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Message-ID: <20220516152038.39594-3-konstantin.meskhidze@huawei.com>
Date: Mon, 16 May 2022 23:20:25 +0800
From: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
To: <mic@...ikod.net>
CC: <willemdebruijn.kernel@...il.com>,
<linux-security-module@...r.kernel.org>, <netdev@...r.kernel.org>,
<netfilter-devel@...r.kernel.org>, <yusongping@...wei.com>,
<anton.sirazetdinov@...wei.com>
Subject: [PATCH v5 02/15] landlock: landlock_find/insert_rule refactoring
A new object union added to support a socket port
rule type. To support it landlock_insert_rule() and
landlock_find_rule() were refactored. Now adding
or searching a rule in a ruleset depends on a
rule_type argument provided in refactored
functions mentioned above.
Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
---
Changes since v3:
* Split commit.
* Refactoring landlock_insert_rule and landlock_find_rule functions.
* Rename new_ruleset->root_inode.
Changes since v4:
* Refactoring insert_rule() and create_rule() functions by deleting
rule_type from their arguments list, it helps to reduce useless code.
---
security/landlock/fs.c | 8 ++-
security/landlock/ruleset.c | 129 +++++++++++++++++++++++++-----------
security/landlock/ruleset.h | 32 +++++----
3 files changed, 113 insertions(+), 56 deletions(-)
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 8eea52e5a3a4..5de24d4dd74c 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -173,7 +173,8 @@ int landlock_append_fs_rule(struct landlock_ruleset *const ruleset,
if (IS_ERR(object))
return PTR_ERR(object);
mutex_lock(&ruleset->lock);
- err = landlock_insert_rule(ruleset, object, access_rights);
+ err = landlock_insert_rule(ruleset, object, 0, access_rights,
+ LANDLOCK_RULE_PATH_BENEATH);
mutex_unlock(&ruleset->lock);
/*
* No need to check for an error because landlock_insert_rule()
@@ -203,8 +204,9 @@ find_rule(const struct landlock_ruleset *const domain,
inode = d_backing_inode(dentry);
rcu_read_lock();
- rule = landlock_find_rule(
- domain, rcu_dereference(landlock_inode(inode)->object));
+ rule = landlock_find_rule(domain,
+ (uintptr_t)rcu_dereference(landlock_inode(inode)->object),
+ LANDLOCK_RULE_PATH_BENEATH);
rcu_read_unlock();
return rule;
}
diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index b8917f6a8050..f079a2a320f1 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -35,7 +35,7 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
return ERR_PTR(-ENOMEM);
refcount_set(&new_ruleset->usage, 1);
mutex_init(&new_ruleset->lock);
- new_ruleset->root = RB_ROOT;
+ new_ruleset->root_inode = RB_ROOT;
new_ruleset->num_layers = num_layers;
/*
* hierarchy = NULL
@@ -69,10 +69,12 @@ static void build_check_rule(void)
BUILD_BUG_ON(rule.num_layers < LANDLOCK_MAX_NUM_LAYERS);
}
-static struct landlock_rule *
-create_rule(struct landlock_object *const object,
- const struct landlock_layer (*const layers)[], const u32 num_layers,
- const struct landlock_layer *const new_layer)
+static struct landlock_rule *create_rule(
+ struct landlock_object *const object_ptr,
+ const uintptr_t object_data,
+ const struct landlock_layer (*const layers)[],
+ const u32 num_layers,
+ const struct landlock_layer *const new_layer)
{
struct landlock_rule *new_rule;
u32 new_num_layers;
@@ -91,8 +93,15 @@ create_rule(struct landlock_object *const object,
if (!new_rule)
return ERR_PTR(-ENOMEM);
RB_CLEAR_NODE(&new_rule->node);
- landlock_get_object(object);
- new_rule->object = object;
+
+ if (object_ptr) {
+ landlock_get_object(object_ptr);
+ new_rule->object.ptr = object_ptr;
+ } else if (object_ptr && object_data) {
+ WARN_ON_ONCE(1);
+ return ERR_PTR(-EINVAL);
+ }
+
new_rule->num_layers = new_num_layers;
/* Copies the original layer stack. */
memcpy(new_rule->layers, layers,
@@ -108,7 +117,7 @@ static void free_rule(struct landlock_rule *const rule)
might_sleep();
if (!rule)
return;
- landlock_put_object(rule->object);
+ landlock_put_object(rule->object.ptr);
kfree(rule);
}
@@ -144,26 +153,44 @@ static void build_check_ruleset(void)
* access rights.
