1 /*- 2 * Copyright (c) 2001-2002 Packet Design, LLC. 3 * All rights reserved. 4 * 5 * Subject to the following obligations and disclaimer of warranty, 6 * use and redistribution of this software, in source or object code 7 * forms, with or without modifications are expressly permitted by 8 * Packet Design; provided, however, that: 9 * 10 * (i) Any and all reproductions of the source or object code 11 * must include the copyright notice above and the following 12 * disclaimer of warranties; and 13 * (ii) No rights are granted, in any manner or form, to use 14 * Packet Design trademarks, including the mark "PACKET DESIGN" 15 * on advertising, endorsements, or otherwise except as such 16 * appears in the above copyright notice or in the software. 17 * 18 * THIS SOFTWARE IS BEING PROVIDED BY PACKET DESIGN "AS IS", AND 19 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, PACKET DESIGN MAKES NO 20 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING 21 * THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED 22 * WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, 23 * OR NON-INFRINGEMENT. PACKET DESIGN DOES NOT WARRANT, GUARANTEE, 24 * OR MAKE ANY REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS 25 * OF THE USE OF THIS SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, 26 * RELIABILITY OR OTHERWISE. IN NO EVENT SHALL PACKET DESIGN BE 27 * LIABLE FOR ANY DAMAGES RESULTING FROM OR ARISING OUT OF ANY USE 28 * OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY DIRECT, 29 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, PUNITIVE, OR CONSEQUENTIAL 30 * DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, LOSS OF 31 * USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY THEORY OF 32 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF 34 * THE USE OF THIS SOFTWARE, EVEN IF PACKET DESIGN IS ADVISED OF 35 * THE POSSIBILITY OF SUCH DAMAGE. 36 * 37 * Author: Archie Cobbs <archie@freebsd.org> 38 * 39 * $FreeBSD$ 40 */ 41 42 /* 43 * L2TP netgraph node type. 44 * 45 * This node type implements the lower layer of the 46 * L2TP protocol as specified in RFC 2661. 47 */ 48 49 #include <sys/param.h> 50 #include <sys/systm.h> 51 #include <sys/kernel.h> 52 #include <sys/time.h> 53 #include <sys/conf.h> 54 #include <sys/mbuf.h> 55 #include <sys/malloc.h> 56 #include <sys/errno.h> 57 #include <sys/libkern.h> 58 59 #include <netgraph/ng_message.h> 60 #include <netgraph/netgraph.h> 61 #include <netgraph/ng_parse.h> 62 #include <netgraph/ng_l2tp.h> 63 64 #ifdef NG_SEPARATE_MALLOC 65 MALLOC_DEFINE(M_NETGRAPH_L2TP, "netgraph_l2tp", "netgraph l2tp node"); 66 #else 67 #define M_NETGRAPH_L2TP M_NETGRAPH 68 #endif 69 70 /* L2TP header format (first 2 bytes only) */ 71 #define L2TP_HDR_CTRL 0x8000 /* control packet */ 72 #define L2TP_HDR_LEN 0x4000 /* has length field */ 73 #define L2TP_HDR_SEQ 0x0800 /* has ns, nr fields */ 74 #define L2TP_HDR_OFF 0x0200 /* has offset field */ 75 #define L2TP_HDR_PRIO 0x0100 /* give priority */ 76 #define L2TP_HDR_VERS_MASK 0x000f /* version field mask */ 77 #define L2TP_HDR_VERSION 0x0002 /* version field */ 78 79 /* Bits that must be zero or one in first two bytes of header */ 80 #define L2TP_CTRL_0BITS 0x030d /* ctrl: must be 0 */ 81 #define L2TP_CTRL_1BITS 0xc802 /* ctrl: must be 1 */ 82 #define L2TP_DATA_0BITS 0x800d /* data: must be 0 */ 83 #define L2TP_DATA_1BITS 0x0002 /* data: must be 1 */ 84 85 /* Standard xmit ctrl and data header bits */ 86 #define L2TP_CTRL_HDR (L2TP_HDR_CTRL | L2TP_HDR_LEN \ 87 | L2TP_HDR_SEQ | L2TP_HDR_VERSION) 88 #define L2TP_DATA_HDR (L2TP_HDR_VERSION) /* optional: len, seq */ 89 90 /* Some hard coded values */ 91 #define L2TP_MAX_XWIN 128 /* my max xmit window */ 92 #define L2TP_MAX_REXMIT 5 /* default max rexmit */ 93 #define L2TP_MAX_REXMIT_TO 30 /* default rexmit to */ 94 #define L2TP_DELAYED_ACK ((hz + 19) / 20) /* delayed ack: 50 ms */ 95 96 /* Default data sequence number configuration for new sessions */ 97 #define L2TP_CONTROL_DSEQ 1 /* we are the lns */ 98 #define L2TP_ENABLE_DSEQ 1 /* enable data seq # */ 99 100 /* Compare sequence numbers using circular math */ 101 #define L2TP_SEQ_DIFF(x, y) ((int)((int16_t)(x) - (int16_t)(y))) 102 103 #define SESSHASHSIZE 0x0020 104 #define SESSHASH(x) (((x) ^ ((x) >> 8)) & (SESSHASHSIZE - 1)) 105 106 /* Hook private data (data session hooks only) */ 107 struct ng_l2tp_hook_private { 108 struct ng_l2tp_sess_config conf; /* hook/session config */ 109 struct ng_l2tp_session_stats stats; /* per sessions statistics */ 110 hook_p hook; /* hook reference */ 111 u_int16_t ns; /* data ns sequence number */ 112 u_int16_t nr; /* data nr sequence number */ 113 LIST_ENTRY(ng_l2tp_hook_private) sessions; 114 }; 115 typedef struct ng_l2tp_hook_private *hookpriv_p; 116 117 /* 118 * Sequence number state 119 * 120 * Invariants: 121 * - If cwnd < ssth, we're doing slow start, otherwise congestion avoidance 122 * - The number of unacknowledged xmit packets is (ns - rack) <= seq->wmax 123 * - The first (ns - rack) mbuf's in xwin[] array are copies of these 124 * unacknowledged packets; the remainder of xwin[] consists first of 125 * zero or more further untransmitted packets in the transmit queue 126 * - We try to keep the peer's receive window as full as possible. 