output: support TLS version and cipher configuration

Adds support for `tls.min_version`, `tls.max_version`, and `tls.ciphers` in output instances.
Values are parsed and enforced during TLS context setup.

Signed-off-by: Eduardo Silva <[email protected]>

Author: Hiroshi Hatake

include/fluent-bit/flb_output.h

@@ -366,6 +366,9 @@ struct flb_output_instance {
     char *tls_crt_file;                  /* Certificate                  */
     char *tls_key_file;                  /* Cert Key                     */
     char *tls_key_passwd;                /* Cert Key Password            */
+    char *tls_min_version;               /* Minimum protocol version of TLS */
+    char *tls_max_version;               /* Maximum protocol version of TLS */
+    char *tls_ciphers;                   /* TLS ciphers */
 #endif
 
     /*

src/flb_output.c

@@ -115,6 +115,15 @@ static void flb_output_free_properties(struct flb_output_instance *ins)
     if (ins->tls_key_passwd) {
         flb_sds_destroy(ins->tls_key_passwd);
     }
+    if (ins->tls_min_version) {
+        flb_sds_destroy(ins->tls_min_version);
+    }
+    if (ins->tls_max_version) {
+        flb_sds_destroy(ins->tls_max_version);
+    }
+    if (ins->tls_ciphers) {
+        flb_sds_destroy(ins->tls_ciphers);
+    }
 #endif
 }
 
@@ -907,6 +916,15 @@ int flb_output_set_property(struct flb_output_instance *ins,
     else if (prop_key_check("tls.key_passwd", k, len) == 0) {
         flb_utils_set_plugin_string_property("tls.key_passwd", &ins->tls_key_passwd, tmp);
     }
+    else if (prop_key_check("tls.min_version", k, len) == 0) {
+        flb_utils_set_plugin_string_property("tls.min_version", &ins->tls_min_version, tmp);
+    }
+    else if (prop_key_check("tls.max_version", k, len) == 0) {
+        flb_utils_set_plugin_string_property("tls.max_version", &ins->tls_max_version, tmp);
+    }
+    else if (prop_key_check("tls.ciphers", k, len) == 0) {
+        flb_utils_set_plugin_string_property("tls.ciphers", &ins->tls_ciphers, tmp);
+    }
 #endif
     else if (prop_key_check("storage.total_limit_size", k, len) == 0 && tmp) {
         if (strcasecmp(tmp, "off") == 0 ||
@@ -1271,6 +1289,26 @@ int flb_output_init_all(struct flb_config *config)
                     return -1;
                 }
             }
+
+            if (ins->tls_min_version != NULL || ins->tls_max_version != NULL) {
+                ret = flb_tls_set_minmax_proto(ins->tls, ins->tls_min_version, ins->tls_max_version);
+                if (ret != 0) {
+                    flb_error("[output %s] error setting up minmax protocol version of TLS",
+                              ins->name);
+                    flb_output_instance_destroy(ins);
+                    return -1;
+                }
+            }
+
+            if (ins->tls_ciphers != NULL) {
+                ret = flb_tls_set_ciphers(ins->tls, ins->tls_ciphers);
+                if (ret != 0) {
+                    flb_error("[output %s] error setting up TLS ciphers up to TLSv1.2",
+                              ins->name);
+                    flb_output_instance_destroy(ins);
+                    return -1;
+                }
+            }
         }
 #endif
         /*