Adding upstream version 5.6.0.upstream/5.6.0upstream

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

1 files changed, 304 insertions, 0 deletions

diff --git a/lib/dnssec/signature.c b/lib/dnssec/signature.c
new file mode 100644
index 0000000..aadb5cb
--- /dev/null
+++ b/lib/dnssec/signature.c
@@ -0,0 +1,304 @@
+/*  Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <arpa/inet.h>
+#include <string.h>
+
+#include <libdnssec/error.h>
+#include <libdnssec/key.h>
+#include <libdnssec/sign.h>
+#include <libknot/descriptor.h>
+#include <libknot/packet/rrset-wire.h>
+#include <libknot/packet/wire.h>
+#include <libknot/rrset.h>
+#include <libknot/rrtype/rrsig.h>
+#include <libknot/rrtype/ds.h>
+#include <libknot/wire.h>
+
+#include "lib/defines.h"
+#include "lib/utils.h"
+#include "lib/dnssec/signature.h"
+
+static int authenticate_ds(const dnssec_key_t *key, dnssec_binary_t *ds_rdata, uint8_t digest_type)
+{
+	/* Compute DS RDATA from the DNSKEY. */
+	dnssec_binary_t computed_ds = { 0, };
+	int ret = dnssec_key_create_ds(key, digest_type, &computed_ds);
+	if (ret != DNSSEC_EOK)
+		goto fail;
+
+	/* DS records contain algorithm, key tag and the digest.
+	 * Therefore the comparison of the two DS is sufficient.
+	 */
+	ret = (ds_rdata->size == computed_ds.size) &&
+	    (memcmp(ds_rdata->data, computed_ds.data, ds_rdata->size) == 0);
+	ret = ret ? kr_ok() : kr_error(ENOENT);
+
+fail:
+	dnssec_binary_free(&computed_ds);
+	return kr_error(ret);
+}
+
+int kr_authenticate_referral(const knot_rrset_t *ref, const dnssec_key_t *key)
+{
+	if (kr_fails_assert(ref && key))
+		return kr_error(EINVAL);
+	if (ref->type != KNOT_RRTYPE_DS)
+		return kr_error(EINVAL);
+
+	/* Determine whether to ignore SHA1 digests, because:
+	    https://datatracker.ietf.org/doc/html/rfc4509#section-3
+	 * Now, the RFCs seem to only mention SHA1 and SHA256 (e.g. no SHA384),
+	 * but the most natural extension is to make any other algorithm trump SHA1.
+	 * (Note that the old GOST version is already unsupported by libdnssec.) */
+	bool skip_sha1 = false;
+	knot_rdata_t *rd = ref->rrs.rdata;
+	for (int i = 0; i < ref->rrs.count; ++i, rd = knot_rdataset_next(rd)) {
+		const uint8_t algo = knot_ds_digest_type(rd);
+		if (algo != DNSSEC_KEY_DIGEST_SHA1 && dnssec_algorithm_digest_support(algo)) {
+			skip_sha1 = true;
+			break;
+		}
+	}
+	/* But otherwise try all possible DS records. */
+	int ret = 0;
+	rd = ref->rrs.rdata;
+	for (int i = 0; i < ref->rrs.count; ++i, rd = knot_rdataset_next(rd)) {
+		const uint8_t algo = knot_ds_digest_type(rd);
+		if (skip_sha1 && algo == DNSSEC_KEY_DIGEST_SHA1)
+			continue;
+		dnssec_binary_t ds_rdata = {
+			.size = rd->len,
+			.data = rd->data
+		};
+		ret = authenticate_ds(key, &ds_rdata, algo);
+		if (ret == 0) /* Found a good DS */
+			return kr_ok();
+	}
+
+	return kr_error(ret);
+}
+
+/**
+ * Adjust TTL in wire format.
+ * @param wire      RR Set in wire format.
+ * @param wire_size Size of the wire data portion.
+ * @param new_ttl   TTL value to be set for all RRs.
