vici: Make 96-bit truncation for SHA-256 configurable

src/libcharon/plugins/vici/vici_config.c

@@ -525,6 +525,7 @@ static void log_child_data(child_data_t *data, char *name)
 	DBG2(DBG_CFG, "   local_ts = %#R", data->local_ts);
 	DBG2(DBG_CFG, "   remote_ts = %#R", data->remote_ts);
 	DBG2(DBG_CFG, "   hw_offload = %u", cfg->options & OPT_HW_OFFLOAD);
+	DBG2(DBG_CFG, "   sha256_96 = %u", cfg->options & OPT_SHA256_96);
 }
 
 /**
@@ -891,6 +892,15 @@ CALLBACK(parse_opt_hw_offl, bool,
 	return parse_option(out, OPT_HW_OFFLOAD, v);
 }
 
+/**
+ * Parse OPT_SHA256_96 option
+ */
+CALLBACK(parse_opt_sha256_96, bool,
+	child_cfg_option_t *out, chunk_t v)
+{
+	return parse_option(out, OPT_SHA256_96, v);
+}
+
 /**
  * Parse an action_t
  */
@@ -1550,6 +1560,7 @@ CALLBACK(child_kv, bool,
 		{ "priority",			parse_uint32,		&child->cfg.priority				},
 		{ "interface",			parse_string,		&child->cfg.interface				},
 		{ "hw_offload",			parse_opt_hw_offl,	&child->cfg.options					},
+		{ "sha256_96",			parse_opt_sha256_96,&child->cfg.options					},
 	};
 
 	return parse_rules(rules, countof(rules), name, value,

src/swanctl/swanctl.opt

@@ -651,6 +651,15 @@ connections.<conn>.children.<child>.esp_proposals = default
 	for interoperability. If no algorithms are specified for AH nor ESP,
 	the _default_ set of algorithms for ESP is included.
 
+connections.<conn>.children.<child>.sha256_96 = no
+	Use incorrect 96-bit truncation for HMAC-SHA-256.
+
+	HMAC-SHA-256 is used with 128-bit truncation with IPsec. For compatibility
+	with implementations that incorrectly use 96-bit truncation this option may
+	be enabled to configure the shorter truncation length in the kernel.  This
+	is not negotiated, so this only works with peers that use the incorrect
+	truncation length (or have this option enabled).
+
 connections.<conn>.children.<child>.local_ts = dynamic
 	Local traffic selectors to include in CHILD_SA.