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-rw-r--r--src/resolve/resolved-dns-dnssec.c2583
1 files changed, 2583 insertions, 0 deletions
diff --git a/src/resolve/resolved-dns-dnssec.c b/src/resolve/resolved-dns-dnssec.c
new file mode 100644
index 0000000..f63cd9b
--- /dev/null
+++ b/src/resolve/resolved-dns-dnssec.c
@@ -0,0 +1,2583 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "alloc-util.h"
+#include "dns-domain.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "gcrypt-util.h"
+#include "hexdecoct.h"
+#include "memory-util.h"
+#include "openssl-util.h"
+#include "resolved-dns-dnssec.h"
+#include "resolved-dns-packet.h"
+#include "sort-util.h"
+#include "string-table.h"
+
+#if PREFER_OPENSSL
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(RSA*, RSA_free, NULL);
+DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(EC_KEY*, EC_KEY_free, NULL);
+# pragma GCC diagnostic pop
+#endif
+
+#define VERIFY_RRS_MAX 256
+#define MAX_KEY_SIZE (32*1024)
+
+/* Permit a maximum clock skew of 1h 10min. This should be enough to deal with DST confusion */
+#define SKEW_MAX (1*USEC_PER_HOUR + 10*USEC_PER_MINUTE)
+
+/* Maximum number of NSEC3 iterations we'll do. RFC5155 says 2500 shall be the maximum useful value */
+#define NSEC3_ITERATIONS_MAX 2500
+
+/*
+ * The DNSSEC Chain of trust:
+ *
+ * Normal RRs are protected via RRSIG RRs in combination with DNSKEY RRs, all in the same zone
+ * DNSKEY RRs are either protected like normal RRs, or via a DS from a zone "higher" up the tree
+ * DS RRs are protected like normal RRs
+ *
+ * Example chain:
+ * Normal RR → RRSIG/DNSKEY+ → DS → RRSIG/DNSKEY+ → DS → ... → DS → RRSIG/DNSKEY+ → DS
+ */
+
+uint16_t dnssec_keytag(DnsResourceRecord *dnskey, bool mask_revoke) {
+ const uint8_t *p;
+ uint32_t sum, f;
+
+ /* The algorithm from RFC 4034, Appendix B. */
+
+ assert(dnskey);
+ assert(dnskey->key->type == DNS_TYPE_DNSKEY);
+
+ f = (uint32_t) dnskey->dnskey.flags;
+
+ if (mask_revoke)
+ f &= ~DNSKEY_FLAG_REVOKE;
+
+ sum = f + ((((uint32_t) dnskey->dnskey.protocol) << 8) + (uint32_t) dnskey->dnskey.algorithm);
+
+ p = dnskey->dnskey.key;
+
+ for (size_t i = 0; i < dnskey->dnskey.key_size; i++)
+ sum += (i & 1) == 0 ? (uint32_t) p[i] << 8 : (uint32_t) p[i];
+
+ sum += (sum >> 16) & UINT32_C(0xFFFF);
+
+ return sum & UINT32_C(0xFFFF);
+}
+
+#if HAVE_OPENSSL_OR_GCRYPT
+
+static int rr_compare(DnsResourceRecord * const *a, DnsResourceRecord * const *b) {
+ const DnsResourceRecord *x = *a, *y = *b;
+ size_t m;
+ int r;
+
+ /* Let's order the RRs according to RFC 4034, Section 6.3 */
+
+ assert(x);
+ assert(x->wire_format);
+ assert(y);
+ assert(y->wire_format);
+
+ m = MIN(DNS_RESOURCE_RECORD_RDATA_SIZE(x), DNS_RESOURCE_RECORD_RDATA_SIZE(y));
+
+ r = memcmp(DNS_RESOURCE_RECORD_RDATA(x), DNS_RESOURCE_RECORD_RDATA(y), m);
+ if (r != 0)
+ return r;
+
+ return CMP(DNS_RESOURCE_RECORD_RDATA_SIZE(x), DNS_RESOURCE_RECORD_RDATA_SIZE(y));
+}
+
+static int dnssec_rsa_verify_raw(
+ hash_algorithm_t hash_algorithm,
+ const void *signature, size_t signature_size,
+ const void *data, size_t data_size,
+ const void *exponent, size_t exponent_size,
+ const void *modulus, size_t modulus_size) {
+ int r;
+
+#if PREFER_OPENSSL
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+ _cleanup_(RSA_freep) RSA *rpubkey = NULL;
+ _cleanup_(EVP_PKEY_freep) EVP_PKEY *epubkey = NULL;
+ _cleanup_(EVP_PKEY_CTX_freep) EVP_PKEY_CTX *ctx = NULL;
+ _cleanup_(BN_freep) BIGNUM *e = NULL, *m = NULL;
+
+ assert(hash_algorithm);
+
+ e = BN_bin2bn(exponent, exponent_size, NULL);
+ if (!e)
+ return -EIO;
+
+ m = BN_bin2bn(modulus, modulus_size, NULL);
+ if (!m)
+ return -EIO;
+
+ rpubkey = RSA_new();
+ if (!rpubkey)
+ return -ENOMEM;
+
+ if (RSA_set0_key(rpubkey, m, e, NULL) <= 0)
+ return -EIO;
+ e = m = NULL;
+
+ assert((size_t) RSA_size(rpubkey) == signature_size);
+
+ epubkey = EVP_PKEY_new();
+ if (!epubkey)
+ return -ENOMEM;
+
+ if (EVP_PKEY_assign_RSA(epubkey, RSAPublicKey_dup(rpubkey)) <= 0)
+ return -EIO;
+
+ ctx = EVP_PKEY_CTX_new(epubkey, NULL);
+ if (!ctx)
+ return -ENOMEM;
+
+ if (EVP_PKEY_verify_init(ctx) <= 0)
+ return -EIO;
+
+ if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
+ return -EIO;
+
+ if (EVP_PKEY_CTX_set_signature_md(ctx, hash_algorithm) <= 0)
+ return -EIO;
+
+ r = EVP_PKEY_verify(ctx, signature, signature_size, data, data_size);
+ if (r < 0)
+ return log_debug_errno(SYNTHETIC_ERRNO(EIO),
+ "Signature verification failed: 0x%lx", ERR_get_error());
+
+# pragma GCC diagnostic pop
+#else
+ gcry_sexp_t public_key_sexp = NULL, data_sexp = NULL, signature_sexp = NULL;
+ gcry_mpi_t n = NULL, e = NULL, s = NULL;
+ gcry_error_t ge;
+
+ assert(hash_algorithm);
+
+ ge = gcry_mpi_scan(&s, GCRYMPI_FMT_USG, signature, signature_size, NULL);
+ if (ge != 0) {
+ r = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_mpi_scan(&e, GCRYMPI_FMT_USG, exponent, exponent_size, NULL);
+ if (ge != 0) {
+ r = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_mpi_scan(&n, GCRYMPI_FMT_USG, modulus, modulus_size, NULL);
+ if (ge != 0) {
+ r = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_sexp_build(&signature_sexp,
+ NULL,
+ "(sig-val (rsa (s %m)))",
+ s);
+
+ if (ge != 0) {
+ r = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_sexp_build(&data_sexp,
+ NULL,
+ "(data (flags pkcs1) (hash %s %b))",
+ hash_algorithm,
+ (int) data_size,
+ data);
+ if (ge != 0) {
+ r = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_sexp_build(&public_key_sexp,
+ NULL,
+ "(public-key (rsa (n %m) (e %m)))",
+ n,
+ e);
+ if (ge != 0) {
+ r = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_pk_verify(signature_sexp, data_sexp, public_key_sexp);
+ if (gpg_err_code(ge) == GPG_ERR_BAD_SIGNATURE)
+ r = 0;
+ else if (ge != 0)
+ r = log_debug_errno(SYNTHETIC_ERRNO(EIO),
+ "RSA signature check failed: %s", gpg_strerror(ge));
+ else
+ r = 1;
+
+finish:
+ if (e)
+ gcry_mpi_release(e);
+ if (n)
+ gcry_mpi_release(n);
+ if (s)
+ gcry_mpi_release(s);
+
+ if (public_key_sexp)
+ gcry_sexp_release(public_key_sexp);
+ if (signature_sexp)
+ gcry_sexp_release(signature_sexp);
+ if (data_sexp)
+ gcry_sexp_release(data_sexp);
+#endif
+ return r;
+}
+
+static int dnssec_rsa_verify(
+ hash_algorithm_t hash_algorithm,
+ const void *hash, size_t hash_size,
+ DnsResourceRecord *rrsig,
+ DnsResourceRecord *dnskey) {
+
+ size_t exponent_size, modulus_size;
+ void *exponent, *modulus;
+
+ assert(hash_algorithm);
+ assert(hash);
+ assert(hash_size > 0);
+ assert(rrsig);
+ assert(dnskey);
+
+ if (*(uint8_t*) dnskey->dnskey.key == 0) {
+ /* exponent is > 255 bytes long */
+
+ exponent = (uint8_t*) dnskey->dnskey.key + 3;
+ exponent_size =
+ ((size_t) (((uint8_t*) dnskey->dnskey.key)[1]) << 8) |
+ ((size_t) ((uint8_t*) dnskey->dnskey.key)[2]);
+
+ if (exponent_size < 256)
+ return -EINVAL;
+
+ if (3 + exponent_size >= dnskey->dnskey.key_size)
+ return -EINVAL;
+
+ modulus = (uint8_t*) dnskey->dnskey.key + 3 + exponent_size;
+ modulus_size = dnskey->dnskey.key_size - 3 - exponent_size;
+
+ } else {
+ /* exponent is <= 255 bytes long */
+
+ exponent = (uint8_t*) dnskey->dnskey.key + 1;
+ exponent_size = (size_t) ((uint8_t*) dnskey->dnskey.key)[0];
+
+ if (exponent_size <= 0)
+ return -EINVAL;
+
+ if (1 + exponent_size >= dnskey->dnskey.key_size)
+ return -EINVAL;
+
+ modulus = (uint8_t*) dnskey->dnskey.key + 1 + exponent_size;
+ modulus_size = dnskey->dnskey.key_size - 1 - exponent_size;
+ }
+
+ return dnssec_rsa_verify_raw(
+ hash_algorithm,
+ rrsig->rrsig.signature, rrsig->rrsig.signature_size,
+ hash, hash_size,
+ exponent, exponent_size,
+ modulus, modulus_size);
+}
+
+static int dnssec_ecdsa_verify_raw(
+ hash_algorithm_t hash_algorithm,
+ elliptic_curve_t curve,
+ const void *signature_r, size_t signature_r_size,
+ const void *signature_s, size_t signature_s_size,
+ const void *data, size_t data_size,
+ const void *key, size_t key_size) {
+ int k;
+
+#if PREFER_OPENSSL
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+ _cleanup_(EC_GROUP_freep) EC_GROUP *ec_group = NULL;
+ _cleanup_(EC_POINT_freep) EC_POINT *p = NULL;
+ _cleanup_(EC_KEY_freep) EC_KEY *eckey = NULL;
+ _cleanup_(BN_CTX_freep) BN_CTX *bctx = NULL;
+ _cleanup_(BN_freep) BIGNUM *r = NULL, *s = NULL;
+ _cleanup_(ECDSA_SIG_freep) ECDSA_SIG *sig = NULL;
+
+ assert(hash_algorithm);
+
+ ec_group = EC_GROUP_new_by_curve_name(curve);
+ if (!ec_group)
+ return -ENOMEM;
+
+ p = EC_POINT_new(ec_group);
+ if (!p)
+ return -ENOMEM;
+
