1 files changed, 250 insertions, 0 deletions
diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
new file mode 100644
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--- /dev/null
+++ b/security/landlock/ruleset.h
@@ -0,0 +1,250 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock LSM - Ruleset management
+ *
+ * Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net>
+ * Copyright © 2018-2020 ANSSI
+ * Copyright © 2026 Cloudflare, Inc.
+ */
+
+#ifndef _SECURITY_LANDLOCK_RULESET_H
+#define _SECURITY_LANDLOCK_RULESET_H
+
+#include <linux/cleanup.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/rbtree.h>
+#include <linux/refcount.h>
+
+#include "access.h"
+#include "limits.h"
+#include "object.h"
+
+/**
+ * struct landlock_layer - Access rights for a given layer
+ */
+struct landlock_layer {
+	/**
+	 * @level: Position of this layer in the layer stack.  Starts from 1.
+	 */
+	u8 level;
+	/**
+	 * @flags: Bitfield for special flags attached to this rule.
+	 */
+	struct {
+		/**
+		 * @flags.quiet: Suppresses denial logs for the object covered by
+		 * this rule in this domain.  For filesystem rules, this inherits
+		 * down the file hierarchy.
+		 */
+		u8 quiet : 1;
+	} flags;
+	/**
+	 * @access: Bitfield of allowed actions on the kernel object.  They are
+	 * relative to the object type (e.g. %LANDLOCK_ACTION_FS_READ).
+	 */
+	access_mask_t access;
+};
+
+/**
+ * union landlock_key - Key of a ruleset's red-black tree
+ */
+union landlock_key {
+	/**
+	 * @object: Pointer to identify a kernel object (e.g. an inode).
+	 */
+	struct landlock_object *object;
+	/**
+	 * @data: Raw data to identify an arbitrary 32-bit value
+	 * (e.g. a TCP port).
+	 */
+	uintptr_t data;
+};
+
+/**
+ * enum landlock_key_type - Type of &union landlock_key
+ */
+enum landlock_key_type {
+	/**
+	 * @LANDLOCK_KEY_INODE: Type of &landlock_rules.root_inode's node keys.
+	 */
+	LANDLOCK_KEY_INODE = 1,
+	/**
+	 * @LANDLOCK_KEY_NET_PORT: Type of &landlock_rules.root_net_port's node
+	 * keys.
+	 */
+	LANDLOCK_KEY_NET_PORT,
+};
+
+/**
+ * struct landlock_id - Unique rule identifier for a ruleset
+ */
+struct landlock_id {
+	/**
+	 * @key: Identifies either a kernel object (e.g. an inode) or
+	 * a raw value (e.g. a TCP port).
+	 */
+	union landlock_key key;
+	/**
+	 * @type: Type of a landlock_ruleset's root tree.
+	 */
+	const enum landlock_key_type type;
+};
+
+/**
+ * struct landlock_rule - Access rights tied to an object
+ */
+struct landlock_rule {
+	/**
+	 * @node: Node in the ruleset's red-black tree.
+	 */
+	struct rb_node node;
+	/**
+	 * @key: A union to identify either a kernel object (e.g. an inode) or
+	 * a raw data value (e.g. a network socket port). This is used as a key
+	 * for this ruleset element.  The pointer is set once and never
+	 * modified.  It always points to an allocated object because each rule
+	 * increments the refcount of its object.
+	 */
+	union landlock_key key;
+	/**
+	 * @num_layers: Number of entries in @layers.
+	 */
+	u32 num_layers;
+	/**
+	 * @layers: Stack of layers, from the latest to the newest, implemented
+	 * as a flexible array member (FAM).
+	 */
+	struct landlock_layer layers[] __counted_by(num_layers);
+};
+
+/**
+ * struct landlock_rules - Red-black tree storage for Landlock rules
+ *
+ * This structure holds the rule trees shared by both rulesets and domains.
+ */
+struct landlock_rules {
+	/**
+	 * @root_inode: Root of a red-black tree containing &struct
+	 * landlock_rule nodes with inode object.  Immutable for domains.
