1 files changed, 395 insertions, 0 deletions

diff --git a/src/knot/dnssec/rrset-sign.c b/src/knot/dnssec/rrset-sign.c
new file mode 100644
index 0000000..6004ab9
--- /dev/null
+++ b/src/knot/dnssec/rrset-sign.c
@@ -0,0 +1,395 @@
+/*  Copyright (C) 2019 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+
+#include "contrib/wire_ctx.h"
+#include "libdnssec/error.h"
+#include "knot/dnssec/rrset-sign.h"
+#include "knot/dnssec/zone-sign.h"
+#include "libknot/libknot.h"
+
+#define RRSIG_RDATA_SIGNER_OFFSET 18
+
+#define RRSIG_INCEPT_IN_PAST (90 * 60)
+
+/*- Creating of RRSIGs -------------------------------------------------------*/
+
+/*!
+ * \brief Get size of RRSIG RDATA for a given key without signature.
+ */
+static size_t rrsig_rdata_header_size(const dnssec_key_t *key)
+{
+	if (!key) {
+		return 0;
+	}
+
+	size_t size;
+
+	// static part
+
+	size = sizeof(uint16_t)		// type covered
+	     + sizeof(uint8_t)		// algorithm
+	     + sizeof(uint8_t)		// labels
+	     + sizeof(uint32_t)		// original TTL
+	     + sizeof(uint32_t)		// signature expiration
+	     + sizeof(uint32_t)		// signature inception
+	     + sizeof(uint16_t);	// key tag (footprint)
+
+	assert(size == RRSIG_RDATA_SIGNER_OFFSET);
+
+	// variable part
+
+	size += knot_dname_size(dnssec_key_get_dname(key));
+
+	return size;
+}
+
+/*!
+ * \brief Write RRSIG RDATA except signature.
+ *
+ * \note This can be also used for SIG(0) if proper parameters are supplied.
+ *
+ * \param rdata_len     Length of RDATA.
+ * \param rdata         Pointer to RDATA.
+ * \param key           Key used for signing.
+ * \param covered_type  Type of the covered RR.
+ * \param owner_labels  Number of labels covered by the signature.
+ * \param sig_incepted  Timestamp of signature inception.
+ * \param sig_expires   Timestamp of signature expiration.
+ */
+static int rrsig_write_rdata(uint8_t *rdata, size_t rdata_len,
+                             const dnssec_key_t *key,
+                             uint16_t covered_type, uint8_t owner_labels,
+                             uint32_t owner_ttl,  uint32_t sig_incepted,
+                             uint32_t sig_expires)
+{
+	if (!rdata || !key || sig_incepted >= sig_expires) {
+		return KNOT_EINVAL;
+	}
+
+	uint8_t algorithm = dnssec_key_get_algorithm(key);
+	uint16_t keytag = dnssec_key_get_keytag(key);
+	const uint8_t *signer = dnssec_key_get_dname(key);
+	assert(signer);
+
+	wire_ctx_t wire = wire_ctx_init(rdata, rdata_len);
+
+	wire_ctx_write_u16(&wire, covered_type);	// type covered
+	wire_ctx_write_u8(&wire, algorithm);		// algorithm
+	wire_ctx_write_u8(&wire, owner_labels);	// labels
+	wire_ctx_write_u32(&wire, owner_ttl);		// original TTL
+	wire_ctx_write_u32(&wire, sig_expires);	// signature expiration
+	wire_ctx_write_u32(&wire, sig_incepted);	// signature inception
+	wire_ctx_write_u16(&wire, keytag);		// key fingerprint
+	assert(wire_ctx_offset(&wire) == RRSIG_RDATA_SIGNER_OFFSET);
+	wire_ctx_write(&wire, signer, knot_dname_size(signer));	// signer
+
+	return wire.error;
+}
+
+/*- Computation of signatures ------------------------------------------------*/
+
+/*!
+ * \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.
+ */
+static int sign_ctx_add_self(dnssec_sign_ctx_t *ctx, const uint8_t *rdata)
+{
+	assert(ctx);
+	assert(rdata);
+
+	int result;
+
+	// static header
+
+	dnssec_binary_t header = { 0 };
+	header.data = (uint8_t *)rdata;
+	header.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;
+}
+
+/*!
