ntp_restrict.c revision 293894
159191Skris/* 259191Skris * ntp_restrict.c - determine host restrictions 359191Skris */ 459191Skris#ifdef HAVE_CONFIG_H 559191Skris#include <config.h> 659191Skris#endif 759191Skris 8296465Sdelphij#include <stdio.h> 959191Skris#include <sys/types.h> 1059191Skris 1159191Skris#include "ntpd.h" 1259191Skris#include "ntp_if.h" 1359191Skris#include "ntp_lists.h" 1459191Skris#include "ntp_stdlib.h" 15296465Sdelphij#include "ntp_assert.h" 1659191Skris 1759191Skris/* 1859191Skris * This code keeps a simple address-and-mask list of hosts we want 1959191Skris * to place restrictions on (or remove them from). The restrictions 2059191Skris * are implemented as a set of flags which tell you what the host 2159191Skris * can't do. There is a subroutine entry to return the flags. The 22296465Sdelphij * list is kept sorted to reduce the average number of comparisons 2359191Skris * and make sure you get the set of restrictions most specific to 2459191Skris * the address. 2559191Skris * 2659191Skris * The algorithm is that, when looking up a host, it is first assumed 2759191Skris * that the default set of restrictions will apply. It then searches 2859191Skris * down through the list. Whenever it finds a match it adopts the 2959191Skris * match's flags instead. When you hit the point where the sorted 3059191Skris * address is greater than the target, you return with the last set of 3159191Skris * flags you found. Because of the ordering of the list, the most 3259191Skris * specific match will provide the final set of flags. 3359191Skris * 3459191Skris * This was originally intended to restrict you from sync'ing to your 3559191Skris * own broadcasts when you are doing that, by restricting yourself from 3659191Skris * your own interfaces. It was also thought it would sometimes be useful 37296465Sdelphij * to keep a misbehaving host or two from abusing your primary clock. It 3859191Skris * has been expanded, however, to suit the needs of those with more 3959191Skris * restrictive access policies. 40296465Sdelphij */ 4159191Skris/* 4259191Skris * We will use two lists, one for IPv4 addresses and one for IPv6 4359191Skris * addresses. This is not protocol-independant but for now I can't 4459191Skris * find a way to respect this. We'll check this later... JFB 07/2001 4559191Skris */ 4659191Skris#define MASK_IPV6_ADDR(dst, src, msk) \ 4759191Skris do { \ 4859191Skris int idx; \ 4959191Skris for (idx = 0; idx < (int)COUNTOF((dst)->s6_addr); idx++) { \ 5059191Skris (dst)->s6_addr[idx] = (src)->s6_addr[idx] \ 5159191Skris & (msk)->s6_addr[idx]; \ 52296465Sdelphij } \ 5359191Skris } while (0) 5459191Skris 5559191Skris/* 5659191Skris * We allocate INC_RESLIST{4|6} entries to the free list whenever empty. 5759191Skris * Auto-tune these to be just less than 1KB (leaving at least 16 bytes 5859191Skris * for allocator overhead). 5959191Skris */ 6059191Skris#define INC_RESLIST4 ((1024 - 16) / V4_SIZEOF_RESTRICT_U) 6159191Skris#define INC_RESLIST6 ((1024 - 16) / V6_SIZEOF_RESTRICT_U) 6259191Skris 6359191Skris/* 6459191Skris * The restriction list 6559191Skris */ 66296465Sdelphijrestrict_u *restrictlist4; 67100936Snectarrestrict_u *restrictlist6; 68109998Smarkmstatic int restrictcount; /* count in the restrict lists */ 69296465Sdelphij 70296465Sdelphij/* 71296465Sdelphij * The free list and associated counters. Also some uninteresting 72296465Sdelphij * stat counters. 