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 #ifdef CONFIG_NF_CONNTRACK_PROCFS 73 static const char * const dccp_state_names[] = { 74 [CT_DCCP_NONE] = "NONE", 75 [CT_DCCP_REQUEST] = "REQUEST", 76 [CT_DCCP_RESPOND] = "RESPOND", 77 [CT_DCCP_PARTOPEN] = "PARTOPEN", 78 [CT_DCCP_OPEN] = "OPEN", 79 [CT_DCCP_CLOSEREQ] = "CLOSEREQ", 80 [CT_DCCP_CLOSING] = "CLOSING", 81 [CT_DCCP_TIMEWAIT] = "TIMEWAIT", 82 [CT_DCCP_IGNORE] = "IGNORE", 83 [CT_DCCP_INVALID] = "INVALID", 84 }; 85 #endif 86 87 #define sNO CT_DCCP_NONE 88 #define sRQ CT_DCCP_REQUEST 89 #define sRS CT_DCCP_RESPOND 90 #define sPO CT_DCCP_PARTOPEN 91 #define sOP CT_DCCP_OPEN 92 #define sCR CT_DCCP_CLOSEREQ 93 #define sCG CT_DCCP_CLOSING 94 #define sTW CT_DCCP_TIMEWAIT 95 #define sIG CT_DCCP_IGNORE 96 #define sIV CT_DCCP_INVALID 97 98 /* 99 * DCCP state transition table 100 * 101 * The assumption is the same as for TCP tracking: 102 * 103 * We are the man in the middle. All the packets go through us but might 104 * get lost in transit to the destination. It is assumed that the destination 105 * can't receive segments we haven't seen. 106 * 107 * The following states exist: 108 * 109 * NONE: Initial state, expecting Request 110 * REQUEST: Request seen, waiting for Response from server 111 * RESPOND: Response from server seen, waiting for Ack from client 112 * PARTOPEN: Ack after Response seen, waiting for packet other than Response, 113 * Reset or Sync from server 114 * OPEN: Packet other than Response, Reset or Sync seen 115 * CLOSEREQ: CloseReq from server seen, expecting Close from client 116 * CLOSING: Close seen, expecting Reset 117 * TIMEWAIT: Reset seen 118 * IGNORE: Not determinable whether packet is valid 119 * 120 * Some states exist only on one side of the connection: REQUEST, RESPOND, 121 * PARTOPEN, CLOSEREQ. For the other side these states are equivalent to 122 * the one it was in before. 123 * 124 * Packets are marked as ignored (sIG) if we don't know if they're valid 125 * (for example a reincarnation of a connection we didn't notice is dead 126 * already) and the server may send back a connection closing Reset or a 127 * Response. They're also used for Sync/SyncAck packets, which we don't 128 * care about. 129 */ 130 static const u_int8_t 131 dccp_state_table[CT_DCCP_ROLE_MAX + 1][DCCP_PKT_SYNCACK + 1][CT_DCCP_MAX + 1] = { 132 [CT_DCCP_ROLE_CLIENT] = { 133 [DCCP_PKT_REQUEST] = { 134 /* 135 * sNO -> sRQ Regular Request 136 * sRQ -> sRQ Retransmitted Request or reincarnation 137 * sRS -> sRS Retransmitted Request (apparently Response 138 * got lost after we saw it) or reincarnation 139 * sPO -> sIG Ignore, conntrack might be out of sync 140 * sOP -> sIG Ignore, conntrack might be out of sync 141 * sCR -> sIG Ignore, conntrack might be out of sync 142 * sCG -> sIG Ignore, conntrack might be out of sync 143 * sTW -> sRQ Reincarnation 144 * 145 * sNO, sRQ, sRS, sPO. sOP, sCR, sCG, sTW, */ 146 sRQ, sRQ, sRS, sIG, sIG, sIG, sIG, sRQ, 147 }, 148 [DCCP_PKT_RESPONSE] = { 149 /* 150 * sNO -> sIV Invalid 151 * sRQ -> sIG Ignore, might be response to ignored Request 152 * sRS -> sIG Ignore, might