1 /*- 2 * Copyright (c) 2010-2012 The NetBSD Foundation, Inc. 3 * All rights reserved. 4 * 5 * This material is based upon work partially supported by The 6 * NetBSD Foundation under a contract with Mindaugas Rasiukevicius. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 18 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 19 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 20 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 21 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 22 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 24 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 25 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 26 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 27 * POSSIBILITY OF SUCH DAMAGE. 28 */ 29 30 /* 31 * NPF TCP state engine for connection tracking. 32 */ 33 34 #ifdef _KERNEL 35 #include <sys/cdefs.h> 36 __KERNEL_RCSID(0, "$NetBSD: npf_state_tcp.c,v 1.20 2019/07/23 00:52:01 rmind Exp $"); 37 38 #include <sys/param.h> 39 #include <sys/types.h> 40 41 #include <netinet/in.h> 42 #include <netinet/tcp.h> 43 #endif 44 45 #include "npf_impl.h" 46 47 /* 48 * NPF TCP states. Note: these states are different from the TCP FSM 49 * states of RFC 793. The packet filter is a man-in-the-middle. 50 */ 51 #define NPF_TCPS_OK 255 52 #define NPF_TCPS_CLOSED 0 53 #define NPF_TCPS_SYN_SENT 1 54 #define NPF_TCPS_SIMSYN_SENT 2 55 #define NPF_TCPS_SYN_RECEIVED 3 56 #define NPF_TCPS_ESTABLISHED 4 57 #define NPF_TCPS_FIN_SENT 5 58 #define NPF_TCPS_FIN_RECEIVED 6 59 #define NPF_TCPS_CLOSE_WAIT 7 60 #define NPF_TCPS_FIN_WAIT 8 61 #define NPF_TCPS_CLOSING 9 62 #define NPF_TCPS_LAST_ACK 10 63 #define NPF_TCPS_TIME_WAIT 11 64 65 #define NPF_TCP_NSTATES 12 66 67 /* Timeouts */ 68 #define NPF_TCPT_NEW 0 69 #define NPF_TCPT_ESTABLISHED 1 70 #define NPF_TCPT_HALFCLOSE 2 71 #define NPF_TCPT_CLOSE 3 72 #define NPF_TCPT_TIMEWAIT 4 73 #define NPF_TCPT_COUNT 5 74 75 /* 76 * Parameters. 77 */ 78 typedef struct { 79 int max_ack_win; 80 int strict_order_rst; 81 int timeouts[NPF_TCPT_COUNT]; 82 } npf_state_tcp_params_t; 83 84 /* 85 * Helpers. 86 */ 87 #define SEQ_LT(a,b) ((int)((a)-(b)) < 0) 88 #define SEQ_LEQ(a,b) ((int)((a)-(b)) <= 0) 89 #define SEQ_GT(a,b) ((int)((a)-(b)) > 0) 90 #define SEQ_GEQ(a,b) ((int)((a)-(b)) >= 0) 91 92 /* 93 * List of TCP flag cases and conversion of flags to a case (index). 94 */ 95 96 #define TCPFC_INVALID 0 97 #define TCPFC_SYN 1 98 #define TCPFC_SYNACK 2 99 #define TCPFC_ACK 3 100 #define TCPFC_FIN 4 101 #define TCPFC_COUNT 5 102 103 static inline unsigned 104 npf_tcpfl2case(const unsigned tcpfl) 105 { 106 unsigned i, c; 107 108 CTASSERT(TH_FIN == 0x01); 109 CTASSERT(TH_SYN == 0x02); 110 CTASSERT(TH_ACK == 0x10); 111 112 /* 113 * Flags are shifted to use three least significant bits, thus each 114 * flag combination has a unique number ranging from 0 to 7, e.g. 115 * TH_SYN | TH_ACK has number 6, since (0x02 | (0x10 >> 2)) == 6. 