+ bctx = BN_CTX_new();
+ if (!bctx)
+ return -ENOMEM;
+
+ if (EC_POINT_oct2point(ec_group, p, key, key_size, bctx) <= 0)
+ return -EIO;
+
+ eckey = EC_KEY_new();
+ if (!eckey)
+ return -ENOMEM;
+
+ if (EC_KEY_set_group(eckey, ec_group) <= 0)
+ return -EIO;
+
+ if (EC_KEY_set_public_key(eckey, p) <= 0)
+ return log_debug_errno(SYNTHETIC_ERRNO(EIO),
+ "EC_POINT_bn2point failed: 0x%lx", ERR_get_error());
+
+ assert(EC_KEY_check_key(eckey) == 1);
+
+ r = BN_bin2bn(signature_r, signature_r_size, NULL);
+ if (!r)
+ return -EIO;
+
+ s = BN_bin2bn(signature_s, signature_s_size, NULL);
+ if (!s)
+ return -EIO;
+
+ /* TODO: We should eventually use use the EVP API once it supports ECDSA signature verification */
+
+ sig = ECDSA_SIG_new();
+ if (!sig)
+ return -ENOMEM;
+
+ if (ECDSA_SIG_set0(sig, r, s) <= 0)
+ return -EIO;
+ r = s = NULL;
+
+ k = ECDSA_do_verify(data, data_size, sig, eckey);
+ if (k < 0)
+ return log_debug_errno(SYNTHETIC_ERRNO(EIO),
+ "Signature verification failed: 0x%lx", ERR_get_error());
+
+# pragma GCC diagnostic pop
+#else
+ gcry_sexp_t public_key_sexp = NULL, data_sexp = NULL, signature_sexp = NULL;
+ gcry_mpi_t q = NULL, r = NULL, s = NULL;
+ gcry_error_t ge;
+
+ assert(hash_algorithm);
+
+ ge = gcry_mpi_scan(&r, GCRYMPI_FMT_USG, signature_r, signature_r_size, NULL);
+ if (ge != 0) {
+ k = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_mpi_scan(&s, GCRYMPI_FMT_USG, signature_s, signature_s_size, NULL);
+ if (ge != 0) {
+ k = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_mpi_scan(&q, GCRYMPI_FMT_USG, key, key_size, NULL);
+ if (ge != 0) {
+ k = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_sexp_build(&signature_sexp,
+ NULL,
+ "(sig-val (ecdsa (r %m) (s %m)))",
+ r,
+ s);
+ if (ge != 0) {
+ k = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_sexp_build(&data_sexp,
+ NULL,
+ "(data (flags rfc6979) (hash %s %b))",
+ hash_algorithm,
+ (int) data_size,
+ data);
+ if (ge != 0) {
+ k = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_sexp_build(&public_key_sexp,
+ NULL,
+ "(public-key (ecc (curve %s) (q %m)))",
+ curve,
+ q);
+ if (ge != 0) {
+ k = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_pk_verify(signature_sexp, data_sexp, public_key_sexp);
+ if (gpg_err_code(ge) == GPG_ERR_BAD_SIGNATURE)
+ k = 0;
+ else if (ge != 0) {
+ log_debug("ECDSA signature check failed: %s", gpg_strerror(ge));
+ k = -EIO;
+ } else
+ k = 1;
+finish:
+ if (r)
+ gcry_mpi_release(r);
+ if (s)
+ gcry_mpi_release(s);
+ if (q)
+ gcry_mpi_release(q);
+
+ if (public_key_sexp)
+ gcry_sexp_release(public_key_sexp);
+ if (signature_sexp)
+ gcry_sexp_release(signature_sexp);
+ if (data_sexp)
+ gcry_sexp_release(data_sexp);
+#endif
+ return k;
+}
+
+static int dnssec_ecdsa_verify(
+ hash_algorithm_t hash_algorithm,
+ int algorithm,
+ const void *hash, size_t hash_size,
+ DnsResourceRecord *rrsig,
+ DnsResourceRecord *dnskey) {
+
+ elliptic_curve_t curve;
+ size_t key_size;
+ uint8_t *q;
+
+ assert(hash);
+ assert(hash_size);
+ assert(rrsig);
+ assert(dnskey);
+
+ if (algorithm == DNSSEC_ALGORITHM_ECDSAP256SHA256) {
+ curve = OPENSSL_OR_GCRYPT(NID_X9_62_prime256v1, "NIST P-256"); /* NIST P-256 */
+ key_size = 32;
+ } else if (algorithm == DNSSEC_ALGORITHM_ECDSAP384SHA384) {
+ curve = OPENSSL_OR_GCRYPT(NID_secp384r1, "NIST P-384"); /* NIST P-384 */
+ key_size = 48;
+ } else
+ return -EOPNOTSUPP;
+
+ if (dnskey->dnskey.key_size != key_size * 2)
+ return -EINVAL;
+
+ if (rrsig->rrsig.signature_size != key_size * 2)
+ return -EINVAL;
+
+ q = newa(uint8_t, key_size*2 + 1);
+ q[0] = 0x04; /* Prepend 0x04 to indicate an uncompressed key */
+ memcpy(q+1, dnskey->dnskey.key, key_size*2);
+
+ return dnssec_ecdsa_verify_raw(
+ hash_algorithm,
+ curve,
+ rrsig->rrsig.signature, key_size,
+ (uint8_t*) rrsig->rrsig.signature + key_size, key_size,
+ hash, hash_size,
+ q, key_size*2+1);
+}
+
+static int dnssec_eddsa_verify_raw(
+ elliptic_curve_t curve,
+ const uint8_t *signature, size_t signature_size,
+ const uint8_t *data, size_t data_size,
+ const uint8_t *key, size_t key_size) {
+
+#if PREFER_OPENSSL
+ _cleanup_(EVP_PKEY_freep) EVP_PKEY *evkey = NULL;
+ _cleanup_(EVP_PKEY_CTX_freep) EVP_PKEY_CTX *pctx = NULL;
+ _cleanup_(EVP_MD_CTX_freep) EVP_MD_CTX *ctx = NULL;
+ int r;
+
+ assert(curve == NID_ED25519);
+ assert(signature_size == key_size * 2);
+
+ uint8_t *q = newa(uint8_t, signature_size + 1);
+ q[0] = 0x04; /* Prepend 0x04 to indicate an uncompressed key */
+ memcpy(q+1, signature, signature_size);
+
+ evkey = EVP_PKEY_new_raw_public_key(EVP_PKEY_ED25519, NULL, key, key_size);
+ if (!evkey)
+ return log_debug_errno(SYNTHETIC_ERRNO(EIO),
+ "EVP_PKEY_new_raw_public_key failed: 0x%lx", ERR_get_error());
+
+ pctx = EVP_PKEY_CTX_new(evkey, NULL);
+ if (!pctx)
+ return -ENOMEM;
+
+ ctx = EVP_MD_CTX_new();
+ if (!ctx)
+ return -ENOMEM;
+
+ /* This prevents EVP_DigestVerifyInit from managing pctx and complicating our free logic. */
+ EVP_MD_CTX_set_pkey_ctx(ctx, pctx);
+
+ /* One might be tempted to use EVP_PKEY_verify_init, but see Ed25519(7ssl). */
+ if (EVP_DigestVerifyInit(ctx, &pctx, NULL, NULL, evkey) <= 0)
+ return -EIO;
+
+ r = EVP_DigestVerify(ctx, signature, signature_size, data, data_size);
+ if (r < 0)
+ return log_debug_errno(SYNTHETIC_ERRNO(EIO),
+ "Signature verification failed: 0x%lx", ERR_get_error());
+
+ return r;
+
+#elif GCRYPT_VERSION_NUMBER >= 0x010600
+ gcry_sexp_t public_key_sexp = NULL, data_sexp = NULL, signature_sexp = NULL;
+ gcry_error_t ge;
+ int k;
+
+ assert(signature_size == key_size * 2);
+
+ ge = gcry_sexp_build(&signature_sexp,
+ NULL,
+ "(sig-val (eddsa (r %b) (s %b)))",
+ (int) key_size,
+ signature,
+ (int) key_size,
+ signature + key_size);
+ if (ge != 0) {
+ k = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_sexp_build(&data_sexp,
+ NULL,
+ "(data (flags eddsa) (hash-algo sha512) (value %b))",
+ (int) data_size,
+ data);
+ if (ge != 0) {
+ k = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_sexp_build(&public_key_sexp,
+ NULL,
+ "(public-key (ecc (curve %s) (flags eddsa) (q %b)))",
+ curve,
+ (int) key_size,
+ key);
+ if (ge != 0) {
+ k = -EIO;
+ goto finish;
+ }
+
+ ge = gcry_pk_verify(signature_sexp, data_sexp, public_key_sexp);
+ if (gpg_err_code(ge) == GPG_ERR_BAD_SIGNATURE)
+ k = 0;
+ else if (ge != 0)
+ k = log_debug_errno(SYNTHETIC_ERRNO(EIO),
+ "EdDSA signature check failed: %s", gpg_strerror(ge));
+ else
+ k = 1;
+finish:
+ if (public_key_sexp)
+ gcry_sexp_release(public_key_sexp);
+ if (signature_sexp)
+ gcry_sexp_release(signature_sexp);
+ if (data_sexp)
+ gcry_sexp_release(data_sexp);
+
+ return k;
+#else
+ return -EOPNOTSUPP;
+#endif
+}
+
+static int dnssec_eddsa_verify(
+ int algorithm,
+ const void *data, size_t data_size,
+ DnsResourceRecord *rrsig,
+ DnsResourceRecord *dnskey) {
+ elliptic_curve_t curve;
+ size_t key_size;
+
+ if (algorithm == DNSSEC_ALGORITHM_ED25519) {
+ curve = OPENSSL_OR_GCRYPT(NID_ED25519, "Ed25519");
+ key_size = 32;
+ } else
+ return -EOPNOTSUPP;
+
+ if (dnskey->dnskey.key_size != key_size)
+ return -EINVAL;
+
+ if (rrsig->rrsig.signature_size != key_size * 2)
+ return -EINVAL;
+
+ return dnssec_eddsa_verify_raw(
+ curve,
+ rrsig->rrsig.signature, rrsig->rrsig.signature_size,
+ data, data_size,
+ dnskey->dnskey.key, key_size);
+}
+
+static int md_add_uint8(hash_context_t ctx, uint8_t v) {
+#if PREFER_OPENSSL
+ return EVP_DigestUpdate(ctx, &v, sizeof(v));
+#else
+ gcry_md_write(ctx, &v, sizeof(v));
+ return 0;
+#endif
+}
+
+static int md_add_uint16(hash_context_t ctx, uint16_t v) {
+ v = htobe16(v);
+#if PREFER_OPENSSL
+ return EVP_DigestUpdate(ctx, &v, sizeof(v));
+#else
+ gcry_md_write(ctx, &v, sizeof(v));
+ return 0;
+#endif
+}
+
+static void fwrite_uint8(FILE *fp, uint8_t v) {
+ fwrite(&v, sizeof(v), 1, fp);
+}
+
+static void fwrite_uint16(FILE *fp, uint16_t v) {
+ v = htobe16(v);
+ fwrite(&v, sizeof(v), 1, fp);
+}
+
+static void fwrite_uint32(FILE *fp, uint32_t v) {
+ v = htobe32(v);
+ fwrite(&v, sizeof(v), 1, fp);
+}
+
+static int dnssec_rrsig_prepare(DnsResourceRecord *rrsig) {
+ int n_key_labels, n_signer_labels;
+ const char *name;
+ int r;
+
+ /* Checks whether the specified RRSIG RR is somewhat valid, and initializes the .n_skip_labels_source
+ * and .n_skip_labels_signer fields so that we can use them later on. */
+
+ assert(rrsig);
+ assert(rrsig->key->type == DNS_TYPE_RRSIG);
+
+ /* Check if this RRSIG RR is already prepared */
+ if (rrsig->n_skip_labels_source != UINT8_MAX)
