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-rw-r--r--ntpd/ntp_restrict.c669
1 files changed, 669 insertions, 0 deletions
diff --git a/ntpd/ntp_restrict.c b/ntpd/ntp_restrict.c
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+++ b/ntpd/ntp_restrict.c
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+/*
+ * ntp_restrict.c - determine host restrictions
+ */
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <sys/types.h>
+
+#include "ntpd.h"
+#include "ntp_if.h"
+#include "ntp_lists.h"
+#include "ntp_stdlib.h"
+#include "ntp_assert.h"
+
+/*
+ * This code keeps a simple address-and-mask list of hosts we want
+ * to place restrictions on (or remove them from). The restrictions
+ * are implemented as a set of flags which tell you what the host
+ * can't do. There is a subroutine entry to return the flags. The
+ * list is kept sorted to reduce the average number of comparisons
+ * and make sure you get the set of restrictions most specific to
+ * the address.
+ *
+ * The algorithm is that, when looking up a host, it is first assumed
+ * that the default set of restrictions will apply. It then searches
+ * down through the list. Whenever it finds a match it adopts the
+ * match's flags instead. When you hit the point where the sorted
+ * address is greater than the target, you return with the last set of
+ * flags you found. Because of the ordering of the list, the most
+ * specific match will provide the final set of flags.
+ *
+ * This was originally intended to restrict you from sync'ing to your
+ * own broadcasts when you are doing that, by restricting yourself from
+ * your own interfaces. It was also thought it would sometimes be useful
+ * to keep a misbehaving host or two from abusing your primary clock. It
+ * has been expanded, however, to suit the needs of those with more
+ * restrictive access policies.
+ */
+/*
+ * We will use two lists, one for IPv4 addresses and one for IPv6
+ * addresses. This is not protocol-independant but for now I can't
+ * find a way to respect this. We'll check this later... JFB 07/2001
+ */
+#define MASK_IPV6_ADDR(dst, src, msk) \
+ do { \
+ int idx; \
+ for (idx = 0; idx < COUNTOF((dst)->s6_addr); idx++) { \
+ (dst)->s6_addr[idx] = (src)->s6_addr[idx] \
+ & (msk)->s6_addr[idx]; \
+ } \
+ } while (0)
+
+/*
+ * We allocate INC_RESLIST{4|6} entries to the free list whenever empty.
+ * Auto-tune these to be just less than 1KB (leaving at least 16 bytes
+ * for allocator overhead).
+ */
+#define INC_RESLIST4 ((1024 - 16) / V4_SIZEOF_RESTRICT_U)
+#define INC_RESLIST6 ((1024 - 16) / V6_SIZEOF_RESTRICT_U)
+
+/*
+ * The restriction list
+ */
+restrict_u *restrictlist4;
+restrict_u *restrictlist6;
+static int restrictcount; /* count in the restrict lists */
+
+/*
+ * The free list and associated counters. Also some uninteresting
+ * stat counters.
+ */
+static restrict_u *resfree4; /* available entries (free list) */
+static restrict_u *resfree6;
+
+static u_long res_calls;
+static u_long res_found;
+static u_long res_not_found;
+
+/*
+ * Count number of restriction entries referring to RES_LIMITED, to
+ * control implicit activation/deactivation of the MRU monlist.
+ */
+static u_long res_limited_refcnt;
+
+/*
+ * Our default entries.
+ */
+static restrict_u restrict_def4;
+static restrict_u restrict_def6;
+
+/*
+ * "restrict source ..." enabled knob and restriction bits.
+ */
+static int restrict_source_enabled;
+static u_short restrict_source_flags;
+static u_short restrict_source_mflags;
+
+/*
+ * private functions
+ */
+static restrict_u * alloc_res4(void);
+static restrict_u * alloc_res6(void);
+static void free_res(restrict_u *, int);
+static void inc_res_limited(void);
+static void dec_res_limited(void);
+static restrict_u * match_restrict4_addr(u_int32, u_short);
+static restrict_u * match_restrict6_addr(const struct in6_addr *,
+ u_short);
+static restrict_u * match_restrict_entry(const restrict_u *, int);
+static int res_sorts_before4(restrict_u *, restrict_u *);
+static int res_sorts_before6(restrict_u *, restrict_u *);
+
+
+/*
+ * init_restrict - initialize the restriction data structures
+ */
+void
+init_restrict(void)
+{
+ /*
+ * The restriction lists begin with a default entry with address
+ * and mask 0, which will match any entry. The lists are kept
+ * sorted by descending address followed by descending mask:
+ *
+ * address mask
+ * 192.168.0.0 255.255.255.0 kod limited noquery nopeer
+ * 192.168.0.0 255.255.0.0 kod limited
+ * 0.0.0.0 0.0.0.0 kod limited noquery
+ *
+ * The first entry which matches an address is used. With the
+ * example restrictions above, 192.168.0.0/24 matches the first
+ * entry, the rest of 192.168.0.0/16 matches the second, and
+ * everything else matches the third (default).
