diff --git a/security/landlock/.kunitconfig b/security/landlock/.kunitconfig
index 03e119466604..f9423f01ac5b 100644
--- a/security/landlock/.kunitconfig
+++ b/security/landlock/.kunitconfig
@@ -1,4 +1,6 @@
+CONFIG_AUDIT=y
 CONFIG_KUNIT=y
+CONFIG_NET=y
 CONFIG_SECURITY=y
 CONFIG_SECURITY_LANDLOCK=y
 CONFIG_SECURITY_LANDLOCK_KUNIT_TEST=y
diff --git a/security/landlock/Makefile b/security/landlock/Makefile
index b4538b7cf7d2..e1777abbc413 100644
--- a/security/landlock/Makefile
+++ b/security/landlock/Makefile
@@ -4,3 +4,5 @@ landlock-y := setup.o syscalls.o object.o ruleset.o \
 	cred.o task.o fs.o
 
 landlock-$(CONFIG_INET) += net.o
+
+landlock-$(CONFIG_AUDIT) += id.o
diff --git a/security/landlock/id.c b/security/landlock/id.c
new file mode 100644
index 000000000000..b3c353d6e0cd
--- /dev/null
+++ b/security/landlock/id.c
@@ -0,0 +1,249 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock LSM - Unique identification number generator
+ *
+ * Copyright © 2024-2025 Microsoft Corporation
+ */
+
+#include <kunit/test.h>
+#include <linux/atomic.h>
+#include <linux/random.h>
+#include <linux/spinlock.h>
+
+#include "common.h"
+#include "id.h"
+
+#define COUNTER_PRE_INIT 0
+
+static atomic64_t next_id = ATOMIC64_INIT(COUNTER_PRE_INIT);
+
+static void __init init_id(atomic64_t *const counter, const u32 random_32bits)
+{
+	u64 init;
+
+	/*
+	 * Ensures sure 64-bit values are always used by user space (or may
+	 * fail with -EOVERFLOW), and makes this testable.
+	 */
+	init = 1ULL << 32;
+
+	/*
+	 * Makes a large (2^32) boot-time value to limit ID collision in logs
+	 * from different boots, and to limit info leak about the number of
+	 * initially (relative to the reader) created elements (e.g. domains).
+	 */
+	init += random_32bits;
+
+	/* Sets first or ignores.  This will be the first ID. */
+	atomic64_cmpxchg(counter, COUNTER_PRE_INIT, init);
+}
+
+#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
+
+static void __init test_init_min(struct kunit *const test)
+{
+	atomic64_t counter = ATOMIC64_INIT(COUNTER_PRE_INIT);
+
+	init_id(&counter, 0);
+	KUNIT_EXPECT_EQ(test, atomic64_read(&counter), 1ULL + U32_MAX);
+}
+
+static void __init test_init_max(struct kunit *const test)
+{
+	atomic64_t counter = ATOMIC64_INIT(COUNTER_PRE_INIT);
+
+	init_id(&counter, ~0);
+	KUNIT_EXPECT_EQ(test, atomic64_read(&counter), 1 + (2ULL * U32_MAX));
+}
+
+static void __init test_init_once(struct kunit *const test)
+{
+	const u64 first_init = 1ULL + U32_MAX;
+	atomic64_t counter = ATOMIC64_INIT(COUNTER_PRE_INIT);
+
+	init_id(&counter, 0);
+	KUNIT_EXPECT_EQ(test, atomic64_read(&counter), first_init);
+
+	init_id(&counter, ~0);
+	KUNIT_EXPECT_EQ(test, atomic64_read(&counter), first_init);
+}
+
+#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
+
+void __init landlock_init_id(void)
+{
+	return init_id(&next_id, get_random_u32());
+}
+
+/*
+ * It's not worth it to try to hide the monotonic counter because it can still
+ * be inferred (with N counter ranges), and if we are allowed to read the inode
+ * number we should also be allowed to read the time creation anyway, and it
+ * can be handy to store and sort domain IDs for user space.
+ *
+ * Returns the value of next_id and increment it to let some space for the next
+ * one.
+ */
+static u64 get_id_range(size_t number_of_ids, atomic64_t *const counter,
+			u8 random_4bits)
+{
+	u64 id, step;
+
+	/*
+	 * We should return at least 1 ID, and we may need a set of consecutive
+	 * ones (e.g. to generate a set of inodes).
+	 */
+	if (WARN_ON_ONCE(number_of_ids <= 0))
+		number_of_ids = 1;
+
+	/*
+	 * Blurs the next ID guess with 1/16 ratio.  We get 2^(64 - 4) -
+	 * (2 * 2^32), so a bit less than 2^60 available IDs, which should be
+	 * much more than enough considering the number of CPU cycles required
+	 * to get a new ID (e.g. a full landlock_restrict_self() call), and the
+	 * cost of draining all available IDs during the system's uptime.
+	 */
+	random_4bits = random_4bits % (1 << 4);
+	step = number_of_ids + random_4bits;
+
+	/* It is safe to cast a signed atomic to an unsigned value. */
+	id = atomic64_fetch_add(step, counter);