+ return 0;
+
+ if (rrsig->rrsig.inception > rrsig->rrsig.expiration)
+ return -EINVAL;
+
+ name = dns_resource_key_name(rrsig->key);
+
+ n_key_labels = dns_name_count_labels(name);
+ if (n_key_labels < 0)
+ return n_key_labels;
+ if (rrsig->rrsig.labels > n_key_labels)
+ return -EINVAL;
+
+ n_signer_labels = dns_name_count_labels(rrsig->rrsig.signer);
+ if (n_signer_labels < 0)
+ return n_signer_labels;
+ if (n_signer_labels > rrsig->rrsig.labels)
+ return -EINVAL;
+
+ r = dns_name_skip(name, n_key_labels - n_signer_labels, &name);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return -EINVAL;
+
+ /* Check if the signer is really a suffix of us */
+ r = dns_name_equal(name, rrsig->rrsig.signer);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return -EINVAL;
+
+ assert(n_key_labels < UINT8_MAX); /* UINT8_MAX/-1 means unsigned. */
+ rrsig->n_skip_labels_source = n_key_labels - rrsig->rrsig.labels;
+ rrsig->n_skip_labels_signer = n_key_labels - n_signer_labels;
+
+ return 0;
+}
+
+static int dnssec_rrsig_expired(DnsResourceRecord *rrsig, usec_t realtime) {
+ usec_t expiration, inception, skew;
+
+ assert(rrsig);
+ assert(rrsig->key->type == DNS_TYPE_RRSIG);
+
+ if (realtime == USEC_INFINITY)
+ realtime = now(CLOCK_REALTIME);
+
+ expiration = rrsig->rrsig.expiration * USEC_PER_SEC;
+ inception = rrsig->rrsig.inception * USEC_PER_SEC;
+
+ /* Consider inverted validity intervals as expired */
+ if (inception > expiration)
+ return true;
+
+ /* Permit a certain amount of clock skew of 10% of the valid
+ * time range. This takes inspiration from unbound's
+ * resolver. */
+ skew = (expiration - inception) / 10;
+ if (skew > SKEW_MAX)
+ skew = SKEW_MAX;
+
+ if (inception < skew)
+ inception = 0;
+ else
+ inception -= skew;
+
+ if (expiration + skew < expiration)
+ expiration = USEC_INFINITY;
+ else
+ expiration += skew;
+
+ return realtime < inception || realtime > expiration;
+}
+
+static hash_md_t algorithm_to_implementation_id(uint8_t algorithm) {
+
+ /* Translates a DNSSEC signature algorithm into an openssl/gcrypt digest identifier.
+ *
+ * Note that we implement all algorithms listed as "Must implement" and "Recommended to Implement" in
+ * RFC6944. We don't implement any algorithms that are listed as "Optional" or "Must Not Implement".
+ * Specifically, we do not implement RSAMD5, DSASHA1, DH, DSA-NSEC3-SHA1, and GOST-ECC. */
+
+ switch (algorithm) {
+
+ case DNSSEC_ALGORITHM_RSASHA1:
+ case DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1:
+ return OPENSSL_OR_GCRYPT(EVP_sha1(), GCRY_MD_SHA1);
+
+ case DNSSEC_ALGORITHM_RSASHA256:
+ case DNSSEC_ALGORITHM_ECDSAP256SHA256:
+ return OPENSSL_OR_GCRYPT(EVP_sha256(), GCRY_MD_SHA256);
+
+ case DNSSEC_ALGORITHM_ECDSAP384SHA384:
+ return OPENSSL_OR_GCRYPT(EVP_sha384(), GCRY_MD_SHA384);
+
+ case DNSSEC_ALGORITHM_RSASHA512:
+ return OPENSSL_OR_GCRYPT(EVP_sha512(), GCRY_MD_SHA512);
+
+ default:
+ return OPENSSL_OR_GCRYPT(NULL, -EOPNOTSUPP);
+ }
+}
+
+static void dnssec_fix_rrset_ttl(
+ DnsResourceRecord *list[],
+ unsigned n,
+ DnsResourceRecord *rrsig) {
+
+ assert(list);
+ assert(n > 0);
+ assert(rrsig);
+
+ for (unsigned k = 0; k < n; k++) {
+ DnsResourceRecord *rr = list[k];
+
+ /* Pick the TTL as the minimum of the RR's TTL, the
+ * RR's original TTL according to the RRSIG and the
+ * RRSIG's own TTL, see RFC 4035, Section 5.3.3 */
+ rr->ttl = MIN3(rr->ttl, rrsig->rrsig.original_ttl, rrsig->ttl);
+ rr->expiry = rrsig->rrsig.expiration * USEC_PER_SEC;
+
+ /* Copy over information about the signer and wildcard source of synthesis */
+ rr->n_skip_labels_source = rrsig->n_skip_labels_source;
+ rr->n_skip_labels_signer = rrsig->n_skip_labels_signer;
+ }
+
+ rrsig->expiry = rrsig->rrsig.expiration * USEC_PER_SEC;
+}
+
+static int dnssec_rrset_serialize_sig(
+ DnsResourceRecord *rrsig,
+ const char *source,
+ DnsResourceRecord **list,
+ size_t list_len,
+ bool wildcard,
+ char **ret_sig_data,
+ size_t *ret_sig_size) {
+
+ _cleanup_free_ char *sig_data = NULL;
+ size_t sig_size = 0;
+ _cleanup_fclose_ FILE *f = NULL;
+ uint8_t wire_format_name[DNS_WIRE_FORMAT_HOSTNAME_MAX];
+ DnsResourceRecord *rr;
+ int r;
+
+ assert(rrsig);
+ assert(source);
+ assert(list || list_len == 0);
+ assert(ret_sig_data);
+ assert(ret_sig_size);
+
+ f = open_memstream_unlocked(&sig_data, &sig_size);
+ if (!f)
+ return -ENOMEM;
+
+ fwrite_uint16(f, rrsig->rrsig.type_covered);
+ fwrite_uint8(f, rrsig->rrsig.algorithm);
+ fwrite_uint8(f, rrsig->rrsig.labels);
+ fwrite_uint32(f, rrsig->rrsig.original_ttl);
+ fwrite_uint32(f, rrsig->rrsig.expiration);
+ fwrite_uint32(f, rrsig->rrsig.inception);
+ fwrite_uint16(f, rrsig->rrsig.key_tag);
+
+ r = dns_name_to_wire_format(rrsig->rrsig.signer, wire_format_name, sizeof(wire_format_name), true);
+ if (r < 0)
+ return r;
+ fwrite(wire_format_name, 1, r, f);
+
+ /* Convert the source of synthesis into wire format */
+ r = dns_name_to_wire_format(source, wire_format_name, sizeof(wire_format_name), true);
+ if (r < 0)
+ return r;
+
+ for (size_t k = 0; k < list_len; k++) {
+ size_t l;
+
+ rr = list[k];
+
+ /* Hash the source of synthesis. If this is a wildcard, then prefix it with the *. label */
+ if (wildcard)
+ fwrite((uint8_t[]) { 1, '*'}, sizeof(uint8_t), 2, f);
+ fwrite(wire_format_name, 1, r, f);
+
+ fwrite_uint16(f, rr->key->type);
+ fwrite_uint16(f, rr->key->class);
+ fwrite_uint32(f, rrsig->rrsig.original_ttl);
+
+ l = DNS_RESOURCE_RECORD_RDATA_SIZE(rr);
+ assert(l <= 0xFFFF);
+
+ fwrite_uint16(f, (uint16_t) l);
+ fwrite(DNS_RESOURCE_RECORD_RDATA(rr), 1, l, f);
+ }
+
+ r = fflush_and_check(f);
+ f = safe_fclose(f); /* sig_data may be reallocated when f is closed. */
+ if (r < 0)
+ return r;
+
+ *ret_sig_data = TAKE_PTR(sig_data);
+ *ret_sig_size = sig_size;
+ return 0;
+}
+
+static int dnssec_rrset_verify_sig(
+ DnsResourceRecord *rrsig,
+ DnsResourceRecord *dnskey,
+ const char *sig_data,
+ size_t sig_size) {
+
+ assert(rrsig);
+ assert(dnskey);
+ assert(sig_data);
+ assert(sig_size > 0);
+
+ hash_md_t md_algorithm;
+
+#if PREFER_OPENSSL
+ uint8_t hash[EVP_MAX_MD_SIZE];
+ unsigned hash_size;
+#else
+ _cleanup_(gcry_md_closep) gcry_md_hd_t md = NULL;
+ void *hash;
+ size_t hash_size;
+
+ initialize_libgcrypt(false);
+#endif
+
+ switch (rrsig->rrsig.algorithm) {
+ case DNSSEC_ALGORITHM_ED25519:
+#if PREFER_OPENSSL || GCRYPT_VERSION_NUMBER >= 0x010600
+ return dnssec_eddsa_verify(
+ rrsig->rrsig.algorithm,
+ sig_data, sig_size,
+ rrsig,
+ dnskey);
+#endif
+ case DNSSEC_ALGORITHM_ED448:
+ return -EOPNOTSUPP;
+ default:
+ /* OK, the RRs are now in canonical order. Let's calculate the digest */
+ md_algorithm = algorithm_to_implementation_id(rrsig->rrsig.algorithm);
+#if PREFER_OPENSSL
+ if (!md_algorithm)
+ return -EOPNOTSUPP;
+
+ _cleanup_(EVP_MD_CTX_freep) EVP_MD_CTX *ctx = EVP_MD_CTX_new();
+ if (!ctx)
+ return -ENOMEM;
+
+ if (EVP_DigestInit_ex(ctx, md_algorithm, NULL) <= 0)
+ return -EIO;
+
+ if (EVP_DigestUpdate(ctx, sig_data, sig_size) <= 0)
+ return -EIO;
+
+ if (EVP_DigestFinal_ex(ctx, hash, &hash_size) <= 0)
+ return -EIO;
+
+ assert(hash_size > 0);
+
+#else
+ if (md_algorithm < 0)
+ return md_algorithm;
+
+ gcry_error_t err = gcry_md_open(&md, md_algorithm, 0);
+ if (gcry_err_code(err) != GPG_ERR_NO_ERROR || !md)
+ return -EIO;
+
+ hash_size = gcry_md_get_algo_dlen(md_algorithm);
+ assert(hash_size > 0);
+
+ gcry_md_write(md, sig_data, sig_size);
+
+ hash = gcry_md_read(md, 0);
+ if (!hash)
+ return -EIO;
+#endif
+ }
+
+ switch (rrsig->rrsig.algorithm) {
+
+ case DNSSEC_ALGORITHM_RSASHA1:
+ case DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1:
+ case DNSSEC_ALGORITHM_RSASHA256:
+ case DNSSEC_ALGORITHM_RSASHA512:
+ return dnssec_rsa_verify(
+ OPENSSL_OR_GCRYPT(md_algorithm, gcry_md_algo_name(md_algorithm)),
+ hash, hash_size,
+ rrsig,
+ dnskey);
+
+ case DNSSEC_ALGORITHM_ECDSAP256SHA256:
+ case DNSSEC_ALGORITHM_ECDSAP384SHA384:
+ return dnssec_ecdsa_verify(
+ OPENSSL_OR_GCRYPT(md_algorithm, gcry_md_algo_name(md_algorithm)),
+ rrsig->rrsig.algorithm,
+ hash, hash_size,
+ rrsig,
+ dnskey);
+
+ default:
+ assert_not_reached();
+ }
+}
+
+int dnssec_verify_rrset(
+ DnsAnswer *a,
+ const DnsResourceKey *key,
+ DnsResourceRecord *rrsig,
+ DnsResourceRecord *dnskey,
+ usec_t realtime,
+ DnssecResult *result) {
+
+ DnsResourceRecord **list, *rr;
+ const char *source, *name;
+ _cleanup_free_ char *sig_data = NULL;
+ size_t sig_size = 0; /* avoid false maybe-uninitialized warning */
+ size_t n = 0;
