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    SubjectRe: [PATCH v6 2/5] Bluetooth: aosp: surface AOSP quality report through mgmt
    Hi Joseph,

    On Thu, May 26, 2022 at 4:21 AM Joseph Hwang <josephsih@chromium.org> wrote:
    >
    > 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.
    >
    > Reported-by: kernel test robot <lkp@intel.com>
    >
    > Signed-off-by: Joseph Hwang <josephsih@chromium.org>
    > Reviewed-by: Archie Pusaka <apusaka@chromium.org>
    > ---
    >
    > Changes in v6:
    > - Fixed a sparse check warning about using static for evt_prefixes.
    >
    > Changes in v5:
    > - Define "struct ext_vendor_prefix" to replace "struct vendor_prefix"
    > so that extended vendor prefix = prefix + 1-octet subcode
    > - Define aosp_ext_prefix to provide AOSP extended prefix which is
    > returned by aosp_get_ext_prefix().
    > - Redefine struct ext_vendor_event_prefix such that
    > . it uses get_ext_vendor_prefix to get prefix and subcodes where
    > the prefix and the prefix length may be variable and are not
    > unknown until run time;
    > . it uses vendor_func to handle a vendor event
    > This table handles vendor events in a generic way.
    > - Rewrite hci_vendor_evt() so that it compares both vendor prefix
    > and subcode to match a vendor event.
    > - Define set_ext_prefix() to create MSFT extended vendor prefix
    > which is returned by msft_get_ext_prefix().
    > - Do not EXPORT_SYMBOL(mgmt_quality_report).
    > - Keep msft_get_ext_prefix in msft instead of hci_dev since it is
    > not used by any drivers.
    >
    > 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.
    >
    > include/net/bluetooth/hci_core.h | 12 +++++++
    > include/net/bluetooth/mgmt.h | 7 +++++
    > net/bluetooth/aosp.c | 50 +++++++++++++++++++++++++++++
    > net/bluetooth/aosp.h | 18 +++++++++++
    > net/bluetooth/hci_event.c | 54 +++++++++++++++++++++++++++++++-
    > net/bluetooth/mgmt.c | 19 +++++++++++
    > net/bluetooth/msft.c | 28 ++++++++++++++++-
    > net/bluetooth/msft.h | 12 +++++--
    > 8 files changed, 195 insertions(+), 5 deletions(-)
    >
    > diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
    > index 64d3a63759a8..f89738c6b973 100644
    > --- a/include/net/bluetooth/hci_core.h
    > +++ b/include/net/bluetooth/hci_core.h
    > @@ -328,6 +328,13 @@ struct amp_assoc {
    >
    > #define HCI_MAX_PAGES 3
    >
    > +struct ext_vendor_prefix {
    > + __u8 *prefix;
    > + __u8 prefix_len;
    > + __u8 *subcodes;
    > + __u8 subcodes_len;
    > +};
    > +
    > struct hci_dev {
    > struct list_head list;
    > struct mutex lock;
    > @@ -1876,6 +1883,8 @@ 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);
    > @@ -1894,4 +1903,7 @@ 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 c1c2fd72d9e3..6ccd0067c295 100644
    > --- a/include/net/bluetooth/mgmt.h
    > +++ b/include/net/bluetooth/mgmt.h
    > @@ -1127,3 +1127,10 @@ 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..94faa15b1ea0 100644
    > --- a/net/bluetooth/aosp.c
    > +++ b/net/bluetooth/aosp.c
    > @@ -199,3 +199,53 @@ int aosp_set_quality_report(struct hci_dev *hdev, bool enable)
    > else
    > return disable_quality_report(hdev);
    > }
    > +
    > +/* 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;
    > +}
    > +
    > +/* 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.
