security/landlock/ruleset.c - linux - Git at Google

 // 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.
  */

 #include <linux/bits.h>
 #include <linux/bug.h>
 #include <linux/cleanup.h>
 #include <linux/compiler_types.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/lockdep.h>
 #include <linux/mutex.h>
 #include <linux/overflow.h>
 #include <linux/rbtree.h>
 #include <linux/refcount.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <uapi/linux/landlock.h>

 #include "access.h"
 #include "id.h"
 #include "limits.h"
 #include "object.h"
 #include "ruleset.h"

 #include <trace/events/landlock.h>

 struct landlock_ruleset *
 landlock_create_ruleset(const access_mask_t fs_access_mask,
 			const access_mask_t net_access_mask,
 			const access_mask_t scope_mask)
 {
 	struct landlock_ruleset *new_ruleset;

 	/* Informs about useless ruleset. */
 	if (!fs_access_mask && !net_access_mask && !scope_mask)
 		return ERR_PTR(-ENOMSG);

 	new_ruleset = kzalloc_obj(*new_ruleset, GFP_KERNEL_ACCOUNT);
 	if (!new_ruleset)
 		return ERR_PTR(-ENOMEM);

 	refcount_set(&new_ruleset->usage, 1);
 	mutex_init(&new_ruleset->lock);
 	new_ruleset->rules.root_inode = RB_ROOT;

 #if IS_ENABLED(CONFIG_INET)
 	new_ruleset->rules.root_net_port = RB_ROOT;
 #endif /* IS_ENABLED(CONFIG_INET) */

 #ifdef CONFIG_TRACEPOINTS
 	new_ruleset->id = landlock_get_id_range(1);
 #endif /* CONFIG_TRACEPOINTS */

 	/* The caller must only pass supported access rights and scopes. */
 	if (fs_access_mask) {
 		const access_mask_t mask = fs_access_mask &
 					   LANDLOCK_MASK_ACCESS_FS;

 		WARN_ON_ONCE(fs_access_mask != mask);
 		new_ruleset->handled_masks.fs |= mask;
 	}
 	if (net_access_mask) {
 		const access_mask_t mask = net_access_mask &
 					   LANDLOCK_MASK_ACCESS_NET;

 		WARN_ON_ONCE(net_access_mask != mask);
 		new_ruleset->handled_masks.net |= mask;
 	}
 	if (scope_mask) {
 		const access_mask_t mask = scope_mask & LANDLOCK_MASK_SCOPE;

 		WARN_ON_ONCE(scope_mask != mask);
 		new_ruleset->handled_masks.scope |= mask;
 	}
 	return new_ruleset;
 }

 static void build_check_rule(void)
 {
 	const struct landlock_rule rule = {
 		.num_layers = ~0,
 	};

 	/*
 	 * Checks that .num_layers is large enough for at least
 	 * LANDLOCK_MAX_NUM_LAYERS layers.
 	 */
 	BUILD_BUG_ON(rule.num_layers < LANDLOCK_MAX_NUM_LAYERS);
 }

 static bool is_object_pointer(const enum landlock_key_type key_type)
 {
 	switch (key_type) {
 	case LANDLOCK_KEY_INODE:
 		return true;

 #if IS_ENABLED(CONFIG_INET)
 	case LANDLOCK_KEY_NET_PORT:
 		return false;
 #endif /* IS_ENABLED(CONFIG_INET) */

 	default:
 		WARN_ON_ONCE(1);
 		return false;
 	}
 }

 static struct landlock_rule *
 create_rule(const struct landlock_id id,
 	    const struct landlock_layer (*layers)[], const u32 num_layers,
 	    const struct landlock_layer *const new_layer)
 {
 	struct landlock_rule *new_rule;
 	u32 new_num_layers;

