Bluetooth: controller: Fix periph enc termination

Terminate connection with a MIC failure if an unexpected control PDU
is received during the Encryption Start procedure.

Add unit test inspired by Bluetooth Qualification test
LL/SEC/PER/BI-05-C,
Peripheral Receiving unexpected PDU during encryption start

Signed-off-by: Thomas Ebert Hansen <thoh@oticon.com>

subsys/bluetooth/controller/ll_sw/ull_llcp_enc.c

@@ -1168,7 +1168,23 @@ void llcp_rp_enc_rx(struct ll_conn *conn, struct proc_ctx *ctx, struct node_rx_p
 		break;
 	default:
 		/* Unknown opcode */
-		LL_ASSERT(0);
+
+		/*
+		 * BLUETOOTH CORE SPECIFICATION Version 5.3
+		 * Vol 6, Part B, 5.1.3.1 Encryption Start procedure
+		 *
+		 * [...]
+		 *
+		 * If, at any time during the encryption start procedure after the Peripheral has
+		 * received the LL_ENC_REQ PDU or the Central has received the
+		 * LL_ENC_RSP PDU, the Link Layer of the Central or the Peripheral receives an
+		 * unexpected Data Physical Channel PDU from the peer Link Layer, it shall
+		 * immediately exit the Connection state, and shall transition to the Standby state.
+		 * The Host shall be notified that the link has been disconnected with the error
+		 * code Connection Terminated Due to MIC Failure (0x3D).
+		 */
+
+		conn->llcp_terminate.reason_final = BT_HCI_ERR_TERM_DUE_TO_MIC_FAIL;
 	}
 }
 

tests/bluetooth/controller/ctrl_encrypt/src/main.c

@@ -1384,6 +1384,156 @@ void test_encryption_start_periph_rem_no_ltk(void)
 				  "Free CTX buffers %d", ctx_buffers_free());
 }
 
