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Stable 26.3 Backport of #126138 - Revert "Revert "Verify the server certificate hostname on outbound TLS connections"" #2667

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Merged
zvonand merged 1 commit into from
Oct 25, 2026
+100 −3
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Stable 26.3 Backport of #126138 - Revert "Revert "Verify the server certificate hostname on outbound TLS connections"" #2667

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4 changes: 3 additions & 1 deletion base/poco/NetSSL_OpenSSL/src/SSLManager.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -340,7 +340,9 @@ void SSLManager::initDefaultContext(bool server)
{
_ptrDefaultClientContext->enableSessionCache(cacheSessions);
}
bool extendedVerification = config.getBool(prefix + CFG_EXTENDED_VERIFICATION, false);
/// Only an outbound connection has a requested host name to check: on an accepted socket this
/// would run against the client's address, which a client certificate does not name.
bool extendedVerification = config.getBool(prefix + CFG_EXTENDED_VERIFICATION, !server);
if (server)
_ptrDefaultServerContext->enableExtendedCertificateVerification(extendedVerification);
else
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2 changes: 1 addition & 1 deletion ...n/operations/server-configuration-parameters/_server_settings_outside_source.md
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Expand Up @@ -1194,7 +1194,7 @@ Keys for server/client settings:
| `certificateFile` | Path to the client/server certificate file in PEM format. You can omit it if `privateKeyFile` contains the certificate. | |
| `cipherList` | Supported OpenSSL encryptions. | `ALL:!ADH:!LOW:!EXP:!MD5:!3DES:@STRENGTH` |
| `disableProtocols` | Protocols that are not allowed to be used. | |
| `extendedVerification` | If enabled, verify that the certificate CN or SAN matches the peer hostname. | `false` |
| `extendedVerification` | If enabled, verify that the certificate CN or SAN matches the peer hostname. | `true` for `openSSL.client`, `false` for `openSSL.server` |
| `fips` | Activates OpenSSL FIPS mode. Supported if the library's OpenSSL version supports FIPS. | `false` |
| `invalidCertificateHandler` | Class (a subclass of CertificateHandler) for verifying invalid certificates. For example: `<invalidCertificateHandler> <name>RejectCertificateHandler</name> </invalidCertificateHandler>` . | `RejectCertificateHandler` |
| `loadDefaultCAFile` | Wether built-in CA certificates for OpenSSL will be used. ClickHouse assumes that builtin CA certificates are in the file `/etc/ssl/cert.pem` (resp. the directory `/etc/ssl/certs`) or in file (resp. directory) specified by the environment variable `SSL_CERT_FILE` (resp. `SSL_CERT_DIR`). | `true` |
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2 changes: 1 addition & 1 deletion src/Core/ServerSettings.cpp
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Expand Up @@ -1594,7 +1594,7 @@ Configured as `named_collections_storage.type` (`<named_collections_storage><typ
DECLARE(Bool, openssl_client_load_default_ca_file, true, R"(Determines whether built-in CA certificates for OpenSSL will be used. ClickHouse assumes that builtin CA certificates are in the file `</etc/ssl/cert.pem>` (resp. the directory `</etc/ssl/certs>`) or in file (resp. directory) specified by the environment variable `<SSL_CERT_FILE>` (resp. `<SSL_CERT_DIR>`).)", 0, "openSSL.client.loadDefaultCAFile") \
DECLARE(String, openssl_client_chipher_list, "ALL:!ADH:!LOW:!EXP:!MD5:!3DES:@STRENGTH", R"(Supported OpenSSL encryptions.)", 0, "openSSL.client.cipherList") \
DECLARE(Bool, openssl_client_cache_sessions, false, R"(Enables or disables caching sessions. Must be used in combination with `<sessionIdContext>`. Acceptable values: `<true>`, `<false>`.)", 0, "openSSL.client.cacheSessions") \
DECLARE(Bool, openssl_client_extended_verification, false, R"(If enabled, verify that the certificate CN or SAN matches the peer hostname.)", 0, "openSSL.client.extendedVerification") \
DECLARE(Bool, openssl_client_extended_verification, true, R"(If enabled, verify that the certificate CN or SAN matches the peer hostname.)", 0, "openSSL.client.extendedVerification") \
DECLARE(Bool, openssl_client_required_tls_v1, false, R"(Require a TLSv1 connection. Acceptable values: `<true>`, `<false>`.)", 0, "openSSL.client.requireTLSv1") \
DECLARE(Bool, openssl_client_required_tls_v1_1, false, R"(Require a TLSv1.1 connection. Acceptable values: `<true>`, `<false>`.)", 0, "openSSL.client.requireTLSv1_1") \
DECLARE(Bool, openssl_client_required_tls_v1_2, false, R"(Require a TLSv1.2 connection. Acceptable values: `<true>`, `<false>`.)", 0, "openSSL.client.requireTLSv1_2") \
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15 changes: 15 additions & 0 deletions tests/integration/test_accept_invalid_certificate/configs/ssl_config_ca_signed.xml
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@@ -0,0 +1,15 @@
<clickhouse>
<!-- Native interface with TLS, presenting a certificate that the client's CA signs but whose
name (CN=client) is not the address the client connects to.
-->
<tcp_port_secure>9440</tcp_port_secure>