 	build_check_rule();
 	if (new_layer) {
 		/* Should already be checked by landlock_merge_ruleset(). */
 		if (WARN_ON_ONCE(num_layers >= LANDLOCK_MAX_NUM_LAYERS))
 			return ERR_PTR(-E2BIG);
 		new_num_layers = num_layers + 1;
 	} else {
 		new_num_layers = num_layers;
 	}
 	new_rule = kzalloc_flex(*new_rule, layers, new_num_layers,
 				GFP_KERNEL_ACCOUNT);
 	if (!new_rule)
 		return ERR_PTR(-ENOMEM);
 	RB_CLEAR_NODE(&new_rule->node);
 	if (is_object_pointer(id.type)) {
 		/* This should have been caught by landlock_store_rule(). */
 		WARN_ON_ONCE(!id.key.object);
 		landlock_get_object(id.key.object);
 	}

 	new_rule->key = id.key;
 	new_rule->num_layers = new_num_layers;
 	/* Copies the original layer stack. */
 	memcpy(new_rule->layers, layers,
 	       flex_array_size(new_rule, layers, num_layers));
 	if (new_layer)
 		/* Adds a copy of @new_layer on the layer stack. */
 		new_rule->layers[new_rule->num_layers - 1] = *new_layer;
 	return new_rule;
 }

 static void free_rule(struct landlock_rule *const rule,
 		      const enum landlock_key_type key_type)
 {
 	might_sleep();
 	if (!rule)
 		return;
 	if (is_object_pointer(key_type))
 		landlock_put_object(rule->key.object);
 	kfree(rule);
 }

 static void build_check_ruleset(void)
 {
 	const struct landlock_rules rules = {
 		.num_rules = ~0,
 	};

 	BUILD_BUG_ON(rules.num_rules < LANDLOCK_MAX_NUM_RULES);
 }

 /**
  * landlock_store_rule - Create and insert a rule into the rule storage
  *
  * @rules: The rule storage to be updated.  The caller is responsible for
  *         any required locking.  For rulesets, this means holding
  *         &landlock_ruleset.lock.  For domains under construction, no lock is
  *         needed because the domain is not yet visible to other tasks.
  * @id: The ID to build the new rule with.  The underlying kernel object, if
  *      any, must be held by the caller.
  * @layers: One or multiple layers to be copied into the new rule.
  * @num_layers: The number of @layers entries.
  *
  * When user space requests to add a new rule to a ruleset, @layers only
  * contains one entry and this entry is not assigned to any level.  In this
  * case, the new rule will extend @rules, similarly to a boolean OR between
  * access rights.
  *
  * When merging a ruleset in a domain, or copying a domain, @layers will be
  * added to @rules as new constraints, similarly to a boolean AND between access
  * rights.
  *
  * Return: 0 on success, -errno on failure.
  */
 int landlock_store_rule(struct landlock_rules *const rules,
 			const struct landlock_id id,
 			const struct landlock_layer (*layers)[],
 			const size_t num_layers)
 {
 	struct rb_node **walker_node;
 	struct rb_node *parent_node = NULL;
 	struct landlock_rule *new_rule;
 	struct rb_root *root;

 	might_sleep();
 	if (WARN_ON_ONCE(!layers))
 		return -ENOENT;

 	if (is_object_pointer(id.type) && WARN_ON_ONCE(!id.key.object))
 		return -ENOENT;

 	root = landlock_get_rule_root(rules, id.type);
 	if (IS_ERR(root))
 		return PTR_ERR(root);

 	walker_node = &root->rb_node;
 	while (*walker_node) {
 		struct landlock_rule *const this =
 			rb_entry(*walker_node, struct landlock_rule, node);

 		if (this->key.data != id.key.data) {
 			parent_node = *walker_node;
 			if (this->key.data < id.key.data)
 				walker_node = &((*walker_node)->rb_right);
 			else
 				walker_node = &((*walker_node)->rb_left);
 			continue;
 		}

 		/* Only a single-level layer should match an existing rule. */
 		if (WARN_ON_ONCE(num_layers != 1))
 			return -EINVAL;

