Adding upstream version 5.6.0.upstream/5.6.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 488 insertions, 0 deletions

diff --git a/lib/cache/nsec1.c b/lib/cache/nsec1.c
new file mode 100644
index 0000000..4554303
--- /dev/null
+++ b/lib/cache/nsec1.c
@@ -0,0 +1,488 @@
+/*  Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/** @file
+ * Implementation of NSEC (1) handling.  Prototypes in ./impl.h
+ */
+
+#include "lib/cache/impl.h"
+#include "lib/dnssec/nsec.h"
+#include "lib/layer/iterate.h"
+
+
+/** Reconstruct a name into a buffer (assuming length at least KNOT_DNAME_MAXLEN).
+ * \return kr_ok() or error code (<0). */
+static int dname_wire_reconstruct(knot_dname_t *buf, const struct key *k,
+		 knot_db_val_t kwz)
+{
+	/* Reconstruct from key: first the ending, then zone name. */
+	int ret = knot_dname_lf2wire(buf, kwz.len, kwz.data);
+	if (kr_fails_assert(ret >= 0)) {
+		VERBOSE_MSG(NULL, "=> NSEC: LF2wire ret = %d\n", ret);
+		return ret;
+	}
+		/* The last written byte is the zero label for root -> overwrite. */
+	knot_dname_t *zone_start = buf + ret - 1;
+	if (kr_fails_assert(*zone_start == '\0'))
+		return kr_error(EFAULT);
+	ret = knot_dname_to_wire(zone_start, k->zname, KNOT_DNAME_MAXLEN - kwz.len);
+	if (kr_fails_assert(ret == k->zlf_len + 1))
+		return ret < 0 ? ret : kr_error(EILSEQ);
+	return kr_ok();
+}
+
+
+knot_db_val_t key_NSEC1(struct key *k, const knot_dname_t *name, bool add_wildcard)
+{
+	/* we basically need dname_lf with two bytes added
+	 * on a correct place within the name (the cut) */
+	int ret;
+	const bool ok = k && name
+		&& !(ret = kr_dname_lf(k->buf, name, add_wildcard));
+	if (kr_fails_assert(ok))
+		return (knot_db_val_t){ NULL, 0 };
+
+	uint8_t *begin = k->buf + 1 + k->zlf_len; /* one byte after zone's zero */
+	uint8_t *end = k->buf + 1 + k->buf[0]; /* we don't use the final zero in key,
+						* but move it anyway */
+	if (kr_fails_assert(end >= begin))
+		return (knot_db_val_t){ NULL, 0 };
+	int key_len;
+	if (end > begin) {
+		memmove(begin + 2, begin, end - begin);
+		key_len = k->buf[0] + 1;
+	} else {
+		key_len = k->buf[0] + 2;
+	}
+	/* CACHE_KEY_DEF: key == zone's dname_lf + '\0' + '1' + dname_lf
+	 * of the name within the zone without the final 0.  Iff the latter is empty,
+	 * there's no zero to cut and thus the key_len difference.
+	 */
+	begin[0] = 0;
+	begin[1] = '1'; /* tag for NSEC1 */
+	k->type = KNOT_RRTYPE_NSEC;
+
+	/*
+	VERBOSE_MSG(NULL, "<> key_NSEC1; name: ");
+	kr_dname_print(name, add_wildcard ? "*." : "" , " ");
+	kr_log_debug(CACHE, "(zone name LF length: %d; total key length: %d)\n",
+			k->zlf_len, key_len);
+	*/
+
+	return (knot_db_val_t){ k->buf + 1, key_len };
+}
+
+
+/** Assuming that k1 < k4, find where k2 is.  (Considers DNS wrap-around.)
+ *
+ * \return Intuition: position of k2 among kX.
