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Diffstat (limited to 'src/resolve/resolved-dns-dnssec.c')
-rw-r--r--src/resolve/resolved-dns-dnssec.c1682
1 files changed, 1507 insertions, 175 deletions
diff --git a/src/resolve/resolved-dns-dnssec.c b/src/resolve/resolved-dns-dnssec.c
index 792c9d8692..1f48f588ce 100644
--- a/src/resolve/resolved-dns-dnssec.c
+++ b/src/resolve/resolved-dns-dnssec.c
@@ -23,6 +23,7 @@
#include "alloc-util.h"
#include "dns-domain.h"
+#include "hexdecoct.h"
#include "resolved-dns-dnssec.h"
#include "resolved-dns-packet.h"
#include "string-table.h"
@@ -34,17 +35,12 @@
*
* TODO:
*
- * - Iterative validation
- * - NSEC proof of non-existance
- * - NSEC3 proof of non-existance
- * - Make trust anchor store read additional DS+DNSKEY data from disk
- * - wildcard zones compatibility
- * - multi-label zone compatibility
- * - DNSSEC cname/dname compatibility
- * - per-interface DNSSEC setting
- * - DSA support
- * - EC support?
- *
+ * - bus calls to override DNSEC setting per interface
+ * - log all DNSSEC downgrades
+ * - log all RRs that failed validation
+ * - enable by default
+ * - Allow clients to request DNSSEC even if DNSSEC is off
+ * - make sure when getting an NXDOMAIN response through CNAME, we still process the first CNAMEs in the packet
* */
#define VERIFY_RRS_MAX 256
@@ -53,6 +49,9 @@
/* 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:
*
@@ -64,23 +63,22 @@
* Normal RR → RRSIG/DNSKEY+ → DS → RRSIG/DNSKEY+ → DS → ... → DS → RRSIG/DNSKEY+ → DS
*/
-static bool dnssec_algorithm_supported(int algorithm) {
- return IN_SET(algorithm,
- DNSSEC_ALGORITHM_RSASHA1,
- DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1,
- DNSSEC_ALGORITHM_RSASHA256,
- DNSSEC_ALGORITHM_RSASHA512);
-}
+static void initialize_libgcrypt(void) {
+ const char *p;
+
+ if (gcry_control(GCRYCTL_INITIALIZATION_FINISHED_P))
+ return;
-static bool dnssec_digest_supported(int digest) {
- return IN_SET(digest,
- DNSSEC_DIGEST_SHA1,
- DNSSEC_DIGEST_SHA256);
+ p = gcry_check_version("1.4.5");
+ assert(p);
+
+ gcry_control(GCRYCTL_DISABLE_SECMEM);
+ gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0);
}
-uint16_t dnssec_keytag(DnsResourceRecord *dnskey) {
+uint16_t dnssec_keytag(DnsResourceRecord *dnskey, bool mask_revoke) {
const uint8_t *p;
- uint32_t sum;
+ uint32_t sum, f;
size_t i;
/* The algorithm from RFC 4034, Appendix B. */
@@ -88,8 +86,12 @@ uint16_t dnssec_keytag(DnsResourceRecord *dnskey) {
assert(dnskey);
assert(dnskey->key->type == DNS_TYPE_DNSKEY);
- sum = (uint32_t) dnskey->dnskey.flags +
- ((((uint32_t) dnskey->dnskey.protocol) << 8) + (uint32_t) dnskey->dnskey.algorithm);
+ 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;
@@ -115,21 +117,21 @@ static int rr_compare(const void *a, const void *b) {
assert(*y);
assert((*y)->wire_format);
- m = MIN((*x)->wire_format_size, (*y)->wire_format_size);
+ m = MIN(DNS_RESOURCE_RECORD_RDATA_SIZE(*x), DNS_RESOURCE_RECORD_RDATA_SIZE(*y));
- r = memcmp((*x)->wire_format, (*y)->wire_format, m);
+ r = memcmp(DNS_RESOURCE_RECORD_RDATA(*x), DNS_RESOURCE_RECORD_RDATA(*y), m);
if (r != 0)
return r;
- if ((*x)->wire_format_size < (*y)->wire_format_size)
+ if (DNS_RESOURCE_RECORD_RDATA_SIZE(*x) < DNS_RESOURCE_RECORD_RDATA_SIZE(*y))
return -1;
