[v5,02/15] landlock: landlock_find/insert_rule refactoring

Message ID	20220516152038.39594-3-konstantin.meskhidze@huawei.com (mailing list archive)
State	Handled Elsewhere
Headers	show Return-Path: <linux-security-module-owner@kernel.org> From: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> To: <mic@digikod.net> CC: <willemdebruijn.kernel@gmail.com>, <linux-security-module@vger.kernel.org>, <netdev@vger.kernel.org>, <netfilter-devel@vger.kernel.org>, <yusongping@huawei.com>, <anton.sirazetdinov@huawei.com> Subject: [PATCH v5 02/15] landlock: landlock_find/insert_rule refactoring Date: Mon, 16 May 2022 23:20:25 +0800 Message-ID: <20220516152038.39594-3-konstantin.meskhidze@huawei.com> In-Reply-To: <20220516152038.39594-1-konstantin.meskhidze@huawei.com> References: <20220516152038.39594-1-konstantin.meskhidze@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII Precedence: bulk
Series	Network support for Landlock \| expand [v5,00/15] Network support for Landlock [v5,01/15] landlock: access mask renaming [v5,02/15] landlock: landlock_find/insert_rule refactoring [v5,03/15] landlock: merge and inherit function refactoring [v5,04/15] landlock: helper functions refactoring [v5,05/15] landlock: landlock_add_rule syscall refactoring [v5,06/15] landlock: user space API network support [v5,07/15] landlock: add support network rules [v5,08/15] landlock: TCP network hooks implementation [v5,09/15] seltests/landlock: add tests for bind() hooks [v5,10/15] seltests/landlock: add tests for connect() hooks [v5,11/15] seltests/landlock: connect() with AF_UNSPEC tests [v5,12/15] seltests/landlock: rules overlapping test [v5,13/15] seltests/landlock: ruleset expanding test [v5,14/15] seltests/landlock: invalid user input data test [v5,15/15] samples/landlock: adds network demo

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/@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 @@ -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) {

[v5,02/15] landlock: landlock_find/insert_rule refactoring

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