127 * Therefore, (i < cwnd && xwin[i] != NULL) implies (ns - rack) > i. 128 * - rack_timer is running iff (ns - rack) > 0 (unack'd xmit'd pkts) 129 * - If xack != nr, there are unacknowledged recv packet(s) (delayed ack) 130 * - xack_timer is running iff xack != nr (unack'd rec'd pkts) 131 */ 132 struct l2tp_seq { 133 u_int16_t ns; /* next xmit seq we send */ 134 u_int16_t nr; /* next recv seq we expect */ 135 u_int16_t inproc; /* packet is in processing */ 136 u_int16_t rack; /* last 'nr' we rec'd */ 137 u_int16_t xack; /* last 'nr' we sent */ 138 u_int16_t wmax; /* peer's max recv window */ 139 u_int16_t cwnd; /* current congestion window */ 140 u_int16_t ssth; /* slow start threshold */ 141 u_int16_t acks; /* # consecutive acks rec'd */ 142 u_int16_t rexmits; /* # retransmits sent */ 143 struct callout rack_timer; /* retransmit timer */ 144 struct callout xack_timer; /* delayed ack timer */ 145 struct mbuf *xwin[L2TP_MAX_XWIN]; /* transmit window */ 146 struct mtx mtx; /* seq mutex */ 147 }; 148 149 /* Node private data */ 150 struct ng_l2tp_private { 151 node_p node; /* back pointer to node */ 152 hook_p ctrl; /* hook to upper layers */ 153 hook_p lower; /* hook to lower layers */ 154 struct ng_l2tp_config conf; /* node configuration */ 155 struct ng_l2tp_stats stats; /* node statistics */ 156 struct l2tp_seq seq; /* ctrl sequence number state */ 157 ng_ID_t ftarget; /* failure message target */ 158 LIST_HEAD(, ng_l2tp_hook_private) sesshash[SESSHASHSIZE]; 159 }; 160 typedef struct ng_l2tp_private *priv_p; 161 162 /* Netgraph node methods */ 163 static ng_constructor_t ng_l2tp_constructor; 164 static ng_rcvmsg_t ng_l2tp_rcvmsg; 165 static ng_shutdown_t ng_l2tp_shutdown; 166 static ng_newhook_t ng_l2tp_newhook; 167 static ng_rcvdata_t ng_l2tp_rcvdata; 168 static ng_rcvdata_t ng_l2tp_rcvdata_lower; 169 static ng_rcvdata_t ng_l2tp_rcvdata_ctrl; 170 static ng_disconnect_t ng_l2tp_disconnect; 171 172 /* Internal functions */ 173 static int ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns); 174 175 static void ng_l2tp_seq_init(priv_p priv); 176 static int ng_l2tp_seq_set(priv_p priv, 177 const struct ng_l2tp_seq_config *conf); 178 static int ng_l2tp_seq_adjust(priv_p priv, 179 const struct ng_l2tp_config *conf); 180 static void ng_l2tp_seq_reset(priv_p priv); 181 static void ng_l2tp_seq_failure(priv_p priv); 182 static void ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr); 183 static void ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, 184 void *arg1, int arg2); 185 static void ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, 186 void *arg1, int arg2); 187 188 static hookpriv_p ng_l2tp_find_session(priv_p privp, u_int16_t sid); 189 static ng_fn_eachhook ng_l2tp_reset_session; 190 191 #ifdef INVARIANTS 192 static void ng_l2tp_seq_check(struct l2tp_seq *seq); 193 #endif 194 195 /* Parse type for struct ng_l2tp_seq_config. */ 196 static const struct ng_parse_struct_field 197 ng_l2tp_seq_config_fields[] = NG_L2TP_SEQ_CONFIG_TYPE_INFO; 198 static const struct ng_parse_type ng_l2tp_seq_config_type = { 199 &ng_parse_struct_type, 200 &ng_l2tp_seq_config_fields 201 }; 202 203 /* Parse type for struct ng_l2tp_config */ 204 static const struct ng_parse_struct_field 205 ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO; 206 static const struct ng_parse_type ng_l2tp_config_type = { 207 &ng_parse_struct_type, 208 &ng_l2tp_config_type_fields, 209 }; 210 211 /* Parse type for struct ng_l2tp_sess_config */ 212 static const struct ng_parse_struct_field 213 ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO; 214 static const struct ng_parse_type ng_l2tp_sess_config_type = { 215 &ng_parse_struct_type, 216 &ng_l2tp_sess_config_type_fields, 217 }; 218 219 /* Parse type for struct ng_l2tp_stats */ 220 static const struct ng_parse_struct_field 221 ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO; 222 static const struct ng_parse_type ng_l2tp_stats_type = { 223 &ng_parse_struct_type, 224 &ng_l2tp_stats_type_fields 225 }; 226 227 /* Parse type for struct ng_l2tp_session_stats. */ 228 static const struct ng_parse_struct_field 229 ng_l2tp_session_stats_type_fields[] = NG_L2TP_SESSION_STATS_TYPE_INFO; 230 static const struct ng_parse_type ng_l2tp_session_stats_type = { 231 &ng_parse_struct_type, 232 &ng_l2tp_session_stats_type_fields 233 }; 234 235 /* List of commands and how to convert arguments to/from ASCII */ 236 static const struct ng_cmdlist ng_l2tp_cmdlist[] = { 237 { 238 NGM_L2TP_COOKIE, 239 NGM_L2TP_SET_CONFIG, 240 "setconfig", 241 &ng_l2tp_config_type, 242 NULL 243 }, 244 { 245 NGM_L2TP_COOKIE, 246 NGM_L2TP_GET_CONFIG, 247 "getconfig", 248 NULL, 249 &ng_l2tp_config_type 250 }, 251 { 252 NGM_L2TP_COOKIE, 253 NGM_L2TP_SET_SESS_CONFIG, 254 "setsessconfig", 255 &ng_l2tp_sess_config_type, 256 NULL 257 }, 258 { 259 NGM_L2TP_COOKIE, 260 NGM_L2TP_GET_SESS_CONFIG, 261 "getsessconfig", 262 &ng_parse_hint16_type, 263 &ng_l2tp_sess_config_type 264 }, 265 { 266 NGM_L2TP_COOKIE, 267 NGM_L2TP_GET_STATS, 268 "getstats", 269 NULL, 270 &ng_l2tp_stats_type 271 }, 272 { 273 NGM_L2TP_COOKIE, 274 NGM_L2TP_CLR_STATS, 275 "clrstats", 276 NULL, 277 NULL 278 }, 279 { 280 NGM_L2TP_COOKIE, 281 NGM_L2TP_GETCLR_STATS, 282 "getclrstats", 283 NULL, 284 &ng_l2tp_stats_type 285 }, 286 { 287 NGM_L2TP_COOKIE, 288 NGM_L2TP_GET_SESSION_STATS, 289 "getsessstats", 290 &ng_parse_int16_type, 291 &ng_l2tp_session_stats_type 292 }, 293 { 294 NGM_L2TP_COOKIE, 295 NGM_L2TP_CLR_SESSION_STATS, 296 "clrsessstats", 297 &ng_parse_int16_type, 298 NULL 299 }, 300 { 301 NGM_L2TP_COOKIE, 302 NGM_L2TP_GETCLR_SESSION_STATS, 303 "getclrsessstats", 304 &ng_parse_int16_type, 305 &ng_l2tp_session_stats_type 306 }, 307 { 308 NGM_L2TP_COOKIE, 309 NGM_L2TP_ACK_FAILURE, 310 "ackfailure", 311 NULL, 312 NULL 313 }, 314 { 315 NGM_L2TP_COOKIE, 316 NGM_L2TP_SET_SEQ, 317 "setsequence", 318 &ng_l2tp_seq_config_type, 319 NULL 320 }, 321 { 0 } 322 }; 323 324 /* Node type descriptor */ 325 static struct ng_type ng_l2tp_typestruct = { 326 .version = NG_ABI_VERSION, 327 .name = NG_L2TP_NODE_TYPE, 328 .constructor = ng_l2tp_constructor, 329 .rcvmsg = ng_l2tp_rcvmsg, 330 .shutdown = ng_l2tp_shutdown, 