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Subject: Re: [RFC BlueZ] Adding support for blocking keys and mgmt tests.
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20191204013306.29935-1-alainm@chromium.org>
Date:   Thu, 5 Dec 2019 08:54:04 +0100
Cc:     linux-bluetooth@vger.kernel.org
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Message-Id: <D5E83A6A-608A-461D-8C8F-50C7A6F79C1B@holtmann.org>
References: <20191204013306.29935-1-alainm@chromium.org>
To:     Alain Michaud <alainm@chromium.org>
Sender: linux-bluetooth-owner@vger.kernel.org
Precedence: bulk

Hi Alain,

> Would love feedback on this.  Corresponding kernel change also sent for
> comments.
> 
> ---
> lib/mgmt.h       | 12 +++++++++
> src/adapter.c    | 67 ++++++++++++++++++++++++++++++++++++++++++++----
> unit/test-mgmt.c | 33 ++++++++++++++++++++++++
> 3 files changed, 107 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/mgmt.h b/lib/mgmt.h
> index 570dec997..fa50a3656 100644
> --- a/lib/mgmt.h
> +++ b/lib/mgmt.h
> @@ -583,6 +583,18 @@ struct mgmt_cp_set_phy_confguration {
> 	uint32_t	selected_phys;
> } __packed;
> 
> +#define MGMT_OP_SET_BLOCKED_KEYS	0x0046
> +struct mgmt_blocked_key_info {
> +	uint8_t type;
> +	uint8_t val[16];
> +} __packed;
> +
> +struct mgmt_cp_set_blocked_keys {
> +	uint16_t key_count;
> +	struct mgmt_blocked_key_info keys[0];
> +} __packed;
> +#define MGMT_OP_SET_BLOCKED_KEYS_SIZE 0
> +
> 
> #define MGMT_EV_CMD_COMPLETE		0x0001
> struct mgmt_ev_cmd_complete {
> diff --git a/src/adapter.c b/src/adapter.c
> index cef25616f..1b451af30 100644
> --- a/src/adapter.c
> +++ b/src/adapter.c
> @@ -99,6 +99,19 @@
> #define DISTANCE_VAL_INVALID	0x7FFF
> #define PATHLOSS_MAX		137
> 
> +/**
> + * These are known security keys that have been compromised.
> + * If this grows or there are needs to be platform specific, it is
> + * conceivable that these could be read from a config file.
> +*/ 
> +static const struct mgmt_blocked_key_info blocked_keys [] = {
> +	// Google Titan Security Keys
> +	{ 0x01 /* LTK */, {0xbf, 0x01, 0xfb, 0x9d, 0x4e, 0xf3, 0xbc, 0x36,
> +					0xd8, 0x74, 0xf5, 0x39, 0x41, 0x38, 0x68, 0x4c}},
> +	{ 0x02 /* IRK */, {0xa5, 0x99, 0xba, 0xe4, 0xe1, 0x7c, 0xa6, 0x18,
> +					0x22, 0x8e, 0x07, 0x56, 0xb4, 0xe8, 0x5f, 0x01}},
> +};
> +
> static DBusConnection *dbus_conn = NULL;
> 
> static bool kernel_conn_control = false;
> @@ -8827,6 +8840,40 @@ failed:
> 	btd_adapter_unref(adapter);
> }
> 
> +static void set_blocked_ltks_complete(uint8_t status, uint16_t length,
> +					const void *param, void *user_data)
> +{
> +	struct btd_adapter *adapter = user_data;
> +
> +	if (status != MGMT_STATUS_SUCCESS) {
> +		btd_error(adapter->dev_id,
> +				"Failed to set blocked LTKs: %s (0x%02x)",
> +				mgmt_errstr(status), status);
> +		return;
> +	}
> +
> +	DBG("Successfully set blocked keys for index %u", adapter->dev_id);
> +}
> +
> +static bool set_blocked_keys(uint16_t index, struct btd_adapter *adapter)
> +{
> +	uint8_t buffer[sizeof(struct mgmt_cp_set_blocked_keys) +
> +					sizeof(blocked_keys)] = { 0 };
> +	struct mgmt_cp_set_blocked_keys *cp =
> +					(struct mgmt_cp_set_blocked_keys *)buffer;
> +	int i;
> +
> +	cp->key_count = G_N_ELEMENTS(blocked_keys);
> +	for (i = 0; i < cp->key_count; ++i) {
> +		cp->keys[i].type = blocked_keys[i].type;
> +		memcpy(cp->keys[i].val, blocked_keys[i].val, sizeof(cp->keys[i].val));
> +	}
> +
> +	return mgmt_send(mgmt_master, MGMT_OP_SET_BLOCKED_KEYS, index,
> +					sizeof(buffer),	buffer,	read_info_complete, adapter, NULL);

wrong callback here.

