
 203         if (filter == NULL) {
 204                 /* Find the filter by the handle */
 205                 lck_mtx_lock(sock_filter_lock);
 206                 didlock = 1;
 207
 208                 TAILQ_FOREACH(filter, &sock_filter_head, sf_global_next) {
 209                         if (filter->sf_filter.sf_handle == handle)
 210                                 break;
 211                 }
 212         }
 213
 214         if (filter == NULL)
 215                 error = ENOENT;
 216
 217         if (error == 0) {
 218                 /* allocate the socket filter entry */
 219                 MALLOC(entry, struct socket_filter_entry *, sizeof(*entry), M_IFADDR, M_WAITOK);
 220                 if (entry == NULL) {
 221                         error = ENOMEM;
 222                 }
 223         }
 224
 225         if (error == 0) {
 226                 /* Initialize the socket filter entry and call the attach function */
 227                 entry->sfe_filter = filter;
 228                 entry->sfe_socket = so;
 229                 entry->sfe_cookie = NULL;
 230                 entry->sfe_flags = 0;
 231                 if (entry->sfe_filter->sf_filter.sf_attach) {
 232                         filter->sf_usecount++;
 233
 234                         if (sock_locked)
 235                                 socket_unlock(so, 0);
 236                         error = entry->sfe_filter->sf_filter.sf_attach(&entry->sfe_cookie, so);
 237                         if (sock_locked)
 238                                 socket_lock(so, 0);
 239
 240                         filter->sf_usecount--;
 241
 242                         /* If the attach function returns an error, this filter is not attached */
 243                         if (error) {
 244                                 FREE(entry, M_IFADDR);
 245                                 entry = NULL;
 246                         }
 247                 }
 248         }
 249
 250         if (error == 0) {
 251                 /* Put the entry in the socket list */
 252                 entry->sfe_next_onsocket = so->so_filt;
 253                 so->so_filt = entry;
 254
 255                 /* Put the entry in the filter list */
 256                 entry->sfe_next_onfilter = filter->sf_entry_head;
 257                 filter->sf_entry_head = entry;
 258
 259                 /* Incremenet the parent filter's usecount */
 260                 filter->sf_usecount++;
 261         }
 262
 263         if (didlock) {
 264                 lck_mtx_unlock(sock_filter_lock);
 265         }
 266
 267         return error;
 268 }
 269
 270
 271 /* sflt_detach_private
 272  *
 273  * Assumptions: if you pass 0 in for the second parameter, you are holding the
 274  * socket lock for the socket the entry is attached to. If you pass 1 in for
 275  * the second parameter, it is assumed that the entry is not on the filter's
 276  * list and the socket lock is not held.
 277  */
 278
 279 static void
 280 sflt_detach_private(
 281         struct socket_filter_entry *entry,
 282         int     unregistering)
 283 {
 284         struct socket_filter_entry **next_ptr;
 285         int                             detached = 0;
 286         int                             found = 0;
 287
 288         if (unregistering) {
 289                 socket_lock(entry->sfe_socket, 0);
 290         }
 291
 292         /*
 293          * Attempt to find the entry on the filter's list and
 294          * remove it. This prevents a filter detaching at the
 295          * same time from attempting to remove the same entry.
 296          */
 297         lck_mtx_lock(sock_filter_lock);
 298         if (!unregistering) {
 299                 if ((entry->sfe_flags & SFEF_UNREGISTERING) != 0) {
 300                         /*
 301                          * Another thread is unregistering the filter, we need to
 302                          * avoid detaching the filter here so the socket won't go
 303                          * away.