331 .newhook = ng_l2tp_newhook, 332 .rcvdata = ng_l2tp_rcvdata, 333 .disconnect = ng_l2tp_disconnect, 334 .cmdlist = ng_l2tp_cmdlist, 335 }; 336 NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct); 337 338 /* Sequence number state sanity checking */ 339 #ifdef INVARIANTS 340 #define L2TP_SEQ_CHECK(seq) ng_l2tp_seq_check(seq) 341 #else 342 #define L2TP_SEQ_CHECK(x) do { } while (0) 343 #endif 344 345 /* memmove macro */ 346 #define memmove(d, s, l) bcopy(s, d, l) 347 348 /* Whether to use m_copypacket() or m_dup() */ 349 #define L2TP_COPY_MBUF m_copypacket 350 351 #define ERROUT(x) do { error = (x); goto done; } while (0) 352 353 /************************************************************************ 354 NETGRAPH NODE STUFF 355 ************************************************************************/ 356 357 /* 358 * Node type constructor 359 */ 360 static int 361 ng_l2tp_constructor(node_p node) 362 { 363 priv_p priv; 364 int i; 365 366 /* Allocate private structure */ 367 MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO); 368 if (priv == NULL) 369 return (ENOMEM); 370 NG_NODE_SET_PRIVATE(node, priv); 371 priv->node = node; 372 373 /* Apply a semi-reasonable default configuration */ 374 priv->conf.peer_win = 1; 375 priv->conf.rexmit_max = L2TP_MAX_REXMIT; 376 priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO; 377 378 /* Initialize sequence number state */ 379 ng_l2tp_seq_init(priv); 380 381 for (i = 0; i < SESSHASHSIZE; i++) 382 LIST_INIT(&priv->sesshash[i]); 383 384 /* Done */ 385 return (0); 386 } 387 388 /* 389 * Give our OK for a hook to be added. 390 */ 391 static int 392 ng_l2tp_newhook(node_p node, hook_p hook, const char *name) 393 { 394 const priv_p priv = NG_NODE_PRIVATE(node); 395 396 /* Check hook name */ 397 if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) { 398 if (priv->ctrl != NULL) 399 return (EISCONN); 400 priv->ctrl = hook; 401 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_ctrl); 402 } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) { 403 if (priv->lower != NULL) 404 return (EISCONN); 405 priv->lower = hook; 406 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_lower); 407 } else { 408 static const char hexdig[16] = "0123456789abcdef"; 409 u_int16_t session_id; 410 hookpriv_p hpriv; 411 uint16_t hash; 412 const char *hex; 413 int i; 414 int j; 415 416 /* Parse hook name to get session ID */ 417 if (strncmp(name, NG_L2TP_HOOK_SESSION_P, 418 sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0) 419 return (EINVAL); 420 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1; 421 for (session_id = i = 0; i < 4; i++) { 422 for (j = 0; j < 16 && hex[i] != hexdig[j]; j++); 423 if (j == 16) 424 return (EINVAL); 425 session_id = (session_id << 4) | j; 426 } 427 if (hex[i] != '\0') 428 return (EINVAL); 429 430 /* Create hook private structure */ 431 MALLOC(hpriv, hookpriv_p, 432 sizeof(*hpriv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO); 433 if (hpriv == NULL) 434 return (ENOMEM); 435 hpriv->conf.session_id = htons(session_id); 436 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ; 437 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ; 438 hpriv->hook = hook; 439 NG_HOOK_SET_PRIVATE(hook, hpriv); 440 hash = SESSHASH(hpriv->conf.session_id); 441 LIST_INSERT_HEAD(&priv->sesshash[hash], hpriv, sessions); 442 } 443 444 /* Done */ 445 return (0); 446 } 447 448 /* 449 * Receive a control message. 450 */ 451 static int 452 ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook) 453 { 454 const priv_p priv = NG_NODE_PRIVATE(node); 455 struct ng_mesg *resp = NULL; 456 struct ng_mesg *msg; 457 int error = 0; 458 459 NGI_GET_MSG(item, msg); 460 switch (msg->header.typecookie) { 461 case NGM_L2TP_COOKIE: 462 switch (msg->header.cmd) { 463 case NGM_L2TP_SET_CONFIG: 464 { 465 struct ng_l2tp_config *const conf = 466 (struct ng_l2tp_config *)msg->data; 467 468 /* Check for invalid or illegal config */ 469 if (msg->header.arglen != sizeof(*conf)) { 470 error = EINVAL; 471 break; 472 } 473 conf->enabled = !!conf->enabled; 474 conf->match_id = !!conf->match_id; 475 conf->tunnel_id = htons(conf->tunnel_id); 476 conf->peer_id = htons(conf->peer_id); 477 if (priv->conf.enabled 478 && ((priv->conf.tunnel_id != 0 479 && conf->tunnel_id != priv->conf.tunnel_id) 480 || ((priv->conf.peer_id != 0 481 && conf->peer_id != priv->conf.peer_id)))) { 482 error = EBUSY; 483 break; 484 } 485 486 /* Save calling node as failure target */ 487 priv->ftarget = NGI_RETADDR(item); 488 489 /* Adjust sequence number state */ 490 if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0) 491 break; 492 493 /* Update node's config */ 494 priv->conf = *conf; 495 break; 496 } 497 case NGM_L2TP_GET_CONFIG: 498 { 499 struct ng_l2tp_config *conf; 500 501 NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT); 502 if (resp == NULL) { 503 error = ENOMEM; 504 break; 505 } 506 conf = (struct ng_l2tp_config *)resp->data; 507 *conf = priv->conf; 508 509 /* Put ID's in host order */ 510 conf->tunnel_id = ntohs(conf->tunnel_id); 511 conf->peer_id = ntohs(conf->peer_id); 512 break; 513 } 514 case NGM_L2TP_SET_SESS_CONFIG: 515 { 516 struct ng_l2tp_sess_config *const conf = 517 (struct ng_l2tp_sess_config *)msg->data; 518 hookpriv_p hpriv; 519 520 /* Check for invalid or illegal config. */ 521 if (msg->header.arglen != sizeof(*conf)) { 522 error = EINVAL; 523 break; 524 } 525 526 /* Put ID's in network order */ 527 conf->session_id = htons(conf->session_id); 528 conf->peer_id = htons(conf->peer_id); 529 530 /* Find matching hook */ 531 hpriv = ng_l2tp_find_session(priv, conf->session_id); 532 if (hpriv == NULL) { 533 error = ENOENT; 534 break; 535 } 536 537 /* Update hook's config */ 