 		/* If there is a matching rule, updates it. */
 		if ((*layers)[0].level == 0) {
 			/*
 			 * Extends access rights when the request comes from
 			 * landlock_add_rule(2), i.e. @rules is not a domain.
 			 */
 			if (WARN_ON_ONCE(this->num_layers != 1))
 				return -EINVAL;
 			if (WARN_ON_ONCE(this->layers[0].level != 0))
 				return -EINVAL;
 			this->layers[0].access |= (*layers)[0].access;
 			this->layers[0].flags.quiet |= (*layers)[0].flags.quiet;
 			return 0;
 		}

 		if (WARN_ON_ONCE(this->layers[0].level == 0))
 			return -EINVAL;

 		/*
 		 * Intersects access rights when it is a merge between a
 		 * ruleset and a domain.
 		 */
 		new_rule = create_rule(id, &this->layers, this->num_layers,
 				       &(*layers)[0]);
 		if (IS_ERR(new_rule))
 			return PTR_ERR(new_rule);
 		rb_replace_node(&this->node, &new_rule->node, root);
 		free_rule(this, id.type);
 		return 0;
 	}

 	/* There is no match for @id. */
 	build_check_ruleset();
 	if (rules->num_rules >= LANDLOCK_MAX_NUM_RULES)
 		return -E2BIG;
 	new_rule = create_rule(id, layers, num_layers, NULL);
 	if (IS_ERR(new_rule))
 		return PTR_ERR(new_rule);
 	rb_link_node(&new_rule->node, parent_node, walker_node);
 	rb_insert_color(&new_rule->node, root);
 	rules->num_rules++;
 	return 0;
 }

 static void build_check_layer(void)
 {
 	const struct landlock_layer layer = {
 		.level = ~0,
 		.access = ~0,
 	};

 	/*
 	 * Checks that .level and .access are large enough to contain their expected
 	 * maximum values.
 	 */
 	BUILD_BUG_ON(layer.level < LANDLOCK_MAX_NUM_LAYERS);
 	BUILD_BUG_ON(layer.access < LANDLOCK_MASK_ACCESS_FS);
 }

 /* @ruleset must be locked by the caller. */
 int landlock_insert_rule(struct landlock_ruleset *const ruleset,
 			 const struct landlock_id id,
 			 const access_mask_t access, const u32 flags)
 {
 	struct landlock_layer layers[] = { {
 		.access = access,
 		/*
 		 * When @level is zero, landlock_store_rule() extends @ruleset.
 		 */
 		.level = 0,
 		.flags = {
 			.quiet = !!(flags & LANDLOCK_ADD_RULE_QUIET),
 		},
 	} };
 	int err;

 	build_check_layer();
 	lockdep_assert_held(&ruleset->lock);
 	err = landlock_store_rule(&ruleset->rules, id, &layers,
 				  ARRAY_SIZE(layers));

 #ifdef CONFIG_TRACEPOINTS
 	if (!err)
 		ruleset->version++;
 #endif /* CONFIG_TRACEPOINTS */

 	return err;
 }

 void landlock_free_rules(struct landlock_rules *const rules)
 {
 	struct landlock_rule *freeme, *next;

 	might_sleep();
 	rbtree_postorder_for_each_entry_safe(freeme, next, &rules->root_inode,
 					     node)
 		free_rule(freeme, LANDLOCK_KEY_INODE);

 #if IS_ENABLED(CONFIG_INET)
 	rbtree_postorder_for_each_entry_safe(freeme, next,
 					     &rules->root_net_port, node)
 		free_rule(freeme, LANDLOCK_KEY_NET_PORT);
 #endif /* IS_ENABLED(CONFIG_INET) */
 }

 static void free_ruleset(struct landlock_ruleset *const ruleset)
 {
 	might_sleep();
 	trace_landlock_free_ruleset(ruleset);
 	landlock_free_rules(&ruleset->rules);
 	kfree(ruleset);
 }

 void landlock_put_ruleset(struct landlock_ruleset *const ruleset)
 {
 	might_sleep();
 	if (ruleset && refcount_dec_and_test(&ruleset->usage))
 		free_ruleset(ruleset);
 }
	// 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.
	*/