+	 */
+	struct rb_root root_inode;
+
+#if IS_ENABLED(CONFIG_INET)
+	/**
+	 * @root_net_port: Root of a red-black tree containing &struct
+	 * landlock_rule nodes with network port.  Immutable for domains.
+	 */
+	struct rb_root root_net_port;
+#endif /* IS_ENABLED(CONFIG_INET) */
+
+	/**
+	 * @num_rules: Number of non-overlapping (i.e. not for the same object)
+	 * rules in this tree storage.
+	 */
+	u32 num_rules;
+};
+
+/**
+ * struct landlock_ruleset - Landlock ruleset
+ *
+ * This data structure must contain unique entries, be updatable, and quick to
+ * match an object.
+ */
+struct landlock_ruleset {
+	/**
+	 * @rules: Red-black tree storage for rules.
+	 */
+	struct landlock_rules rules;
+	/**
+	 * @lock: Protects against concurrent modifications of @rules, if @usage
+	 * is greater than zero.
+	 */
+	struct mutex lock;
+	/**
+	 * @usage: Number of file descriptors referencing this ruleset.
+	 */
+	refcount_t usage;
+
+#ifdef CONFIG_TRACEPOINTS
+	/**
+	 * @version: Counter incremented on each successful
+	 * landlock_add_rule(2), including when it only extends an existing
+	 * rule's access rights.  Used by tracepoints to correlate a domain with
+	 * the exact ruleset state it was created from.  Protected by @lock.
+	 */
+	u32 version;
+	/**
+	 * @id: Unique identifier for this ruleset, used for tracing.
+	 */
+	u64 id;
+#endif /* CONFIG_TRACEPOINTS */
+
+	/**
+	 * @quiet_masks: Stores the quiet flags for an unmerged ruleset.  For a
+	 * merged domain, this is stored in each layer's struct
+	 * landlock_hierarchy instead.
+	 */
+	struct access_masks quiet_masks;
+	/**
+	 * @handled_masks: Contains the subset of filesystem and network actions
+	 * that are handled by this ruleset.
+	 */
+	struct access_masks handled_masks;
+};
+
+struct landlock_ruleset *
+landlock_create_ruleset(const access_mask_t access_mask_fs,
+			const access_mask_t access_mask_net,
+			const access_mask_t scope_mask);
+
+void landlock_put_ruleset(struct landlock_ruleset *const ruleset);
+
+DEFINE_FREE(landlock_put_ruleset, struct landlock_ruleset *,
+	    if (!IS_ERR_OR_NULL(_T)) landlock_put_ruleset(_T))
+
+int landlock_insert_rule(struct landlock_ruleset *const ruleset,
+			 const struct landlock_id id,
+			 const access_mask_t access, const u32 flags);
+
+int landlock_store_rule(struct landlock_rules *const rules,
+			const struct landlock_id id,
+			const struct landlock_layer (*layers)[],
+			const size_t num_layers);
+
+void landlock_free_rules(struct landlock_rules *const rules);
+
+/**
+ * landlock_get_rule_root - Get the root of a rule tree by key type
+ *
+ * @rules: The rules storage to look up.
+ * @key_type: The type of key to select the tree for.
+ *
+ * Return: A pointer to the rb_root, or ERR_PTR(-EINVAL) on unknown type.
+ */
+static inline struct rb_root *
+landlock_get_rule_root(struct landlock_rules *const rules,
+		       const enum landlock_key_type key_type)
+{
+	switch (key_type) {
+	case LANDLOCK_KEY_INODE:
+		return &rules->root_inode;
+
+#if IS_ENABLED(CONFIG_INET)
+	case LANDLOCK_KEY_NET_PORT:
+		return &rules->root_net_port;
+#endif /* IS_ENABLED(CONFIG_INET) */
+
+	default:
+		WARN_ON_ONCE(1);
+		return ERR_PTR(-EINVAL);
+	}
+}
+
+static inline void landlock_get_ruleset(struct landlock_ruleset *const ruleset)
+{
+	if (ruleset)
+		refcount_inc(&ruleset->usage);
+}
+
+#endif /* _SECURITY_LANDLOCK_RULESET_H */