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Message-Id: <4E4ECD59-527D-4FDB-8EF8-21BC99FDE8D8@holtmann.org>
Date: Mon, 25 Oct 2021 15:18:11 +0200
From: Marcel Holtmann <marcel@...tmann.org>
To: Joseph Hwang <josephsih@...omium.org>
Cc: linux-bluetooth <linux-bluetooth@...r.kernel.org>,
Luiz Augusto von Dentz <luiz.dentz@...il.com>,
pali@...nel.org, chromeos-bluetooth-upstreaming@...omium.org,
josephsih@...gle.com, "David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Johan Hedberg <johan.hedberg@...il.com>,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v6 1/3] Bluetooth: Add struct of reading AOSP vendor
capabilities
Hi Jospeh,
> This patch adds the struct of reading AOSP vendor capabilities.
> New capabilities are added incrementally. Note that the
> version_supported octets will be used to determine whether a
> capability has been defined for the version.
>
> Signed-off-by: Joseph Hwang <josephsih@...omium.org>
>
> ---
>
> Changes in v6:
> - Add historical versions of struct aosp_rp_le_get_vendor_capabilities.
> - Perform the basic check about the struct length.
> - Through the version, bluetooth_quality_report_support can be checked.
>
> Changes in v5:
> - This is a new patch.
> - Add struct aosp_rp_le_get_vendor_capabilities so that next patch
> can determine whether a particular capability is supported or not.
>
> include/net/bluetooth/hci_core.h | 1 +
> net/bluetooth/aosp.c | 116 ++++++++++++++++++++++++++++++-
> 2 files changed, 116 insertions(+), 1 deletion(-)
>
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index dd8840e70e25..32b3774227f2 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -603,6 +603,7 @@ struct hci_dev {
>
> #if IS_ENABLED(CONFIG_BT_AOSPEXT)
> bool aosp_capable;
> + bool aosp_quality_report;
> #endif
>
> int (*open)(struct hci_dev *hdev);
> diff --git a/net/bluetooth/aosp.c b/net/bluetooth/aosp.c
> index a1b7762335a5..64684b2bf79b 100644
> --- a/net/bluetooth/aosp.c
> +++ b/net/bluetooth/aosp.c
> @@ -8,9 +8,53 @@
>
> #include "aosp.h"
>
> +/* Command complete parameters of LE_Get_Vendor_Capabilities_Command
> + * The parameters grow over time. The first version that declares the
> + * version_supported field is v0.95. Refer to
> + * https://cs.android.com/android/platform/superproject/+/master:system/
> + * bt/gd/hci/controller.cc;l=452?q=le_get_vendor_capabilities_handler
> + */
> +
> +/* the base capabilities struct with the version_supported field */
> +struct aosp_rp_le_get_vendor_capa_v95 {
> + __u8 status;
> + __u8 max_advt_instances;
> + __u8 offloaded_resolution_of_private_address;
> + __u16 total_scan_results_storage;
> + __u8 max_irk_list_sz;
> + __u8 filtering_support;
> + __u8 max_filter;
> + __u8 activity_energy_info_support;
> + __u16 version_supported;
> + __u16 total_num_of_advt_tracked;
> + __u8 extended_scan_support;
> + __u8 debug_logging_supported;
> +} __packed;
> +
> +struct aosp_rp_le_get_vendor_capa_v96 {
> + struct aosp_rp_le_get_vendor_capa_v95 v95;
> + /* v96 */
> + __u8 le_address_generation_offloading_support;
> +} __packed;
> +
> +struct aosp_rp_le_get_vendor_capa_v98 {
> + struct aosp_rp_le_get_vendor_capa_v96 v96;
> + /* v98 */
> + __u32 a2dp_source_offload_capability_mask;
> + __u8 bluetooth_quality_report_support;
> +} __packed;
> +
> +struct aosp_rp_le_get_vendor_capa_v100 {
> + struct aosp_rp_le_get_vendor_capa_v98 v98;
> + /* v100 */
> + __u32 dynamic_audio_buffer_support;
> +} __packed;
> +
while this is an interesting idea to document the different versions, I don’t thing you need to overboard like this. Just use the full struct and make sure you check the version_supported to ensure you are not reading beyond the bounds of your result.