	#include <linux/bits.h>
	#include <linux/bug.h>
	#include <linux/cleanup.h>
	#include <linux/compiler_types.h>
	#include <linux/err.h>
	#include <linux/errno.h>
	#include <linux/kernel.h>
	#include <linux/lockdep.h>
	#include <linux/mutex.h>
	#include <linux/overflow.h>
	#include <linux/rbtree.h>
	#include <linux/refcount.h>
	#include <linux/slab.h>
	#include <linux/spinlock.h>
	#include <uapi/linux/landlock.h>

	#include "access.h"
	#include "id.h"
	#include "limits.h"
	#include "object.h"
	#include "ruleset.h"

	#include <trace/events/landlock.h>

	struct landlock_ruleset *
	landlock_create_ruleset(const access_mask_t fs_access_mask,
	const access_mask_t net_access_mask,
	const access_mask_t scope_mask)
	{
	struct landlock_ruleset *new_ruleset;

	/* Informs about useless ruleset. */
	if (!fs_access_mask && !net_access_mask && !scope_mask)
	return ERR_PTR(-ENOMSG);

	new_ruleset = kzalloc_obj(*new_ruleset, GFP_KERNEL_ACCOUNT);
	if (!new_ruleset)
	return ERR_PTR(-ENOMEM);

	refcount_set(&new_ruleset->usage, 1);
	mutex_init(&new_ruleset->lock);
	new_ruleset->rules.root_inode = RB_ROOT;

	#if IS_ENABLED(CONFIG_INET)
	new_ruleset->rules.root_net_port = RB_ROOT;
	#endif /* IS_ENABLED(CONFIG_INET) */

	#ifdef CONFIG_TRACEPOINTS
	new_ruleset->id = landlock_get_id_range(1);
	#endif /* CONFIG_TRACEPOINTS */

	/* The caller must only pass supported access rights and scopes. */
	if (fs_access_mask) {
	const access_mask_t mask = fs_access_mask &
	LANDLOCK_MASK_ACCESS_FS;

	WARN_ON_ONCE(fs_access_mask != mask);
	new_ruleset->handled_masks.fs \|= mask;
	}
	if (net_access_mask) {
	const access_mask_t mask = net_access_mask &
	LANDLOCK_MASK_ACCESS_NET;

	WARN_ON_ONCE(net_access_mask != mask);
	new_ruleset->handled_masks.net \|= mask;
	}
	if (scope_mask) {
	const access_mask_t mask = scope_mask & LANDLOCK_MASK_SCOPE;

	WARN_ON_ONCE(scope_mask != mask);
	new_ruleset->handled_masks.scope \|= mask;
	}
	return new_ruleset;
	}

	static void build_check_rule(void)
	{
	const struct landlock_rule rule = {
	.num_layers = ~0,
	};

	/*
	* Checks that .num_layers is large enough for at least
	* LANDLOCK_MAX_NUM_LAYERS layers.
	*/
	BUILD_BUG_ON(rule.num_layers < LANDLOCK_MAX_NUM_LAYERS);
	}

	static bool is_object_pointer(const enum landlock_key_type key_type)
	{
	switch (key_type) {
	case LANDLOCK_KEY_INODE:
	return true;

