1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * DCCP connection tracking protocol helper 4 * 5 * Copyright (c) 2005, 2006, 2008 Patrick McHardy <kaber@trash.net> 6 */ 7 #include <linux/kernel.h> 8 #include <linux/init.h> 9 #include <linux/sysctl.h> 10 #include <linux/spinlock.h> 11 #include <linux/skbuff.h> 12 #include <linux/dccp.h> 13 #include <linux/slab.h> 14 15 #include <net/net_namespace.h> 16 #include <net/netns/generic.h> 17 18 #include <linux/netfilter/nfnetlink_conntrack.h> 19 #include <net/netfilter/nf_conntrack.h> 20 #include <net/netfilter/nf_conntrack_l4proto.h> 21 #include <net/netfilter/nf_conntrack_ecache.h> 22 #include <net/netfilter/nf_conntrack_timeout.h> 23 #include <net/netfilter/nf_log.h> 24 25 /* Timeouts are based on values from RFC4340: 26 * 27 * - REQUEST: 28 * 29 * 8.1.2. Client Request 30 * 31 * A client MAY give up on its DCCP-Requests after some time 32 * (3 minutes, for example). 33 * 34 * - RESPOND: 35 * 36 * 8.1.3. Server Response 37 * 38 * It MAY also leave the RESPOND state for CLOSED after a timeout of 39 * not less than 4MSL (8 minutes); 40 * 41 * - PARTOPEN: 42 * 43 * 8.1.5. Handshake Completion 44 * 45 * If the client remains in PARTOPEN for more than 4MSL (8 minutes), 46 * it SHOULD reset the connection with Reset Code 2, "Aborted". 47 * 48 * - OPEN: 49 * 50 * The DCCP timestamp overflows after 11.9 hours. If the connection 51 * stays idle this long the sequence number won't be recognized 52 * as valid anymore. 53 * 54 * - CLOSEREQ/CLOSING: 55 * 56 * 8.3. Termination 57 * 58 * The retransmission timer should initially be set to go off in two 59 * round-trip times and should back off to not less than once every 60 * 64 seconds ... 61 * 62 * - TIMEWAIT: 63 * 64 * 4.3. States 65 * 66 * A server or client socket remains in this state for 2MSL (4 minutes) 67 * after the connection has been town down, ... 68 */ 69 70 #define DCCP_MSL (2 * 60 * HZ) 71 72 static const char * const dccp_state_names[] = { 73 [CT_DCCP_NONE] = "NONE", 74 [CT_DCCP_REQUEST] = "REQUEST", 75 [CT_DCCP_RESPOND] = "RESPOND", 76 [CT_DCCP_PARTOPEN] = "PARTOPEN", 77 [CT_DCCP_OPEN] = "OPEN", 78 [CT_DCCP_CLOSEREQ] = "CLOSEREQ", 79 [CT_DCCP_CLOSING] = "CLOSING", 80 [CT_DCCP_TIMEWAIT] = "TIMEWAIT", 81 [CT_DCCP_IGNORE] = "IGNORE", 82 [CT_DCCP_INVALID] = "INVALID", 83 }; 84 85 #define sNO CT_DCCP_NONE 86 #define sRQ CT_DCCP_REQUEST 87 #define sRS CT_DCCP_RESPOND 88 #define sPO CT_DCCP_PARTOPEN 89 #define sOP CT_DCCP_OPEN 90 #define sCR CT_DCCP_CLOSEREQ 91 #define sCG CT_DCCP_CLOSING 92 #define sTW CT_DCCP_TIMEWAIT 93 #define sIG CT_DCCP_IGNORE 94 #define sIV CT_DCCP_INVALID 95 96 /* 97 * DCCP state transition table 98 * 99 * The assumption is the same as for TCP tracking: 100 * 101 * We are the man in the middle. All the packets go through us but might 102 * get lost in transit to the destination. It is assumed that the destination 103 * can't receive segments we haven't seen. 104 * 105 * The following states exist: 106 * 107 * NONE: Initial state, expecting Request 108 * REQUEST: Request seen, waiting for Response from server 109 * RESPOND: Response from server seen, waiting for Ack from client 110 * PARTOPEN: Ack after Response seen, waiting for packet other than Response, 111 * Reset or Sync from server 112 * OPEN: Packet other than Response, Reset or Sync seen 113 * CLOSEREQ: CloseReq from server seen, expecting Close from client 114 * CLOSING: Close seen, expecting Reset 115 * TIMEWAIT: Reset seen 116 * IGNORE: Not determinable whether packet is valid 117 * 118 * Some states exist only on one side of the connection: REQUEST, RESPOND, 119 * PARTOPEN, CLOSEREQ. For the other side these states are equivalent to 120 * the one it was in before. 