From patchwork Thu Feb 24 11:08:24 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Benjamin Tissoires X-Patchwork-Id: 545701 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1FEEDC4321E for ; Thu, 24 Feb 2022 11:09:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233800AbiBXLJy (ORCPT ); Thu, 24 Feb 2022 06:09:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230097AbiBXLJw (ORCPT ); Thu, 24 Feb 2022 06:09:52 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 28CF714FBDC for ; Thu, 24 Feb 2022 03:09:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645700960; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=N3cp1+AUEw8KVSjrTX4gG0oeNe61qbEHhfSUqcT0Biw=; b=NWoLE/CLzTSz5vSCf6tNRGRMg4Jd0eOM49RIK3lBG1mTiHFHvhXjbM8SX4NOiEPeOht3Zo 2k2UFvOjVCIa9ew38VCmPzTUTeCdE04VKWna3N7a7tMOHF/A8p5Kr/fxPvbvuxjTZJWIFM GaM3e5zxvCBqtEhLzGoBo2QHVV/cP8w= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-111-aqdgt50QOw2APlfdXy7NtA-1; Thu, 24 Feb 2022 06:09:16 -0500 X-MC-Unique: aqdgt50QOw2APlfdXy7NtA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 725E41006AA5; Thu, 24 Feb 2022 11:09:14 +0000 (UTC) Received: from plouf.redhat.com (unknown [10.39.194.109]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9C44C79A22; Thu, 24 Feb 2022 11:08:58 +0000 (UTC) From: Benjamin Tissoires To: Jiri Kosina , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Shuah Khan , Dave Marchevsky , Joe Stringer Cc: Tero Kristo , linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, Benjamin Tissoires Subject: [PATCH bpf-next v1 2/6] HID: bpf: allow to change the report descriptor from an eBPF program Date: Thu, 24 Feb 2022 12:08:24 +0100 Message-Id: <20220224110828.2168231-3-benjamin.tissoires@redhat.com> In-Reply-To: <20220224110828.2168231-1-benjamin.tissoires@redhat.com> References: <20220224110828.2168231-1-benjamin.tissoires@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org The report descriptor is the dictionary of the HID protocol specific to the given device. Changing it is a common habit in the HID world, and making that feature accessible from eBPF allows to fix devices without having to install a new kernel. Signed-off-by: Benjamin Tissoires --- drivers/hid/hid-bpf.c | 66 +++++++++++++++++++ drivers/hid/hid-core.c | 3 +- include/linux/bpf-hid.h | 4 ++ include/linux/hid.h | 6 ++ include/uapi/linux/bpf.h | 1 + include/uapi/linux/bpf_hid.h | 8 +++ kernel/bpf/hid.c | 5 ++ kernel/bpf/syscall.c | 2 + samples/bpf/hid_mouse_kern.c | 25 +++++++ tools/include/uapi/linux/bpf.h | 1 + tools/lib/bpf/libbpf.c | 1 + tools/testing/selftests/bpf/prog_tests/hid.c | 69 ++++++++++++++++++++ tools/testing/selftests/bpf/progs/hid.c | 48 ++++++++++++++ 13 files changed, 238 insertions(+), 1 deletion(-) diff --git a/drivers/hid/hid-bpf.c b/drivers/hid/hid-bpf.c index 6c8445820944..2d54c87cda1a 100644 --- a/drivers/hid/hid-bpf.c +++ b/drivers/hid/hid-bpf.c @@ -63,6 +63,14 @@ static struct hid_bpf_ctx *hid_bpf_allocate_ctx(struct hid_device *hdev) return ctx; } +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; @@ -84,6 +92,17 @@ 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) { @@ -91,6 +110,9 @@ 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 */ } @@ -110,6 +132,11 @@ static int hid_bpf_run_progs(struct hid_device *hdev, enum bpf_hid_attach_type t if (size > sizeof(ctx->u.device.data)) return -E2BIG; break; + case BPF_HID_ATTACH_RDESC_FIXUP: + event = HID_BPF_RDESC_FIXUP; + if (size > sizeof(ctx->u.rdesc.data)) + return -E2BIG; + break; default: return -EINVAL; } @@ -127,6 +154,10 @@ static int hid_bpf_run_progs(struct hid_device *hdev, enum bpf_hid_attach_type t memcpy(ctx->u.device.data, data, size); ctx->u.device.size = size; break; + case HID_BPF_RDESC_FIXUP: + memcpy(ctx->u.rdesc.data, data, size); + ctx->u.device.size = size; + break; default: /* do nothing */ } @@ -157,11 +188,46 @@ u8 *hid_bpf_raw_event(struct hid_device *hdev, u8 *data, int *size) return hdev->bpf.ctx->u.device.