Message-Id: <9F696602-8BAC-479E-998D-118DDAE54445@holtmann.org>
Date:   Thu, 17 Feb 2022 13:41:22 +0100
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Joseph Hwang <josephsih@...omium.org>
Cc:     BlueZ <linux-bluetooth@...r.kernel.org>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        Pali Rohár <pali@...nel.org>,
        CrosBT Upstreaming <chromeos-bluetooth-upstreaming@...omium.org>,
        Joseph Hwang <josephsih@...gle.com>,
        Archie Pusaka <apusaka@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        LKML <linux-kernel@...r.kernel.org>, netdev@...r.kernel.org
Subject: Re: [PATCH v4 1/3] Bluetooth: aosp: surface AOSP quality report
 through mgmt

Hi Joseph,

> When receiving a HCI vendor event, the kernel checks if it is an
> AOSP bluetooth quality report. If yes, the event is sent to bluez
> user space through the mgmt socket.
> 
> Signed-off-by: Joseph Hwang <josephsih@...omium.org>
> Reviewed-by: Archie Pusaka <apusaka@...omium.org>
> ---
> 
> (no changes since v3)
> 
> Changes in v3:
> - Rebase to resolve the code conflict.
> - Move aosp_quality_report_evt() from hci_event.c to aosp.c.
> - A new patch (3/3) is added to enable the quality report feature.
> 
> Changes in v2:
> - Scrap the two structures defined in aosp.c and use constants for
>  size check.
> - Do a basic size check about the quality report event. Do not pull
>  data from the event in which the kernel has no interest.
> - Define vendor event prefixes with which vendor events of distinct
>  vendor specifications can be clearly differentiated.
> - Use mgmt helpers to add the header and data to a mgmt skb.

this unsolicited vendor event business is giving me a headache. I assume it would be a lot simpler, but it doesn’t look like this. I need to spent some rounds of thinking to give you good advice. Unfortunately since we also want to support Intel vendor specific pieces, this is getting super complicated.

