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-rw-r--r--lib/zonecut.c593
1 files changed, 593 insertions, 0 deletions
diff --git a/lib/zonecut.c b/lib/zonecut.c
new file mode 100644
index 0000000..2bbd26f
--- /dev/null
+++ b/lib/zonecut.c
@@ -0,0 +1,593 @@
+/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "lib/zonecut.h"
+
+#include "contrib/cleanup.h"
+#include "lib/defines.h"
+#include "lib/generic/pack.h"
+#include "lib/resolve.h"
+#include "lib/rplan.h"
+
+#include <libknot/descriptor.h>
+#include <libknot/packet/wire.h>
+#include <libknot/rrtype/rdname.h>
+
+#define VERBOSE_MSG(qry, ...) kr_log_q(qry, ZCUT, __VA_ARGS__)
+
+/** Information for one NS name + address type. */
+typedef enum {
+ AI_UNINITED = 0,
+ AI_DISABLED, /**< Can't use this addrset. */
+ AI_CYCLED, /**< Skipped due to cycle detection; see implementation for details. */
+ AI_LAST_BAD = AI_CYCLED, /** bad states: <= AI_LAST_BAD */
+ AI_UNKNOWN, /**< Don't know status of this RRset; various reasons. */
+ AI_EMPTY, /**< No usable address (may mean e.g. just NODATA). */
+ AI_OK, /**< At least one usable address.
+ * LATER: we might be interested whether it's only glue. */
+} addrset_info_t;
+
+
+static void update_cut_name(struct kr_zonecut *cut, const knot_dname_t *name)
+{
+ if (knot_dname_is_equal(name, cut->name)) {
+ return;
+ }
+ knot_dname_t *next_name = knot_dname_copy(name, cut->pool);
+ mm_free(cut->pool, cut->name);
+ cut->name = next_name;
+}
+
+int kr_zonecut_init(struct kr_zonecut *cut, const knot_dname_t *name, knot_mm_t *pool)
+{
+ if (!cut || !name) {
+ return kr_error(EINVAL);
+ }
+
+ memset(cut, 0, sizeof(*cut));
+ cut->name = knot_dname_copy(name, pool);
+ cut->pool = pool;
+ cut->nsset = trie_create(pool);
+ return cut->name && cut->nsset ? kr_ok() : kr_error(ENOMEM);
+}
+
+/** Completely free a pack_t. */
+static inline void free_addr_set(pack_t *pack, knot_mm_t *pool)
+{
+ if (kr_fails_assert(pack)) {
+ /* promised we don't store NULL packs */
+ return;
+ }
+ pack_clear_mm(*pack, mm_free, pool);
+ mm_free(pool, pack);
+}
+/** Trivial wrapper for use in trie_apply, due to ugly casting. */
+static int free_addr_set_cb(trie_val_t *v, void *pool)
+{
+ free_addr_set(*v, pool);
+ return kr_ok();
+}
+
+void kr_zonecut_deinit(struct kr_zonecut *cut)
+{
+ if (!cut) {
+ return;
+ }
+ mm_free(cut->pool, cut->name);
+ if (cut->nsset) {
+ trie_apply(cut->nsset, free_addr_set_cb, cut->pool);
+ trie_free(cut->nsset);
+ }
+ knot_rrset_free(cut->key, cut->pool);
+ knot_rrset_free(cut->trust_anchor, cut->pool);
+}
+
+void kr_zonecut_move(struct kr_zonecut *to, const struct kr_zonecut *from)
+{
+ kr_require(to && from);
+ kr_zonecut_deinit(to);
+ memcpy(to, from, sizeof(*to));
+}
+
+void kr_zonecut_set(struct kr_zonecut *cut, const knot_dname_t *name)
+{
+ if (!cut || !name) {
+ return;
+ }
+ knot_rrset_t *key, *ta;
