Add support for automatic client authentication via TLS certificate fields

src/acl.c

@@ -2575,6 +2575,8 @@ static void ACLUpdateInfoMetrics(int reason) {
         server.acl_info.invalid_key_accesses++;
     } else if (reason == ACL_DENIED_CHANNEL) {
         server.acl_info.invalid_channel_accesses++;
+    } else if (reason == ACL_INVALID_TLS_CERT_AUTH) {
+        server.acl_info.acl_access_denied_tls_cert++;
     } else {
         serverPanic("Unknown ACL_DENIED encoding");
     }
@@ -3016,6 +3018,7 @@ void aclCommand(client *c) {
             case ACL_DENIED_KEY: reasonstr = "key"; break;
             case ACL_DENIED_CHANNEL: reasonstr = "channel"; break;
             case ACL_DENIED_AUTH: reasonstr = "auth"; break;
+            case ACL_INVALID_TLS_CERT_AUTH: reasonstr = "tls-cert"; break;
             default: reasonstr = "unknown";
             }
             addReplyBulkCString(c, reasonstr);

src/config.c

@@ -118,6 +118,12 @@ configEnum tls_auth_clients_enum[] = {
     {"optional", TLS_CLIENT_AUTH_OPTIONAL},
     {NULL, 0}};
 
+configEnum tls_client_auth_user_enum[] = {
+    {"CN", TLS_CLIENT_FIELD_CN},
+    {"off", TLS_CLIENT_FIELD_OFF},
+    {NULL, 0} // terminator
+};
+
 configEnum oom_score_adj_enum[] = {
     {"no", OOM_SCORE_ADJ_NO},
     {"yes", OOM_SCORE_RELATIVE},
@@ -3372,6 +3378,7 @@ standardConfig static_configs[] = {
     createBoolConfig("tls-prefer-server-ciphers", NULL, MODIFIABLE_CONFIG, server.tls_ctx_config.prefer_server_ciphers, 0, NULL, applyTlsCfg),
     createBoolConfig("tls-session-caching", NULL, MODIFIABLE_CONFIG, server.tls_ctx_config.session_caching, 1, NULL, applyTlsCfg),
     createStringConfig("tls-cert-file", NULL, VOLATILE_CONFIG | MODIFIABLE_CONFIG, EMPTY_STRING_IS_NULL, server.tls_ctx_config.cert_file, NULL, NULL, applyTlsCfg),
+    createEnumConfig("tls-auth-clients-user", NULL, VOLATILE_CONFIG | MODIFIABLE_CONFIG, tls_client_auth_user_enum, server.tls_ctx_config.client_auth_user, TLS_CLIENT_FIELD_OFF, NULL, applyTlsCfg),
     createStringConfig("tls-key-file", NULL, VOLATILE_CONFIG | MODIFIABLE_CONFIG, EMPTY_STRING_IS_NULL, server.tls_ctx_config.key_file, NULL, NULL, applyTlsCfg),
     createStringConfig("tls-key-file-pass", NULL, MODIFIABLE_CONFIG | SENSITIVE_CONFIG, EMPTY_STRING_IS_NULL, server.tls_ctx_config.key_file_pass, NULL, NULL, applyTlsCfg),
     createStringConfig("tls-client-cert-file", NULL, VOLATILE_CONFIG | MODIFIABLE_CONFIG, EMPTY_STRING_IS_NULL, server.tls_ctx_config.client_cert_file, NULL, NULL, applyTlsCfg),

src/connection.h

@@ -137,6 +137,9 @@ typedef struct ConnectionType {
     /* TLS specified methods */
     sds (*get_peer_cert)(struct connection *conn);
 
+    /* Get peer username based on connection type */
+    sds (*get_peer_username)(connection *conn);
+
     /* Miscellaneous */
     int (*connIntegrityChecked)(void); // return 1 if connection type has built-in integrity checks
 } ConnectionType;
@@ -416,6 +419,14 @@ static inline sds connGetPeerCert(connection *conn) {
     return NULL;
 }
 
+/* Get Peer username based on connection type */
+static inline sds connGetPeerUsername(connection *conn) {
+    if (conn->type && conn->type->get_peer_username) {
+        return conn->type->get_peer_username(conn);
+    }
+    return NULL;
+}
+
 /* Initialize the connection framework */
 int connTypeInitialize(void);
 

src/networking.c

@@ -37,6 +37,7 @@
 #include "fmtargs.h"
 #include "io_threads.h"
 #include "module.h"
+#include "connection.h"
 #include <strings.h>
 #include <sys/socket.h>
 #include <sys/uio.h>
@@ -1682,6 +1683,21 @@ void clientAcceptHandler(connection *conn) {
         }
     }
 