538 hpriv->conf = *conf; 539 break; 540 } 541 case NGM_L2TP_GET_SESS_CONFIG: 542 { 543 struct ng_l2tp_sess_config *conf; 544 u_int16_t session_id; 545 hookpriv_p hpriv; 546 547 /* Get session ID */ 548 if (msg->header.arglen != sizeof(session_id)) { 549 error = EINVAL; 550 break; 551 } 552 memcpy(&session_id, msg->data, 2); 553 session_id = htons(session_id); 554 555 /* Find matching hook */ 556 hpriv = ng_l2tp_find_session(priv, session_id); 557 if (hpriv == NULL) { 558 error = ENOENT; 559 break; 560 } 561 562 /* Send response */ 563 NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT); 564 if (resp == NULL) { 565 error = ENOMEM; 566 break; 567 } 568 conf = (struct ng_l2tp_sess_config *)resp->data; 569 *conf = hpriv->conf; 570 571 /* Put ID's in host order */ 572 conf->session_id = ntohs(conf->session_id); 573 conf->peer_id = ntohs(conf->peer_id); 574 break; 575 } 576 case NGM_L2TP_GET_STATS: 577 case NGM_L2TP_CLR_STATS: 578 case NGM_L2TP_GETCLR_STATS: 579 { 580 if (msg->header.cmd != NGM_L2TP_CLR_STATS) { 581 NG_MKRESPONSE(resp, msg, 582 sizeof(priv->stats), M_NOWAIT); 583 if (resp == NULL) { 584 error = ENOMEM; 585 break; 586 } 587 memcpy(resp->data, 588 &priv->stats, sizeof(priv->stats)); 589 } 590 if (msg->header.cmd != NGM_L2TP_GET_STATS) 591 memset(&priv->stats, 0, sizeof(priv->stats)); 592 break; 593 } 594 case NGM_L2TP_GET_SESSION_STATS: 595 case NGM_L2TP_CLR_SESSION_STATS: 596 case NGM_L2TP_GETCLR_SESSION_STATS: 597 { 598 uint16_t session_id; 599 hookpriv_p hpriv; 600 601 /* Get session ID. */ 602 if (msg->header.arglen != sizeof(session_id)) { 603 error = EINVAL; 604 break; 605 } 606 bcopy(msg->data, &session_id, sizeof(uint16_t)); 607 session_id = htons(session_id); 608 609 /* Find matching hook. */ 610 hpriv = ng_l2tp_find_session(priv, session_id); 611 if (hpriv == NULL) { 612 error = ENOENT; 613 break; 614 } 615 616 if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) { 617 NG_MKRESPONSE(resp, msg, 618 sizeof(hpriv->stats), M_NOWAIT); 619 if (resp == NULL) { 620 error = ENOMEM; 621 break; 622 } 623 bcopy(&hpriv->stats, resp->data, 624 sizeof(hpriv->stats)); 625 } 626 if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS) 627 bzero(&hpriv->stats, sizeof(hpriv->stats)); 628 break; 629 } 630 case NGM_L2TP_SET_SEQ: 631 { 632 struct ng_l2tp_seq_config *const conf = 633 (struct ng_l2tp_seq_config *)msg->data; 634 635 /* Check for invalid or illegal seq config. */ 636 if (msg->header.arglen != sizeof(*conf)) { 637 error = EINVAL; 638 break; 639 } 640 conf->ns = htons(conf->ns); 641 conf->nr = htons(conf->nr); 642 conf->rack = htons(conf->rack); 643 conf->xack = htons(conf->xack); 644 645 /* Set sequence numbers. */ 646 error = ng_l2tp_seq_set(priv, conf); 647 break; 648 } 649 default: 650 error = EINVAL; 651 break; 652 } 653 break; 654 default: 655 error = EINVAL; 656 break; 657 } 658 659 /* Done */ 660 NG_RESPOND_MSG(error, node, item, resp); 661 NG_FREE_MSG(msg); 662 return (error); 663 } 664 665 /* 666 * Destroy node 667 */ 668 static int 669 ng_l2tp_shutdown(node_p node) 670 { 671 const priv_p priv = NG_NODE_PRIVATE(node); 672 struct l2tp_seq *const seq = &priv->seq; 673 674 /* Sanity check */ 675 L2TP_SEQ_CHECK(seq); 676 677 /* Reset sequence number state */ 678 ng_l2tp_seq_reset(priv); 679 680 /* Free private data if neither timer is running */ 681 ng_uncallout(&seq->rack_timer, node); 682 ng_uncallout(&seq->xack_timer, node); 683 684 mtx_destroy(&seq->mtx); 685 686 FREE(priv, M_NETGRAPH_L2TP); 687 688 /* Unref node */ 689 NG_NODE_UNREF(node); 690 return (0); 691 } 692 693 /* 694 * Hook disconnection 695 */ 696 static int 697 ng_l2tp_disconnect(hook_p hook) 698 { 699 const node_p node = NG_HOOK_NODE(hook); 700 const priv_p priv = NG_NODE_PRIVATE(node); 701 702 /* Zero out hook pointer */ 703 if (hook == priv->ctrl) 704 priv->ctrl = NULL; 705 else if (hook == priv->lower) 706 priv->lower = NULL; 707 else { 708 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook); 709 LIST_REMOVE(hpriv, sessions); 710 FREE(hpriv, M_NETGRAPH_L2TP); 711 NG_HOOK_SET_PRIVATE(hook, NULL); 712 } 713 714 /* Go away if no longer connected to anything */ 715 if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node)) 716 ng_rmnode_self(node); 717 return (0); 718 } 719 720 /************************************************************************* 721 INTERNAL FUNCTIONS 722 *************************************************************************/ 723 724 /* 725 * Find the hook with a given session ID (in network order). 726 */ 727 static hookpriv_p 728 ng_l2tp_find_session(priv_p privp, u_int16_t sid) 729 { 730 uint16_t hash = SESSHASH(sid); 731 hookpriv_p hpriv = NULL; 732 733 LIST_FOREACH(hpriv, &privp->sesshash[hash], sessions) { 734 if (hpriv->conf.session_id == sid) 735 break; 736 } 737 738 return (hpriv); 739 } 740 741 /* 742 * Reset a hook's session state. 743 */ 744 static int 745 ng_l2tp_reset_session(hook_p hook, void *arg) 746 { 747 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook); 748 749 if (hpriv != NULL) { 750 hpriv->conf.control_dseq = 0; 751 hpriv->conf.enable_dseq = 0; 752 bzero(&hpriv->conf, sizeof(struct ng_l2tp_session_stats)); 753 hpriv->nr = 0; 754 hpriv->ns = 0; 755 } 756 return (-1); 757 } 758 759 /* 760 * Handle an incoming frame from below. 