+ key = cut->key; cut->key = NULL;
+ ta = cut->trust_anchor; cut->trust_anchor = NULL;
+ kr_zonecut_deinit(cut);
+ kr_zonecut_init(cut, name, cut->pool);
+ cut->key = key;
+ cut->trust_anchor = ta;
+}
+
+int kr_zonecut_copy(struct kr_zonecut *dst, const struct kr_zonecut *src)
+{
+ if (!dst || !src) {
+ return kr_error(EINVAL);
+ }
+ if (!dst->nsset) {
+ dst->nsset = trie_create(dst->pool);
+ }
+ /* Copy the contents, one by one. */
+ int ret = kr_ok();
+ trie_it_t *it;
+ for (it = trie_it_begin(src->nsset); !trie_it_finished(it); trie_it_next(it)) {
+ size_t klen;
+ const char * const k = trie_it_key(it, &klen);
+ pack_t **new_pack = (pack_t **)trie_get_ins(dst->nsset, k, klen);
+ if (!new_pack) {
+ ret = kr_error(ENOMEM);
+ break;
+ }
+ const pack_t *old_pack = *trie_it_val(it);
+ ret = pack_clone(new_pack, old_pack, dst->pool);
+ if (ret) break;
+ }
+ trie_it_free(it);
+ return ret;
+}
+
+int kr_zonecut_copy_trust(struct kr_zonecut *dst, const struct kr_zonecut *src)
+{
+ knot_rrset_t *key_copy = NULL;
+ knot_rrset_t *ta_copy = NULL;
+
+ if (src->key) {
+ key_copy = knot_rrset_copy(src->key, dst->pool);
+ if (!key_copy) {
+ return kr_error(ENOMEM);
+ }
+ }
+
+ if (src->trust_anchor) {
+ ta_copy = knot_rrset_copy(src->trust_anchor, dst->pool);
+ if (!ta_copy) {
+ knot_rrset_free(key_copy, dst->pool);
+ return kr_error(ENOMEM);
+ }
+ }
+
+ knot_rrset_free(dst->key, dst->pool);
+ dst->key = key_copy;
+ knot_rrset_free(dst->trust_anchor, dst->pool);
+ dst->trust_anchor = ta_copy;
+
+ return kr_ok();
+}
+
+int kr_zonecut_add(struct kr_zonecut *cut, const knot_dname_t *ns, const void *data, int len)
+{
+ if (kr_fails_assert(cut && ns && cut->nsset && (!data || len > 0)))
+ return kr_error(EINVAL);
+ /* Disabled; add_reverse_pair() misuses this for domain name in rdata. */
+ if (false && data && len != sizeof(struct in_addr)
+ && len != sizeof(struct in6_addr)) {
+ kr_assert(!EINVAL);
+ return kr_error(EINVAL);
+ }
+
+ /* Get a pack_t for the ns. */
+ pack_t **pack = (pack_t **)trie_get_ins(cut->nsset, (const char *)ns, knot_dname_size(ns));
+ if (!pack) return kr_error(ENOMEM);
+ if (*pack == NULL) {
+ *pack = mm_alloc(cut->pool, sizeof(pack_t));
+ if (*pack == NULL) return kr_error(ENOMEM);
+ pack_init(**pack);
+ }
+ /* Insert data (if has any) */
+ if (data == NULL) {
+ return kr_ok();
+ }
+ /* Check for duplicates */
+ if (pack_obj_find(*pack, data, len)) {
+ return kr_ok();
+ }
+ /* Push new address */
+ int ret = pack_reserve_mm(**pack, 1, len, kr_memreserve, cut->pool);
+ if (ret != 0) {
+ return kr_error(ENOMEM);
+ }
+ return pack_obj_push(*pack, data, len);
+}
+
+int kr_zonecut_del(struct kr_zonecut *cut, const knot_dname_t *ns, const void *data, int len)
+{
+ if (!cut || !ns || (data && len <= 0)) {
+ return kr_error(EINVAL);
+ }
+
+ /* Find the address list. */
+ int ret = kr_ok();