121 * 122 * Packets are marked as ignored (sIG) if we don't know if they're valid 123 * (for example a reincarnation of a connection we didn't notice is dead 124 * already) and the server may send back a connection closing Reset or a 125 * Response. They're also used for Sync/SyncAck packets, which we don't 126 * care about. 127 */ 128 static const u_int8_t 129 dccp_state_table[CT_DCCP_ROLE_MAX + 1][DCCP_PKT_SYNCACK + 1][CT_DCCP_MAX + 1] = { 130 [CT_DCCP_ROLE_CLIENT] = { 131 [DCCP_PKT_REQUEST] = { 132 /* 133 * sNO -> sRQ Regular Request 134 * sRQ -> sRQ Retransmitted Request or reincarnation 135 * sRS -> sRS Retransmitted Request (apparently Response 136 * got lost after we saw it) or reincarnation 137 * sPO -> sIG Ignore, conntrack might be out of sync 138 * sOP -> sIG Ignore, conntrack might be out of sync 139 * sCR -> sIG Ignore, conntrack might be out of sync 140 * sCG -> sIG Ignore, conntrack might be out of sync 141 * sTW -> sRQ Reincarnation 142 * 143 * sNO, sRQ, sRS, sPO. sOP, sCR, sCG, sTW, */ 144 sRQ, sRQ, sRS, sIG, sIG, sIG, sIG, sRQ, 145 }, 146 [DCCP_PKT_RESPONSE] = { 147 /* 148 * sNO -> sIV Invalid 149 * sRQ -> sIG Ignore, might be response to ignored Request 150 * sRS -> sIG Ignore, might be response to ignored Request 151 * sPO -> sIG Ignore, might be response to ignored Request 152 * sOP -> sIG Ignore, might be response to ignored Request 153 * sCR -> sIG Ignore, might be response to ignored Request 154 * sCG -> sIG Ignore, might be response to ignored Request 155 * sTW -> sIV Invalid, reincarnation in reverse direction 156 * goes through sRQ 157 * 158 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 159 sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIV, 160 }, 161 [DCCP_PKT_ACK] = { 162 /* 163 * sNO -> sIV No connection 164 * sRQ -> sIV No connection 165 * sRS -> sPO Ack for Response, move to PARTOPEN (8.1.5.) 166 * sPO -> sPO Retransmitted Ack for Response, remain in PARTOPEN 167 * sOP -> sOP Regular ACK, remain in OPEN 168 * sCR -> sCR Ack in CLOSEREQ MAY be processed (8.3.) 169 * sCG -> sCG Ack in CLOSING MAY be processed (8.3.) 170 * sTW -> sIV 171 * 172 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 173 sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV 174 }, 175 [DCCP_PKT_DATA] = { 176 /* 177 * sNO -> sIV No connection 178 * sRQ -> sIV No connection 179 * sRS -> sIV No connection 180 * sPO -> sIV MUST use DataAck in PARTOPEN state (8.1.5.) 181 * sOP -> sOP Regular Data packet 182 * sCR -> sCR Data in CLOSEREQ MAY be processed (8.3.) 183 * sCG -> sCG Data in CLOSING MAY be processed (8.3.) 184 * sTW -> sIV 185 * 186 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 187 sIV, sIV, sIV, sIV, sOP, sCR, sCG, sIV, 188 }, 189 [DCCP_PKT_DATAACK] = { 190 /* 191 * sNO -> sIV No connection 192 * sRQ -> sIV No connection 193 * sRS -> sPO Ack for Response, move to PARTOPEN (8.1.5.) 194 * sPO -> sPO Remain in PARTOPEN state 195 * sOP -> sOP Regular DataAck packet in OPEN state 196 * sCR -> sCR DataAck in CLOSEREQ MAY be processed (8.3.) 