be response to ignored Request 153 * sPO -> sIG Ignore, might be response to ignored Request 154 * sOP -> sIG Ignore, might be response to ignored Request 155 * sCR -> sIG Ignore, might be response to ignored Request 156 * sCG -> sIG Ignore, might be response to ignored Request 157 * sTW -> sIV Invalid, reincarnation in reverse direction 158 * goes through sRQ 159 * 160 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 161 sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIV, 162 }, 163 [DCCP_PKT_ACK] = { 164 /* 165 * sNO -> sIV No connection 166 * sRQ -> sIV No connection 167 * sRS -> sPO Ack for Response, move to PARTOPEN (8.1.5.) 168 * sPO -> sPO Retransmitted Ack for Response, remain in PARTOPEN 169 * sOP -> sOP Regular ACK, remain in OPEN 170 * sCR -> sCR Ack in CLOSEREQ MAY be processed (8.3.) 171 * sCG -> sCG Ack in CLOSING MAY be processed (8.3.) 172 * sTW -> sIV 173 * 174 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 175 sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV 176 }, 177 [DCCP_PKT_DATA] = { 178 /* 179 * sNO -> sIV No connection 180 * sRQ -> sIV No connection 181 * sRS -> sIV No connection 182 * sPO -> sIV MUST use DataAck in PARTOPEN state (8.1.5.) 183 * sOP -> sOP Regular Data packet 184 * sCR -> sCR Data in CLOSEREQ MAY be processed (8.3.) 185 * sCG -> sCG Data in CLOSING MAY be processed (8.3.) 186 * sTW -> sIV 187 * 188 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 189 sIV, sIV, sIV, sIV, sOP, sCR, sCG, sIV, 190 }, 191 [DCCP_PKT_DATAACK] = { 192 /* 193 * sNO -> sIV No connection 194 * sRQ -> sIV No connection 195 * sRS -> sPO Ack for Response, move to PARTOPEN (8.1.5.) 196 * sPO -> sPO Remain in PARTOPEN state 197 * sOP -> sOP Regular DataAck packet in OPEN state 198 * sCR -> sCR DataAck in CLOSEREQ MAY be processed (8.3.) 199 * sCG -> sCG DataAck in CLOSING MAY be processed (8.3.) 200 * sTW -> sIV 201 * 202 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 203 sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV 204 }, 205 [DCCP_PKT_CLOSEREQ] = { 206 /* 207 * CLOSEREQ may only be sent by the server. 208 * 209 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 210 sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV 211 }, 212 [DCCP_PKT_CLOSE] = { 213 /* 214 * sNO -> sIV No connection 215 * sRQ -> sIV No connection 216 * sRS -> sIV No connection 217 * sPO -> sCG Client-initiated close 218 * sOP -> sCG Client-initiated close 219 * sCR -> sCG Close in response to CloseReq (8.3.) 220 * sCG -> sCG Retransmit 221 * sTW -> sIV Late retransmit, already in TIME_WAIT 222 * 223 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 224 sIV, sIV, sIV, sCG, sCG, sCG, sIV, sIV 225 }, 226 [DCCP_PKT_RESET] = { 227 /* 228 * sNO -> sIV No connection 229 * sRQ -> sTW Sync received or timeout, SHOULD send Reset (8.1.1.) 230 * sRS -> sTW Response received without Request 231 * sPO -> sTW Timeout, SHOULD send Reset (8.1.5.) 