+ pack_t *pack = kr_zonecut_find(cut, ns);
+ if (pack == NULL) {
+ return kr_error(ENOENT);
+ }
+ /* Remove address from the pack. */
+ if (data) {
+ ret = pack_obj_del(pack, data, len);
+ }
+ /* No servers left, remove NS from the set. */
+ if (pack->len == 0) {
+ free_addr_set(pack, cut->pool);
+ ret = trie_del(cut->nsset, (const char *)ns, knot_dname_size(ns), NULL);
+ if (kr_fails_assert(ret == 0)) /* only KNOT_ENOENT and that *can't* happen */
+ return kr_error(ret);
+ return kr_ok();
+ }
+
+ return ret;
+}
+
+int kr_zonecut_del_all(struct kr_zonecut *cut, const knot_dname_t *ns)
+{
+ if (!cut || !ns) {
+ return kr_error(EINVAL);
+ }
+
+ /* Find the address list; then free and remove it. */
+ pack_t *pack;
+ int ret = trie_del(cut->nsset, (const char *)ns, knot_dname_size(ns),
+ (trie_val_t *)&pack);
+ if (ret) { /* deletion failed */
+ kr_assert(ret == KNOT_ENOENT);
+ return kr_error(ENOENT);
+ }
+ free_addr_set(pack, cut->pool);
+ return kr_ok();
+}
+
+pack_t *kr_zonecut_find(struct kr_zonecut *cut, const knot_dname_t *ns)
+{
+ if (!cut || !ns) {
+ return NULL;
+ }
+ trie_val_t *val = trie_get_try(cut->nsset, (const char *)ns, knot_dname_size(ns));
+ /* we get pointer to the pack_t pointer */
+ return val ? (pack_t *)*val : NULL;
+}
+
+static int has_address(trie_val_t *v, void *baton_)
+{
+ const pack_t *pack = *v;
+ const bool found = pack != NULL && pack->len != 0;
+ return found;
+}
+
+bool kr_zonecut_is_empty(struct kr_zonecut *cut)
+{
+ if (kr_fails_assert(cut && cut->nsset))
+ return true;
+ return !trie_apply(cut->nsset, has_address, NULL);
+}
+
+int kr_zonecut_set_sbelt(struct kr_context *ctx, struct kr_zonecut *cut)
+{
+ if (!ctx || !cut || !ctx->root_hints.nsset) {
+ return kr_error(EINVAL);
+ }
+
+ trie_apply(cut->nsset, free_addr_set_cb, cut->pool);
+ trie_clear(cut->nsset);
+
+ const uint8_t *const dname_root = (const uint8_t *)/*sign-cast*/("");
+ update_cut_name(cut, dname_root);
+ /* Copy root hints from resolution context. */
+ return kr_zonecut_copy(cut, &ctx->root_hints);
+}
+
+/** Fetch address for zone cut. Any rank is accepted (i.e. glue as well). */
+static addrset_info_t fetch_addr(pack_t *addrs, const knot_dname_t *ns, uint16_t rrtype,
+ int *addr_budget,
+ knot_mm_t *mm_pool, const struct kr_query *qry)
+// LATER(optim.): excessive data copying
+{
+ int rdlen;
+ switch (rrtype) {
+ case KNOT_RRTYPE_A:
+ if (qry->flags.NO_IPV4)
+ return AI_DISABLED;
+ rdlen = 4;
+ break;
+ case KNOT_RRTYPE_AAAA:
+ if (qry->flags.NO_IPV6 || no6_is_bad())
+ return AI_DISABLED;
+ rdlen = 16;
+ break;
+ default:
+ kr_assert(!EINVAL);
+ return AI_UNKNOWN;
+ }
+
+ struct kr_context *ctx = qry->request->ctx;
+ struct kr_cache_p peek;
+ if (kr_cache_peek_exact(&ctx->cache, ns, rrtype, &peek) != 0) {
+ return AI_UNKNOWN;
+ }
+ int32_t new_ttl = kr_cache_ttl(&peek, qry, ns, rrtype);
