[PATCH v2] selftests: clone3: Use the capget and capset syscall directly

[zhouyuhang]

From: zhouyuhang <zhouyuhang@xxxxxxxxxx>

The libcap commit aca076443591 ("Make cap_t operations thread safe.")
added a __u8 mutex at the beginning of the struct _cap_struct, it changes
the offset of the members in the structure that breaks the assumption
made in the "struct libcap" definition in clone3_cap_checkpoint_restore.c.
This will make the test fail. So use the capget and capset syscall
directly and remove the libcap library dependency like the
commit 663af70aabb7 ("bpf: selftests: Add helpers to directly use
the capget and capset syscall") does.

Signed-off-by: zhouyuhang <zhouyuhang@xxxxxxxxxx>
---
 tools/testing/selftests/clone3/Makefile       |  1 -
 .../clone3/clone3_cap_checkpoint_restore.c    | 53 ++++++++-----------
 .../selftests/clone3/clone3_cap_helpers.h     | 23 ++++++++
 3 files changed, 44 insertions(+), 33 deletions(-)
 create mode 100644 tools/testing/selftests/clone3/clone3_cap_helpers.h

diff --git a/tools/testing/selftests/clone3/Makefile b/tools/testing/selftests/clone3/Makefile
index 84832c369a2e..59d26e8da8d2 100644
--- a/tools/testing/selftests/clone3/Makefile
+++ b/tools/testing/selftests/clone3/Makefile
@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
 CFLAGS += -g -std=gnu99 $(KHDR_INCLUDES)
-LDLIBS += -lcap
 
 TEST_GEN_PROGS := clone3 clone3_clear_sighand clone3_set_tid \
 	clone3_cap_checkpoint_restore
diff --git a/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c b/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c
index 3c196fa86c99..242088eeec88 100644
--- a/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c
+++ b/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c
@@ -15,7 +15,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdbool.h>
-#include <sys/capability.h>
 #include <sys/prctl.h>
 #include <sys/syscall.h>
 #include <sys/types.h>
@@ -26,6 +25,7 @@
 
 #include "../kselftest_harness.h"
 #include "clone3_selftests.h"
+#include "clone3_cap_helpers.h"
 
 static void child_exit(int ret)
 {
@@ -87,47 +87,36 @@ static int test_clone3_set_tid(struct __test_metadata *_metadata,
 	return ret;
 }
 
-struct libcap {
-	struct __user_cap_header_struct hdr;
-	struct __user_cap_data_struct data[2];
-};
-
 static int set_capability(void)
 {
-	cap_value_t cap_values[] = { CAP_SETUID, CAP_SETGID };
-	struct libcap *cap;
-	int ret = -1;
-	cap_t caps;
-
-	caps = cap_get_proc();
-	if (!caps) {
-		perror("cap_get_proc");
+	struct __user_cap_data_struct data[2];
+	struct __user_cap_header_struct hdr = {
+		.version = _LINUX_CAPABILITY_VERSION_3,
+	};
+	__u32 cap0 = 1 << CAP_SETUID | 1 << CAP_SETGID;
+	__u32 cap1 = 1 << (CAP_CHECKPOINT_RESTORE - 32);
+	int ret;
+
+	ret = capget(&hdr, data);
+	if (ret) {
+		perror("capget");
 		return -1;
 	}
 
 	/* Drop all capabilities */
-	if (cap_clear(caps)) {
-		perror("cap_clear");
-		goto out;
-	}
+	memset(&data, 0, sizeof(data));
 
-	cap_set_flag(caps, CAP_EFFECTIVE, 2, cap_values, CAP_SET);
-	cap_set_flag(caps, CAP_PERMITTED, 2, cap_values, CAP_SET);
+	data[0].effective |= cap0;
+	data[0].permitted |= cap0;
 
-	cap = (struct libcap *) caps;
+	data[1].effective |= cap1;
+	data[1].permitted |= cap1;
 
-	/* 40 -> CAP_CHECKPOINT_RESTORE */
-	cap->data[1].effective |= 1 << (40 - 32);
-	cap->data[1].permitted |= 1 << (40 - 32);
-
-	if (cap_set_proc(caps)) {
-		perror("cap_set_proc");
-		goto out;
+	ret = capset(&hdr, data);
+	if (ret) {
+		perror("capset");
+		return -1;
 	}
-	ret = 0;
-out:
-	if (cap_free(caps))
-		perror("cap_free");
 	return ret;
 }
 
diff --git a/tools/testing/selftests/clone3/clone3_cap_helpers.h b/tools/testing/selftests/clone3/clone3_cap_helpers.h
new file mode 100644
index 000000000000..3fa59ef68fb8
--- /dev/null
+++ b/tools/testing/selftests/clone3/clone3_cap_helpers.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __CLONE3_CAP_HELPERS_H
+#define __CLONE3_CAP_HELPERS_H
+
+#include <linux/capability.h>
+
+/*
+ * Compatible with older version
+ * header file without defined
+ * CAP_CHECKPOINT_RESTORE.
+ */
+#ifndef CAP_CHECKPOINT_RESTORE
+#define CAP_CHECKPOINT_RESTORE 40
+#endif
+
+/*
+ * Removed the libcap library dependency.
+ * So declare them here directly.
+ */
+int capget(cap_user_header_t header, cap_user_data_t data);
+int capset(cap_user_header_t header, const cap_user_data_t data);
+
+#endif
-- 
2.27.0