+ bool wildcard;
+ int r;
+
+ assert(key);
+ assert(rrsig);
+ assert(dnskey);
+ assert(result);
+ assert(rrsig->key->type == DNS_TYPE_RRSIG);
+ assert(dnskey->key->type == DNS_TYPE_DNSKEY);
+
+ /* Verifies that the RRSet matches the specified "key" in "a",
+ * using the signature "rrsig" and the key "dnskey". It's
+ * assumed that RRSIG and DNSKEY match. */
+
+ r = dnssec_rrsig_prepare(rrsig);
+ if (r == -EINVAL) {
+ *result = DNSSEC_INVALID;
+ return r;
+ }
+ if (r < 0)
+ return r;
+
+ r = dnssec_rrsig_expired(rrsig, realtime);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ *result = DNSSEC_SIGNATURE_EXPIRED;
+ return 0;
+ }
+
+ name = dns_resource_key_name(key);
+
+ /* Some keys may only appear signed in the zone apex, and are invalid anywhere else. (SOA, NS...) */
+ if (dns_type_apex_only(rrsig->rrsig.type_covered)) {
+ r = dns_name_equal(rrsig->rrsig.signer, name);
+ if (r < 0)
+ return r;
+ if (r == 0) {
+ *result = DNSSEC_INVALID;
+ return 0;
+ }
+ }
+
+ /* OTOH DS RRs may not appear in the zone apex, but are valid everywhere else. */
+ if (rrsig->rrsig.type_covered == DNS_TYPE_DS) {
+ r = dns_name_equal(rrsig->rrsig.signer, name);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ *result = DNSSEC_INVALID;
+ return 0;
+ }
+ }
+
+ /* Determine the "Source of Synthesis" and whether this is a wildcard RRSIG */
+ r = dns_name_suffix(name, rrsig->rrsig.labels, &source);
+ if (r < 0)
+ return r;
+ if (r > 0 && !dns_type_may_wildcard(rrsig->rrsig.type_covered)) {
+ /* We refuse to validate NSEC3 or SOA RRs that are synthesized from wildcards */
+ *result = DNSSEC_INVALID;
+ return 0;
+ }
+ if (r == 1) {
+ /* If we stripped a single label, then let's see if that maybe was "*". If so, we are not really
+ * synthesized from a wildcard, we are the wildcard itself. Treat that like a normal name. */
+ r = dns_name_startswith(name, "*");
+ if (r < 0)
+ return r;
+ if (r > 0)
+ source = name;
+
+ wildcard = r == 0;
+ } else
+ wildcard = r > 0;
+
+ /* Collect all relevant RRs in a single array, so that we can look at the RRset */
+ list = newa(DnsResourceRecord *, dns_answer_size(a));
+
+ DNS_ANSWER_FOREACH(rr, a) {
+ r = dns_resource_key_equal(key, rr->key);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ /* We need the wire format for ordering, and digest calculation */
+ r = dns_resource_record_to_wire_format(rr, true);
+ if (r < 0)
+ return r;
+
+ list[n++] = rr;
+
+ if (n > VERIFY_RRS_MAX)
+ return -E2BIG;
+ }
+
+ if (n <= 0)
+ return -ENODATA;
+
+ /* Bring the RRs into canonical order */
+ typesafe_qsort(list, n, rr_compare);
+
+ r = dnssec_rrset_serialize_sig(rrsig, source, list, n, wildcard,
+ &sig_data, &sig_size);
+ if (r < 0)
+ return r;
+
+ r = dnssec_rrset_verify_sig(rrsig, dnskey, sig_data, sig_size);
+ if (r == -EOPNOTSUPP) {
+ *result = DNSSEC_UNSUPPORTED_ALGORITHM;
+ return 0;
+ }
+ if (r < 0)
+ return r;
+
+ /* Now, fix the ttl, expiry, and remember the synthesizing source and the signer */
+ if (r > 0)
+ dnssec_fix_rrset_ttl(list, n, rrsig);
+
+ if (r == 0)
+ *result = DNSSEC_INVALID;
+ else if (wildcard)
+ *result = DNSSEC_VALIDATED_WILDCARD;
+ else
+ *result = DNSSEC_VALIDATED;
+
+ return 0;
+}
+
+int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey, bool revoked_ok) {
+
+ assert(rrsig);
+ assert(dnskey);
+
+ /* Checks if the specified DNSKEY RR matches the key used for
+ * the signature in the specified RRSIG RR */
+
+ if (rrsig->key->type != DNS_TYPE_RRSIG)
+ return -EINVAL;
+
+ if (dnskey->key->type != DNS_TYPE_DNSKEY)
+ return 0;
+ if (dnskey->key->class != rrsig->key->class)
+ return 0;
+ if ((dnskey->dnskey.flags & DNSKEY_FLAG_ZONE_KEY) == 0)
+ return 0;
+ if (!revoked_ok && (dnskey->dnskey.flags & DNSKEY_FLAG_REVOKE))
+ return 0;
+ if (dnskey->dnskey.protocol != 3)
+ return 0;
+ if (dnskey->dnskey.algorithm != rrsig->rrsig.algorithm)
+ return 0;
+
+ if (dnssec_keytag(dnskey, false) != rrsig->rrsig.key_tag)
+ return 0;
+
+ return dns_name_equal(dns_resource_key_name(dnskey->key), rrsig->rrsig.signer);
+}
+
+int dnssec_key_match_rrsig(const DnsResourceKey *key, DnsResourceRecord *rrsig) {
+ assert(key);
+ assert(rrsig);
+
+ /* Checks if the specified RRSIG RR protects the RRSet of the specified RR key. */
+
+ if (rrsig->key->type != DNS_TYPE_RRSIG)
+ return 0;
+ if (rrsig->key->class != key->class)
+ return 0;
+ if (rrsig->rrsig.type_covered != key->type)
+ return 0;
+
+ return dns_name_equal(dns_resource_key_name(rrsig->key), dns_resource_key_name(key));
+}
+
+int dnssec_verify_rrset_search(
+ DnsAnswer *a,
+ const DnsResourceKey *key,
+ DnsAnswer *validated_dnskeys,
+ usec_t realtime,
+ DnssecResult *result,
+ DnsResourceRecord **ret_rrsig) {
+
+ bool found_rrsig = false, found_invalid = false, found_expired_rrsig = false, found_unsupported_algorithm = false;
+ DnsResourceRecord *rrsig;
+ int r;
+
+ assert(key);
+ assert(result);
+
+ /* Verifies all RRs from "a" that match the key "key" against DNSKEYs in "validated_dnskeys" */
+
+ if (dns_answer_isempty(a))
+ return -ENODATA;
+
+ /* Iterate through each RRSIG RR. */
+ DNS_ANSWER_FOREACH(rrsig, a) {
+ DnsResourceRecord *dnskey;
+ DnsAnswerFlags flags;
+
+ /* Is this an RRSIG RR that applies to RRs matching our key? */
+ r = dnssec_key_match_rrsig(key, rrsig);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ found_rrsig = true;
+
+ /* Look for a matching key */
+ DNS_ANSWER_FOREACH_FLAGS(dnskey, flags, validated_dnskeys) {
+ DnssecResult one_result;
+
+ if ((flags & DNS_ANSWER_AUTHENTICATED) == 0)
+ continue;
+
+ /* Is this a DNSKEY RR that matches they key of our RRSIG? */
+ r = dnssec_rrsig_match_dnskey(rrsig, dnskey, false);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ /* Take the time here, if it isn't set yet, so
+ * that we do all validations with the same
+ * time. */
+ if (realtime == USEC_INFINITY)
+ realtime = now(CLOCK_REALTIME);
+
+ /* Yay, we found a matching RRSIG with a matching
+ * DNSKEY, awesome. Now let's verify all entries of
+ * the RRSet against the RRSIG and DNSKEY
+ * combination. */
+
+ r = dnssec_verify_rrset(a, key, rrsig, dnskey, realtime, &one_result);
+ if (r < 0)
+ return r;
+
+ switch (one_result) {
+
+ case DNSSEC_VALIDATED:
+ case DNSSEC_VALIDATED_WILDCARD:
+ /* Yay, the RR has been validated,
+ * return immediately, but fix up the expiry */
+ if (ret_rrsig)
+ *ret_rrsig = rrsig;
+
+ *result = one_result;
+ return 0;
+
+ case DNSSEC_INVALID:
+ /* If the signature is invalid, let's try another
+ key and/or signature. After all they
+ key_tags and stuff are not unique, and
+ might be shared by multiple keys. */
+ found_invalid = true;
+ continue;
+
+ case DNSSEC_UNSUPPORTED_ALGORITHM:
+ /* If the key algorithm is
+ unsupported, try another
+ RRSIG/DNSKEY pair, but remember we
+ encountered this, so that we can
+ return a proper error when we
+ encounter nothing better. */
+ found_unsupported_algorithm = true;
+ continue;
+
+ case DNSSEC_SIGNATURE_EXPIRED:
+ /* If the signature is expired, try
+ another one, but remember it, so
+ that we can return this */
+ found_expired_rrsig = true;
+ continue;
+
+ default:
+ assert_not_reached();
+ }
+ }
+ }
+
+ if (found_expired_rrsig)
+ *result = DNSSEC_SIGNATURE_EXPIRED;
+ else if (found_unsupported_algorithm)
+ *result = DNSSEC_UNSUPPORTED_ALGORITHM;
+ else if (found_invalid)
+ *result = DNSSEC_INVALID;
+ else if (found_rrsig)
+ *result = DNSSEC_MISSING_KEY;
+ else
+ *result = DNSSEC_NO_SIGNATURE;
+
+ if (ret_rrsig)
+ *ret_rrsig = NULL;
+
+ return 0;
+}
+
+int dnssec_has_rrsig(DnsAnswer *a, const DnsResourceKey *key) {
+ DnsResourceRecord *rr;
+ int r;
+
+ /* Checks whether there's at least one RRSIG in 'a' that protects RRs of the specified key */
+
+ DNS_ANSWER_FOREACH(rr, a) {
+ r = dnssec_key_match_rrsig(key, rr);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ return 1;
+ }
+
+ return 0;
+}
+
+static hash_md_t digest_to_hash_md(uint8_t algorithm) {
+
+ /* Translates a DNSSEC digest algorithm into an openssl/gcrypt digest identifier */
+
+ switch (algorithm) {
+
+ case DNSSEC_DIGEST_SHA1:
+ return OPENSSL_OR_GCRYPT(EVP_sha1(), GCRY_MD_SHA1);
+
+ case DNSSEC_DIGEST_SHA256:
+ return OPENSSL_OR_GCRYPT(EVP_sha256(), GCRY_MD_SHA256);
+
+ case DNSSEC_DIGEST_SHA384:
+ return OPENSSL_OR_GCRYPT(EVP_sha384(), GCRY_MD_SHA384);
+
+ default:
+ return OPENSSL_OR_GCRYPT(NULL, -EOPNOTSUPP);
+ }
+}
+
+int dnssec_verify_dnskey_by_ds(DnsResourceRecord *dnskey, DnsResourceRecord *ds, bool mask_revoke) {