+ if (new_ttl < 0) {
+ return AI_UNKNOWN;
+ }
+
+ knot_rrset_t cached_rr;
+ knot_rrset_init(&cached_rr, /*const-cast*/(knot_dname_t *)ns, rrtype,
+ KNOT_CLASS_IN, new_ttl);
+ if (kr_cache_materialize(&cached_rr.rrs, &peek, mm_pool) < 0) {
+ return AI_UNKNOWN;
+ }
+
+ *addr_budget -= cached_rr.rrs.count - 1;
+ if (*addr_budget < 0) {
+ cached_rr.rrs.count += *addr_budget;
+ *addr_budget = 0;
+ }
+
+ /* Reserve memory in *addrs. Implementation detail:
+ * pack_t cares for lengths, so we don't store those in the data. */
+ const size_t pack_extra_size = cached_rr.rrs.size
+ - cached_rr.rrs.count * offsetof(knot_rdata_t, len);
+ int ret = pack_reserve_mm(*addrs, cached_rr.rrs.count, pack_extra_size,
+ kr_memreserve, mm_pool);
+ kr_require(ret == 0); /* ENOMEM "probably" */
+
+ int usable_cnt = 0;
+ addrset_info_t result = AI_EMPTY;
+ knot_rdata_t *rd = cached_rr.rrs.rdata;
+ for (uint16_t i = 0; i < cached_rr.rrs.count; ++i, rd = knot_rdataset_next(rd)) {
+ if (unlikely(rd->len != rdlen)) {
+ VERBOSE_MSG(qry, "bad NS address length %d for rrtype %d, skipping\n",
+ (int)rd->len, (int)rrtype);
+ continue;
+ }
+ result = AI_OK;
+ ++usable_cnt;
+
+ ret = pack_obj_push(addrs, rd->data, rd->len);
+ kr_assert(!ret); /* didn't fit because of incorrectly reserved memory */
+ /* LATER: for now we lose quite some information here,
+ * as keeping it would need substantial changes on other places,
+ * and it turned out to be premature optimization (most likely).
+ * We might e.g. skip adding unusable addresses,
+ * and either keep some rtt information associated
+ * or even finish up choosing the set to send packets to.
+ * Overall there's some overlap with nsrep.c functionality.
+ */
+ }
+ if (usable_cnt != cached_rr.rrs.count) {
+ VERBOSE_MSG(qry, "usable NS addresses: %d/%d\n",
+ usable_cnt, cached_rr.rrs.count);
+ }
+ return result;
+}
+
+/** Fetch best NS for zone cut. */
+static int fetch_ns(struct kr_context *ctx, struct kr_zonecut *cut,
+ const knot_dname_t *name, const struct kr_query *qry,
+ uint8_t * restrict rank)
+{
+ struct kr_cache_p peek;
+ int ret = kr_cache_peek_exact(&ctx->cache, name, KNOT_RRTYPE_NS, &peek);
+ if (ret != 0) {
+ return ret;
+ }
+ /* Note: we accept *any* rank from the cache. We assume that nothing
+ * completely untrustworthy could get into the cache, e.g out-of-bailiwick
+ * records that weren't validated.
+ */
+ *rank = peek.rank;
+
+ int32_t new_ttl = kr_cache_ttl(&peek, qry, name, KNOT_RRTYPE_NS);
+ if (new_ttl < 0) {
+ return kr_error(ESTALE);
+ }
+ /* Materialize the rdataset temporarily, for simplicity. */
+ knot_rdataset_t ns_rds = { 0 };
+ ret = kr_cache_materialize(&ns_rds, &peek, cut->pool);
+ if (ret < 0) {
+ return ret;
+ }
+
+ /* Consider at most 13 first NSs (like root). It's a trivial approach
+ * to limit our resources when choosing NSs. Otherwise DoS might be viable.