761 */ 762 static int 763 ng_l2tp_rcvdata_lower(hook_p h, item_p item) 764 { 765 static const u_int16_t req_bits[2][2] = { 766 { L2TP_DATA_0BITS, L2TP_DATA_1BITS }, 767 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS }, 768 }; 769 const node_p node = NG_HOOK_NODE(h); 770 const priv_p priv = NG_NODE_PRIVATE(node); 771 hookpriv_p hpriv = NULL; 772 hook_p hook = NULL; 773 u_int16_t ids[2]; 774 struct mbuf *m; 775 u_int16_t hdr; 776 u_int16_t ns; 777 u_int16_t nr; 778 int is_ctrl; 779 int error; 780 int len, plen; 781 782 /* Sanity check */ 783 L2TP_SEQ_CHECK(&priv->seq); 784 785 /* If not configured, reject */ 786 if (!priv->conf.enabled) { 787 NG_FREE_ITEM(item); 788 ERROUT(ENXIO); 789 } 790 791 /* Grab mbuf */ 792 NGI_GET_M(item, m); 793 794 /* Remember full packet length; needed for per session accounting. */ 795 plen = m->m_pkthdr.len; 796 797 /* Update stats */ 798 priv->stats.recvPackets++; 799 priv->stats.recvOctets += plen; 800 801 /* Get initial header */ 802 if (m->m_pkthdr.len < 6) { 803 priv->stats.recvRunts++; 804 NG_FREE_ITEM(item); 805 NG_FREE_M(m); 806 ERROUT(EINVAL); 807 } 808 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) { 809 priv->stats.memoryFailures++; 810 NG_FREE_ITEM(item); 811 ERROUT(EINVAL); 812 } 813 hdr = ntohs(*mtod(m, u_int16_t *)); 814 m_adj(m, 2); 815 816 /* Check required header bits and minimum length */ 817 is_ctrl = (hdr & L2TP_HDR_CTRL) != 0; 818 if ((hdr & req_bits[is_ctrl][0]) != 0 819 || (~hdr & req_bits[is_ctrl][1]) != 0) { 820 priv->stats.recvInvalid++; 821 NG_FREE_ITEM(item); 822 NG_FREE_M(m); 823 ERROUT(EINVAL); 824 } 825 if (m->m_pkthdr.len < 4 /* tunnel, session id */ 826 + (2 * ((hdr & L2TP_HDR_LEN) != 0)) /* length field */ 827 + (4 * ((hdr & L2TP_HDR_SEQ) != 0)) /* seq # fields */ 828 + (2 * ((hdr & L2TP_HDR_OFF) != 0))) { /* offset field */ 829 priv->stats.recvRunts++; 830 NG_FREE_ITEM(item); 831 NG_FREE_M(m); 832 ERROUT(EINVAL); 833 } 834 835 /* Get and validate length field if present */ 836 if ((hdr & L2TP_HDR_LEN) != 0) { 837 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) { 838 priv->stats.memoryFailures++; 839 NG_FREE_ITEM(item); 840 ERROUT(EINVAL); 841 } 842 len = (u_int16_t)ntohs(*mtod(m, u_int16_t *)) - 4; 843 m_adj(m, 2); 844 if (len < 0 || len > m->m_pkthdr.len) { 845 priv->stats.recvInvalid++; 846 NG_FREE_ITEM(item); 847 NG_FREE_M(m); 848 ERROUT(EINVAL); 849 } 850 if (len < m->m_pkthdr.len) /* trim extra bytes */ 851 m_adj(m, -(m->m_pkthdr.len - len)); 852 } 853 854 /* Get tunnel ID and session ID */ 855 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) { 856 priv->stats.memoryFailures++; 857 NG_FREE_ITEM(item); 858 ERROUT(EINVAL); 859 } 860 memcpy(ids, mtod(m, u_int16_t *), 4); 861 m_adj(m, 4); 862 863 /* Check tunnel ID */ 864 if (ids[0] != priv->conf.tunnel_id 865 && (priv->conf.match_id || ids[0] != 0)) { 866 priv->stats.recvWrongTunnel++; 867 NG_FREE_ITEM(item); 868 NG_FREE_M(m); 869 ERROUT(EADDRNOTAVAIL); 870 } 871 872 /* Check session ID (for data packets only) */ 873 if ((hdr & L2TP_HDR_CTRL) == 0) { 874 hpriv = ng_l2tp_find_session(priv, ids[1]); 875 if (hpriv == NULL) { 876 priv->stats.recvUnknownSID++; 877 NG_FREE_ITEM(item); 878 NG_FREE_M(m); 879 ERROUT(ENOTCONN); 880 } 881 hook = hpriv->hook; 882 } 883 884 /* Get Ns, Nr fields if present */ 885 if ((hdr & L2TP_HDR_SEQ) != 0) { 886 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) { 887 priv->stats.memoryFailures++; 888 NG_FREE_ITEM(item); 889 ERROUT(EINVAL); 890 } 891 memcpy(&ns, &mtod(m, u_int16_t *)[0], 2); 892 ns = ntohs(ns); 893 memcpy(&nr, &mtod(m, u_int16_t *)[1], 2); 894 nr = ntohs(nr); 895 m_adj(m, 4); 896 } 897 898 /* Strip offset padding if present */ 899 if ((hdr & L2TP_HDR_OFF) != 0) { 900 u_int16_t offset; 901 902 /* Get length of offset padding */ 903 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) { 904 priv->stats.memoryFailures++; 905 NG_FREE_ITEM(item); 906 ERROUT(EINVAL); 907 } 908 memcpy(&offset, mtod(m, u_int16_t *), 2); 909 offset = ntohs(offset); 910 911 /* Trim offset padding */ 912 if ((2+offset) > m->m_pkthdr.len) { 913 priv->stats.recvInvalid++; 914 NG_FREE_ITEM(item); 915 NG_FREE_M(m); 916 ERROUT(EINVAL); 917 } 918 m_adj(m, 2+offset); 919 } 920 921 /* Handle control packets */ 922 if ((hdr & L2TP_HDR_CTRL) != 0) { 923 struct l2tp_seq *const seq = &priv->seq; 924 925 /* Handle receive ack sequence number Nr */ 926 ng_l2tp_seq_recv_nr(priv, nr); 927 928 /* Discard ZLB packets */ 929 if (m->m_pkthdr.len == 0) { 930 priv->stats.recvZLBs++; 931 NG_FREE_ITEM(item); 932 NG_FREE_M(m); 933 ERROUT(0); 934 } 935 936 mtx_lock(&seq->mtx); 937 /* 938 * If not what we expect or we are busy, drop packet and 939 * send an immediate ZLB ack. 940 */ 941 if (ns != seq->nr || seq->inproc) { 942 if (L2TP_SEQ_DIFF(ns, seq->nr) <= 0) 943 priv->stats.recvDuplicates++; 944 else 945 priv->stats.recvOutOfOrder++; 946 mtx_unlock(&seq->mtx); 947 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns); 948 NG_FREE_ITEM(item); 949 NG_FREE_M(m); 950 ERROUT(0); 951 } 952 /* 953 * Until we deliver this packet we can't receive next one as 954 * we have no information for sending ack. 955 */ 956 seq->inproc = 1; 957 mtx_unlock(&seq->mtx); 958 959 /* Prepend session ID to packet. */ 960 M_PREPEND(m, 2, M_DONTWAIT); 961 if (m == NULL) { 962 seq->inproc = 0; 963 priv->stats.memoryFailures++; 964 NG_FREE_ITEM(item); 965 ERROUT(ENOBUFS); 966 } 967 memcpy(mtod(m, u_int16_t *), &ids[1], 2); 968 969 /* Deliver packet to upper layers */ 970 NG_FWD_NEW_DATA(error, item, priv->ctrl, m); 971 972 mtx_lock(&seq->mtx); 973 /* Ready to process next packet. */ 974 seq->inproc = 0; 975 976 /* If packet was successfully delivered send ack. */ 977 if (error == 0) { 978 /* Update recv sequence number */ 979 seq->nr++; 980 /* Start receive ack timer, if not already running */ 981 if (!callout_active(&seq->xack_timer)) { 982 ng_callout(&seq->xack_timer, priv->node, NULL, 983 L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout, 984 NULL, 0); 985 } 986 } 987 mtx_unlock(&seq->mtx); 988 989 ERROUT(error); 990 } 991 992 /* Per session packet, account it. */ 993 hpriv->stats.recvPackets++; 994 hpriv->stats.recvOctets += plen; 995 996 /* Follow peer's lead in data sequencing, if configured to do so */ 997 if (!hpriv->conf.control_dseq) 998 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0); 999 1000 /* Handle data sequence numbers if present and enabled */ 1001 if ((hdr & L2TP_HDR_SEQ) != 0) { 1002 if (hpriv->conf.enable_dseq 1003 && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) { 1004 NG_FREE_ITEM(item); /* duplicate or out of order */ 1005 NG_FREE_M(m); 1006 priv->stats.recvDataDrops++; 1007 ERROUT(0); 1008 } 1009 hpriv->nr = ns + 1; 1010 } 1011 1012 /* Drop empty data packets */ 1013 if (m->m_pkthdr.len == 0) { 1014 NG_FREE_ITEM(item); 1015 NG_FREE_M(m); 1016 ERROUT(0); 1017 } 1018 1019 /* Deliver data */ 1020 NG_FWD_NEW_DATA(error, item, hook, m); 1021 done: 1022 /* Done */ 1023 L2TP_SEQ_CHECK(&priv->seq); 1024 return (error); 1025 } 1026 1027 /* 1028 * Handle an outgoing control frame. 1029 */ 1030 static int 1031 ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item) 1032 { 1033 const node_p node = NG_HOOK_NODE(hook); 1034 const priv_p priv = NG_NODE_PRIVATE(node); 1035 struct l2tp_seq *const seq = &priv->seq; 1036 struct mbuf *m; 1037 int error; 1038 int i; 1039 u_int16_t ns; 1040 1041 /* Sanity check */ 1042 L2TP_SEQ_CHECK(&priv->seq); 1043 1044 /* If not configured, reject */ 1045 if (!priv->conf.enabled) { 1046 NG_FREE_ITEM(item); 1047 ERROUT(ENXIO); 1048 } 1049 1050 /* Grab mbuf and discard other stuff XXX */ 1051 NGI_GET_M(item, m); 1052 NG_FREE_ITEM(item); 1053 1054 /* Packet should have session ID prepended */ 1055 if (m->m_pkthdr.len < 2) { 1056 priv->stats.xmitInvalid++; 1057 m_freem(m); 1058 ERROUT(EINVAL); 1059 } 1060 1061 /* Check max length */ 1062 if (m->m_pkthdr.len >= 0x10000 - 14) { 1063 priv->stats.xmitTooBig++; 1064 m_freem(m); 1065 ERROUT(EOVERFLOW); 1066 } 1067 1068 mtx_lock(&seq->mtx); 1069 1070 /* Find next empty slot in transmit queue */ 1071 for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++); 1072 if (i == L2TP_MAX_XWIN) { 1073 mtx_unlock(&seq->mtx); 1074 priv->stats.xmitDrops++; 1075 m_freem(m); 1076 ERROUT(ENOBUFS); 1077 } 1078 seq->xwin[i] = m; 1079 1080 /* If peer's receive window is already full, nothing else to do */ 1081 if (i >= seq->cwnd) { 1082 mtx_unlock(&seq->mtx); 1083 ERROUT(0); 1084 } 1085 1086 /* Start retransmit timer if not already running */ 1087 if (!callout_active(&seq->rack_timer)) 1088 ng_callout(&seq->rack_timer, node, NULL, 1089 hz, ng_l2tp_seq_rack_timeout, NULL, 0); 1090 1091 ns = seq->ns++; 1092 1093 mtx_unlock(&seq->mtx); 1094 1095 /* Copy packet */ 1096 if ((m = L2TP_COPY_MBUF(m, M_DONTWAIT)) == NULL) { 1097 priv->stats.memoryFailures++; 1098 ERROUT(ENOBUFS); 1099 } 1100 1101 /* Send packet and increment xmit sequence number */ 1102 error = ng_l2tp_xmit_ctrl(priv, m, ns); 1103 done: 1104 /* Done */ 1105 L2TP_SEQ_CHECK(&priv->seq); 1106 return (error); 1107 } 1108 1109 /* 1110 * Handle an outgoing data frame. 1111 */ 1112 static int 1113 ng_l2tp_rcvdata(hook_p hook, item_p item) 1114 { 1115 const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook)); 1116 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook); 1117 struct mbuf *m; 1118 u_int16_t hdr; 1119 int error; 1120 int i = 1; 1121 1122 /* Sanity check */ 1123 L2TP_SEQ_CHECK(&priv->seq); 1124 1125 /* If not configured, reject */ 1126 if (!priv->conf.enabled) { 1127 NG_FREE_ITEM(item); 1128 ERROUT(ENXIO); 1129 } 1130 1131 /* Get mbuf */ 1132 NGI_GET_M(item, m); 1133 1134 /* Check max length */ 1135 if (m->m_pkthdr.len >= 0x10000 - 12) { 1136 priv->stats.xmitDataTooBig++; 1137 NG_FREE_ITEM(item); 1138 NG_FREE_M(m); 1139 ERROUT(EOVERFLOW); 1140 } 1141 1142 /* Prepend L2TP header */ 1143 M_PREPEND(m, 6 1144 + (2 * (hpriv->conf.include_length != 0)) 1145 + (4 * (hpriv->conf.enable_dseq != 0)), 1146 M_DONTWAIT); 1147 if (m == NULL) { 1148 priv->stats.memoryFailures++; 1149 NG_FREE_ITEM(item); 1150 ERROUT(ENOBUFS); 1151 } 1152 hdr = L2TP_DATA_HDR; 1153 if (hpriv->conf.include_length) { 1154 hdr |= L2TP_HDR_LEN; 1155 mtod(m, u_int16_t *)[i++] = htons(m->m_pkthdr.len); 1156 } 1157 mtod(m, u_int16_t *)[i++] = priv->conf.peer_id; 1158 mtod(m, u_int16_t *)[i++] = hpriv->conf.peer_id; 1159 if (hpriv->conf.enable_dseq) { 1160 hdr |= L2TP_HDR_SEQ; 1161 mtod(m, u_int16_t *)[i++] = htons(hpriv->ns); 1162 mtod(m, u_int16_t *)[i++] = htons(hpriv->nr); 1163 hpriv->ns++; 1164 } 1165 mtod(m, u_int16_t *)[0] = htons(hdr); 1166 1167 /* Update per session stats. */ 1168 hpriv->stats.xmitPackets++; 1169 hpriv->stats.xmitOctets += m->m_pkthdr.len; 1170 1171 /* And the global one. */ 1172 priv->stats.xmitPackets++; 1173 priv->stats.xmitOctets += m->m_pkthdr.len; 1174 1175 /* Send packet */ 1176 NG_FWD_NEW_DATA(error, item, priv->lower, m); 1177 done: 1178 /* Done */ 1179 L2TP_SEQ_CHECK(&priv->seq); 1180 return (error); 1181 } 1182 1183 /* 1184 * Send a message to our controlling node that we've failed. 1185 */ 1186 static void 1187 ng_l2tp_seq_failure(priv_p priv) 1188 { 1189 struct ng_mesg *msg; 1190 int error; 1191 1192 NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT); 1193 if (msg == NULL) 1194 return; 1195 NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0); 1196 } 1197 1198 /************************************************************************ 1199 SEQUENCE NUMBER HANDLING 1200 ************************************************************************/ 1201 1202 /* 1203 * Initialize sequence number state. 