+ uint8_t wire_format[DNS_WIRE_FORMAT_HOSTNAME_MAX];
+ int r;
+
+ assert(dnskey);
+ assert(ds);
+
+ /* Implements DNSKEY verification by a DS, according to RFC 4035, section 5.2 */
+
+ if (dnskey->key->type != DNS_TYPE_DNSKEY)
+ return -EINVAL;
+ if (ds->key->type != DNS_TYPE_DS)
+ return -EINVAL;
+ if ((dnskey->dnskey.flags & DNSKEY_FLAG_ZONE_KEY) == 0)
+ return -EKEYREJECTED;
+ if (!mask_revoke && (dnskey->dnskey.flags & DNSKEY_FLAG_REVOKE))
+ return -EKEYREJECTED;
+ if (dnskey->dnskey.protocol != 3)
+ return -EKEYREJECTED;
+
+ if (dnskey->dnskey.algorithm != ds->ds.algorithm)
+ return 0;
+ if (dnssec_keytag(dnskey, mask_revoke) != ds->ds.key_tag)
+ return 0;
+
+ r = dns_name_to_wire_format(dns_resource_key_name(dnskey->key), wire_format, sizeof wire_format, true);
+ if (r < 0)
+ return r;
+
+ hash_md_t md_algorithm = digest_to_hash_md(ds->ds.digest_type);
+
+#if PREFER_OPENSSL
+ if (!md_algorithm)
+ return -EOPNOTSUPP;
+
+ _cleanup_(EVP_MD_CTX_freep) EVP_MD_CTX *ctx = NULL;
+ uint8_t result[EVP_MAX_MD_SIZE];
+
+ unsigned hash_size = EVP_MD_size(md_algorithm);
+ assert(hash_size > 0);
+
+ if (ds->ds.digest_size != hash_size)
+ return 0;
+
+ ctx = EVP_MD_CTX_new();
+ if (!ctx)
+ return -ENOMEM;
+
+ if (EVP_DigestInit_ex(ctx, md_algorithm, NULL) <= 0)
+ return -EIO;
+
+ if (EVP_DigestUpdate(ctx, wire_format, r) <= 0)
+ return -EIO;
+
+ if (mask_revoke)
+ md_add_uint16(ctx, dnskey->dnskey.flags & ~DNSKEY_FLAG_REVOKE);
+ else
+ md_add_uint16(ctx, dnskey->dnskey.flags);
+
+ r = md_add_uint8(ctx, dnskey->dnskey.protocol);
+ if (r <= 0)
+ return r;
+ r = md_add_uint8(ctx, dnskey->dnskey.algorithm);
+ if (r <= 0)
+ return r;
+ if (EVP_DigestUpdate(ctx, dnskey->dnskey.key, dnskey->dnskey.key_size) <= 0)
+ return -EIO;
+
+ if (EVP_DigestFinal_ex(ctx, result, NULL) <= 0)
+ return -EIO;
+
+#else
+ if (md_algorithm < 0)
+ return -EOPNOTSUPP;
+
+ initialize_libgcrypt(false);
+
+ _cleanup_(gcry_md_closep) gcry_md_hd_t md = NULL;
+
+ size_t hash_size = gcry_md_get_algo_dlen(md_algorithm);
+ assert(hash_size > 0);
+
+ if (ds->ds.digest_size != hash_size)
+ return 0;
+
+ gcry_error_t err = gcry_md_open(&md, md_algorithm, 0);
+ if (gcry_err_code(err) != GPG_ERR_NO_ERROR || !md)
+ return -EIO;
+
+ gcry_md_write(md, wire_format, r);
+ if (mask_revoke)
+ md_add_uint16(md, dnskey->dnskey.flags & ~DNSKEY_FLAG_REVOKE);
+ else
+ md_add_uint16(md, dnskey->dnskey.flags);
+ md_add_uint8(md, dnskey->dnskey.protocol);
+ md_add_uint8(md, dnskey->dnskey.algorithm);
+ gcry_md_write(md, dnskey->dnskey.key, dnskey->dnskey.key_size);
+
+ void *result = gcry_md_read(md, 0);
+ if (!result)
+ return -EIO;
+#endif
+
+ return memcmp(result, ds->ds.digest, ds->ds.digest_size) == 0;
+}
+
+int dnssec_verify_dnskey_by_ds_search(DnsResourceRecord *dnskey, DnsAnswer *validated_ds) {
+ DnsResourceRecord *ds;
+ DnsAnswerFlags flags;
+ int r;
+
+ assert(dnskey);
+
+ if (dnskey->key->type != DNS_TYPE_DNSKEY)
+ return 0;
+
+ DNS_ANSWER_FOREACH_FLAGS(ds, flags, validated_ds) {
+
+ if ((flags & DNS_ANSWER_AUTHENTICATED) == 0)
+ continue;
+
+ if (ds->key->type != DNS_TYPE_DS)
+ continue;
+ if (ds->key->class != dnskey->key->class)
+ continue;
+
+ r = dns_name_equal(dns_resource_key_name(dnskey->key), dns_resource_key_name(ds->key));
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ r = dnssec_verify_dnskey_by_ds(dnskey, ds, false);
+ if (IN_SET(r, -EKEYREJECTED, -EOPNOTSUPP))
+ return 0; /* The DNSKEY is revoked or otherwise invalid, or we don't support the digest algorithm */
+ if (r < 0)
+ return r;
+ if (r > 0)
+ return 1;
+ }
+
+ return 0;
+}
+
+static hash_md_t nsec3_hash_to_hash_md(uint8_t algorithm) {
+
+ /* Translates a DNSSEC NSEC3 hash algorithm into an openssl/gcrypt digest identifier */
+
+ switch (algorithm) {
+
+ case NSEC3_ALGORITHM_SHA1:
+ return OPENSSL_OR_GCRYPT(EVP_sha1(), GCRY_MD_SHA1);
+
+ default:
+ return OPENSSL_OR_GCRYPT(NULL, -EOPNOTSUPP);
+ }
+}
+
+int dnssec_nsec3_hash(DnsResourceRecord *nsec3, const char *name, void *ret) {
+ uint8_t wire_format[DNS_WIRE_FORMAT_HOSTNAME_MAX];
+ int r;
+
+ assert(nsec3);
+ assert(name);
+ assert(ret);
+
+ if (nsec3->key->type != DNS_TYPE_NSEC3)
+ return -EINVAL;
+
+ if (nsec3->nsec3.iterations > NSEC3_ITERATIONS_MAX)
+ return log_debug_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
+ "Ignoring NSEC3 RR %s with excessive number of iterations.",
+ dns_resource_record_to_string(nsec3));
+
+ hash_md_t algorithm = nsec3_hash_to_hash_md(nsec3->nsec3.algorithm);
+#if PREFER_OPENSSL
+ if (!algorithm)
+ return -EOPNOTSUPP;
+
+ size_t hash_size = EVP_MD_size(algorithm);
+ assert(hash_size > 0);
+
+ if (nsec3->nsec3.next_hashed_name_size != hash_size)
+ return -EINVAL;
+
+ _cleanup_(EVP_MD_CTX_freep) EVP_MD_CTX *ctx = EVP_MD_CTX_new();
+ if (!ctx)
+ return -ENOMEM;
+
+ if (EVP_DigestInit_ex(ctx, algorithm, NULL) <= 0)
+ return -EIO;
+
+ r = dns_name_to_wire_format(name, wire_format, sizeof(wire_format), true);
+ if (r < 0)
+ return r;
+
+ if (EVP_DigestUpdate(ctx, wire_format, r) <= 0)
+ return -EIO;
+ if (EVP_DigestUpdate(ctx, nsec3->nsec3.salt, nsec3->nsec3.salt_size) <= 0)
+ return -EIO;
+
+ uint8_t result[EVP_MAX_MD_SIZE];
+ if (EVP_DigestFinal_ex(ctx, result, NULL) <= 0)
+ return -EIO;
+
+ for (unsigned k = 0; k < nsec3->nsec3.iterations; k++) {
+ if (EVP_DigestInit_ex(ctx, algorithm, NULL) <= 0)
+ return -EIO;
+ if (EVP_DigestUpdate(ctx, result, hash_size) <= 0)
+ return -EIO;
+ if (EVP_DigestUpdate(ctx, nsec3->nsec3.salt, nsec3->nsec3.salt_size) <= 0)
+ return -EIO;
+
+ if (EVP_DigestFinal_ex(ctx, result, NULL) <= 0)
+ return -EIO;
+ }
+#else
+ if (algorithm < 0)
+ return algorithm;
+
+ initialize_libgcrypt(false);
+
+ unsigned hash_size = gcry_md_get_algo_dlen(algorithm);
+ assert(hash_size > 0);
+
+ if (nsec3->nsec3.next_hashed_name_size != hash_size)
+ return -EINVAL;
+
+ r = dns_name_to_wire_format(name, wire_format, sizeof(wire_format), true);
+ if (r < 0)
+ return r;
+
+ _cleanup_(gcry_md_closep) gcry_md_hd_t md = NULL;
+ gcry_error_t err = gcry_md_open(&md, algorithm, 0);
+ if (gcry_err_code(err) != GPG_ERR_NO_ERROR || !md)
+ return -EIO;
+
+ gcry_md_write(md, wire_format, r);
+ gcry_md_write(md, nsec3->nsec3.salt, nsec3->nsec3.salt_size);
+
+ void *result = gcry_md_read(md, 0);
+ if (!result)
+ return -EIO;
+
+ for (unsigned k = 0; k < nsec3->nsec3.iterations; k++) {
+ uint8_t tmp[hash_size];
+ memcpy(tmp, result, hash_size);
+
+ gcry_md_reset(md);
+ gcry_md_write(md, tmp, hash_size);
+ gcry_md_write(md, nsec3->nsec3.salt, nsec3->nsec3.salt_size);
+
+ result = gcry_md_read(md, 0);
+ if (!result)
+ return -EIO;
+ }
+#endif
+
+ memcpy(ret, result, hash_size);
+ return (int) hash_size;
+}
+
+static int nsec3_is_good(DnsResourceRecord *rr, DnsResourceRecord *nsec3) {
+ const char *a, *b;
+ int r;
+
+ assert(rr);
+
+ if (rr->key->type != DNS_TYPE_NSEC3)
+ return 0;
+
+ /* RFC 5155, Section 8.2 says we MUST ignore NSEC3 RRs with flags != 0 or 1 */
+ if (!IN_SET(rr->nsec3.flags, 0, 1))
+ return 0;
+
+ /* Ignore NSEC3 RRs whose algorithm we don't know */
+#if PREFER_OPENSSL
+ if (!nsec3_hash_to_hash_md(rr->nsec3.algorithm))
+ return 0;
+#else
+ if (nsec3_hash_to_hash_md(rr->nsec3.algorithm) < 0)
+ return 0;
+#endif
+
+ /* Ignore NSEC3 RRs with an excessive number of required iterations */
+ if (rr->nsec3.iterations > NSEC3_ITERATIONS_MAX)
+ return 0;
+
+ /* Ignore NSEC3 RRs generated from wildcards. If these NSEC3 RRs weren't correctly signed we can't make this
+ * check (since rr->n_skip_labels_source is -1), but that's OK, as we won't trust them anyway in that case. */
+ if (!IN_SET(rr->n_skip_labels_source, 0, UINT8_MAX))
+ return 0;
+ /* Ignore NSEC3 RRs that are located anywhere else than one label below the zone */
+ if (!IN_SET(rr->n_skip_labels_signer, 1, UINT8_MAX))
+ return 0;
+
+ if (!nsec3)
+ return 1;
+
+ /* If a second NSEC3 RR is specified, also check if they are from the same zone. */
+
+ if (nsec3 == rr) /* Shortcut */
+ return 1;
+
+ if (rr->key->class != nsec3->key->class)
+ return 0;
+ if (rr->nsec3.algorithm != nsec3->nsec3.algorithm)
+ return 0;
+ if (rr->nsec3.iterations != nsec3->nsec3.iterations)
+ return 0;
+ if (rr->nsec3.salt_size != nsec3->nsec3.salt_size)
+ return 0;
+ if (memcmp_safe(rr->nsec3.salt, nsec3->nsec3.salt, rr->nsec3.salt_size) != 0)
+ return 0;
+
+ a = dns_resource_key_name(rr->key);
+ r = dns_name_parent(&a); /* strip off hash */
+ if (r <= 0)
+ return r;
+
+ b = dns_resource_key_name(nsec3->key);
