HID: bpf: make part of struct hid_device writable

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.

Link: https://lore.kernel.org/r/20240608-hid_bpf_struct_ops-v3-16-6ac6ade58329@kernel.org
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>

diff --git a/drivers/hid/bpf/hid_bpf_struct_ops.c b/drivers/hid/bpf/hid_bpf_struct_ops.c
index 3ba46c3cd87b9c7d4482f4d1de7eb563848495af..5f200557ff12b2b4fceb00d6d4d559b32bf91950 100644 (file)
--- 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, false),
+               WRITE_RANGE(hid_device, name, true),
+               WRITE_RANGE(hid_device, uniq, true),
+               WRITE_RANGE(hid_device, phys, true),
        };
 #undef WRITE_RANGE
        const struct btf_type *state = NULL;

diff --git a/include/linux/hid_bpf.h b/include/linux/hid_bpf.h
index 1b4cc1b2c31d4b430893aa64d76a0dfdad7cd91c..65d7e0acc8c23532dad5b721ac7068543be4cba3 100644 (file)
--- 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;