2 * ntp_restrict.c - determine host restrictions
13 #include "ntp_lists.h"
14 #include "ntp_stdlib.h"
15 #include "ntp_assert.h"
18 * This code keeps a simple address-and-mask list of hosts we want
19 * to place restrictions on (or remove them from). The restrictions
20 * are implemented as a set of flags which tell you what the host
21 * can't do. There is a subroutine entry to return the flags. The
22 * list is kept sorted to reduce the average number of comparisons
23 * and make sure you get the set of restrictions most specific to
26 * The algorithm is that, when looking up a host, it is first assumed
27 * that the default set of restrictions will apply. It then searches
28 * down through the list. Whenever it finds a match it adopts the
29 * match's flags instead. When you hit the point where the sorted
30 * address is greater than the target, you return with the last set of
31 * flags you found. Because of the ordering of the list, the most
32 * specific match will provide the final set of flags.
34 * This was originally intended to restrict you from sync'ing to your
35 * own broadcasts when you are doing that, by restricting yourself from
36 * your own interfaces. It was also thought it would sometimes be useful
37 * to keep a misbehaving host or two from abusing your primary clock. It
38 * has been expanded, however, to suit the needs of those with more
39 * restrictive access policies.
42 * We will use two lists, one for IPv4 addresses and one for IPv6
43 * addresses. This is not protocol-independant but for now I can't
44 * find a way to respect this. We'll check this later... JFB 07/2001
46 #define MASK_IPV6_ADDR(dst, src, msk) \
49 for (idx = 0; idx < (int)COUNTOF((dst)->s6_addr); idx++) { \
50 (dst)->s6_addr[idx] = (src)->s6_addr[idx] \
51 & (msk)->s6_addr[idx]; \
56 * We allocate INC_RESLIST{4|6} entries to the free list whenever empty.
57 * Auto-tune these to be just less than 1KB (leaving at least 16 bytes
58 * for allocator overhead).
60 #define INC_RESLIST4 ((1024 - 16) / V4_SIZEOF_RESTRICT_U)
61 #define INC_RESLIST6 ((1024 - 16) / V6_SIZEOF_RESTRICT_U)
64 * The restriction list
66 restrict_u *restrictlist4;
67 restrict_u *restrictlist6;
68 static int restrictcount; /* count in the restrict lists */
71 * The free list and associated counters. Also some uninteresting
74 static restrict_u *resfree4; /* available entries (free list) */
75 static restrict_u *resfree6;
77 static u_long res_calls;
78 static u_long res_found;
79 static u_long res_not_found;
82 * Count number of restriction entries referring to RES_LIMITED, to
83 * control implicit activation/deactivation of the MRU monlist.
85 static u_long res_limited_refcnt;
88 * Our default entries.
90 * We can make this cleaner with c99 support: see init_restrict().
92 static restrict_u restrict_def4;
93 static restrict_u restrict_def6;
96 * "restrict source ..." enabled knob and restriction bits.
98 static int restrict_source_enabled;
99 static u_int32 restrict_source_rflags;
100 static u_short restrict_source_mflags;
101 static short restrict_source_ippeerlimit;
106 static restrict_u * alloc_res4(void);
107 static restrict_u * alloc_res6(void);
108 static void free_res(restrict_u *, int);
109 static void inc_res_limited(void);
110 static void dec_res_limited(void);
111 static restrict_u * match_restrict4_addr(u_int32, u_short);
112 static restrict_u * match_restrict6_addr(const struct in6_addr *,
114 static restrict_u * match_restrict_entry(const restrict_u *, int);
115 static int res_sorts_before4(restrict_u *, restrict_u *);
116 static int res_sorts_before6(restrict_u *, restrict_u *);
117 static char * roptoa(restrict_op op);
120 void dump_restricts(void);
123 * dump_restrict - spit out a restrict_u
131 char as[INET6_ADDRSTRLEN];
132 char ms[INET6_ADDRSTRLEN];
135 inet_ntop(AF_INET6, &res->u.v6.addr, as, sizeof as);
136 inet_ntop(AF_INET6, &res->u.v6.mask, ms, sizeof ms);
138 struct in_addr sia = { htonl(res->u.v4.addr) };
139 struct in_addr sim = { htonl(res->u.v4.mask) };
141 inet_ntop(AF_INET, &sia, as, sizeof as);
142 inet_ntop(AF_INET, &sim, ms, sizeof ms);
144 mprintf("restrict node at %p: %s/%s count %d, rflags %08x, mflags %04x, ippeerlimit %d, expire %lu, next %p\n",
145 res, as, ms, res->count, res->rflags, res->mflags,
146 res->ippeerlimit, res->expire, res->link);
152 * dump_restricts - spit out the 'restrict' lines
160 mprintf("dump_restrict: restrict_def4: %p\n", &restrict_def4);
161 /* Spit out 'restrict {,-4,-6} default ...' lines, if needed */