197 * sCG -> sCG DataAck in CLOSING MAY be processed (8.3.) 198 * sTW -> sIV 199 * 200 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 201 sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV 202 }, 203 [DCCP_PKT_CLOSEREQ] = { 204 /* 205 * CLOSEREQ may only be sent by the server. 206 * 207 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 208 sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV 209 }, 210 [DCCP_PKT_CLOSE] = { 211 /* 212 * sNO -> sIV No connection 213 * sRQ -> sIV No connection 214 * sRS -> sIV No connection 215 * sPO -> sCG Client-initiated close 216 * sOP -> sCG Client-initiated close 217 * sCR -> sCG Close in response to CloseReq (8.3.) 218 * sCG -> sCG Retransmit 219 * sTW -> sIV Late retransmit, already in TIME_WAIT 220 * 221 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 222 sIV, sIV, sIV, sCG, sCG, sCG, sIV, sIV 223 }, 224 [DCCP_PKT_RESET] = { 225 /* 226 * sNO -> sIV No connection 227 * sRQ -> sTW Sync received or timeout, SHOULD send Reset (8.1.1.) 228 * sRS -> sTW Response received without Request 229 * sPO -> sTW Timeout, SHOULD send Reset (8.1.5.) 230 * sOP -> sTW Connection reset 231 * sCR -> sTW Connection reset 232 * sCG -> sTW Connection reset 233 * sTW -> sIG Ignore (don't refresh timer) 234 * 235 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 236 sIV, sTW, sTW, sTW, sTW, sTW, sTW, sIG 237 }, 238 [DCCP_PKT_SYNC] = { 239 /* 240 * We currently ignore Sync packets 241 * 242 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 243 sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG, 244 }, 245 [DCCP_PKT_SYNCACK] = { 246 /* 247 * We currently ignore SyncAck packets 248 * 249 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 250 sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG, 251 }, 252 }, 253 [CT_DCCP_ROLE_SERVER] = { 254 [DCCP_PKT_REQUEST] = { 255 /* 256 * sNO -> sIV Invalid 257 * sRQ -> sIG Ignore, conntrack might be out of sync 258 * sRS -> sIG Ignore, conntrack might be out of sync 259 * sPO -> sIG Ignore, conntrack might be out of sync 260 * sOP -> sIG Ignore, conntrack might be out of sync 261 * sCR -> sIG Ignore, conntrack might be out of sync 262 * sCG -> sIG Ignore, conntrack might be out of sync 263 * sTW -> sRQ Reincarnation, must reverse roles 264 * 265 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 266 sIV, sIG, sIG, sIG, sIG, sIG, sIG, sRQ 267 }, 268 [DCCP_PKT_RESPONSE] = { 269 /* 270 * sNO -> sIV Response without Request 271 * sRQ -> sRS Response to clients Request 272 * sRS -> sRS Retransmitted Response (8.1.3. SHOULD NOT) 273 * sPO -> sIG Response to an ignored Request or late retransmit 274 * sOP -> sIG Ignore, might be response to ignored Request 275 * sCR -> sIG Ignore, might be response to ignored Request 276 * sCG -> sIG Ignore, might be response to ignored Request 277 * sTW -> sIV Invalid, Request from client in sTW moves to sRQ 278 * 279 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 280 sIV, sRS, sRS, sIG, sIG, sIG, sIG, sIV 281 }, 282 [DCCP_PKT_ACK] = { 283 /* 284 * sNO -> sIV No connection 285 * sRQ -> sIV No connection 286 * sRS -> sIV No connection 287 * sPO -> sOP Enter OPEN state (8.1.5.) 288 * sOP -> sOP Regular Ack in OPEN state 289 * sCR -> sIV Waiting for Close from client 290 * sCG -> sCG Ack in CLOSING MAY be processed (8.3.) 