1204 */ 1205 static void 1206 ng_l2tp_seq_init(priv_p priv) 1207 { 1208 struct l2tp_seq *const seq = &priv->seq; 1209 1210 KASSERT(priv->conf.peer_win >= 1, 1211 ("%s: peer_win is zero", __func__)); 1212 memset(seq, 0, sizeof(*seq)); 1213 seq->cwnd = 1; 1214 seq->wmax = priv->conf.peer_win; 1215 if (seq->wmax > L2TP_MAX_XWIN) 1216 seq->wmax = L2TP_MAX_XWIN; 1217 seq->ssth = seq->wmax; 1218 ng_callout_init(&seq->rack_timer); 1219 ng_callout_init(&seq->xack_timer); 1220 mtx_init(&seq->mtx, "ng_l2tp", NULL, MTX_DEF); 1221 L2TP_SEQ_CHECK(seq); 1222 } 1223 1224 /* 1225 * Set sequence number state as given from user. 1226 */ 1227 static int 1228 ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf) 1229 { 1230 struct l2tp_seq *const seq = &priv->seq; 1231 1232 /* If node is enabled, deny update to sequence numbers. */ 1233 if (priv->conf.enabled) 1234 return (EBUSY); 1235 1236 /* We only can handle the simple cases. */ 1237 if (conf->xack != conf->nr || conf->ns != conf->rack) 1238 return (EINVAL); 1239 1240 /* Set ns,nr,rack,xack parameters. */ 1241 seq->ns = conf->ns; 1242 seq->nr = conf->nr; 1243 seq->rack = conf->rack; 1244 seq->xack = conf->xack; 1245 1246 return (0); 1247 } 1248 1249 /* 1250 * Adjust sequence number state accordingly after reconfiguration. 1251 */ 1252 static int 1253 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf) 1254 { 1255 struct l2tp_seq *const seq = &priv->seq; 1256 u_int16_t new_wmax; 1257 1258 /* If disabling node, reset state sequence number */ 1259 if (!conf->enabled) { 1260 ng_l2tp_seq_reset(priv); 1261 return (0); 1262 } 1263 1264 /* Adjust peer's max recv window; it can only increase */ 1265 new_wmax = conf->peer_win; 1266 if (new_wmax > L2TP_MAX_XWIN) 1267 new_wmax = L2TP_MAX_XWIN; 1268 if (new_wmax == 0) 1269 return (EINVAL); 1270 if (new_wmax < seq->wmax) 1271 return (EBUSY); 1272 seq->wmax = new_wmax; 1273 1274 /* Done */ 1275 return (0); 1276 } 1277 1278 /* 1279 * Reset sequence number state. 1280 */ 1281 static void 1282 ng_l2tp_seq_reset(priv_p priv) 1283 { 1284 struct l2tp_seq *const seq = &priv->seq; 1285 hook_p hook; 1286 int i; 1287 1288 /* Sanity check */ 1289 L2TP_SEQ_CHECK(seq); 1290 1291 /* Stop timers */ 1292 ng_uncallout(&seq->rack_timer, priv->node); 1293 ng_uncallout(&seq->xack_timer, priv->node); 1294 1295 /* Free retransmit queue */ 1296 for (i = 0; i < L2TP_MAX_XWIN; i++) { 1297 if (seq->xwin[i] == NULL) 1298 break; 1299 m_freem(seq->xwin[i]); 1300 } 1301 1302 /* Reset session hooks' sequence number states */ 1303 NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook); 1304 1305 /* Reset node's sequence number state */ 1306 seq->ns = 0; 1307 seq->nr = 0; 1308 seq->rack = 0; 1309 seq->xack = 0; 1310 seq->wmax = L2TP_MAX_XWIN; 1311 seq->cwnd = 1; 1312 seq->ssth = seq->wmax; 1313 seq->acks = 0; 1314 seq->rexmits = 0; 1315 bzero(seq->xwin, sizeof(seq->xwin)); 1316 1317 /* Done */ 1318 L2TP_SEQ_CHECK(seq); 1319 } 1320 1321 /* 1322 * Handle receipt of an acknowledgement value (Nr) from peer. 1323 */ 1324 static void 1325 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr) 1326 { 1327 struct l2tp_seq *const seq = &priv->seq; 1328 struct mbuf *xwin[L2TP_MAX_XWIN]; /* partial local copy */ 1329 int nack; 1330 int i, j; 1331 uint16_t ns; 1332 1333 mtx_lock(&seq->mtx); 1334 1335 /* Verify peer's ACK is in range */ 1336 if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0) { 1337 mtx_unlock(&seq->mtx); 1338 return; /* duplicate ack */ 1339 } 1340 if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) { 1341 mtx_unlock(&seq->mtx); 1342 priv->stats.recvBadAcks++; /* ack for packet not sent */ 1343 return; 1344 } 1345 KASSERT(nack <= L2TP_MAX_XWIN, 1346 ("%s: nack=%d > %d", __func__, nack, L2TP_MAX_XWIN)); 1347 1348 /* Update receive ack stats */ 1349 seq->rack = nr; 1350 seq->rexmits = 0; 1351 1352 /* Free acknowledged packets and shift up packets in the xmit queue */ 1353 for (i = 0; i < nack; i++) 1354 m_freem(seq->xwin[i]); 1355 memmove(seq->xwin, seq->xwin + nack, 1356 (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin)); 1357 memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0, 1358 nack * sizeof(*seq->xwin)); 1359 1360 /* 1361 * Do slow-start/congestion avoidance windowing algorithm described 1362 * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each 1363 * ACK had arrived separately. 1364 */ 1365 if (seq->cwnd < seq->wmax) { 1366 1367 /* Handle slow start phase */ 1368 if (seq->cwnd < seq->ssth) { 1369 seq->cwnd += nack; 1370 nack = 0; 1371 if (seq->cwnd > seq->ssth) { /* into cg.av. phase */ 1372 nack = seq->cwnd - seq->ssth; 1373 seq->cwnd = seq->ssth; 1374 } 1375 } 1376 1377 /* Handle congestion avoidance phase */ 1378 if (seq->cwnd >= seq->ssth) { 1379 seq->acks += nack; 1380 while (seq->acks >= seq->cwnd) { 1381 seq->acks -= seq->cwnd; 1382 if (seq->cwnd < seq->wmax) 1383 seq->cwnd++; 1384 } 1385 } 1386 } 1387 1388 /* Stop xmit timer */ 1389 if (callout_active(&seq->rack_timer)) 1390 ng_uncallout(&seq->rack_timer, priv->node); 1391 1392 /* If transmit queue is empty, we're done for now */ 1393 if (seq->xwin[0] == NULL) { 1394 mtx_unlock(&seq->mtx); 1395 return; 1396 } 1397 1398 /* Start restransmit timer again */ 1399 ng_callout(&seq->rack_timer, priv->node, NULL, 1400 hz, ng_l2tp_seq_rack_timeout, NULL, 0); 1401 1402 /* 1403 * Send more packets, trying to keep peer's receive window full. 1404 * Make copy of everything we need before lock release. 1405 */ 1406 ns = seq->ns; 1407 j = 0; 1408 while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd 1409 && seq->xwin[i] != NULL) { 1410 xwin[j++] = seq->xwin[i]; 1411 seq->ns++; 1412 } 1413 1414 mtx_unlock(&seq->mtx); 1415 1416 /* 1417 * Send prepared. 1418 * If there is a memory error, pretend packet was sent, as it 1419 * will get retransmitted later anyway. 