3/16/2022 11:27 AM, Mickaël Salaün пишет:
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.
Ok. I got it.
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).
But rule_type is needed here in coming commits to support networkrules. For LANDLOCK_RULE_PATH_BENEATH rule type landlock_get_object() is used but for LANDLOCK_RULE_NET_SERVICE is not. Using rule type is convenient for distinguising between fs and network rules.
+ } + 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.
But anyway in coming commits with network rules this code will be moved into case LANDLOCK_RULE_PATH_BENEATH: ....
- 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).What about coming commits with network rule_type support?+ 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.
What about your suggestion to use 2 rb_tress to support different rule_types:
1. root_inode - for filesystem objects
2. root_net_port - for network port objects
????
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.
Got it. Thanks.
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.
I got it. I will refactor it.
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().
Sorry, I did not get your point.Do you mean I should check the correctness of rule_type in above function which calls landlock_find_rule() ??? Why can't I add such check here?
+ } + 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).
Ok. I will mofdify this line
This is used as a key for this ruleset element.+ * This pointer is set once and never modified. It always points to ans/This pointer/@object.ptr/
Ok. I got it.
+ * 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.