 304                          */
 305                         lck_mtx_unlock(sock_filter_lock);
 306                         return;
 307                 }
 308                 for (next_ptr = &entry->sfe_filter->sf_entry_head; *next_ptr;
 309                          next_ptr = &((*next_ptr)->sfe_next_onfilter)) {
 310                         if (*next_ptr == entry) {
 311                                 found = 1;
 312                                 *next_ptr = entry->sfe_next_onfilter;
 313                                 break;
 314                         }
 315                 }
 316
 317                 if (!found && (entry->sfe_flags & SFEF_DETACHUSEZERO) == 0) {
 318                         lck_mtx_unlock(sock_filter_lock);
 319                         return;
 320                 }
 321         }
 322         else {
 323                 /*
 324                  * Clear the removing flag. We will perform the detach here or
 325                  * request a delayed deatch.
 326                  */
 327                 entry->sfe_flags &= ~SFEF_UNREGISTERING;
 328         }
 329
 330         if (entry->sfe_socket->so_filteruse != 0) {
 331                 entry->sfe_flags |= SFEF_DETACHUSEZERO;
 332                 lck_mtx_unlock(sock_filter_lock);
 333                 return;
 334         }
 335         else {
 336                 /*
 337                  * Check if we are removing the last attached filter and
 338                  * the parent filter is being unregistered.
 339                  */
 340                 entry->sfe_filter->sf_usecount--;
 341                 if ((entry->sfe_filter->sf_usecount == 0) &&
 342                         (entry->sfe_filter->sf_flags & SFF_DETACHING) != 0)
 343                         detached = 1;
 344         }
 345         lck_mtx_unlock(sock_filter_lock);
 346
 347         /* Remove from the socket list */
 348         for (next_ptr = &entry->sfe_socket->so_filt; *next_ptr;
 349                  next_ptr = &((*next_ptr)->sfe_next_onsocket)) {
 350                 if (*next_ptr == entry) {
 351                         *next_ptr = entry->sfe_next_onsocket;
 352                         break;
 353                 }
 354         }
 355
 356         if (entry->sfe_filter->sf_filter.sf_detach)
 357                 entry->sfe_filter->sf_filter.sf_detach(entry->sfe_cookie, entry->sfe_socket);
 358
 359         if (detached && entry->sfe_filter->sf_filter.sf_unregistered) {
 360                 entry->sfe_filter->sf_filter.sf_unregistered(entry->sfe_filter->sf_filter.sf_handle);
 361                 FREE(entry->sfe_filter, M_IFADDR);
 362         }
 363
 364         if (unregistering)
 365                 socket_unlock(entry->sfe_socket, 1);
 366
 367         FREE(entry, M_IFADDR);
 368 }
 369
 370 errno_t
 371 sflt_attach(
 372         socket_t        socket,
 373         sflt_handle     handle)
 374 {
 375         if (socket == NULL || handle == 0)
 376                 return EINVAL;
 377
 378         return sflt_attach_private(socket, NULL, handle, 0);
 379 }
 380
 381 errno_t
 382 sflt_detach(
 383         socket_t        socket,
 384         sflt_handle     handle)
 385 {
 386         struct socket_filter_entry      *filter;
 387         errno_t result = 0;
 388
 389         if (socket == NULL || handle == 0)
 390                 return EINVAL;
 391
 392         socket_lock(socket, 1);
 393
 394         for (filter = socket->so_filt; filter;
 395                  filter = filter->sfe_next_onsocket) {
 396                 if (filter->sfe_filter->sf_filter.sf_handle == handle)
 397                         break;
 398         }
 399
 400         if (filter != NULL) {
 401                 sflt_detach_private(filter, 0);
 402         }
 403         else {
 404                 socket->so_filt = NULL;
 405                 result = ENOENT;
 406         }
 407
 408         socket_unlock(socket, 1);
 409
 410         return result;
 411 }
 412
 413
 414 errno_t
 415 sflt_register(
 416         const struct sflt_filter        *filter,
 417         int                             domain,
 418         int                             type,
 419         int                             protocol)
 420 {
 421         struct socket_filter *sock_filt = NULL;
 422         struct socket_filter *match = NULL;
 423         int error = 0;
 424         struct protosw *pr = pffindproto(domain, protocol, type);
 425         unsigned int len;
 426
 427         if (pr == NULL)
 428                 return ENOENT;
 429
 430         if (filter->sf_attach == NULL || filter->sf_detach == NULL ||
 431             filter->sf_handle == 0 || filter->sf_name == NULL)
 432                 return EINVAL;
 433
 434         /* Allocate the socket filter */
 435         MALLOC(sock_filt, struct socket_filter *, sizeof (*sock_filt),
 436             M_IFADDR, M_WAITOK);
 437         if (sock_filt == NULL) {
 438                 return ENOBUFS;
 439         }
 440
 441         bzero(sock_filt, sizeof (*sock_filt));
 442
 443         /* Legacy sflt_filter length; current structure minus extended */
 444         len = sizeof (*filter) - sizeof (struct sflt_filter_ext);
 445         /*
 446          * Include extended fields if filter defines SFLT_EXTENDED.