> include/net/bluetooth/hci_core.h |  5 ++
> include/net/bluetooth/mgmt.h     |  7 +++
> net/bluetooth/aosp.c             | 27 ++++++++++
> net/bluetooth/aosp.h             | 13 +++++
> net/bluetooth/hci_event.c        | 84 +++++++++++++++++++++++++++++++-
> net/bluetooth/mgmt.c             | 20 ++++++++
> net/bluetooth/msft.c             | 14 ++++++
> net/bluetooth/msft.h             | 12 +++++
> 8 files changed, 181 insertions(+), 1 deletion(-)
> 
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index f5caff1ddb29..ea83619ac4de 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -1864,6 +1864,8 @@ int mgmt_add_adv_patterns_monitor_complete(struct hci_dev *hdev, u8 status);
> int mgmt_remove_adv_monitor_complete(struct hci_dev *hdev, u8 status);
> void mgmt_adv_monitor_device_lost(struct hci_dev *hdev, u16 handle,
> 				  bdaddr_t *bdaddr, u8 addr_type);
> +int mgmt_quality_report(struct hci_dev *hdev, void *data, u32 data_len,
> +			u8 quality_spec);
> 
> u8 hci_le_conn_update(struct hci_conn *conn, u16 min, u16 max, u16 latency,
> 		      u16 to_multiplier);
> @@ -1882,4 +1884,7 @@ void hci_copy_identity_address(struct hci_dev *hdev, bdaddr_t *bdaddr,
> 
> #define TRANSPORT_TYPE_MAX	0x04
> 
> +#define QUALITY_SPEC_AOSP_BQR		0x0
> +#define QUALITY_SPEC_INTEL_TELEMETRY	0x1
> +
> #endif /* __HCI_CORE_H */
> diff --git a/include/net/bluetooth/mgmt.h b/include/net/bluetooth/mgmt.h
> index 3d26e6a3478b..83b602636262 100644
> --- a/include/net/bluetooth/mgmt.h
> +++ b/include/net/bluetooth/mgmt.h
> @@ -1120,3 +1120,10 @@ struct mgmt_ev_adv_monitor_device_lost {
> 	__le16 monitor_handle;
> 	struct mgmt_addr_info addr;
> } __packed;
> +
> +#define MGMT_EV_QUALITY_REPORT			0x0031
> +struct mgmt_ev_quality_report {
> +	__u8	quality_spec;
> +	__u32	data_len;
> +	__u8	data[];
> +} __packed;
> diff --git a/net/bluetooth/aosp.c b/net/bluetooth/aosp.c
> index 432ae3aac9e3..4a336433180d 100644
> --- a/net/bluetooth/aosp.c
> +++ b/net/bluetooth/aosp.c
> @@ -199,3 +199,30 @@ int aosp_set_quality_report(struct hci_dev *hdev, bool enable)
> 	else
> 		return disable_quality_report(hdev);
> }
> +
> +#define BLUETOOTH_QUALITY_REPORT_EV		0x58
> +
> +/* The following LEN = 1-byte Sub-event code + 48-byte Sub-event Parameters */
> +#define BLUETOOTH_QUALITY_REPORT_LEN		49
> +
> +bool aosp_check_quality_report_len(struct sk_buff *skb)
> +{
> +	/* skb->len is allowed to be larger than BLUETOOTH_QUALITY_REPORT_LEN
> +	 * to accommodate an additional Vendor Specific Parameter (vsp) field.
> +	 */
> +	if (skb->len < BLUETOOTH_QUALITY_REPORT_LEN) {
> +		BT_ERR("AOSP evt data len %d too short (%u expected)",
> +		       skb->len, BLUETOOTH_QUALITY_REPORT_LEN);
> +		return false;
> +	}
> +
> +	return true;
> +}
> +
> +void aosp_quality_report_evt(struct hci_dev *hdev,  void *data,
> +			     struct sk_buff *skb)
> +{
> +	if (aosp_has_quality_report(hdev) && aosp_check_quality_report_len(skb))
> +		mgmt_quality_report(hdev, skb->data, skb->len,
> +				    QUALITY_SPEC_AOSP_BQR);
> +}
> diff --git a/net/bluetooth/aosp.h b/net/bluetooth/aosp.h
> index 2fd8886d51b2..b21751e012de 100644
> --- a/net/bluetooth/aosp.h
> +++ b/net/bluetooth/aosp.h
> @@ -10,6 +10,9 @@ void aosp_do_close(struct hci_dev *hdev);
> 
> bool aosp_has_quality_report(struct hci_dev *hdev);
> int aosp_set_quality_report(struct hci_dev *hdev, bool enable);
> +bool aosp_check_quality_report_len(struct sk_buff *skb);
> +void aosp_quality_report_evt(struct hci_dev *hdev,  void *data,
> +			     struct sk_buff *skb);
> 
> #else
> 
> @@ -26,4 +29,14 @@ static inline int aosp_set_quality_report(struct hci_dev *hdev, bool enable)
> 	return -EOPNOTSUPP;
> }
> 
> +static inline bool aosp_check_quality_report_len(struct sk_buff *skb)
> +{
> +	return false;
