Re: [RFC PATCH v4 08/15] landlock: add support network rules

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On 09/03/2022 14:44, Konstantin Meskhidze wrote:
This modification adds network rules support
in internal landlock functions (presented in ruleset.c)
and landlock_create_ruleset syscall.

Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@xxxxxxxxxx>
---

Changes since v3:
* Split commit.
* Add network rule support for internal landlock functions.
* Add set_masks and get_masks for network.
* Add rb_root root_net_port.

---
  security/landlock/fs.c       |  2 +-
  security/landlock/limits.h   |  6 +++
  security/landlock/ruleset.c  | 88 +++++++++++++++++++++++++++++++++---
  security/landlock/ruleset.h  | 14 +++++-
  security/landlock/syscalls.c | 10 +++-
  5 files changed, 109 insertions(+), 11 deletions(-)

diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 75ebdce5cd16..5cd339061cdb 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -231,7 +231,7 @@ static int check_access_path(const struct landlock_ruleset *const domain,

  			inode = d_backing_inode(walker_path.dentry);
  			object_ptr = landlock_inode(inode)->object;
-			layer_mask = landlock_unmask_layers(domain, object_ptr,
+			layer_mask = landlock_unmask_layers(domain, object_ptr, 0,
  							access_request, layer_mask,
  							LANDLOCK_RULE_PATH_BENEATH);
  			if (layer_mask == 0) {
diff --git a/security/landlock/limits.h b/security/landlock/limits.h
index 2a0a1095ee27..fdbef85e4de0 100644
--- a/security/landlock/limits.h
+++ b/security/landlock/limits.h
@@ -18,4 +18,10 @@
  #define LANDLOCK_LAST_ACCESS_FS		LANDLOCK_ACCESS_FS_MAKE_SYM
  #define LANDLOCK_MASK_ACCESS_FS		((LANDLOCK_LAST_ACCESS_FS << 1) - 1)

+#define LANDLOCK_LAST_ACCESS_NET	LANDLOCK_ACCESS_NET_CONNECT_TCP
+#define LANDLOCK_MASK_ACCESS_NET	((LANDLOCK_LAST_ACCESS_NET << 1) - 1)
+#define LANDLOCK_MASK_SHIFT_NET		16
+
+#define LANDLOCK_RULE_TYPE_NUM		LANDLOCK_RULE_NET_SERVICE
+
  #endif /* _SECURITY_LANDLOCK_LIMITS_H */
diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index 7179b10f3538..1cecca59a942 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -35,6 +35,7 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
  	refcount_set(&new_ruleset->usage, 1);
  	mutex_init(&new_ruleset->lock);
  	new_ruleset->root_inode = RB_ROOT;
+	new_ruleset->root_net_port = RB_ROOT;
  	new_ruleset->num_layers = num_layers;
  	/*
  	 * hierarchy = NULL
@@ -58,16 +59,32 @@ u32 landlock_get_fs_access_mask(const struct landlock_ruleset *ruleset, u16 mask
  	return ruleset->access_masks[mask_level];
  }

+/* A helper function to set a network mask */
+void landlock_set_net_access_mask(struct landlock_ruleset *ruleset,
+				  const struct landlock_access_mask *access_mask_set,
+				  u16 mask_level)
+{
+	ruleset->access_masks[mask_level] |= (access_mask_set->net << LANDLOCK_MASK_SHIFT_NET);
+}
+
+/* A helper function to get a network mask */
+u32 landlock_get_net_access_mask(const struct landlock_ruleset *ruleset, u16 mask_level)
+{
+	return (ruleset->access_masks[mask_level] >> LANDLOCK_MASK_SHIFT_NET);
+}

Both these helpers should be "static inline" and moved in net.h


+
  struct landlock_ruleset *landlock_create_ruleset(const struct landlock_access_mask *access_mask_set)
  {
  	struct landlock_ruleset *new_ruleset;

  	/* Informs about useless ruleset. */
-	if (!access_mask_set->fs)
+	if (!access_mask_set->fs && !access_mask_set->net)
  		return ERR_PTR(-ENOMSG);
  	new_ruleset = create_ruleset(1);
-	if (!IS_ERR(new_ruleset))

This is better:

if (IS_ERR(new_ruleset))
	return new_ruleset;
if (access_mask_set->fs)
...


+	if (!IS_ERR(new_ruleset) && access_mask_set->fs)
  		landlock_set_fs_access_mask(new_ruleset, access_mask_set, 0);
+	if (!IS_ERR(new_ruleset) && access_mask_set->net)
+		landlock_set_net_access_mask(new_ruleset, access_mask_set, 0);
  	return new_ruleset;
  }

@@ -111,6 +128,9 @@ static struct landlock_rule *create_rule(
  		landlock_get_object(object_ptr);
  		new_rule->object.ptr = object_ptr;
  		break;
+	case LANDLOCK_RULE_NET_SERVICE:
+		new_rule->object.data = object_data;
+		break;
  	default:
  		return ERR_PTR(-EINVAL);
  	}
@@ -145,10 +165,12 @@ static void build_check_ruleset(void)
  		.num_layers = ~0,
  	};
  	typeof(ruleset.access_masks[0]) fs_access_mask = ~0;
+	typeof(ruleset.access_masks[0]) net_access_mask = ~0;

  	BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES);
  	BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS);
  	BUILD_BUG_ON(fs_access_mask < LANDLOCK_MASK_ACCESS_FS);
+	BUILD_BUG_ON(net_access_mask < LANDLOCK_MASK_ACCESS_NET);
  }

  /**
@@ -191,6 +213,12 @@ static int insert_rule(struct landlock_ruleset *const ruleset,

Already reviewed.