 447          * We've zeroed out our internal sflt_filter placeholder,
 448          * so any unused portion would have been taken care of.
 449          */
 450         if (filter->sf_flags & SFLT_EXTENDED) {
 451                 unsigned int ext_len = filter->sf_len;
 452
 453                 if (ext_len > sizeof (struct sflt_filter_ext))
 454                         ext_len = sizeof (struct sflt_filter_ext);
 455
 456                 len += ext_len;
 457         }
 458         bcopy(filter, &sock_filt->sf_filter, len);
 459
 460         lck_mtx_lock(sock_filter_lock);
 461         /* Look for an existing entry */
 462         TAILQ_FOREACH(match, &sock_filter_head, sf_global_next) {
 463                 if (match->sf_filter.sf_handle ==
 464                     sock_filt->sf_filter.sf_handle) {
 465                         break;
 466                 }
 467         }
 468
 469         /* Add the entry only if there was no existing entry */
 470         if (match == NULL) {
 471                 TAILQ_INSERT_TAIL(&sock_filter_head, sock_filt, sf_global_next);
 472                 if ((sock_filt->sf_filter.sf_flags & SFLT_GLOBAL) != 0) {
 473                         TAILQ_INSERT_TAIL(&pr->pr_filter_head, sock_filt,
 474                             sf_protosw_next);
 475                         sock_filt->sf_proto = pr;
 476                 }
 477         }
 478         lck_mtx_unlock(sock_filter_lock);
 479
 480         if (match != NULL) {
 481                 FREE(sock_filt, M_IFADDR);
 482                 return EEXIST;
 483         }
 484
 485         return error;
 486 }
 487
 488 errno_t
 489 sflt_unregister(
 490         sflt_handle handle)
 491 {
 492         struct socket_filter *filter;
 493         struct socket_filter_entry *entry_head = NULL;
 494         struct socket_filter_entry *next_entry = NULL;
 495
 496         /* Find the entry and remove it from the global and protosw lists */
 497         lck_mtx_lock(sock_filter_lock);
 498         TAILQ_FOREACH(filter, &sock_filter_head, sf_global_next) {
 499                 if (filter->sf_filter.sf_handle == handle)
 500                         break;
 501         }
 502
 503         if (filter) {
 504                 TAILQ_REMOVE(&sock_filter_head, filter, sf_global_next);
 505                 if ((filter->sf_filter.sf_flags & SFLT_GLOBAL) != 0) {
 506                         TAILQ_REMOVE(&filter->sf_proto->pr_filter_head, filter, sf_protosw_next);
 507                 }
 508                 entry_head = filter->sf_entry_head;
 509                 filter->sf_entry_head = NULL;
 510                 filter->sf_flags |= SFF_DETACHING;
 511
 512                 for (next_entry = entry_head; next_entry;
 513                          next_entry = next_entry->sfe_next_onfilter) {
 514                         socket_lock(next_entry->sfe_socket, 1);
 515                         next_entry->sfe_flags |= SFEF_UNREGISTERING;
 516                         socket_unlock(next_entry->sfe_socket, 0);       /* Radar 4201550: prevents the socket from being deleted while being unregistered */
 517                 }
 518         }
 519
 520         lck_mtx_unlock(sock_filter_lock);
 521
 522         if (filter == NULL)
 523                 return ENOENT;
 524
 525         /* We need to detach the filter from any sockets it's attached to */
