[LTP] [PATCH 33/33] keyctl39: Negative tests for KEYCTL_WATCH_KEY

[Andrea Cervesato]

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

Add negative test cases for KEYCTL_WATCH_KEY verifying invalid
watch_id values, bogus key ids, missing View permission, invalid
file descriptors, non-watch-queue pipes, and removal of watches
on unwatched keys.

Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
---
 runtest/syscalls                            |   1 +
 testcases/kernel/syscalls/keyctl/.gitignore |   1 +
 testcases/kernel/syscalls/keyctl/keyctl39.c | 149 ++++++++++++++++++++++++++++
 3 files changed, 151 insertions(+)

diff --git a/runtest/syscalls b/runtest/syscalls
index e9d47b5c4..538449a81 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -756,6 +756,7 @@ keyctl35 keyctl35
 keyctl36 keyctl36
 keyctl37 keyctl37
 keyctl38 keyctl38
+keyctl39 keyctl39
 
 kcmp01 kcmp01
 kcmp02 kcmp02
diff --git a/testcases/kernel/syscalls/keyctl/.gitignore b/testcases/kernel/syscalls/keyctl/.gitignore
index c0a18dd77..8de3d46c2 100644
--- a/testcases/kernel/syscalls/keyctl/.gitignore
+++ b/testcases/kernel/syscalls/keyctl/.gitignore
@@ -36,3 +36,4 @@
 /keyctl36
 /keyctl37
 /keyctl38
+/keyctl39
diff --git a/testcases/kernel/syscalls/keyctl/keyctl39.c b/testcases/kernel/syscalls/keyctl/keyctl39.c
new file mode 100644
index 000000000..4a0cf5efb
--- /dev/null
+++ b/testcases/kernel/syscalls/keyctl/keyctl39.c
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2026 Andrea Cervesato <andrea.cervesato@suse.com>
+ */
+
+/*\
+ * Negative test cases for ``KEYCTL_WATCH_KEY`` of :manpage:`keyctl(2)`.
+ *
+ * [Algorithm]
+ *
+ * - verify ``KEYCTL_WATCH_KEY`` with ``watch_id < -1`` fails with ``EINVAL``
+ * - verify ``KEYCTL_WATCH_KEY`` with ``watch_id > 255`` fails with ``EINVAL``
+ * - verify ``KEYCTL_WATCH_KEY`` with bogus key id fails with ``ENOKEY``
+ * - verify ``KEYCTL_WATCH_KEY`` without View permission fails with ``EACCES``
+ * - verify ``KEYCTL_WATCH_KEY`` with invalid fd fails with ``EINVAL``
+ * - verify ``KEYCTL_WATCH_KEY`` with non-watch-queue fd fails with ``EINVAL``
+ * - verify ``KEYCTL_WATCH_KEY`` remove on unwatched key fails with ``EBADSLT``
+ */
+
+#define _GNU_SOURCE
+
+#include <unistd.h>
+#include "keyctl_common.h"
+#include "lapi/watch_queue.h"
+
+static key_serial_t key_valid;
+static key_serial_t key_no_view;
+static key_serial_t bogus_key = INT32_MAX;
+static int wqueue_pipefd[2] = {-1, -1};
+static int plain_pipefd[2] = {-1, -1};
+static int bad_fd = -1;
+
+static struct tcase {
+	key_serial_t *key;
+	int *fd;
+	int watch_id;
+	int exp_errno;
+	const char *desc;
+} tcases[] = {
+	{
+		.key = &key_valid,
+		.fd = &wqueue_pipefd[0],
+		.watch_id = -2,
+		.exp_errno = EINVAL,
+		.desc = "watch_id < -1",
+	},
+	{
+		.key = &key_valid,
+		.fd = &wqueue_pipefd[0],
+		.watch_id = 256,
+		.exp_errno = EINVAL,
+		.desc = "watch_id > 255",
+	},
+	{
+		.key = &bogus_key,
+		.fd = &wqueue_pipefd[0],
+		.watch_id = 1,
+		.exp_errno = ENOKEY,
+		.desc = "bogus key id",
+	},
+	{
+		.key = &key_no_view,
+		.fd = &wqueue_pipefd[0],
+		.watch_id = 1,
+		.exp_errno = EACCES,
+		.desc = "key without View permission",
+	},
+	{
+		.key = &key_valid,
+		.fd = &bad_fd,
+		.watch_id = 1,
+		.exp_errno = EINVAL,
+		.desc = "invalid fd",
+	},
+	{
+		.key = &key_valid,
+		.fd = &plain_pipefd[0],
+		.watch_id = 1,
+		.exp_errno = EINVAL,
+		.desc = "non-watch-queue fd",
+	},
+	{
+		.key = &key_valid,
+		.fd = &wqueue_pipefd[0],
+		.watch_id = -1,
+		.exp_errno = EBADSLT,
+		.desc = "remove watch on unwatched key",
+	},
+};
+
+static void setup(void)
+{
+	SAFE_KEYCTL(KEYCTL_JOIN_SESSION_KEYRING, 0, 0, 0, 0);
+
+	key_valid = new_user_key("ltpkeyctl39_valid", "data", 4,
+				 KEY_SPEC_PROCESS_KEYRING);
+
+	key_no_view = new_user_key("ltpkeyctl39_noview", "data", 4,
+				   KEY_SPEC_PROCESS_KEYRING);
+	SAFE_KEYCTL(KEYCTL_SETPERM, key_no_view, KEY_PERM_NO_VIEW, 0, 0);
+
+	TEST(pipe2(wqueue_pipefd, O_NOTIFICATION_PIPE));
+	if (TST_RET < 0) {
+		if (TST_ERR == ENOPKG)
+			tst_brk(TCONF | TTERRNO, "CONFIG_WATCH_QUEUE is not set");
+		if (TST_ERR == EINVAL)
+			tst_brk(TCONF | TTERRNO, "O_NOTIFICATION_PIPE is not supported");
+		tst_brk(TBROK | TTERRNO, "pipe2(O_NOTIFICATION_PIPE) failed");
+	}
+
+	SAFE_IOCTL(wqueue_pipefd[0], IOC_WATCH_QUEUE_SET_SIZE, 256);
+
+	SAFE_PIPE(plain_pipefd);
+}
+
+static void cleanup(void)
+{
+	if (wqueue_pipefd[0] != -1)
+		SAFE_CLOSE(wqueue_pipefd[0]);
+	if (wqueue_pipefd[1] != -1)
+		SAFE_CLOSE(wqueue_pipefd[1]);
+	if (plain_pipefd[0] != -1)
+		SAFE_CLOSE(plain_pipefd[0]);
+	if (plain_pipefd[1] != -1)
+		SAFE_CLOSE(plain_pipefd[1]);
+}
+
+static void run(unsigned int n)
+{
+	struct tcase *tc = &tcases[n];
+
+	TST_EXP_FAIL(keyctl(KEYCTL_WATCH_KEY, *tc->key, *tc->fd, tc->watch_id),
+		     tc->exp_errno,
+		     "%s", tc->desc);
+}
+
+static struct tst_test test = {
+	.setup = setup,
+	.cleanup = cleanup,
+	.test = run,
+	.tcnt = ARRAY_SIZE(tcases),
+	.min_kver = "5.8",
+	.needs_kconfigs = (const char *[]) {
+		"CONFIG_KEYS=y",
+		"CONFIG_KEY_NOTIFICATIONS=y",
+		"CONFIG_WATCH_QUEUE=y",
+		NULL
+	},
+};

-- 
2.51.0