+ *	0: k2 < k1;  1: k1 == k2;  2: k1 is a prefix of k2 < k4;
+ *	3: k1 < k2 < k4 (and not 2);  4: k2 == k4;  5: k2 > k4
+ * \note k1.data may be NULL, meaning assumption that k1 < k2 and not a prefix
+ *       (i.e. return code will be > 2)
+ */
+static int kwz_between(knot_db_val_t k1, knot_db_val_t k2, knot_db_val_t k4)
+{
+	kr_require(k2.data && k4.data);
+	/* CACHE_KEY_DEF; we need to beware of one key being a prefix of another */
+	int ret_maybe; /**< result, assuming we confirm k2 < k4 */
+	if (k1.data) {
+		const int cmp12 = memcmp(k1.data, k2.data, MIN(k1.len, k2.len));
+		if (cmp12 == 0 && k1.len == k2.len) /* iff k1 == k2 */
+			return 1;
+		if (cmp12 > 0 || (cmp12 == 0 && k1.len > k2.len)) /* iff k1 > k2 */
+			return 0;
+		ret_maybe = cmp12 == 0 ? 2 : 3;
+	} else {
+		ret_maybe = 3;
+	}
+	if (k4.len == 0) { /* wrap-around */
+		return k2.len > 0 ? ret_maybe : 4;
+	} else {
+		const int cmp24 = memcmp(k2.data, k4.data, MIN(k2.len, k4.len));
+		if (cmp24 == 0 && k2.len == k4.len) /* iff k2 == k4 */
+			return 4;
+		if (cmp24 > 0 || (cmp24 == 0 && k2.len > k4.len)) /* iff k2 > k4 */
+			return 5;
+		return ret_maybe;
+	}
+}
+
+
+/** NSEC1 range search.
+ *
+ * \param key Pass output of key_NSEC1(k, ...)
+ * \param value[out] The raw data of the NSEC cache record (optional; consistency checked).
+ * \param exact_match[out] Whether the key was matched exactly or just covered (optional).
+ * \param kwz_low[out] Output the low end of covering NSEC, pointing within DB (optional).
+ * \param kwz_high[in,out] Storage for the high end of covering NSEC (optional).
+ * 		It's only set if !exact_match.
+ * \param new_ttl[out] New TTL of the NSEC (optional).
+ * \return Error message or NULL.
+ * \note The function itself does *no* bitmap checks, e.g. RFC 6840 sec. 4.
+ */
+static const char * find_leq_NSEC1(struct kr_cache *cache, const struct kr_query *qry,
+			const knot_db_val_t key, const struct key *k, knot_db_val_t *value,
+			bool *exact_match, knot_db_val_t *kwz_low, knot_db_val_t *kwz_high,
+			uint32_t *new_ttl)
+{
+	/* Do the cache operation. */
+	const size_t nwz_off = key_nwz_off(k);
+	if (kr_fails_assert(key.data && key.len >= nwz_off))
+		return "range search ERROR";
+	knot_db_val_t key_nsec = key;
+	knot_db_val_t val = { NULL, 0 };
+	int ret = cache_op(cache, read_leq, &key_nsec, &val);
+	if (ret < 0) {
+		if (kr_fails_assert(ret == kr_error(ENOENT))) {
+			return "range search ERROR";
+		} else {
+			return "range search miss";
+		}
+	}
+	if (value) {
+		*value = val;
+	}
+	/* Check consistency, TTL, rank. */
+	const bool is_exact = (ret == 0);
+	if (exact_match) {
+		*exact_match = is_exact;
+	}
+	const struct entry_h *eh = entry_h_consistent_NSEC(val);
+	if (!eh) {
+		/* This might be just finding something else than NSEC1 entry,
+		 * in case we searched before the very first one in the zone. */
+		return "range search found inconsistent entry";
+	}
+	/* Passing just zone name instead of owner, as we don't
+	 * have it reconstructed at this point. */
+	int32_t new_ttl_ = get_new_ttl(eh, qry, k->zname, KNOT_RRTYPE_NSEC,
+					qry->timestamp.tv_sec);
+	if (new_ttl_ < 0 || !kr_rank_test(eh->rank, KR_RANK_SECURE)) {
+		return "range search found stale or insecure entry";
+		/* TODO: remove the stale record *and* retry,
+		 * in case we haven't run off.  Perhaps start by in_zone check. */
+	}
+	if (new_ttl) {
+		*new_ttl = new_ttl_;
+	}
+	if (kwz_low) {
+		*kwz_low = (knot_db_val_t){
+			.data = (uint8_t *)key_nsec.data + nwz_off,
+			.len = key_nsec.len - nwz_off,
+		};	/* CACHE_KEY_DEF */
+	}
+	if (is_exact) {
+		/* Nothing else to do. */
+		return NULL;
+	}
+	/* The NSEC starts strictly before our target name;
+	 * now check that it still belongs into that zone. */
+	const bool nsec_in_zone = key_nsec.len >= nwz_off
+		/* CACHE_KEY_DEF */
+		&& memcmp(key.data, key_nsec.data, nwz_off) == 0;
+	if (!nsec_in_zone) {
+		return "range search miss (!nsec_in_zone)";
+	}
+	/* We know it starts before sname, so let's check the other end.