+ *
+ * Note this achieves the same result a little more efficiently
+ * than the documented behavior, which is to keep the lists
+ * sorted by ascending address followed by ascending mask, with
+ * the _last_ matching entry used.
+ *
+ * An additional wrinkle is we may have multiple entries with
+ * the same address and mask but differing match flags (mflags).
+ * At present there is only one, RESM_NTPONLY. Entries with
+ * RESM_NTPONLY are sorted earlier so they take precedence over
+ * any otherwise similar entry without. Again, this is the same
+ * behavior as but reversed implementation compared to the docs.
+ *
+ */
+ LINK_SLIST(restrictlist4, &restrict_def4, link);
+ LINK_SLIST(restrictlist6, &restrict_def6, link);
+ restrictcount = 2;
+}
+
+
+static restrict_u *
+alloc_res4(void)
+{
+ const size_t cb = V4_SIZEOF_RESTRICT_U;
+ const size_t count = INC_RESLIST4;
+ restrict_u * rl;
+ restrict_u * res;
+ int i;
+
+ UNLINK_HEAD_SLIST(res, resfree4, link);
+ if (res != NULL)
+ return res;
+
+ rl = emalloc_zero(count * cb);
+ /* link all but the first onto free list */
+ res = (void *)((char *)rl + (count - 1) * cb);
+ for (i = count - 1; i > 0; i--) {
+ LINK_SLIST(resfree4, res, link);
+ res = (void *)((char *)res - cb);
+ }
+ NTP_INSIST(rl == res);
+ /* allocate the first */
+ return res;
+}
+
+
+static restrict_u *
+alloc_res6(void)
+{
+ const size_t cb = V6_SIZEOF_RESTRICT_U;
+ const size_t count = INC_RESLIST6;
+ restrict_u * rl;
+ restrict_u * res;
+ int i;
+
+ UNLINK_HEAD_SLIST(res, resfree6, link);
+ if (res != NULL)
+ return res;
+
+ rl = emalloc_zero(count * cb);
+ /* link all but the first onto free list */
+ res = (void *)((char *)rl + (count - 1) * cb);
+ for (i = count - 1; i > 0; i--) {
+ LINK_SLIST(resfree6, res, link);
+ res = (void *)((char *)res - cb);
+ }
+ NTP_INSIST(rl == res);
+ /* allocate the first */
+ return res;
+}
+
+
+static void
+free_res(
+ restrict_u * res,
+ int v6
+ )
+{
+ restrict_u ** plisthead;
+ restrict_u * unlinked;
+
+ restrictcount--;
+ if (RES_LIMITED & res->flags)
+ dec_res_limited();
+
+ if (v6)
+ plisthead = &restrictlist6;
+ else
+ plisthead = &restrictlist4;
+ UNLINK_SLIST(unlinked, *plisthead, res, link, restrict_u);
+ NTP_INSIST(unlinked == res);
+
+ if (v6) {
+ zero_mem(res, V6_SIZEOF_RESTRICT_U);
+ plisthead = &resfree6;
+ } else {
+ zero_mem(res, V4_SIZEOF_RESTRICT_U);
+ plisthead = &resfree4;
+ }
+ LINK_SLIST(*plisthead, res, link);
+}
+
+
+static void
+inc_res_limited(void)
+{
+ if (!res_limited_refcnt)
+ mon_start(MON_RES);
+ res_limited_refcnt++;
+}
+
+
+static void
+dec_res_limited(void)
+{
+ res_limited_refcnt--;
+ if (!res_limited_refcnt)
+ mon_stop(MON_RES);
+}
+
+
+static restrict_u *