232 * sOP -> sTW Connection reset 233 * sCR -> sTW Connection reset 234 * sCG -> sTW Connection reset 235 * sTW -> sIG Ignore (don't refresh timer) 236 * 237 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 238 sIV, sTW, sTW, sTW, sTW, sTW, sTW, sIG 239 }, 240 [DCCP_PKT_SYNC] = { 241 /* 242 * We currently ignore Sync packets 243 * 244 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 245 sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG, 246 }, 247 [DCCP_PKT_SYNCACK] = { 248 /* 249 * We currently ignore SyncAck packets 250 * 251 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 252 sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG, 253 }, 254 }, 255 [CT_DCCP_ROLE_SERVER] = { 256 [DCCP_PKT_REQUEST] = { 257 /* 258 * sNO -> sIV Invalid 259 * sRQ -> sIG Ignore, conntrack might be out of sync 260 * sRS -> sIG Ignore, conntrack might be out of sync 261 * sPO -> sIG Ignore, conntrack might be out of sync 262 * sOP -> sIG Ignore, conntrack might be out of sync 263 * sCR -> sIG Ignore, conntrack might be out of sync 264 * sCG -> sIG Ignore, conntrack might be out of sync 265 * sTW -> sRQ Reincarnation, must reverse roles 266 * 267 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 268 sIV, sIG, sIG, sIG, sIG, sIG, sIG, sRQ 269 }, 270 [DCCP_PKT_RESPONSE] = { 271 /* 272 * sNO -> sIV Response without Request 273 * sRQ -> sRS Response to clients Request 274 * sRS -> sRS Retransmitted Response (8.1.3. SHOULD NOT) 275 * sPO -> sIG Response to an ignored Request or late retransmit 276 * sOP -> sIG Ignore, might be response to ignored Request 277 * sCR -> sIG Ignore, might be response to ignored Request 278 * sCG -> sIG Ignore, might be response to ignored Request 279 * sTW -> sIV Invalid, Request from client in sTW moves to sRQ 280 * 281 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 282 sIV, sRS, sRS, sIG, sIG, sIG, sIG, sIV 283 }, 284 [DCCP_PKT_ACK] = { 285 /* 286 * sNO -> sIV No connection 287 * sRQ -> sIV No connection 288 * sRS -> sIV No connection 289 * sPO -> sOP Enter OPEN state (8.1.5.) 290 * sOP -> sOP Regular Ack in OPEN state 291 * sCR -> sIV Waiting for Close from client 292 * sCG -> sCG Ack in CLOSING MAY be processed (8.3.) 293 * sTW -> sIV 294 * 295 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 296 sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV 297 }, 298 [DCCP_PKT_DATA] = { 299 /* 300 * sNO -> sIV No connection 301 * sRQ -> sIV No connection 302 * sRS -> sIV No connection 303 * sPO -> sOP Enter OPEN state (8.1.5.) 304 * sOP -> sOP Regular Data packet in OPEN state 305 * sCR -> sIV Waiting for Close from client 306 * sCG -> sCG Data in CLOSING MAY be processed (8.3.) 307 * sTW -> sIV 308 * 309 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 310 sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV 311 }, 312 [DCCP_PKT_DATAACK] = { 313 /* 314 * sNO -> sIV No connection 315 * sRQ -> sIV No connection 316 * sRS -> sIV No connection 317 * sPO -> sOP Enter OPEN state (8.1.5.) 318 * sOP -> sOP Regular DataAck in OPEN state 319 * sCR -> sIV Waiting for Close from client 320 * sCG -> sCG Data in CLOSING MAY be processed (8.3.) 321 * sTW -> sIV 322 * 323 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 324 sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV 325 }, 326 [DCCP_PKT_CLOSEREQ] = { 327 /* 328 * sNO -> sIV No connection 329 * sRQ -> sIV No connection 330 * sRS -> sIV No connection 331 * sPO -> sOP -> sCR Move directly to CLOSEREQ (8.1.5.) 