+	 * 1. construct the key for the next name - kwz_hi. */
+	/* it's *full* name ATM */
+	/* Technical complication: memcpy is safe for unaligned case (on non-x86) */
+	__typeof__(((knot_rdata_t *)NULL)->len) next_len;
+	const uint8_t *next_data;
+	{	/* next points to knot_rdata_t but possibly unaligned */
+		const uint8_t *next = eh->data + KR_CACHE_RR_COUNT_SIZE;
+		memcpy(&next_len, next + offsetof(knot_rdata_t, len), sizeof(next_len));
+		next_data = next + offsetof(knot_rdata_t, data);
+	}
+	if (kr_fails_assert(KR_CACHE_RR_COUNT_SIZE == 2 && get_uint16(eh->data) != 0)) {
+		return "ERROR"; /* TODO: more checks? */
+	}
+	/*
+	WITH_VERBOSE {
+		VERBOSE_MSG(qry, "=> NSEC: next name: ");
+		kr_dname_print(next, "", "\n");
+	}
+	*/
+	knot_dname_t ch_buf[KNOT_DNAME_MAXLEN];
+	knot_dname_t *chs = kwz_high ? kwz_high->data : ch_buf;
+	if (kr_fails_assert(chs))
+		return "EINVAL";
+
+	{
+		/* Lower-case chs; see also RFC 6840 5.1.
+		 * LATER(optim.): we do lots of copying etc. */
+		knot_dname_t lower_buf[KNOT_DNAME_MAXLEN];
+		ret = knot_dname_to_wire(lower_buf, next_data,
+					 MIN(next_len, KNOT_DNAME_MAXLEN));
+		if (ret < 0) { /* _ESPACE */
+			return "range search found record with incorrect contents";
+		}
+		knot_dname_to_lower(lower_buf);
+		ret = kr_dname_lf(chs, lower_buf, false);
+	}
+
+	if (kr_fails_assert(ret == 0))
+		return "ERROR";
+	knot_db_val_t kwz_hi = { /* skip the zone name */
+		.data = chs + 1 + k->zlf_len,
+		.len = chs[0] - k->zlf_len,
+	};
+	if (kr_fails_assert((ssize_t)(kwz_hi.len) >= 0))
+		return "ERROR";
+	/* 2. do the actual range check. */
+	const knot_db_val_t kwz_sname = {
+		.data = (void *)/*const-cast*/(k->buf + 1 + nwz_off),
+		.len = k->buf[0] - k->zlf_len,
+	};
+	if (kr_fails_assert((ssize_t)(kwz_sname.len) >= 0))
+		return "ERROR";
+	bool covers = /* we know for sure that the low end is before kwz_sname */
+		3 == kwz_between((knot_db_val_t){ NULL, 0 }, kwz_sname, kwz_hi);
+	if (!covers) {
+		return "range search miss (!covers)";
+	}
+	if (kwz_high) {
+		*kwz_high = kwz_hi;
+	}
+	return NULL;
+}
+
+
+int nsec1_encloser(struct key *k, struct answer *ans,
+		   const int sname_labels, int *clencl_labels,
+		   knot_db_val_t *cover_low_kwz, knot_db_val_t *cover_hi_kwz,
+		   const struct kr_query *qry, struct kr_cache *cache)
+{
+	static const int ESKIP = ABS(ENOENT);
+	/* Basic sanity check. */
+	const bool ok = k && ans && clencl_labels && cover_low_kwz && cover_hi_kwz
+			&& qry && cache;
+	if (kr_fails_assert(ok))