116 * However, the requirement is to have number 0 for invalid cases, 117 * such as TH_SYN | TH_FIN, and to have the same number for TH_FIN 118 * and TH_FIN|TH_ACK cases. Thus, we generate a mask assigning 3 119 * bits for each number, which contains the actual case numbers: 120 * 121 * TCPFC_SYNACK << (6 << 2) == 0x2000000 (6 - SYN,ACK) 122 * TCPFC_FIN << (5 << 2) == 0x0400000 (5 - FIN,ACK) 123 * ... 124 * 125 * Hence, OR'ed mask value is 0x2430140. 126 */ 127 i = (tcpfl & (TH_SYN | TH_FIN)) | ((tcpfl & TH_ACK) >> 2); 128 c = (0x2430140 >> (i << 2)) & 7; 129 130 KASSERT(c < TCPFC_COUNT); 131 return c; 132 } 133 134 /* 135 * NPF transition table of a tracked TCP connection. 136 * 137 * There is a single state, which is changed in the following way: 138 * 139 * new_state = npf_tcp_fsm[old_state][direction][npf_tcpfl2case(tcp_flags)]; 140 * 141 * Note that this state is different from the state in each end (host). 142 */ 143 144 static const uint8_t npf_tcp_fsm[NPF_TCP_NSTATES][2][TCPFC_COUNT] = { 145 [NPF_TCPS_CLOSED] = { 146 [NPF_FLOW_FORW] = { 147 /* Handshake (1): initial SYN. */ 148 [TCPFC_SYN] = NPF_TCPS_SYN_SENT, 149 }, 150 }, 151 [NPF_TCPS_SYN_SENT] = { 152 [NPF_FLOW_FORW] = { 153 /* SYN may be retransmitted. */ 154 [TCPFC_SYN] = NPF_TCPS_OK, 155 }, 156 [NPF_FLOW_BACK] = { 157 /* Handshake (2): SYN-ACK is expected. */ 158 [TCPFC_SYNACK] = NPF_TCPS_SYN_RECEIVED, 159 /* Simultaneous initiation - SYN. */ 160 [TCPFC_SYN] = NPF_TCPS_SIMSYN_SENT, 161 }, 162 }, 163 [NPF_TCPS_SIMSYN_SENT] = { 164 [NPF_FLOW_FORW] = { 165 /* Original SYN re-transmission. */ 166 [TCPFC_SYN] = NPF_TCPS_OK, 167 /* SYN-ACK response to simultaneous SYN. */ 168 [TCPFC_SYNACK] = NPF_TCPS_SYN_RECEIVED, 169 }, 170 [NPF_FLOW_BACK] = { 171 /* Simultaneous SYN re-transmission.*/ 172 [TCPFC_SYN] = NPF_TCPS_OK, 173 /* SYN-ACK response to original SYN. */ 174 [TCPFC_SYNACK] = NPF_TCPS_SYN_RECEIVED, 175 /* FIN may occur early. */ 176 [TCPFC_FIN] = NPF_TCPS_FIN_RECEIVED, 177 }, 178 }, 179 [NPF_TCPS_SYN_RECEIVED] = { 180 [NPF_FLOW_FORW] = { 181 /* Handshake (3): ACK is expected. */ 182 [TCPFC_ACK] = NPF_TCPS_ESTABLISHED, 183 /* FIN may be sent early. */ 184 [TCPFC_FIN] = NPF_TCPS_FIN_SENT, 185 /* Late SYN re-transmission. */ 186 [TCPFC_SYN] = NPF_TCPS_OK, 187 }, 188 [NPF_FLOW_BACK] = { 189 /* SYN-ACK may be retransmitted. */ 190 [TCPFC_SYNACK] = NPF_TCPS_OK, 191 /* XXX: ACK of late SYN in simultaneous case? */ 192 [TCPFC_ACK] = NPF_TCPS_OK, 193 /* FIN may occur early. */ 194 [TCPFC_FIN] = NPF_TCPS_FIN_RECEIVED, 195 }, 196 }, 197 [NPF_TCPS_ESTABLISHED] = { 198 /* 199 * Regular ACKs (data exchange) or FIN. 200 * FIN packets may have ACK set. 201 */ 202 [NPF_FLOW_FORW] = { 203 [TCPFC_ACK] = NPF_TCPS_OK, 204 /* FIN by the sender. */ 205 [TCPFC_FIN] = NPF_TCPS_FIN_SENT, 206 }, 207 [NPF_FLOW_BACK] = { 208 [TCPFC_ACK] = NPF_TCPS_OK, 209 /* FIN by the receiver. */ 210 [TCPFC_FIN] = NPF_TCPS_FIN_RECEIVED, 211 }, 212 }, 213 [NPF_TCPS_FIN_SENT] = { 214 [NPF_FLOW_FORW] = { 215 /* FIN may be re-transmitted. Late ACK as well. */ 216 [TCPFC_ACK] = NPF_TCPS_OK, 217 [TCPFC_FIN] = NPF_TCPS_OK, 218 }, 219 [NPF_FLOW_BACK] = { 220 /* If ACK, connection is half-closed now. */ 221 [TCPFC_ACK] = NPF_TCPS_FIN_WAIT, 222 /* FIN or FIN-ACK race - immediate closing. */ 223 [TCPFC_FIN] = NPF_TCPS_CLOSING, 224 }, 225 }, 226 [NPF_TCPS_FIN_RECEIVED] = { 227 /* 228 * FIN was received. Equivalent scenario to sent FIN. 229 */ 230 [NPF_FLOW_FORW] = { 231 [TCPFC_ACK] = NPF_TCPS_CLOSE_WAIT, 232 [TCPFC_FIN] = NPF_TCPS_CLOSING, 233 }, 234 [NPF_FLOW_BACK] = { 235 [TCPFC_ACK] = NPF_TCPS_OK, 236 [TCPFC_FIN] = NPF_TCPS_OK, 237 }, 238 }, 239 [NPF_TCPS_CLOSE_WAIT] = { 240 /* Sender has sent the FIN and closed its end. */ 241 [NPF_FLOW_FORW] = { 242 [TCPFC_ACK] = NPF_TCPS_OK, 243 [TCPFC_FIN] = NPF_TCPS_LAST_ACK, 244 }, 245 [NPF_FLOW_BACK] = { 246 [TCPFC_ACK] = NPF_TCPS_OK, 247 [TCPFC_FIN] = NPF_TCPS_LAST_ACK, 248 }, 249 }, 250 [NPF_TCPS_FIN_WAIT] = { 251 /* Receiver has closed its end. */ 252 [NPF_FLOW_FORW] = { 253 [TCPFC_ACK] = NPF_TCPS_OK, 254 [TCPFC_FIN] = NPF_TCPS_LAST_ACK, 255 }, 256 [NPF_FLOW_BACK] = { 257 [TCPFC_ACK] = NPF_TCPS_OK, 258 [TCPFC_FIN] = NPF_TCPS_LAST_ACK, 259 }, 260 }, 261 [NPF_TCPS_CLOSING] = { 262 /* Race of FINs - expecting ACK. */ 263 [NPF_FLOW_FORW] = { 264 [TCPFC_ACK] = NPF_TCPS_LAST_ACK, 265 }, 266 [NPF_FLOW_BACK] = { 267 [TCPFC_ACK] = NPF_TCPS_LAST_ACK, 268 }, 269 }, 270 [NPF_TCPS_LAST_ACK] = { 271 /* FINs exchanged - expecting last ACK. */ 272 [NPF_FLOW_FORW] = { 273 [TCPFC_ACK] = NPF_TCPS_TIME_WAIT, 274 }, 275 [NPF_FLOW_BACK] = { 276 [TCPFC_ACK] = NPF_TCPS_TIME_WAIT, 277 }, 278 }, 279 [NPF_TCPS_TIME_WAIT] = { 280 /* May re-open the connection as per RFC 1122. */ 281 [NPF_FLOW_FORW] = { 282 [TCPFC_SYN] = NPF_TCPS_SYN_SENT, 283 }, 284 }, 285 }; 286 287 /* 288 * npf_tcp_inwindow: determine whether the packet is in the TCP window 289 * and thus part of the connection we are tracking. 290 */ 291 static bool 292 npf_tcp_inwindow(npf_cache_t *npc, npf_state_t *nst, const int di) 293 { 294 const npf_state_tcp_params_t *params; 295 const struct tcphdr * const th = npc->npc_l4.tcp; 296 const int tcpfl = th->th_flags; 297 npf_tcpstate_t *fstate, *tstate; 298 int tcpdlen, ackskew; 299 tcp_seq seq, ack, end; 300 uint32_t win; 301 302 params = npc->npc_ctx->params[NPF_PARAMS_TCP_STATE]; 303 KASSERT(npf_iscached(npc, NPC_TCP)); 304 KASSERT(di == NPF_FLOW_FORW || di == NPF_FLOW_BACK); 305 306 /* 307 * Perform SEQ/ACK numbers check against boundaries. Reference: 308 * 309 * Rooij G., "Real stateful TCP packet filtering in IP Filter", 310 * 10th USENIX Security Symposium invited talk, Aug. 2001. 