+ * We're not aware of any reasonable use case for having many NSs. */
+ if (ns_rds.count > 13) {
+ if (kr_log_is_debug_qry(ZCUT, qry)) {
+ auto_free char *name_txt = kr_dname_text(name);
+ VERBOSE_MSG(qry, "NS %s too large, reducing from %d names\n",
+ name_txt, (int)ns_rds.count);
+ }
+ ns_rds.count = 13;
+ }
+ /* Also trivially limit the total address count:
+ * first A and first AAAA are for free per NS,
+ * but the rest get a shared small limit and get skipped if exhausted. */
+ int addr_budget = 8;
+
+ /* Insert name servers for this zone cut, addresses will be looked up
+ * on-demand (either from cache or iteratively) */
+ bool all_bad = true; /**< All NSs (seen so far) are in a bad state. */
+ knot_rdata_t *rdata_i = ns_rds.rdata;
+ for (unsigned i = 0; i < ns_rds.count;
+ ++i, rdata_i = knot_rdataset_next(rdata_i)) {
+ const knot_dname_t *ns_name = knot_ns_name(rdata_i);
+ const size_t ns_size = knot_dname_size(ns_name);
+
+ /* Get a new pack within the nsset. */
+ pack_t **pack = (pack_t **)trie_get_ins(cut->nsset,
+ (const char *)ns_name, ns_size);
+ if (!pack) return kr_error(ENOMEM);
+ kr_assert(!*pack); /* not critical, really */
+ *pack = mm_alloc(cut->pool, sizeof(pack_t));
+ if (!*pack) return kr_error(ENOMEM);
+ pack_init(**pack);
+
+ addrset_info_t infos[2];
+
+ /* Fetch NS reputation and decide whether to prefetch A/AAAA records. */
+ infos[0] = fetch_addr(*pack, ns_name, KNOT_RRTYPE_A, &addr_budget,
+ cut->pool, qry);
+ infos[1] = fetch_addr(*pack, ns_name, KNOT_RRTYPE_AAAA, &addr_budget,
+ cut->pool, qry);
+
+ #if 0 /* rather unlikely to be useful unless changing some zcut code */
+ if (kr_log_is_debug_qry(ZCUT, qry)) {
+ auto_free char *ns_name_txt = kr_dname_text(ns_name);
+ VERBOSE_MSG(qry, "NS %s infos: %d, %d\n",
+ ns_name_txt, (int)infos[0], (int)infos[1]);
+ }
+ #endif
+
+ /* AI_CYCLED checks.
+ * If an ancestor query has its zone cut in the state that
+ * it's looking for name or address(es) of some NS(s),
+ * we want to avoid doing so with a NS that lies under its cut.
+ * Instead we need to consider such names unusable in the cut (for now). */
+ if (infos[0] != AI_UNKNOWN && infos[1] != AI_UNKNOWN) {
+ /* Optimization: the following loop would be pointless. */
+ all_bad = false;
+ continue;
+ }
+ for (const struct kr_query *aq = qry; aq->parent; aq = aq->parent) {
+ const struct kr_qflags *aqpf = &aq->parent->flags;
+ if ( (aqpf->AWAIT_CUT && aq->stype == KNOT_RRTYPE_NS)
+ || (aqpf->AWAIT_IPV4 && aq->stype == KNOT_RRTYPE_A)
+ || (aqpf->AWAIT_IPV6 && aq->stype == KNOT_RRTYPE_AAAA)) {
+ if (knot_dname_in_bailiwick(ns_name,
+ aq->parent->zone_cut.name)) {
+ for (int j = 0; j < 2; ++j)
+ if (infos[j] == AI_UNKNOWN)
+ infos[j] = AI_CYCLED;
+ break;
+ }
+ } else {
+ /* This ancestor waits for other reason that
+ * NS name or address, so we're out of a direct cycle. */
+ break;
+ }
+ }
+ all_bad = all_bad && infos[0] <= AI_LAST_BAD && infos[1] <= AI_LAST_BAD;
+ }
+
+ if (all_bad && kr_log_is_debug_qry(ZCUT, qry)) {
+ auto_free char *name_txt = kr_dname_text(name);
+ VERBOSE_MSG(qry, "cut %s: all NSs bad, count = %d\n",
+ name_txt, (int)ns_rds.count);
+ }
+
+ kr_assert(addr_budget >= 0);
+ if (addr_budget <= 0 && kr_log_is_debug_qry(ZCUT, qry)) {
+ auto_free char *name_txt = kr_dname_text(name);
+ VERBOSE_MSG(qry, "NS %s have too many addresses together, reduced\n",
+ name_txt);
+ }
+
+ knot_rdataset_clear(&ns_rds, cut->pool);
+ return all_bad ? ELOOP : kr_ok();
+}
+
+/**
+ * Fetch secure RRSet of given type.