	#if IS_ENABLED(CONFIG_INET)
	case LANDLOCK_KEY_NET_PORT:
	return false;
	#endif /* IS_ENABLED(CONFIG_INET) */

	default:
	WARN_ON_ONCE(1);
	return false;
	}
	}

	static struct landlock_rule *
	create_rule(const struct landlock_id id,
	const struct landlock_layer (*layers)[], const u32 num_layers,
	const struct landlock_layer *const new_layer)
	{
	struct landlock_rule *new_rule;
	u32 new_num_layers;

	build_check_rule();
	if (new_layer) {
	/* Should already be checked by landlock_merge_ruleset(). */
	if (WARN_ON_ONCE(num_layers >= LANDLOCK_MAX_NUM_LAYERS))
	return ERR_PTR(-E2BIG);
	new_num_layers = num_layers + 1;
	} else {
	new_num_layers = num_layers;
	}
	new_rule = kzalloc_flex(*new_rule, layers, new_num_layers,
	GFP_KERNEL_ACCOUNT);
	if (!new_rule)
	return ERR_PTR(-ENOMEM);
	RB_CLEAR_NODE(&new_rule->node);
	if (is_object_pointer(id.type)) {
	/* This should have been caught by landlock_store_rule(). */
	WARN_ON_ONCE(!id.key.object);
	landlock_get_object(id.key.object);
	}

	new_rule->key = id.key;
	new_rule->num_layers = new_num_layers;
	/* Copies the original layer stack. */
	memcpy(new_rule->layers, layers,
	flex_array_size(new_rule, layers, num_layers));
	if (new_layer)
	/* Adds a copy of @new_layer on the layer stack. */
	new_rule->layers[new_rule->num_layers - 1] = *new_layer;
	return new_rule;
	}

	static void free_rule(struct landlock_rule *const rule,
	const enum landlock_key_type key_type)
	{
	might_sleep();
	if (!rule)
	return;
	if (is_object_pointer(key_type))
	landlock_put_object(rule->key.object);
	kfree(rule);
	}

	static void build_check_ruleset(void)
	{
	const struct landlock_rules rules = {
	.num_rules = ~0,
	};

	BUILD_BUG_ON(rules.num_rules < LANDLOCK_MAX_NUM_RULES);
	}

	/**
	* landlock_store_rule - Create and insert a rule into the rule storage
	*
	* @rules: The rule storage to be updated. The caller is responsible for
	* any required locking. For rulesets, this means holding
	* &landlock_ruleset.lock. For domains under construction, no lock is
	* needed because the domain is not yet visible to other tasks.
	* @id: The ID to build the new rule with. The underlying kernel object, if
	* any, must be held by the caller.
	* @layers: One or multiple layers to be copied into the new rule.
	* @num_layers: The number of @layers entries.
	*
	* When user space requests to add a new rule to a ruleset, @layers only
	* contains one entry and this entry is not assigned to any level. In this
	* case, the new rule will extend @rules, similarly to a boolean OR between
	* access rights.
	*
	* When merging a ruleset in a domain, or copying a domain, @layers will be
	* added to @rules as new constraints, similarly to a boolean AND between access
	* rights.
	*
	* Return: 0 on success, -errno on failure.
	*/
	int landlock_store_rule(struct landlock_rules *const rules,
	const struct landlock_id id,
	const struct landlock_layer (*layers)[],
	const size_t num_layers)
	{
	struct rb_node **walker_node;
	struct rb_node *parent_node = NULL;
	struct landlock_rule *new_rule;
	struct rb_root *root;

	might_sleep();
	if (WARN_ON_ONCE(!layers))
	return -ENOENT;

	if (is_object_pointer(id.type) && WARN_ON_ONCE(!id.key.object))
	return -ENOENT;

	root = landlock_get_rule_root(rules, id.type);
	if (IS_ERR(root))
	return PTR_ERR(root);

	walker_node = &root->rb_node;
	while (*walker_node) {
	struct landlock_rule *const this =
	rb_entry(*walker_node, struct landlock_rule, node);

	if (this->key.data != id.key.data) {
	parent_node = *walker_node;
	if (this->key.data < id.key.data)
	walker_node = &((*walker_node)->rb_right);
	else
	walker_node = &((*walker_node)->rb_left);
	continue;
	}

	/* Only a single-level layer should match an existing rule. */
	if (WARN_ON_ONCE(num_layers != 1))
	return -EINVAL;