+ r = dns_name_parent(&b); /* strip off hash */
+ if (r <= 0)
+ return r;
+
+ /* Make sure both have the same parent */
+ return dns_name_equal(a, b);
+}
+
+static int nsec3_hashed_domain_format(const uint8_t *hashed, size_t hashed_size, const char *zone, char **ret) {
+ _cleanup_free_ char *l = NULL;
+ char *j;
+
+ assert(hashed);
+ assert(hashed_size > 0);
+ assert(zone);
+ assert(ret);
+
+ l = base32hexmem(hashed, hashed_size, false);
+ if (!l)
+ return -ENOMEM;
+
+ j = strjoin(l, ".", zone);
+ if (!j)
+ return -ENOMEM;
+
+ *ret = j;
+ return (int) hashed_size;
+}
+
+static int nsec3_hashed_domain_make(DnsResourceRecord *nsec3, const char *domain, const char *zone, char **ret) {
+ uint8_t hashed[DNSSEC_HASH_SIZE_MAX];
+ int hashed_size;
+
+ assert(nsec3);
+ assert(domain);
+ assert(zone);
+ assert(ret);
+
+ hashed_size = dnssec_nsec3_hash(nsec3, domain, hashed);
+ if (hashed_size < 0)
+ return hashed_size;
+
+ return nsec3_hashed_domain_format(hashed, (size_t) hashed_size, zone, ret);
+}
+
+/* See RFC 5155, Section 8
+ * First try to find a NSEC3 record that matches our query precisely, if that fails, find the closest
+ * enclosure. Secondly, find a proof that there is no closer enclosure and either a proof that there
+ * is no wildcard domain as a direct descendant of the closest enclosure, or find an NSEC3 record that
+ * matches the wildcard domain.
+ *
+ * Based on this we can prove either the existence of the record in @key, or NXDOMAIN or NODATA, or
+ * that there is no proof either way. The latter is the case if a proof of non-existence of a given
+ * name uses an NSEC3 record with the opt-out bit set. Lastly, if we are given insufficient NSEC3 records
+ * to conclude anything we indicate this by returning NO_RR. */
+static int dnssec_test_nsec3(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated, uint32_t *ttl) {
+ _cleanup_free_ char *next_closer_domain = NULL, *wildcard_domain = NULL;
+ const char *zone, *p, *pp = NULL, *wildcard;
+ DnsResourceRecord *rr, *enclosure_rr, *zone_rr, *wildcard_rr = NULL;
+ DnsAnswerFlags flags;
+ int hashed_size, r;
+ bool a, no_closer = false, no_wildcard = false, optout = false;
+
+ assert(key);
+ assert(result);
+
+ /* First step, find the zone name and the NSEC3 parameters of the zone.
+ * it is sufficient to look for the longest common suffix we find with
+ * any NSEC3 RR in the response. Any NSEC3 record will do as all NSEC3
+ * records from a given zone in a response must use the same
+ * parameters. */
+ zone = dns_resource_key_name(key);
+ for (;;) {
+ DNS_ANSWER_FOREACH_FLAGS(zone_rr, flags, answer) {
+ r = nsec3_is_good(zone_rr, NULL);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ r = dns_name_equal_skip(dns_resource_key_name(zone_rr->key), 1, zone);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ goto found_zone;
+ }
+
+ /* Strip one label from the front */
+ r = dns_name_parent(&zone);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ break;
+ }
+
+ *result = DNSSEC_NSEC_NO_RR;
+ return 0;
+
+found_zone:
+ /* Second step, find the closest encloser NSEC3 RR in 'answer' that matches 'key' */
+ p = dns_resource_key_name(key);
+ for (;;) {
+ _cleanup_free_ char *hashed_domain = NULL;
+
+ hashed_size = nsec3_hashed_domain_make(zone_rr, p, zone, &hashed_domain);
+ if (hashed_size == -EOPNOTSUPP) {
+ *result = DNSSEC_NSEC_UNSUPPORTED_ALGORITHM;
+ return 0;
+ }
+ if (hashed_size < 0)
+ return hashed_size;
+
+ DNS_ANSWER_FOREACH_FLAGS(enclosure_rr, flags, answer) {
+
+ r = nsec3_is_good(enclosure_rr, zone_rr);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ if (enclosure_rr->nsec3.next_hashed_name_size != (size_t) hashed_size)
+ continue;
+
+ r = dns_name_equal(dns_resource_key_name(enclosure_rr->key), hashed_domain);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ a = flags & DNS_ANSWER_AUTHENTICATED;
+ goto found_closest_encloser;
+ }
+ }
+
+ /* We didn't find the closest encloser with this name,
+ * but let's remember this domain name, it might be
+ * the next closer name */
+
+ pp = p;
+
+ /* Strip one label from the front */
+ r = dns_name_parent(&p);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ break;
+ }
+
+ *result = DNSSEC_NSEC_NO_RR;
+ return 0;
+
+found_closest_encloser:
+ /* We found a closest encloser in 'p'; next closer is 'pp' */
+
+ if (!pp) {
+ /* We have an exact match! If we area looking for a DS RR, then we must insist that we got the NSEC3 RR
+ * from the parent. Otherwise the one from the child. Do so, by checking whether SOA and NS are
+ * appropriately set. */
+
+ if (key->type == DNS_TYPE_DS) {
+ if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_SOA))
+ return -EBADMSG;
+ } else {
+ if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_NS) &&
+ !bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_SOA))
+ return -EBADMSG;
+ }
+
+ /* No next closer NSEC3 RR. That means there's a direct NSEC3 RR for our key. */
+ if (bitmap_isset(enclosure_rr->nsec3.types, key->type))
+ *result = DNSSEC_NSEC_FOUND;
+ else if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_CNAME))
+ *result = DNSSEC_NSEC_CNAME;
+ else
+ *result = DNSSEC_NSEC_NODATA;
+
+ if (authenticated)
+ *authenticated = a;
+ if (ttl)
+ *ttl = enclosure_rr->ttl;
+
+ return 0;
+ }
+
+ /* Ensure this is not a DNAME domain, see RFC5155, section 8.3. */
+ if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_DNAME))
+ return -EBADMSG;
+
+ /* Ensure that this data is from the delegated domain
+ * (i.e. originates from the "lower" DNS server), and isn't
+ * just glue records (i.e. doesn't originate from the "upper"
+ * DNS server). */
+ if (bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_NS) &&
+ !bitmap_isset(enclosure_rr->nsec3.types, DNS_TYPE_SOA))
+ return -EBADMSG;
+
+ /* Prove that there is no next closer and whether or not there is a wildcard domain. */
+
+ wildcard = strjoina("*.", p);
+ r = nsec3_hashed_domain_make(enclosure_rr, wildcard, zone, &wildcard_domain);
+ if (r < 0)
+ return r;
+ if (r != hashed_size)
+ return -EBADMSG;
+
+ r = nsec3_hashed_domain_make(enclosure_rr, pp, zone, &next_closer_domain);
+ if (r < 0)
+ return r;
+ if (r != hashed_size)
+ return -EBADMSG;
+
+ DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
+ _cleanup_free_ char *next_hashed_domain = NULL;
+
+ r = nsec3_is_good(rr, zone_rr);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ r = nsec3_hashed_domain_format(rr->nsec3.next_hashed_name, rr->nsec3.next_hashed_name_size, zone, &next_hashed_domain);
+ if (r < 0)
+ return r;
+
+ r = dns_name_between(dns_resource_key_name(rr->key), next_closer_domain, next_hashed_domain);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ if (rr->nsec3.flags & 1)
+ optout = true;
+
+ a = a && (flags & DNS_ANSWER_AUTHENTICATED);
+
+ no_closer = true;
+ }
+
+ r = dns_name_equal(dns_resource_key_name(rr->key), wildcard_domain);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ a = a && (flags & DNS_ANSWER_AUTHENTICATED);
+
+ wildcard_rr = rr;
+ }
+
+ r = dns_name_between(dns_resource_key_name(rr->key), wildcard_domain, next_hashed_domain);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ if (rr->nsec3.flags & 1)
+ /* This only makes sense if we have a wildcard delegation, which is
+ * very unlikely, see RFC 4592, Section 4.2, but we cannot rely on
+ * this not happening, so hence cannot simply conclude NXDOMAIN as
+ * we would wish */
+ optout = true;
+
+ a = a && (flags & DNS_ANSWER_AUTHENTICATED);
+
+ no_wildcard = true;
+ }
+ }
+
+ if (wildcard_rr && no_wildcard)
+ return -EBADMSG;
+
+ if (!no_closer) {
+ *result = DNSSEC_NSEC_NO_RR;
+ return 0;
+ }
+
+ if (wildcard_rr) {
+ /* A wildcard exists that matches our query. */
+ if (optout)
+ /* This is not specified in any RFC to the best of my knowledge, but
+ * if the next closer enclosure is covered by an opt-out NSEC3 RR
+ * it means that we cannot prove that the source of synthesis is
+ * correct, as there may be a closer match. */
+ *result = DNSSEC_NSEC_OPTOUT;
+ else if (bitmap_isset(wildcard_rr->nsec3.types, key->type))
+ *result = DNSSEC_NSEC_FOUND;
+ else if (bitmap_isset(wildcard_rr->nsec3.types, DNS_TYPE_CNAME))
+ *result = DNSSEC_NSEC_CNAME;
+ else
+ *result = DNSSEC_NSEC_NODATA;
+ } else {
+ if (optout)
+ /* The RFC only specifies that we have to care for optout for NODATA for
+ * DS records. However, children of an insecure opt-out delegation should
+ * also be considered opt-out, rather than verified NXDOMAIN.
