@@ -28,8 +28,9 @@ EXPORT_SYMBOL(hid_bpf_ops);
*
* @ctx: The HID-BPF context
*
- * @return %0 on success and keep processing; a negative error code to interrupt
- * the processing of this event
+ * @return %0 on success and keep processing; a positive value to change the
+ * incoming size buffer; a negative error code to interrupt the processing
+ * of this event
*
* Declare an %fmod_ret tracing bpf program to this function and attach this
* program through hid_bpf_attach_prog() to have this helper called for
@@ -44,23 +45,43 @@ __weak noinline int hid_bpf_device_event(struct hid_bpf_ctx *ctx)
}
ALLOW_ERROR_INJECTION(hid_bpf_device_event, ERRNO);
-int
+u8 *
dispatch_hid_bpf_device_event(struct hid_device *hdev, enum hid_report_type type, u8 *data,
- u32 size, int interrupt)
+ u32 *size, int interrupt)
{
struct hid_bpf_ctx_kern ctx_kern = {
.ctx = {
.hid = hdev,
.report_type = type,
- .size = size,
+ .allocated_size = hdev->bpf.allocated_data,
+ .size = *size,
},
- .data = data,
+ .data = hdev->bpf.device_data,
};
+ int ret;
if (type >= HID_REPORT_TYPES)
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
+
+ /* no program has been attached yet */
+ if (!hdev->bpf.device_data)
+ return data;
+
+ memset(ctx_kern.data, 0, hdev->bpf.allocated_data);
+ memcpy(ctx_kern.data, data, *size);
+
+ ret = hid_bpf_prog_run(hdev, HID_BPF_PROG_TYPE_DEVICE_EVENT, &ctx_kern);
+ if (ret < 0)
+ return ERR_PTR(ret);
+
+ if (ret) {
+ if (ret > ctx_kern.ctx.allocated_size)
+ return ERR_PTR(-EINVAL);
- return hid_bpf_prog_run(hdev, HID_BPF_PROG_TYPE_DEVICE_EVENT, &ctx_kern);
+ *size = ret;
+ }
+
+ return ctx_kern.data;
}
EXPORT_SYMBOL_GPL(dispatch_hid_bpf_device_event);
@@ -83,7 +104,7 @@ hid_bpf_get_data(struct hid_bpf_ctx *ctx, unsigned int offset, const size_t rdwr
ctx_kern = container_of(ctx, struct hid_bpf_ctx_kern, ctx);
- if (rdwr_buf_size + offset > ctx->size)
+ if (rdwr_buf_size + offset > ctx->allocated_size)
return NULL;
return ctx_kern->data + offset;
@@ -110,6 +131,51 @@ static int device_match_id(struct device *dev, const void *id)
return hdev->id == *(int *)id;
}
+static int __hid_bpf_allocate_data(struct hid_device *hdev, u8 **data, u32 *size)
+{
+ u8 *alloc_data;
+ unsigned int i, j, max_report_len = 0;
+ size_t alloc_size = 0;
+
+ /* compute the maximum report length for this device */
+ for (i = 0; i < HID_REPORT_TYPES; i++) {
+ struct hid_report_enum *report_enum = hdev->report_enum + i;
+
+ for (j = 0; j < HID_MAX_IDS; j++) {
+ struct hid_report *report = report_enum->report_id_hash[j];
+
+ if (report)
+ max_report_len = max(max_report_len, hid_report_len(report));
+ }
+ }
+
+ /*
+ * Give us a little bit of extra space and some predictability in the
+ * buffer length we create. This way, we can tell users that they can
+ * work on chunks of 64 bytes of memory without having the bpf verifier
+ * scream at them.
+ */
+ alloc_size = DIV_ROUND_UP(max_report_len, 64) * 64;
+
+ alloc_data = kzalloc(alloc_size, GFP_KERNEL);
+ if (!alloc_data)
+ return -ENOMEM;
+
+ *data = alloc_data;
+ *size = alloc_size;
+
+ return 0;
+}
+
+static int hid_bpf_allocate_event_data(struct hid_device *hdev)
+{
+ /* hdev->bpf.device_data is already allocated, abort */
+ if (hdev->bpf.device_data)
+ return 0;
+
+ return __hid_bpf_allocate_data(hdev, &hdev->bpf.device_data, &hdev->bpf.allocated_data);
+}
+
/**
* hid_bpf_attach_prog - Attach the given @prog_fd to the given HID device
*
@@ -125,7 +191,7 @@ hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, __u32 flags)
{
struct hid_device *hdev;
struct device *dev;
- int prog_type = hid_bpf_get_prog_attach_type(prog_fd);
+ int err, prog_type = hid_bpf_get_prog_attach_type(prog_fd);
if (!hid_bpf_ops)
return -EINVAL;
@@ -145,6 +211,12 @@ hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, __u32 flags)
hdev = to_hid_device(dev);
+ if (prog_type == HID_BPF_PROG_TYPE_DEVICE_EVENT) {
+ err = hid_bpf_allocate_event_data(hdev);
+ if (err)
+ return err;
+ }
+
return __hid_bpf_attach_prog(hdev, prog_type, prog_fd, flags);
}
@@ -158,6 +230,30 @@ static const struct btf_kfunc_id_set hid_bpf_syscall_kfunc_set = {
.set = &hid_bpf_syscall_kfunc_ids,
};
+int hid_bpf_connect_device(struct hid_device *hdev)
+{
+ struct hid_bpf_prog_list *prog_list;
+
+ rcu_read_lock();
+ prog_list = rcu_dereference(hdev->bpf.progs[HID_BPF_PROG_TYPE_DEVICE_EVENT]);