> +}
> +
> +static inline void aosp_quality_report_evt(struct hci_dev *hdev,  void *data,
> +					   struct sk_buff *skb)
> +{
> +}
> +
> #endif
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 63b925921c87..6468ea0f71bd 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -37,6 +37,7 @@
> #include "smp.h"
> #include "msft.h"
> #include "eir.h"
> +#include "aosp.h"
> 
> #define ZERO_KEY "\x00\x00\x00\x00\x00\x00\x00\x00" \
> 		 "\x00\x00\x00\x00\x00\x00\x00\x00"
> @@ -4241,6 +4242,87 @@ static void hci_num_comp_blocks_evt(struct hci_dev *hdev, void *data,
> 	queue_work(hdev->workqueue, &hdev->tx_work);
> }
> 
> +/* Define the fixed vendor event prefixes below.
> + * Note: AOSP HCI Requirements use 0x54 and up as sub-event codes without
> + *       actually defining a vendor prefix. Refer to
> + *       https://source.android.com/devices/bluetooth/hci_requirements
> + *       Hence, the other vendor event prefixes should not use the same
> + *       space to avoid collision.
> + */
> +static unsigned char AOSP_BQR_PREFIX[] = { 0x58 };
> +
> +/* Some vendor prefixes are fixed values and lengths. */
> +#define FIXED_EVT_PREFIX(_prefix, _vendor_func)				\
> +{									\
> +	.prefix = _prefix,						\
> +	.prefix_len = sizeof(_prefix),					\
> +	.vendor_func = _vendor_func,					\
> +	.get_prefix = NULL,						\
> +	.get_prefix_len = NULL,						\
> +}
> +
> +/* Some vendor prefixes are only available at run time. The
> + * values and lengths are variable.
> + */
> +#define DYNAMIC_EVT_PREFIX(_prefix_func, _prefix_len_func, _vendor_func)\
> +{									\
> +	.prefix = NULL,							\
> +	.prefix_len = 0,						\
> +	.vendor_func = _vendor_func,					\
> +	.get_prefix = _prefix_func,					\
> +	.get_prefix_len = _prefix_len_func,				\
> +}
> +
> +/* Every distinct vendor specification must have a well-defined vendor
> + * event prefix to determine if a vendor event meets the specification.
> + * If an event prefix is fixed, it should be delcared with FIXED_EVT_PREFIX.
> + * Otherwise, DYNAMIC_EVT_PREFIX should be used for variable prefixes.
> + */
> +struct vendor_event_prefix {
> +	__u8 *prefix;
> +	__u8 prefix_len;
> +	void (*vendor_func)(struct hci_dev *hdev, void *data,
> +			    struct sk_buff *skb);
> +	__u8 *(*get_prefix)(struct hci_dev *hdev);
> +	__u8 (*get_prefix_len)(struct hci_dev *hdev);
> +} evt_prefixes[] = {
> +	FIXED_EVT_PREFIX(AOSP_BQR_PREFIX, aosp_quality_report_evt),
> +	DYNAMIC_EVT_PREFIX(get_msft_evt_prefix, get_msft_evt_prefix_len,
> +			   msft_vendor_evt),
> +
> +	/* end with a null entry */
> +	{},
> +};
> +
> +static void hci_vendor_evt(struct hci_dev *hdev, void *data,
> +			   struct sk_buff *skb)
> +{
> +	int i;
> +	__u8 *prefix;
> +	__u8 prefix_len;
> +
> +	for (i = 0; evt_prefixes[i].vendor_func; i++) {
> +		if (evt_prefixes[i].get_prefix)
> +			prefix = evt_prefixes[i].get_prefix(hdev);
> +		else
> +			prefix = evt_prefixes[i].prefix;
> +
> +		if (evt_prefixes[i].get_prefix_len)
> +			prefix_len = evt_prefixes[i].get_prefix_len(hdev);
> +		else
> +			prefix_len = evt_prefixes[i].prefix_len;
> +
> +		if (!prefix || prefix_len == 0)
> +			continue;
> +
> +		/* Compare the raw prefix data directly. */
> +		if (!memcmp(prefix, skb->data, prefix_len)) {
> +			evt_prefixes[i].vendor_func(hdev, data, skb);
> +			break;
> +		}
> +	}
> +}
> +
> static void hci_mode_change_evt(struct hci_dev *hdev, void *data,
> 				struct sk_buff *skb)
> {
> @@ -6844,7 +6926,7 @@ static const struct hci_ev {
> 	HCI_EV(HCI_EV_NUM_COMP_BLOCKS, hci_num_comp_blocks_evt,
> 	       sizeof(struct hci_ev_num_comp_blocks)),
> 	/* [0xff = HCI_EV_VENDOR] */
> -	HCI_EV_VL(HCI_EV_VENDOR, msft_vendor_evt, 0, HCI_MAX_EVENT_SIZE),
> +	HCI_EV_VL(HCI_EV_VENDOR, hci_vendor_evt, 0, HCI_MAX_EVENT_SIZE),
> };