+ * Note that we do not require a proof of wildcard non-existence if the
+ * next closer domain is covered by an opt-out, as that would not provide
+ * any additional information. */
+ *result = DNSSEC_NSEC_OPTOUT;
+ else if (no_wildcard)
+ *result = DNSSEC_NSEC_NXDOMAIN;
+ else {
+ *result = DNSSEC_NSEC_NO_RR;
+
+ return 0;
+ }
+ }
+
+ if (authenticated)
+ *authenticated = a;
+
+ if (ttl)
+ *ttl = enclosure_rr->ttl;
+
+ return 0;
+}
+
+static int dnssec_nsec_wildcard_equal(DnsResourceRecord *rr, const char *name) {
+ char label[DNS_LABEL_MAX];
+ const char *n;
+ int r;
+
+ assert(rr);
+ assert(rr->key->type == DNS_TYPE_NSEC);
+
+ /* Checks whether the specified RR has a name beginning in "*.", and if the rest is a suffix of our name */
+
+ if (rr->n_skip_labels_source != 1)
+ return 0;
+
+ n = dns_resource_key_name(rr->key);
+ r = dns_label_unescape(&n, label, sizeof label, 0);
+ if (r <= 0)
+ return r;
+ if (r != 1 || label[0] != '*')
+ return 0;
+
+ return dns_name_endswith(name, n);
+}
+
+static int dnssec_nsec_in_path(DnsResourceRecord *rr, const char *name) {
+ const char *nn, *common_suffix;
+ int r;
+
+ assert(rr);
+ assert(rr->key->type == DNS_TYPE_NSEC);
+
+ /* Checks whether the specified nsec RR indicates that name is an empty non-terminal (ENT)
+ *
+ * A couple of examples:
+ *
+ * NSEC bar → waldo.foo.bar: indicates that foo.bar exists and is an ENT
+ * NSEC waldo.foo.bar → yyy.zzz.xoo.bar: indicates that xoo.bar and zzz.xoo.bar exist and are ENTs
+ * NSEC yyy.zzz.xoo.bar → bar: indicates pretty much nothing about ENTs
+ */
+
+ /* First, determine parent of next domain. */
+ nn = rr->nsec.next_domain_name;
+ r = dns_name_parent(&nn);
+ if (r <= 0)
+ return r;
+
+ /* If the name we just determined is not equal or child of the name we are interested in, then we can't say
+ * anything at all. */
+ r = dns_name_endswith(nn, name);
+ if (r <= 0)
+ return r;
+
+ /* If the name we are interested in is not a prefix of the common suffix of the NSEC RR's owner and next domain names, then we can't say anything either. */
+ r = dns_name_common_suffix(dns_resource_key_name(rr->key), rr->nsec.next_domain_name, &common_suffix);
+ if (r < 0)
+ return r;
+
+ return dns_name_endswith(name, common_suffix);
+}
+
+static int dnssec_nsec_from_parent_zone(DnsResourceRecord *rr, const char *name) {
+ int r;
+
+ assert(rr);
+ assert(rr->key->type == DNS_TYPE_NSEC);
+
+ /* Checks whether this NSEC originates to the parent zone or the child zone. */
+
+ r = dns_name_parent(&name);
+ if (r <= 0)
+ return r;
+
+ r = dns_name_equal(name, dns_resource_key_name(rr->key));
+ if (r <= 0)
+ return r;
+
+ /* DNAME, and NS without SOA is an indication for a delegation. */
+ if (bitmap_isset(rr->nsec.types, DNS_TYPE_DNAME))
+ return 1;
+
+ if (bitmap_isset(rr->nsec.types, DNS_TYPE_NS) && !bitmap_isset(rr->nsec.types, DNS_TYPE_SOA))
+ return 1;
+
+ return 0;
+}
+
+static int dnssec_nsec_covers(DnsResourceRecord *rr, const char *name) {
+ const char *signer;
+ int r;
+
+ assert(rr);
+ assert(rr->key->type == DNS_TYPE_NSEC);
+
+ /* Checks whether the name is covered by this NSEC RR. This means, that the name is somewhere below the NSEC's
+ * signer name, and between the NSEC's two names. */
+
+ r = dns_resource_record_signer(rr, &signer);
+ if (r < 0)
+ return r;
+
+ r = dns_name_endswith(name, signer); /* this NSEC isn't suitable the name is not in the signer's domain */
+ if (r <= 0)
+ return r;
+
+ return dns_name_between(dns_resource_key_name(rr->key), name, rr->nsec.next_domain_name);
+}
+
+static int dnssec_nsec_generate_wildcard(DnsResourceRecord *rr, const char *name, char **wc) {
+ const char *common_suffix1, *common_suffix2, *signer;
+ int r, labels1, labels2;
+
+ assert(rr);
+ assert(rr->key->type == DNS_TYPE_NSEC);
+
+ /* Generates "Wildcard at the Closest Encloser" for the given name and NSEC RR. */
+
+ r = dns_resource_record_signer(rr, &signer);
+ if (r < 0)
+ return r;
+
+ r = dns_name_endswith(name, signer); /* this NSEC isn't suitable the name is not in the signer's domain */
+ if (r <= 0)
+ return r;
+
+ r = dns_name_common_suffix(name, dns_resource_key_name(rr->key), &common_suffix1);
+ if (r < 0)
+ return r;
+
+ r = dns_name_common_suffix(name, rr->nsec.next_domain_name, &common_suffix2);
+ if (r < 0)
+ return r;
+
+ labels1 = dns_name_count_labels(common_suffix1);
+ if (labels1 < 0)
+ return labels1;
+
+ labels2 = dns_name_count_labels(common_suffix2);
+ if (labels2 < 0)
+ return labels2;
+
+ if (labels1 > labels2)
+ r = dns_name_concat("*", common_suffix1, 0, wc);
+ else
+ r = dns_name_concat("*", common_suffix2, 0, wc);
+
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+int dnssec_nsec_test(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated, uint32_t *ttl) {
+ bool have_nsec3 = false, covering_rr_authenticated = false, wildcard_rr_authenticated = false;
+ DnsResourceRecord *rr, *covering_rr = NULL, *wildcard_rr = NULL;
+ DnsAnswerFlags flags;
+ const char *name;
+ int r;
+
+ assert(key);
+ assert(result);
+
+ /* Look for any NSEC/NSEC3 RRs that say something about the specified key. */
+
+ name = dns_resource_key_name(key);
+
+ DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
+
+ if (rr->key->class != key->class)
+ continue;
+
+ have_nsec3 = have_nsec3 || (rr->key->type == DNS_TYPE_NSEC3);
+
+ if (rr->key->type != DNS_TYPE_NSEC)
+ continue;
+
+ /* The following checks only make sense for NSEC RRs that are not expanded from a wildcard */
+ r = dns_resource_record_is_synthetic(rr);
+ if (r == -ENODATA) /* No signing RR known. */
+ continue;
+ if (r < 0)
+ return r;
+ if (r > 0)
+ continue;
+
+ /* Check if this is a direct match. If so, we have encountered a NODATA case */
+ r = dns_name_equal(dns_resource_key_name(rr->key), name);
+ if (r < 0)
+ return r;
+ if (r == 0) {
+ /* If it's not a direct match, maybe it's a wild card match? */
+ r = dnssec_nsec_wildcard_equal(rr, name);
+ if (r < 0)
+ return r;
+ }
+ if (r > 0) {
+ if (key->type == DNS_TYPE_DS) {
+ /* If we look for a DS RR and the server sent us the NSEC RR of the child zone
+ * we have a problem. For DS RRs we want the NSEC RR from the parent */
+ if (bitmap_isset(rr->nsec.types, DNS_TYPE_SOA))
+ continue;
+ } else {
+ /* For all RR types, ensure that if NS is set SOA is set too, so that we know
+ * we got the child's NSEC. */
+ if (bitmap_isset(rr->nsec.types, DNS_TYPE_NS) &&
+ !bitmap_isset(rr->nsec.types, DNS_TYPE_SOA))
+ continue;
+ }
+
+ if (bitmap_isset(rr->nsec.types, key->type))
+ *result = DNSSEC_NSEC_FOUND;
+ else if (bitmap_isset(rr->nsec.types, DNS_TYPE_CNAME))
+ *result = DNSSEC_NSEC_CNAME;
+ else
+ *result = DNSSEC_NSEC_NODATA;
+
+ if (authenticated)
+ *authenticated = flags & DNS_ANSWER_AUTHENTICATED;
+ if (ttl)
+ *ttl = rr->ttl;
+
+ return 0;
+ }
+
+ /* Check if the name we are looking for is an empty non-terminal within the owner or next name
+ * of the NSEC RR. */
+ r = dnssec_nsec_in_path(rr, name);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ *result = DNSSEC_NSEC_NODATA;
+
+ if (authenticated)
+ *authenticated = flags & DNS_ANSWER_AUTHENTICATED;
+ if (ttl)
+ *ttl = rr->ttl;
+
+ return 0;
+ }
+
+ /* The following two "covering" checks, are not useful if the NSEC is from the parent */
+ r = dnssec_nsec_from_parent_zone(rr, name);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ continue;
+
+ /* Check if this NSEC RR proves the absence of an explicit RR under this name */
+ r = dnssec_nsec_covers(rr, name);
+ if (r < 0)
+ return r;
+ if (r > 0 && (!covering_rr || !covering_rr_authenticated)) {
+ covering_rr = rr;
+ covering_rr_authenticated = flags & DNS_ANSWER_AUTHENTICATED;
+ }
+ }
+
+ if (covering_rr) {
+ _cleanup_free_ char *wc = NULL;
+ r = dnssec_nsec_generate_wildcard(covering_rr, name, &wc);
+ if (r < 0)
+ return r;
+
+ DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
+
+ if (rr->key->class != key->class)
+ continue;
+
+ if (rr->key->type != DNS_TYPE_NSEC)
+ continue;
+
+ /* Check if this NSEC RR proves the nonexistence of the wildcard */
+ r = dnssec_nsec_covers(rr, wc);
+ if (r < 0)
+ return r;
+ if (r > 0 && (!wildcard_rr || !wildcard_rr_authenticated)) {
+ wildcard_rr = rr;
+ wildcard_rr_authenticated = flags & DNS_ANSWER_AUTHENTICATED;
+ }
+ }
+ }
+
+ if (covering_rr && wildcard_rr) {
+ /* If we could prove that neither the name itself, nor the wildcard at the closest encloser exists, we
+ * proved the NXDOMAIN case. */