+
+	/* Warns if landlock_init_id() was not called. */
+	WARN_ON_ONCE(id == COUNTER_PRE_INIT);
+	return id;
+}
+
+#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
+
+static void test_range1_rand0(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(1, &counter, 0), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 1);
+}
+
+static void test_range1_rand1(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(1, &counter, 1), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 2);
+}
+
+static void test_range1_rand16(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(1, &counter, 16), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 1);
+}
+
+static void test_range2_rand0(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(2, &counter, 0), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 2);
+}
+
+static void test_range2_rand1(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(2, &counter, 1), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 3);
+}
+
+static void test_range2_rand2(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(2, &counter, 2), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 4);
+}
+
+static void test_range2_rand16(struct kunit *const test)
+{
+	atomic64_t counter;
+	u64 init;
+
+	init = get_random_u32();
+	atomic64_set(&counter, init);
+	KUNIT_EXPECT_EQ(test, get_id_range(2, &counter, 16), init);
+	KUNIT_EXPECT_EQ(
+		test, get_id_range(get_random_u8(), &counter, get_random_u8()),
+		init + 2);
+}
+
+#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
+
+/**
+ * landlock_get_id_range - Get a range of unique IDs
+ *
+ * @number_of_ids: Number of IDs to hold.  Must be greater than one.
+ *
+ * Returns: The first ID in the range.
+ */
+u64 landlock_get_id_range(size_t number_of_ids)
+{
+	return get_id_range(number_of_ids, &next_id, get_random_u8());
+}
+
+#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST
+
+static struct kunit_case __refdata test_cases[] = {
+	/* clang-format off */
+	KUNIT_CASE(test_init_min),
+	KUNIT_CASE(test_init_max),
+	KUNIT_CASE(test_init_once),
+	KUNIT_CASE(test_range1_rand0),
+	KUNIT_CASE(test_range1_rand1),
+	KUNIT_CASE(test_range1_rand16),
+	KUNIT_CASE(test_range2_rand0),
+	KUNIT_CASE(test_range2_rand1),
+	KUNIT_CASE(test_range2_rand2),
+	KUNIT_CASE(test_range2_rand16),
+	{}
+	/* clang-format on */
+};
+
+static struct kunit_suite test_suite = {
+	.name = "landlock_id",
+	.test_cases = test_cases,
+};
+
+kunit_test_init_section_suite(test_suite);
+
+#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */
diff --git a/security/landlock/id.h b/security/landlock/id.h
new file mode 100644
index 000000000000..99f596123c19
--- /dev/null
+++ b/security/landlock/id.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock LSM - Unique identification number generator
+ *
+ * Copyright © 2024-2025 Microsoft Corporation
+ */
+
+#ifndef _SECURITY_LANDLOCK_ID_H
+#define _SECURITY_LANDLOCK_ID_H
+
+#ifdef CONFIG_AUDIT
+
+void __init landlock_init_id(void);
+
+u64 landlock_get_id_range(size_t number_of_ids);
+
+#else /* CONFIG_AUDIT */
+
+static inline void __init landlock_init_id(void)
+{
+}
+
+#endif /* CONFIG_AUDIT */
+
+#endif /* _SECURITY_LANDLOCK_ID_H */
diff --git a/security/landlock/setup.c b/security/landlock/setup.c
index 28519a45b11f..d297083efcb1 100644
--- a/security/landlock/setup.c
+++ b/security/landlock/setup.c
@@ -13,6 +13,7 @@
 #include "common.h"
 #include "cred.h"
 #include "fs.h"
+#include "id.h"
 #include "net.h"
 #include "setup.h"
 #include "task.h"
@@ -33,6 +34,7 @@ const struct lsm_id landlock_lsmid = {
 
 static int __init landlock_init(void)
 {
+	landlock_init_id();
 	landlock_add_cred_hooks();
 	landlock_add_task_hooks();
 	landlock_add_fs_hooks();
diff --git a/tools/testing/kunit/configs/all_tests.config b/tools/testing/kunit/configs/all_tests.config
index b3b00269a52a..ea1f824ae70f 100644
--- a/tools/testing/kunit/configs/all_tests.config
+++ b/tools/testing/kunit/configs/all_tests.config
@@ -44,6 +44,8 @@ CONFIG_DAMON_DBGFS_DEPRECATED=y
 
 CONFIG_REGMAP_BUILD=y
 
+CONFIG_AUDIT=y
+
 CONFIG_SECURITY=y
 CONFIG_SECURITY_APPARMOR=y
 CONFIG_SECURITY_LANDLOCK=y
