[LTP] [PATCH 16/33] keyctl24: Negative tests for KEYCTL_RESTRICT_KEYRING

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

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

Test error conditions of KEYCTL_RESTRICT_KEYRING using a parameterized
tcase table: invalid type/restriction combinations (EINVAL), non-keyrings
(ENOTDIR), unknown key type (ENOKEY), key type without lookup (ENOENT),
invalid restriction string (EINVAL), bogus key serial (ENOKEY), already
restricted (EEXIST), self-chain cycle (EDEADLK), and missing Setattr
(EACCES).

Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
---
 runtest/syscalls                            |   1 +
 testcases/kernel/syscalls/keyctl/.gitignore |   1 +
 testcases/kernel/syscalls/keyctl/keyctl24.c | 173 ++++++++++++++++++++++++++++
 3 files changed, 175 insertions(+)

diff --git a/runtest/syscalls b/runtest/syscalls
index f7c4830a9..be35e9f93 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -741,6 +741,7 @@ keyctl20 keyctl20
 keyctl21 keyctl21
 keyctl22 keyctl22
 keyctl23 keyctl23
+keyctl24 keyctl24
 
 kcmp01 kcmp01
 kcmp02 kcmp02
diff --git a/testcases/kernel/syscalls/keyctl/.gitignore b/testcases/kernel/syscalls/keyctl/.gitignore
index 803e4e94c..767ccf61a 100644
--- a/testcases/kernel/syscalls/keyctl/.gitignore
+++ b/testcases/kernel/syscalls/keyctl/.gitignore
@@ -21,3 +21,4 @@
 /keyctl21
 /keyctl22
 /keyctl23
+/keyctl24
diff --git a/testcases/kernel/syscalls/keyctl/keyctl24.c b/testcases/kernel/syscalls/keyctl/keyctl24.c
new file mode 100644
index 000000000..2ec78e720
--- /dev/null
+++ b/testcases/kernel/syscalls/keyctl/keyctl24.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2026 Andrea Cervesato <andrea.cervesato@suse.com>
+ */
+
+/*\
+ * Negative test cases for ``KEYCTL_RESTRICT_KEYRING`` of :manpage:`keyctl(2)`.
+ *
+ * [Algorithm]
+ *
+ * - restrict with ``NULL`` type and non-NULL restriction fails with ``EINVAL``
+ * - restrict with non-NULL type and ``NULL`` restriction fails with ``EINVAL``
+ * - restrict on a non-keyring key fails with ``ENOTDIR``
+ * - restrict with unknown key type fails with ``ENOKEY``
+ * - restrict with key type having no restriction lookup fails with ``ENOENT``
+ * - restrict with asymmetric type and invalid restriction string fails with
+ *   ``EINVAL``
+ * - restrict with asymmetric type and bogus key serial fails with ``ENOKEY``
+ * - restrict an already restricted keyring fails with ``EEXIST``
+ * - restrict with self-referencing key_or_keyring chain fails with ``EDEADLK``
+ * - restrict without Setattr permission fails with ``EACCES``
+ */
+
+#include <stdio.h>
+
+#include "keyctl_common.h"
+
+static key_serial_t ring_reject, ring_no_setattr;
+static key_serial_t user_key;
+static int asym_supported;
+
+/*
+ * A tcase with .id = NULL asks verify_negative() to allocate a fresh
+ * unrestricted keyring for the case and unlink it afterwards, so that a
+ * false-positive result cannot restrict a ring shared with later cases.
+ * .self_cycle asks for a "key_or_keyring:<fresh>:chain" restriction string
+ * pointing back at that fresh ring, needed for the EDEADLK check.
+ */
+static struct tcase {
+	key_serial_t *id;
+	int self_cycle;
+	const char *type;
+	const char *restriction;
+	int exp_errno;
+	int needs_asym;
+	const char *desc;