291 * sTW -> sIV 292 * 293 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 294 sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV 295 }, 296 [DCCP_PKT_DATA] = { 297 /* 298 * sNO -> sIV No connection 299 * sRQ -> sIV No connection 300 * sRS -> sIV No connection 301 * sPO -> sOP Enter OPEN state (8.1.5.) 302 * sOP -> sOP Regular Data packet in OPEN state 303 * sCR -> sIV Waiting for Close from client 304 * sCG -> sCG Data in CLOSING MAY be processed (8.3.) 305 * sTW -> sIV 306 * 307 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 308 sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV 309 }, 310 [DCCP_PKT_DATAACK] = { 311 /* 312 * sNO -> sIV No connection 313 * sRQ -> sIV No connection 314 * sRS -> sIV No connection 315 * sPO -> sOP Enter OPEN state (8.1.5.) 316 * sOP -> sOP Regular DataAck in OPEN state 317 * sCR -> sIV Waiting for Close from client 318 * sCG -> sCG Data in CLOSING MAY be processed (8.3.) 319 * sTW -> sIV 320 * 321 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 322 sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV 323 }, 324 [DCCP_PKT_CLOSEREQ] = { 325 /* 326 * sNO -> sIV No connection 327 * sRQ -> sIV No connection 328 * sRS -> sIV No connection 329 * sPO -> sOP -> sCR Move directly to CLOSEREQ (8.1.5.) 330 * sOP -> sCR CloseReq in OPEN state 331 * sCR -> sCR Retransmit 332 * sCG -> sCR Simultaneous close, client sends another Close 333 * sTW -> sIV Already closed 334 * 335 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 336 sIV, sIV, sIV, sCR, sCR, sCR, sCR, sIV 337 }, 338 [DCCP_PKT_CLOSE] = { 339 /* 340 * sNO -> sIV No connection 341 * sRQ -> sIV No connection 342 * sRS -> sIV No connection 343 * sPO -> sOP -> sCG Move direcly to CLOSING 344 * sOP -> sCG Move to CLOSING 345 * sCR -> sIV Close after CloseReq is invalid 346 * sCG -> sCG Retransmit 347 * sTW -> sIV Already closed 348 * 349 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 350 sIV, sIV, sIV, sCG, sCG, sIV, sCG, sIV 351 }, 352 [DCCP_PKT_RESET] = { 353 /* 354 * sNO -> sIV No connection 355 * sRQ -> sTW Reset in response to Request 356 * sRS -> sTW Timeout, SHOULD send Reset (8.1.3.) 357 * sPO -> sTW Timeout, SHOULD send Reset (8.1.3.) 358 * sOP -> sTW 359 * sCR -> sTW 360 * sCG -> sTW 361 * sTW -> sIG Ignore (don't refresh timer) 362 * 363 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW, sTW */ 364 sIV, sTW, sTW, sTW, sTW, sTW, sTW, sTW, sIG 365 }, 366 [DCCP_PKT_SYNC] = { 367 /* 368 * We currently ignore Sync packets 369 * 370 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 371 sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG, 372 }, 373 [DCCP_PKT_SYNCACK] = { 374 /* 375 * We currently ignore SyncAck packets 376 * 377 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 378 sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG, 379 }, 380 }, 381 }; 382 383 static noinline bool 384 dccp_new(struct nf_conn *ct, const struct sk_buff *skb, 385 const struct dccp_hdr *dh, 386 const struct nf_hook_state *hook_state) 387 { 388 struct net *net = nf_ct_net(ct); 389 struct nf_dccp_net *dn; 390 const char *msg; 391 u_int8_t state; 392 393 state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE]; 394 switch (state) { 395 default: 396 dn = nf_dccp_pernet(net); 397 if (dn->dccp_loose == 0) { 398 msg = "not