73296465Sdelphij */ 74296465Sdelphijstatic restrict_u *resfree4; /* available entries (free list) */ 75296465Sdelphijstatic restrict_u *resfree6; 7659191Skris 77296465Sdelphijstatic u_long res_calls; 78296465Sdelphijstatic u_long res_found; 79296465Sdelphijstatic u_long res_not_found; 8059191Skris 81296465Sdelphij/* 82296465Sdelphij * Count number of restriction entries referring to RES_LIMITED, to 83296465Sdelphij * control implicit activation/deactivation of the MRU monlist. 8459191Skris */ 85296465Sdelphijstatic u_long res_limited_refcnt; 86296465Sdelphij 87296465Sdelphij/* 88296465Sdelphij * Our default entries. 89296465Sdelphij */ 90296465Sdelphijstatic restrict_u restrict_def4; 91296465Sdelphijstatic restrict_u restrict_def6; 9259191Skris 93296465Sdelphij/* 94296465Sdelphij * "restrict source ..." enabled knob and restriction bits. 95296465Sdelphij */ 9659191Skrisstatic int restrict_source_enabled; 9759191Skrisstatic u_short restrict_source_flags; 98109998Smarkmstatic u_short restrict_source_mflags; 99296465Sdelphij 100296465Sdelphij/* 10159191Skris * private functions 10259191Skris */ 103109998Smarkmstatic restrict_u * alloc_res4(void); 104296465Sdelphijstatic restrict_u * alloc_res6(void); 105296465Sdelphijstatic void free_res(restrict_u *, int); 106296465Sdelphijstatic void inc_res_limited(void); 107296465Sdelphijstatic void dec_res_limited(void); 108296465Sdelphijstatic restrict_u * match_restrict4_addr(u_int32, u_short); 109296465Sdelphijstatic restrict_u * match_restrict6_addr(const struct in6_addr *, 11059191Skris u_short); 11159191Skrisstatic restrict_u * match_restrict_entry(const restrict_u *, int); 112194206Ssimonstatic int res_sorts_before4(restrict_u *, restrict_u *); 113296465Sdelphijstatic int res_sorts_before6(restrict_u *, restrict_u *); 114296465Sdelphij 115296465Sdelphij 116296465Sdelphij/* 117296465Sdelphij * init_restrict - initialize the restriction data structures 118296465Sdelphij */ 119194206Ssimonvoid 120194206Ssimoninit_restrict(void) 121109998Smarkm{ 122296465Sdelphij /* 123296465Sdelphij * The restriction lists begin with a default entry with address 124296465Sdelphij * and mask 0, which will match any entry. The lists are kept 125296465Sdelphij * sorted by descending address followed by descending mask: 126296465Sdelphij * 127296465Sdelphij * address mask 128296465Sdelphij * 192.168.0.0 255.255.255.0 kod limited noquery nopeer 129296465Sdelphij * 192.168.0.0 255.255.0.0 kod limited 13059191Skris * 0.0.0.0 0.0.0.0 kod limited noquery 13159191Skris * 132109998Smarkm * The first entry which matches an address is used. With the 133296465Sdelphij * example restrictions above, 192.168.0.0/24 matches the first 134296465Sdelphij * entry, the rest of 192.168.0.0/16 matches the second, and 135296465Sdelphij * everything else matches the third (default). 136296465Sdelphij * 137296465Sdelphij * Note this achieves the same result a little more efficiently 138296465Sdelphij * than the documented behavior, which is to keep the lists 139296465Sdelphij * sorted by ascending address followed by ascending mask, with 14059191Skris * the _last_ matching entry used. 14159191Skris * 142109998Smarkm * An additional wrinkle is we may have multiple entries with 143296465Sdelphij * the same address and mask but differing match flags (mflags). 