Add new "valid_flags" field to CERT_PKEY structure which determines what
the certificate can be used for (if anything). Set valid_flags field
in new tls1_check_chain function. Simplify ssl_set_cert_masks which used
to have similar checks in it.
Add new "cert_flags" field to CERT structure and include a "strict mode".
This enforces some TLS certificate requirements (such as only permitting
certificate signature algorithms contained in the supported algorithms
extension) which some implementations ignore: this option should be used
with caution as it could cause interoperability issues.
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index 88f70d7..add105d 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -539,24 +539,38 @@
}
return 1;
}
-/* Check EC server key is compatible with client extensions */
-int tls1_check_ec_server_key(SSL *s)
+
+/* Check cert parameters compatible with extensions: currently just checks
+ * EC certificates have compatible curves and compression.
+ */
+static int tls1_check_cert_param(SSL *s, X509 *x)
{
- 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);
+ EVP_PKEY *pkey;
+ int rv;
+ pkey = X509_get_pubkey(x);
if (!pkey)
return 0;
+ /* If not EC nothing to do */
+ if (pkey->type != EVP_PKEY_EC)
+ {
+ EVP_PKEY_free(pkey);
+ return 1;
+ }
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 server key is compatible with client extensions */
+int tls1_check_ec_server_key(SSL *s)
+ {
+ CERT_PKEY *cpk = s->cert->pkeys + SSL_PKEY_ECC;
+ if (!cpk->x509 || !cpk->privatekey)
+ return 0;
+ return tls1_check_cert_param(s, cpk->x509);
+ }
/* Check EC temporary key is compatible with client extensions */
int tls1_check_ec_tmp_key(SSL *s)
{
@@ -3050,24 +3064,30 @@
}
}
- /* Set any remaining keys to default values. NOTE: if alg is not
- * supported it stays as NULL.
+ /* In strict mode leave unset digests as NULL to indicate we can't
+ * use the certificate for signing.
*/
+ if (!(s->cert->cert_flags & SSL_CERT_FLAG_TLS_STRICT))
+ {
+ /* Set any remaining keys to default values. NOTE: if alg is
+ * not supported it stays as NULL.
+ */
#ifndef OPENSSL_NO_DSA
- if (!c->pkeys[SSL_PKEY_DSA_SIGN].digest)
- c->pkeys[SSL_PKEY_DSA_SIGN].digest = EVP_sha1();
+ if (!c->pkeys[SSL_PKEY_DSA_SIGN].digest)
+ c->pkeys[SSL_PKEY_DSA_SIGN].digest = EVP_sha1();
#endif
#ifndef OPENSSL_NO_RSA
- if (!c->pkeys[SSL_PKEY_RSA_SIGN].digest)
- {
- c->pkeys[SSL_PKEY_RSA_SIGN].digest = EVP_sha1();
- c->pkeys[SSL_PKEY_RSA_ENC].digest = EVP_sha1();
- }
+ if (!c->pkeys[SSL_PKEY_RSA_SIGN].digest)
+ {
+ c->pkeys[SSL_PKEY_RSA_SIGN].digest = EVP_sha1();
+ c->pkeys[SSL_PKEY_RSA_ENC].digest = EVP_sha1();
+ }
#endif
#ifndef OPENSSL_NO_ECDSA
- if (!c->pkeys[SSL_PKEY_ECC].digest)
- c->pkeys[SSL_PKEY_ECC].digest = EVP_sha1();
+ if (!c->pkeys[SSL_PKEY_ECC].digest)
+ c->pkeys[SSL_PKEY_ECC].digest = EVP_sha1();
#endif
+ }
return 1;
}
@@ -3360,4 +3380,147 @@
return 0;
}
+static int tls1_check_sig_alg(CERT *c, X509 *x, int default_nid)
+ {
+ int sig_nid;
+ size_t i;
+ if (default_nid == -1)
+ return 1;
+ sig_nid = X509_get_signature_nid(x);
+ if (default_nid)
+ return sig_nid == default_nid ? 1 : 0;
+ for (i = 0; i < c->shared_sigalgslen; i++)
+ if (sig_nid == c->shared_sigalgs[i].signandhash_nid)
+ return 1;
+ return 0;
+ }
+
+/* Check certificate chain is consistent with TLS extensions and is
+ * usable by server.