picking up existing connection "; 399 goto out_invalid; 400 } 401 break; 402 case CT_DCCP_REQUEST: 403 break; 404 case CT_DCCP_INVALID: 405 msg = "invalid state transition "; 406 goto out_invalid; 407 } 408 409 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT; 410 ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER; 411 ct->proto.dccp.state = CT_DCCP_NONE; 412 ct->proto.dccp.last_pkt = DCCP_PKT_REQUEST; 413 ct->proto.dccp.last_dir = IP_CT_DIR_ORIGINAL; 414 ct->proto.dccp.handshake_seq = 0; 415 return true; 416 417 out_invalid: 418 nf_ct_l4proto_log_invalid(skb, ct, hook_state, "%s", msg); 419 return false; 420 } 421 422 static u64 dccp_ack_seq(const struct dccp_hdr *dh) 423 { 424 const struct dccp_hdr_ack_bits *dhack; 425 426 dhack = (void *)dh + __dccp_basic_hdr_len(dh); 427 return ((u64)ntohs(dhack->dccph_ack_nr_high) << 32) + 428 ntohl(dhack->dccph_ack_nr_low); 429 } 430 431 static bool dccp_error(const struct dccp_hdr *dh, 432 struct sk_buff *skb, unsigned int dataoff, 433 const struct nf_hook_state *state) 434 { 435 static const unsigned long require_seq48 = 1 << DCCP_PKT_REQUEST | 436 1 << DCCP_PKT_RESPONSE | 437 1 << DCCP_PKT_CLOSEREQ | 438 1 << DCCP_PKT_CLOSE | 439 1 << DCCP_PKT_RESET | 440 1 << DCCP_PKT_SYNC | 441 1 << DCCP_PKT_SYNCACK; 442 unsigned int dccp_len = skb->len - dataoff; 443 unsigned int cscov; 444 const char *msg; 445 u8 type; 446 447 BUILD_BUG_ON(DCCP_PKT_INVALID >= BITS_PER_LONG); 448 449 if (dh->dccph_doff * 4 < sizeof(struct dccp_hdr) || 450 dh->dccph_doff * 4 > dccp_len) { 451 msg = "nf_ct_dccp: truncated/malformed packet "; 452 goto out_invalid; 453 } 454 455 cscov = dccp_len; 456 if (dh->dccph_cscov) { 457 cscov = (dh->dccph_cscov - 1) * 4; 458 if (cscov > dccp_len) { 459 msg = "nf_ct_dccp: bad checksum coverage "; 460 goto out_invalid; 461 } 462 } 463 464 if (state->hook == NF_INET_PRE_ROUTING && 465 state->net->ct.sysctl_checksum && 466 nf_checksum_partial(skb, state->hook, dataoff, cscov, 467 IPPROTO_DCCP, state->pf)) { 468 msg = "nf_ct_dccp: bad checksum "; 469 goto out_invalid; 470 } 471 472 type = dh->dccph_type; 473 if (type >= DCCP_PKT_INVALID) { 474 msg = "nf_ct_dccp: reserved packet type "; 475 goto out_invalid; 476 } 477 478 if (test_bit(type, &require_seq48) && !dh->dccph_x) { 479 msg = "nf_ct_dccp: type lacks 48bit sequence numbers"; 480 goto out_invalid; 481 } 482 483 return false; 484 out_invalid: 485 nf_l4proto_log_invalid(skb, state, IPPROTO_DCCP, "%s", msg); 486 return true; 487 } 488 489 struct nf_conntrack_dccp_buf { 490 struct dccp_hdr dh; /* generic header part */ 491 struct dccp_hdr_ext ext; /* optional depending dh->dccph_x */ 492 union { /* depends on header type */ 493 struct dccp_hdr_ack_bits ack; 494 struct dccp_hdr_request req; 495 struct dccp_hdr_response response; 496 struct dccp_hdr_reset rst; 497 } u; 498 }; 499 500 static struct dccp_hdr * 501 dccp_header_pointer(const struct sk_buff *skb, int offset, const struct dccp_hdr *dh, 502 struct nf_conntrack_dccp_buf *buf) 503 { 504 unsigned int hdrlen = __dccp_hdr_len(dh); 505 506 if (hdrlen > sizeof(*buf)) 507 return NULL; 508 509 return skb_header_pointer(skb, offset, hdrlen, buf); 510 } 511 512 int nf_conntrack_dccp_packet(struct nf_conn *ct, struct sk_buff *skb, 513 unsigned int dataoff, 514 enum ip_conntrack_info ctinfo, 515 const struct nf_hook_state *state) 516 { 517 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); 518 struct nf_conntrack_dccp_buf _dh; 519 u_int8_t type, old_state, new_state; 520 enum ct_dccp_roles role; 521 unsigned int *timeouts; 522 struct dccp_hdr *dh; 523 524 dh = skb_header_pointer(skb, dataoff, sizeof(*dh), &_dh.dh); 525 if (!dh) 526 return NF_DROP; 527 528 if (dccp_error(dh, skb, dataoff, state)) 529 return -NF_ACCEPT; 530 531 /* pull again, including possible 48 bit sequences and subtype header */ 532 dh = dccp_header_pointer(skb, dataoff, dh, &_dh); 533 if (!dh) 534 return NF_DROP; 535 536 type = dh->dccph_type; 537 if (!nf_ct_is_confirmed(ct) && !dccp_new(ct, skb, dh, state)) 538 return -NF_ACCEPT; 539 540 if (type == DCCP_PKT_RESET && 541 !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { 542 /* Tear down connection immediately if only reply is a RESET */ 543 nf_ct_kill_acct(ct, ctinfo, skb); 544 return NF_ACCEPT; 545 } 546 547 spin_lock_bh(&ct->lock); 548 549 role = ct->proto.dccp.role[dir]; 550 old_state = ct->proto.dccp.state; 551 new_state = dccp_state_table[role][type][old_state]; 552 553 switch (new_state) { 554 case CT_DCCP_REQUEST: 555 if (old_state == CT_DCCP_TIMEWAIT && 556 role == CT_DCCP_ROLE_SERVER) { 557 /* Reincarnation in the reverse direction: reopen and 558 * reverse client/server roles. */ 559 ct->proto.dccp.role[dir] = CT_DCCP_ROLE_CLIENT; 560 ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_SERVER; 561 } 562 break; 563 case CT_DCCP_RESPOND: 564 if (old_state == CT_DCCP_REQUEST) 565 ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh); 566 break; 567 case CT_DCCP_PARTOPEN: 568 if (old_state == CT_DCCP_RESPOND && 569 type == DCCP_PKT_ACK && 570 dccp_ack_seq(dh) == ct->proto.dccp.handshake_seq) 571 set_bit(IPS_ASSURED_BIT, &ct->status); 572 break; 573 case CT_DCCP_IGNORE: 574 /* 575 * Connection tracking might be out of sync, so we ignore 576 * packets that might establish a new connection and resync 577 * if the server responds with a valid Response. 578 */ 579 if (ct->proto.dccp.last_dir == !dir && 580 ct->proto.dccp.last_pkt == DCCP_PKT_REQUEST && 581 type == DCCP_PKT_RESPONSE) { 582 ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_CLIENT; 583 ct->proto.dccp.role[dir] = CT_DCCP_ROLE_SERVER; 584 ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh); 585 new_state = CT_DCCP_RESPOND; 586 break; 587 } 588 ct->proto.dccp.last_dir = dir; 589 ct->proto.dccp.last_pkt = type; 590 591 spin_unlock_bh(&ct->lock); 592 nf_ct_l4proto_log_invalid(skb, ct, state, "%s", "invalid packet"); 593 return NF_ACCEPT; 594 case CT_DCCP_INVALID: 595 spin_unlock_bh(&ct->lock); 596 nf_ct_l4proto_log_invalid(skb, ct, state, "%s", "invalid state transition"); 597 return -NF_ACCEPT; 598 } 599 600 ct->proto.dccp.last_dir = dir; 601 ct->proto.dccp.last_pkt = type; 602 ct->proto.dccp.state = new_state; 603 spin_unlock_bh(&ct->lock); 604 605 if (new_state != old_state) 606 nf_conntrack_event_cache(IPCT_PROTOINFO, ct); 607 608 timeouts = nf_ct_timeout_lookup(ct); 609 if (!timeouts) 610 timeouts = nf_dccp_pernet(nf_ct_net(ct))->dccp_timeout; 611 nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[new_state]); 612 613 return NF_ACCEPT; 614 } 615 616 static bool dccp_can_early_drop(const struct nf_conn *ct) 617 { 618 switch (ct->proto.dccp.state) { 619 case CT_DCCP_CLOSEREQ: 620 case