[PATCH bpf-next v2 05/28] selftests/bpf: add tests for the HID-bpf initial implementation

From: Benjamin Tissoires
Date: Fri Mar 04 2022 - 12:31:40 EST

The test is pretty basic:
- create a virtual uhid device that no userspace will like (to not mess
up the running system)
- attach a BPF prog to it
- open the matching hidraw node
- inject one event and check:
* that the BPF program can do something on the event stream
* can modify the event stream

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>

---

changes in v2:
- split the series by bpf/libbpf/hid/selftests and samples
---
tools/testing/selftests/bpf/prog_tests/hid.c | 335 +++++++++++++++++++
tools/testing/selftests/bpf/progs/hid.c | 20 ++
2 files changed, 355 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/hid.c
create mode 100644 tools/testing/selftests/bpf/progs/hid.c

diff --git a/tools/testing/selftests/bpf/prog_tests/hid.c b/tools/testing/selftests/bpf/prog_tests/hid.c
new file mode 100644
index 000000000000..ee495d5a8bd5
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/hid.c
@@ -0,0 +1,335 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Red Hat */
+#include <test_progs.h>
+#include <testing_helpers.h>
+#include "hid.skel.h"
+
+#include <fcntl.h>
+#include <fnmatch.h>
+#include <dirent.h>
+#include <poll.h>
+#include <stdbool.h>
+#include <linux/uhid.h>
+
+static unsigned char rdesc[] = {
+ 0x06, 0x00, 0xff, /* Usage Page (Vendor Defined Page 1) */
+ 0x09, 0x21, /* Usage (Vendor Usage 0x21) */
+ 0xa1, 0x01, /* COLLECTION (Application) */
+ 0x09, 0x01, /* Usage (Vendor Usage 0x01) */
+ 0xa1, 0x00, /* COLLECTION (Physical) */
+ 0x85, 0x01, /* REPORT_ID (1) */
+ 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) */
+ 0x81, 0x02, /* INPUT (Data,Var,Abs) */
+ 0x95, 0x01, /* REPORT_COUNT (1) */
+ 0x75, 0x05, /* REPORT_SIZE (5) */
+ 0x81, 0x01, /* INPUT (Cnst,Var,Abs) */
+ 0x05, 0x01, /* USAGE_PAGE (Generic Desktop) */
+ 0x09, 0x30, /* USAGE (X) */
+ 0x09, 0x31, /* USAGE (Y) */
+ 0x15, 0x81, /* LOGICAL_MINIMUM (-127) */
+ 0x25, 0x7f, /* LOGICAL_MAXIMUM (127) */
+ 0x75, 0x10, /* REPORT_SIZE (16) */
+ 0x95, 0x02, /* REPORT_COUNT (2) */
+ 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 */
+};
+
+static int uhid_write(int fd, const struct uhid_event *ev)
+{
+ ssize_t ret;
+
+ ret = write(fd, ev, sizeof(*ev));
+ if (ret < 0) {
+ fprintf(stderr, "Cannot write to uhid: %m\n");
+ return -errno;
+ } else if (ret != sizeof(*ev)) {
+ fprintf(stderr, "Wrong size written to uhid: %zd != %zu\n",
+ ret, sizeof(ev));
+ return -EFAULT;
+ } else {
+ return 0;
+ }
+}
+
+static int create(int fd, int rand_nb)
+{
+ struct uhid_event ev;
+ char buf[25];
+
+ sprintf(buf, "test-uhid-device-%d", rand_nb);
+
+ memset(&ev, 0, sizeof(ev));
+ ev.type = UHID_CREATE;
+ strcpy((char *)ev.u.create.name, buf);
+ ev.u.create.rd_data = rdesc;
