Simple report descriptor override in HID: replace part of the report
descriptor from a static definition in the bpf kernel program.
Note that this test should be run last because we disconnect/reconnect
the device, meaning that it changes the overall uhid device.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
---
changes in v11:
- use the new facility from selftests/hid
no changes in v10
no changes in v9
no changes in v8
no changes in v7
no changes in v6
changes in v5:
- amended for the new API
not in v4
changes in v3:
- added a comment to mention that this test needs to be run last
changes in v2:
- split the series by bpf/libbpf/hid/selftests and samples
---
tools/testing/selftests/hid/hid_bpf.c | 32 +++++++++++++++
tools/testing/selftests/hid/progs/hid.c | 53 +++++++++++++++++++++++++
2 files changed, 85 insertions(+)
diff --git a/tools/testing/selftests/hid/hid_bpf.c b/tools/testing/selftests/hid/hid_bpf.c
index 7cd976b469b7..fc2ad0443803 100644
--- a/tools/testing/selftests/hid/hid_bpf.c
+++ b/tools/testing/selftests/hid/hid_bpf.c
@@ -741,6 +741,38 @@ TEST_F(hid_bpf, test_hid_user_raw_request_call)
ASSERT_EQ(args.data[1], 2);
}
+/*
+ * 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.
+ */
+TEST_F(hid_bpf, test_rdesc_fixup)
+{
+ struct hidraw_report_descriptor rpt_desc = {0};
+ const struct test_program progs[] = {
+ { .name = "hid_rdesc_fixup" },
+ };
+ int err, desc_size;
+
+ LOAD_PROGRAMS(progs);
+
+ /* check that hid_rdesc_fixup() was executed */
+ ASSERT_EQ(self->skel->data->callback2_check, 0x21);
+
+ /* read the exposed report descriptor from hidraw */
+ err = ioctl(self->hidraw_fd, HIDIOCGRDESCSIZE, &desc_size);
+ ASSERT_GE(err, 0) TH_LOG("error while reading HIDIOCGRDESCSIZE: %d", err);
+
+ /* ensure the new size of the rdesc is bigger than the old one */
+ ASSERT_GT(desc_size, sizeof(rdesc));
+
+ rpt_desc.size = desc_size;
+ err = ioctl(self->hidraw_fd, HIDIOCGRDESC, &rpt_desc);
+ ASSERT_GE(err, 0) TH_LOG("error while reading HIDIOCGRDESC: %d", err);
+
+ ASSERT_EQ(rpt_desc.value[4], 0x42);
+}
+
static int libbpf_print_fn(enum libbpf_print_level level,
const char *format, va_list args)
{
diff --git a/tools/testing/selftests/hid/progs/hid.c b/tools/testing/selftests/hid/progs/hid.c
index fde76f63927b..815ff94321c9 100644
--- a/tools/testing/selftests/hid/progs/hid.c
+++ b/tools/testing/selftests/hid/progs/hid.c
@@ -99,3 +99,56 @@ int hid_user_raw_request(struct hid_hw_request_syscall_args *args)
return 0;
}
+
+static const __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("?fmod_ret/hid_bpf_rdesc_fixup")
+int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hid_ctx)
+{
+ __u8 *data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 4096 /* size */);
+
+ if (!data)
+ return 0; /* EPERM check */
+
+ callback2_check = data[4];
+
+ /* insert rdesc at offset 73 */
+ __builtin_memcpy(&data[73], rdesc, sizeof(rdesc));
+
+ /* Change Usage Vendor globally */
+ data[4] = 0x42;
+
+ return sizeof(rdesc) + 73;
+}
--
2.36.1