- else if ((*x)->wire_format_size > (*y)->wire_format_size)
+ else if (DNS_RESOURCE_RECORD_RDATA_SIZE(*x) > DNS_RESOURCE_RECORD_RDATA_SIZE(*y))
return 1;
return 0;
}
-static int dnssec_rsa_verify(
+static int dnssec_rsa_verify_raw(
const char *hash_algorithm,
const void *signature, size_t signature_size,
const void *data, size_t data_size,
@@ -219,6 +221,196 @@ finish:
return r;
}
+static int dnssec_rsa_verify(
+ const char *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(
+ const char *hash_algorithm,
+ const char *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) {
+
+ 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;
+ int k;
+
+ 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);
+
+ return k;
+}
+
+static int dnssec_ecdsa_verify(
+ const char *hash_algorithm,
+ int algorithm,
+ const void *hash, size_t hash_size,
+ DnsResourceRecord *rrsig,
+ DnsResourceRecord *dnskey) {
+
+ const char *curve;
+ size_t key_size;
+ uint8_t *q;
+
+ assert(hash);
+ assert(hash_size);
+ assert(rrsig);
+ assert(dnskey);
+
+ if (algorithm == DNSSEC_ALGORITHM_ECDSAP256SHA256) {
+ key_size = 32;
+ curve = "NIST P-256";
+ } else if (algorithm == DNSSEC_ALGORITHM_ECDSAP384SHA384) {
+ key_size = 48;
+ curve = "NIST P-384";
+ } else
+ return -EOPNOTSUPP;
+
+ if (dnskey->dnskey.key_size != key_size * 2)
+ return -EINVAL;
+
+ if (rrsig->rrsig.signature_size != key_size * 2)
+ return -EINVAL;
+
+ q = alloca(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 void md_add_uint8(gcry_md_hd_t md, uint8_t v) {
gcry_md_write(md, &v, sizeof(v));
}
@@ -233,6 +425,57 @@ static void md_add_uint32(gcry_md_hd_t md, uint32_t v) {
gcry_md_write(md, &v, sizeof(v));
}
+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 != (unsigned) -1)
+ 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;
+
+ 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;
@@ -245,8 +488,9 @@ static int dnssec_rrsig_expired(DnsResourceRecord *rrsig, usec_t 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 -EKEYREJECTED;
+ return true;
/* Permit a certain amount of clock skew of 10% of the valid
* time range. This takes inspiration from unbound's
@@ -268,21 +512,85 @@ static int dnssec_rrsig_expired(DnsResourceRecord *rrsig, usec_t realtime) {
return realtime < inception || realtime > expiration;
}
+static int algorithm_to_gcrypt_md(uint8_t algorithm) {
+
+ /* Translates a DNSSEC signature algorithm into a 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 GCRY_MD_SHA1;
+
+ case DNSSEC_ALGORITHM_RSASHA256:
+ case DNSSEC_ALGORITHM_ECDSAP256SHA256:
+ return GCRY_MD_SHA256;
+
+ case DNSSEC_ALGORITHM_ECDSAP384SHA384:
+ return GCRY_MD_SHA384;
+
+ case DNSSEC_ALGORITHM_RSASHA512:
+ return GCRY_MD_SHA512;
+
+ default:
+ return -EOPNOTSUPP;
+ }
+}
+
+static void dnssec_fix_rrset_ttl(
+ DnsResourceRecord *list[],
+ unsigned n,
+ DnsResourceRecord *rrsig,
+ usec_t realtime) {
+
+ unsigned k;
+
+ assert(list);
+ assert(n > 0);
+ assert(rrsig);
+
+ for (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;
+}
+
int dnssec_verify_rrset(
DnsAnswer *a,
- DnsResourceKey *key,
+ const DnsResourceKey *key,
DnsResourceRecord *rrsig,
DnsResourceRecord *dnskey,
usec_t realtime,
DnssecResult *result) {
uint8_t wire_format_name[DNS_WIRE_FOMAT_HOSTNAME_MAX];
- size_t exponent_size, modulus_size, hash_size;