*/
static int insert_rule(struct landlock_ruleset *const ruleset,
- struct landlock_object *const object,
- const struct landlock_layer (*const layers)[],
- size_t num_layers)
+ struct landlock_object *const object_ptr,
+ uintptr_t object_data, u16 rule_type,
+ const struct landlock_layer (*const layers)[],
+ 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();
lockdep_assert_held(&ruleset->lock);
- if (WARN_ON_ONCE(!object || !layers))
+ /* Choose rb_tree structure depending on a rule type */
+
+ if (WARN_ON_ONCE(!layers))
return -ENOENT;
- walker_node = &(ruleset->root.rb_node);
+ if (WARN_ON_ONCE(object_ptr && object_data))
+ return -EINVAL;
+
+ switch (rule_type) {
+ case LANDLOCK_RULE_PATH_BENEATH:
+ if (WARN_ON_ONCE(!object_ptr))
+ return -ENOENT;
+ object_data = (uintptr_t)object_ptr;
+ root = &ruleset->root_inode;
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ return -EINVAL;
+ }
+ walker_node = &root->rb_node;
while (*walker_node) {
struct landlock_rule *const this =
rb_entry(*walker_node, struct landlock_rule, node);
- if (this->object != object) {
+ if (this->object.data != object_data) {
parent_node = *walker_node;
- if (this->object < object)
+ if (this->object.data < object_data)
walker_node = &((*walker_node)->rb_right);
else
walker_node = &((*walker_node)->rb_left);
@@ -195,11 +222,16 @@ static int insert_rule(struct landlock_ruleset *const ruleset,
* Intersects access rights when it is a merge between a
* ruleset and a domain.
*/
- new_rule = create_rule(object, &this->layers, this->num_layers,
- &(*layers)[0]);
+ switch (rule_type) {
+ case LANDLOCK_RULE_PATH_BENEATH:
+ new_rule = create_rule(object_ptr, 0, &this->layers,
+ this->num_layers,
+ &(*layers)[0]);
+ break;
+ }
if (IS_ERR(new_rule))
return PTR_ERR(new_rule);
- rb_replace_node(&this->node, &new_rule->node, &ruleset->root);
+ rb_replace_node(&this->node, &new_rule->node, &ruleset->root_inode);
free_rule(this);
return 0;
}
@@ -208,11 +240,15 @@ static int insert_rule(struct landlock_ruleset *const ruleset,
build_check_ruleset();
if (ruleset->num_rules >= LANDLOCK_MAX_NUM_RULES)
return -E2BIG;
- new_rule = create_rule(object, layers, num_layers, NULL);
+ switch (rule_type) {
+ case LANDLOCK_RULE_PATH_BENEATH:
+ new_rule = create_rule(object_ptr, 0, layers, num_layers, NULL);
+ break;
+ }
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, &ruleset->root);
+ rb_insert_color(&new_rule->node, &ruleset->root_inode);
ruleset->num_rules++;
return 0;
}
@@ -230,8 +266,10 @@ static void build_check_layer(void)
/* @ruleset must be locked by the caller. */
int landlock_insert_rule(struct landlock_ruleset *const ruleset,
- struct landlock_object *const object,
- const access_mask_t access)
+ struct landlock_object *const object_ptr,
+ const uintptr_t object_data,
+ const access_mask_t access,
+ const u16 rule_type)
{
struct landlock_layer layers[] = { {
.access = access,
@@ -240,7 +278,8 @@ int landlock_insert_rule(struct landlock_ruleset *const ruleset,
} };
build_check_layer();
- return insert_rule(ruleset, object, &layers, ARRAY_SIZE(layers));
+ return insert_rule(ruleset, object_ptr, object_data, rule_type, &layers,
+ ARRAY_SIZE(layers));
}
static inline void get_hierarchy(struct landlock_hierarchy *const hierarchy)
@@ -285,9 +324,9 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
dst->access_masks[dst->num_layers - 1] = src->access_masks[0];
/* Merges the @src tree. */
- rbtree_postorder_for_each_entry_safe(walker_rule, next_rule, &src->root,
- node) {
- struct landlock_layer layers[] = { {
+ rbtree_postorder_for_each_entry_safe(walker_rule, next_rule,
+ &src->root_inode, node) {
+ struct landlock_layer layers[] = {{
.level = dst->num_layers,
} };
@@ -300,7 +339,9 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
goto out_unlock;
}
layers[0].access = walker_rule->layers[0].access;
- err = insert_rule(dst, walker_rule->object, &layers,
+
+ err = insert_rule(dst, walker_rule->object.ptr, 0,
+ LANDLOCK_RULE_PATH_BENEATH, &layers,
ARRAY_SIZE(layers));
if (err)
goto out_unlock;
@@ -328,10 +369,10 @@ static int inherit_ruleset(struct landlock_ruleset *const parent,
