Attention is currently required from: flichtenheld, stipa.
Hello flichtenheld, stipa,
I'd like you to reexamine a change. Please visit
http://gerrit.openvpn.net/c/openvpn/+/1826?usp=email
to look at the new patch set (#8).
Change subject: Make required action returned from pre_decrypt_verdict more
explicit
......................................................................
Make required action returned from pre_decrypt_verdict more explicit
The current code relies on the condition if state.server_session_id
is defined to decided if session_skip_to_pre_start should be used.
Instead explicitly return the intent and use that to decide if
session_skip_to_pre_start should be called.
Change-Id: Iccdd4cfad090c565aac27e16cdaa9871106c2f89
---
M src/openvpn/mudp.c
1 file changed, 43 insertions(+), 17 deletions(-)
git pull ssh://gerrit.openvpn.net:29418/openvpn refs/changes/26/1826/8
diff --git a/src/openvpn/mudp.c b/src/openvpn/mudp.c
index 632b064..dc049f6 100644
--- a/src/openvpn/mudp.c
+++ b/src/openvpn/mudp.c
@@ -87,9 +87,24 @@
"Reset packet from client, sending HMAC based reset
challenge", sock);
}
+/**
+ * Verdict if this packet should create a new session. If a packet is invalid
+ * or we send out an HMAC based challenge, we do not want to create a new
+ * session.
+ */
+enum pre_decrypt_verdict
+{
+ /** This packet should not create a new session */
+ PRE_DECRYPT_NO_ACTION,
+ /** This packet creates a new session normally */
+ PRE_DECRYPT_CREATE_SESSION,
+ /** Create a new session but skip the first two packets of
+ * the three way handshake */
+ PRE_DECRYPT_CREATE_SESSION_SKIP
+};
-/* Returns true if this packet should create a new session */
-static bool
+/** Returns a verdict if this packet should create a new session */
+static enum pre_decrypt_verdict
do_pre_decrypt_check(struct multi_context *m, struct tls_pre_decrypt_state
*state,
struct mroute_addr addr, struct link_socket *sock)
{
@@ -111,7 +126,7 @@
* responses */
if (!reflect_filter_rate_limit_check(m->initial_rate_limiter))
{
- return false;
+ return PRE_DECRYPT_NO_ACTION;
}
}
@@ -136,7 +151,7 @@
calculate_session_id_hmac(state->peer_session_id, from,
hmac_key, handwindow, 0);
send_hmac_reset_packet(m, state, tas, &sid, true, sock);
- return false;
+ return PRE_DECRYPT_NO_ACTION;
}
else
{
@@ -153,11 +168,11 @@
"ignoring connection attempt from old client (%s)",
peer);
gc_free(&gc);
- return false;
+ return PRE_DECRYPT_NO_ACTION;
}
else
{
- return true;
+ return PRE_DECRYPT_CREATE_SESSION;
}
}
}
@@ -170,7 +185,7 @@
send_hmac_reset_packet(m, state, tas, &sid, false, sock);
/* We have a reply do not create a new session */
- return false;
+ return PRE_DECRYPT_NO_ACTION;
}
else if (verdict == VERDICT_VALID_CONTROL_V1 || verdict ==
VERDICT_VALID_ACK_V1
|| verdict == VERDICT_VALID_WKC_V1)
@@ -181,6 +196,7 @@
bool pkt_is_ack = (verdict == VERDICT_VALID_ACK_V1);
bool ret = check_session_hmac_and_pkt_id(state, from, hmac_key,
handwindow, pkt_is_ack);
+ enum pre_decrypt_verdict action = PRE_DECRYPT_NO_ACTION;
const char *peer = print_link_socket_actual(&m->top.c2.from, &gc);
uint8_t pkt_firstbyte = *BPTR(&m->top.c2.buf);
@@ -198,14 +214,15 @@
"Valid packet (%s) with HMAC challenge from peer (%s), "
"accepting new connection.",
packet_opcode_name(op), peer);
+ action = PRE_DECRYPT_CREATE_SESSION_SKIP;
}
gc_free(&gc);
- return ret;
+ return action;
}
/* VERDICT_INVALID */
- return false;
+ return PRE_DECRYPT_NO_ACTION;
}
/**
@@ -220,9 +237,6 @@
struct link_socket *sock,
struct mroute_addr *real)
{
- struct hash *hash = m->hash;
- struct tls_pre_decrypt_state state = { 0 };
- struct multi_instance *mi = NULL;
struct gc_arena gc = gc_new();
if (m->deferred_shutdown_signal.signal_received)
@@ -231,8 +245,17 @@
"MULTI: Connection attempt from %s ignored while server is "
"shutting down",
mroute_addr_print(real, &gc));
+ gc_free(&gc);
+ return NULL;
}
- else if (do_pre_decrypt_check(m, &state, *real, sock))
+
+ struct hash *hash = m->hash;
+ struct tls_pre_decrypt_state state = { 0 };
+ struct multi_instance *mi = NULL;
+
+ enum pre_decrypt_verdict verdict = do_pre_decrypt_check(m, &state, *real,
sock);
+
+ if (verdict != PRE_DECRYPT_NO_ACTION)
{
/* This is an unknown session but with valid tls-auth/tls-crypt
* (or no auth at all). If this is the initial packet of a
@@ -257,13 +280,16 @@
/* If we have a session id already, ensure that the
* state is using the same */
- if (session_id_defined(&state.server_session_id)
- && session_id_defined((&state.peer_session_id)))
+ if (session_id_defined((&state.peer_session_id)))
{
- mi->context.c2.tls_multi->n_sessions++;
struct tls_session *session =
&mi->context.c2.tls_multi->session[TM_INITIAL];
- session_skip_to_pre_start(session, &state,
&m->top.c2.from);
+
+ if (verdict == PRE_DECRYPT_CREATE_SESSION_SKIP)
+ {
+ mi->context.c2.tls_multi->n_sessions++;
+ session_skip_to_pre_start(session, &state,
&m->top.c2.from);
+ }
}
}
}
--
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Gerrit-MessageType: newpatchset
Gerrit-Project: openvpn
Gerrit-Branch: master
Gerrit-Change-Id: Iccdd4cfad090c565aac27e16cdaa9871106c2f89
Gerrit-Change-Number: 1826
Gerrit-PatchSet: 8
Gerrit-Owner: plaisthos <[email protected]>
Gerrit-Reviewer: flichtenheld <[email protected]>
Gerrit-Reviewer: stipa <[email protected]>
Gerrit-CC: openvpn-devel <[email protected]>
Gerrit-Attention: flichtenheld <[email protected]>
Gerrit-Attention: stipa <[email protected]>
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