332 * sOP -> sCR CloseReq in OPEN state 333 * sCR -> sCR Retransmit 334 * sCG -> sCR Simultaneous close, client sends another Close 335 * sTW -> sIV Already closed 336 * 337 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 338 sIV, sIV, sIV, sCR, sCR, sCR, sCR, sIV 339 }, 340 [DCCP_PKT_CLOSE] = { 341 /* 342 * sNO -> sIV No connection 343 * sRQ -> sIV No connection 344 * sRS -> sIV No connection 345 * sPO -> sOP -> sCG Move direcly to CLOSING 346 * sOP -> sCG Move to CLOSING 347 * sCR -> sIV Close after CloseReq is invalid 348 * sCG -> sCG Retransmit 349 * sTW -> sIV Already closed 350 * 351 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 352 sIV, sIV, sIV, sCG, sCG, sIV, sCG, sIV 353 }, 354 [DCCP_PKT_RESET] = { 355 /* 356 * sNO -> sIV No connection 357 * sRQ -> sTW Reset in response to Request 358 * sRS -> sTW Timeout, SHOULD send Reset (8.1.3.) 359 * sPO -> sTW Timeout, SHOULD send Reset (8.1.3.) 360 * sOP -> sTW 361 * sCR -> sTW 362 * sCG -> sTW 363 * sTW -> sIG Ignore (don't refresh timer) 364 * 365 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW, sTW */ 366 sIV, sTW, sTW, sTW, sTW, sTW, sTW, sTW, sIG 367 }, 368 [DCCP_PKT_SYNC] = { 369 /* 370 * We currently ignore Sync packets 371 * 372 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 373 sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG, 374 }, 375 [DCCP_PKT_SYNCACK] = { 376 /* 377 * We currently ignore SyncAck packets 378 * 379 * sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */ 380 sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG, 381 }, 382 }, 383 }; 384 385 static noinline bool 386 dccp_new(struct nf_conn *ct, const struct sk_buff *skb, 387 const struct dccp_hdr *dh, 388 const struct nf_hook_state *hook_state) 389 { 390 struct net *net = nf_ct_net(ct); 391 struct nf_dccp_net *dn; 392 const char *msg; 393 u_int8_t state; 394 395 state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE]; 396 switch (state) { 397 default: 398 dn = nf_dccp_pernet(net); 399 if (dn->dccp_loose == 0) { 400 msg = "not picking up existing connection "; 401 goto out_invalid; 402 } 403 break; 404 case CT_DCCP_REQUEST: 405 break; 406 case CT_DCCP_INVALID: 407 msg = "invalid state transition "; 408 goto out_invalid; 409 } 410 411 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT; 412 ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER; 413 ct->proto.dccp.state = CT_DCCP_NONE; 414 ct->proto.dccp.last_pkt = DCCP_PKT_REQUEST; 415 ct->proto.dccp.last_dir = IP_CT_DIR_ORIGINAL; 416 ct->proto.dccp.handshake_seq = 0; 417 return true; 418 419 out_invalid: 420 nf_ct_l4proto_log_invalid(skb, ct, hook_state, "%s", msg); 421 return false; 422 } 423 424 static u64 dccp_ack_seq(const struct dccp_hdr *dh) 425 { 426 const struct dccp_hdr_ack_bits *dhack; 427 428 dhack = (void *)dh + __dccp_basic_hdr_len(dh); 429 return ((u64)ntohs(dhack->dccph_ack_nr_high) << 32) + 430 ntohl(dhack->dccph_ack_nr_low); 431 } 432 433 static bool