+    /* Auto-authenticate from cert_user field if set */
+    sds username = connGetPeerUsername(conn);
+    if (username != NULL) {
+        user *u = ACLGetUserByName(username, sdslen(username));
+        if (u) {
+            c->user = u;
+            c->flag.authenticated = true;
+            serverLog(LL_VERBOSE, "TLS: Auto-authenticated client as %s",
+                      server.hide_user_data_from_log ? "*redacted*" : u->name);
+        } else {
+            addACLLogEntry(c, ACL_INVALID_TLS_CERT_AUTH, ACL_LOG_CTX_TOPLEVEL, 0, username, NULL);
+        }
+        sdsfree(username);
+    }
+
     server.stat_numconnections++;
     moduleFireServerEvent(VALKEYMODULE_EVENT_CLIENT_CHANGE, VALKEYMODULE_SUBEVENT_CLIENT_CHANGE_CONNECTED, c);
 }

src/server.c

@@ -2946,6 +2946,7 @@ void initServer(void) {
     server.acl_info.invalid_key_accesses = 0;
     server.acl_info.user_auth_failures = 0;
     server.acl_info.invalid_channel_accesses = 0;
+    server.acl_info.acl_access_denied_tls_cert = 0;
 
     /* Create the timer callback, this is our way to process many background
      * operations incrementally, like eviction of unaccessed expired keys, etc. */
@@ -5584,9 +5585,11 @@ sds genValkeyInfoStringACLStats(sds info) {
                         "acl_access_denied_auth:%lld\r\n"
                         "acl_access_denied_cmd:%lld\r\n"
                         "acl_access_denied_key:%lld\r\n"
-                        "acl_access_denied_channel:%lld\r\n",
+                        "acl_access_denied_channel:%lld\r\n"
+                        "acl_access_denied_tls_cert:%lld\r\n",
                         server.acl_info.user_auth_failures, server.acl_info.invalid_cmd_accesses,
-                        server.acl_info.invalid_key_accesses, server.acl_info.invalid_channel_accesses);
+                        server.acl_info.invalid_key_accesses, server.acl_info.invalid_channel_accesses,
+                        server.acl_info.acl_access_denied_tls_cert);
     return info;
 }
 

src/server.h

@@ -529,6 +529,10 @@ typedef enum {
 #define TLS_CLIENT_AUTH_YES 1
 #define TLS_CLIENT_AUTH_OPTIONAL 2
 
+/* TLS Client Certfiicate Authentication */
+#define TLS_CLIENT_FIELD_OFF 0
+#define TLS_CLIENT_FIELD_CN 1
+
 /* Sanitize dump payload */
 #define SANITIZE_DUMP_NO 0
 #define SANITIZE_DUMP_YES 1
@@ -1311,10 +1315,11 @@ typedef struct writePreparedClient writePreparedClient;
 
 /* ACL information */
 typedef struct aclInfo {
-    long long user_auth_failures;       /* Auth failure counts on user level */
-    long long invalid_cmd_accesses;     /* Invalid command accesses that user doesn't have permission to */
-    long long invalid_key_accesses;     /* Invalid key accesses that user doesn't have permission to */
-    long long invalid_channel_accesses; /* Invalid channel accesses that user doesn't have permission to */
+    long long user_auth_failures;         /* Auth failure counts on user level */
+    long long invalid_cmd_accesses;       /* Invalid command accesses that user doesn't have permission to */
+    long long invalid_key_accesses;       /* Invalid key accesses that user doesn't have permission to */
+    long long invalid_channel_accesses;   /* Invalid channel accesses that user doesn't have permission to */
+    long long acl_access_denied_tls_cert; /* TLS clients with cert not matching any existing user. */
 } aclInfo;
 
 struct saveparam {
@@ -1509,6 +1514,7 @@ typedef struct serverTLSContextConfig {
     char *client_cert_file;     /* Certificate to use as a client; if none, use cert_file */
     char *client_key_file;      /* Private key filename for client_cert_file */
     char *client_key_file_pass; /* Optional password for client_key_file */
+    int client_auth_user;       /* Field to be used for automatic TLS authentication based on client TLS certificate */
     char *dh_params_file;
     char *ca_cert_file;
     char *ca_cert_dir;
@@ -3069,8 +3075,9 @@ void ACLInit(void);
 #define ACL_OK 0
 #define ACL_DENIED_CMD 1
 #define ACL_DENIED_KEY 2
-#define ACL_DENIED_AUTH 3    /* Only used for ACL LOG entries. */
-#define ACL_DENIED_CHANNEL 4 /* Only used for pub/sub commands */
+#define ACL_DENIED_AUTH 3           /* Only used for ACL LOG entries. */
+#define ACL_DENIED_CHANNEL 4        /* Only used for pub/sub commands */
+#define ACL_INVALID_TLS_CERT_AUTH 5 /* Only used for TLS Auto-authentication */
 
