[PATCH v6 02/17] landlock: refactors landlock_find/insert_rule
Konstantin Meskhidze
konstantin.meskhidze at huawei.com
Tue Jun 21 08:22:58 UTC 2022
Adds a new object union to support a socket port
rule type. Refactors landlock_insert_rule() and
landlock_find_rule() to support coming network
modifications. 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 at huawei.com>
---
Changes since v5:
* Formats code with clang-format-14.
Changes since v4:
* Refactors insert_rule() and create_rule() functions by deleting
rule_type from their arguments list, it helps to reduce useless code.
Changes since v3:
* Splits commit.
* Refactors landlock_insert_rule and landlock_find_rule functions.
* Rename new_ruleset->root_inode.
---
security/landlock/fs.c | 7 ++-
security/landlock/ruleset.c | 105 ++++++++++++++++++++++++++----------
security/landlock/ruleset.h | 27 +++++-----
3 files changed, 96 insertions(+), 43 deletions(-)
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index e6da08ed99d1..46aedc2a05a8 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()
@@ -204,7 +205,9 @@ 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));
+ 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 a3fd58d01f09..5f13f8a12aee 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
@@ -69,7 +69,8 @@ static void build_check_rule(void)
}
static struct landlock_rule *
-create_rule(struct landlock_object *const object,
+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)
{
@@ -90,8 +91,15 @@ 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,
@@ -107,7 +115,7 @@ 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);
}
@@ -143,26 +151,42 @@ static void build_check_ruleset(void)
* access rights.
*/
static int insert_rule(struct landlock_ruleset *const ruleset,
- struct landlock_object *const object,
+ 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))
+ if (WARN_ON_ONCE(!layers))
return -ENOENT;
- walker_node = &(ruleset->root.rb_node);
+ if (WARN_ON_ONCE(object_ptr && object_data))
+ return -EINVAL;
+ /* Chooses rb_tree structure depending on a rule type. */
+ 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);
@@ -194,11 +218,16 @@ 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;
}
@@ -207,11 +236,15 @@ 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;
}
@@ -229,8 +262,9 @@ 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,
@@ -239,7 +273,8 @@ 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)
@@ -284,8 +319,8 @@ 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) {
+ rbtree_postorder_for_each_entry_safe(walker_rule, next_rule,
+ &src->root_inode, node) {
struct landlock_layer layers[] = { {
.level = dst->num_layers,
} };
@@ -299,7 +334,8 @@ 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;
@@ -327,8 +363,9 @@ 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,
+ &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)
@@ -361,7 +398,8 @@ 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);
@@ -453,20 +491,29 @@ landlock_merge_ruleset(struct landlock_ruleset *const parent,
*/
const struct landlock_rule *
landlock_find_rule(const struct landlock_ruleset *const ruleset,
- const struct landlock_object *const object)
+ 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 bd7ab39859bf..a22d132c32a7 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -53,15 +53,17 @@ 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/@object.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
@@ -98,7 +100,7 @@ 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.
@@ -160,8 +162,9 @@ 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,
@@ -169,7 +172,7 @@ landlock_merge_ruleset(struct landlock_ruleset *const parent,
const struct landlock_rule *
landlock_find_rule(const struct landlock_ruleset *const ruleset,
- const struct landlock_object *const object);
+ 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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