[LTP] [PATCH v2 12/33] keyctl20: Test KEYCTL_MOVE displacement

[Andrea Cervesato <andrea.cervesato@suse.de>]

From: Andrea Cervesato <andrea.cervesato@suse.com>

Test KEYCTL_MOVE displacement behavior: verify moving a key without
KEYCTL_MOVE_EXCL into a destination holding a matching key displaces
the existing key.

Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
---
 runtest/syscalls                            |  1 +
 testcases/kernel/syscalls/keyctl/.gitignore |  1 +
 testcases/kernel/syscalls/keyctl/keyctl20.c | 62 +++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+)

diff --git a/runtest/syscalls b/runtest/syscalls
index 1935bee31..bfe4090a0 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -737,6 +737,7 @@ keyctl16 keyctl16
 keyctl17 keyctl17
 keyctl18 keyctl18
 keyctl19 keyctl19
+keyctl20 keyctl20
 
 kcmp01 kcmp01
 kcmp02 kcmp02
diff --git a/testcases/kernel/syscalls/keyctl/.gitignore b/testcases/kernel/syscalls/keyctl/.gitignore
index f32107923..acddfa79e 100644
--- a/testcases/kernel/syscalls/keyctl/.gitignore
+++ b/testcases/kernel/syscalls/keyctl/.gitignore
@@ -17,3 +17,4 @@
 /keyctl17
 /keyctl18
 /keyctl19
+/keyctl20
diff --git a/testcases/kernel/syscalls/keyctl/keyctl20.c b/testcases/kernel/syscalls/keyctl/keyctl20.c
new file mode 100644
index 000000000..6da36fe32
--- /dev/null
+++ b/testcases/kernel/syscalls/keyctl/keyctl20.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2026 Andrea Cervesato <andrea.cervesato@suse.com>
+ */
+
+/*\
+ * Test ``KEYCTL_MOVE`` displacement of :manpage:`keyctl(2)`.
+ *
+ * [Algorithm]
+ *
+ * - move a key without ``KEYCTL_MOVE_EXCL`` into a destination keyring that
+ *   already contains a matching key, verify it displaces the existing key
+ */
+
+#include "keyctl_common.h"
+
+#define RING_A_DESC	"ltpkeyctl20_a"
+#define RING_B_DESC	"ltpkeyctl20_b"
+#define KEY_DESC	"k"
+#define PAYLOAD		"payload"
+
+static key_serial_t ring_a, ring_b;
+static key_serial_t key_a, key_excl;
+
+static void setup(void)
+{
+	SAFE_KEYCTL(KEYCTL_JOIN_SESSION_KEYRING, 0, 0, 0, 0);
+
+	ring_a = new_ring(RING_A_DESC);
+	ring_b = new_ring(RING_B_DESC);
+
+	key_a = new_user_key(KEY_DESC, PAYLOAD, sizeof(PAYLOAD), ring_a);
+	key_excl = new_user_key(KEY_DESC, PAYLOAD, sizeof(PAYLOAD), ring_b);
+
+	/* Keep key_excl in session keyring so displacement does not destroy it */
+	SAFE_KEYCTL(KEYCTL_LINK, key_excl, KEY_SPEC_SESSION_KEYRING, 0, 0);
+}
+
+static void reset_state(void)
+{
+	SAFE_KEYCTL(KEYCTL_LINK, key_a, ring_a, 0, 0);
+	TEST(keyctl(KEYCTL_UNLINK, key_a, ring_b, 0, 0));
+	if (TST_RET == -1 && TST_ERR != ENOENT)
+		tst_brk(TBROK | TTERRNO, "failed to unlink key_a from ring_b");
+
+	SAFE_KEYCTL(KEYCTL_LINK, key_excl, ring_b, 0, 0);
+}
+
+static void run(void)
+{
+	reset_state();
+
+	TST_EXP_PASS(keyctl(KEYCTL_MOVE, key_a, ring_a, ring_b, 0));
+
+	TST_EXP_EQ_LI(search_ring(ring_b, "user", KEY_DESC), key_a);
+}
+
+static struct tst_test test = {
+	.setup = setup,
+	.test_all = run,
+	.min_kver = "5.3",
+};

-- 
2.51.0


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