+match_restrict4_addr(
+ u_int32 addr,
+ u_short port
+ )
+{
+ const int v6 = 0;
+ restrict_u * res;
+ restrict_u * next;
+
+ for (res = restrictlist4; res != NULL; res = next) {
+ next = res->link;
+ if (res->expire &&
+ res->expire <= current_time)
+ free_res(res, v6);
+ if (res->u.v4.addr == (addr & res->u.v4.mask)
+ && (!(RESM_NTPONLY & res->mflags)
+ || NTP_PORT == port))
+ break;
+ }
+ return res;
+}
+
+
+static restrict_u *
+match_restrict6_addr(
+ const struct in6_addr * addr,
+ u_short port
+ )
+{
+ const int v6 = 1;
+ restrict_u * res;
+ restrict_u * next;
+ struct in6_addr masked;
+
+ for (res = restrictlist6; res != NULL; res = next) {
+ next = res->link;
+ NTP_INSIST(next != res);
+ if (res->expire &&
+ res->expire <= current_time)
+ free_res(res, v6);
+ MASK_IPV6_ADDR(&masked, addr, &res->u.v6.mask);
+ if (ADDR6_EQ(&masked, &res->u.v6.addr)
+ && (!(RESM_NTPONLY & res->mflags)
+ || NTP_PORT == port))
+ break;
+ }
+ return res;
+}
+
+
+/*
+ * match_restrict_entry - find an exact match on a restrict list.
+ *
+ * Exact match is addr, mask, and mflags all equal.
+ * In order to use more common code for IPv4 and IPv6, this routine
+ * requires the caller to populate a restrict_u with mflags and either
+ * the v4 or v6 address and mask as appropriate. Other fields in the
+ * input restrict_u are ignored.
+ */
+static restrict_u *
+match_restrict_entry(
+ const restrict_u * pmatch,
+ int v6
+ )
+{
+ restrict_u *res;
+ restrict_u *rlist;
+ size_t cb;
+
+ if (v6) {
+ rlist = restrictlist6;
+ cb = sizeof(pmatch->u.v6);
+ } else {
+ rlist = restrictlist4;
+ cb = sizeof(pmatch->u.v4);
+ }
+
+ for (res = rlist; res != NULL; res = res->link)
+ if (res->mflags == pmatch->mflags &&
+ !memcmp(&res->u, &pmatch->u, cb))
+ break;
+ return res;
+}
+
+
+/*
+ * res_sorts_before4 - compare two restrict4 entries
+ *
+ * Returns nonzero if r1 sorts before r2. We sort by descending
+ * address, then descending mask, then descending mflags, so sorting
+ * before means having a higher value.
+ */
+static int
+res_sorts_before4(
+ restrict_u *r1,
+ restrict_u *r2
+ )
+{
+ int r1_before_r2;
+
+ if (r1->u.v4.addr > r2->u.v4.addr)
+ r1_before_r2 = 1;
+ else if (r1->u.v4.addr < r2->u.v4.addr)
+ r1_before_r2 = 0;
+ else if (r1->u.v4.mask > r2->u.v4.mask)
+ r1_before_r2 = 1;
+ else if (r1->u.v4.mask < r2->u.v4.mask)
+ r1_before_r2 = 0;
+ else if (r1->mflags > r2->mflags)
+ r1_before_r2 = 1;
+ else
+ r1_before_r2 = 0;
+
+ return r1_before_r2;
+}
+
+
+/*
+ * res_sorts_before6 - compare two restrict6 entries
+ *
+ * Returns nonzero if r1 sorts before r2. We sort by descending
+ * address, then descending mask, then descending mflags, so sorting
+ * before means having a higher value.