- void *exponent, *modulus, *hash;
DnsResourceRecord **list, *rr;
+ const char *source, *name;
gcry_md_hd_t md = NULL;
+ int r, md_algorithm;
size_t k, n = 0;
- int r;
+ size_t hash_size;
+ void *hash;
+ bool wildcard;
assert(key);
assert(rrsig);
@@ -295,13 +603,21 @@ int dnssec_verify_rrset(
* using the signature "rrsig" and the key "dnskey". It's
* assumed the RRSIG and DNSKEY match. */
- if (!dnssec_algorithm_supported(rrsig->rrsig.algorithm)) {
+ md_algorithm = algorithm_to_gcrypt_md(rrsig->rrsig.algorithm);
+ if (md_algorithm == -EOPNOTSUPP) {
*result = DNSSEC_UNSUPPORTED_ALGORITHM;
return 0;
}
+ if (md_algorithm < 0)
+ return md_algorithm;
- if (a->n_rrs > VERIFY_RRS_MAX)
- return -E2BIG;
+ 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)
@@ -311,8 +627,54 @@ int dnssec_verify_rrset(
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 *, a->n_rrs);
+ list = newa(DnsResourceRecord *, dns_answer_size(a));
DNS_ANSWER_FOREACH(rr, a) {
r = dns_resource_key_equal(key, rr->key);
@@ -327,6 +689,9 @@ int dnssec_verify_rrset(
return r;
list[n++] = rr;
+
+ if (n > VERIFY_RRS_MAX)
+ return -E2BIG;
}
if (n <= 0)
@@ -336,28 +701,12 @@ int dnssec_verify_rrset(
qsort_safe(list, n, sizeof(DnsResourceRecord*), rr_compare);
/* OK, the RRs are now in canonical order. Let's calculate the digest */
- switch (rrsig->rrsig.algorithm) {
+ initialize_libgcrypt();
- case DNSSEC_ALGORITHM_RSASHA1:
- case DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1:
- gcry_md_open(&md, GCRY_MD_SHA1, 0);
- hash_size = 20;
- break;
-
- case DNSSEC_ALGORITHM_RSASHA256:
- gcry_md_open(&md, GCRY_MD_SHA256, 0);
- hash_size = 32;
- break;
-
- case DNSSEC_ALGORITHM_RSASHA512:
- gcry_md_open(&md, GCRY_MD_SHA512, 0);
- hash_size = 64;
- break;
-
- default:
- assert_not_reached("Unknown digest");
- }
+ hash_size = gcry_md_get_algo_dlen(md_algorithm);
+ assert(hash_size > 0);
+ gcry_md_open(&md, md_algorithm, 0);
if (!md)
return -EIO;
@@ -374,25 +723,30 @@ int dnssec_verify_rrset(
goto finish;
gcry_md_write(md, wire_format_name, r);
+ /* 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)
+ goto finish;
+
for (k = 0; k < n; k++) {
size_t l;
+
rr = list[k];
- r = dns_name_to_wire_format(DNS_RESOURCE_KEY_NAME(rr->key), wire_format_name, sizeof(wire_format_name), true);
- if (r < 0)
- goto finish;
+ /* Hash the source of synthesis. If this is a wildcard, then prefix it with the *. label */
+ if (wildcard)
+ gcry_md_write(md, (uint8_t[]) { 1, '*'}, 2);
gcry_md_write(md, wire_format_name, r);
md_add_uint16(md, rr->key->type);
md_add_uint16(md, rr->key->class);
md_add_uint32(md, rrsig->rrsig.original_ttl);
- assert(rr->wire_format_rdata_offset <= rr->wire_format_size);
- l = rr->wire_format_size - rr->wire_format_rdata_offset;
+ l = DNS_RESOURCE_RECORD_RDATA_SIZE(rr);
assert(l <= 0xFFFF);
md_add_uint16(md, (uint16_t) l);
- gcry_md_write(md, (uint8_t*) rr->wire_format + rr->wire_format_rdata_offset, l);
+ gcry_md_write(md, DNS_RESOURCE_RECORD_RDATA(rr), l);
}
hash = gcry_md_read(md, 0);
@@ -401,57 +755,44 @@ int dnssec_verify_rrset(
goto finish;
}
- 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)[0]) << 8) |
- ((size_t) ((uint8_t*) dnskey->dnskey.key)[1]);
-
- if (exponent_size < 256) {
- r = -EINVAL;
- goto finish;
- }
-
- if (3 + exponent_size >= dnskey->dnskey.key_size) {