311 * 312 * There are four boundaries defined as following: 313 * I) SEQ + LEN <= MAX { SND.ACK + MAX(SND.WIN, 1) } 314 * II) SEQ >= MAX { SND.SEQ + SND.LEN - MAX(RCV.WIN, 1) } 315 * III) ACK <= MAX { RCV.SEQ + RCV.LEN } 316 * IV) ACK >= MAX { RCV.SEQ + RCV.LEN } - MAXACKWIN 317 * 318 * Let these members of npf_tcpstate_t be the maximum seen values of: 319 * nst_end - SEQ + LEN 320 * nst_maxend - ACK + MAX(WIN, 1) 321 * nst_maxwin - MAX(WIN, 1) 322 */ 323 324 tcpdlen = npf_tcpsaw(__UNCONST(npc), &seq, &ack, &win); 325 end = seq + tcpdlen; 326 if (tcpfl & TH_SYN) { 327 end++; 328 } 329 if (tcpfl & TH_FIN) { 330 end++; 331 } 332 333 fstate = &nst->nst_tcpst[di]; 334 tstate = &nst->nst_tcpst[!di]; 335 win = win ? (win << fstate->nst_wscale) : 1; 336 337 /* 338 * Initialise if the first packet. 339 * Note: only case when nst_maxwin is zero. 340 */ 341 if (__predict_false(fstate->nst_maxwin == 0)) { 342 /* 343 * Normally, it should be the first SYN or a re-transmission 344 * of SYN. The state of the other side will get set with a 345 * SYN-ACK reply (see below). 346 */ 347 fstate->nst_end = end; 348 fstate->nst_maxend = end; 349 fstate->nst_maxwin = win; 350 tstate->nst_end = 0; 351 tstate->nst_maxend = 0; 352 tstate->nst_maxwin = 1; 353 354 /* 355 * Handle TCP Window Scaling (RFC 1323). Both sides may 356 * send this option in their SYN packets. 357 */ 358 fstate->nst_wscale = 0; 359 (void)npf_fetch_tcpopts(npc, NULL, &fstate->nst_wscale); 360 361 tstate->nst_wscale = 0; 362 363 /* Done. */ 364 return true; 365 } 366 367 if (fstate->nst_end == 0) { 368 /* 369 * Should be a SYN-ACK reply to SYN. If SYN is not set, 370 * then we are in the middle of connection and lost tracking. 371 */ 372 fstate->nst_end = end; 373 fstate->nst_maxend = end + 1; 374 fstate->nst_maxwin = win; 375 fstate->nst_wscale = 0; 376 377 /* Handle TCP Window Scaling (must be ignored if no SYN). */ 378 if (tcpfl & TH_SYN) { 379 (void)npf_fetch_tcpopts(npc, NULL, &fstate->nst_wscale); 380 } 381 } 382 383 if ((tcpfl & TH_ACK) == 0) { 384 /* Pretend that an ACK was sent. */ 385 ack = tstate->nst_end; 386 } else if ((tcpfl & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST) && ack == 0) { 387 /* Workaround for some TCP stacks. */ 388 ack = tstate->nst_end; 389 } 390 391 if (__predict_false(tcpfl & TH_RST)) { 392 /* RST to the initial SYN may have zero SEQ - fix it up. */ 393 if (seq == 0 && nst->nst_state == NPF_TCPS_SYN_SENT) { 394 end = fstate->nst_end; 395 seq = end; 396 } 397 398 /* Strict in-order sequence for RST packets (RFC 5961). */ 399 if (params->strict_order_rst && (fstate->nst_end - seq) > 1) { 400 return false; 401 } 402 } 403 404 /* 405 * Determine whether the data is within previously noted window, 406 * that is, upper boundary for valid data (I). 