+ */
+static int
+res_sorts_before6(
+ restrict_u *r1,
+ restrict_u *r2
+ )
+{
+ int r1_before_r2;
+ int cmp;
+
+ cmp = ADDR6_CMP(&r1->u.v6.addr, &r2->u.v6.addr);
+ if (cmp > 0) /* r1->addr > r2->addr */
+ r1_before_r2 = 1;
+ else if (cmp < 0) /* r2->addr > r1->addr */
+ r1_before_r2 = 0;
+ else {
+ cmp = ADDR6_CMP(&r1->u.v6.mask, &r2->u.v6.mask);
+ if (cmp > 0) /* r1->mask > r2->mask*/
+ r1_before_r2 = 1;
+ else if (cmp < 0) /* r2->mask > r1->mask */
+ r1_before_r2 = 0;
+ else if (r1->mflags > r2->mflags)
+ r1_before_r2 = 1;
+ else
+ r1_before_r2 = 0;
+ }
+
+ return r1_before_r2;
+}
+
+
+/*
+ * restrictions - return restrictions for this host
+ */
+u_short
+restrictions(
+ sockaddr_u *srcadr
+ )
+{
+ restrict_u *match;
+ struct in6_addr *pin6;
+ u_short flags;
+
+ res_calls++;
+ flags = 0;
+ /* IPv4 source address */
+ if (IS_IPV4(srcadr)) {
+ /*
+ * Ignore any packets with a multicast source address
+ * (this should be done early in the receive process,
+ * not later!)
+ */
+ if (IN_CLASSD(SRCADR(srcadr)))
+ return (int)RES_IGNORE;
+
+ match = match_restrict4_addr(SRCADR(srcadr),
+ SRCPORT(srcadr));
+ match->count++;
+ /*
+ * res_not_found counts only use of the final default
+ * entry, not any "restrict default ntpport ...", which
+ * would be just before the final default.
+ */
+ if (&restrict_def4 == match)
+ res_not_found++;
+ else
+ res_found++;
+ flags = match->flags;
+ }
+
+ /* IPv6 source address */
+ if (IS_IPV6(srcadr)) {
+ pin6 = PSOCK_ADDR6(srcadr);
+
+ /*
+ * Ignore any packets with a multicast source address
+ * (this should be done early in the receive process,
+ * not later!)
+ */
+ if (IN6_IS_ADDR_MULTICAST(pin6))
+ return (int)RES_IGNORE;
+
+ match = match_restrict6_addr(pin6, SRCPORT(srcadr));
+ match->count++;
+ if (&restrict_def6 == match)
+ res_not_found++;
+ else
+ res_found++;
+ flags = match->flags;
+ }
+ return (flags);
+}
+
+
+/*
+ * hack_restrict - add/subtract/manipulate entries on the restrict list
+ */
+void
+hack_restrict(
+ int op,
+ sockaddr_u * resaddr,
+ sockaddr_u * resmask,
+ u_short mflags,
+ u_short flags,
+ u_long expire
+ )
+{
+ int v6;
+ restrict_u match;
+ restrict_u * res;
+ restrict_u ** plisthead;
+
+ DPRINTF(1, ("restrict: op %d addr %s mask %s mflags %08x flags %08x\n",
+ op, stoa(resaddr), stoa(resmask), mflags, flags));
+
+ if (NULL == resaddr) {
+ NTP_REQUIRE(NULL == resmask);
+ NTP_REQUIRE(RESTRICT_FLAGS == op);
+ restrict_source_flags = flags;
+ restrict_source_mflags = mflags;
+ restrict_source_enabled = 1;
+ return;
+ }
+
+ ZERO(match);
+ /* silence VC9 potentially uninit warnings */
+ res = NULL;
+ v6 = 0;
+
+ if (IS_IPV4(resaddr)) {
+ v6 = 0;
+ /*
+ * Get address and mask in host byte order for easy
+ * comparison as u_int32
+ */
+ match.u.v4.addr = SRCADR(resaddr);
+ match.u.v4.mask = SRCADR(resmask);
+ match.u.v4.addr &= match.u.v4.mask;
+
+ } else if (IS_IPV6(resaddr)) {
+ v6 = 1;
+ /*
+ * Get address and mask in network byte order for easy
+ * comparison as byte sequences (e.g. memcmp())
+ */
+ match.u.v6.mask = SOCK_ADDR6(resmask);
+ MASK_IPV6_ADDR(&match.u.v6.addr, PSOCK_ADDR6(resaddr),
+ &match.u.v6.mask);
+
+ } else /* not IPv4 nor IPv6 */
+ NTP_REQUIRE(0);
+
+ match.flags = flags;
+ match.mflags = mflags;
+ match.expire = expire;
+ res = match_restrict_entry(&match, v6);
+
+ switch (op) {
+
+ case RESTRICT_FLAGS:
+ /*
+ * Here we add bits to the flags. If this is a
+ * new restriction add it.