dccp_error(const struct dccp_hdr *dh, 434 struct sk_buff *skb, unsigned int dataoff, 435 const struct nf_hook_state *state) 436 { 437 static const unsigned long require_seq48 = 1 << DCCP_PKT_REQUEST | 438 1 << DCCP_PKT_RESPONSE | 439 1 << DCCP_PKT_CLOSEREQ | 440 1 << DCCP_PKT_CLOSE | 441 1 << DCCP_PKT_RESET | 442 1 << DCCP_PKT_SYNC | 443 1 << DCCP_PKT_SYNCACK; 444 unsigned int dccp_len = skb->len - dataoff; 445 unsigned int cscov; 446 const char *msg; 447 u8 type; 448 449 BUILD_BUG_ON(DCCP_PKT_INVALID >= BITS_PER_LONG); 450 451 if (dh->dccph_doff * 4 < sizeof(struct dccp_hdr) || 452 dh->dccph_doff * 4 > dccp_len) { 453 msg = "nf_ct_dccp: truncated/malformed packet "; 454 goto out_invalid; 455 } 456 457 cscov = dccp_len; 458 if (dh->dccph_cscov) { 459 cscov = (dh->dccph_cscov - 1) * 4; 460 if (cscov > dccp_len) { 461 msg = "nf_ct_dccp: bad checksum coverage "; 462 goto out_invalid; 463 } 464 } 465 466 if (state->hook == NF_INET_PRE_ROUTING && 467 state->net->ct.sysctl_checksum && 468 nf_checksum_partial(skb, state->hook, dataoff, cscov, 469 IPPROTO_DCCP, state->pf)) { 470 msg = "nf_ct_dccp: bad checksum "; 471 goto out_invalid; 472 } 473 474 type = dh->dccph_type; 475 if (type >= DCCP_PKT_INVALID) { 476 msg = "nf_ct_dccp: reserved packet type "; 477 goto out_invalid; 478 } 479 480 if (test_bit(type, &require_seq48) && !dh->dccph_x) { 481 msg = "nf_ct_dccp: type lacks 48bit sequence numbers"; 482 goto out_invalid; 483 } 484 485 return false; 486 out_invalid: 487 nf_l4proto_log_invalid(skb, state, IPPROTO_DCCP, "%s", msg); 488 return true; 489 } 490 491 struct nf_conntrack_dccp_buf { 492 struct dccp_hdr dh; /* generic header part */ 493 struct dccp_hdr_ext ext; /* optional depending dh->dccph_x */ 494 union { /* depends on header type */ 495 struct dccp_hdr_ack_bits ack; 496 struct dccp_hdr_request req; 497 struct dccp_hdr_response response; 498 struct dccp_hdr_reset rst; 499 } u; 500 }; 501 502 static struct dccp_hdr * 503 dccp_header_pointer(const struct sk_buff *skb, int offset, const struct dccp_hdr *dh, 504 struct nf_conntrack_dccp_buf *buf) 505 { 506 unsigned int hdrlen = __dccp_hdr_len(dh); 507 508 if (hdrlen > sizeof(*buf)) 509 return NULL; 510 511 return skb_header_pointer(skb, offset, hdrlen, buf); 512 } 513 514 int nf_conntrack_dccp_packet(struct nf_conn *ct, struct sk_buff *skb, 515 unsigned int dataoff, 516 enum ip_conntrack_info ctinfo, 517 const struct nf_hook_state *state) 518 { 519 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); 520 struct nf_conntrack_dccp_buf _dh; 521 u_int8_t type, old_state, new_state; 522 enum ct_dccp_roles role; 523 unsigned int *timeouts; 524 struct dccp_hdr *dh; 525 526 dh = skb_header_pointer(skb, dataoff, sizeof(*dh), &_dh.dh); 527 if (!dh) 528 return -NF_ACCEPT; 529 530 if (dccp_error(dh, skb, dataoff, state)) 531 return -NF_ACCEPT; 532 533 /* pull again, including possible 48 bit sequences and subtype header */ 534 dh = dccp_header_pointer(skb, dataoff, dh, &_dh); 535 if (!dh) 536 return -NF_ACCEPT; 537 538 type = dh->dccph_type; 539 if (!nf_ct_is_confirmed(ct) && !dccp_new(ct, skb, dh, state)) 540 return -NF_ACCEPT; 541 542 if (type == DCCP_PKT_RESET && 543 !