+ *result = DNSSEC_NSEC_NXDOMAIN;
+
+ if (authenticated)
+ *authenticated = covering_rr_authenticated && wildcard_rr_authenticated;
+ if (ttl)
+ *ttl = MIN(covering_rr->ttl, wildcard_rr->ttl);
+
+ return 0;
+ }
+
+ /* OK, this was not sufficient. Let's see if NSEC3 can help. */
+ if (have_nsec3)
+ return dnssec_test_nsec3(answer, key, result, authenticated, ttl);
+
+ /* No appropriate NSEC RR found, report this. */
+ *result = DNSSEC_NSEC_NO_RR;
+ return 0;
+}
+
+static int dnssec_nsec_test_enclosed(DnsAnswer *answer, uint16_t type, const char *name, const char *zone, bool *authenticated) {
+ DnsResourceRecord *rr;
+ DnsAnswerFlags flags;
+ int r;
+
+ assert(name);
+ assert(zone);
+
+ /* Checks whether there's an NSEC/NSEC3 that proves that the specified 'name' is non-existing in the specified
+ * 'zone'. The 'zone' must be a suffix of the 'name'. */
+
+ DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
+ bool found = false;
+
+ if (rr->key->type != type && type != DNS_TYPE_ANY)
+ continue;
+
+ switch (rr->key->type) {
+
+ case DNS_TYPE_NSEC:
+
+ /* We only care for NSEC RRs from the indicated zone */
+ r = dns_resource_record_is_signer(rr, zone);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ r = dns_name_between(dns_resource_key_name(rr->key), name, rr->nsec.next_domain_name);
+ if (r < 0)
+ return r;
+
+ found = r > 0;
+ break;
+
+ case DNS_TYPE_NSEC3: {
+ _cleanup_free_ char *hashed_domain = NULL, *next_hashed_domain = NULL;
+
+ /* We only care for NSEC3 RRs from the indicated zone */
+ r = dns_resource_record_is_signer(rr, zone);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ r = nsec3_is_good(rr, NULL);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ break;
+
+ /* Format the domain we are testing with the NSEC3 RR's hash function */
+ r = nsec3_hashed_domain_make(
+ rr,
+ name,
+ zone,
+ &hashed_domain);
+ if (r < 0)
+ return r;
+ if ((size_t) r != rr->nsec3.next_hashed_name_size)
+ break;
+
+ /* Format the NSEC3's next hashed name as proper domain name */
+ r = nsec3_hashed_domain_format(
+ rr->nsec3.next_hashed_name,
+ rr->nsec3.next_hashed_name_size,
+ zone,
+ &next_hashed_domain);
+ if (r < 0)
+ return r;
+
+ r = dns_name_between(dns_resource_key_name(rr->key), hashed_domain, next_hashed_domain);
+ if (r < 0)
+ return r;
+
+ found = r > 0;
+ break;
+ }
+
+ default:
+ continue;
+ }
+
+ if (found) {
+ if (authenticated)
+ *authenticated = flags & DNS_ANSWER_AUTHENTICATED;
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+static int dnssec_test_positive_wildcard_nsec3(
+ DnsAnswer *answer,
+ const char *name,
+ const char *source,
+ const char *zone,
+ bool *authenticated) {
+
+ const char *next_closer = NULL;
+ int r;
+
+ /* Run a positive NSEC3 wildcard proof. Specifically:
+ *
+ * A proof that the "next closer" of the generating wildcard does not exist.
+ *
+ * Note a key difference between the NSEC3 and NSEC versions of the proof. NSEC RRs don't have to exist for
+ * empty non-transients. NSEC3 RRs however have to. This means it's sufficient to check if the next closer name
+ * exists for the NSEC3 RR and we are done.
+ *
+ * To prove that a.b.c.d.e.f is rightfully synthesized from a wildcard *.d.e.f all we have to check is that
+ * c.d.e.f does not exist. */
+
+ for (;;) {
+ next_closer = name;
+ r = dns_name_parent(&name);
+ if (r <= 0)
+ return r;
+
+ r = dns_name_equal(name, source);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ break;
+ }
+
+ return dnssec_nsec_test_enclosed(answer, DNS_TYPE_NSEC3, next_closer, zone, authenticated);
+}
+
+static int dnssec_test_positive_wildcard_nsec(
+ DnsAnswer *answer,
+ const char *name,
+ const char *source,
+ const char *zone,
+ bool *_authenticated) {
+
+ bool authenticated = true;
+ int r;
+
+ /* Run a positive NSEC wildcard proof. Specifically:
+ *
+ * A proof that there's neither a wildcard name nor a non-wildcard name that is a suffix of the name "name" and
+ * a prefix of the synthesizing source "source" in the zone "zone".
+ *
+ * See RFC 5155, Section 8.8 and RFC 4035, Section 5.3.4
+ *
+ * Note that if we want to prove that a.b.c.d.e.f is rightfully synthesized from a wildcard *.d.e.f, then we
+ * have to prove that none of the following exist:
+ *
+ * 1) a.b.c.d.e.f
+ * 2) *.b.c.d.e.f
+ * 3) b.c.d.e.f
+ * 4) *.c.d.e.f
+ * 5) c.d.e.f
+ */
+
+ for (;;) {
+ _cleanup_free_ char *wc = NULL;
+ bool a = false;
+
+ /* Check if there's an NSEC or NSEC3 RR that proves that the mame we determined is really non-existing,
+ * i.e between the owner name and the next name of an NSEC RR. */
+ r = dnssec_nsec_test_enclosed(answer, DNS_TYPE_NSEC, name, zone, &a);
+ if (r <= 0)
+ return r;
+
+ authenticated = authenticated && a;
+
+ /* Strip one label off */
+ r = dns_name_parent(&name);
+ if (r <= 0)
+ return r;
+
+ /* Did we reach the source of synthesis? */
+ r = dns_name_equal(name, source);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ /* Successful exit */
+ *_authenticated = authenticated;
+ return 1;
+ }
+
+ /* Safety check, that the source of synthesis is still our suffix */
+ r = dns_name_endswith(name, source);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return -EBADMSG;
+
+ /* Replace the label we stripped off with an asterisk */
+ wc = strjoin("*.", name);
+ if (!wc)
+ return -ENOMEM;
+
+ /* And check if the proof holds for the asterisk name, too */
+ r = dnssec_nsec_test_enclosed(answer, DNS_TYPE_NSEC, wc, zone, &a);
+ if (r <= 0)
+ return r;
+
+ authenticated = authenticated && a;
+ /* In the next iteration we'll check the non-asterisk-prefixed version */
+ }
+}
+
+int dnssec_test_positive_wildcard(
+ DnsAnswer *answer,
+ const char *name,
+ const char *source,
+ const char *zone,
+ bool *authenticated) {
+
+ int r;
+
+ assert(name);
+ assert(source);
+ assert(zone);
+ assert(authenticated);
+
+ r = dns_answer_contains_zone_nsec3(answer, zone);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ return dnssec_test_positive_wildcard_nsec3(answer, name, source, zone, authenticated);
+ else
+ return dnssec_test_positive_wildcard_nsec(answer, name, source, zone, authenticated);
+}
+
+#else
+
+int dnssec_verify_rrset(
+ DnsAnswer *a,
+ const DnsResourceKey *key,
+ DnsResourceRecord *rrsig,
+ DnsResourceRecord *dnskey,
+ usec_t realtime,
+ DnssecResult *result) {
+
+ return -EOPNOTSUPP;
+}
+
+int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey, bool revoked_ok) {
+
+ return -EOPNOTSUPP;
+}
+
+int dnssec_key_match_rrsig(const DnsResourceKey *key, DnsResourceRecord *rrsig) {
+
+ return -EOPNOTSUPP;
+}
+
+int dnssec_verify_rrset_search(
+ DnsAnswer *a,
+ const DnsResourceKey *key,
+ DnsAnswer *validated_dnskeys,
+ usec_t realtime,
+ DnssecResult *result,
+ DnsResourceRecord **ret_rrsig) {
+
+ return -EOPNOTSUPP;
+}
+
+int dnssec_has_rrsig(DnsAnswer *a, const DnsResourceKey *key) {
+
+ return -EOPNOTSUPP;
+}
+
+int dnssec_verify_dnskey_by_ds(DnsResourceRecord *dnskey, DnsResourceRecord *ds, bool mask_revoke) {
+
+ return -EOPNOTSUPP;
+}
+
+int dnssec_verify_dnskey_by_ds_search(DnsResourceRecord *dnskey, DnsAnswer *validated_ds) {
+
+ return -EOPNOTSUPP;
+}
+
+int dnssec_nsec3_hash(DnsResourceRecord *nsec3, const char *name, void *ret) {
+
+ return -EOPNOTSUPP;
+}
+
+int dnssec_nsec_test(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated, uint32_t *ttl) {
+
+ return -EOPNOTSUPP;
+}
+
+int dnssec_test_positive_wildcard(
+ DnsAnswer *answer,
+ const char *name,
+ const char *source,
+ const char *zone,
+ bool *authenticated) {
+
+ return -EOPNOTSUPP;
+}
+
+#endif
+
+static const char* const dnssec_result_table[_DNSSEC_RESULT_MAX] = {
+ [DNSSEC_VALIDATED] = "validated",
+ [DNSSEC_VALIDATED_WILDCARD] = "validated-wildcard",
+ [DNSSEC_INVALID] = "invalid",
+ [DNSSEC_SIGNATURE_EXPIRED] = "signature-expired",
+ [DNSSEC_UNSUPPORTED_ALGORITHM] = "unsupported-algorithm",
+ [DNSSEC_NO_SIGNATURE] = "no-signature",
+ [DNSSEC_MISSING_KEY] = "missing-key",
+ [DNSSEC_UNSIGNED] = "unsigned",
+ [DNSSEC_FAILED_AUXILIARY] = "failed-auxiliary",
+ [DNSSEC_NSEC_MISMATCH] = "nsec-mismatch",
+ [DNSSEC_INCOMPATIBLE_SERVER] = "incompatible-server",
+};
+DEFINE_STRING_TABLE_LOOKUP(dnssec_result, DnssecResult);
+
+static const char* const dnssec_verdict_table[_DNSSEC_VERDICT_MAX] = {
+ [DNSSEC_SECURE] = "secure",
+ [DNSSEC_INSECURE] = "insecure",
+ [DNSSEC_BOGUS] = "bogus",
+ [DNSSEC_INDETERMINATE] = "indeterminate",
+};
+DEFINE_STRING_TABLE_LOOKUP(dnssec_verdict, DnssecVerdict);