 /* Context values for addACLLogEntry(). */
 #define ACL_LOG_CTX_TOPLEVEL 0

src/tls.c

@@ -41,6 +41,7 @@
 
 #include <openssl/conf.h>
 #include <openssl/ssl.h>
+#include <openssl/x509.h>
 #include <openssl/err.h>
 #include <openssl/rand.h>
 #include <openssl/pem.h>
@@ -679,6 +680,57 @@ static void updateSSLState(connection *conn_) {
     updatePendingData(conn);
 }
 
+static int getCertFieldByName(X509 *cert, const char *field, char *out, size_t outlen) {
+    if (!cert || !field || !out) return 0;
+
+    int nid = -1;
+
+    if (!strcasecmp(field, "CN"))
+        nid = NID_commonName;
+    else if (!strcasecmp(field, "O"))
+        nid = NID_organizationName;
+    /* Add more mappings here as needed */
+
+    if (nid == -1) return 0;
+
+    X509_NAME *subject = X509_get_subject_name(cert);
+    if (!subject) return 0;
+
+    return X509_NAME_get_text_by_NID(subject, nid, out, outlen) > 0;
+}
+
+sds tlsGetPeerUsername(connection *conn_) {
+    tls_connection *conn = (tls_connection *)conn_;
+    if (!conn || !SSL_is_init_finished(conn->ssl)) return NULL;
+
+    /* Find the corresponding field name from the enum mapping */
+    const char *field = NULL;
+    switch (server.tls_ctx_config.client_auth_user) {
+    case TLS_CLIENT_FIELD_CN:
+        field = "CN";
+        break;
+    default:
+        return NULL;
+    }
+
+    if (!field) return NULL;
+
+    X509 *cert = SSL_get_peer_certificate(conn->ssl);
+    if (!cert) return NULL;
+
+    char field_value[256];
+    sds result = NULL;
+
+    if (getCertFieldByName(cert, field, field_value, sizeof(field_value))) {
+        result = sdsnew(field_value);
+    } else {
+        serverLog(LL_NOTICE, "TLS: Failed to extract field '%s' from certificate", field);
+    }
+
+    X509_free(cert);
+    return result;
+}
+
 static void TLSAccept(void *_conn) {
     tls_connection *conn = (tls_connection *)_conn;
     ERR_clear_error();
@@ -1218,9 +1270,11 @@ static ConnectionType CT_TLS = {
 
     /* TLS specified methods */
     .get_peer_cert = connTLSGetPeerCert,
+    .get_peer_username = tlsGetPeerUsername,
 
     /* Miscellaneous */
     .connIntegrityChecked = connTLSIsIntegrityChecked,
+
 };
 
 int RedisRegisterConnectionTypeTLS(void) {

tests/unit/tls.tcl

@@ -154,5 +154,23 @@ start_server {tags {"tls"}} {
             r config set tls-key-file-pass 1234
             r config set tls-key-file $keyfile_encrypted
         }
+
+        test {TLS: Auto-authenticate using tls-auth-clients-user (CN)} {
+            # Create a user matching the CN in the client certificate (CN=Client-only)
+            r ACL SETUSER {Client-only} on >clientpass allcommands allkeys
+
+            # Enable the feature to auto-authenticate based on CN
+            r CONFIG SET tls-auth-clients-user CN
+
+            # With feature on, client should be auto-authenticated using CN=Client-only
+            set s [valkey [srv 0 host] [srv 0 port] 0 1]
+            ::tls::import [$s channel]
+
+            # Now no explicit AUTH is needed
+            assert_equal "PONG" [$s PING]
+
+            # Verify that the authenticated user is 'Client-only'
+            assert_equal "Client-only" [$s ACL WHOAMI]
+        }
     }
 }

valkey.conf

@@ -310,6 +310,21 @@ tcp-keepalive 300
 #
 # tls-session-cache-timeout 60
 
+# Automatically authenticate TLS clients as Valkey users based on their certificate.
+#
+# If set to a field like "CN", the server will extract the corresponding field from
+# the client's TLS certificate and attempt to find a Valkey user with the same name.
+# If a matching user is found, the client is automatically authenticated as that user
+# during the TLS handshake.
+#
+# If no matching user is found, the server falls back to the default user.
+#
+# Set to "off" to disable automatic user authentication via certificate fields.
+#
+# Supported values: CN, off. Default: off.
+#
+# tls-auth-clients-user CN
+
 ################################### RDMA ######################################
 
 # Valkey Over RDMA is experimental, it may be changed or be removed in any minor or major version.