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { 544 /* Tear down connection immediately if only reply is a RESET */ 545 nf_ct_kill_acct(ct, ctinfo, skb); 546 return NF_ACCEPT; 547 } 548 549 spin_lock_bh(&ct->lock); 550 551 role = ct->proto.dccp.role[dir]; 552 old_state = ct->proto.dccp.state; 553 new_state = dccp_state_table[role][type][old_state]; 554 555 switch (new_state) { 556 case CT_DCCP_REQUEST: 557 if (old_state == CT_DCCP_TIMEWAIT && 558 role == CT_DCCP_ROLE_SERVER) { 559 /* Reincarnation in the reverse direction: reopen and 560 * reverse client/server roles. */ 561 ct->proto.dccp.role[dir] = CT_DCCP_ROLE_CLIENT; 562 ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_SERVER; 563 } 564 break; 565 case CT_DCCP_RESPOND: 566 if (old_state == CT_DCCP_REQUEST) 567 ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh); 568 break; 569 case CT_DCCP_PARTOPEN: 570 if (old_state == CT_DCCP_RESPOND && 571 type == DCCP_PKT_ACK && 572 dccp_ack_seq(dh) == ct->proto.dccp.handshake_seq) 573 set_bit(IPS_ASSURED_BIT, &ct->status); 574 break; 575 case CT_DCCP_IGNORE: 576 /* 577 * Connection tracking might be out of sync, so we ignore 578 * packets that might establish a new connection and resync 579 * if the server responds with a valid Response. 580 */ 581 if (ct->proto.dccp.last_dir == !dir && 582 ct->proto.dccp.last_pkt == DCCP_PKT_REQUEST && 583 type == DCCP_PKT_RESPONSE) { 584 ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_CLIENT; 585 ct->proto.dccp.role[dir] = CT_DCCP_ROLE_SERVER; 586 ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh); 587 new_state = CT_DCCP_RESPOND; 588 break; 589 } 590 ct->proto.dccp.last_dir = dir; 591 ct->proto.dccp.last_pkt = type; 592 593 spin_unlock_bh(&ct->lock); 594 nf_ct_l4proto_log_invalid(skb, ct, state, "%s", "invalid packet"); 595 return NF_ACCEPT; 596 case CT_DCCP_INVALID: 597 spin_unlock_bh(&ct->lock); 598 nf_ct_l4proto_log_invalid(skb, ct, state, "%s", "invalid state transition"); 599 return -NF_ACCEPT; 600 } 601 602 ct->proto.dccp.last_dir = dir; 603 ct->proto.dccp.last_pkt = type; 604 ct->proto.dccp.state = new_state; 605 spin_unlock_bh(&ct->lock); 606 607 if (new_state != old_state) 608 nf_conntrack_event_cache(IPCT_PROTOINFO, ct); 609 610 timeouts = nf_ct_timeout_lookup(ct); 611 if (!timeouts) 612 timeouts = nf_dccp_pernet(nf_ct_net(ct))->dccp_timeout; 613 nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[new_state]); 614 615 return NF_ACCEPT; 616 } 617 618 static bool dccp_can_early_drop(const struct nf_conn *ct) 619 { 620 switch (ct->proto.dccp.state) { 621 case CT_DCCP_CLOSEREQ: 622 case CT_DCCP_CLOSING: 623 case CT_DCCP_TIMEWAIT: 624 return true; 625 default: 626 break; 627 } 628 629 return false; 630 } 631 632 #ifdef CONFIG_NF_CONNTRACK_PROCFS 633 static void dccp_print_conntrack(struct seq_file *s, struct nf_conn *ct) 634 { 635 seq_printf(s, "%s ", dccp_state_names[ct->proto.dccp.state]); 636 } 637 #endif 638 639 #if IS_ENABLED(CONFIG_NF_CT_NETLINK) 640 static int dccp_to_nlattr(struct sk_buff *skb, struct nlattr *nla, 641 struct nf_conn *ct, bool destroy) 642 { 643 struct nlattr *nest_parms; 644 645 spin_lock_bh(&ct->lock); 646 nest_parms = nla_nest_start(skb, CTA_PROTOINFO_DCCP); 647 if (!nest_parms) 648 goto nla_put_failure; 649 if (nla_put_u8(skb, CTA_PROTOINFO_DCCP_STATE, ct->proto.dccp.state)) 650 goto nla_put_failure; 651 652 if (destroy) 653 goto skip_state; 654 655 if (nla_put_u8(skb, CTA_PROTOINFO_DCCP_ROLE, 656 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL]) || 657 nla_put_be64(skb, CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ, 658 cpu_to_be64(ct->proto.dccp.handshake_seq), 659 CTA_PROTOINFO_DCCP_PAD)) 660 goto nla_put_failure; 661 skip_state: 662 nla_nest_end(skb, nest_parms); 663 spin_unlock_bh(&ct->lock); 664 665 return 0; 666 667 nla_put_failure: 668 spin_unlock_bh(&ct->lock); 669 return -1; 670 } 671 672 static const struct nla_policy dccp_nla_policy[CTA_PROTOINFO_DCCP_MAX + 1] = { 673 [CTA_PROTOINFO_DCCP_STATE] = { .type = NLA_U8 }, 674 [CTA_PROTOINFO_DCCP_ROLE] = { .type = NLA_U8 }, 675 [CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ] = { .type = NLA_U64 }, 676 [CTA_PROTOINFO_DCCP_PAD] = { .type = NLA_UNSPEC }, 677 }; 678 679 #define DCCP_NLATTR_SIZE ( \ 680 NLA_ALIGN(NLA_HDRLEN + 1) + \ 681 NLA_ALIGN(NLA_HDRLEN + 1) + \ 682 NLA_ALIGN(NLA_HDRLEN + sizeof(u64)) + \ 683 NLA_ALIGN(NLA_HDRLEN + 0)) 684 685 static int nlattr_to_dccp(struct nlattr *cda[], struct nf_conn *ct) 686 { 687 struct nlattr *attr = cda[CTA_PROTOINFO_DCCP]; 688 struct nlattr *tb[CTA_PROTOINFO_DCCP_MAX + 1]; 689 int err; 690 691 if (!attr) 692 return 0; 693 694 err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_DCCP_MAX, attr, 695 dccp_nla_policy, NULL); 696 if (err < 0) 697 return err; 698 699 if (!tb[CTA_PROTOINFO_DCCP_STATE] || 700 !tb[CTA_PROTOINFO_DCCP_ROLE] || 701 nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) > CT_DCCP_ROLE_MAX || 702 nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]) >= CT_DCCP_IGNORE) { 703 return -EINVAL; 704 } 705 706 spin_lock_bh(&ct->lock); 707 ct->proto.dccp.state = nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]); 708 if (nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) == CT_DCCP_ROLE_CLIENT) { 709 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT; 710 ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER; 711 } else { 712 ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_SERVER; 713 ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_CLIENT; 714 } 715 if (tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]) { 716 ct->proto.dccp.handshake_seq = 717 be64_to_cpu(nla_get_be64(tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ])); 718 } 719 spin_unlock_bh(&ct->lock); 720 return 0; 721 } 722 #endif 723 724 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT 725 726 #include <linux/netfilter/nfnetlink.h> 727 #include <linux/netfilter/nfnetlink_cttimeout.h> 728 729 static int dccp_timeout_nlattr_to_obj(struct nlattr *tb[], 730 struct net *net, void *data) 731 { 732 struct nf_dccp_net *dn = nf_dccp_pernet(net); 733 unsigned int *timeouts = data; 734 int i; 735 736 if (!timeouts) 737 timeouts = dn->dccp_timeout; 738 739 /* set default DCCP timeouts. */ 740 for (i=0; i<CT_DCCP_MAX; i++) 741 timeouts[i] = dn->dccp_timeout[i]; 742 743 /* there's a 1:1 mapping between attributes and protocol states. */ 744 for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) { 745 if (tb[i]) { 746 timeouts[i] = ntohl(nla_get_be32(tb[i])) * HZ; 747 } 748 } 749 750 timeouts[CTA_TIMEOUT_DCCP_UNSPEC] = timeouts[CTA_TIMEOUT_DCCP_REQUEST]; 751 return 0; 752 } 753 754 static int 755 dccp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data) 756 { 757 const unsigned int *timeouts = data; 758 int i; 759 760 for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) { 761 if (nla_put_be32(skb, i, htonl(timeouts[i] / HZ))) 762 goto nla_put_failure; 763 } 764 return 0; 765 766 nla_put_failure: 767 return -ENOSPC; 768 } 769 770 static const struct nla_policy 771 dccp_timeout_nla_policy[CTA_TIMEOUT_DCCP_MAX+1] = { 772 [CTA_TIMEOUT_DCCP_REQUEST] = { .type = NLA_U32 }, 773 [CTA_TIMEOUT_DCCP_RESPOND] = { .type = NLA_U32 }, 774 [CTA_TIMEOUT_DCCP_PARTOPEN] = { .type = NLA_U32 }, 775 [CTA_TIMEOUT_DCCP_OPEN] = { .type = NLA_U32 }, 776 [CTA_TIMEOUT_DCCP_CLOSEREQ] = { .type = NLA_U32 }, 777 [CTA_TIMEOUT_DCCP_CLOSING] = { .type = NLA_U32 }, 778 [CTA_TIMEOUT_DCCP_TIMEWAIT] = { .type = NLA_U32 }, 779 }; 780 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ 781 782 void nf_conntrack_dccp_init_net(struct net *net) 783 { 784 struct nf_dccp_net *dn = nf_dccp_pernet(net); 785 786 /* default values */ 787 dn->dccp_loose = 1; 788 dn->dccp_timeout[CT_DCCP_REQUEST] = 2 * DCCP_MSL; 789 dn->dccp_timeout[CT_DCCP_RESPOND] = 4 * DCCP_MSL; 790 dn->dccp_timeout[CT_DCCP_PARTOPEN] = 4 * DCCP_MSL; 791 dn->dccp_timeout[CT_DCCP_OPEN] = 12 * 3600 * HZ; 792 dn->dccp_timeout[CT_DCCP_CLOSEREQ] = 64 * HZ; 793 dn->dccp_timeout[CT_DCCP_CLOSING] = 64 * HZ; 794 dn->dccp_timeout[CT_DCCP_TIMEWAIT] = 2 * DCCP_MSL; 795 796 /* timeouts[0] is unused, make it same as SYN_SENT so 797 * ->timeouts[0] contains 'new' timeout, like udp or icmp. 798 */ 799 dn->dccp_timeout[CT_DCCP_NONE] = dn->dccp_timeout[CT_DCCP_REQUEST]; 800 } 801 802 const struct nf_conntrack_l4proto nf_conntrack_l4proto_dccp = { 803 .l4proto = IPPROTO_DCCP, 804 .can_early_drop = dccp_can_early_drop, 805 #ifdef CONFIG_NF_CONNTRACK_PROCFS 806 .print_conntrack = dccp_print_conntrack, 807 #endif 808 #if IS_ENABLED(CONFIG_NF_CT_NETLINK) 809 .nlattr_size = DCCP_NLATTR_SIZE, 810 .to_nlattr = dccp_to_nlattr, 811 .from_nlattr = nlattr_to_dccp, 812 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr, 813 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size, 814 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple, 815 .nla_policy = nf_ct_port_nla_policy, 816 #endif 817 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT 818 .ctnl_timeout = { 819 .nlattr_to_obj = dccp_timeout_nlattr_to_obj, 820 .obj_to_nlattr = dccp_timeout_obj_to_nlattr, 821 .nlattr_max = CTA_TIMEOUT_DCCP_MAX, 822 .obj_size = sizeof(unsigned int) * CT_DCCP_MAX, 823 .nla_policy = dccp_timeout_nla_policy, 824 }, 825 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ 826 }; 827