162 for (res = &restrict_def4; res != NULL; res = next) {
163 dump_restrict(res, 0);
167 mprintf("dump_restrict: restrict_def6: %p\n", &restrict_def6);
168 for (res = &restrict_def6; res != NULL; res = next) {
169 dump_restrict(res, 1);
173 /* Spit out the IPv4 list */
174 mprintf("dump_restrict: restrictlist4: %p\n", &restrictlist4);
175 for (res = restrictlist4; res != NULL; res = next) {
176 dump_restrict(res, 0);
180 /* Spit out the IPv6 list */
181 mprintf("dump_restrict: restrictlist6: %p\n", &restrictlist6);
182 for (res = restrictlist6; res != NULL; res = next) {
183 dump_restrict(res, 1);
191 * init_restrict - initialize the restriction data structures
197 * The restriction lists begin with a default entry with address
198 * and mask 0, which will match any entry. The lists are kept
199 * sorted by descending address followed by descending mask:
202 * 192.168.0.0 255.255.255.0 kod limited noquery nopeer
203 * 192.168.0.0 255.255.0.0 kod limited
204 * 0.0.0.0 0.0.0.0 kod limited noquery
206 * The first entry which matches an address is used. With the
207 * example restrictions above, 192.168.0.0/24 matches the first
208 * entry, the rest of 192.168.0.0/16 matches the second, and
209 * everything else matches the third (default).
211 * Note this achieves the same result a little more efficiently
212 * than the documented behavior, which is to keep the lists
213 * sorted by ascending address followed by ascending mask, with
214 * the _last_ matching entry used.
216 * An additional wrinkle is we may have multiple entries with
217 * the same address and mask but differing match flags (mflags).
218 * At present there is only one, RESM_NTPONLY. Entries with
219 * RESM_NTPONLY are sorted earlier so they take precedence over
220 * any otherwise similar entry without. Again, this is the same
221 * behavior as but reversed implementation compared to the docs.
225 restrict_def4.ippeerlimit = -1; /* Cleaner if we have C99 */
226 restrict_def6.ippeerlimit = -1; /* Cleaner if we have C99 */
228 LINK_SLIST(restrictlist4, &restrict_def4, link);
229 LINK_SLIST(restrictlist6, &restrict_def6, link);
237 const size_t cb = V4_SIZEOF_RESTRICT_U;
238 const size_t count = INC_RESLIST4;
243 UNLINK_HEAD_SLIST(res, resfree4, link);
247 rl = eallocarray(count, cb);
248 /* link all but the first onto free list */
249 res = (void *)((char *)rl + (count - 1) * cb);
250 for (i = count - 1; i > 0; i--) {
251 LINK_SLIST(resfree4, res, link);
252 res = (void *)((char *)res - cb);
255 /* allocate the first */
263 const size_t cb = V6_SIZEOF_RESTRICT_U;
264 const size_t count = INC_RESLIST6;
269 UNLINK_HEAD_SLIST(res, resfree6, link);
273 rl = eallocarray(count, cb);
274 /* link all but the first onto free list */
275 res = (void *)((char *)rl + (count - 1) * cb);
276 for (i = count - 1; i > 0; i--) {
277 LINK_SLIST(resfree6, res, link);
278 res = (void *)((char *)res - cb);
281 /* allocate the first */
292 restrict_u ** plisthead;
293 restrict_u * unlinked;
296 if (RES_LIMITED & res->rflags)
300 plisthead = &restrictlist6;
302 plisthead = &restrictlist4;
303 UNLINK_SLIST(unlinked, *plisthead, res, link, restrict_u);
304 INSIST(unlinked == res);
307 zero_mem(res, V6_SIZEOF_RESTRICT_U);
308 plisthead = &resfree6;
310 zero_mem(res, V4_SIZEOF_RESTRICT_U);
311 plisthead = &resfree4;
313 LINK_SLIST(*plisthead, res, link);
318 inc_res_limited(void)
320 if (!res_limited_refcnt)
322 res_limited_refcnt++;
327 dec_res_limited(void)
329 res_limited_refcnt--;
330 if (!res_limited_refcnt)
336 match_restrict4_addr(
345 for (res = restrictlist4; res != NULL; res = next) {
346 struct in_addr sia = { htonl(res->u.v4.addr) };
349 DPRINTF(2, ("match_restrict4_addr: Checking %s, port %d ... ",
350 inet_ntoa(sia), port));
352 && res->expire <= current_time)
353 free_res(res, v6); /* zeroes the contents */
354 if ( res->u.v4.addr == (addr & res->u.v4.mask)
355 && ( !(RESM_NTPONLY & res->mflags)
356 || NTP_PORT == port)) {
357 DPRINTF(2, ("MATCH: ippeerlimit %d\n", res->ippeerlimit));
360 DPRINTF(2, ("doesn't match: ippeerlimit %d\n", res->ippeerlimit));
367 match_restrict6_addr(
368 const struct in6_addr * addr,
375 struct in6_addr masked;
377 for (res = restrictlist6; res != NULL; res = next) {
381 res->expire <= current_time)
383 MASK_IPV6_ADDR(&masked, addr, &res->u.v6.mask);
384 if (ADDR6_EQ(&masked, &res->u.v6.addr)
385 && (!(RESM_NTPONLY & res->mflags)
386 || NTP_PORT == (int)port))
394 * match_restrict_entry - find an exact match on a restrict list.