+ rcu_read_unlock();
+
+ /* only allocate BPF data if there are programs attached */
+ if (!prog_list)
+ return 0;
+
+ return hid_bpf_allocate_event_data(hdev);
+}
+EXPORT_SYMBOL_GPL(hid_bpf_connect_device);
+
+void hid_bpf_disconnect_device(struct hid_device *hdev)
+{
+ kfree(hdev->bpf.device_data);
+ hdev->bpf.device_data = NULL;
+ hdev->bpf.allocated_data = 0;
+}
+EXPORT_SYMBOL_GPL(hid_bpf_disconnect_device);
+
void hid_bpf_destroy_device(struct hid_device *hdev)
{
if (!hdev)
@@ -122,8 +122,10 @@ int hid_bpf_prog_run(struct hid_device *hdev, enum hid_bpf_prog_type type,
ctx_kern->ctx.index = idx;
err = __hid_bpf_tail_call(&ctx_kern->ctx);
- if (err)
+ if (err < 0)
break;
+ if (err)
+ ctx_kern->ctx.retval = err;
}
out_unlock:
@@ -2040,9 +2040,11 @@ int hid_input_report(struct hid_device *hid, enum hid_report_type type, u8 *data
report_enum = hid->report_enum + type;
hdrv = hid->driver;
- ret = dispatch_hid_bpf_device_event(hid, type, data, size, interrupt);
- if (ret)
+ data = dispatch_hid_bpf_device_event(hid, type, data, &size, interrupt);
+ if (IS_ERR(data)) {
+ ret = PTR_ERR(data);
goto unlock;
+ }
if (!size) {
dbg_hid("empty report\n");
@@ -2158,6 +2160,10 @@ int hid_connect(struct hid_device *hdev, unsigned int connect_mask)
int len;
int ret;
+ ret = hid_bpf_connect_device(hdev);
+ if (ret)
+ return ret;
+
if (hdev->quirks & HID_QUIRK_HIDDEV_FORCE)
connect_mask |= (HID_CONNECT_HIDDEV_FORCE | HID_CONNECT_HIDDEV);
if (hdev->quirks & HID_QUIRK_HIDINPUT_FORCE)
@@ -2259,6 +2265,8 @@ void hid_disconnect(struct hid_device *hdev)
if (hdev->claimed & HID_CLAIMED_HIDRAW)
hidraw_disconnect(hdev);
hdev->claimed = 0;
+
+ hid_bpf_disconnect_device(hdev);
}
EXPORT_SYMBOL_GPL(hid_disconnect);
@@ -29,15 +29,32 @@ struct hid_device;
* a bigger index).
* @hid: the ``struct hid_device`` representing the device itself
* @report_type: used for ``hid_bpf_device_event()``
+ * @allocated_size: Allocated size of data.
+ *
+ * This is how much memory is available and can be requested
+ * by the HID program.
+ * Note that for ``HID_BPF_RDESC_FIXUP``, that memory is set to
+ * ``4096`` (4 KB)
* @size: Valid data in the data field.
*
* Programs can get the available valid size in data by fetching this field.
+ * Programs can also change this value by returning a positive number in the
+ * program.
+ * To discard the event, return a negative error code.
+ *
+ * ``size`` must always be less or equal than ``allocated_size`` (it is enforced
+ * once all BPF programs have been run).
+ * @retval: Return value of the previous program.
*/
struct hid_bpf_ctx {
__u32 index;
const struct hid_device *hid;
+ __u32 allocated_size;
enum hid_report_type report_type;
- __s32 size;
+ union {
+ __s32 retval;
+ __s32 size;
+ };
};
/* Following functions are tracepoints that BPF programs can attach to */
@@ -81,6 +98,12 @@ struct hid_bpf_prog_list {
/* stored in each device */
struct hid_bpf {
+ u8 *device_data; /* allocated when a bpf program of type
+ * SEC(f.../hid_bpf_device_event) has been attached
+ * to this HID device
+ */
+ u32 allocated_data;
+
struct hid_bpf_prog_list __rcu *progs[HID_BPF_PROG_TYPE_MAX]; /* attached BPF progs */
bool destroyed; /* prevents the assignment of any progs */
@@ -88,13 +111,17 @@ struct hid_bpf {
};
#ifdef CONFIG_HID_BPF
-int dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, u8 *data,
- u32 size, int interrupt);
+u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, u8 *data,
+ u32 *size, int interrupt);
+int hid_bpf_connect_device(struct hid_device *hdev);
+void hid_bpf_disconnect_device(struct hid_device *hdev);
void hid_bpf_destroy_device(struct hid_device *hid);
void hid_bpf_device_init(struct hid_device *hid);
#else /* CONFIG_HID_BPF */
-static inline int dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, u8 *data,
- u32 size, int interrupt) { return 0; }
+static inline u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type,
+ u8 *data, u32 *size, int interrupt) { return 0; }
+static inline int hid_bpf_connect_device(struct hid_device *hdev) { return 0; }
+static inline void hid_bpf_disconnect_device(struct hid_device *hdev) {}
static inline void hid_bpf_destroy_device(struct hid_device *hid) {}
static inline void hid_bpf_device_init(struct hid_device *hid) {}
#endif /* CONFIG_HID_BPF */