On 09/03/2022 14:44, Konstantin Meskhidze wrote:
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@xxxxxxxxxx>
---
Changes since v3:
* Split commit.
* Refactoring landlock_insert_rule and landlock_find_rule functions.
* Rename new_ruleset->root_inode.
---
security/landlock/fs.c | 5 +-
security/landlock/ruleset.c | 108 +++++++++++++++++++++++++-----------
security/landlock/ruleset.h | 26 +++++----
3 files changed, 94 insertions(+), 45 deletions(-)
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 97f5c455f5a7..1497948d754f 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -168,7 +168,7 @@ 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);
For consistency, please use 80 columns everywhere.
mutex_unlock(&ruleset->lock);
/*
* No need to check for an error because landlock_insert_rule()
@@ -195,7 +195,8 @@ static inline u64 unmask_layers(
inode = d_backing_inode(path->dentry);
rcu_read_lock();
rule = landlock_find_rule(domain,
- rcu_dereference(landlock_inode(inode)->object));
+ (uintptr_t)rcu_dereference(landlock_inode(inode)->object),
+ LANDLOCK_RULE_PATH_BENEATH);
rcu_read_unlock();
if (!rule)
return layer_mask;
diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index a6212b752549..971685c48641 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -34,7 +34,7 @@ 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
@@ -81,10 +81,12 @@ static void build_check_rule(void)
}
static struct landlock_rule *create_rule(
- struct landlock_object *const object,
+ 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)
+ const struct landlock_layer *const new_layer,
+ const u16 rule_type)
{
struct landlock_rule *new_rule;
u32 new_num_layers;
@@ -103,8 +105,16 @@ static struct landlock_rule *create_rule(
if (!new_rule)
return ERR_PTR(-ENOMEM);
RB_CLEAR_NODE(&new_rule->node);
- landlock_get_object(object);
- new_rule->object = object;
+
+ switch (rule_type) {
+ case LANDLOCK_RULE_PATH_BENEATH:
+ landlock_get_object(object_ptr);
+ new_rule->object.ptr = object_ptr;
+ break;
+ default:
+ return ERR_PTR(-EINVAL);
This would lead to memory leak. You should at least add a
WARN_ON_ONCE(1) here, but a proper solution would be to remove the use
of rule_type and only rely on object_ptr and object_data values. You can
also add a WARN_ON_ONCE(object_ptr && object_data).
+ }
+
new_rule->num_layers = new_num_layers;
/* Copies the original layer stack. */
memcpy(new_rule->layers, layers,
@@ -120,7 +130,7 @@ 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);
}
@@ -156,26 +166,38 @@ 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,
+ const uintptr_t object_data,
const struct landlock_layer (*const layers)[],
- size_t num_layers)
+ size_t num_layers, u16 rule_type)
{
struct rb_node **walker_node;
struct rb_node *parent_node = NULL;
struct landlock_rule *new_rule;
+ uintptr_t object;
+ struct rb_root *root;
might_sleep();
lockdep_assert_held(&ruleset->lock);
- if (WARN_ON_ONCE(!object || !layers))
- return -ENOENT;
You can leave this code here.
- walker_node = &(ruleset->root.rb_node);
+ /* Choose rb_tree structure depending on a rule type */
+ switch (rule_type) {
+ case LANDLOCK_RULE_PATH_BENEATH:
+ if (WARN_ON_ONCE(!object_ptr || !layers))
+ return -ENOENT;
+ object = (uintptr_t)object_ptr;
+ root = &ruleset->root_inode;
+ break;
+ default:
+ 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) {
parent_node = *walker_node;
- if (this->object < object)
+ if (this->object.data < object)
walker_node = &((*walker_node)->rb_right);
else
walker_node = &((*walker_node)->rb_left);
@@ -207,11 +229,15 @@ 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:
Same here and for the following code, you should replace such
switch/case with an if (object_ptr).
+ new_rule = create_rule(object_ptr, 0, &this->layers, this->num_layers,
+ &(*layers)[0], rule_type);
+ 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);
Use the root variable here. Same for the following code and patches.
free_rule(this);
return 0;
}
@@ -220,11 +246,15 @@ 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, rule_type);
+ 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;
}
@@ -242,7 +272,9 @@ 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 u32 access)
+ struct landlock_object *const object_ptr,
+ const uintptr_t object_data,
+ const u32 access, const u16 rule_type)
{
struct landlock_layer layers[] = {{
.access = access,
@@ -251,7 +283,8 @@ 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, &layers,
+ ARRAY_SIZE(layers), rule_type);
}
static inline void get_hierarchy(struct landlock_hierarchy *const hierarchy)
@@ -297,7 +330,7 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
/* Merges the @src tree. */
rbtree_postorder_for_each_entry_safe(walker_rule, next_rule,
- &src->root, node) {
+ &src->root_inode, node) {
struct landlock_layer layers[] = {{
.level = dst->num_layers,
}};
@@ -311,8 +344,8 @@ 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,
- ARRAY_SIZE(layers));
+ err = insert_rule(dst, walker_rule->object.ptr, 0, &layers,
+ ARRAY_SIZE(layers), LANDLOCK_RULE_PATH_BENEATH);
if (err)
goto out_unlock;
}
@@ -323,6 +356,8 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
return err;
}
+
+
Useless lines.
static int inherit_ruleset(struct landlock_ruleset *const parent,
struct landlock_ruleset *const child)
{
@@ -339,9 +374,10 @@ 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,
+ &walker_rule->layers, walker_rule->num_layers,
+ LANDLOCK_RULE_PATH_BENEATH);
if (err)
goto out_unlock;
}
@@ -372,7 +408,7 @@ 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,
+ rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_inode,
node)
free_rule(freeme);
put_hierarchy(ruleset->hierarchy);
@@ -465,20 +501,28 @@ struct landlock_ruleset *landlock_merge_ruleset(
*/
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)
object_data can be 0. You need to add a test with such value.
We need to be sure that this change cannot affect the current FS code.
return NULL;
- node = ruleset->root.rb_node;
+
+ switch (rule_type) {
+ case LANDLOCK_RULE_PATH_BENEATH:
+ node = ruleset->root_inode.rb_node;
+ break;
+ default:
+ return ERR_PTR(-EINVAL);
This is a bug. There is no check for such value. You need to check and
update all call sites to catch such errors. Same for all new use of
ERR_PTR().
+ }
+
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 bc87e5f787f7..088b8d95f653 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -50,15 +50,17 @@ 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 socket port object.
…or a raw data value (e.g. a network socket port).
This is used as a key for this ruleset element.
+ * This pointer is set once and never modified. It always points to an
s/This pointer/@object.ptr/
+ * 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
@@ -95,7 +97,7 @@ 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.
@@ -157,7 +159,9 @@ 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 u32 access);
+ struct landlock_object *const object_ptr,
+ const uintptr_t object_data,
+ const u32 access, const u16 rule_type);
struct landlock_ruleset *landlock_merge_ruleset(
struct landlock_ruleset *const parent,
@@ -165,7 +169,7 @@ struct landlock_ruleset *landlock_merge_ruleset(
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