+ ev.u.create.rd_size = sizeof(rdesc);
+ ev.u.create.bus = BUS_USB;
+ ev.u.create.vendor = 0x0001;
+ ev.u.create.product = 0x0a37;
+ ev.u.create.version = 0;
+ ev.u.create.country = 0;
+
+ sprintf(buf, "%d", rand_nb);
+ strcpy((char *)ev.u.create.phys, buf);
+
+ return uhid_write(fd, &ev);
+}
+
+static void destroy(int fd)
+{
+ struct uhid_event ev;
+
+ memset(&ev, 0, sizeof(ev));
+ ev.type = UHID_DESTROY;
+
+ uhid_write(fd, &ev);
+}
+
+static int send_event(int fd, u8 *buf, size_t size)
+{
+ struct uhid_event ev;
+
+ if (size > sizeof(ev.u.input.data))
+ return -E2BIG;
+
+ memset(&ev, 0, sizeof(ev));
+ ev.type = UHID_INPUT2;
+ ev.u.input2.size = size;
+
+ memcpy(ev.u.input2.data, buf, size);
+
+ return uhid_write(fd, &ev);
+}
+
+static int setup_uhid(int rand_nb)
+{
+ int fd;
+ const char *path = "/dev/uhid";
+ int ret;
+
+ fd = open(path, O_RDWR | O_CLOEXEC);
+ if (!ASSERT_GE(fd, 0, "open uhid-cdev"))
+ return -EPERM;
+
+ ret = create(fd, rand_nb);
+ if (!ASSERT_OK(ret, "create uhid device")) {
+ close(fd);
+ return -EPERM;
+ }
+
+ return fd;
+}
+
+static int get_sysfs_fd(int rand_nb)
+{
+ const char *workdir = "/sys/devices/virtual/misc/uhid";
+ const char *target = "0003:0001:0A37.*";
+ char uevent[1024];
+ char temp[512];
+ char phys[512];
+ DIR *d;
+ struct dirent *dir;
+ int fd, nread;
+ int found = -1;
+
+ /* it would be nice to be able to use nftw, but the no_alu32 target doesn't support it */
+
+ sprintf(phys, "PHYS=%d", rand_nb);
+
+ d = opendir(workdir);
+ if (d) {
+ while ((dir = readdir(d)) != NULL) {
+ if (fnmatch(target, dir->d_name, 0))
+ continue;
+
+ /* we found the correct VID/PID, now check for phys */
+ sprintf(uevent, "%s/%s/uevent", workdir, dir->d_name);
+ fd = open(uevent, O_RDONLY | O_NONBLOCK);
+ if (fd < 0)
+ continue;
+
+ nread = read(fd, temp, ARRAY_SIZE(temp));
+ if (nread > 0 && (strstr(temp, phys)) != NULL) {
+ found = fd;
+ break;
+ }
+
+ close(fd);
+ fd = 0;
+ }
+ closedir(d);
+ }
+
+ return found;
+}
+
+static int get_hidraw(struct bpf_link *link)
+{
+ struct bpf_link_info info = {0};
+ int prog_id, i;
+
+ /* retry 5 times in case the system is loaded */
+ for (i = 5; i > 0; i--) {
+ usleep(10);
+ prog_id = link_info_prog_id(link, &info);
+ if (!prog_id)
+ continue;
+ if (info.hid.hidraw_ino >= 0)
+ break;
+ }
+
+ if (!prog_id)
+ return -1;
+
+ return info.hid.hidraw_ino;
+}
+
+/*
+ * Attach hid_first_event to the given uhid device,
+ * retrieve and open the matching hidraw node,
+ * inject one event in the uhid device,
+ * check that the program sees it and can change the data
+ */
+static int test_hid_raw_event(struct hid *hid_skel, int uhid_fd, int sysfs_fd)
+{
+ int err, hidraw_ino, hidraw_fd = -1;
+ char hidraw_path[64] = {0};
+ u8 buf[10] = {0};
+ int ret = -1;
+
+ /* check that the program is correctly loaded */
+ ASSERT_EQ(hid_skel->data->callback_check, 52, "callback_check1");