+} tcases[] = {
+	{
+		.restriction = "builtin_trusted",
+		.exp_errno = EINVAL,
+		.desc = "NULL type and non-NULL restriction",
+	},
+	{
+		.type = "asymmetric",
+		.exp_errno = EINVAL,
+		.desc = "non-NULL type and NULL restriction",
+	},
+	{
+		.id = &user_key,
+		.exp_errno = ENOTDIR,
+		.desc = "non-keyring key",
+	},
+	{
+		.type = "nosuchtype",
+		.restriction = "builtin_trusted",
+		.exp_errno = ENOKEY,
+		.desc = "unknown key type",
+	},
+	{
+		.type = "user",
+		.restriction = "builtin_trusted",
+		.exp_errno = ENOENT,
+		.desc = "key type having no lookup_restriction",
+	},
+	{
+		.type = "asymmetric",
+		.restriction = "bogus",
+		.exp_errno = EINVAL,
+		.needs_asym = 1,
+		.desc = "asymmetric with invalid restriction string",
+	},
+	{
+		.type = "asymmetric",
+		.restriction = "key_or_keyring:2147483647",
+		.exp_errno = ENOKEY,
+		.needs_asym = 1,
+		.desc = "asymmetric with bogus key serial",
+	},
+	{
+		.id = &ring_reject,
+		.exp_errno = EEXIST,
+		.desc = "already restricted keyring",
+	},
+	{
+		.self_cycle = 1,
+		.type = "asymmetric",
+		.exp_errno = EDEADLK,
+		.needs_asym = 1,
+		.desc = "self-referencing key_or_keyring chain",
+	},
+	{
+		.id = &ring_no_setattr,
+		.exp_errno = EACCES,
+		.desc = "keyring without Setattr permission",
+	},
+};
+
+static void setup(void)
+{
+	key_serial_t probe_ring;
+
+	SAFE_KEYCTL(KEYCTL_JOIN_SESSION_KEYRING, 0, 0, 0, 0);
+
+	ring_reject = new_ring("ltpkeyctl24_reject");
+	ring_no_setattr = new_ring("ltpkeyctl24_no_setattr");
+	SAFE_KEYCTL(KEYCTL_SETPERM, ring_no_setattr, KEY_PERM_NO_SETATTR, 0, 0);
+
+	/* Permanently restrict ring_reject with reject-all for EEXIST test */
+	SAFE_KEYCTL(KEYCTL_RESTRICT_KEYRING, ring_reject, 0, 0, 0);
+
+	user_key = new_user_key("k", "payload", 7, KEY_SPEC_PROCESS_KEYRING);
+
+	/* Probe asymmetric support on a throwaway ring so we cannot poison
+	 * any ring reused later by the tcase table.
+	 */
+	probe_ring = new_ring("ltpkeyctl24_probe");
+	TEST(keyctl(KEYCTL_RESTRICT_KEYRING, probe_ring,
+		    (unsigned long)"asymmetric", (unsigned long)"bogus", 0));
+	asym_supported = (TST_RET != -1 || TST_ERR != ENODEV);
+	keyctl(KEYCTL_UNLINK, probe_ring, KEY_SPEC_PROCESS_KEYRING, 0, 0);
+}
+
+static void verify_negative(unsigned int n)
+{
+	struct tcase *tc = &tcases[n];
+	key_serial_t id, fresh_ring = 0;
+	const char *restriction = tc->restriction;
+	char cycle_buf[64];
+
+	if (tc->needs_asym && !asym_supported) {
+		tst_res(TCONF, "asymmetric key type not supported");
+		return;
+	}
+
+	if (tc->id) {
+		id = *tc->id;
+	} else {
+		fresh_ring = new_ring("ltpkeyctl24_fresh");
+		id = fresh_ring;
+		if (tc->self_cycle) {
+			snprintf(cycle_buf, sizeof(cycle_buf),
+				 "key_or_keyring:%d:chain", fresh_ring);
+			restriction = cycle_buf;
+		}
+	}
+
+	TST_EXP_FAIL(keyctl(KEYCTL_RESTRICT_KEYRING, (unsigned long)id,
+			    (unsigned long)tc->type,
+			    (unsigned long)restriction, 0),
+		     tc->exp_errno,
+		     "KEYCTL_RESTRICT_KEYRING with %s", tc->desc);
+
+	if (fresh_ring)
+		keyctl(KEYCTL_UNLINK, fresh_ring, KEY_SPEC_PROCESS_KEYRING,
+		       0, 0);
+}
+
+static struct tst_test test = {
+	.setup = setup,
+	.test = verify_negative,
+	.tcnt = ARRAY_SIZE(tcases),
+	.min_kver = "4.12",
+};

-- 
2.51.0


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