407 */ 408 if (!SEQ_LEQ(end, fstate->nst_maxend)) { 409 npf_stats_inc(npc->npc_ctx, NPF_STAT_INVALID_STATE_TCP1); 410 return false; 411 } 412 413 /* Lower boundary (II), which is no more than one window back. */ 414 if (!SEQ_GEQ(seq, fstate->nst_end - tstate->nst_maxwin)) { 415 npf_stats_inc(npc->npc_ctx, NPF_STAT_INVALID_STATE_TCP2); 416 return false; 417 } 418 419 /* 420 * Boundaries for valid acknowledgments (III, IV) - one predicted 421 * window up or down, since packets may be fragmented. 422 */ 423 ackskew = tstate->nst_end - ack; 424 if (ackskew < -(int)params->max_ack_win || 425 ackskew > ((int)params->max_ack_win << fstate->nst_wscale)) { 426 npf_stats_inc(npc->npc_ctx, NPF_STAT_INVALID_STATE_TCP3); 427 return false; 428 } 429 430 /* 431 * Packet has been passed. 432 * 433 * Negative ackskew might be due to fragmented packets. Since the 434 * total length of the packet is unknown - bump the boundary. 435 */ 436 437 if (ackskew < 0) { 438 tstate->nst_end = ack; 439 } 440 /* Keep track of the maximum window seen. */ 441 if (fstate->nst_maxwin < win) { 442 fstate->nst_maxwin = win; 443 } 444 if (SEQ_GT(end, fstate->nst_end)) { 445 fstate->nst_end = end; 446 } 447 /* Note the window for upper boundary. */ 448 if (SEQ_GEQ(ack + win, tstate->nst_maxend)) { 449 tstate->nst_maxend = ack + win; 450 } 451 return true; 452 } 453 454 /* 455 * npf_state_tcp: inspect TCP segment, determine whether it belongs to 456 * the connection and track its state. 457 */ 458 bool 459 npf_state_tcp(npf_cache_t *npc, npf_state_t *nst, int di) 460 { 461 const struct tcphdr * const th = npc->npc_l4.tcp; 462 const unsigned tcpfl = th->th_flags, state = nst->nst_state; 463 unsigned nstate; 464 465 KASSERT(nst->nst_state < NPF_TCP_NSTATES); 466 467 /* Look for a transition to a new state. */ 468 if (__predict_true((tcpfl & TH_RST) == 0)) { 469 const u_int flagcase = npf_tcpfl2case(tcpfl); 470 nstate = npf_tcp_fsm[state][di][flagcase]; 471 } else if (state == NPF_TCPS_TIME_WAIT) { 472 /* Prevent TIME-WAIT assassination (RFC 1337). */ 473 nstate = NPF_TCPS_OK; 474 } else { 475 nstate = NPF_TCPS_CLOSED; 476 } 477 478 /* Determine whether TCP packet really belongs to this connection. */ 479 if (!npf_tcp_inwindow(npc, nst, di)) { 480 return false; 481 } 482 if (__predict_true(nstate == NPF_TCPS_OK)) { 483 return true; 484 } 485 486 nst->nst_state = nstate; 487 return true; 488 } 489 490 int 491 npf_state_tcp_timeout(npf_t *npf, const