+/* +-----+                +-------+              +-----+
+ * | UT  |                | LL_A  |              | LT  |
+ * +-----+                +-------+              +-----+
+ *    |                       |                     |
+ *    |                       |          LL_ENC_REQ |
+ *    |                       |<--------------------|
+ *    |    -----------------\ |                     |
+ *    |    | Empty Tx queue |-|                     |
+ *    |    |----------------| |                     |
+ *    |                       |                     |
+ *    |                       | LL_ENC_RSP          |
+ *    |                       |-------------------->|
+ *    |                       |                     |
+ *    |                       |      LL_VERSION_IND |
+ *    |                       |<--------------------|
+ *    |                       |                     |
+ */
+void test_encryption_start_periph_rem_mic(void)
+{
+	struct node_tx *tx;
+	struct node_rx_pdu *ntf;
+
+	/* Prepare LL_ENC_REQ */
+	struct pdu_data_llctrl_enc_req enc_req = {
+		.rand = { RAND },
+		.ediv = { EDIV },
+		.skdm = { SKDM },
+		.ivm = { IVM },
+	};
+
+	struct pdu_data_llctrl_enc_rsp exp_enc_rsp = {
+		.skds = { SKDS },
+		.ivs = { IVS },
+	};
+
+	struct pdu_data_llctrl_version_ind remote_version_ind = {
+		.version_number = 0x55,
+		.company_id = 0xABCD,
+		.sub_version_number = 0x1234,
+	};
+
+	/* Prepare mocked call to lll_csrand_get */
+	ztest_returns_value(lll_csrand_get, sizeof(exp_enc_rsp.skds) + sizeof(exp_enc_rsp.ivs));
+	ztest_return_data(lll_csrand_get, buf, exp_enc_rsp.skds);
+	ztest_expect_value(lll_csrand_get, len, sizeof(exp_enc_rsp.skds) + sizeof(exp_enc_rsp.ivs));
+
+	/* Role */
+	test_set_role(&conn, BT_HCI_ROLE_PERIPHERAL);
+
+	/* Connect */
+	ull_cp_state_set(&conn, ULL_CP_CONNECTED);
+
+	/* Check state */
+	CHECK_RX_PE_STATE(conn, RESUMED, UNENCRYPTED); /* Rx unenc. */
+	CHECK_TX_PE_STATE(conn, RESUMED, UNENCRYPTED); /* Tx unenc. */
+
+	/* Prepare */
+	event_prepare(&conn);
+
+	/* Rx */
+	lt_tx(LL_ENC_REQ, &conn, &enc_req);
+
+	/* Check state */
+	CHECK_RX_PE_STATE(conn, RESUMED, UNENCRYPTED); /* Rx unenc. */
+	CHECK_TX_PE_STATE(conn, RESUMED, UNENCRYPTED); /* Tx unenc. */
+
+	/* Done */
+	event_done(&conn);
+
+	/* Check state */
+	CHECK_RX_PE_STATE(conn, PAUSED, UNENCRYPTED); /* Rx paused & unenc. */
+	CHECK_TX_PE_STATE(conn, PAUSED, UNENCRYPTED); /* Tx paused & unenc. */
+
+	/* Prepare */
+	event_prepare(&conn);
+
+	/* Tx Queue should have one LL Control PDU */
+	lt_rx(LL_ENC_RSP, &conn, &tx, &exp_enc_rsp);
+	lt_rx_q_is_empty(&conn);
+
+	/* Check state */
+	CHECK_RX_PE_STATE(conn, PAUSED, UNENCRYPTED); /* Rx paused & unenc. */
+	CHECK_TX_PE_STATE(conn, PAUSED, UNENCRYPTED); /* Tx paused & unenc. */
+
+	/* Done */
+	event_done(&conn);
+
+	/* Check state */
+	CHECK_RX_PE_STATE(conn, PAUSED, UNENCRYPTED); /* Rx paused & unenc. */
+	CHECK_TX_PE_STATE(conn, PAUSED, UNENCRYPTED); /* Tx paused & unenc. */
+
+	/* Release Tx */
+	ull_cp_release_tx(&conn, tx);
+
+	/* There should be a host notification */
+	ut_rx_pdu(LL_ENC_REQ, &ntf, &enc_req);
+	ut_rx_q_is_empty();
+
+	/* Release Ntf */
+	ull_cp_release_ntf(ntf);
+
+	/* Prepare */
+	event_prepare(&conn);
+
+	/* Rx */
+	lt_tx(LL_VERSION_IND, &conn, &remote_version_ind);
+
+	/* Done */
+	event_done(&conn);
+
+	/* Check state */
+	CHECK_RX_PE_STATE(conn, PAUSED, UNENCRYPTED); /* Rx paused & unenc. */
+	CHECK_TX_PE_STATE(conn, PAUSED, UNENCRYPTED); /* Tx paused & unenc. */
+
+	/* There should not be a host notification */
+	ut_rx_q_is_empty();
+
+	/**/
+	zassert_equal(conn.llcp_terminate.reason_final, BT_HCI_ERR_TERM_DUE_TO_MIC_FAIL,
+		      "Expected termination due to MIC failure");
+
+	/*
+	 * For a 40s procedure response timeout with a connection interval of
+	 * 7.5ms, a total of 5333.33 connection events are needed, verify that
+	 * the state doesn't change for that many invocations.
+	 */
+	for (int n = 5334; n > 0; n--) {
+		/* Prepare */
+		event_prepare(&conn);
+
+		/* Tx Queue should NOT have a LL Control PDU */
+		lt_rx_q_is_empty(&conn);
+
+		/* Done */
+		event_done(&conn);
+
+		/* Check state */
+		CHECK_RX_PE_STATE(conn, PAUSED, UNENCRYPTED); /* Rx paused & unenc. */
+		CHECK_TX_PE_STATE(conn, PAUSED, UNENCRYPTED); /* Tx paused & unenc. */
+
+		/* There should NOT be a host notification */
+		ut_rx_q_is_empty();
+	}
+
+	/* Note that for this test the context is not released */
+	zassert_equal(ctx_buffers_free(), test_ctx_buffers_cnt() - 1,
+				  "Free CTX buffers %d", ctx_buffers_free());
+}
+
+
 void test_encryption_pause_central_loc(void)
 {
 	uint8_t err;
@@ -1718,6 +1868,8 @@ void test_main(void)
 		ztest_unit_test_setup_teardown(test_encryption_start_periph_rem_limited_memory,
 					       setup, unit_test_noop),
 		ztest_unit_test_setup_teardown(test_encryption_start_periph_rem_no_ltk, setup,
+					       unit_test_noop),
+		ztest_unit_test_setup_teardown(test_encryption_start_periph_rem_mic, setup,
 					       unit_test_noop));
 
 	ztest_test_suite(encryption_pause,