144296465Sdelphij * At present there is only one, RESM_NTPONLY. Entries with 145296465Sdelphij * RESM_NTPONLY are sorted earlier so they take precedence over 146296465Sdelphij * any otherwise similar entry without. Again, this is the same 147296465Sdelphij * behavior as but reversed implementation compared to the docs. 148296465Sdelphij * 149296465Sdelphij */ 150296465Sdelphij LINK_SLIST(restrictlist4, &restrict_def4, link); 15159191Skris LINK_SLIST(restrictlist6, &restrict_def6, link); 15259191Skris restrictcount = 2; 153109998Smarkm} 154296465Sdelphij 155296465Sdelphij 156296465Sdelphijstatic restrict_u * 157296465Sdelphijalloc_res4(void) 158296465Sdelphij{ 159296465Sdelphij const size_t cb = V4_SIZEOF_RESTRICT_U; 16059191Skris const size_t count = INC_RESLIST4; 161109998Smarkm restrict_u * rl; 162109998Smarkm restrict_u * res; 163296465Sdelphij size_t i; 164296465Sdelphij 165296465Sdelphij UNLINK_HEAD_SLIST(res, resfree4, link); 166296465Sdelphij if (res != NULL) 167296465Sdelphij return res; 168296465Sdelphij 169296465Sdelphij rl = emalloc_zero(count * cb); 170296465Sdelphij /* link all but the first onto free list */ 171296465Sdelphij res = (void *)((char *)rl + (count - 1) * cb); 172296465Sdelphij for (i = count - 1; i > 0; i--) { 173296465Sdelphij LINK_SLIST(resfree4, res, link); 174296465Sdelphij res = (void *)((char *)res - cb); 175296465Sdelphij } 176296465Sdelphij INSIST(rl == res); 177296465Sdelphij /* allocate the first */ 178296465Sdelphij return res; 179296465Sdelphij} 180296465Sdelphij 181296465Sdelphij 182296465Sdelphijstatic restrict_u * 183296465Sdelphijalloc_res6(void) 184296465Sdelphij{ 185296465Sdelphij const size_t cb = V6_SIZEOF_RESTRICT_U; 186296465Sdelphij const size_t count = INC_RESLIST6; 187296465Sdelphij restrict_u * rl; 188296465Sdelphij restrict_u * res; 189296465Sdelphij size_t i; 190296465Sdelphij 191296465Sdelphij UNLINK_HEAD_SLIST(res, resfree6, link); 192296465Sdelphij if (res != NULL) 193296465Sdelphij return res; 194296465Sdelphij 195296465Sdelphij rl = emalloc_zero(count * cb); 196109998Smarkm /* link all but the first onto free list */ 197162911Ssimon res = (void *)((char *)rl + (count - 1) * cb); 198162911Ssimon for (i = count - 1; i > 0; i--) { 199296465Sdelphij LINK_SLIST(resfree6, res, link); 200296465Sdelphij res = (void *)((char *)res - cb); 201296465Sdelphij } 202296465Sdelphij INSIST(rl == res); 203296465Sdelphij /* allocate the first */ 204296465Sdelphij return res; 205296465Sdelphij} 206296465Sdelphij 207296465Sdelphij 208296465Sdelphijstatic void 209296465Sdelphijfree_res( 210296465Sdelphij restrict_u * res, 211296465Sdelphij int v6 212296465Sdelphij ) 213296465Sdelphij{ 214296465Sdelphij restrict_u ** plisthead; 215296465Sdelphij restrict_u * unlinked; 216296465Sdelphij 217296465Sdelphij restrictcount--; 218296465Sdelphij if (RES_LIMITED & res->flags) 219296465Sdelphij dec_res_limited(); 220296465Sdelphij 221296465Sdelphij if (v6) 222296465Sdelphij plisthead = &restrictlist6; 223162911Ssimon else 224162911Ssimon plisthead = &restrictlist4; 225296465Sdelphij UNLINK_SLIST(unlinked, *plisthead, res, link, restrict_u); 226296465Sdelphij INSIST(unlinked == res); 227296465Sdelphij 228 if (v6) { 229 zero_mem(res, V6_SIZEOF_RESTRICT_U); 230 plisthead = &resfree6; 231 } else { 232 zero_mem(res, V4_SIZEOF_RESTRICT_U); 233 plisthead = &resfree4; 234 } 235 LINK_SLIST(*plisthead, res, link); 236} 237 238 239static void 240inc_res_limited(void) 241{ 242 if (!res_limited_refcnt) 243 mon_start(MON_RES); 244 res_limited_refcnt++; 