Meaning you can have a struct pointer point to smaller memory, just make sure you never access it if it is not there. So I would just add defines for the different versions and their length of the struct.
Oh, I might have forgotten that, you need to use __le16 and __le32 to indicate the endianness of the data on the wire.
> void aosp_do_open(struct hci_dev *hdev)
> {
> struct sk_buff *skb;
> + struct aosp_rp_le_get_vendor_capa_v95 *base_rp;
> + u16 version_supported;
>
> if (!hdev->aosp_capable)
> return;
> @@ -20,9 +64,79 @@ void aosp_do_open(struct hci_dev *hdev)
> /* LE Get Vendor Capabilities Command */
> skb = __hci_cmd_sync(hdev, hci_opcode_pack(0x3f, 0x153), 0, NULL,
> HCI_CMD_TIMEOUT);
> - if (IS_ERR(skb))
> + if (IS_ERR(skb)) {
> + bt_dev_warn(hdev, "AOSP get vendor capabilities (%ld)",
> + PTR_ERR(skb));
This is actually an error. If the driver indicates support for it, this better succeed. If not complain loudly.
> return;
> + }
> +
> + bt_dev_dbg(hdev, "aosp le vendor capabilities length %d", skb->len);
Skip this one.
Add a basic length check that you know you can get to rp->version_supported field.
> +
> + base_rp = (struct aosp_rp_le_get_vendor_capa_v95 *)skb->data;
> +
> + if (base_rp->status) {
> + bt_dev_err(hdev, "AOSP LE Get Vendor Capabilities status %d",
> + base_rp->status);
> + goto done;
> + }
Actually the status is already evaluated via the __hci_cmd_sync command. No need to repeat it here.
> +
> + version_supported = le16_to_cpu(base_rp->version_supported);
> + bt_dev_info(hdev, "AOSP version %u", version_supported);
> +
> + /* Do not support very old versions. */
> + if (version_supported < 95) {
> + bt_dev_err(hdev, "capabilities version %u too old",
> + version_supported);
> + goto done;
> + }
This is not an error. Just print a warning here. And “AOSP capabilities ..” please.
> +
> + if (version_supported >= 95) {
> + struct aosp_rp_le_get_vendor_capa_v95 *rp;
> +
> + rp = (struct aosp_rp_le_get_vendor_capa_v95 *)skb->data;
> + if (skb->len < sizeof(*rp))
> + goto length_error;
> + }
> +
> + if (version_supported >= 96) {
> + struct aosp_rp_le_get_vendor_capa_v96 *rp;
> +
> + rp = (struct aosp_rp_le_get_vendor_capa_v96 *)skb->data;
> + if (skb->len < sizeof(*rp))
> + goto length_error;
> + }
Since we don’t use any data out of these two above, skip it. If the version is less than < 0.98 we are just ignoring it. You can print a warning that "AOSP quality report is not supported”.
> +
> + if (version_supported >= 98) {
> + struct aosp_rp_le_get_vendor_capa_v98 *rp;
> +
> + rp = (struct aosp_rp_le_get_vendor_capa_v98 *)skb->data;
> + if (skb->len < sizeof(*rp))
> + goto length_error;
> +
> + /* The bluetooth_quality_report_support is defined at version v0.98.
> + * Refer to https://cs.android.com/android/platform/superproject/+/
> + * master:system/bt/gd/hci/controller.cc;l=477
> + */
> + if (rp->bluetooth_quality_report_support) {
> + hdev->aosp_quality_report = true;
> + bt_dev_info(hdev, "bluetooth quality report is supported");
> + }
> + }
> +
> + if (version_supported >= 100) {
> + struct aosp_rp_le_get_vendor_capa_v100 *rp;
> +
> + rp = (struct aosp_rp_le_get_vendor_capa_v100 *)skb->data;
> + if (skb->len < sizeof(*rp))
> + goto length_error;
> + }
Skip that one as well. We only care about quality report support.
> +
> + goto done;
> +
> +length_error:
> + bt_dev_err(hdev, "AOSP capabilities length %d too short", skb->len);
>
> +done:
> kfree_skb(skb);
> }
Regards
Marcel
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