On Wed, Jun 26, 2024 at 6:46 AM Benjamin Tissoires bentiss@kernel.org wrote:
This allows to intercept and prevent or change the behavior of hid_hw_raw_request() from a bpf program.
The intent is to solve a couple of use case:
- firewalling a HID device: a firewall can monitor who opens the hidraw nodes and then prevent or allow access to write operations on that hidraw node.
- change the behavior of a device and emulate a new HID feature request
The hook is allowed to be run as sleepable so it can itself call hid_bpf_hw_request(), which allows to "convert" one feature request into another or even call the feature request on a different HID device on the same physical device.
Signed-off-by: Benjamin Tissoires bentiss@kernel.org
changes in v2:
- make use of SRCU
drivers/hid/bpf/hid_bpf_dispatch.c | 37 ++++++++++++++++++++++++++++++++++++ drivers/hid/bpf/hid_bpf_struct_ops.c | 1 + drivers/hid/hid-core.c | 6 ++++++ include/linux/hid_bpf.h | 35 ++++++++++++++++++++++++++++++++++ 4 files changed, 79 insertions(+)
diff --git a/drivers/hid/bpf/hid_bpf_dispatch.c b/drivers/hid/bpf/hid_bpf_dispatch.c index c026248e3d73..ac98bab4c96d 100644 --- a/drivers/hid/bpf/hid_bpf_dispatch.c +++ b/drivers/hid/bpf/hid_bpf_dispatch.c @@ -74,6 +74,43 @@ dispatch_hid_bpf_device_event(struct hid_device *hdev, enum hid_report_type type } EXPORT_SYMBOL_GPL(dispatch_hid_bpf_device_event);
+int dispatch_hid_bpf_raw_requests(struct hid_device *hdev,
unsigned char reportnum, u8 *buf,u32 size, enum hid_report_type rtype,enum hid_class_request reqtype,u64 source)+{
struct hid_bpf_ctx_kern ctx_kern = {.ctx = {.hid = hdev,.allocated_size = size,.size = size,},.data = buf,};struct hid_bpf_ops *e;int ret, idx;if (rtype >= HID_REPORT_TYPES)return -EINVAL;idx = srcu_read_lock(&hdev->bpf.srcu);list_for_each_entry_srcu(e, &hdev->bpf.prog_list, list,srcu_read_lock_held(&hdev->bpf.srcu)) {if (e->hid_hw_request) {ret = e->hid_hw_request(&ctx_kern.ctx, reportnum, rtype, reqtype, source);if (ret)goto out;}}
here and in patch 7 I would reduce indent by doing: if (!e->hid_hw_request) continue; ret = e->hid_hw_request(...);
otherwise lgtm