CT_DCCP_CLOSING: 621 case CT_DCCP_TIMEWAIT: 622 return true; 623 default: 624 break; 625 } 626 627 return false; 628 } 629 630 #ifdef CONFIG_NF_CONNTRACK_PROCFS 631 static void dccp_print_conntrack(struct seq_file *s, struct nf_conn *ct) 632 { 633 seq_printf(s, "%s ", dccp_state_names[ct->proto.dccp.state]); 634 } 635 #endif 636 637 #if IS_ENABLED(CONFIG_NF_CT_NETLINK) 638 static int dccp_to_nlattr(struct sk_buff *skb, struct nlattr *nla, 639 struct nf_conn *ct, bool destroy) 640 { 641 struct nlattr *nest_parms; 642 643 spin_lock_bh(&ct->lock); 644 nest_parms = nla_nest_start(skb, CTA_PROTOINFO_DCCP); 645 if (!nest_parms) 646 goto nla_put_failure; 647 if (nla_put_u8(skb, CTA_PROTOINFO_DCCP_STATE, ct->proto.dccp.state)) 648 goto nla_put_failure; 649 650 if (destroy) 651 goto skip_state; 652 653 if (nla_put_u8(skb, CTA_PROTOINFO_DCCP_ROLE, 654 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL]) || 655 nla_put_be64(skb, CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ, 656 cpu_to_be64(ct->proto.dccp.handshake_seq), 657 CTA_PROTOINFO_DCCP_PAD)) 658 goto nla_put_failure; 659 skip_state: 660 nla_nest_end(skb, nest_parms); 661 spin_unlock_bh(&ct->lock); 662 663 return 0; 664 665 nla_put_failure: 666 spin_unlock_bh(&ct->lock); 667 return -1; 668 } 669 670 static const struct nla_policy dccp_nla_policy[CTA_PROTOINFO_DCCP_MAX + 1] = { 671 [CTA_PROTOINFO_DCCP_STATE] = { .type = NLA_U8 }, 672 [CTA_PROTOINFO_DCCP_ROLE] = { .type = NLA_U8 }, 673 [CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ] = { .type = NLA_U64 }, 674 [CTA_PROTOINFO_DCCP_PAD] = { .type = NLA_UNSPEC }, 675 }; 676 677 #define DCCP_NLATTR_SIZE ( \ 678 NLA_ALIGN(NLA_HDRLEN + 1) + \ 679 NLA_ALIGN(NLA_HDRLEN + 1) + \ 680 NLA_ALIGN(NLA_HDRLEN + sizeof(u64)) + \ 681 NLA_ALIGN(NLA_HDRLEN + 0)) 682 683 static int nlattr_to_dccp(struct nlattr *cda[], struct nf_conn *ct) 684 { 685 struct nlattr *attr = cda[CTA_PROTOINFO_DCCP]; 686 struct nlattr *tb[CTA_PROTOINFO_DCCP_MAX + 1]; 687 int err; 688 689 if (!attr) 690 return 0; 691 692 err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_DCCP_MAX, attr, 693 dccp_nla_policy, NULL); 694 if (err < 0) 695 return err; 696 697 if (!tb[CTA_PROTOINFO_DCCP_STATE] || 698 !tb[CTA_PROTOINFO_DCCP_ROLE] || 699 nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) > CT_DCCP_ROLE_MAX || 700 nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]) >= CT_DCCP_IGNORE) { 701 return -EINVAL; 702 } 703 704 spin_lock_bh(&ct->lock); 705 ct->proto.dccp.state = nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]); 706 if (nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) == CT_DCCP_ROLE_CLIENT) { 707 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT; 708 ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER; 709 } else { 710 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_SERVER; 711 ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_CLIENT; 712 } 713 if (tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]) { 714 ct->proto.dccp.handshake_seq = 715 be64_to_cpu(nla_get_be64(tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ])); 716 } 717 spin_unlock_bh(&ct->lock); 718 return 0; 719 } 720 #endif 721 722 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT 723 724 #include <linux/netfilter/nfnetlink.h> 725 #include <linux/netfilter/nfnetlink_cttimeout.h> 726 727 