[PATCH HID v2 16/16] HID: bpf: make part of struct hid_device writable

Benjamin Tissoires
2024-06-07T15:29:10Z

It is useful to change the name, the phys and/or the uniq of a
struct hid_device during .rdesc_fixup().

For example, hid-uclogic.ko changes the uniq to store the firmware version
to differentiate between 2 devices sharing the same PID. In the same
way, changing the device name is useful when the device export 3 nodes,
all with the same name.

Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>

---

new in v2
---
drivers/hid/bpf/hid_bpf_struct_ops.c | 3 +++
include/linux/hid_bpf.h | 2 +-
2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/bpf/hid_bpf_struct_ops.c b/drivers/hid/bpf/hid_bpf_struct_ops.c
index 944e6d91a36b..14a4c64ae242 100644
--- a/drivers/hid/bpf/hid_bpf_struct_ops.c
+++ b/drivers/hid/bpf/hid_bpf_struct_ops.c
@@ -74,6 +74,9 @@ static int hid_bpf_ops_btf_struct_access(struct bpf_verifier_log *log,

const struct hid_bpf_offset_write_range write_ranges[] = {
WRITE_RANGE(hid_bpf_ctx, retval, 0, 0),
+ WRITE_RANGE(hid_device, name, 0, -1), /* minus 1 to ensure \0 at the end */
+ WRITE_RANGE(hid_device, uniq, 0, -1), /* minus 1 to ensure \0 at the end */
+ WRITE_RANGE(hid_device, phys, 0, -1), /* minus 1 to ensure \0 at the end */
};
#undef WRITE_RANGE
const struct btf_type *state = NULL;
diff --git a/include/linux/hid_bpf.h b/include/linux/hid_bpf.h
index 88ab4925bdaa..ff30cbc0a090 100644
--- a/include/linux/hid_bpf.h
+++ b/include/linux/hid_bpf.h
@@ -43,7 +43,7 @@ struct hid_device;
* ``hid`` and ``allocated_size`` are read-only, ``size`` and ``retval`` are read-write.
*/
struct hid_bpf_ctx {
- const struct hid_device *hid;
+ struct hid_device *hid;
__u32 allocated_size;
union {
__s32 retval;

--
2.44.0