+		return kr_error(EINVAL);
+
+	/* Find a previous-or-equal name+NSEC in cache covering the QNAME,
+	 * checking TTL etc. */
+	knot_db_val_t key = key_NSEC1(k, qry->sname, false);
+	knot_db_val_t val = { NULL, 0 };
+	bool exact_match;
+	uint32_t new_ttl;
+	const char *err = find_leq_NSEC1(cache, qry, key, k, &val,
+			&exact_match, cover_low_kwz, cover_hi_kwz, &new_ttl);
+	if (err) {
+		VERBOSE_MSG(qry, "=> NSEC sname: %s\n", err);
+		return ESKIP;
+	}
+
+	/* Get owner name of the record. */
+	const knot_dname_t *owner;
+	knot_dname_t owner_buf[KNOT_DNAME_MAXLEN];
+	if (exact_match) {
+		owner = qry->sname;
+	} else {
+		int ret = dname_wire_reconstruct(owner_buf, k, *cover_low_kwz);
+		if (unlikely(ret)) return ESKIP;
+		owner = owner_buf;
+	}
+	/* Basic checks OK -> materialize data. */
+	{
+		const struct entry_h *nsec_eh = val.data;
+		int ret = entry2answer(ans, AR_NSEC, nsec_eh, knot_db_val_bound(val),
+					owner, KNOT_RRTYPE_NSEC, new_ttl);
+		if (ret) return kr_error(ret);
+	}
+
+	/* Final checks, split for matching vs. covering our sname. */
+	const knot_rrset_t *nsec_rr = ans->rrsets[AR_NSEC].set.rr;
+	const uint8_t *bm = knot_nsec_bitmap(nsec_rr->rrs.rdata);
+	uint16_t bm_size = knot_nsec_bitmap_len(nsec_rr->rrs.rdata);
+	if (kr_fails_assert(bm))
+		return kr_error(EFAULT);
+
+	if (exact_match) {
+		if (kr_nsec_bitmap_nodata_check(bm, bm_size, qry->stype, nsec_rr->owner) != 0) {
+			VERBOSE_MSG(qry,
+				"=> NSEC sname: match but failed type check\n");
+			return ESKIP;
+		}
+		/* NODATA proven; just need to add SOA+RRSIG later */
+		VERBOSE_MSG(qry, "=> NSEC sname: match proved NODATA, new TTL %d\n",
+				new_ttl);
+		ans->rcode = PKT_NODATA;
+		return kr_ok();
+	} /* else */
+
+	/* Inexact match.  First check if sname is delegated by that NSEC. */
+	const int nsec_matched = knot_dname_matched_labels(nsec_rr->owner, qry->sname);
+	const bool is_sub = nsec_matched == knot_dname_labels(nsec_rr->owner, NULL);
+	if (is_sub && kr_nsec_children_in_zone_check(bm, bm_size) != 0) {
+		VERBOSE_MSG(qry, "=> NSEC sname: covered but delegated (or error)\n");
+		return ESKIP;
+	}
+	/* NXDOMAIN proven *except* for wildcards. */
+	WITH_VERBOSE(qry) {
+		auto_free char *owner_str = kr_dname_text(nsec_rr->owner),
+			  *next_str = kr_dname_text(knot_nsec_next(nsec_rr->rrs.rdata));
+		VERBOSE_MSG(qry, "=> NSEC sname: covered by: %s -> %s, new TTL %d\n",
+				owner_str, next_str, new_ttl);
+	}
+
+	/* Find label count of the closest encloser.