 526         if (entry_head == 0) {
 527                 if (filter->sf_filter.sf_unregistered)
 528                         filter->sf_filter.sf_unregistered(filter->sf_filter.sf_handle);
 529         } else {
 530                 while (entry_head) {
 531                         next_entry = entry_head->sfe_next_onfilter;
 532                         sflt_detach_private(entry_head, 1);
 533                         entry_head = next_entry;
 534                 }
 535         }
 536
 537         return 0;
 538 }
 539
 540 errno_t
 541 sock_inject_data_in(
 542         socket_t so,
 543         const struct sockaddr* from,
 544         mbuf_t data,
 545         mbuf_t control,
 546         sflt_data_flag_t flags)
 547 {
 548         int error = 0;
 549         if (so == NULL || data == NULL) return EINVAL;
 550
 551         if (flags & sock_data_filt_flag_oob) {
 552                 return ENOTSUP;
 553         }
 554
 555         socket_lock(so, 1);
 556
 557         if (from) {
 558                 if (sbappendaddr(&so->so_rcv, (struct sockaddr*)from, data,
 559                                                  control, NULL))
 560                         sorwakeup(so);
 561                 goto done;
 562         }
 563
 564         if (control) {
 565                 if (sbappendcontrol(&so->so_rcv, data, control, NULL))
 566                         sorwakeup(so);
 567                 goto done;
 568         }
 569
 570         if (flags & sock_data_filt_flag_record) {
 571                 if (control || from) {
 572                         error = EINVAL;
 573                         goto done;
 574                 }
 575                 if (sbappendrecord(&so->so_rcv, (struct mbuf*)data))
 576                         sorwakeup(so);
 577                 goto done;
 578         }
 579
 580         if (sbappend(&so->so_rcv, data))
 581                 sorwakeup(so);
 582 done:
 583         socket_unlock(so, 1);
 584         return error;
 585 }
 586
 587 errno_t
 588 sock_inject_data_out(
 589         socket_t so,
 590         const struct sockaddr* to,
 591         mbuf_t data,
 592         mbuf_t control,
 593         sflt_data_flag_t flags)
 594 {
 595         int     sosendflags = 0;
 596         if (flags & sock_data_filt_flag_oob) sosendflags = MSG_OOB;
 597         return sosend(so, (struct sockaddr*)to, NULL,
 598                                   data, control, sosendflags);
 599 }
 600
 601 sockopt_dir
 602 sockopt_direction(
 603         sockopt_t       sopt)
 604 {
 605         return (sopt->sopt_dir == SOPT_GET) ? sockopt_get : sockopt_set;
 606 }
 607
 608 int
 609 sockopt_level(
 610         sockopt_t       sopt)
 611 {
 612         return sopt->sopt_level;
 613 }
 614
 615 int
 616 sockopt_name(
 617         sockopt_t       sopt)
 618 {
 619         return sopt->sopt_name;
 620 }
 621
 622 size_t
 623 sockopt_valsize(
 624         sockopt_t       sopt)
 625 {
 626         return sopt->sopt_valsize;
 627 }
 628
 629 errno_t
 630 sockopt_copyin(
 631         sockopt_t       sopt,
 632         void *data,
 633         size_t  len)
 634 {
 635         return sooptcopyin(sopt, data, len, len);
 636 }
 637
 638 errno_t
 639 sockopt_copyout(
 640         sockopt_t       sopt,
 641         void *data,
 642         size_t  len)
 643 {
 644         return sooptcopyout(sopt, data, len);
 645 }