+ * \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)
+{
+	// huge block of rrsets can be optionally created
+	uint8_t *rrwf = malloc(KNOT_WIRE_MAX_PKTSIZE);
+	if (!rrwf) {
+		return KNOT_ENOMEM;
+	}
+
+	int written = knot_rrset_to_wire(covered, rrwf, KNOT_WIRE_MAX_PKTSIZE, NULL);
+	if (written < 0) {
+		free(rrwf);
+		return written;
+	}
+
+	dnssec_binary_t rrset_wire = { 0 };
+	rrset_wire.size = written;
+	rrset_wire.data = rrwf;
+	int result = dnssec_sign_add(ctx, &rrset_wire);
+	free(rrwf);
+
+	return result;
+}
+
+int knot_sign_ctx_add_data(dnssec_sign_ctx_t *ctx,
+                           const uint8_t *rrsig_rdata,
+                           const knot_rrset_t *covered)
+{
+	if (!ctx || !rrsig_rdata || knot_rrset_empty(covered)) {
+		return KNOT_EINVAL;
+	}
+
+	int result = sign_ctx_add_self(ctx, rrsig_rdata);
+	if (result != KNOT_EOK) {
+		return result;
+	}
+
+	return sign_ctx_add_records(ctx, covered);
+}
+
+/*!
+ * \brief Create RRSIG RDATA.
+ *
+ * \param[in]  rrsigs        RR set with RRSIGS.
+ * \param[in]  ctx           DNSSEC signing context.
+ * \param[in]  covered       RR covered by the signature.
+ * \param[in]  key           Key used for signing.
+ * \param[in]  sig_incepted  Timestamp of signature inception.
+ * \param[in]  sig_expires   Timestamp of signature expiration.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+static int rrsigs_create_rdata(knot_rrset_t *rrsigs, dnssec_sign_ctx_t *ctx,
+                               const knot_rrset_t *covered,
+                               const dnssec_key_t *key,
+                               uint32_t sig_incepted, uint32_t sig_expires,
+                               knot_mm_t *mm)
+{
+	assert(rrsigs);
+	assert(rrsigs->type == KNOT_RRTYPE_RRSIG);
+	assert(!knot_rrset_empty(covered));
+	assert(key);
+
+	size_t header_size = rrsig_rdata_header_size(key);
+	assert(header_size != 0);
+
+	uint8_t owner_labels = knot_dname_labels(covered->owner, NULL);
+	if (knot_dname_is_wildcard(covered->owner)) {
+		owner_labels -= 1;
+	}
+
+	uint8_t header[header_size];
+	int res = rrsig_write_rdata(header, header_size,
+	                            key, covered->type, owner_labels,
+	                            covered->ttl, sig_incepted, sig_expires);
+	assert(res == KNOT_EOK);
+
+	res = dnssec_sign_init(ctx);
+	if (res != KNOT_EOK) {
+		return res;
+	}
+
+	res = knot_sign_ctx_add_data(ctx, header, covered);
+	if (res != KNOT_EOK) {
+		return res;
+	}
+
+	dnssec_binary_t signature = { 0 };
+	res = dnssec_sign_write(ctx, &signature);
+	if (res != DNSSEC_EOK) {
+		return res;
+	}
+	assert(signature.size > 0);
+
+	size_t rrsig_size = header_size + signature.size;
+	uint8_t rrsig[rrsig_size];
+	memcpy(rrsig, header, header_size);
+	memcpy(rrsig + header_size, signature.data, signature.size);
+
+	dnssec_binary_free(&signature);
+
+	return knot_rrset_add_rdata(rrsigs, rrsig, rrsig_size, mm);
+}
+
+int knot_sign_rrset(knot_rrset_t *rrsigs, const knot_rrset_t *covered,
+                    const dnssec_key_t *key, dnssec_sign_ctx_t *sign_ctx,
+                    const kdnssec_ctx_t *dnssec_ctx, knot_mm_t *mm, knot_time_t *expires)
+{
+	if (knot_rrset_empty(covered) || !key || !sign_ctx || !dnssec_ctx ||
+	    rrsigs->type != KNOT_RRTYPE_RRSIG ||
+	    !knot_dname_is_equal(rrsigs->owner, covered->owner)
+	) {
+		return KNOT_EINVAL;
+	}
+
+	uint32_t sig_incept = dnssec_ctx->now - RRSIG_INCEPT_IN_PAST;
