Commit 3ac83fcd authored by Benjamin Tissoires's avatar Benjamin Tissoires
Browse files

selftests/hid: add tests for hid_hw_output_report HID-BPF hooks 

We add 3 new tests:
- first, we make sure we can prevent the output_report to happen
- second, we make sure that we can detect that a given hidraw client
  was actually doing the request, and for that client only, call ourself
  hid_bpf_hw_output_report(), returning a custom value
- last, we ensure that we can not loop between hooks for
  hid_hw_output_report() and manual calls to hid_bpf_hw_output_report()
  from that same hook

Link: https://patch.msgid.link/20240626-hid_hw_req_bpf-v2-8-cfd60fb6c79f@kernel.org


Acked-by: default avatarJiri Kosina <jkosina@suse.com>
Signed-off-by: default avatarBenjamin Tissoires <bentiss@kernel.org>
parent 9286675a

drivers/hid/bpf/hid_bpf_dispatch.c

+5 −0
Original line number Diff line number Diff line
@@ -461,11 +461,16 @@ hid_bpf_hw_request(struct hid_bpf_ctx *ctx, __u8 *buf, size_t buf__sz, 
__bpf_kfunc int

hid_bpf_hw_output_report(struct hid_bpf_ctx *ctx, __u8 *buf, size_t buf__sz)

{

	struct hid_bpf_ctx_kern *ctx_kern;

	struct hid_device *hdev;

	size_t size = buf__sz;

	u8 *dma_data;

	int ret;



	ctx_kern = container_of(ctx, struct hid_bpf_ctx_kern, ctx);

	if (ctx_kern->from_bpf)

		return -EDEADLOCK;



	/* check arguments */

	ret = __hid_bpf_hw_check_params(ctx, buf, &size, HID_OUTPUT_REPORT);

	if (ret)

tools/testing/selftests/hid/hid_bpf.c

+102 −0
Original line number Diff line number Diff line
@@ -1028,6 +1028,108 @@ TEST_F(hid_bpf, test_hid_infinite_loop_raw_request_call) 
	ASSERT_EQ(err, 3) TH_LOG("unexpected returned size while reading HIDIOCGFEATURE: %d", err);

}



/*

 * Call hid_hw_output_report against the given uhid device,

 * check that the program is called and prevents the

 * call to uhid.

 */

TEST_F(hid_bpf, test_hid_filter_output_report_call)

{

	const struct test_program progs[] = {

		{ .name = "hid_test_filter_output_report" },

	};

	__u8 buf[10] = {0};

	int err;



	LOAD_PROGRAMS(progs);



	/* first check that we did not attach to device_event */



	/* inject one event */

	buf[0] = 1;

	buf[1] = 42;

	uhid_send_event(_metadata, self->uhid_fd, buf, 6);



	/* read the data from hidraw */

	memset(buf, 0, sizeof(buf));

	err = read(self->hidraw_fd, buf, sizeof(buf));

	ASSERT_EQ(err, 6) TH_LOG("read_hidraw");

	ASSERT_EQ(buf[0], 1);

	ASSERT_EQ(buf[1], 42);

	ASSERT_EQ(buf[2], 0) TH_LOG("leftovers_from_previous_test");



	/* now check that our program is preventing hid_hw_output_report() */



	buf[0] = 1; /* report ID */

	buf[1] = 2;

	buf[2] = 42;



	err = write(self->hidraw_fd, buf, 3);

	ASSERT_LT(err, 0) TH_LOG("unexpected success while sending hid_hw_output_report: %d", err);

	ASSERT_EQ(errno, 25) TH_LOG("unexpected error code while sending hid_hw_output_report: %d",

				    errno);



	/* remove our bpf program and check that we can now emit commands */



	/* detach the program */

	detach_bpf(self);



	self->hidraw_fd = open_hidraw(self->dev_id);

	ASSERT_GE(self->hidraw_fd, 0) TH_LOG("open_hidraw");



	err = write(self->hidraw_fd, buf, 3);

	ASSERT_GE(err, 0) TH_LOG("error while sending hid_hw_output_report: %d", err);

}



/*

 * Call hid_hw_output_report against the given uhid device,

 * check that the program is called and can issue the call

 * to uhid and transform the answer.

