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Message-Id: <20240626-hid_hw_req_bpf-v2-8-cfd60fb6c79f@kernel.org>
Date: Wed, 26 Jun 2024 15:46:29 +0200
From: Benjamin Tissoires <bentiss@...nel.org>
To: Jiri Kosina <jikos@...nel.org>, Alexei Starovoitov <ast@...nel.org>,
Shuah Khan <shuah@...nel.org>, Jonathan Corbet <corbet@....net>
Cc: linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
bpf@...r.kernel.org, linux-kselftest@...r.kernel.org,
linux-doc@...r.kernel.org, Benjamin Tissoires <bentiss@...nel.org>
Subject: [PATCH HID v2 08/13] 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
Signed-off-by: Benjamin Tissoires <bentiss@...nel.org>
---
no changes in v2
---
drivers/hid/bpf/hid_bpf_dispatch.c | 5 ++
tools/testing/selftests/hid/hid_bpf.c | 102 ++++++++++++++++++++++++++++++++
tools/testing/selftests/hid/progs/hid.c | 58 ++++++++++++++++++
3 files changed, 165 insertions(+)
diff --git a/drivers/hid/bpf/hid_bpf_dispatch.c b/drivers/hid/bpf/hid_bpf_dispatch.c
index 49f261054418..0aab49a2b869 100644
--- a/drivers/hid/bpf/hid_bpf_dispatch.c
+++ b/drivers/hid/bpf/hid_bpf_dispatch.c
@@ -459,11 +459,16 @@ 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)
diff --git a/tools/testing/selftests/hid/hid_bpf.c b/tools/testing/selftests/hid/hid_bpf.c
index f97d56337d8a..40aedd1d9dc5 100644
--- a/tools/testing/selftests/hid/hid_bpf.c
+++ b/tools/testing/selftests/hid/hid_bpf.c
@@ -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,
diff --git a/tools/testing/selftests/hid/progs/hid.c b/tools/testing/selftests/hid/progs/hid.c
index 0ad452fcca58..1fa288b76cd5 100644
--- a/tools/testing/selftests/hid/progs/hid.c
+++ b/tools/testing/selftests/hid/progs/hid.c
@@ -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,
+};
--
2.44.0
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