1420 */ 1421 for (i = 0; i < j; i++) { 1422 struct mbuf *m; 1423 if ((m = L2TP_COPY_MBUF(xwin[i], M_DONTWAIT)) == NULL) 1424 priv->stats.memoryFailures++; 1425 else 1426 ng_l2tp_xmit_ctrl(priv, m, ns); 1427 ns++; 1428 } 1429 } 1430 1431 /* 1432 * Handle an ack timeout. We have an outstanding ack that we 1433 * were hoping to piggy-back, but haven't, so send a ZLB. 1434 */ 1435 static void 1436 ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, void *arg1, int arg2) 1437 { 1438 const priv_p priv = NG_NODE_PRIVATE(node); 1439 struct l2tp_seq *const seq = &priv->seq; 1440 1441 /* Make sure callout is still active before doing anything */ 1442 if (callout_pending(&seq->xack_timer) || 1443 (!callout_active(&seq->xack_timer))) 1444 return; 1445 1446 /* Sanity check */ 1447 L2TP_SEQ_CHECK(seq); 1448 1449 /* Send a ZLB */ 1450 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns); 1451 1452 /* callout_deactivate() is not needed here 1453 as ng_uncallout() was called by ng_l2tp_xmit_ctrl() */ 1454 1455 /* Sanity check */ 1456 L2TP_SEQ_CHECK(seq); 1457 } 1458 1459 /* 1460 * Handle a transmit timeout. The peer has failed to respond 1461 * with an ack for our packet, so retransmit it. 1462 */ 1463 static void 1464 ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2) 1465 { 1466 const priv_p priv = NG_NODE_PRIVATE(node); 1467 struct l2tp_seq *const seq = &priv->seq; 1468 struct mbuf *m; 1469 u_int delay; 1470 1471 /* Make sure callout is still active before doing anything */ 1472 if (callout_pending(&seq->rack_timer) || 1473 (!callout_active(&seq->rack_timer))) 1474 return; 1475 1476 /* Sanity check */ 1477 L2TP_SEQ_CHECK(seq); 1478 1479 priv->stats.xmitRetransmits++; 1480 1481 /* Have we reached the retransmit limit? If so, notify owner. */ 1482 if (seq->rexmits++ >= priv->conf.rexmit_max) 1483 ng_l2tp_seq_failure(priv); 1484 1485 /* Restart timer, this time with an increased delay */ 1486 delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits); 1487 if (delay > priv->conf.rexmit_max_to) 1488 delay = priv->conf.rexmit_max_to; 1489 ng_callout(&seq->rack_timer, node, NULL, 1490 hz * delay, ng_l2tp_seq_rack_timeout, NULL, 0); 1491 1492 /* Do slow-start/congestion algorithm windowing algorithm */ 1493 seq->ns = seq->rack; 1494 seq->ssth = (seq->cwnd + 1) / 2; 1495 seq->cwnd = 1; 1496 seq->acks = 0; 1497 1498 /* Retransmit oldest unack'd packet */ 1499 if ((m = L2TP_COPY_MBUF(seq->xwin[0], M_DONTWAIT)) == NULL) 1500 priv->stats.memoryFailures++; 1501 else 1502 ng_l2tp_xmit_ctrl(priv, m, seq->ns++); 1503 1504 /* callout_deactivate() is not needed here 1505 as ng_callout() is getting called each time */ 1506 1507 /* Sanity check */ 1508 L2TP_SEQ_CHECK(seq); 1509 } 1510 1511 /* 1512 * Transmit a control stream packet, payload optional. 1513 * The transmit sequence number is not incremented. 1514 */ 1515 static int 1516 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns) 1517 { 1518 struct l2tp_seq *const seq = &priv->seq; 1519 u_int16_t session_id = 0; 1520 int error; 1521 1522 mtx_lock(&seq->mtx); 1523 1524 /* Stop ack timer: we're sending an ack with this packet. 1525 Doing this before to keep state predictable after error. */ 1526 if (callout_active(&seq->xack_timer)) 1527 ng_uncallout(&seq->xack_timer, priv->node); 1528 1529 seq->xack = seq->nr; 1530 1531 mtx_unlock(&seq->mtx); 1532 1533 /* If no mbuf passed, send an empty packet (ZLB) */ 1534 if (m == NULL) { 1535 1536 /* Create a new mbuf for ZLB packet */ 1537 MGETHDR(m, M_DONTWAIT, MT_DATA); 1538 if (m == NULL) { 1539 priv->stats.memoryFailures++; 1540 return (ENOBUFS); 1541 } 1542 m->m_len = m->m_pkthdr.len = 12; 1543 m->m_pkthdr.rcvif = NULL; 1544 priv->stats.xmitZLBs++; 1545 } else { 1546 1547 /* Strip off session ID */ 1548 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) { 1549 priv->stats.memoryFailures++; 1550 return (ENOBUFS); 1551 } 1552 memcpy(&session_id, mtod(m, u_int16_t *), 2); 1553 m_adj(m, 2); 1554 1555 /* Make room for L2TP header */ 1556 M_PREPEND(m, 12, M_DONTWAIT); 1557 if (m == NULL) { 1558 priv->stats.memoryFailures++; 1559 return (ENOBUFS); 1560 } 1561 } 1562 1563 /* Fill in L2TP header */ 1564 mtod(m, u_int16_t *)[0] = htons(L2TP_CTRL_HDR); 1565 mtod(m, u_int16_t *)[1] = htons(m->m_pkthdr.len); 1566 mtod(m, u_int16_t *)[2] = priv->conf.peer_id; 1567 mtod(m, u_int16_t *)[3] = session_id; 1568 mtod(m, u_int16_t *)[4] = htons(ns); 1569 mtod(m, u_int16_t *)[5] = htons(seq->nr); 1570 1571 /* Update sequence number info and stats */ 1572 priv->stats.xmitPackets++; 1573 priv->stats.xmitOctets += m->m_pkthdr.len; 1574 1575 /* Send packet */ 1576 NG_SEND_DATA_ONLY(error, priv->lower, m); 1577 return (error); 1578 } 1579 1580 #ifdef INVARIANTS 1581 /* 1582 * Sanity check sequence number state. 1583 */ 1584 static void 1585 ng_l2tp_seq_check(struct l2tp_seq *seq) 1586 { 1587 int self_unack, peer_unack; 1588 int i; 1589 1590 #define CHECK(p) KASSERT((p), ("%s: not: %s", __func__, #p)) 1591 1592 mtx_lock(&seq->mtx); 1593 1594 self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack); 1595 peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack); 1596 CHECK(seq->wmax <= L2TP_MAX_XWIN); 1597 CHECK(seq->cwnd >= 1); 1598 CHECK(seq->cwnd <= seq->wmax); 1599 CHECK(seq->ssth >= 1); 1600 CHECK(seq->ssth <= seq->wmax); 1601 if (seq->cwnd < seq->ssth) 1602 CHECK(seq->acks == 0); 1603 else 1604 CHECK(seq->acks <= seq->cwnd); 1605 CHECK(self_unack >= 0); 1606 CHECK(peer_unack >= 0); 1607 CHECK(peer_unack <= seq->wmax); 1608 CHECK((self_unack == 0) ^ callout_active(&seq->xack_timer)); 1609 CHECK((peer_unack == 0) ^ callout_active(&seq->rack_timer)); 1610 for (i = 0; i < peer_unack; i++) 1611 CHECK(seq->xwin[i] != NULL); 1612 for ( ; i < seq->cwnd; i++) /* verify peer's recv window full */ 1613 CHECK(seq->xwin[i] == NULL); 1614 1615 mtx_unlock(&seq->mtx); 1616 1617 #undef CHECK 1618 } 1619 #endif /* INVARIANTS */ 1620