- r = -EINVAL;
- goto finish;
- }
-
- 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) {
- r = -EINVAL;
- goto finish;
- }
+ switch (rrsig->rrsig.algorithm) {
- if (1 + exponent_size >= dnskey->dnskey.key_size) {
- r = -EINVAL;
- goto finish;
- }
+ case DNSSEC_ALGORITHM_RSASHA1:
+ case DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1:
+ case DNSSEC_ALGORITHM_RSASHA256:
+ case DNSSEC_ALGORITHM_RSASHA512:
+ r = dnssec_rsa_verify(
+ gcry_md_algo_name(md_algorithm),
+ hash, hash_size,
+ rrsig,
+ dnskey);
+ break;
- modulus = (uint8_t*) dnskey->dnskey.key + 1 + exponent_size;
- modulus_size = dnskey->dnskey.key_size - 1 - exponent_size;
+ case DNSSEC_ALGORITHM_ECDSAP256SHA256:
+ case DNSSEC_ALGORITHM_ECDSAP384SHA384:
+ r = dnssec_ecdsa_verify(
+ gcry_md_algo_name(md_algorithm),
+ rrsig->rrsig.algorithm,
+ hash, hash_size,
+ rrsig,
+ dnskey);
+ break;
}
- r = dnssec_rsa_verify(
- gcry_md_algo_name(gcry_md_get_algo(md)),
- rrsig->rrsig.signature, rrsig->rrsig.signature_size,
- hash, hash_size,
- exponent, exponent_size,
- modulus, modulus_size);
if (r < 0)
goto finish;
- *result = r ? DNSSEC_VALIDATED : DNSSEC_INVALID;
+ /* Now, fix the ttl, expiry, and remember the synthesizing source and the signer */
+ if (r > 0)
+ dnssec_fix_rrset_ttl(list, n, rrsig, realtime);
+
+ if (r == 0)
+ *result = DNSSEC_INVALID;
+ else if (wildcard)
+ *result = DNSSEC_VALIDATED_WILDCARD;
+ else
+ *result = DNSSEC_VALIDATED;
+
r = 0;
finish:
@@ -459,7 +800,7 @@ finish:
return r;
}
-int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey) {
+int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey, bool revoked_ok) {
assert(rrsig);
assert(dnskey);
@@ -476,18 +817,20 @@ int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnske
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) != rrsig->rrsig.key_tag)
+ 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(DnsResourceKey *key, DnsResourceRecord *rrsig) {
+int dnssec_key_match_rrsig(const DnsResourceKey *key, DnsResourceRecord *rrsig) {
assert(key);
assert(rrsig);
@@ -505,10 +848,11 @@ int dnssec_key_match_rrsig(DnsResourceKey *key, DnsResourceRecord *rrsig) {
int dnssec_verify_rrset_search(
DnsAnswer *a,
- DnsResourceKey *key,
+ const DnsResourceKey *key,
DnsAnswer *validated_dnskeys,
usec_t realtime,
- DnssecResult *result) {
+ DnssecResult *result,
+ DnsResourceRecord **ret_rrsig) {
bool found_rrsig = false, found_invalid = false, found_expired_rrsig = false, found_unsupported_algorithm = false;
DnsResourceRecord *rrsig;
@@ -517,7 +861,7 @@ int dnssec_verify_rrset_search(
assert(key);
assert(result);
- /* Verifies all RRs from "a" that match the key "key", against DNSKEY and DS RRs in "validated_dnskeys" */
+ /* Verifies all RRs from "a" that match the key "key" against DNSKEYs in "validated_dnskeys" */
if (!a || a->n_rrs <= 0)
return -ENODATA;
@@ -525,6 +869,7 @@ int dnssec_verify_rrset_search(
/* 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);
@@ -536,11 +881,14 @@ int dnssec_verify_rrset_search(
found_rrsig = true;
/* Look for a matching key */
- DNS_ANSWER_FOREACH(dnskey, validated_dnskeys) {
+ 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);
+ r = dnssec_rrsig_match_dnskey(rrsig, dnskey, false);
if (r < 0)
return r;
if (r == 0)
@@ -564,9 +912,13 @@ int dnssec_verify_rrset_search(
