Merge tag 'landlock-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux

Pull landlock updates from Mickaël Salaün:
 "This brings two main changes to Landlock:

   - A signal scoping fix with a new interface for user space to know if
     it is compatible with the running kernel.

   - Audit support to give visibility on why access requests are denied,
     including the origin of the security policy, missing access rights,
     and description of object(s). This was designed to limit log spam
     as much as possible while still alerting about unexpected blocked
     access.

  With these changes come new and improved documentation, and a lot of
  new tests"

* tag 'landlock-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux: (36 commits)
  landlock: Add audit documentation
  selftests/landlock: Add audit tests for network
  selftests/landlock: Add audit tests for filesystem
  selftests/landlock: Add audit tests for abstract UNIX socket scoping
  selftests/landlock: Add audit tests for ptrace
  selftests/landlock: Test audit with restrict flags
  selftests/landlock: Add tests for audit flags and domain IDs
  selftests/landlock: Extend tests for landlock_restrict_self(2)'s flags
  selftests/landlock: Add test for invalid ruleset file descriptor
  samples/landlock: Enable users to log sandbox denials
  landlock: Add LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF
  landlock: Add LANDLOCK_RESTRICT_SELF_LOG_*_EXEC_* flags
  landlock: Log scoped denials
  landlock: Log TCP bind and connect denials
  landlock: Log truncate and IOCTL denials
  landlock: Factor out IOCTL hooks
  landlock: Log file-related denials
  landlock: Log mount-related denials
  landlock: Add AUDIT_LANDLOCK_DOMAIN and log domain status
  landlock: Add AUDIT_LANDLOCK_ACCESS and log ptrace denials
  ...

1 files changed, 12 insertions, 18 deletions

diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index bff4e40a3093..ce7940efea51 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -23,6 +23,8 @@
 #include <linux/workqueue.h>
 
 #include "access.h"
+#include "audit.h"
+#include "domain.h"
 #include "limits.h"
 #include "object.h"
 #include "ruleset.h"
@@ -307,22 +309,6 @@ int landlock_insert_rule(struct landlock_ruleset *const ruleset,
 	return insert_rule(ruleset, id, &layers, ARRAY_SIZE(layers));
 }
 
-static void get_hierarchy(struct landlock_hierarchy *const hierarchy)
-{
-	if (hierarchy)
-		refcount_inc(&hierarchy->usage);
-}
-
-static void put_hierarchy(struct landlock_hierarchy *hierarchy)
-{
-	while (hierarchy && refcount_dec_and_test(&hierarchy->usage)) {
-		const struct landlock_hierarchy *const freeme = hierarchy;
-
-		hierarchy = hierarchy->parent;
-		kfree(freeme);
-	}
-}
-
 static int merge_tree(struct landlock_ruleset *const dst,
 		      struct landlock_ruleset *const src,
 		      const enum landlock_key_type key_type)
@@ -477,7 +463,7 @@ static int inherit_ruleset(struct landlock_ruleset *const parent,
 		err = -EINVAL;
 		goto out_unlock;
 	}
-	get_hierarchy(parent->hierarchy);
+	landlock_get_hierarchy(parent->hierarchy);
 	child->hierarchy->parent = parent->hierarchy;
 
 out_unlock:
@@ -501,7 +487,7 @@ static void free_ruleset(struct landlock_ruleset *const ruleset)
 		free_rule(freeme, LANDLOCK_KEY_NET_PORT);
 #endif /* IS_ENABLED(CONFIG_INET) */
 
-	put_hierarchy(ruleset->hierarchy);
+	landlock_put_hierarchy(ruleset->hierarchy);
 	kfree(ruleset);
 }
 
@@ -520,6 +506,7 @@ static void free_ruleset_work(struct work_struct *const work)
 	free_ruleset(ruleset);
 }
 
+/* Only called by hook_cred_free(). */
 void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset)
 {
 	if (ruleset && refcount_dec_and_test(&ruleset->usage)) {
@@ -534,6 +521,9 @@ void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset)
  * @parent: Parent domain.
  * @ruleset: New ruleset to be merged.
  *
+ * The current task is requesting to be restricted.  The subjective credentials
+ * must not be in an overridden state. cf. landlock_init_hierarchy_log().
+ *
  * Returns the intersection of @parent and @ruleset, or returns @parent if
  * @ruleset is empty, or returns a duplicate of @ruleset if @parent is empty.
  */
@@ -579,6 +569,10 @@ landlock_merge_ruleset(struct landlock_ruleset *const parent,
 	if (err)
 		return ERR_PTR(err);
 
+	err = landlock_init_hierarchy_log(new_dom->hierarchy);
+	if (err)
+		return ERR_PTR(err);
+
 	return no_free_ptr(new_dom);
 }