1 files changed, 62 insertions, 3 deletions
diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst
index 2c1af0c930d4..13134bccdd39 100644
--- a/Documentation/userspace-api/landlock.rst
+++ b/Documentation/userspace-api/landlock.rst
@@ -445,9 +445,68 @@ system call:
         printf("Landlock supports LANDLOCK_ACCESS_FS_REFER.\n");
     }
 
-The following kernel interfaces are implicitly supported by the first ABI
-version.  Features only supported from a specific version are explicitly marked
-as such.
+All Landlock kernel interfaces are supported by the first ABI version unless
+explicitly noted in their documentation.
+
+Landlock errata
+---------------
+
+In addition to ABI versions, Landlock provides an errata mechanism to track
+fixes for issues that may affect backwards compatibility or require userspace
+awareness.  The errata bitmask can be queried using:
+
+.. code-block:: c
+
+    int errata;
+
+    errata = landlock_create_ruleset(NULL, 0, LANDLOCK_CREATE_RULESET_ERRATA);
+    if (errata < 0) {
+        /* Landlock not available or disabled */
+        return 0;
+    }
+
+The returned value is a bitmask where each bit represents a specific erratum.
+If bit N is set (``errata & (1 << (N - 1))``), then erratum N has been fixed
+in the running kernel.
+
+.. warning::
+
+   **Most applications should NOT check errata.** In 99.9% of cases, checking
+   errata is unnecessary, increases code complexity, and can potentially
+   decrease protection if misused.  For example, disabling the sandbox when an
+   erratum is not fixed could leave the system less secure than using
+   Landlock's best-effort protection.  When in doubt, ignore errata.
+
+.. kernel-doc:: security/landlock/errata/abi-4.h
+    :doc: erratum_1
+
+.. kernel-doc:: security/landlock/errata/abi-6.h
+    :doc: erratum_2
+
+.. kernel-doc:: security/landlock/errata/abi-1.h
+    :doc: erratum_3
+
+How to check for errata
+~~~~~~~~~~~~~~~~~~~~~~~
+
+If you determine that your application needs to check for specific errata,
+use this pattern:
+
+.. code-block:: c
+
+    int errata = landlock_create_ruleset(NULL, 0, LANDLOCK_CREATE_RULESET_ERRATA);
+    if (errata >= 0) {
+        /* Check for specific erratum (1-indexed) */
+        if (errata & (1 << (erratum_number - 1))) {
+            /* Erratum N is fixed in this kernel */
+        } else {
+            /* Erratum N is NOT fixed - consider implications for your use case */
+        }
+    }
+
+**Important:** Only check errata if your application specifically relies on
+behavior that changed due to the fix.  The fixes generally make Landlock less
+restrictive or more correct, not more restrictive.
 
 Kernel interface
 ================