+ * @return          0 or error code.
+ */
+static int adjust_wire_ttl(uint8_t *wire, size_t wire_size, uint32_t new_ttl)
+{
+	if (kr_fails_assert(wire))
+		return kr_error(EINVAL);
+	static_assert(sizeof(uint16_t) == 2, "uint16_t must be exactly 2 bytes");
+	static_assert(sizeof(uint32_t) == 4, "uint32_t must be exactly 4 bytes");
+	uint16_t rdlen;
+
+	int ret;
+
+	new_ttl = htonl(new_ttl);
+
+	size_t i = 0;
+	/* RR wire format in RFC1035 3.2.1 */
+	while(i < wire_size) {
+		ret = knot_dname_size(wire + i);
+		if (ret < 0)
+			return ret;
+		i += ret + 4;
+		memcpy(wire + i, &new_ttl, sizeof(uint32_t));
+		i += sizeof(uint32_t);
+
+		memcpy(&rdlen, wire + i, sizeof(uint16_t));
+		rdlen = ntohs(rdlen);
+		i += sizeof(uint16_t) + rdlen;
+
+		if (kr_fails_assert(i <= wire_size))
+			return kr_error(EINVAL);
+	}
+
+	return kr_ok();
+}
+
+/*!
+ * \brief Add RRSIG RDATA without signature to signing context.
+ *
+ * Requires signer name in RDATA in canonical form.
+ *
+ * \param ctx   Signing context.
+ * \param rdata Pointer to RRSIG RDATA.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+#define RRSIG_RDATA_SIGNER_OFFSET 18
+static int sign_ctx_add_self(dnssec_sign_ctx_t *ctx, const uint8_t *rdata)
+{
+	if (kr_fails_assert(ctx && rdata))
+		return kr_error(EINVAL);
+
+	int result;
+
+	// static header
+
+	dnssec_binary_t header = {
+		.data = (uint8_t *)rdata,
+		.size = RRSIG_RDATA_SIGNER_OFFSET,
+	};
+
+	result = dnssec_sign_add(ctx, &header);
+	if (result != DNSSEC_EOK)
+		return result;
+
+	// signer name
+
+	const uint8_t *rdata_signer = rdata + RRSIG_RDATA_SIGNER_OFFSET;
+	dnssec_binary_t signer = { 0 };
+	signer.data = knot_dname_copy(rdata_signer, NULL);
+	signer.size = knot_dname_size(signer.data);
+
+	result = dnssec_sign_add(ctx, &signer);
+	free(signer.data);
+
+	return result;
+}
+#undef RRSIG_RDATA_SIGNER_OFFSET
+
+/*!
+ * \brief Add covered RRs to signing context.
+ *
+ * Requires all DNAMEs in canonical form and all RRs ordered canonically.
+ *
+ * \param ctx      Signing context.
+ * \param covered  Covered RRs.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+static int sign_ctx_add_records(dnssec_sign_ctx_t *ctx, const knot_rrset_t *covered,
+                                uint32_t orig_ttl, int trim_labels)
+{
+	if (!ctx || !covered || trim_labels < 0)
+		return kr_error(EINVAL);
+
+	// huge block of rrsets can be optionally created
+	static uint8_t wire_buffer[KNOT_WIRE_MAX_PKTSIZE];
+	int written = knot_rrset_to_wire(covered, wire_buffer, sizeof(wire_buffer), NULL);
+	if (written < 0)
+		return written;
+
+	/* Set original ttl. */
+	int ret = adjust_wire_ttl(wire_buffer, written, orig_ttl);
+	if (ret != 0)
+		return ret;
+
+	if (!trim_labels) {
+		const dnssec_binary_t wire_binary = {
+			.size = written,
+			.data = wire_buffer
+		};
+		return dnssec_sign_add(ctx, &wire_binary);
+	}
+
+	/* RFC4035 5.3.2
+	 * Remove leftmost labels and replace them with '*.'
+	 * for each RR in covered.
