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 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 | 79 ++++++++++++++++++++ tools/testing/selftests/bpf/progs/hid.c | 54 +++++++++++++ 2 files changed, 133 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/hid.c b/tools/testing/selftests/bpf/prog_tests/hid.c index 9f9dd08d3232..8c8e17e7385f 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[] = { @@ -400,6 +401,76 @@ 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}; + void *uhid_err; + int ret = -1; + pthread_t tid; + + /* attach the program */ + hid_skel->links.hid_rdesc_fixup = + bpf_program__attach_hid(hid_skel->progs.hid_rdesc_fixup, sysfs_fd, 0); + if (!ASSERT_OK_PTR(hid_skel->links.hid_rdesc_fixup, + "attach_hid(hid_rdesc_fixup)")) + return PTR_ERR(hid_skel->links.hid_rdesc_fixup); + + err = uhid_start_listener(&tid, uhid_fd); + ASSERT_OK(err, "uhid_start_listener"); + + 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); + + pthread_join(tid, &uhid_err); + err = (int)(long)uhid_err; + CHECK_FAIL(err); + + return ret; +} + void serial_test_hid_bpf(void) { struct hid *hid_skel = NULL; @@ -434,6 +505,14 @@ void serial_test_hid_bpf(void) err = test_hid_raw_event(hid_skel, uhid_fd, sysfs_fd); ASSERT_OK(err, "hid");
+ /* + * 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(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 a28ba19ed933..c9ce0e36e7b9 100644 --- a/tools/testing/selftests/bpf/progs/hid.c +++ b/tools/testing/selftests/bpf/progs/hid.c @@ -23,3 +23,57 @@ 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) +{ + __u8 *data = bpf_hid_get_data(ctx, 0 /* offset */, 4096 /* size */); + + if (!data) + return 0; /* EPERM check */ + + callback2_check = data[4]; + + /* insert rdesc at offset 52 */ + __builtin_memcpy(&data[52], rdesc, sizeof(rdesc)); + ctx->size = sizeof(rdesc) + 52; + + /* Change Usage Vendor globally */ + data[4] = 0x42; + + return 0; +}