Make use of BPF_HID_ATTACH_RDESC_FIXUP so we can trigger an rdesc fixup in the bpf world.
Whenever the program gets attached/detached, the device is reconnected meaning that userspace will see it disappearing and reappearing with the new report descriptor.
Signed-off-by: Benjamin Tissoires benjamin.tissoires@redhat.com
---
changes in v2: - split the series by bpf/libbpf/hid/selftests and samples --- drivers/hid/hid-bpf.c | 60 ++++++++++++++++++++++++++++++++++++++++++ drivers/hid/hid-core.c | 3 ++- include/linux/hid.h | 6 +++++ 3 files changed, 68 insertions(+), 1 deletion(-)
diff --git a/drivers/hid/hid-bpf.c b/drivers/hid/hid-bpf.c index 8120e598de9f..510e24f4307c 100644 --- a/drivers/hid/hid-bpf.c +++ b/drivers/hid/hid-bpf.c @@ -50,6 +50,14 @@ static struct hid_device *hid_bpf_fd_to_hdev(int fd) return hdev; }
+static int hid_reconnect(struct hid_device *hdev) +{ + if (!test_and_set_bit(ffs(HID_STAT_REPROBED), &hdev->status)) + return device_reprobe(&hdev->dev); + + return 0; +} + static int hid_bpf_link_attach(struct hid_device *hdev, enum bpf_hid_attach_type type) { int err = 0; @@ -71,6 +79,17 @@ static int hid_bpf_link_attach(struct hid_device *hdev, enum bpf_hid_attach_type return err; }
+static void hid_bpf_link_attached(struct hid_device *hdev, enum bpf_hid_attach_type type) +{ + switch (type) { + case BPF_HID_ATTACH_RDESC_FIXUP: + hid_reconnect(hdev); + break; + default: + /* do nothing */ + } +} + static void hid_bpf_array_detached(struct hid_device *hdev, enum bpf_hid_attach_type type) { switch (type) { @@ -78,6 +97,9 @@ static void hid_bpf_array_detached(struct hid_device *hdev, enum bpf_hid_attach_ kfree(hdev->bpf.ctx); hdev->bpf.ctx = NULL; break; + case BPF_HID_ATTACH_RDESC_FIXUP: + hid_reconnect(hdev); + break; default: /* do nothing */ } @@ -98,6 +120,9 @@ static int hid_bpf_run_progs(struct hid_device *hdev, enum bpf_hid_attach_type t case BPF_HID_ATTACH_DEVICE_EVENT: event = HID_BPF_DEVICE_EVENT; break; + case BPF_HID_ATTACH_RDESC_FIXUP: + event = HID_BPF_RDESC_FIXUP; + break; default: return -EINVAL; } @@ -138,11 +163,46 @@ u8 *hid_bpf_raw_event(struct hid_device *hdev, u8 *data, int *size) return hdev->bpf.ctx->data; }
+u8 *hid_bpf_report_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size) +{ + struct hid_bpf_ctx *ctx = NULL; + int ret; + + if (bpf_hid_link_empty(&hdev->bpf, BPF_HID_ATTACH_RDESC_FIXUP)) + goto ignore_bpf; + + ctx = bpf_hid_allocate_ctx(hdev, HID_MAX_DESCRIPTOR_SIZE); + if (IS_ERR(ctx)) + goto ignore_bpf; + + ret = hid_bpf_run_progs(hdev, BPF_HID_ATTACH_RDESC_FIXUP, ctx, rdesc, *size); + if (ret) + goto ignore_bpf; + + *size = ctx->size; + + if (!*size) { + rdesc = NULL; + goto unlock; + } + + rdesc = kmemdup(ctx->data, *size, GFP_KERNEL); + + unlock: + kfree(ctx); + return rdesc; + + ignore_bpf: + kfree(ctx); + return kmemdup(rdesc, *size, GFP_KERNEL); +} + int __init hid_bpf_module_init(void) { struct bpf_hid_hooks hooks = { .hdev_from_fd = hid_bpf_fd_to_hdev, .link_attach = hid_bpf_link_attach, + .link_attached = hid_bpf_link_attached, .array_detached = hid_bpf_array_detached, };
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index a80bffe6ce4a..0eb8189faaee 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1213,7 +1213,8 @@ int hid_open_report(struct hid_device *device) return -ENODEV; size = device->dev_rsize;
- buf = kmemdup(start, size, GFP_KERNEL); + /* hid_bpf_report_fixup() ensures we work on a copy of rdesc */ + buf = hid_bpf_report_fixup(device, start, &size); if (buf == NULL) return -ENOMEM;
diff --git a/include/linux/hid.h b/include/linux/hid.h index 8fd79011f461..66d949d10b78 100644 --- a/include/linux/hid.h +++ b/include/linux/hid.h @@ -1213,10 +1213,16 @@ do { \
#ifdef CONFIG_BPF u8 *hid_bpf_raw_event(struct hid_device *hdev, u8 *rd, int *size); +u8 *hid_bpf_report_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size); int hid_bpf_module_init(void); void hid_bpf_module_exit(void); #else static inline u8 *hid_bpf_raw_event(struct hid_device *hdev, u8 *rd, int *size) { return rd; } +static inline u8 *hid_bpf_report_fixup(struct hid_device *hdev, u8 *rdesc, + unsigned int *size) +{ + return kmemdup(rdesc, *size, GFP_KERNEL); +} static inline int hid_bpf_module_init(void) { return 0; } static inline void hid_bpf_module_exit(void) {} #endif