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Thu, 28 May 2026 18:52:44 -0700 (PDT) From: Justin Suess To: gnoack3000@gmail.com, mic@digikod.net Cc: linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, Justin Suess Subject: [PATCH v8 10/10] landlock: Add KUnit tests for LANDLOCK_ADD_RULE_NO_INHERIT Date: Thu, 28 May 2026 21:52:09 -0400 Message-ID: <20260529015210.500291-11-utilityemal77@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260529015210.500291-1-utilityemal77@gmail.com> References: <20260529015210.500291-1-utilityemal77@gmail.com> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add the landlock_ruleset KUnit suite with five tests for the no_inherit handling in landlock_unmask_layers(): - test_unmask_no_inherit_propagates: a rule with no_inherit unmasks access and sets the no_inherit bit on the layer mask. - test_unmask_no_inherit_skip: a layer with no_inherit already set in the mask is skipped (no access removal). - test_unmask_no_inherit_both_set: when both rule and mask have no_inherit, the skip still happens and the bit stays set. - test_unmask_multilayer_no_inherit: no_inherit on one layer of a multi-layer rule only affects that layer. - test_unmask_no_inherit_sequential: applying a descendant rule (no_inherit) followed by an ancestor rule causes the ancestor to be skipped, modeling a path walk. Signed-off-by: Justin Suess --- Notes: v7..v8 changes: * Renamed patch from 'Implement KUnit test' to 'Add KUnit tests' (now plural). * Replaced the single test_unmask_layers_no_inherit() case with five focused tests aligned with the new per-layer no_inherit bit added to struct layer_mask in patch 6: - test_unmask_no_inherit_propagates - test_unmask_no_inherit_skip - test_unmask_no_inherit_both_set - test_unmask_multilayer_no_inherit - test_unmask_no_inherit_sequential * Added alloc_rule() and fill_masks() helpers to share setup across the new tests. security/landlock/ruleset.c | 182 ++++++++++++++++++++++++++++++++++++ 1 file changed, 182 insertions(+) diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c index c78e2b2d73ff..9f47d106aca3 100644 --- a/security/landlock/ruleset.c +++ b/security/landlock/ruleset.c @@ -6,6 +6,7 @@ * Copyright © 2018-2020 ANSSI */ +#include #include #include #include @@ -766,3 +767,184 @@ landlock_init_layer_masks(const struct landlock_ruleset *const domain, return handled_accesses; } + +#ifdef CONFIG_SECURITY_LANDLOCK_KUNIT_TEST + +/* + * Helper to allocate a rule with @num_layers layers and initialize + * its num_layers field. Caller must fill in individual layers. + */ +static struct landlock_rule *alloc_rule(struct kunit *test, u32 num_layers) +{ + struct landlock_rule *rule; + + rule = kzalloc(struct_size(rule, layers, num_layers), GFP_KERNEL); + KUNIT_ASSERT_NOT_NULL(test, rule); + rule->num_layers = num_layers; + return rule; +} + +/* + * Build a layer_masks with the first @num_layers layers' access set to + * @val, and all no_inherit flags cleared. Layers beyond @num_layers stay + * zeroed, matching what landlock_init_layer_masks() produces for a domain + * with that many layers. + */ +static void fill_masks(struct layer_masks *masks, access_mask_t val, + size_t num_layers) +{ + memset(masks, 0, sizeof(*masks)); + for (size_t i = 0; i < num_layers; i++) + masks->layers[i].access = val; +} + +/* Verify that a rule with no_inherit unmasks access and propagates the flag. */ +static void test_unmask_no_inherit_propagates(struct kunit *const test) +{ + struct landlock_rule *rule = alloc_rule(test, 1); + struct layer_masks masks; + const access_mask_t req = BIT_ULL(0) | BIT_ULL(1); + + rule->layers[0].level = 1; + rule->layers[0].access = BIT_ULL(0); + rule->layers[0].flags.no_inherit = true; + + fill_masks(&masks, req, 1); + landlock_unmask_layers(rule, &masks); + + /* access bit 0 should be cleared, bit 1 remains */ + KUNIT_EXPECT_EQ(test, (access_mask_t)masks.layers[0].access, + BIT_ULL(1)); + KUNIT_EXPECT_TRUE(test, masks.layers[0].no_inherit); + KUNIT_EXPECT_EQ(test, (access_mask_t)masks.layers[1].access, 0); + kfree(rule); +} + +/* Verify that a pre-set no_inherit in