linux-kernel - [PATCH] selftests: clone3: Avoid fragile struct poking

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Message-ID: <20240927150455.360843-1-bjorn@kernel.org>
Date: Fri, 27 Sep 2024 17:04:53 +0200
From: Björn Töpel <bjorn@...nel.org>
To: Adrian Reber <areber@...hat.com>,
	Christian Brauner <brauner@...nel.org>,
	Shuah Khan <shuah@...nel.org>,
	linux-kselftest@...r.kernel.org
Cc: Björn Töpel <bjorn@...osinc.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] selftests: clone3: Avoid fragile struct poking

From: Björn Töpel <bjorn@...osinc.com>

The struct libcap in the selftest, and the what libcap is actually
using doesn't match, so the test fail. Libcap internals have changed,
but the selftest hasn't.

Fix by avoid poking the libcap internals.

Signed-off-by: Björn Töpel <bjorn@...osinc.com>
---
 .../clone3/clone3_cap_checkpoint_restore.c      | 17 +++--------------
 1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c b/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c
index 31b56d625655..9e6ee8c5316e 100644
--- a/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c
+++ b/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c
@@ -89,14 +89,9 @@ 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 };
+	cap_value_t cap_values[] = { CAP_SETUID, CAP_SETGID, CAP_CHECKPOINT_RESTORE };
 	struct libcap *cap;
 	int ret = -1;
 	cap_t caps;
@@ -113,14 +108,8 @@ static int set_capability(void)
 		goto out;
 	}
 
-	cap_set_flag(caps, CAP_EFFECTIVE, 2, cap_values, CAP_SET);
-	cap_set_flag(caps, CAP_PERMITTED, 2, cap_values, CAP_SET);
-
-	cap = (struct libcap *) caps;
-
-	/* 40 -> CAP_CHECKPOINT_RESTORE */
-	cap->data[1].effective |= 1 << (40 - 32);
-	cap->data[1].permitted |= 1 << (40 - 32);
+	cap_set_flag(caps, CAP_EFFECTIVE, 3, cap_values, CAP_SET);
+	cap_set_flag(caps, CAP_PERMITTED, 3, cap_values, CAP_SET);
 
 	if (cap_set_proc(caps)) {
 		perror("cap_set_proc");

base-commit: 075dbe9f6e3c21596c5245826a4ee1f1c1676eb8
-- 
2.43.0