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authorLennart Poettering <lennart@poettering.net>2015-12-27 21:35:00 +0100
committerLennart Poettering <lennart@poettering.net>2015-12-28 14:46:39 +0100
commite0240c64b76ba8f0c9219feb23a5783f23100216 (patch)
treec1da2d357ac8c1fa92e63860414f906acf029ed1 /src/resolve/resolved-dns-dnssec.c
parentc7feab764702e483ef84b47429387a9a54d451ff (diff)
resolved: add ECDSA signature support
Diffstat (limited to 'src/resolve/resolved-dns-dnssec.c')
-rw-r--r--src/resolve/resolved-dns-dnssec.c174
1 files changed, 166 insertions, 8 deletions
diff --git a/src/resolve/resolved-dns-dnssec.c b/src/resolve/resolved-dns-dnssec.c
index 263ab3f412..3e8766d73e 100644
--- a/src/resolve/resolved-dns-dnssec.c
+++ b/src/resolve/resolved-dns-dnssec.c
@@ -42,8 +42,7 @@
* - per-interface DNSSEC setting
* - fix TTL for cache entries to match RRSIG TTL
* - retry on failed validation?
- * - DSA support
- * - EC support?
+ * - DSA support?
*
* */
@@ -82,7 +81,9 @@ static bool dnssec_algorithm_supported(int algorithm) {
DNSSEC_ALGORITHM_RSASHA1,
DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1,
DNSSEC_ALGORITHM_RSASHA256,
- DNSSEC_ALGORITHM_RSASHA512);
+ DNSSEC_ALGORITHM_RSASHA512,
+ DNSSEC_ALGORITHM_ECDSAP256SHA256,
+ DNSSEC_ALGORITHM_ECDSAP384SHA384);
}
uint16_t dnssec_keytag(DnsResourceRecord *dnskey) {
@@ -282,6 +283,140 @@ static int dnssec_rsa_verify(
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));
}
@@ -342,8 +477,12 @@ static int algorithm_to_gcrypt(uint8_t algorithm) {
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;
@@ -480,11 +619,30 @@ int dnssec_verify_rrset(
goto finish;
}
- r = dnssec_rsa_verify(
- gcry_md_algo_name(algorithm),
- hash, hash_size,
- rrsig,
- dnskey);
+ switch (rrsig->rrsig.algorithm) {
+
+ 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(algorithm),
+ hash, hash_size,
+ rrsig,
+ dnskey);
+ break;
+
+ case DNSSEC_ALGORITHM_ECDSAP256SHA256:
+ case DNSSEC_ALGORITHM_ECDSAP384SHA384:
+ r = dnssec_ecdsa_verify(
+ gcry_md_algo_name(algorithm),
+ rrsig->rrsig.algorithm,
+ hash, hash_size,
+ rrsig,
+ dnskey);
+ break;
+ }
+
if (r < 0)
goto finish;