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test DNS name constraints on CA are applied against Subject CN name when SAN name is unavailable
test correct CN with no SAN available is accepted
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Lines changed: 123 additions & 0 deletions

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‎tests/api/test_certman.c‎

Lines changed: 121 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1584,6 +1584,127 @@ int test_wolfSSL_CertManagerNameConstraint5(void)
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return EXPECT_RESULT();
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}
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int test_wolfSSL_CertManagerNameConstraint_DNS_CN(void)
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{
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EXPECT_DECLS;
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#if !defined(NO_FILESYSTEM) && !defined(NO_CERTS) && \
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!defined(NO_WOLFSSL_CM_VERIFY) && !defined(NO_RSA) && \
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defined(OPENSSL_EXTRA) && defined(WOLFSSL_CERT_GEN) && \
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defined(WOLFSSL_CERT_EXT) && defined(WOLFSSL_ALT_NAMES) && \
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!defined(NO_SHA256)
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/* Test that DNS name constraints are enforced against the Subject CN
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* when no SAN extension is present. The CA cert (cert-ext-ncdns.der)
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* permits only DNS:wolfssl.com and DNS:example.com. A leaf cert with
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* CN=evil.attacker.com and no SAN should be REJECTED. */
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WOLFSSL_CERT_MANAGER* cm = NULL;
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WOLFSSL_EVP_PKEY *priv = NULL;
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WOLFSSL_X509_NAME* name = NULL;
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const char* ca_cert = "./certs/test/cert-ext-ncdns.der";
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const char* server_cert = "./certs/test/server-goodcn.pem";
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byte *der = NULL;
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int derSz;
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byte *pt;
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WOLFSSL_X509 *x509 = NULL;
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WOLFSSL_X509 *ca = NULL;
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pt = (byte*)server_key_der_2048;
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ExpectNotNull(priv = wolfSSL_d2i_PrivateKey(EVP_PKEY_RSA, NULL,
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(const unsigned char**)&pt, sizeof_server_key_der_2048));
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ExpectNotNull(cm = wolfSSL_CertManagerNew());
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ExpectNotNull(ca = wolfSSL_X509_load_certificate_file(ca_cert,
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WOLFSSL_FILETYPE_ASN1));
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ExpectNotNull((der = (byte*)wolfSSL_X509_get_der(ca, &derSz)));
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ExpectIntEQ(wolfSSL_CertManagerLoadCABuffer(cm, der, derSz,
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WOLFSSL_FILETYPE_ASN1), WOLFSSL_SUCCESS);
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/* Sanity check: cert with SAN=evil.attacker.com is correctly rejected */
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ExpectNotNull(x509 = wolfSSL_X509_load_certificate_file(server_cert,
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WOLFSSL_FILETYPE_PEM));
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ExpectNotNull(name = wolfSSL_X509_get_subject_name(ca));
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ExpectIntEQ(wolfSSL_X509_set_issuer_name(x509, name), WOLFSSL_SUCCESS);
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name = NULL;
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ExpectNotNull(name = X509_NAME_new());
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ExpectIntEQ(X509_NAME_add_entry_by_txt(name, "countryName", MBSTRING_UTF8,
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(byte*)"US", 2, -1, 0), SSL_SUCCESS);
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ExpectIntEQ(X509_NAME_add_entry_by_txt(name, "commonName", MBSTRING_UTF8,
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(byte*)"evil.attacker.com", 17, -1, 0),
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SSL_SUCCESS);
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ExpectIntEQ(wolfSSL_X509_set_subject_name(x509, name), WOLFSSL_SUCCESS);
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X509_NAME_free(name);
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name = NULL;
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ExpectIntEQ(wolfSSL_X509_add_altname(x509, "evil.attacker.com",
1640+
ASN_DNS_TYPE), WOLFSSL_SUCCESS);
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ExpectIntGT(wolfSSL_X509_sign(x509, priv, EVP_sha256()), 0);
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ExpectNotNull((der = (byte*)wolfSSL_X509_get_der(x509, &derSz)));
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ExpectIntEQ(wolfSSL_CertManagerVerifyBuffer(cm, der, derSz,
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WOLFSSL_FILETYPE_ASN1), WC_NO_ERR_TRACE(ASN_NAME_INVALID_E));
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wolfSSL_X509_free(x509);
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x509 = NULL;
1647+
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/* NOW the actual vulnerability test: cert with CN=evil.attacker.com
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* but NO SAN. The DNS name constraint should still reject this, since
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* wolfSSL's hostname verification falls back to CN when no SAN exists. */
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ExpectNotNull(x509 = wolfSSL_X509_load_certificate_file(server_cert,
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WOLFSSL_FILETYPE_PEM));
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ExpectNotNull(name = wolfSSL_X509_get_subject_name(ca));
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ExpectIntEQ(wolfSSL_X509_set_issuer_name(x509, name), WOLFSSL_SUCCESS);
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name = NULL;
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ExpectNotNull(name = X509_NAME_new());
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ExpectIntEQ(X509_NAME_add_entry_by_txt(name, "countryName", MBSTRING_UTF8,
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(byte*)"US", 2, -1, 0), SSL_SUCCESS);
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ExpectIntEQ(X509_NAME_add_entry_by_txt(name, "commonName", MBSTRING_UTF8,
1661+
(byte*)"evil.attacker.com", 17, -1, 0),
1662+
SSL_SUCCESS);
1663+
ExpectIntEQ(wolfSSL_X509_set_subject_name(x509, name), WOLFSSL_SUCCESS);
1664+
X509_NAME_free(name);
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name = NULL;
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1667+
/* Do NOT add any SAN this is the bypass vector */
1668+
ExpectIntGT(wolfSSL_X509_sign(x509, priv, EVP_sha256()), 0);
1669+
ExpectNotNull((der = (byte*)wolfSSL_X509_get_der(x509, &derSz)));
1670+
/* Should be ASN_NAME_INVALID_E because CN violates the constraint */
1671+
ExpectIntEQ(wolfSSL_CertManagerVerifyBuffer(cm, der, derSz,
1672+
WOLFSSL_FILETYPE_ASN1), WC_NO_ERR_TRACE(ASN_NAME_INVALID_E));
1673+
wolfSSL_X509_free(x509);
1674+
x509 = NULL;
1675+
1676+
/* Positive test: CN matches a permitted name (wolfssl.com) and no SAN is
1677+
* present. The CN fallback should accept this cert. */
1678+
ExpectNotNull(x509 = wolfSSL_X509_load_certificate_file(server_cert,
1679+
WOLFSSL_FILETYPE_PEM));
1680+
ExpectNotNull(name = wolfSSL_X509_get_subject_name(ca));
1681+
ExpectIntEQ(wolfSSL_X509_set_issuer_name(x509, name), WOLFSSL_SUCCESS);
1682+
name = NULL;
1683+
1684+
ExpectNotNull(name = X509_NAME_new());
1685+
ExpectIntEQ(X509_NAME_add_entry_by_txt(name, "countryName", MBSTRING_UTF8,
1686+
(byte*)"US", 2, -1, 0), SSL_SUCCESS);
1687+
ExpectIntEQ(X509_NAME_add_entry_by_txt(name, "commonName", MBSTRING_UTF8,
1688+
(byte*)"wolfssl.com", 11, -1, 0),
1689+
SSL_SUCCESS);
1690+
ExpectIntEQ(wolfSSL_X509_set_subject_name(x509, name), WOLFSSL_SUCCESS);
1691+
X509_NAME_free(name);
1692+
name = NULL;
1693+
1694+
/* No SAN added; CN=wolfssl.com matches the permitted DNS constraint. */
1695+
ExpectIntGT(wolfSSL_X509_sign(x509, priv, EVP_sha256()), 0);
1696+
ExpectNotNull((der = (byte*)wolfSSL_X509_get_der(x509, &derSz)));
1697+
ExpectIntEQ(wolfSSL_CertManagerVerifyBuffer(cm, der, derSz,
1698+
WOLFSSL_FILETYPE_ASN1), WOLFSSL_SUCCESS);
1699+
1700+
wolfSSL_CertManagerFree(cm);
1701+
wolfSSL_X509_free(x509);
1702+
wolfSSL_X509_free(ca);
1703+
wolfSSL_EVP_PKEY_free(priv);
1704+
#endif
1705+
return EXPECT_RESULT();
1706+
}
1707+
15871708
int test_wolfSSL_CertManagerCRL(void)
15881709
{
15891710
EXPECT_DECLS;