    > + * Since the AOSP does not define a prefix, its prefix is NULL
    > + * and prefix_len is 0.
    > + * While there are a number of subcodes in AOSP, only interested in
    > + * Bluetooth Quality Report (0x58) for now.
    > + */
    > +#define AOSP_EV_QUALITY_REPORT 0x58
    > +
    > +static unsigned char AOSP_SUBCODES[] = { AOSP_EV_QUALITY_REPORT };
    > +
    > +static struct ext_vendor_prefix aosp_ext_prefix = {
    > + .prefix = NULL,
    > + .prefix_len = 0,
    > + .subcodes = AOSP_SUBCODES,
    > + .subcodes_len = sizeof(AOSP_SUBCODES),
    > +};
    > +
    > +struct ext_vendor_prefix *aosp_get_ext_prefix(struct hci_dev *hdev)
    > +{
    > + return &aosp_ext_prefix;
    > +}
    > +
    > +void aosp_vendor_evt(struct hci_dev *hdev, 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..8208e01fffed 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);
    > +struct ext_vendor_prefix *aosp_get_ext_prefix(struct hci_dev *hdev);
    > +void aosp_vendor_evt(struct hci_dev *hdev, struct sk_buff *skb);
    >
    > #else
    >
    > @@ -26,4 +29,19 @@ 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 struct ext_vendor_prefix *
    > +aosp_get_ext_prefix(struct hci_dev *hdev)
    > +{
    > + return NULL;
    > +}
    > +
    > +static inline void aosp_vendor_evt(struct hci_dev *hdev, struct sk_buff *skb)
    > +{
    > +}
    > +
    > #endif
    > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
    > index 0270e597c285..8398971eddf4 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"
    > @@ -4259,6 +4260,57 @@ static void hci_num_comp_blocks_evt(struct hci_dev *hdev, void *data,
    > queue_work(hdev->workqueue, &hdev->tx_work);
    > }
    >
    > +/* Every distinct vendor specification must have a well-defined vendor
    > + * event prefix to determine if a vendor event meets the specification.
    > + * Some vendor prefixes are fixed values while some other vendor prefixes
    > + * are only available at run time.
    > + */
    > +static struct ext_vendor_event_prefix {
    > + /* Some vendor prefixes are variable length. For convenience,
    > + * the prefix in struct ext_vendor_prefix is in little endian.
    > + */
    > + struct ext_vendor_prefix *
    > + (*get_ext_vendor_prefix)(struct hci_dev *hdev);
    > + void (*vendor_func)(struct hci_dev *hdev, struct sk_buff *skb);
    > +} evt_prefixes[] = {
    > + { aosp_get_ext_prefix, aosp_vendor_evt },
    > + { msft_get_ext_prefix, 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, j;
    > + struct ext_vendor_prefix *vnd;
    > + __u8 subcode;
    > +
    > + for (i = 0; evt_prefixes[i].get_ext_vendor_prefix; i++) {
    > + vnd = evt_prefixes[i].get_ext_vendor_prefix(hdev);
    > + if (!vnd)
    > + continue;
    > +
    > + /* Compare the raw prefix data in little endian directly. */
    > + if (memcmp(vnd->prefix, skb->data, vnd->prefix_len))
    > + continue;
    > +
    > + /* Make sure that there are more data after prefix. */
    > + if (skb->len <= vnd->prefix_len)
    > + continue;
    > +
    > + /* The subcode is the single octet following the prefix. */
    > + subcode = skb->data[vnd->prefix_len];
    > + for (j = 0; j < vnd->subcodes_len; j++) {
    > + if (vnd->subcodes[j] == subcode) {
    > + evt_prefixes[i].vendor_func(hdev, skb);
    > + break;
    > + }
    > + }
    > + }
    > +}