396 * Exact match is addr, mask, and mflags all equal.
397 * In order to use more common code for IPv4 and IPv6, this routine
398 * requires the caller to populate a restrict_u with mflags and either
399 * the v4 or v6 address and mask as appropriate. Other fields in the
400 * input restrict_u are ignored.
403 match_restrict_entry(
404 const restrict_u * pmatch,
413 rlist = restrictlist6;
414 cb = sizeof(pmatch->u.v6);
416 rlist = restrictlist4;
417 cb = sizeof(pmatch->u.v4);
420 for (res = rlist; res != NULL; res = res->link)
421 if (res->mflags == pmatch->mflags &&
422 !memcmp(&res->u, &pmatch->u, cb))
429 * res_sorts_before4 - compare two restrict4 entries
431 * Returns nonzero if r1 sorts before r2. We sort by descending
432 * address, then descending mask, then descending mflags, so sorting
433 * before means having a higher value.
443 if (r1->u.v4.addr > r2->u.v4.addr)
445 else if (r1->u.v4.addr < r2->u.v4.addr)
447 else if (r1->u.v4.mask > r2->u.v4.mask)
449 else if (r1->u.v4.mask < r2->u.v4.mask)
451 else if (r1->mflags > r2->mflags)
461 * res_sorts_before6 - compare two restrict6 entries
463 * Returns nonzero if r1 sorts before r2. We sort by descending
464 * address, then descending mask, then descending mflags, so sorting
465 * before means having a higher value.
476 cmp = ADDR6_CMP(&r1->u.v6.addr, &r2->u.v6.addr);
477 if (cmp > 0) /* r1->addr > r2->addr */
479 else if (cmp < 0) /* r2->addr > r1->addr */
482 cmp = ADDR6_CMP(&r1->u.v6.mask, &r2->u.v6.mask);
483 if (cmp > 0) /* r1->mask > r2->mask*/
485 else if (cmp < 0) /* r2->mask > r1->mask */
487 else if (r1->mflags > r2->mflags)
498 * restrictions - return restrictions for this host in *r4a
507 struct in6_addr *pin6;
509 REQUIRE(NULL != r4a);
512 r4a->rflags = RES_IGNORE;
513 r4a->ippeerlimit = 0;
515 DPRINTF(1, ("restrictions: looking up %s\n", stoa(srcadr)));
517 /* IPv4 source address */
518 if (IS_IPV4(srcadr)) {
520 * Ignore any packets with a multicast source address
521 * (this should be done early in the receive process,
524 if (IN_CLASSD(SRCADR(srcadr))) {
525 DPRINTF(1, ("restrictions: srcadr %s is multicast\n", stoa(srcadr)));
526 r4a->ippeerlimit = 2; /* XXX: we should use a better value */
530 match = match_restrict4_addr(SRCADR(srcadr),
533 INSIST(match != NULL);
537 * res_not_found counts only use of the final default
538 * entry, not any "restrict default ntpport ...", which
539 * would be just before the final default.
541 if (&restrict_def4 == match)
545 r4a->rflags = match->rflags;
546 r4a->ippeerlimit = match->ippeerlimit;
549 /* IPv6 source address */
550 if (IS_IPV6(srcadr)) {
551 pin6 = PSOCK_ADDR6(srcadr);
554 * Ignore any packets with a multicast source address
555 * (this should be done early in the receive process,
558 if (IN6_IS_ADDR_MULTICAST(pin6))
561 match = match_restrict6_addr(pin6, SRCPORT(srcadr));
562 INSIST(match != NULL);
564 if (&restrict_def6 == match)
568 r4a->rflags = match->rflags;
569 r4a->ippeerlimit = match->ippeerlimit;
577 * roptoa - convert a restrict_op to a string
580 roptoa(restrict_op op) {
584 case RESTRICT_FLAGS: return "RESTRICT_FLAGS";
585 case RESTRICT_UNFLAG: return "RESTRICT_UNFLAGS";
586 case RESTRICT_REMOVE: return "RESTRICT_REMOVE";
587 case RESTRICT_REMOVEIF: return "RESTRICT_REMOVEIF";
589 snprintf(sb, sizeof sb, "**RESTRICT_#%d**", op);
596 * hack_restrict - add/subtract/manipulate entries on the restrict list
601 sockaddr_u * resaddr,
602 sockaddr_u * resmask,
612 restrict_u ** plisthead;
614 DPRINTF(1, ("hack_restrict: op %s addr %s mask %s ippeerlimit %d mflags %08x rflags %08x\n",
615 roptoa(op), stoa(resaddr), stoa(resmask), ippeerlimit, mflags, rflags));
617 if (NULL == resaddr) {
618 REQUIRE(NULL == resmask);
619 REQUIRE(RESTRICT_FLAGS == op);
620 restrict_source_rflags = rflags;
621 restrict_source_mflags = mflags;
622 restrict_source_ippeerlimit = ippeerlimit;
623 restrict_source_enabled = 1;
630 /* silence VC9 potentially uninit warnings */
631 // HMS: let's use a compiler-specific "enable" for this.