245} 246 247 248static void 249dec_res_limited(void) 250{ 251 res_limited_refcnt--; 252 if (!res_limited_refcnt) 253 mon_stop(MON_RES); 254} 255 256 257static restrict_u * 258match_restrict4_addr( 259 u_int32 addr, 260 u_short port 261 ) 262{ 263 const int v6 = 0; 264 restrict_u * res; 265 restrict_u * next; 266 267 for (res = restrictlist4; res != NULL; res = next) { 268 next = res->link; 269 if (res->expire && 270 res->expire <= current_time) 271 free_res(res, v6); 272 if (res->u.v4.addr == (addr & res->u.v4.mask) 273 && (!(RESM_NTPONLY & res->mflags) 274 || NTP_PORT == port)) 275 break; 276 } 277 return res; 278} 279 280 281static restrict_u * 282match_restrict6_addr( 283 const struct in6_addr * addr, 284 u_short port 285 ) 286{ 287 const int v6 = 1; 288 restrict_u * res; 289 restrict_u * next; 290 struct in6_addr masked; 291 292 for (res = restrictlist6; res != NULL; res = next) { 293 next = res->link; 294 INSIST(next != res); 295 if (res->expire && 296 res->expire <= current_time) 297 free_res(res, v6); 298 MASK_IPV6_ADDR(&masked, addr, &res->u.v6.mask); 299 if (ADDR6_EQ(&masked, &res->u.v6.addr) 300 && (!(RESM_NTPONLY & res->mflags) 301 || NTP_PORT == (int)port)) 302 break; 303 } 304 return res; 305} 306 307 308/* 309 * match_restrict_entry - find an exact match on a restrict list. 310 * 311 * Exact match is addr, mask, and mflags all equal. 312 * In order to use more common code for IPv4 and IPv6, this routine 313 * requires the caller to populate a restrict_u with mflags and either 314 * the v4 or v6 address and mask as appropriate. Other fields in the 315 * input restrict_u are ignored. 316 */ 317static restrict_u * 318match_restrict_entry( 319 const restrict_u * pmatch, 320 int v6 321 ) 322{ 323 restrict_u *res; 324 restrict_u *rlist; 325 size_t cb; 326 327 if (v6) { 328 rlist = restrictlist6; 329 cb = sizeof(pmatch->u.v6); 330 } else { 331 rlist = restrictlist4; 332 cb = sizeof(pmatch->u.v4); 333 } 334 335 for (res = rlist; res != NULL; res = res->link) 336 if (res->mflags == pmatch->mflags && 337 !memcmp(&res->u, &pmatch->u, cb)) 338 break; 339 return res; 340} 341 342 343/* 344 * res_sorts_before4 - compare two restrict4 entries 345 * 346 * Returns nonzero if r1 sorts before r2. We sort by descending 347 * address, then descending mask, then descending mflags, so sorting 348 * before means having a higher value. 349 */ 350static int 351res_sorts_before4( 352 restrict_u *r1, 353 restrict_u *r2 354 ) 355{ 356 int r1_before_r2; 357 358 if (r1->u.v4.addr > r2->u.v4.addr) 359 r1_before_r2 = 1; 360 else if (r1->u.v4.addr < r2->u.v4.addr) 361 r1_before_r2 = 0; 362 else if (r1->u.v4.mask > r2->u.v4.mask) 363 r1_before_r2 = 1; 364 else if (r1->u.v4.mask < r2->u.v4.mask) 365 r1_before_r2 = 0; 366 else if (r1->mflags > r2->mflags) 367 r1_before_r2 = 1; 368 else 369 r1_before_r2 = 0; 370 371 return r1_before_r2; 372} 373 374 375/* 376 * res_sorts_before6 - compare two restrict6 entries 377 * 378 * Returns nonzero if r1 sorts before r2. We sort by descending 379 * address, then descending mask, then descending mflags, so sorting 380 * before means having a higher value. 