+ ASSERT_EQ(hid_skel->data->callback2_check, 52, "callback2_check1");
+
+ /* attach the first program */
+ hid_skel->links.hid_first_event =
+ bpf_program__attach_hid(hid_skel->progs.hid_first_event, sysfs_fd);
+ if (!ASSERT_OK_PTR(hid_skel->links.hid_first_event,
+ "attach_hid(hid_first_event)"))
+ return PTR_ERR(hid_skel->links.hid_first_event);
+
+ hidraw_ino = get_hidraw(hid_skel->links.hid_first_event);
+ 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;
+
+ /* inject one event */
+ buf[0] = 1;
+ buf[1] = 42;
+ send_event(uhid_fd, buf, 6);
+
+ /* check that hid_first_event() was executed */
+ ASSERT_EQ(hid_skel->data->callback_check, 42, "callback_check1");
+
+ /* read the data from hidraw */
+ memset(buf, 0, sizeof(buf));
+ err = read(hidraw_fd, buf, sizeof(buf));
+ if (!ASSERT_EQ(err, 6, "read_hidraw"))
+ goto cleanup;
+
+ if (!ASSERT_EQ(buf[2], 47, "hid_first_event"))
+ goto cleanup;
+
+ /* inject another event */
+ buf[0] = 1;
+ buf[1] = 47;
+ send_event(uhid_fd, buf, 6);
+
+ /* check that hid_first_event() was executed */
+ ASSERT_EQ(hid_skel->data->callback_check, 47, "callback_check1");
+
+ /* read the data from hidraw */
+ memset(buf, 0, sizeof(buf));
+ err = read(hidraw_fd, buf, sizeof(buf));
+ if (!ASSERT_EQ(err, 6, "read_hidraw"))
+ goto cleanup;
+
+ if (!ASSERT_EQ(buf[2], 52, "hid_first_event"))
+ goto cleanup;
+
+ ret = 0;
+
+cleanup:
+ if (hidraw_fd >= 0)
+ close(hidraw_fd);
+
+ hid__detach(hid_skel);
+
+ return ret;
+}
+
+void serial_test_hid_bpf(void)
+{
+ struct hid *hid_skel = NULL;
+ int err, uhid_fd, sysfs_fd;
+ time_t t;
+ int rand_nb;
+
+ /* initialize random number generator */
+ srand((unsigned int)time(&t));
+
+ rand_nb = rand() % 1024;
+
+ uhid_fd = setup_uhid(rand_nb);
+ if (!ASSERT_GE(uhid_fd, 0, "setup uhid"))
+ return;
+
+ /* give a little bit of time for the device to appear */
+ /* TODO: check on uhid events */
+ usleep(1000);
+
+ /* locate the uevent file of the created device */
+ sysfs_fd = get_sysfs_fd(rand_nb);
+ if (!ASSERT_GE(sysfs_fd, 0, "locate sysfs uhid device"))
+ goto cleanup;
+
+ hid_skel = hid__open_and_load();
+ if (!ASSERT_OK_PTR(hid_skel, "hid_skel_load"))
+ goto cleanup;
+
+ /* start the tests! */
+ err = test_hid_raw_event(hid_skel, uhid_fd, sysfs_fd);
+ ASSERT_OK(err, "hid");
+
+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
new file mode 100644
index 000000000000..2201dd3b105d
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/hid.c
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Red hat */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <linux/bpf_hid.h>
+
+char _license[] SEC("license") = "GPL";
+
+__u64 callback_check = 52;
+__u64 callback2_check = 52;
+
+SEC("hid/device_event")
+int hid_first_event(struct hid_bpf_ctx *ctx)
+{
+ callback_check = ctx->data[1];
+
+ ctx->data[2] = ctx->data[1] + 5;
+
+ return 0;
+}
--
2.35.1