+ */
+int tls1_check_chain(SSL *s, X509 *x, EVP_PKEY *pk, STACK_OF(X509) *chain,
+ int idx)
+ {
+ int i;
+ int rv = CERT_PKEY_INVALID;
+ CERT_PKEY *cpk = NULL;
+ CERT *c = s->cert;
+ if (idx != -1)
+ {
+ cpk = c->pkeys + idx;
+ x = cpk->x509;
+ pk = cpk->privatekey;
+ chain = cpk->chain;
+ /* If no cert or key, forget it */
+ if (!x || !pk)
+ goto end;
+ }
+ else
+ {
+ idx = ssl_cert_type(x, pk);
+ if (idx == -1)
+ goto end;
+ }
+
+ /* Check all signature algorithms are consistent with
+ * signature algorithms extension if TLS 1.2 or later
+ * and strict mode.
+ */
+ if (TLS1_get_version(s) >= TLS1_2_VERSION
+ && c->cert_flags & SSL_CERT_FLAG_TLS_STRICT)
+ {
+ int default_nid;
+ unsigned char rsign = 0;
+ if (c->peer_sigalgs)
+ default_nid = 0;
+ /* If no sigalgs extension use defaults from RFC5246 */
+ else
+ {
+ switch(idx)
+ {
+ case SSL_PKEY_RSA_ENC:
+ case SSL_PKEY_RSA_SIGN:
+ case SSL_PKEY_DH_RSA:
+ rsign = TLSEXT_signature_rsa;
+ default_nid = NID_sha1WithRSAEncryption;
+ break;
+
+ case SSL_PKEY_DSA_SIGN:
+ case SSL_PKEY_DH_DSA:
+ rsign = TLSEXT_signature_dsa;
+ default_nid = NID_dsaWithSHA1;
+ break;
+
+ case SSL_PKEY_ECC:
+ rsign = TLSEXT_signature_ecdsa;
+ default_nid = NID_ecdsa_with_SHA1;
+ break;
+
+ default:
+ default_nid = -1;
+ break;
+ }
+ }
+ /* If peer sent no signature algorithms extension and we
+ * have set preferred signature algorithms check we support
+ * sha1.
+ */
+ if (default_nid > 0 && c->conf_sigalgs)
+ {
+ size_t j;
+ const unsigned char *p = c->conf_sigalgs;
+ for (j = 0; j < c->conf_sigalgslen; j += 2, p += 2)
+ {
+ if (p[0] == TLSEXT_hash_sha1 && p[1] == rsign)
+ break;
+ }
+ if (j == c->conf_sigalgslen)
+ goto end;
+ }
+ /* Check signature algorithm of each cert in chain */
+ if (!tls1_check_sig_alg(c, x, default_nid))
+ goto end;
+ for (i = 0; i < sk_X509_num(chain); i++)
+ {
+ if (!tls1_check_sig_alg(c, sk_X509_value(chain, i),
+ default_nid))
+ goto end;
+ }
+ }
+
+ /* Check cert parameters are consistent */
+ if (!tls1_check_cert_param(s, x))
+ goto end;
+ /* In strict mode check rest of chain too */
+ if (c->cert_flags & SSL_CERT_FLAG_TLS_STRICT)
+ {
+ for (i = 0; i < sk_X509_num(chain); i++)
+ {
+ if (!tls1_check_cert_param(s, sk_X509_value(chain, i)))
+ goto end;
+ }
+ }
+ rv = CERT_PKEY_VALID;
+
+ end:
+ if (cpk)
+ {
+ if (rv && cpk->digest)
+ rv |= CERT_PKEY_SIGN;
+ cpk->valid_flags = rv;
+ }
+ return rv;
+ }
+
+/* Set validity of certificates in an SSL structure */
+void tls1_set_cert_validity(SSL *s)
+ {
+ tls1_check_chain(s, NULL, NULL, NULL, SSL_PKEY_RSA_ENC);
+ tls1_check_chain(s, NULL, NULL, NULL, SSL_PKEY_RSA_SIGN);
+ tls1_check_chain(s, NULL, NULL, NULL, SSL_PKEY_DSA_SIGN);
+ tls1_check_chain(s, NULL, NULL, NULL, SSL_PKEY_DH_RSA);
+ tls1_check_chain(s, NULL, NULL, NULL, SSL_PKEY_DH_DSA);
+ tls1_check_chain(s, NULL, NULL, NULL, SSL_PKEY_ECC);
+ }
+
#endif