+ */
+ if (NULL == res) {
+ if (v6) {
+ res = alloc_res6();
+ memcpy(res, &match,
+ V6_SIZEOF_RESTRICT_U);
+ plisthead = &restrictlist6;
+ } else {
+ res = alloc_res4();
+ memcpy(res, &match,
+ V4_SIZEOF_RESTRICT_U);
+ plisthead = &restrictlist4;
+ }
+ LINK_SORT_SLIST(
+ *plisthead, res,
+ (v6)
+ ? res_sorts_before6(res, L_S_S_CUR())
+ : res_sorts_before4(res, L_S_S_CUR()),
+ link, restrict_u);
+ restrictcount++;
+ if (RES_LIMITED & flags)
+ inc_res_limited();
+ } else {
+ if ((RES_LIMITED & flags) &&
+ !(RES_LIMITED & res->flags))
+ inc_res_limited();
+ res->flags |= flags;
+ }
+ break;
+
+ case RESTRICT_UNFLAG:
+ /*
+ * Remove some bits from the flags. If we didn't
+ * find this one, just return.
+ */
+ if (res != NULL) {
+ if ((RES_LIMITED & res->flags)
+ && (RES_LIMITED & flags))
+ dec_res_limited();
+ res->flags &= ~flags;
+ }
+ break;
+
+ case RESTRICT_REMOVE:
+ case RESTRICT_REMOVEIF:
+ /*
+ * Remove an entry from the table entirely if we
+ * found one. Don't remove the default entry and
+ * don't remove an interface entry.
+ */
+ if (res != NULL
+ && (RESTRICT_REMOVEIF == op
+ || !(RESM_INTERFACE & res->mflags))
+ && res != &restrict_def4
+ && res != &restrict_def6)
+ free_res(res, v6);
+ break;
+
+ default: /* unknown op */
+ NTP_INSIST(0);
+ break;
+ }
+
+}
+
+
+/*
+ * restrict_source - maintains dynamic "restrict source ..." entries as
+ * peers come and go.
+ */
+void
+restrict_source(
+ sockaddr_u * addr,
+ int farewell, /* 0 to add, 1 to remove */
+ u_long expire /* 0 is infinite, valid until */
+ )
+{
+ sockaddr_u onesmask;
+ restrict_u * res;
+ int found_specific;
+
+ if (!restrict_source_enabled || SOCK_UNSPEC(addr) ||
+ IS_MCAST(addr) || ISREFCLOCKADR(addr))
+ return;
+
+ NTP_REQUIRE(AF_INET == AF(addr) || AF_INET6 == AF(addr));
+
+ SET_HOSTMASK(&onesmask, AF(addr));
+ if (farewell) {
+ hack_restrict(RESTRICT_REMOVE, addr, &onesmask,
+ 0, 0, 0);
+ DPRINTF(1, ("restrict_source: %s removed", stoa(addr)));
+ return;
+ }
+
+ /*
+ * If there is a specific entry for this address, hands
+ * off, as it is condidered more specific than "restrict
+ * server ...".
+ * However, if the specific entry found is a fleeting one
+ * added by pool_xmit() before soliciting, replace it
+ * immediately regardless of the expire value to make way
+ * for the more persistent entry.
+ */
+ if (IS_IPV4(addr)) {
+ res = match_restrict4_addr(SRCADR(addr), SRCPORT(addr));
+ found_specific = (SRCADR(&onesmask) == res->u.v4.mask);
+ } else {
+ res = match_restrict6_addr(&SOCK_ADDR6(addr),
+ SRCPORT(addr));
+ found_specific = ADDR6_EQ(&res->u.v6.mask,
+ &SOCK_ADDR6(&onesmask));
+ }
+ if (!expire && found_specific && res->expire) {
+ found_specific = 0;
+ free_res(res, IS_IPV6(addr));
+ }
+ if (found_specific)
+ return;
+
+ hack_restrict(RESTRICT_FLAGS, addr, &onesmask,
+ restrict_source_mflags, restrict_source_flags,
+ expire);
+ DPRINTF(1, ("restrict_source: %s host restriction added\n",
+ stoa(addr)));
+}
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