+	 */
+	uint8_t *beginp = wire_buffer;
+	for (uint16_t i = 0; i < covered->rrs.count; ++i) {
+		/* RR(i) = name | type | class | OrigTTL | RDATA length | RDATA */
+		for (int j = 0; j < trim_labels; ++j) {
+			if (kr_fails_assert(beginp[0]))
+				return kr_error(EINVAL);
+			beginp = (uint8_t *) knot_wire_next_label(beginp, NULL);
+			if (kr_fails_assert(beginp))
+				return kr_error(EFAULT);
+		}
+		*(--beginp) = '*';
+		*(--beginp) = 1;
+		const size_t rdatalen_offset = knot_dname_size(beginp) + /* name */
+			sizeof(uint16_t) + /* type */
+			sizeof(uint16_t) + /* class */
+			sizeof(uint32_t);  /* OrigTTL */
+		const uint8_t *rdatalen_ptr = beginp + rdatalen_offset;
+		const uint16_t rdata_size = knot_wire_read_u16(rdatalen_ptr);
+		const size_t rr_size = rdatalen_offset +
+			sizeof(uint16_t) + /* RDATA length */
+			rdata_size;        /* RDATA */
+		const dnssec_binary_t wire_binary = {
+			.size = rr_size,
+			.data = beginp
+		};
+		ret = dnssec_sign_add(ctx, &wire_binary);
+		if (ret != 0)
+			break;
+		beginp += rr_size;
+	}
+	return ret;
+}
+
+/*!
+ * \brief Add all data covered by signature into signing context.
+ *
+ * RFC 4034: The signature covers RRSIG RDATA field (excluding the signature)
+ * and all matching RR records, which are ordered canonically.
+ *
+ * Requires all DNAMEs in canonical form and all RRs ordered canonically.
+ *
+ * \param ctx          Signing context.
+ * \param rrsig_rdata  RRSIG RDATA with populated fields except signature.
+ * \param covered      Covered RRs.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+/* TODO -- Taken from knot/src/knot/dnssec/rrset-sign.c. Re-write for better fit needed. */
+static int sign_ctx_add_data(dnssec_sign_ctx_t *ctx, const uint8_t *rrsig_rdata,
+                             const knot_rrset_t *covered, uint32_t orig_ttl, int trim_labels)
+{
+	int result = sign_ctx_add_self(ctx, rrsig_rdata);
+	if (result != KNOT_EOK)
+		return result;
+
+	return sign_ctx_add_records(ctx, covered, orig_ttl, trim_labels);
+}
+
+int kr_check_signature(const knot_rdata_t *rrsig,
+                       const dnssec_key_t *key, const knot_rrset_t *covered,
+                       int trim_labels)
+{
+	if (!rrsig || !key || !dnssec_key_can_verify(key))
+		return kr_error(EINVAL);
+
+	int ret = 0;
+	dnssec_sign_ctx_t *sign_ctx = NULL;
+	dnssec_binary_t signature = {
+		.data = /*const-cast*/(uint8_t*)knot_rrsig_signature(rrsig),
+		.size = knot_rrsig_signature_len(rrsig),
+	};
+	if (!signature.data || !signature.size) {
+		ret = kr_error(EINVAL);
+		goto fail;
+	}
+
+	if (dnssec_sign_new(&sign_ctx, key) != 0) {
+		ret = kr_error(ENOMEM);
+		goto fail;
+	}
+
+	uint32_t orig_ttl = knot_rrsig_original_ttl(rrsig);
+
+	if (sign_ctx_add_data(sign_ctx, rrsig->data, covered, orig_ttl, trim_labels) != 0) {
+		ret = kr_error(ENOMEM);
+		goto fail;
+	}
+
+	ret = dnssec_sign_verify(sign_ctx, false, &signature);
+	if (ret != 0) {
+		ret = kr_error(EBADMSG);
+		goto fail;
+	}
+
+	ret = kr_ok();
+
+fail:
+	dnssec_sign_free(sign_ctx);
+	return ret;
+}