npf_state_t *nst) 492 { 493 static const uint8_t state_timeout_idx[NPF_TCP_NSTATES] = { 494 [NPF_TCPS_CLOSED] = NPF_TCPT_CLOSE, 495 /* Unsynchronised states. */ 496 [NPF_TCPS_SYN_SENT] = NPF_TCPT_NEW, 497 [NPF_TCPS_SIMSYN_SENT] = NPF_TCPT_NEW, 498 [NPF_TCPS_SYN_RECEIVED] = NPF_TCPT_NEW, 499 /* Established (synchronised state). */ 500 [NPF_TCPS_ESTABLISHED] = NPF_TCPT_ESTABLISHED, 501 /* Half-closed cases. */ 502 [NPF_TCPS_FIN_SENT] = NPF_TCPT_HALFCLOSE, 503 [NPF_TCPS_FIN_RECEIVED] = NPF_TCPT_HALFCLOSE, 504 [NPF_TCPS_CLOSE_WAIT] = NPF_TCPT_HALFCLOSE, 505 [NPF_TCPS_FIN_WAIT] = NPF_TCPT_HALFCLOSE, 506 /* Full close cases. */ 507 [NPF_TCPS_CLOSING] = NPF_TCPT_CLOSE, 508 [NPF_TCPS_LAST_ACK] = NPF_TCPT_CLOSE, 509 [NPF_TCPS_TIME_WAIT] = NPF_TCPT_TIMEWAIT, 510 }; 511 const npf_state_tcp_params_t *params; 512 const unsigned state = nst->nst_state; 513 514 KASSERT(state < NPF_TCP_NSTATES); 515 params = npf->params[NPF_PARAMS_TCP_STATE]; 516 return params->timeouts[state_timeout_idx[state]]; 517 } 518 519 void 520 npf_state_tcp_sysinit(npf_t *npf) 521 { 522 npf_state_tcp_params_t *params = npf_param_allocgroup(npf, 523 NPF_PARAMS_TCP_STATE, sizeof(npf_state_tcp_params_t)); 524 npf_param_t param_map[] = { 525 /* 526 * TCP connection timeout table (in seconds). 527 */ 528 529 /* Unsynchronised states. */ 530 { 531 "state.tcp.timeout.new", 532 ¶ms->timeouts[NPF_TCPT_NEW], 533 .default_val = 30, 534 .min = 0, .max = INT_MAX 535 }, 536 /* Established. */ 537 { 538 "state.tcp.timeout.established", 539 ¶ms->timeouts[NPF_TCPT_ESTABLISHED], 540 .default_val = 60 * 60 * 24, 541 .min = 0, .max = INT_MAX 542 }, 543 /* Half-closed cases. */ 544 { 545 "state.tcp.timeout.half_close", 546 ¶ms->timeouts[NPF_TCPT_HALFCLOSE], 547 .default_val = 60 * 60 * 6, 548 .min = 0, .max = INT_MAX 549 }, 550 /* Full close cases. */ 551 { 552 "state.tcp.timeout.close", 553 ¶ms->timeouts[NPF_TCPT_CLOSE], 554 .default_val = 10, 555 .min = 0, .max = INT_MAX 556 }, 557 /* TCP time-wait (2 * MSL). */ 558 { 559 "state.tcp.timeout.time_wait", 560 ¶ms->timeouts[NPF_TCPT_TIMEWAIT], 561 .default_val = 60 * 2 * 2, 562 .min = 0, .max = INT_MAX 563 }, 564 565 /* 566 * Enforce strict order RST. 567 */ 568 { 569 "state.tcp.strict_order_rst", 570 ¶ms->strict_order_rst, 571 .default_val = 1, // true 572 .min = 0, .max = 1 573 }, 574 575 /* 576 * TCP state tracking: maximum allowed ACK window. 577 */ 578 { 579 "state.tcp.max_ack_win", 580 ¶ms->max_ack_win, 581 .default_val = 66000, 582 .min = 0, .max = INT_MAX 583 }, 584 }; 585 npf_param_register(npf, param_map, __arraycount(param_map)); 586 } 587 588 void 589 npf_state_tcp_sysfini(npf_t *npf) 590 { 591 const size_t len = sizeof(npf_state_tcp_params_t); 592 npf_param_freegroup(npf, NPF_PARAMS_TCP_STATE, len); 593 } 594