381 */ 382static int 383res_sorts_before6( 384 restrict_u *r1, 385 restrict_u *r2 386 ) 387{ 388 int r1_before_r2; 389 int cmp; 390 391 cmp = ADDR6_CMP(&r1->u.v6.addr, &r2->u.v6.addr); 392 if (cmp > 0) /* r1->addr > r2->addr */ 393 r1_before_r2 = 1; 394 else if (cmp < 0) /* r2->addr > r1->addr */ 395 r1_before_r2 = 0; 396 else { 397 cmp = ADDR6_CMP(&r1->u.v6.mask, &r2->u.v6.mask); 398 if (cmp > 0) /* r1->mask > r2->mask*/ 399 r1_before_r2 = 1; 400 else if (cmp < 0) /* r2->mask > r1->mask */ 401 r1_before_r2 = 0; 402 else if (r1->mflags > r2->mflags) 403 r1_before_r2 = 1; 404 else 405 r1_before_r2 = 0; 406 } 407 408 return r1_before_r2; 409} 410 411 412/* 413 * restrictions - return restrictions for this host 414 */ 415u_short 416restrictions( 417 sockaddr_u *srcadr 418 ) 419{ 420 restrict_u *match; 421 struct in6_addr *pin6; 422 u_short flags; 423 424 res_calls++; 425 flags = 0; 426 /* IPv4 source address */ 427 if (IS_IPV4(srcadr)) { 428 /* 429 * Ignore any packets with a multicast source address 430 * (this should be done early in the receive process, 431 * not later!) 432 */ 433 if (IN_CLASSD(SRCADR(srcadr))) 434 return (int)RES_IGNORE; 435 436 match = match_restrict4_addr(SRCADR(srcadr), 437 SRCPORT(srcadr)); 438 439 INSIST(match != NULL); 440 441 match->count++; 442 /* 443 * res_not_found counts only use of the final default 444 * entry, not any "restrict default ntpport ...", which 445 * would be just before the final default. 446 */ 447 if (&restrict_def4 == match) 448 res_not_found++; 449 else 450 res_found++; 451 flags = match->flags; 452 } 453 454 /* IPv6 source address */ 455 if (IS_IPV6(srcadr)) { 456 pin6 = PSOCK_ADDR6(srcadr); 457 458 /* 459 * Ignore any packets with a multicast source address 460 * (this should be done early in the receive process, 461 * not later!) 462 */ 463 if (IN6_IS_ADDR_MULTICAST(pin6)) 464 return (int)RES_IGNORE; 465 466 match = match_restrict6_addr(pin6, SRCPORT(srcadr)); 467 INSIST(match != NULL); 468 match->count++; 469 if (&restrict_def6 == match) 470 res_not_found++; 471 else 472 res_found++; 473 flags = match->flags; 474 } 475 return (flags); 476} 477 478 479/* 480 * hack_restrict - add/subtract/manipulate entries on the restrict list 481 */ 482void 483hack_restrict( 484 int op, 485 sockaddr_u * resaddr, 486 sockaddr_u * resmask, 487 u_short mflags, 488 u_short flags, 489 u_long expire 490 ) 491{ 492 int v6; 493 restrict_u match; 494 restrict_u * res; 495 restrict_u ** plisthead; 496 497 DPRINTF(1, ("restrict: op %d addr %s mask %s mflags %08x flags %08x\n", 498 op, stoa(resaddr), stoa(resmask), mflags, flags)); 499 500 if (NULL == resaddr) { 501 REQUIRE(NULL == resmask); 502 REQUIRE(RESTRICT_FLAGS == op); 503 restrict_source_flags = flags; 504 restrict_source_mflags = mflags; 505 restrict_source_enabled = 1; 506 return; 507 } 508 509 ZERO(match); 510 511#if 0 512 /* silence VC9 potentially uninit warnings */ 513 // HMS: let's use a compiler-specific "enable" for this. 514 res = NULL; 515 v6 = 0; 516#endif 517 518 if (IS_IPV4(resaddr)) { 519 v6 = 0; 520 /* 521 * Get address and mask in host byte order for easy 522 * comparison as u_int32 523 */ 524 match.u.v4.addr = SRCADR(resaddr); 525 match.u.v4.mask = SRCADR(resmask); 526 match.u.v4.addr &= match.u.v4.mask; 527 528 } else if (IS_IPV6(resaddr)) { 529 v6 = 1; 530 /* 531 * Get address and mask in network byte order for easy 532 * comparison as byte sequences (e.g. memcmp()) 533 */ 534 match.u.v6.mask = SOCK_ADDR6(resmask); 535 MASK_IPV6_ADDR(&match.u.v6.addr, PSOCK_ADDR6(resaddr), 536 &match.u.v6.mask); 537 538 } else /* not IPv4 nor IPv6 */ 539 REQUIRE(0); 540 541 match.flags = flags; 542 match.mflags = mflags; 543 match.expire = expire; 544 