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 = hid_bpf_allocate_ctx(hdev); + 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->u.rdesc.size; + + if (!*size) { + rdesc = NULL; + goto unlock; + } + + rdesc = kmemdup(ctx->u.rdesc.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/bpf-hid.h b/include/linux/bpf-hid.h index 363fb6a4923f..377012a019da 100644 --- a/include/linux/bpf-hid.h +++ b/include/linux/bpf-hid.h @@ -14,6 +14,7 @@ struct hid_device; enum bpf_hid_attach_type { BPF_HID_ATTACH_INVALID = -1, BPF_HID_ATTACH_DEVICE_EVENT = 0, + BPF_HID_ATTACH_RDESC_FIXUP, MAX_BPF_HID_ATTACH_TYPE }; @@ -31,6 +32,8 @@ to_bpf_hid_attach_type(enum bpf_attach_type attach_type) switch (attach_type) { case BPF_HID_DEVICE_EVENT: return BPF_HID_ATTACH_DEVICE_EVENT; + case BPF_HID_RDESC_FIXUP: + return BPF_HID_ATTACH_RDESC_FIXUP; default: return BPF_HID_ATTACH_INVALID; } @@ -67,6 +70,7 @@ static inline bool bpf_hid_link_empty(struct bpf_hid *bpf, struct bpf_hid_hooks { struct hid_device *(*hdev_from_fd)(int fd); int (*link_attach)(struct hid_device *hdev, enum bpf_hid_attach_type type); + void (*link_attached)(struct hid_device *hdev, enum bpf_hid_attach_type type); void (*array_detached)(struct hid_device *hdev, enum bpf_hid_attach_type type); }; 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 diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 5978b92cacd3..a7a8d9cfcf24 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -999,6 +999,7 @@ enum bpf_attach_type { BPF_SK_REUSEPORT_SELECT_OR_MIGRATE, BPF_PERF_EVENT, BPF_HID_DEVICE_EVENT, + BPF_HID_RDESC_FIXUP, __MAX_BPF_ATTACH_TYPE }; diff --git a/include/uapi/linux/bpf_hid.h b/include/uapi/linux/bpf_hid.h index 243ac45a253f..c0801d7174c3 100644 --- a/include/uapi/linux/bpf_hid.h +++ b/include/uapi/linux/bpf_hid.h @@ -18,6 +18,7 @@ struct hid_device; enum hid_bpf_event { HID_BPF_UNDEF = 0, HID_BPF_DEVICE_EVENT, + HID_BPF_RDESC_FIXUP, }; /* type is HID_BPF_DEVICE_EVENT */ @@ -26,12 +27,19 @@ struct hid_bpf_ctx_device_event { unsigned long size; }; +/* type is HID_BPF_RDESC_FIXUP */ +struct hid_bpf_ctx_rdesc_fixup { + __u8 data[HID_BPF_MAX_BUFFER_SIZE]; + unsigned long size; +}; + struct hid_bpf_ctx { enum hid_bpf_event type; struct hid_device *hdev; union { struct hid_bpf_ctx_device_event device; + struct hid_bpf_ctx_rdesc_fixup rdesc; } u; }; diff --git a/kernel/bpf/hid.c b/kernel/bpf/hid.c index d3cb952bfc26..47cb0580b14a 100644 --- a/kernel/bpf/hid.c +++ b/kernel/bpf/hid.c @@ -315,6 +315,8 @@ static int bpf_hid_max_progs(enum bpf_hid_attach_type type) switch (type) { case BPF_HID_ATTACH_DEVICE_EVENT: return 64; + case BPF_HID_ATTACH_RDESC_FIXUP: + return 1; default: return 0; } @@ -355,6 +357,9 @@ static int bpf_hid_link_attach(struct hid_device *hdev, struct bpf_link *link, lockdep_is_held(&bpf_hid_mutex)); bpf_prog_array_free(run_array); + if (hid_hooks.link_attached) + hid_hooks.link_attached(hdev, type); + out_unlock: mutex_unlock(&bpf_hid_mutex); return err; diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 230ca6964a7e..62889cc71a02 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3191,6 +3191,7 @@ attach_type_to_prog_type(enum bpf_attach_type attach_type) case BPF_XDP: return BPF_PROG_TYPE_XDP; case BPF_HID_DEVICE_EVENT: + case BPF_HID_RDESC_FIXUP: return BPF_PROG_TYPE_HID; default: return BPF_PROG_TYPE_UNSPEC; @@ -3336,6 +3337,7 @@ static int bpf_prog_query(const union bpf_attr *attr, case BPF_SK_SKB_VERDICT: return sock_map_bpf_prog_query(attr, uattr); case BPF_HID_DEVICE_EVENT: + case BPF_HID_RDESC_FIXUP: return bpf_hid_prog_query(attr, uattr); default: return -EINVAL; diff --git a/samples/bpf/hid_mouse_kern.c b/samples/bpf/hid_mouse_kern.c index 83b0ab5a04d0..b4fac1c8bf6e 100644 --- a/samples/bpf/hid_mouse_kern.c +++ b/samples/bpf/hid_mouse_kern.c @@ -62,5 +62,30 @@ int hid_x_event(struct hid_bpf_ctx *ctx) return 0; } +SEC("hid/rdesc_fixup") +int hid_rdesc_fixup(struct hid_bpf_ctx *ctx) +{ + if (ctx->type != HID_BPF_RDESC_FIXUP) + return 0; + + bpf_printk("rdesc: %02x %02x %02x", + ctx->u.rdesc.data[0], + ctx->u.rdesc.data[1], + ctx->u.rdesc.data[2]); + bpf_printk(" %02x %02x %02x", + ctx->u.rdesc.data[3], + ctx->u.rdesc.data[4], + ctx->u.rdesc.data[5]); + bpf_printk(" %02x %02x %02x ...", + ctx->u.rdesc.data[6], + ctx->u.rdesc.data[7], + ctx->u.rdesc.data[8]); + + ctx->u.rdesc.data[39] = 0x31; + ctx->u.rdesc.data[41] = 0x30; + + return 0; +} + char _license[] SEC("license") = "GPL"; u32 _version SEC("version") = LINUX_VERSION_CODE; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 5978b92cacd3..a7a8d9cfcf24 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -999,6 +999,7 @@ enum bpf_attach_type { BPF_SK_REUSEPORT_SELECT_OR_MIGRATE, BPF_PERF_EVENT, BPF_HID_DEVICE_EVENT, + BPF_HID_RDESC_FIXUP, __MAX_BPF_ATTACH_TYPE }; diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index bad16e85032e..b7af873116fb 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -8677,6 +8677,7 @@ static const struct bpf_sec_def section_defs[] = { SEC_DEF("struct_ops+", STRUCT_OPS, 0, SEC_NONE), SEC_DEF("sk_lookup", SK_LOOKUP, BPF_SK_LOOKUP, SEC_ATTACHABLE | SEC_SLOPPY_PFX), SEC_DEF("hid/device_event", HID, BPF_HID_DEVICE_EVENT, SEC_ATTACHABLE_OPT | SEC_SLOPPY_PFX), + SEC_DEF("hid/rdesc_fixup", HID, BPF_HID_RDESC_FIXUP, SEC_ATTACHABLE_OPT | SEC_SLOPPY_PFX), }; #define MAX_TYPE_NAME_SIZE 32 diff --git a/tools/testing/selftests/bpf/prog_tests/hid.c b/tools/testing/selftests/bpf/prog_tests/hid.c index 692d78b9dc4a..dccbbcaa69e5 100644 --- a/tools/testing/selftests/bpf/prog_tests/hid.c +++ b/tools/testing/selftests/bpf/prog_tests/hid.c @@ -9,6 +9,7 @@ #include #include #include +#include #include static unsigned char rdesc[] = { @@ -279,6 +280,71 @@ static int test_hid_raw_event(struct hid *hid_skel, int uhid_fd, int sysfs_fd) return ret; } +/* + * Attach hid_rdesc_fixup to the given uhid device, + * retrieve and open the matching hidraw node, + * check that the hidraw report descriptor has been updated. + */ +static int test_rdesc_fixup(struct hid *hid_skel, int uhid_fd, int sysfs_fd) +{ + struct hidraw_report_descriptor rpt_desc = {0}; + int err, desc_size, hidraw_ino, hidraw_fd = -1; + char hidraw_path[64] = {0}; + int ret = -1; + + /* attach the program */ + hid_skel->links.hid_rdesc_fixup = + bpf_program__attach_hid(hid_skel->progs.hid_rdesc_fixup, sysfs_fd); + if (!ASSERT_OK_PTR(hid_skel->links.hid_rdesc_fixup, + "attach_hid(hid_rdesc_fixup)")) + return PTR_ERR(hid_skel->links.hid_rdesc_fixup); + + /* give a little bit of time for the device to appear */ + /* TODO: check on uhid events */ + usleep(1000); + + hidraw_ino = get_hidraw(hid_skel->links.hid_rdesc_fixup); + if (!ASSERT_GE(hidraw_ino, 0, "get_hidraw")) + goto cleanup; + + /* open hidraw node to check the other side of the pipe */ + sprintf(hidraw_path, "/dev/hidraw%d", hidraw_ino); + hidraw_fd = open(hidraw_path, O_RDWR | O_NONBLOCK); + + if (!ASSERT_GE(hidraw_fd, 0, "open_hidraw")) + goto cleanup; + + /* check that hid_rdesc_fixup() was executed */ + ASSERT_EQ(hid_skel->data->callback2_check, 0x21, "callback_check2"); + + /* read the exposed report descriptor from hidraw */ + err = ioctl(hidraw_fd, HIDIOCGRDESCSIZE, &desc_size); + if (!ASSERT_GE(err, 0, "HIDIOCGRDESCSIZE")) + goto cleanup; + + /* ensure the new size of the rdesc is bigger than the old one */ + if (!ASSERT_GT(desc_size, sizeof(rdesc), "new_rdesc_size")) + goto cleanup; + + rpt_desc.size = desc_size; + err = ioctl(hidraw_fd, HIDIOCGRDESC, &rpt_desc); + if (!ASSERT_GE(err, 0, "HIDIOCGRDESC")) + goto cleanup; + + if (!ASSERT_EQ(rpt_desc.value[4], 0x42, "hid_rdesc_fixup")) + goto cleanup; + + ret = 0; + +cleanup: + if (hidraw_fd >= 0) + close(hidraw_fd); + + hid__detach(hid_skel); + + return ret; +} + void serial_test_hid_bpf(void) { struct hid *hid_skel = NULL; @@ -312,6 +378,9 @@ void serial_test_hid_bpf(void) err = test_hid_raw_event(hid_skel, uhid_fd, sysfs_fd); ASSERT_OK(err, "hid"); + err = test_rdesc_fixup(hid_skel, uhid_fd, sysfs_fd); + ASSERT_OK(err, "hid_rdesc_fixup"); + cleanup: hid__destroy(hid_skel); destroy(uhid_fd); diff --git a/tools/testing/selftests/bpf/progs/hid.c b/tools/testing/selftests/bpf/progs/hid.c index f28bb6007875..f7a64c637782 100644 --- a/tools/testing/selftests/bpf/progs/hid.c +++ b/tools/testing/selftests/bpf/progs/hid.c @@ -18,3 +18,51 @@ int hid_first_event(struct hid_bpf_ctx *ctx) return 0; } + +static __u8 rdesc[] = { + 0x05, 0x01, /* USAGE_PAGE (Generic Desktop) */ + 0x09, 0x32, /* USAGE (Z) */ + 0x95, 0x01, /* REPORT_COUNT (1) */ + 0x81, 0x06, /* INPUT (Data,Var,Rel) */ + + 0x06, 0x00, 0xff, /* Usage Page (Vendor Defined Page 1) */ + 0x19, 0x01, /* USAGE_MINIMUM (1) */ + 0x29, 0x03, /* USAGE_MAXIMUM (3) */ + 0x15, 0x00, /* LOGICAL_MINIMUM (0) */ + 0x25, 0x01, /* LOGICAL_MAXIMUM (1) */ + 0x95, 0x03, /* REPORT_COUNT (3) */ + 0x75, 0x01, /* REPORT_SIZE (1) */ + 0x91, 0x02, /* Output (Data,Var,Abs) */ + 0x95, 0x01, /* REPORT_COUNT (1) */ + 0x75, 0x05, /* REPORT_SIZE (5) */ + 0x91, 0x01, /* Output (Cnst,Var,Abs) */ + + 0x06, 0x00, 0xff, /* Usage Page (Vendor Defined Page 1) */ + 0x19, 0x06, /* USAGE_MINIMUM (6) */ + 0x29, 0x08, /* USAGE_MAXIMUM (8) */ + 0x15, 0x00, /* LOGICAL_MINIMUM (0) */ + 0x25, 0x01, /* LOGICAL_MAXIMUM (1) */ + 0x95, 0x03, /* REPORT_COUNT (3) */ + 0x75, 0x01, /* REPORT_SIZE (1) */ + 0xb1, 0x02, /* Feature (Data,Var,Abs) */ + 0x95, 0x01, /* REPORT_COUNT (1) */ + 0x75, 0x05, /* REPORT_SIZE (5) */ + 0x91, 0x01, /* Output (Cnst,Var,Abs) */ + + 0xc0, /* END_COLLECTION */ + 0xc0, /* END_COLLECTION */ +}; + +SEC("hid/rdesc_fixup") +int hid_rdesc_fixup(struct hid_bpf_ctx *ctx) +{ + callback2_check = ctx->u.rdesc.data[4]; + + /* insert rdesc at offset 52 */ + __builtin_memcpy(&ctx->u.rdesc.data[52], rdesc, sizeof(rdesc)); + ctx->u.rdesc.size = sizeof(rdesc) + 52; + + ctx->u.rdesc.data[4] = 0x42; + + return 0; +}