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@redhat.com
---
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; +}