switch (one_result) {
case DNSSEC_VALIDATED:
+ case DNSSEC_VALIDATED_WILDCARD:
/* Yay, the RR has been validated,
- * return immediately. */
- *result = DNSSEC_VALIDATED;
+ * return immediately, but fix up the expiry */
+ if (ret_rrsig)
+ *ret_rrsig = rrsig;
+
+ *result = one_result;
return 0;
case DNSSEC_INVALID:
@@ -611,6 +963,26 @@ int dnssec_verify_rrset_search(
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 proctects 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;
}
@@ -625,23 +997,11 @@ int dnssec_canonicalize(const char *n, char *buffer, size_t buffer_max) {
return -ENOBUFS;
for (;;) {
- size_t i;
-
r = dns_label_unescape(&n, buffer, buffer_max);
if (r < 0)
return r;
if (r == 0)
break;
- if (r > 0) {
- int k;
-
- /* DNSSEC validation is always done on the ASCII version of the label */
- k = dns_label_apply_idna(buffer, r, buffer, buffer_max);
- if (k < 0)
- return k;
- if (k > 0)
- r = k;
- }
if (buffer_max < (size_t) r + 2)
return -ENOBUFS;
@@ -653,11 +1013,7 @@ int dnssec_canonicalize(const char *n, char *buffer, size_t buffer_max) {
if (memchr(buffer, '.', r))
return -EINVAL;
- for (i = 0; i < (size_t) r; i ++) {
- if (buffer[i] >= 'A' && buffer[i] <= 'Z')
- buffer[i] = buffer[i] - 'A' + 'a';
- }
-
+ ascii_strlower_n(buffer, (size_t) r);
buffer[r] = '.';
buffer += r + 1;
@@ -679,11 +1035,32 @@ int dnssec_canonicalize(const char *n, char *buffer, size_t buffer_max) {
return (int) c;
}
-int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *ds) {
- gcry_md_hd_t md = NULL;
+static int digest_to_gcrypt_md(uint8_t algorithm) {
+
+ /* Translates a DNSSEC digest algorithm into a gcrypt digest identifier */
+
+ switch (algorithm) {
+
+ case DNSSEC_DIGEST_SHA1:
+ return GCRY_MD_SHA1;
+
+ case DNSSEC_DIGEST_SHA256:
+ return GCRY_MD_SHA256;
+
+ case DNSSEC_DIGEST_SHA384:
+ return GCRY_MD_SHA384;
+
+ default:
+ return -EOPNOTSUPP;
+ }
+}
+
+int dnssec_verify_dnskey_by_ds(DnsResourceRecord *dnskey, DnsResourceRecord *ds, bool mask_revoke) {
char owner_name[DNSSEC_CANONICAL_HOSTNAME_MAX];
+ gcry_md_hd_t md = NULL;
+ size_t hash_size;
+ int md_algorithm, r;
void *result;
- int r;
assert(dnskey);
assert(ds);
@@ -696,48 +1073,41 @@ int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *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) != ds->ds.key_tag)
+ if (dnssec_keytag(dnskey, mask_revoke) != ds->ds.key_tag)
return 0;
- if (!dnssec_digest_supported(ds->ds.digest_type))
- return -EOPNOTSUPP;
+ initialize_libgcrypt();
- switch (ds->ds.digest_type) {
+ md_algorithm = digest_to_gcrypt_md(ds->ds.digest_type);
+ if (md_algorithm < 0)
+ return md_algorithm;
- case DNSSEC_DIGEST_SHA1:
+ hash_size = gcry_md_get_algo_dlen(md_algorithm);
+ assert(hash_size > 0);
- if (ds->ds.digest_size != 20)
- return 0;
-
- gcry_md_open(&md, GCRY_MD_SHA1, 0);
- break;
-
- case DNSSEC_DIGEST_SHA256:
-
- if (ds->ds.digest_size != 32)
- return 0;
-
- gcry_md_open(&md, GCRY_MD_SHA256, 0);
- break;
+ if (ds->ds.digest_size != hash_size)
+ return 0;
- default:
- assert_not_reached("Unknown digest");
- }
+ r = dnssec_canonicalize(DNS_RESOURCE_KEY_NAME(dnskey->key), owner_name, sizeof(owner_name));
+ if (r < 0)
+ return r;
+ gcry_md_open(&md, md_algorithm, 0);
if (!md)
return -EIO;
- r = dnssec_canonicalize(DNS_RESOURCE_KEY_NAME(dnskey->key), owner_name, sizeof(owner_name));