‎tests/api/test_certman.h‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -35,6 +35,7 @@ int test_wolfSSL_CertManagerNameConstraint2(void);
3535
int test_wolfSSL_CertManagerNameConstraint3(void);
3636
int test_wolfSSL_CertManagerNameConstraint4(void);
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int test_wolfSSL_CertManagerNameConstraint5(void);
38+
int test_wolfSSL_CertManagerNameConstraint_DNS_CN(void);
3839
int test_wolfSSL_CertManagerCRL(void);
3940
int test_wolfSSL_CRL_reason_extensions_cleanup(void);
4041
int test_wolfSSL_CRL_static_revoked_list(void);
@@ -54,6 +55,7 @@ int test_various_pathlen_chains(void);
5455
TEST_DECL_GROUP("certman", test_wolfSSL_CertManagerNameConstraint3), \
5556
TEST_DECL_GROUP("certman", test_wolfSSL_CertManagerNameConstraint4), \
5657
TEST_DECL_GROUP("certman", test_wolfSSL_CertManagerNameConstraint5), \
58+
TEST_DECL_GROUP("certman", test_wolfSSL_CertManagerNameConstraint_DNS_CN), \
5759
TEST_DECL_GROUP("certman", test_wolfSSL_CertManagerCRL), \
5860
TEST_DECL_GROUP("certman", test_wolfSSL_CRL_reason_extensions_cleanup), \
5961
TEST_DECL_GROUP("certman", test_wolfSSL_CRL_static_revoked_list), \

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