static int dccp_timeout_nlattr_to_obj(struct nlattr *tb[], 728 struct net *net, void *data) 729 { 730 struct nf_dccp_net *dn = nf_dccp_pernet(net); 731 unsigned int *timeouts = data; 732 int i; 733 734 if (!timeouts) 735 timeouts = dn->dccp_timeout; 736 737 /* set default DCCP timeouts. */ 738 for (i=0; i<CT_DCCP_MAX; i++) 739 timeouts[i] = dn->dccp_timeout[i]; 740 741 /* there's a 1:1 mapping between attributes and protocol states. */ 742 for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) { 743 if (tb[i]) { 744 timeouts[i] = ntohl(nla_get_be32(tb[i])) * HZ; 745 } 746 } 747 748 timeouts[CTA_TIMEOUT_DCCP_UNSPEC] = timeouts[CTA_TIMEOUT_DCCP_REQUEST]; 749 return 0; 750 } 751 752 static int 753 dccp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data) 754 { 755 const unsigned int *timeouts = data; 756 int i; 757 758 for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) { 759 if (nla_put_be32(skb, i, htonl(timeouts[i] / HZ))) 760 goto nla_put_failure; 761 } 762 return 0; 763 764 nla_put_failure: 765 return -ENOSPC; 766 } 767 768 static const struct nla_policy 769 dccp_timeout_nla_policy[CTA_TIMEOUT_DCCP_MAX+1] = { 770 [CTA_TIMEOUT_DCCP_REQUEST] = { .type = NLA_U32 }, 771 [CTA_TIMEOUT_DCCP_RESPOND] = { .type = NLA_U32 }, 772 [CTA_TIMEOUT_DCCP_PARTOPEN] = { .type = NLA_U32 }, 773 [CTA_TIMEOUT_DCCP_OPEN] = { .type = NLA_U32 }, 774 [CTA_TIMEOUT_DCCP_CLOSEREQ] = { .type = NLA_U32 }, 775 [CTA_TIMEOUT_DCCP_CLOSING] = { .type = NLA_U32 }, 776 [CTA_TIMEOUT_DCCP_TIMEWAIT] = { .type = NLA_U32 }, 777 }; 778 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ 779 780 void nf_conntrack_dccp_init_net(struct net *net) 781 { 782 struct nf_dccp_net *dn = nf_dccp_pernet(net); 783 784 /* default values */ 785 dn->dccp_loose = 1; 786 dn->dccp_timeout[CT_DCCP_REQUEST] = 2 * DCCP_MSL; 787 dn->dccp_timeout[CT_DCCP_RESPOND] = 4 * DCCP_MSL; 788 dn->dccp_timeout[CT_DCCP_PARTOPEN] = 4 * DCCP_MSL; 789 dn->dccp_timeout[CT_DCCP_OPEN] = 12 * 3600 * HZ; 790 dn->dccp_timeout[CT_DCCP_CLOSEREQ] = 64 * HZ; 791 dn->dccp_timeout[CT_DCCP_CLOSING] = 64 * HZ; 792 dn->dccp_timeout[CT_DCCP_TIMEWAIT] = 2 * DCCP_MSL; 793 794 /* timeouts[0] is unused, make it same as SYN_SENT so 795 * ->timeouts[0] contains 'new' timeout, like udp or icmp. 796 */ 797 dn->dccp_timeout[CT_DCCP_NONE] = dn->dccp_timeout[CT_DCCP_REQUEST]; 798 } 799 800 const struct nf_conntrack_l4proto nf_conntrack_l4proto_dccp = { 801 .l4proto = IPPROTO_DCCP, 802 .can_early_drop = dccp_can_early_drop, 803 #ifdef CONFIG_NF_CONNTRACK_PROCFS 804 .print_conntrack = dccp_print_conntrack, 805 #endif 806 #if IS_ENABLED(CONFIG_NF_CT_NETLINK) 807 .nlattr_size = DCCP_NLATTR_SIZE, 808 .to_nlattr = dccp_to_nlattr, 809 .from_nlattr = nlattr_to_dccp, 810 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr, 811 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size, 812 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple, 813 .nla_policy = nf_ct_port_nla_policy, 814 #endif 815 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT 816 .ctnl_timeout = { 817 .nlattr_to_obj = dccp_timeout_nlattr_to_obj, 818 .obj_to_nlattr = dccp_timeout_obj_to_nlattr, 819 .nlattr_max = CTA_TIMEOUT_DCCP_MAX, 820 .obj_size = sizeof(unsigned int) * CT_DCCP_MAX, 821 .nla_policy = dccp_timeout_nla_policy, 822 }, 823 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ 824 }; 825