/* Copies the @parent tree. */
rbtree_postorder_for_each_entry_safe(walker_rule, next_rule,
- &parent->root, node) {
- err = insert_rule(child, walker_rule->object,
- &walker_rule->layers,
- walker_rule->num_layers);
+ &parent->root_inode, node) {
+ err = insert_rule(child, walker_rule->object.ptr, 0,
+ LANDLOCK_RULE_PATH_BENEATH, &walker_rule->layers,
+ walker_rule->num_layers);
if (err)
goto out_unlock;
}
@@ -362,7 +403,8 @@ static void free_ruleset(struct landlock_ruleset *const ruleset)
struct landlock_rule *freeme, *next;
might_sleep();
- rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root, node)
+ rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_inode,
+ node)
free_rule(freeme);
put_hierarchy(ruleset->hierarchy);
kfree(ruleset);
@@ -452,22 +494,31 @@ landlock_merge_ruleset(struct landlock_ruleset *const parent,
/*
* The returned access has the same lifetime as @ruleset.
*/
-const struct landlock_rule *
-landlock_find_rule(const struct landlock_ruleset *const ruleset,
- const struct landlock_object *const object)
+const struct landlock_rule *landlock_find_rule(
+ const struct landlock_ruleset *const ruleset,
+ const uintptr_t object_data, const u16 rule_type)
{
const struct rb_node *node;
- if (!object)
+ if (!object_data)
return NULL;
- node = ruleset->root.rb_node;
+
+ switch (rule_type) {
+ case LANDLOCK_RULE_PATH_BENEATH:
+ node = ruleset->root_inode.rb_node;
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ return NULL;
+ }
+
while (node) {
struct landlock_rule *this =
rb_entry(node, struct landlock_rule, node);
- if (this->object == object)
+ if (this->object.data == object_data)
return this;
- if (this->object < object)
+ if (this->object.data < object_data)
node = node->rb_right;
else
node = node->rb_left;
diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
index f27a79624962..3066e5d7180c 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -54,15 +54,17 @@ struct landlock_rule {
*/
struct rb_node node;
/**
- * @object: Pointer to identify a kernel object (e.g. an inode). This
- * is used as a key for this ruleset element. This pointer is set once
- * and never modified. It always points to an allocated object because
- * each rule increments the refcount of its object.
- */
- struct landlock_object *object;
- /**
- * @num_layers: Number of entries in @layers.
+ * @object: 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. This pointer/@...ect.ptr/ is set once and
+ * never modified. It always points to an allocated object because each
+ * rule increments the refcount of its object (for inodes);
*/
+ union {
+ struct landlock_object *ptr;
+ uintptr_t data;
+ } object;
+
u32 num_layers;
/**
* @layers: Stack of layers, from the latest to the newest, implemented
@@ -99,7 +101,7 @@ struct landlock_ruleset {
* nodes. Once a ruleset is tied to a process (i.e. as a domain), this
* tree is immutable until @usage reaches zero.
*/
- struct rb_root root;
+ struct rb_root root_inode;
/**
* @hierarchy: Enables hierarchy identification even when a parent
* domain vanishes. This is needed for the ptrace protection.
@@ -161,16 +163,18 @@ void landlock_put_ruleset(struct landlock_ruleset *const ruleset);
void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset);
int landlock_insert_rule(struct landlock_ruleset *const ruleset,
- struct landlock_object *const object,
- const access_mask_t access);
+ struct landlock_object *const object_ptr,
+ const uintptr_t object_data,
+ const access_mask_t access,
+ const u16 rule_type);
struct landlock_ruleset *
landlock_merge_ruleset(struct landlock_ruleset *const parent,
struct landlock_ruleset *const ruleset);
-const struct landlock_rule *
-landlock_find_rule(const struct landlock_ruleset *const ruleset,
- const struct landlock_object *const object);
+const struct landlock_rule *landlock_find_rule(
+ const struct landlock_ruleset *const ruleset,
+ const uintptr_t object_data, const u16 rule_type);
static inline void landlock_get_ruleset(struct landlock_ruleset *const ruleset)
{
--
2.25.1
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