    I recall saying that having such matching logic applied without the
    driver confirming that is the structure it using to be a bad idea
    since it could actually cause an event to misinterpret and cause bad
    behavior, instead we probably need a callback that gets populated by
    the driver e.g.(hdev->vendor_evt) then the driver can either populate
    with hci_vendor_evt if it does use prefixes or its own specialized
    function or NULL if it doesn't use vendor events, specially for old
    controllers Id leave it as NULL.

    > static void hci_mode_change_evt(struct hci_dev *hdev, void *data,
    > struct sk_buff *skb)
    > {
    > @@ -6879,7 +6931,7 @@ 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),
    > };
    >
    > 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 1ad84f34097f..9d3666bdd07c 100644
    > --- a/net/bluetooth/mgmt.c
    > +++ b/net/bluetooth/mgmt.c
    > @@ -4332,6 +4332,25 @@ 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);
    > +}
    > +
    > 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 f43994523b1f..c003e94faccd 100644
    > --- a/net/bluetooth/msft.c
    > +++ b/net/bluetooth/msft.c
    > @@ -116,6 +116,20 @@ bool msft_monitor_supported(struct hci_dev *hdev)
    > return !!(msft_get_features(hdev) & MSFT_FEATURE_MASK_LE_ADV_MONITOR);
    > }
    >
    > +/* Add the MSFT vendor event subcodes into MSFT_SUBCODES which
    > + * msft_vendor_evt() is interested in handling.
    > + */
    > +static unsigned char MSFT_SUBCODES[] = { MSFT_EV_LE_MONITOR_DEVICE };
    > +static struct ext_vendor_prefix msft_ext_prefix = { 0 };
    > +
    > +static void set_ext_prefix(struct msft_data *msft)
    > +{
    > + msft_ext_prefix.prefix = msft->evt_prefix;
    > + msft_ext_prefix.prefix_len = msft->evt_prefix_len;
    > + msft_ext_prefix.subcodes = MSFT_SUBCODES;
    > + msft_ext_prefix.subcodes_len = sizeof(MSFT_SUBCODES);
    > +}
    > +
    > static bool read_supported_features(struct hci_dev *hdev,
    > struct msft_data *msft)
    > {
    > @@ -156,6 +170,8 @@ static bool read_supported_features(struct hci_dev *hdev,
    > if (msft->features & MSFT_FEATURE_MASK_CURVE_VALIDITY)
    > hdev->msft_curve_validity = true;
    >
    > + set_ext_prefix(msft);
    > +
    > kfree_skb(skb);
    > return true;
    >
    > @@ -742,7 +758,17 @@ static void msft_monitor_device_evt(struct hci_dev *hdev, struct sk_buff *skb)
    > handle_data->mgmt_handle);
    > }
    >
    > -void msft_vendor_evt(struct hci_dev *hdev, void *data, struct sk_buff *skb)
    > +struct ext_vendor_prefix *msft_get_ext_prefix(struct hci_dev *hdev)
    > +{
    > + struct msft_data *msft = hdev->msft_data;
    > +
    > + if (!msft)
    > + return NULL;
    > +
    > + return &msft_ext_prefix;
    > +}
    > +
    > +void msft_vendor_evt(struct hci_dev *hdev, struct sk_buff *skb)
    > {
    > struct msft_data *msft = hdev->msft_data;
    > u8 *evt_prefix;
    > diff --git a/net/bluetooth/msft.h b/net/bluetooth/msft.h
    > index afcaf7d3b1cb..1515ae06c628 100644
    > --- a/net/bluetooth/msft.h
    > +++ b/net/bluetooth/msft.h
    > @@ -17,7 +17,7 @@ void msft_register(struct hci_dev *hdev);
    > void msft_unregister(struct hci_dev *hdev);
    > void msft_do_open(struct hci_dev *hdev);
    > void msft_do_close(struct hci_dev *hdev);
    > -void msft_vendor_evt(struct hci_dev *hdev, void *data, struct sk_buff *skb);
    > +void msft_vendor_evt(struct hci_dev *hdev, struct sk_buff *skb);
    > __u64 msft_get_features(struct hci_dev *hdev);
    > int msft_add_monitor_pattern(struct hci_dev *hdev, struct adv_monitor *monitor);
    > int msft_remove_monitor(struct hci_dev *hdev, struct adv_monitor *monitor,
    > @@ -27,6 +27,7 @@ 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);
    > +struct ext_vendor_prefix *msft_get_ext_prefix(struct hci_dev *hdev);
    >
    > #else
    >
    > @@ -39,8 +40,7 @@ static inline void msft_register(struct hci_dev *hdev) {}
    > static inline void msft_unregister(struct hci_dev *hdev) {}
    > static inline void msft_do_open(struct hci_dev *hdev) {}
    > static inline void msft_do_close(struct hci_dev *hdev) {}
    > -static inline void msft_vendor_evt(struct hci_dev *hdev, void *data,
    > - struct sk_buff *skb) {}
    > +static inline void msft_vendor_evt(struct hci_dev *hdev, struct sk_buff *skb) {}
    > static inline __u64 msft_get_features(struct hci_dev *hdev) { return 0; }
    > static inline int msft_add_monitor_pattern(struct hci_dev *hdev,
    > struct adv_monitor *monitor)
    > @@ -77,4 +77,10 @@ static inline bool msft_curve_validity(struct hci_dev *hdev)
    > return false;
    > }
    >
    > +static inline struct ext_vendor_prefix *
    > +msft_get_ext_prefix(struct hci_dev *hdev)
    > +{
    > + return NULL;
    > +}
    > +
    > #endif
    > --
    > 2.36.1.124.g0e6072fb45-goog
    >


    --
    Luiz Augusto von Dentz

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