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 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;
+}
--
2.35.1