I was thinking along the lines like this:

	HCI_EV_VND(evt_prefix, evt_prefix_len, callback),

So that we in the end can do things like this:

	HCI_EV_VL({ 0x58 }, 1, aosp_quality_report_evt),


> 
> static void hci_event_func(struct hci_dev *hdev, u8 event, struct sk_buff *skb,
> diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
> index 914e2f2d3586..5e48576041fb 100644
> --- a/net/bluetooth/mgmt.c
> +++ b/net/bluetooth/mgmt.c
> @@ -4389,6 +4389,26 @@ static int set_exp_feature(struct sock *sk, struct hci_dev *hdev,
> 			       MGMT_STATUS_NOT_SUPPORTED);
> }
> 
> +int mgmt_quality_report(struct hci_dev *hdev, void *data, u32 data_len,
> +			u8 quality_spec)
> +{
> +	struct mgmt_ev_quality_report *ev;
> +	struct sk_buff *skb;
> +
> +	skb = mgmt_alloc_skb(hdev, MGMT_EV_QUALITY_REPORT,
> +			     sizeof(*ev) + data_len);
> +	if (!skb)
> +		return -ENOMEM;
> +
> +	ev = skb_put(skb, sizeof(*ev));
> +	ev->quality_spec = quality_spec;
> +	ev->data_len = data_len;
> +	skb_put_data(skb, data, data_len);
> +
> +	return mgmt_event_skb(skb, NULL);
> +}
> +EXPORT_SYMBOL(mgmt_quality_report);
> +

I know what you want to do, but I can not let you call mgmt_ function from a driver. We need to make this cleaner and abstract so that the driver has a proper path to report it to hci_core and that decides then to send the report or not.

> static int get_device_flags(struct sock *sk, struct hci_dev *hdev, void *data,
> 			    u16 data_len)
> {
> diff --git a/net/bluetooth/msft.c b/net/bluetooth/msft.c
> index 9a3d77d3ca86..3edf64baf479 100644
> --- a/net/bluetooth/msft.c
> +++ b/net/bluetooth/msft.c
> @@ -731,6 +731,20 @@ static void msft_monitor_device_evt(struct hci_dev *hdev, struct sk_buff *skb)
> 				 handle_data->mgmt_handle);
> }
> 
> +__u8 *get_msft_evt_prefix(struct hci_dev *hdev)
> +{
> +	struct msft_data *msft = hdev->msft_data;
> +
> +	return msft->evt_prefix;
> +}
> +
> +__u8 get_msft_evt_prefix_len(struct hci_dev *hdev)
> +{
> +	struct msft_data *msft = hdev->msft_data;
> +
> +	return msft->evt_prefix_len;
> +}
> +

So I wonder if this should be moved directly into hci_dev under CONFIG_BT_MSFTEXT check. Luiz also needs to have a look at this. This is unfortunately getting a bit nasty now. We need to find a clean solution, otherwise the next vendor thing is blowing up in our face.

> void msft_vendor_evt(struct hci_dev *hdev, void *data, struct sk_buff *skb)
> {
> 	struct msft_data *msft = hdev->msft_data;
> diff --git a/net/bluetooth/msft.h b/net/bluetooth/msft.h
> index afcaf7d3b1cb..a354ebf61fed 100644
> --- a/net/bluetooth/msft.h
> +++ b/net/bluetooth/msft.h
> @@ -27,6 +27,8 @@ int msft_set_filter_enable(struct hci_dev *hdev, bool enable);
> int msft_suspend_sync(struct hci_dev *hdev);
> int msft_resume_sync(struct hci_dev *hdev);
> bool msft_curve_validity(struct hci_dev *hdev);
> +__u8 *get_msft_evt_prefix(struct hci_dev *hdev);
> +__u8 get_msft_evt_prefix_len(struct hci_dev *hdev);
> 
> #else
> 
> @@ -77,4 +79,14 @@ static inline bool msft_curve_validity(struct hci_dev *hdev)
> 	return false;
> }
> 
> +static inline __u8 *get_msft_evt_prefix(struct hci_dev *hdev)
> +{
> +	return NULL;
> +}
> +
> +static inline __u8 get_msft_evt_prefix_len(struct hci_dev *hdev)
> +{
> +	return 0;
> +}
> +
> #endif

Regards

Marcel

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