<openSSL replace="replace">
<server> <!-- Used for https server AND secure tcp port -->
<certificateFile>/etc/clickhouse-server/config.d/client-cert.pem</certificateFile>
<privateKeyFile>/etc/clickhouse-server/config.d/client-key.pem</privateKeyFile>
<caConfig>/etc/clickhouse-server/config.d/ca-cert.pem</caConfig>
<verificationMode>none</verificationMode>
</server>
</openSSL>
</clickhouse>
69 changes: 69 additions & 0 deletions tests/integration/test_accept_invalid_certificate/test.py
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Expand Up @@ -8,6 +8,7 @@

SCRIPT_DIR = os.path.dirname(os.path.realpath(__file__))
MAX_RETRY = 5
CA_CERT = f"{SCRIPT_DIR}/certs/ca-cert.pem"

cluster = ClickHouseCluster(__file__)
instance = cluster.add_instance(
Expand All @@ -34,6 +35,18 @@
)


node2 = cluster.add_instance(
"node2",
main_configs=[
"configs/ssl_config_ca_signed.xml",
"certs/client-key.pem",
"certs/client-cert.pem",
"certs/ca-cert.pem",
],
with_zookeeper=False,
)


@pytest.fixture(scope="module", autouse=True)
def started_cluster():
try:
Expand All @@ -60,6 +73,36 @@ def started_cluster():
</connections_credentials>
</clickhouse>"""

# node2 presents a certificate this CA signs, so the chain is valid and only the name can fail.
config_ca_signed = """<clickhouse>
<openSSL>
<client>
<caConfig>{caConfig}</caConfig>
<loadDefaultCAFile>false</loadDefaultCAFile>
</client>
</openSSL>
</clickhouse>"""

config_ca_signed_sni_override = """<clickhouse>
<tls-sni-override>client</tls-sni-override>
<openSSL>
<client>
<caConfig>{caConfig}</caConfig>
<loadDefaultCAFile>false</loadDefaultCAFile>
</client>
</openSSL>
</clickhouse>"""

config_ca_signed_no_extended_verification = """<clickhouse>
<openSSL>
<client>
<caConfig>{caConfig}</caConfig>
<loadDefaultCAFile>false</loadDefaultCAFile>
<extendedVerification>false</extendedVerification>
</client>
</openSSL>
</clickhouse>"""


def execute_query_native(node, query, config):
config_path = f"{SCRIPT_DIR}/configs/client.xml"
Expand Down Expand Up @@ -131,3 +174,29 @@ def test_strict_connection_reject():
config_connection_accept.format(ip_address=f"{instance.ip_address}"),
)
assert "certificate verify failed" in str(err.value)


def test_hostname_mismatch_rejected_by_default():
with pytest.raises(Exception) as err:
execute_query_native(node2, "SELECT 1", config_ca_signed.format(caConfig=CA_CERT))
assert "Unacceptable certificate" in str(err.value)


def test_hostname_match_accepted():
assert (
execute_query_native(
node2, "SELECT 1", config_ca_signed_sni_override.format(caConfig=CA_CERT)
)
== "1\n"
)


def test_extended_verification_disabled():
assert (
execute_query_native(
node2,
"SELECT 1",
config_ca_signed_no_extended_verification.format(caConfig=CA_CERT),
)
== "1\n"
)
3 changes: 3 additions & 0 deletions tests/integration/test_acme_tls/configs/config.xml
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Expand Up @@ -14,6 +14,9 @@
</acme>
<openSSL>
<client>
<!-- Pebble is reached at a pinned address, and its serving certificate names
localhost, pebble and 127.0.0.1 only. -->
<extendedVerification>false</extendedVerification>
<invalidCertificateHandler>
<name>AcceptCertificateHandler</name>
</invalidCertificateHandler>
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3 changes: 3 additions & 0 deletions tests/integration/test_acme_tls/configs/config_multi.xml
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Expand Up @@ -14,6 +14,9 @@
</acme>
<openSSL>
<client>
<!-- Pebble is reached at a pinned address, and its serving certificate names
localhost, pebble and 127.0.0.1 only. -->
<extendedVerification>false</extendedVerification>
<invalidCertificateHandler>
<name>AcceptCertificateHandler</name>
</invalidCertificateHandler>
Expand Down
3 changes: 3 additions & 0 deletions tests/integration/test_bind_host/configs/config.d/ssl_conf.xml
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Expand Up @@ -7,6 +7,9 @@
<privateKeyFile>/etc/clickhouse-server/config.d/server.key</privateKeyFile>
</server>
<client>
<!-- This test asserts the source address a connection is made from, not the identity
of the peer, and server.crt names only localhost while the clusters use node1..4. -->
<extendedVerification>false</extendedVerification>
<invalidCertificateHandler>
<name>AcceptCertificateHandler</name>
</invalidCertificateHandler>
Expand Down
2 changes: 2 additions & 0 deletions tests/integration/test_ssl_cert_authentication/test.py
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Expand Up @@ -43,6 +43,7 @@ def started_cluster():


config = """<clickhouse>
<tls-sni-override>{sslHost}</tls-sni-override>
<openSSL>
<client>
<verificationMode>strict</verificationMode>
Expand All @@ -61,6 +62,7 @@ def execute_query_native(node, query, user, cert_name, password=None):
certificateFile=f"{SCRIPT_DIR}/certs/{cert_name}-cert.pem",
privateKeyFile=f"{SCRIPT_DIR}/certs/{cert_name}-key.pem",
caConfig=f"{SCRIPT_DIR}/certs/ca-cert.pem",
sslHost=SSL_HOST,
)

file = open(config_path, "w")
Expand Down
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