+ */
+static int fetch_secure_rrset(knot_rrset_t **rr, struct kr_cache *cache,
+ const knot_dname_t *owner, uint16_t type, knot_mm_t *pool,
+ const struct kr_query *qry)
+{
+ if (kr_fails_assert(rr))
+ return kr_error(EINVAL);
+ /* peek, check rank and TTL */
+ struct kr_cache_p peek;
+ int ret = kr_cache_peek_exact(cache, owner, type, &peek);
+ if (ret != 0)
+ return ret;
+ if (!kr_rank_test(peek.rank, KR_RANK_SECURE))
+ return kr_error(ENOENT);
+ int32_t new_ttl = kr_cache_ttl(&peek, qry, owner, type);
+ if (new_ttl < 0)
+ return kr_error(ESTALE);
+ /* materialize a new RRset */
+ knot_rrset_free(*rr, pool);
+ *rr = mm_alloc(pool, sizeof(knot_rrset_t));
+ if (*rr == NULL)
+ return kr_error(ENOMEM);
+ owner = knot_dname_copy(/*const-cast*/(knot_dname_t *)owner, pool);
+ if (!owner) {
+ mm_free(pool, *rr);
+ *rr = NULL;
+ return kr_error(ENOMEM);
+ }
+ knot_rrset_init(*rr, /*const-cast*/(knot_dname_t *)owner, type,
+ KNOT_CLASS_IN, new_ttl);
+ ret = kr_cache_materialize(&(*rr)->rrs, &peek, pool);
+ if (ret < 0) {
+ knot_rrset_free(*rr, pool);
+ *rr = NULL;
+ return ret;
+ }
+
+ return kr_ok();
+}
+
+int kr_zonecut_find_cached(struct kr_context *ctx, struct kr_zonecut *cut,
+ const knot_dname_t *name, const struct kr_query *qry,
+ bool * restrict secured)
+{
+ if (!ctx || !cut || !name)
+ return kr_error(EINVAL);
+ /* I'm not sure whether the caller always passes a clean state;
+ * mixing doesn't seem to make sense in any case, so let's clear it.
+ * We don't bother freeing the packs, as they're on mempool. */
+ trie_clear(cut->nsset);
+ /* Copy name as it may overlap with cut name that is to be replaced. */
+ knot_dname_t *qname = knot_dname_copy(name, cut->pool);
+ if (!qname) {
+ return kr_error(ENOMEM);
+ }
+ /* Start at QNAME. */
+ int ret;
+ const knot_dname_t *label = qname;
+ while (true) {
+ /* Fetch NS first and see if it's insecure. */
+ uint8_t rank = 0;
+ const bool is_root = (label[0] == '\0');
+ ret = fetch_ns(ctx, cut, label, qry, &rank);
+ if (ret == 0) {
+ /* Flag as insecure if cached as this */
+ if (kr_rank_test(rank, KR_RANK_INSECURE)) {
+ *secured = false;
+ }
+ /* Fetch DS and DNSKEY if caller wants secure zone cut */
+ int ret_ds = 1, ret_dnskey = 1;
+ if (*secured || is_root) {
+ ret_ds = fetch_secure_rrset(&cut->trust_anchor, &ctx->cache,
+ label, KNOT_RRTYPE_DS, cut->pool, qry);
+ ret_dnskey = fetch_secure_rrset(&cut->key, &ctx->cache,
+ label, KNOT_RRTYPE_DNSKEY, cut->pool, qry);
+ }
+ update_cut_name(cut, label);
+ if (kr_log_is_debug_qry(ZCUT, qry)) {
+ auto_free char *label_str = kr_dname_text(label);
+ VERBOSE_MSG(qry,
+ "found cut: %s (rank 0%.2o return codes: DS %d, DNSKEY %d)\n",
+ label_str, rank, ret_ds, ret_dnskey);
+ }
+ ret = kr_ok();
+ break;
+ } /* else */
+
+ trie_clear(cut->nsset);
+ /* Subtract label from QNAME. */
+ if (!is_root) {
+ label = knot_wire_next_label(label, NULL);
+ } else {
+ ret = kr_error(ENOENT);
+ break;
+ }
+ }
+
+ kr_cache_commit(&ctx->cache);
+ mm_free(cut->pool, qname);
+ return ret;
+}
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