selftests/bpf: Unprivileged tests for test_loader.c

Extends test_loader.c:test_loader__run_subtests() by allowing to
execute tests in unprivileged mode, similar to test_verifier.c.

Adds the following new attributes controlling test_loader behavior:

  __msg_unpriv
  __success_unpriv
  __failure_unpriv

* If any of these attributes is present the test would be loaded in
  unprivileged mode.
* If only "privileged" attributes are present the test would be loaded
  only in privileged mode.
* If both "privileged" and "unprivileged" attributes are present the
  test would be loaded in both modes.
* If test has to be executed in both modes, __msg(text) is specified
  and __msg_unpriv is not specified the behavior is the same as if
  __msg_unpriv(text) is specified.
* For test filtering purposes the name of the program loaded in
  unprivileged mode is derived from the usual program name by adding
  `@unpriv' suffix.

Also adds attribute '__description'. This attribute specifies text to
be used instead of a program name for display and filtering purposes.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230325025524.144043-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 26 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/unpriv_helpers.c b/tools/testing/selftests/bpf/unpriv_helpers.c
new file mode 100644
index 000000000000..2a6efbd0401e
--- /dev/null
+++ b/tools/testing/selftests/bpf/unpriv_helpers.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <error.h>
+#include <stdio.h>
+
+#include "unpriv_helpers.h"
+
+bool get_unpriv_disabled(void)
+{
+	bool disabled;
+	char buf[2];
+	FILE *fd;
+
+	fd = fopen("/proc/sys/" UNPRIV_SYSCTL, "r");
+	if (fd) {
+		disabled = (fgets(buf, 2, fd) == buf && atoi(buf));
+		fclose(fd);
+	} else {
+		perror("fopen /proc/sys/" UNPRIV_SYSCTL);
+		disabled = true;
+	}
+
+	return disabled;
+}