+	 * Both endpoints in an NSEC do exist (though possibly in a child zone)
+	 * and any prefixes of those names as well (empty non-terminals),
+	 * but nothing else exists inside this "triangle".
+	 *
+	 * Note that we have to lower-case the next name for comparison,
+	 * even though we have canonicalized NSEC already; see RFC 6840 5.1.
+	 * LATER(optim.): it might be faster to use the LFs we already have.
+	 */
+	knot_dname_t next[KNOT_DNAME_MAXLEN];
+	int ret = knot_dname_to_wire(next, knot_nsec_next(nsec_rr->rrs.rdata), sizeof(next));
+	if (kr_fails_assert(ret >= 0))
+		return kr_error(ret);
+	knot_dname_to_lower(next);
+	*clencl_labels = MAX(
+		nsec_matched,
+		knot_dname_matched_labels(qry->sname, next)
+		);
+
+	/* Empty non-terminals don't need to have
+	 * a matching NSEC record. */
+	if (sname_labels == *clencl_labels) {
+		ans->rcode = PKT_NODATA;
+		VERBOSE_MSG(qry,
+			"=> NSEC sname: empty non-terminal by the same RR\n");
+	} else {
+		ans->rcode = PKT_NXDOMAIN;
+	}
+	return kr_ok();
+}
+
+/** Verify non-existence after kwz_between() call. */
+static bool nonexistence_ok(int cmp, const knot_rrset_t *rrs)
+{
+	if (cmp == 3) {
+		return true;
+	}
+	if (cmp != 2) {
+		return false;
+	}
+	const uint8_t *bm = knot_nsec_bitmap(rrs->rrs.rdata);
+	uint16_t bm_size = knot_nsec_bitmap_len(rrs->rrs.rdata);
+	return kr_nsec_children_in_zone_check(bm, bm_size) != 0;
+}
+
+int nsec1_src_synth(struct key *k, struct answer *ans, const knot_dname_t *clencl_name,
+		    knot_db_val_t cover_low_kwz, knot_db_val_t cover_hi_kwz,
+		    const struct kr_query *qry, struct kr_cache *cache)
+{
+	/* Construct key for the source of synthesis. */
+	knot_db_val_t key = key_NSEC1(k, clencl_name, true);
+	const size_t nwz_off = key_nwz_off(k);
+	if (kr_fails_assert(key.data && key.len >= nwz_off))
+		return kr_error(1);
+	/* Check if our sname-covering NSEC also covers/matches SS. */
+	knot_db_val_t kwz = {
+		.data = (uint8_t *)key.data + nwz_off,
+		.len = key.len - nwz_off,
+	};
+	if (kr_fails_assert((ssize_t)(kwz.len) >= 0))
+		return kr_error(EINVAL);
+	const int cmp = kwz_between(cover_low_kwz, kwz, cover_hi_kwz);
+	if (nonexistence_ok(cmp, ans->rrsets[AR_NSEC].set.rr)) {
+		VERBOSE_MSG(qry, "=> NSEC wildcard: covered by the same RR\n");
+		return AR_SOA;
+	}
+	const knot_rrset_t *nsec_rr = NULL; /**< the wildcard proof NSEC */
+	bool exact_match; /**< whether it matches the source of synthesis */
+	if (cmp == 1) {
+		exact_match = true;
+		nsec_rr = ans->rrsets[AR_NSEC].set.rr;
+	} else {
+		/* Try to find the NSEC for SS. */
+		knot_db_val_t val = { NULL, 0 };
+		knot_db_val_t wild_low_kwz = { NULL, 0 };
+		uint32_t new_ttl;
+		const char *err = find_leq_NSEC1(cache, qry, key, k, &val,
+				&exact_match, &wild_low_kwz, NULL, &new_ttl);
+		if (err) {