+	uint32_t sig_expire = dnssec_ctx->now + dnssec_ctx->policy->rrsig_lifetime;
+
+	int ret = rrsigs_create_rdata(rrsigs, sign_ctx, covered, key, sig_incept,
+	                              sig_expire, mm);
+	if (ret == KNOT_EOK && expires != NULL) {
+		*expires = knot_time_min(*expires, sig_expire);
+	}
+	return ret;
+}
+
+int knot_sign_rrset2(knot_rrset_t *rrsigs, const knot_rrset_t *rrset,
+                     zone_sign_ctx_t *sign_ctx, knot_mm_t *mm)
+{
+	if (rrsigs == NULL || rrset == NULL || sign_ctx == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	for (size_t i = 0; i < sign_ctx->count; i++) {
+		zone_key_t *key = &sign_ctx->keys[i];
+
+		if (!knot_zone_sign_use_key(key, rrset)) {
+			continue;
+		}
+
+		int ret = knot_sign_rrset(rrsigs, rrset, key->key, sign_ctx->sign_ctxs[i],
+		                          sign_ctx->dnssec_ctx, mm, NULL);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	}
+
+	return KNOT_EOK;
+}
+
+int knot_synth_rrsig(uint16_t type, const knot_rdataset_t *rrsig_rrs,
+                     knot_rdataset_t *out_sig, knot_mm_t *mm)
+{
+	if (rrsig_rrs == NULL) {
+		return KNOT_ENOENT;
+	}
+
+	if (out_sig == NULL || out_sig->count > 0) {
+		return KNOT_EINVAL;
+	}
+
+	knot_rdata_t *rr_to_copy = rrsig_rrs->rdata;
+	for (int i = 0; i < rrsig_rrs->count; ++i) {
+		if (type == knot_rrsig_type_covered(rr_to_copy)) {
+			int ret = knot_rdataset_add(out_sig, rr_to_copy, mm);
+			if (ret != KNOT_EOK) {
+				knot_rdataset_clear(out_sig, mm);
+				return ret;
+			}
+		}
+		rr_to_copy = knot_rdataset_next(rr_to_copy);
+	}
+
+	return out_sig->count > 0 ? KNOT_EOK : KNOT_ENOENT;
+}
+
+/*- Verification of signatures -----------------------------------------------*/
+
+/*!
+ * \brief Check if the signature is expired.
+ *
+ * \param rrsig   RRSIG rdata.
+ * \param policy  DNSSEC policy.
+ *
+ * \return Signature is expired or should be replaced soon.
+ */
+static bool is_expired_signature(const knot_rdata_t *rrsig, uint32_t now,
+                                 uint32_t refresh_before)
+{
+	assert(rrsig);
+
+	uint32_t expire_at = knot_rrsig_sig_expiration(rrsig);
+	uint32_t expire_in = expire_at > now ? expire_at - now : 0;
+
+	return expire_in <= refresh_before;
+}
+
+int knot_check_signature(const knot_rrset_t *covered,
+                    const knot_rrset_t *rrsigs, size_t pos,
+                    const dnssec_key_t *key,
+                    dnssec_sign_ctx_t *sign_ctx,
+                    const kdnssec_ctx_t *dnssec_ctx)
+{
+	if (knot_rrset_empty(covered) || knot_rrset_empty(rrsigs) || !key ||
+	    !sign_ctx || !dnssec_ctx) {
+		return KNOT_EINVAL;
+	}
+
+	knot_rdata_t *rrsig = knot_rdataset_at(&rrsigs->rrs, pos);
+	assert(rrsig);
+
+	if (is_expired_signature(rrsig, dnssec_ctx->now,
+	                         dnssec_ctx->policy->rrsig_refresh_before)) {
+		return DNSSEC_INVALID_SIGNATURE;
+	}
+
+	// identify fields in the signature being validated
+
+	dnssec_binary_t signature = {
+		.size = knot_rrsig_signature_len(rrsig),
+		.data = (uint8_t *)knot_rrsig_signature(rrsig)
+	};
+	if (signature.data == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// perform the validation
+
+	int result = dnssec_sign_init(sign_ctx);
+	if (result != KNOT_EOK) {
+		return result;
+	}
+
+	result = knot_sign_ctx_add_data(sign_ctx, rrsig->data, covered);
+	if (result != KNOT_EOK) {
+		return result;
+	}
+
+	return dnssec_sign_verify(sign_ctx, &signature);
+}