	/* If there is a matching rule, updates it. */
	if ((*layers)[0].level == 0) {
	/*
	* Extends access rights when the request comes from
	* landlock_add_rule(2), i.e. @rules is not a domain.
	*/
	if (WARN_ON_ONCE(this->num_layers != 1))
	return -EINVAL;
	if (WARN_ON_ONCE(this->layers[0].level != 0))
	return -EINVAL;
	this->layers[0].access \|= (*layers)[0].access;
	this->layers[0].flags.quiet \|= (*layers)[0].flags.quiet;
	return 0;
	}

	if (WARN_ON_ONCE(this->layers[0].level == 0))
	return -EINVAL;

	/*
	* Intersects access rights when it is a merge between a
	* ruleset and a domain.
	*/
	new_rule = create_rule(id, &this->layers, this->num_layers,
	&(*layers)[0]);
	if (IS_ERR(new_rule))
	return PTR_ERR(new_rule);
	rb_replace_node(&this->node, &new_rule->node, root);
	free_rule(this, id.type);
	return 0;
	}

	/* There is no match for @id. */
	build_check_ruleset();
	if (rules->num_rules >= LANDLOCK_MAX_NUM_RULES)
	return -E2BIG;
	new_rule = create_rule(id, layers, num_layers, NULL);
	if (IS_ERR(new_rule))
	return PTR_ERR(new_rule);
	rb_link_node(&new_rule->node, parent_node, walker_node);
	rb_insert_color(&new_rule->node, root);
	rules->num_rules++;
	return 0;
	}

	static void build_check_layer(void)
	{
	const struct landlock_layer layer = {
	.level = ~0,
	.access = ~0,
	};

	/*
	* Checks that .level and .access are large enough to contain their expected
	* maximum values.
	*/
	BUILD_BUG_ON(layer.level < LANDLOCK_MAX_NUM_LAYERS);
	BUILD_BUG_ON(layer.access < LANDLOCK_MASK_ACCESS_FS);
	}

	/* @ruleset must be locked by the caller. */
	int landlock_insert_rule(struct landlock_ruleset *const ruleset,
	const struct landlock_id id,
	const access_mask_t access, const u32 flags)
	{
	struct landlock_layer layers[] = { {
	.access = access,
	/*
	* When @level is zero, landlock_store_rule() extends @ruleset.
	*/
	.level = 0,
	.flags = {
	.quiet = !!(flags & LANDLOCK_ADD_RULE_QUIET),
	},
	} };
	int err;

	build_check_layer();
	lockdep_assert_held(&ruleset->lock);
	err = landlock_store_rule(&ruleset->rules, id, &layers,
	ARRAY_SIZE(layers));

	#ifdef CONFIG_TRACEPOINTS
	if (!err)
	ruleset->version++;
	#endif /* CONFIG_TRACEPOINTS */

	return err;
	}

	void landlock_free_rules(struct landlock_rules *const rules)
	{
	struct landlock_rule freeme, next;

	might_sleep();
	rbtree_postorder_for_each_entry_safe(freeme, next, &rules->root_inode,
	node)
	free_rule(freeme, LANDLOCK_KEY_INODE);

	#if IS_ENABLED(CONFIG_INET)
	rbtree_postorder_for_each_entry_safe(freeme, next,
	&rules->root_net_port, node)
	free_rule(freeme, LANDLOCK_KEY_NET_PORT);
	#endif /* IS_ENABLED(CONFIG_INET) */
	}

	static void free_ruleset(struct landlock_ruleset *const ruleset)
	{
	might_sleep();
	trace_landlock_free_ruleset(ruleset);
	landlock_free_rules(&ruleset->rules);
	kfree(ruleset);
	}

	void landlock_put_ruleset(struct landlock_ruleset *const ruleset)
	{
	might_sleep();
	if (ruleset && refcount_dec_and_test(&ruleset->usage))
	free_ruleset(ruleset);
	}