+			VERBOSE_MSG(qry, "=> NSEC wildcard: %s\n", err);
+			return kr_ok();
+		}
+		/* Materialize the record into answer (speculatively). */
+		knot_dname_t owner[KNOT_DNAME_MAXLEN];
+		int ret = dname_wire_reconstruct(owner, k, wild_low_kwz);
+		if (ret) return kr_error(ret);
+		const struct entry_h *nsec_eh = val.data;
+		ret = entry2answer(ans, AR_WILD, nsec_eh, knot_db_val_bound(val),
+				   owner, KNOT_RRTYPE_NSEC, new_ttl);
+		if (ret) return kr_error(ret);
+		nsec_rr = ans->rrsets[AR_WILD].set.rr;
+	}
+
+	if (kr_fails_assert(nsec_rr))
+		return kr_error(EFAULT);
+	const uint8_t *bm = knot_nsec_bitmap(nsec_rr->rrs.rdata);
+	uint16_t bm_size = knot_nsec_bitmap_len(nsec_rr->rrs.rdata);
+	int ret;
+	struct answer_rrset * const arw = &ans->rrsets[AR_WILD];
+	if (kr_fails_assert(bm)) {
+		ret = kr_error(EFAULT);
+		goto clean_wild;
+	}
+	if (!exact_match) {
+		/* Finish verification that the source of synthesis doesn't exist. */
+		const int nsec_matched =
+			knot_dname_matched_labels(nsec_rr->owner, clencl_name);
+			/* we don't need to use the full source of synthesis ^ */
+		const bool is_sub =
+			nsec_matched == knot_dname_labels(nsec_rr->owner, NULL);
+		if (is_sub && kr_nsec_children_in_zone_check(bm, bm_size) != 0) {
+			VERBOSE_MSG(qry,
+				"=> NSEC wildcard: covered but delegated (or error)\n");
+			ret = kr_ok();
+			goto clean_wild;
+		}
+		/* We have a record proving wildcard non-existence. */
+		WITH_VERBOSE(qry) {
+			auto_free char *owner_str = kr_dname_text(nsec_rr->owner),
+				*next_str = kr_dname_text(knot_nsec_next(nsec_rr->rrs.rdata));
+			VERBOSE_MSG(qry, "=> NSEC wildcard: covered by: %s -> %s, new TTL %d\n",
+					owner_str, next_str, nsec_rr->ttl);
+		}
+		return AR_SOA;
+	}
+
+	/* The wildcard exists.  Find if it's NODATA - check type bitmap. */
+	if (kr_nsec_bitmap_nodata_check(bm, bm_size, qry->stype, nsec_rr->owner) == 0) {
+		/* NODATA proven; just need to add SOA+RRSIG later */
+		WITH_VERBOSE(qry) {
+			const char *msg_start = "=> NSEC wildcard: match proved NODATA";
+			if (arw->set.rr) {
+				auto_free char *owner_str = kr_dname_text(nsec_rr->owner);
+				VERBOSE_MSG(qry, "%s: %s, new TTL %d\n",
+						msg_start, owner_str, nsec_rr->ttl);
+			} else {
+				/* don't repeat the RR if it's the same */
+				VERBOSE_MSG(qry, "%s, by the same RR\n", msg_start);
+			}
+		}
+		ans->rcode = PKT_NODATA;
+		return AR_SOA;
+
+	} /* else */
+	/* The data probably exists -> don't add this NSEC
+	 * and (later) try to find the real wildcard data */
+	VERBOSE_MSG(qry, "=> NSEC wildcard: should exist (or error)\n");
+	ans->rcode = PKT_NOERROR;
+	ret = kr_ok();
+clean_wild:
+	if (arw->set.rr) { /* we may have matched AR_NSEC */
+		knot_rrset_free(arw->set.rr, ans->mm);
+		arw->set.rr = NULL;
+		knot_rdataset_clear(&arw->sig_rds, ans->mm);
+	}
+	return ret;
+}
+