the mask causes the layer to be skipped. */ +static void test_unmask_no_inherit_skip(struct kunit *const test) +{ + struct landlock_rule *rule = alloc_rule(test, 1); + struct layer_masks masks; + const access_mask_t req = BIT_ULL(0); + + rule->layers[0].level = 1; + rule->layers[0].access = BIT_ULL(0); + + fill_masks(&masks, req, 1); + masks.layers[0].no_inherit = true; + landlock_unmask_layers(rule, &masks); + + /* bit 0 should NOT be cleared because layer was skipped */ + KUNIT_EXPECT_EQ(test, (access_mask_t)masks.layers[0].access, req); + KUNIT_EXPECT_TRUE(test, masks.layers[0].no_inherit); + kfree(rule); +} + +/* + * Verify that no_inherit on the rule is still set when the mask already + * has no_inherit (the skip prevents access removal but the flag propagates). + */ +static void test_unmask_no_inherit_both_set(struct kunit *const test) +{ + struct landlock_rule *rule = alloc_rule(test, 1); + struct layer_masks masks; + const access_mask_t req = BIT_ULL(0); + + rule->layers[0].level = 1; + rule->layers[0].access = BIT_ULL(0); + rule->layers[0].flags.no_inherit = true; + + fill_masks(&masks, req, 1); + masks.layers[0].no_inherit = true; + landlock_unmask_layers(rule, &masks); + + KUNIT_EXPECT_EQ(test, (access_mask_t)masks.layers[0].access, req); + KUNIT_EXPECT_TRUE(test, masks.layers[0].no_inherit); + kfree(rule); +} + +/* + * Verify that no_inherit on layer 1 of a multi-layer rule only affects + * layer 1; layer 2 still contributes normally. + */ +static void test_unmask_multilayer_no_inherit(struct kunit *const test) +{ + struct landlock_rule *rule = alloc_rule(test, 2); + struct layer_masks masks; + const access_mask_t req = BIT_ULL(0) | BIT_ULL(1); + + rule->layers[0].level = 1; + rule->layers[0].access = BIT_ULL(0); + rule->layers[0].flags.no_inherit = true; + + rule->layers[1].level = 2; + rule->layers[1].access = BIT_ULL(1); + + fill_masks(&masks, req, 2); + landlock_unmask_layers(rule, &masks); + + /* Layer 1: bit 0 cleared, no_inherit set */ + KUNIT_EXPECT_EQ(test, (access_mask_t)masks.layers[0].access, BIT_ULL(1)); + KUNIT_EXPECT_TRUE(test, masks.layers[0].no_inherit); + + /* Layer 2: bit 1 cleared, no_inherit not set */ + KUNIT_EXPECT_EQ(test, (access_mask_t)masks.layers[1].access, BIT_ULL(0)); + KUNIT_EXPECT_FALSE(test, masks.layers[1].no_inherit); + kfree(rule); +} + +/* + * Verify that when applying two rules sequentially (as happens during + * a path walk), no_inherit from the first rule prevents the second + * rule from contributing to that layer. + */ +static void test_unmask_no_inherit_sequential(struct kunit *const test) +{ + struct landlock_rule *rule1 = alloc_rule(test, 1); + struct landlock_rule *rule2 = alloc_rule(test, 1); + struct layer_masks masks; + const access_mask_t req = BIT_ULL(0) | BIT_ULL(1); + + /* Rule 1: no_inherit on layer 1, grants access bit 0 */ + rule1->layers[0].level = 1; + rule1->layers[0].access = BIT_ULL(0); + rule1->layers[0].flags.no_inherit = true; + + /* Rule 2: also on layer 1, grants access bit 1 (ancestor rule) */ + rule2->layers[0].level = 1; + rule2->layers[0].access = BIT_ULL(1); + + /* Apply rule1 first (descendant), then rule2 (ancestor) */ + fill_masks(&masks, req, 1); + landlock_unmask_layers(rule1, &masks); + landlock_unmask_layers(rule2, &masks); + + /* + * Rule2 should be skipped because rule1 set no_inherit. + * bit 0 cleared by rule1, bit 1 remains because rule2 skipped. + */ + KUNIT_EXPECT_EQ(test, (access_mask_t)masks.layers[0].access, BIT_ULL(1)); + KUNIT_EXPECT_TRUE(test, masks.layers[0].no_inherit); + kfree(rule1); + kfree(rule2); +} + +/* clang-format off */ +static struct kunit_case test_cases[] = { + KUNIT_CASE(test_unmask_no_inherit_propagates), + KUNIT_CASE(test_unmask_no_inherit_skip), + KUNIT_CASE(test_unmask_no_inherit_both_set), + KUNIT_CASE(test_unmask_multilayer_no_inherit), + KUNIT_CASE(test_unmask_no_inherit_sequential), + {} +}; +/* clang-format on */ + +static struct kunit_suite test_suite = { + .name = "landlock_ruleset", + .test_cases = test_cases, +}; + +kunit_test_suite(test_suite); + +#endif /* CONFIG_SECURITY_LANDLOCK_KUNIT_TEST */ -- 2.53.0