- if (r < 0)
- goto finish;
-
gcry_md_write(md, owner_name, r);
- md_add_uint16(md, dnskey->dnskey.flags);
+ 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);
@@ -755,8 +1125,9 @@ finish:
return r;
}
-int dnssec_verify_dnskey_search(DnsResourceRecord *dnskey, DnsAnswer *validated_ds) {
+int dnssec_verify_dnskey_by_ds_search(DnsResourceRecord *dnskey, DnsAnswer *validated_ds) {
DnsResourceRecord *ds;
+ DnsAnswerFlags flags;
int r;
assert(dnskey);
@@ -764,12 +1135,25 @@ int dnssec_verify_dnskey_search(DnsResourceRecord *dnskey, DnsAnswer *validated_
if (dnskey->key->type != DNS_TYPE_DNSKEY)
return 0;
- DNS_ANSWER_FOREACH(ds, validated_ds) {
+ 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(dnskey, ds);
+ 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)
@@ -779,15 +1163,961 @@ int dnssec_verify_dnskey_search(DnsResourceRecord *dnskey, DnsAnswer *validated_
return 0;
}
-static const char* const dnssec_mode_table[_DNSSEC_MODE_MAX] = {
- [DNSSEC_NO] = "no",
- [DNSSEC_TRUST] = "trust",
- [DNSSEC_YES] = "yes",
-};
-DEFINE_STRING_TABLE_LOOKUP(dnssec_mode, DnssecMode);
+static int nsec3_hash_to_gcrypt_md(uint8_t algorithm) {
+
+ /* Translates a DNSSEC NSEC3 hash algorithm into a gcrypt digest identifier */
+
+ switch (algorithm) {
+
+ case NSEC3_ALGORITHM_SHA1:
+ return GCRY_MD_SHA1;
+
+ default:
+ return -EOPNOTSUPP;
+ }
+}
+
+int dnssec_nsec3_hash(DnsResourceRecord *nsec3, const char *name, void *ret) {
+ uint8_t wire_format[DNS_WIRE_FOMAT_HOSTNAME_MAX];
+ gcry_md_hd_t md = NULL;
+ size_t hash_size;
+ int algorithm;
+ void *result;
+ unsigned k;
+ int r;
+
+ assert(nsec3);
+ assert(name);
+ assert(ret);
+
+ if (nsec3->key->type != DNS_TYPE_NSEC3)
+ return -EINVAL;
+
+ if (nsec3->nsec3.iterations > NSEC3_ITERATIONS_MAX) {
+ log_debug("Ignoring NSEC3 RR %s with excessive number of iterations.", dns_resource_record_to_string(nsec3));
+ return -EOPNOTSUPP;
+ }
+
+ algorithm = nsec3_hash_to_gcrypt_md(nsec3->nsec3.algorithm);
+ if (algorithm < 0)
+ return algorithm;
+
+ initialize_libgcrypt();
+
+ 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;
+
+ gcry_md_open(&md, algorithm, 0);
+ if (!md)
+ return -EIO;
+
+ gcry_md_write(md, wire_format, r);
+ gcry_md_write(md, nsec3->nsec3.salt, nsec3->nsec3.salt_size);
+
+ result = gcry_md_read(md, 0);
+ if (!result) {
+ r = -EIO;
+ goto finish;
+ }
+
+ for (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) {
+ r = -EIO;
+ goto finish;
+ }
+ }
+
+ memcpy(ret, result, hash_size);
+ r = (int) hash_size;
+
+finish:
+ gcry_md_close(md);
+ return r;
+}
+
+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 (nsec3_hash_to_gcrypt_md(rr->nsec3.algorithm) < 0)
+ return 0;
+ /* 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 (rr->n_skip_labels_source != 0)
+ return 0;
+ /* Ignore NSEC3 RRs that are located anywhere else than one label below the zone */
+ if (rr->n_skip_labels_signer != 1)
+ 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(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;
+ if (r == 0)
+ return 0;
+
+ b = DNS_RESOURCE_KEY_NAME(nsec3->key);
+ r = dns_name_parent(&b); /* strip off hash */
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return 0;
+
+ /* 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, NULL);
