Tidy up EC parameter check code: instead of accessing internal structures
add utility functions to t1_lib.c to check if EC certificates and parameters
are consistent with peer.
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index 7a8dc31..ffc78c9 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -307,6 +307,30 @@
return 0;
}
}
+/* Get curves list, if "sess" is set return client curves otherwise
+ * preferred list
+ */
+static void tls1_get_curvelist(SSL *s, int sess,
+ const unsigned char **pcurves,
+ size_t *pcurveslen)
+ {
+ if (sess)
+ {
+ *pcurves = s->session->tlsext_ellipticcurvelist;
+ *pcurveslen = s->session->tlsext_ellipticcurvelist_length;
+ }
+ else
+ {
+ *pcurves = s->tlsext_ellipticcurvelist;
+ *pcurveslen = s->tlsext_ellipticcurvelist_length;
+ }
+ /* If not set use default: for now static structure */
+ if (!*pcurves)
+ {
+ *pcurves = eccurves_default;
+ *pcurveslen = sizeof(eccurves_default);
+ }
+ }
/* Return any common values from two lists. One list is used as a
* preference list where we return the most preferred match.
@@ -362,28 +386,10 @@
/* Can't do anything on client side */
if (s->server == 0)
return -1;
- /* Use our preferred curve list, if not set use default */
- if (s->tlsext_ellipticcurvelist)
- {
- l1 = s->tlsext_ellipticcurvelist;
- l1len = s->tlsext_ellipticcurvelist_length;
- }
- else
- {
- l1 = eccurves_default;
- l1len = sizeof(eccurves_default);
- }
- /* Use peer preferred curve list, if not set use default */
- if(s->session->tlsext_ellipticcurvelist)
- {
- l2 = s->session->tlsext_ellipticcurvelist;
- l2len =s->session->tlsext_ellipticcurvelist_length;
- }
- else
- {
- l2 = eccurves_default;
- l2len = sizeof(eccurves_default);
- }
+ /* Get supported curves */
+ tls1_get_curvelist(s, 0, &l1, &l1len);
+ tls1_get_curvelist(s, 1, &l2, &l2len);
+
id = tls1_shared_list(s, l1, l1len, l2, l2len, nmatch);
if (nmatch == -1)
return id;
@@ -466,6 +472,130 @@
return 0;
return tls1_set_curves(pext, pextlen, ncb.nid_arr, ncb.nidcnt);
}
+/* For an EC key set TLS id and required compression based on parameters */
+static int tls1_set_ec_id(unsigned char *curve_id, unsigned char *comp_id,
+ EC_KEY *ec)
+ {
+ int is_prime, id;
+ const EC_GROUP *grp;
+ const EC_POINT *pt;
+ const EC_METHOD *meth;
+ if (!ec)
+ return 0;
+ /* Determine if it is a prime field */
+ grp = EC_KEY_get0_group(ec);
+ pt = EC_KEY_get0_public_key(ec);
+ if (!grp || !pt)
+ return 0;
+ meth = EC_GROUP_method_of(grp);
+ if (!meth)
+ return 0;
+ if (EC_METHOD_get_field_type(meth) == NID_X9_62_prime_field)
+ is_prime = 1;
+ else
+ is_prime = 0;
+ /* Determine curve ID */
+ id = EC_GROUP_get_curve_name(grp);
+ id = tls1_ec_nid2curve_id(id);
+ /* If we have an ID set it, otherwise set arbitrary explicit curve */
+ if (id)
+ {
+ curve_id[0] = 0;
+ curve_id[1] = (unsigned char)id;
+ }
+ else
+ {
+ curve_id[0] = 0xff;
+ if (is_prime)
+ curve_id[1] = 0x01;
+ else
+ curve_id[1] = 0x02;
+ }
+ if (comp_id)
+ {
+ if (EC_KEY_get_conv_form(ec) == POINT_CONVERSION_COMPRESSED)
+ {
+ if (is_prime)
+ *comp_id = TLSEXT_ECPOINTFORMAT_ansiX962_compressed_prime;
+ else
+ *comp_id = TLSEXT_ECPOINTFORMAT_ansiX962_compressed_char2;
+ }
+ else
+ *comp_id = TLSEXT_ECPOINTFORMAT_uncompressed;
+ }
+ return 1;
+ }
+/* Check an EC key is compatible with extensions */
+static int tls1_check_ec_key(SSL *s,
+ unsigned char *curve_id, unsigned char *comp_id)
+ {
+ const unsigned char *p;
+ size_t plen, i;
+ /* If point formats extension present check it, otherwise everything
+ * is supported (see RFC4492).
+ */
+ if (comp_id && s->session->tlsext_ecpointformatlist)
+ {
+ p = s->session->tlsext_ecpointformatlist;
+ plen = s->session->tlsext_ecpointformatlist_length;
+ for (i = 0; i < plen; i++, p++)
+ {
+ if (*comp_id == *p)
+ break;
+ }
+ if (i == plen)
+ return 0;
+ }
+ /* If curve list present check it, otherwise everything is
+ * supported.
+ */
+ if (s->session->tlsext_ellipticcurvelist)
+ {
+ p = s->session->tlsext_ellipticcurvelist;
+ plen = s->session->tlsext_ellipticcurvelist_length;
+ for (i = 0; i < plen; i+=2, p+=2)
+ {
+ if (p[0] == curve_id[0] && p[1] == curve_id[1])
+ return 1;
+ }
+ return 0;
+ }
+ return 1;
+ }
+/* Check EC server key is compatible with client extensions */
+int tls1_check_ec_server_key(SSL *s)
+ {
+ int rv;
+ CERT_PKEY *cpk = s->cert->pkeys + SSL_PKEY_ECC;
+ EVP_PKEY *pkey;
+ unsigned char comp_id, curve_id[2];
+ if (!cpk->x509 || !cpk->privatekey)
+ return 0;
+ pkey = X509_get_pubkey(cpk->x509);
+ if (!pkey)
+ return 0;
+ rv = tls1_set_ec_id(curve_id, &comp_id, pkey->pkey.ec);
+ EVP_PKEY_free(pkey);
+ if (!rv)
+ return 0;
+ return tls1_check_ec_key(s, curve_id, &comp_id);
+ }
+/* Check EC temporary key is compatible with client extensions */
+int tls1_check_ec_tmp_key(SSL *s)
+ {
+ unsigned char curve_id[2];
+ EC_KEY *ec = s->cert->ecdh_tmp;
+ if (!ec)
+ {
+ if (s->cert->ecdh_tmp_cb)
+ return 1;
+ else
+ return 0;
+ }
+ if (!tls1_set_ec_id(curve_id, NULL, ec))
+ return 1;
+ return tls1_check_ec_key(s, curve_id, NULL);
+ }
#endif /* OPENSSL_NO_EC */
@@ -685,15 +815,7 @@
/* Add TLS extension EllipticCurves to the ClientHello message */
plist = s->tlsext_ellipticcurvelist;
- /* If we have a custom curve list use it otherwise
- * use default */
- if (plist)
- plistlen = s->tlsext_ellipticcurvelist_length;
- else
- {
- plist = eccurves_default;
- plistlen = sizeof(eccurves_default);
- }
+ tls1_get_curvelist(s, 0, &plist, &plistlen);
if ((lenmax = limit - ret - 6) < 0) return NULL;
if (plistlen > (size_t)lenmax) return NULL;