res = match_restrict_entry(&match, v6); 545 546 switch (op) { 547 548 case RESTRICT_FLAGS: 549 /* 550 * Here we add bits to the flags. If this is a 551 * new restriction add it. 552 */ 553 if (NULL == res) { 554 if (v6) { 555 res = alloc_res6(); 556 memcpy(res, &match, 557 V6_SIZEOF_RESTRICT_U); 558 plisthead = &restrictlist6; 559 } else { 560 res = alloc_res4(); 561 memcpy(res, &match, 562 V4_SIZEOF_RESTRICT_U); 563 plisthead = &restrictlist4; 564 } 565 LINK_SORT_SLIST( 566 *plisthead, res, 567 (v6) 568 ? res_sorts_before6(res, L_S_S_CUR()) 569 : res_sorts_before4(res, L_S_S_CUR()), 570 link, restrict_u); 571 restrictcount++; 572 if (RES_LIMITED & flags) 573 inc_res_limited(); 574 } else { 575 if ((RES_LIMITED & flags) && 576 !(RES_LIMITED & res->flags)) 577 inc_res_limited(); 578 res->flags |= flags; 579 } 580 break; 581 582 case RESTRICT_UNFLAG: 583 /* 584 * Remove some bits from the flags. If we didn't 585 * find this one, just return. 586 */ 587 if (res != NULL) { 588 if ((RES_LIMITED & res->flags) 589 && (RES_LIMITED & flags)) 590 dec_res_limited(); 591 res->flags &= ~flags; 592 } 593 break; 594 595 case RESTRICT_REMOVE: 596 case RESTRICT_REMOVEIF: 597 /* 598 * Remove an entry from the table entirely if we 599 * found one. Don't remove the default entry and 600 * don't remove an interface entry. 601 */ 602 if (res != NULL 603 && (RESTRICT_REMOVEIF == op 604 || !(RESM_INTERFACE & res->mflags)) 605 && res != &restrict_def4 606 && res != &restrict_def6) 607 free_res(res, v6); 608 break; 609 610 default: /* unknown op */ 611 INSIST(0); 612 break; 613 } 614 615} 616 617 618/* 619 * restrict_source - maintains dynamic "restrict source ..." entries as 620 * peers come and go. 621 */ 622void 623restrict_source( 624 sockaddr_u * addr, 625 int farewell, /* 0 to add, 1 to remove */ 626 u_long expire /* 0 is infinite, valid until */ 627 ) 628{ 629 sockaddr_u onesmask; 630 restrict_u * res; 631 int found_specific; 632 633 if (!restrict_source_enabled || SOCK_UNSPEC(addr) || 634 IS_MCAST(addr) || ISREFCLOCKADR(addr)) 635 return; 636 637 REQUIRE(AF_INET == AF(addr) || AF_INET6 == AF(addr)); 638 639 SET_HOSTMASK(&onesmask, AF(addr)); 640 if (farewell) { 641 hack_restrict(RESTRICT_REMOVE, addr, &onesmask, 642 0, 0, 0); 643 DPRINTF(1, ("restrict_source: %s removed", stoa(addr))); 644 return; 645 } 646 647 /* 648 * If there is a specific entry for this address, hands 649 * off, as it is condidered more specific than "restrict 650 * server ...". 651 * However, if the specific entry found is a fleeting one 652 * added by pool_xmit() before soliciting, replace it 653 * immediately regardless of the expire value to make way 654 * for the more persistent entry. 655 */ 656 if (IS_IPV4(addr)) { 657 res = match_restrict4_addr(SRCADR(addr), SRCPORT(addr)); 658 INSIST(res != NULL); 659 found_specific = (SRCADR(&onesmask) == res->u.v4.mask); 660 } else { 661 res = match_restrict6_addr(&SOCK_ADDR6(addr), 662 SRCPORT(addr)); 663 INSIST(res != NULL); 664 found_specific = ADDR6_EQ(&res->u.v6.mask, 665 &SOCK_ADDR6(&onesmask)); 666 } 667 if (!expire && found_specific && res->expire) { 668 found_specific = 0; 669 free_res(res, IS_IPV6(addr)); 670 } 671 if (found_specific) 672 return; 673 674 hack_restrict(RESTRICT_FLAGS, addr, &onesmask, 675 restrict_source_mflags, restrict_source_flags, 676 expire); 677 DPRINTF(1, ("restrict_source: %s host restriction added\n", 678 stoa(addr))); 679} 680