Received-SPF: pass (google.com: domain of linux-bluetooth-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220526112135.2486883-1-josephsih@chromium.org> <20220526192047.v6.2.I2015b42d2d0a502334c9c3a2983438b89716d4f0@changeid>
In-Reply-To: <20220526192047.v6.2.I2015b42d2d0a502334c9c3a2983438b89716d4f0@changeid>
From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date:   Thu, 26 May 2022 13:25:44 -0700
Message-ID: <CABBYNZLXzc2QDJ-8_XaoOSL+CXnrfHi-t8DPRTjO+wJjmCbV-w@mail.gmail.com>
Subject: Re: [PATCH v6 2/5] Bluetooth: aosp: surface AOSP quality report
 through mgmt
To:     Joseph Hwang <josephsih@chromium.org>
Cc:     linux-bluetooth@vger.kernel.org, marcel@holtmann.org,
        pali@kernel.org, chromeos-bluetooth-upstreaming@chromium.org,
        josephsih@google.com, kernel test robot <lkp@intel.com>,
        Archie Pusaka <apusaka@chromium.org>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        Paolo Abeni <pabeni@redhat.com>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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