> +}
> +
> +
> static void index_added(uint16_t index, uint16_t length, const void *param,
> 							void *user_data)
> {
> @@ -8861,15 +8908,25 @@ static void index_added(uint16_t index, uint16_t length, const void *param,
> 	 */
> 	adapter_list = g_list_append(adapter_list, adapter);
> 
> -	DBG("sending read info command for index %u", index);
> +	DBG("Setting blocked keys for index %u", index);
> +	if (!set_blocked_keys(index, adapter)){
> +		btd_error(adapter->dev_id,
> +			"Failed to set blocked keys for index %u", index);
> +		// TODO: Until the MGMT is ported to all kernels, this is best effort.
> +	}

Just check if the command is supported. We have a list of supported commands.

> 
> -	if (mgmt_send(mgmt_master, MGMT_OP_READ_INFO, index, 0, NULL,
> -					read_info_complete, adapter, NULL) > 0)
> -		return;
> +	DBG("sending read info command for index %u", index);
> 
> -	btd_error(adapter->dev_id,
> +	if (!mgmt_send(mgmt_master, MGMT_OP_READ_INFO, index, 0, NULL,
> +					read_info_complete, adapter, NULL) > 0) {
> +		btd_error(adapter->dev_id,
> 			"Failed to read controller info for index %u", index);
> +			goto unload;
> +	}
> +
> +	return;

We need to keep the read info the first command. The blocked keys setting should happen either just before loading the keys or right after.

> 
> +unload:
> 	adapter_list = g_list_remove(adapter_list, adapter);
> 
> 	btd_adapter_unref(adapter);
> diff --git a/unit/test-mgmt.c b/unit/test-mgmt.c
> index c67678b9a..d73c03f61 100644
> --- a/unit/test-mgmt.c
> +++ b/unit/test-mgmt.c
> @@ -256,6 +256,33 @@ static const struct command_test_data command_test_3 = {
> 	.rsp_status = MGMT_STATUS_INVALID_INDEX,
> };

Separate patch for the tests please and I think something went wrong in your email client or editor.

> 
> +static const unsigned char invalid_key_buffer[] =
> + { 0x01, 0x02 };
> +
> +static const struct command_test_data command_test_set_blocked_keys1 = {
> + .opcode = MGMT_OP_SET_BLOCKED_KEYS,
> + .index = MGMT_INDEX_NONE,
> + .cmd_data = invalid_key_buffer,
> + .cmd_size = sizeof(invalid_key_buffer),
> + .rsp_data = NULL,
> + .rsp_size = 0,
> + .rsp_status = MGMT_STATUS_INVALID_PARAMS,
> +};
> +
> +static const unsigned char valid_keys_buffer1[] =
> + { 0x01, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
> + 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f };
> +
> +static const struct command_test_data command_test_set_blocked_keys2 = {
> + .opcode = MGMT_OP_SET_BLOCKED_KEYS,
> + .index = MGMT_INDEX_NONE,
> + .cmd_data = valid_keys_buffer1,
> + .cmd_size = sizeof(valid_keys_buffer1),
> + .rsp_data = NULL,
> + .rsp_size = 0,
> + .rsp_status = MGMT_STATUS_SUCCESS,
> +};
> +
> static const unsigned char event_index_added[] =
> 				{ 0x04, 0x00, 0x01, 0x00, 0x00, 0x00 };
> 
> @@ -441,6 +468,12 @@ int main(int argc, char *argv[])
> 	g_test_add_data_func("/mgmt/response/2", &command_test_3,
> 								test_response);
> 
> +	g_test_add_data_func("/mgmt/command/set_blocked_keys1",
> +						&command_test_set_blocked_keys1, test_command);
> +
> +	g_test_add_data_func("/mgmt/command/set_blocked_keys2",
> +						&command_test_set_blocked_keys2, test_command);
> +
> 	g_test_add_data_func("/mgmt/event/1", &event_test_1, test_event);
> 	g_test_add_data_func("/mgmt/event/2", &event_test_1, test_event2);

Regards

Marcel