[igt-dev] [PATCH i-g-t] tests/core_unauth_vs_render: new test for the relaxed DRM_AUTH handling

[Emil Velikov <emil.l.velikov@gmail.com>]

From: Emil Velikov <emil.velikov@collabora.com>

As the inline comment says, this test checks that the kernel allows
unauthenticated master with render capable, RENDER_ALLOW ioctls.

The kernel commit has extra details why.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
---
 tests/core_unauth_vs_render.c | 108 ++++++++++++++++++++++++++++++++++
 tests/meson.build             |   1 +
 2 files changed, 109 insertions(+)
 create mode 100644 tests/core_unauth_vs_render.c

diff --git a/tests/core_unauth_vs_render.c b/tests/core_unauth_vs_render.c
new file mode 100644
index 00000000..a7d70d77
--- /dev/null
+++ b/tests/core_unauth_vs_render.c
@@ -0,0 +1,108 @@
+/*
+ * Copyright 2018 Collabora, Ltd
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *   Emil Velikov <emil.velikov@collabora.com>
+ */
+
+/*
+ * Testcase: Render capable, unauthenticated master doesn't throw -EACCES for
+ * DRM_RENDER_ALLOW ioctls.
+ */
+
+#include "igt.h"
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <sys/time.h>
+#include <sys/poll.h>
+#include <sys/resource.h>
+#include "drm.h"
+
+IGT_TEST_DESCRIPTION("Call XXX from unauthenticated master doesn't return -EACCES.");
+
+static void test_unauth_vs_render(int master)
+{
+	int slave;
+	int prime_fd;
+	uint32_t handle;
+
+	/*
+	 * The second open() happens without CAP_SYS_ADMIN, thus it
+	 * will not be authenticated.
+	 */
+	slave = drm_open_driver(DRIVER_ANY); // XXX: relate to the master given?
+	igt_require(slave >= 0);
+
+	/* Issuing the following ioctl will fail, no doubt about it. */
+	igt_assert(drmPrimeFDToHandle(slave, prime_fd, &handle) < 0);
+
+	/*
+	 * Updated kernels allow render capable, unauthenticated
+	 * master to issue DRM_AUTH ioctls (like the above), as long as
+	 * they are annotated as DRM_RENDER_ALLOW.
+	 *
+	 * Older ones throw -EACCES.
+	 */
+	igt_assert(errno != EACCES);
+
+	close(slave);
+}
+
+/*
+ * By default IGT is executed as root.
+ * Thus we need to drop the priviladges so that the second open() results in a
+ * client which is not unauthenticated. Running as normal user cercumtains that.
+ *
+ * In both cases, we need to ensure the file permissions of the node are
+ * sufficient.
+ */
+#define RUN_AS_ROOT 1
+
+igt_main
+{
+	int master;
+
+	igt_fixture
+		master = drm_open_driver(DRIVER_ANY);
+
+	//igt_debugfs_dump(master, "clients");
+	igt_subtest("unauth-vs-render") {
+#if RUN_AS_ROOT
+		igt_fork(child, 1) {
+			igt_drop_root();
+#endif
+			test_unauth_vs_render(master);
+#if RUN_AS_ROOT
+		}
+		igt_waitchildren();
+#endif
+	}
+}
diff --git a/tests/meson.build b/tests/meson.build
index b8a6e61b..9bfd706b 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -1,5 +1,6 @@
 test_progs = [
 	'core_auth',
+	'core_unauth_vs_render',
 	'core_get_client_auth',
 	'core_getclient',
 	'core_getstats',
-- 
2.20.1

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