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
---
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/bpf/prog_tests/hid.c | 76 ++++++++++++++++++++ tools/testing/selftests/bpf/progs/hid.c | 53 ++++++++++++++ 2 files changed, 129 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/hid.c b/tools/testing/selftests/bpf/prog_tests/hid.c index 19172d3e0f44..9dc5f0038472 100644 --- a/tools/testing/selftests/bpf/prog_tests/hid.c +++ b/tools/testing/selftests/bpf/prog_tests/hid.c @@ -9,6 +9,7 @@ #include <dirent.h> #include <poll.h> #include <stdbool.h> +#include <linux/hidraw.h> #include <linux/uhid.h>
static unsigned char rdesc[] = { @@ -769,6 +770,73 @@ static int test_hid_user_raw_request_call(int uhid_fd, int dev_id) 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(void) +{ + struct hidraw_report_descriptor rpt_desc = {0}; + struct test_params params; + int err, uhid_fd, desc_size, hidraw_fd = -1, ret = -1; + int dev_id; + void *uhid_err; + pthread_t tid; + bool started = false; + + dev_id = rand() % 1024; + + uhid_fd = setup_uhid(dev_id); + if (!ASSERT_GE(uhid_fd, 0, "setup uhid")) + return uhid_fd; + + err = prep_test(dev_id, "hid_rdesc_fixup", ¶ms); + if (!ASSERT_EQ(err, 0, "prep_test(hid_rdesc_fixup)")) + goto cleanup; + + err = uhid_start_listener(&tid, uhid_fd); + ASSERT_OK(err, "uhid_start_listener"); + + started = true; + + hidraw_fd = params.hidraw_fd; + + /* check that hid_rdesc_fixup() was executed */ + ASSERT_EQ(params.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: + cleanup_test(¶ms); + + if (started) { + destroy(uhid_fd); + pthread_join(tid, &uhid_err); + err = (int)(long)uhid_err; + CHECK_FAIL(err); + } + + return ret; +} + void serial_test_hid_bpf(void) { int err, uhid_fd; @@ -799,6 +867,14 @@ void serial_test_hid_bpf(void) err = test_hid_user_raw_request_call(uhid_fd, dev_id); ASSERT_OK(err, "hid_user_raw_request");
+ /* + * this test should be run last because we disconnect/reconnect + * the device, meaning that it changes the overall uhid device + * and messes up with the thread that reads uhid events. + */ + err = test_rdesc_fixup(); + ASSERT_OK(err, "hid_rdesc_fixup"); + destroy(uhid_fd);
pthread_join(tid, &uhid_err); diff --git a/tools/testing/selftests/bpf/progs/hid.c b/tools/testing/selftests/bpf/progs/hid.c index 0be319c11575..863c37ddf5ff 100644 --- a/tools/testing/selftests/bpf/progs/hid.c +++ b/tools/testing/selftests/bpf/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; +}