+ 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 the 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' */
+
+ /* 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;
+
+ if (!pp) {
+ /* 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;
+ }
+
+ /* 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));
+ 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 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 *common_suffix, *p;
+ int r;
+
+ assert(rr);
+ assert(rr->key->type == DNS_TYPE_NSEC);
+
+ /* Checks whether the "Next Closer" is witin the space covered by the specified RR. */
+
+ r = dns_name_common_suffix(DNS_RESOURCE_KEY_NAME(rr->key), rr->nsec.next_domain_name, &common_suffix);
+ if (r < 0)
+ return r;
+
+ for (;;) {
+ p = name;
+ r = dns_name_parent(&name);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return 0;
+
+ r = dns_name_equal(name, common_suffix);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ break;
+ }
+
+ /* p is now the "Next Closer". */
+
+ return dns_name_between(DNS_RESOURCE_KEY_NAME(rr->key), p, rr->nsec.next_domain_name);
+}
+
+static int dnssec_nsec_covers_wildcard(DnsResourceRecord *rr, const char *name) {
+ const char *common_suffix, *wc;
+ int r;
+
+ assert(rr);
+ assert(rr->key->type == DNS_TYPE_NSEC);
+
+ /* Checks whether the "Wildcard at the Closest Encloser" is within the space covered by the specified
+ * RR. Specifically, checks whether 'name' has the common suffix of the NSEC RR's owner and next names as
+ * suffix, and whether the NSEC covers the name generated by that suffix prepended with an asterisk label.
+ *
+ * NSEC bar → waldo.foo.bar: indicates that *.bar and *.foo.bar do not exist
+ * NSEC waldo.foo.bar → yyy.zzz.xoo.bar: indicates that *.xoo.bar and *.zzz.xoo.bar do not exist (and more ...)
+ * NSEC yyy.zzz.xoo.bar → bar: indicates that a number of wildcards don#t exist either...
+ */
+
+ r = dns_name_common_suffix(DNS_RESOURCE_KEY_NAME(rr->key), rr->nsec.next_domain_name, &common_suffix);
+ if (r < 0)
+ return r;
+
+ /* If the common suffix is not shared by the name we are interested in, it has nothing to say for us. */
+ r = dns_name_endswith(name, common_suffix);
+ if (r <= 0)
+ return r;
+
+ wc = strjoina("*.", common_suffix, NULL);
+ return dns_name_between(DNS_RESOURCE_KEY_NAME(rr->key), wc, rr->nsec.next_domain_name);
+}
+
+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 < 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;
+ }
+
+ /* Check if this NSEC RR proves the absence of a wildcard RR under this name */
+ r = dnssec_nsec_covers_wildcard(rr, name);
+ 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 approproate NSEC RR found, report this. */
+ *result = DNSSEC_NSEC_NO_RR;
+ return 0;
+}
+
+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 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;
+ if (r == 0)
+ return 0;
+
+ 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 = strappend("*.", 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);
+}
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",
@@ -795,5 +2125,7 @@ static const char* const dnssec_result_table[_DNSSEC_RESULT_MAX] = {
[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);
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-12-26 17:47:06 +0000