 */

TEST_F(hid_bpf, test_hid_change_output_report_call)

{

	const struct test_program progs[] = {

		{ .name = "hid_test_hidraw_output_report" },

	};

	__u8 buf[10] = {0};

	int err;



	LOAD_PROGRAMS(progs);



	/* emit hid_hw_output_report from hidraw */

	buf[0] = 1; /* report ID */

	buf[1] = 2;

	buf[2] = 42;



	err = write(self->hidraw_fd, buf, 10);

	ASSERT_EQ(err, 2) TH_LOG("unexpected returned size while sending hid_hw_output_report: %d",

				 err);

}



/*

 * Call hid_hw_output_report against the given uhid device,

 * check that the program is not making infinite loops.

 */

TEST_F(hid_bpf, test_hid_infinite_loop_output_report_call)

{

	const struct test_program progs[] = {

		{ .name = "hid_test_infinite_loop_output_report" },

	};

	__u8 buf[10] = {0};

	int err;



	LOAD_PROGRAMS(progs);



	/* emit hid_hw_output_report from hidraw */

	buf[0] = 1; /* report ID */

	buf[1] = 2;

	buf[2] = 42;



	err = write(self->hidraw_fd, buf, 8);

	ASSERT_EQ(err, 2) TH_LOG("unexpected returned size while sending hid_hw_output_report: %d",

				 err);

}



/*

 * Attach hid_insert{0,1,2} to the given uhid device,

 * retrieve and open the matching hidraw node,

tools/testing/selftests/hid/progs/hid.c

+58 −0
Original line number Diff line number Diff line
@@ -385,3 +385,61 @@ SEC(".struct_ops.link") 
struct hid_bpf_ops test_infinite_loop_raw_request = {

	.hid_hw_request = (void *)hid_test_infinite_loop_raw_request,

};



SEC("?struct_ops/hid_hw_output_report")

int BPF_PROG(hid_test_filter_output_report, struct hid_bpf_ctx *hctx, unsigned char reportnum,

	     enum hid_report_type rtype, enum hid_class_request reqtype, __u64 source)

{

	return -25;

}



SEC(".struct_ops.link")

struct hid_bpf_ops test_filter_output_report = {

	.hid_hw_output_report = (void *)hid_test_filter_output_report,

};



SEC("?struct_ops.s/hid_hw_output_report")

int BPF_PROG(hid_test_hidraw_output_report, struct hid_bpf_ctx *hctx, __u64 source)

{

	__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 3 /* size */);

	int ret;



	if (!data)

		return 0; /* EPERM check */



	/* check if the incoming request comes from our hidraw operation */

	if (source == (__u64)current_file)

		return hid_bpf_hw_output_report(hctx, data, 2);



	return 0;

}



SEC(".struct_ops.link")

struct hid_bpf_ops test_hidraw_output_report = {

	.hid_hw_output_report = (void *)hid_test_hidraw_output_report,

};



SEC("?struct_ops.s/hid_hw_output_report")

int BPF_PROG(hid_test_infinite_loop_output_report, struct hid_bpf_ctx *hctx, __u64 source)

{

	__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 3 /* size */);

	int ret;



	if (!data)

		return 0; /* EPERM check */



	/* always forward the request as-is to the device, hid-bpf should prevent

	 * infinite loops.

	 */



	ret = hid_bpf_hw_output_report(hctx, data, 2);

	if (ret == 2)

		return 2;



	return 0;

}



SEC(".struct_ops.link")

struct hid_bpf_ops test_infinite_loop_output_report = {

	.hid_hw_output_report = (void *)hid_test_infinite_loop_output_report,

};