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ikev2: Delay IKE key derivation until next message

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In particular as responder, this delays costly cryptographic operations
until the IKE_AUTH request is received, which is preferable to reduce
the impact of DoS attacks.

Another advantage is that the key material is not changed until all tasks
built or processed a message.
This commit is contained in:
Tobias Brunner
2022-06-29 10:28:50 +02:00
parent 2a9323a18a
commit 44629bbadb
3 changed files with 173 additions and 45 deletions
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src/libcharon/sa/ikev2/task_manager_v2.c
+81 -24
View File
@@ -475,6 +475,40 @@ METHOD(task_manager_t, retransmit, status_t,
return INVALID_STATE;
}
/**
* Derive IKE keys if necessary
*/
static bool derive_keys(private_task_manager_t *this, array_t *tasks)
{
enumerator_t *enumerator;
task_t *task;
enumerator = array_create_enumerator(tasks);
while (enumerator->enumerate(enumerator, (void*)&task))
{
if (task->get_type(task) == TASK_IKE_INIT)
{
ike_init_t *ike_init = (ike_init_t*)task;
switch (ike_init->derive_keys(ike_init))
{
case SUCCESS:
array_remove_at(tasks, enumerator);
task->destroy(task);
break;
case NEED_MORE:
break;
default:
enumerator->destroy(enumerator);
return FALSE;
}
break;
}
}
enumerator->destroy(enumerator);
return TRUE;
}
METHOD(task_manager_t, initiate, status_t,
private_task_manager_t *this)
{
@@ -609,6 +643,11 @@ METHOD(task_manager_t, initiate, status_t,
}
else
{
if (!derive_keys(this, this->active_tasks))
{
return DESTROY_ME;
}
DBG2(DBG_IKE, "reinitiating already active tasks");
enumerator = array_create_enumerator(this->active_tasks);
while (enumerator->enumerate(enumerator, &task))
@@ -1531,6 +1570,36 @@ static status_t send_invalid_syntax(private_task_manager_t *this,
return DESTROY_ME;
}
/**
* Check for unsupported critical payloads
*/
static status_t has_unsupported_critical_payload(message_t *msg, uint8_t *type)
{
enumerator_t *enumerator;
unknown_payload_t *unknown;
payload_t *payload;
status_t status = SUCCESS;
enumerator = msg->create_payload_enumerator(msg);
while (enumerator->enumerate(enumerator, &payload))
{
if (payload->get_type(payload) == PL_UNKNOWN)
{
unknown = (unknown_payload_t*)payload;
if (unknown->is_critical(unknown))
{
*type = unknown->get_type(unknown);
DBG1(DBG_ENC, "payload type %N is not supported, "
"but payload is critical!", payload_type_names, *type);
status = NOT_SUPPORTED;
break;
}
}
}
enumerator->destroy(enumerator);
return status;
}
/**
* Parse the given message and verify that it is valid.
*/
@@ -1539,34 +1608,22 @@ static status_t parse_message(private_task_manager_t *this, message_t *msg)
status_t parse_status, status;
uint8_t type = 0;
parse_status = msg->parse_body(msg, this->ike_sa->get_keymat(this->ike_sa));
if (derive_keys(this, this->passive_tasks))
{
parse_status = msg->parse_body(msg, this->ike_sa->get_keymat(this->ike_sa));
if (parse_status == SUCCESS)
{ /* check for unsupported critical payloads */
enumerator_t *enumerator;
unknown_payload_t *unknown;
payload_t *payload;
enumerator = msg->create_payload_enumerator(msg);
while (enumerator->enumerate(enumerator, &payload))
if (parse_status == SUCCESS)
{
if (payload->get_type(payload) == PL_UNKNOWN)
{
unknown = (unknown_payload_t*)payload;
if (unknown->is_critical(unknown))
{
type = unknown->get_type(unknown);
DBG1(DBG_ENC, "payload type %N is not supported, "
"but payload is critical!", payload_type_names, type);
parse_status = NOT_SUPPORTED;
break;
}
}
parse_status = has_unsupported_critical_payload(msg, &type);
}
enumerator->destroy(enumerator);
}
status = parse_status;
status = parse_status;
}
else
{ /* there is no point in trying again */
parse_status = INVALID_STATE;
status = DESTROY_ME;
}
if (parse_status != SUCCESS)
{