636 if (IS_IPV4(resaddr)) {
639 * Get address and mask in host byte order for easy
640 * comparison as u_int32
642 match.u.v4.addr = SRCADR(resaddr);
643 match.u.v4.mask = SRCADR(resmask);
644 match.u.v4.addr &= match.u.v4.mask;
646 } else if (IS_IPV6(resaddr)) {
649 * Get address and mask in network byte order for easy
650 * comparison as byte sequences (e.g. memcmp())
652 match.u.v6.mask = SOCK_ADDR6(resmask);
653 MASK_IPV6_ADDR(&match.u.v6.addr, PSOCK_ADDR6(resaddr),
656 } else /* not IPv4 nor IPv6 */
659 match.rflags = rflags;
660 match.mflags = mflags;
661 match.ippeerlimit = ippeerlimit;
662 match.expire = expire;
663 res = match_restrict_entry(&match, v6);
669 * Here we add bits to the rflags. If this is a
670 * new restriction add it.
676 V6_SIZEOF_RESTRICT_U);
677 plisthead = &restrictlist6;
681 V4_SIZEOF_RESTRICT_U);
682 plisthead = &restrictlist4;
687 ? res_sorts_before6(res, L_S_S_CUR())
688 : res_sorts_before4(res, L_S_S_CUR()),
691 if (RES_LIMITED & rflags)
694 if ( (RES_LIMITED & rflags)
695 && !(RES_LIMITED & res->rflags))
697 res->rflags |= rflags;
700 res->ippeerlimit = match.ippeerlimit;
704 case RESTRICT_UNFLAG:
706 * Remove some bits from the rflags. If we didn't
707 * find this one, just return.
710 if ( (RES_LIMITED & res->rflags)
711 && (RES_LIMITED & rflags))
713 res->rflags &= ~rflags;
717 case RESTRICT_REMOVE:
718 case RESTRICT_REMOVEIF:
720 * Remove an entry from the table entirely if we
721 * found one. Don't remove the default entry and
722 * don't remove an interface entry.
725 && (RESTRICT_REMOVEIF == op
726 || !(RESM_INTERFACE & res->mflags))
727 && res != &restrict_def4
728 && res != &restrict_def6)
732 default: /* unknown op */
741 * restrict_source - maintains dynamic "restrict source ..." entries as
747 int farewell, /* 0 to add, 1 to remove */
748 u_long expire /* 0 is infinite, valid until */
755 if (!restrict_source_enabled || SOCK_UNSPEC(addr) ||
756 IS_MCAST(addr) || ISREFCLOCKADR(addr))
759 REQUIRE(AF_INET == AF(addr) || AF_INET6 == AF(addr));
761 SET_HOSTMASK(&onesmask, AF(addr));
763 hack_restrict(RESTRICT_REMOVE, addr, &onesmask,
765 DPRINTF(1, ("restrict_source: %s removed", stoa(addr)));
770 * If there is a specific entry for this address, hands
771 * off, as it is condidered more specific than "restrict
773 * However, if the specific entry found is a fleeting one
774 * added by pool_xmit() before soliciting, replace it
775 * immediately regardless of the expire value to make way
776 * for the more persistent entry.
779 res = match_restrict4_addr(SRCADR(addr), SRCPORT(addr));
781 found_specific = (SRCADR(&onesmask) == res->u.v4.mask);
783 res = match_restrict6_addr(&SOCK_ADDR6(addr),
786 found_specific = ADDR6_EQ(&res->u.v6.mask,
787 &SOCK_ADDR6(&onesmask));
789 if (!expire && found_specific && res->expire) {
791 free_res(res, IS_IPV6(addr));
796 hack_restrict(RESTRICT_FLAGS, addr, &onesmask,
797 restrict_source_ippeerlimit,
798 restrict_source_mflags, restrict_source_rflags, expire);
799 DPRINTF(1, ("restrict_source: %s host restriction added\n",