[...]


@@ -319,6 +363,9 @@ static int tree_merge(struct landlock_ruleset *const src,
  	case LANDLOCK_RULE_PATH_BENEATH:
  		src_root = &src->root_inode;
  		break;
+	case LANDLOCK_RULE_NET_SERVICE:
+		src_root = &src->root_net_port;
+		break;
  	default:
  		return -EINVAL;
  	}
@@ -338,11 +385,14 @@ static int tree_merge(struct landlock_ruleset *const src,
  			return err;
  		}
  		layers[0].access = walker_rule->layers[0].access;
-

nit: Please keep this empty line.


  		switch (rule_type) {
  		case LANDLOCK_RULE_PATH_BENEATH:
  			err = insert_rule(dst, walker_rule->object.ptr, 0, &layers,
-				ARRAY_SIZE(layers), rule_type);
+					ARRAY_SIZE(layers), rule_type);

Please don't insert this kind of formatting in unrelated patches.


+			break;
+		case LANDLOCK_RULE_NET_SERVICE:
+			err = insert_rule(dst, NULL, walker_rule->object.data, &layers,
+					ARRAY_SIZE(layers), rule_type);
  			break;
  		}
  		if (err)
@@ -379,6 +429,10 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
  	err = tree_merge(src, dst, LANDLOCK_RULE_PATH_BENEATH);
  	if (err)
  		goto out_unlock;
+	/* Merges the @src network tree. */
+	err = tree_merge(src, dst, LANDLOCK_RULE_NET_SERVICE);
+	if (err)
+		goto out_unlock;

  out_unlock:
  	mutex_unlock(&src->lock);
@@ -398,6 +452,9 @@ static int tree_copy(struct landlock_ruleset *const parent,
  	case LANDLOCK_RULE_PATH_BENEATH:
  		parent_root = &parent->root_inode;
  		break;
+	case LANDLOCK_RULE_NET_SERVICE:
+		parent_root = &parent->root_net_port;
+		break;
  	default:
  		return -EINVAL;
  	}
@@ -410,6 +467,11 @@ static int tree_copy(struct landlock_ruleset *const parent,
  				  &walker_rule->layers, walker_rule->num_layers,
  				  rule_type);
  			break;
+		case LANDLOCK_RULE_NET_SERVICE:
+			err = insert_rule(child, NULL, walker_rule->object.data,
+				  &walker_rule->layers, walker_rule->num_layers,
+				  rule_type);
+			break;
  		}
  		if (err)
  			return err;
@@ -432,6 +494,10 @@ static int inherit_ruleset(struct landlock_ruleset *const parent,

  	/* Copies the @parent inode tree. */
  	err = tree_copy(parent, child, LANDLOCK_RULE_PATH_BENEATH);
+	if (err)
+		goto out_unlock;
+	/* Copies the @parent inode tree. */
+	err = tree_copy(parent, child, LANDLOCK_RULE_NET_SERVICE);
  	if (err)
  		goto out_unlock;

@@ -464,6 +530,9 @@ static void free_ruleset(struct landlock_ruleset *const ruleset)
  	rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_inode,
  			node)
  		free_rule(freeme, LANDLOCK_RULE_PATH_BENEATH);
+	rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_net_port,
+			node)
+		free_rule(freeme, LANDLOCK_RULE_NET_SERVICE);
  	put_hierarchy(ruleset->hierarchy);
  	kfree(ruleset);
  }
@@ -565,6 +634,9 @@ const struct landlock_rule *landlock_find_rule(
  	case LANDLOCK_RULE_PATH_BENEATH:
  		node = ruleset->root_inode.rb_node;
  		break;
+	case LANDLOCK_RULE_NET_SERVICE:
+		node = ruleset->root_net_port.rb_node;
+		break;
  	default:
  		return ERR_PTR(-EINVAL);
  	}
@@ -586,8 +658,8 @@ const struct landlock_rule *landlock_find_rule(
  /* Access-control management */
  u64 landlock_unmask_layers(const struct landlock_ruleset *const domain,
  			   const struct landlock_object *object_ptr,
-			   const u32 access_request, u64 layer_mask,
-			   const u16 rule_type)
+			   const u16 port, const u32 access_request,
+			   u64 layer_mask, const u16 rule_type)
  {
  	const struct landlock_rule *rule;
  	size_t i;
@@ -600,6 +672,10 @@ u64 landlock_unmask_layers(const struct landlock_ruleset *const domain,
  			LANDLOCK_RULE_PATH_BENEATH);
  		rcu_read_unlock();
  		break;
+	case LANDLOCK_RULE_NET_SERVICE:
+		rule = landlock_find_rule(domain, (uintptr_t)port,

Type casting should not be required.

[...]



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