Kernel Space Firewall Filter Hooks for Dynamic Packet Offsets

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Solution Overview

Problem

Traditional firewall filters in kernel space often fail to correctly apply rules to packets with dynamically offset headers, allowing unwanted and malicious traffic to bypass security measures, leading to potential network intrusions and inefficiencies.

Innovation Solution

A method and system that involve a tunnel driver in kernel space to identify and correct the application of firewall rules by adjusting packet headers at dynamic offsets, ensuring proper filtering before allowing packets to exit kernel space, using metadata and firewall filter hooks to apply rules at the correct positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional firewall filters are applied in kernel space, then network security is improved by blocking unwanted traffic, but packets with dynamically offset headers can evade filtering and bypass security measures

Engineering Contradiction:

Improvenetwork securityVSAvoidability to handle packets with dynamic offsets

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The firewall filter hook is made dynamic by allowing it to be invoked at configurable positions within the packet processing pipeline. The system determines the appropriate hook position based on packet characteristics, enabling the firewall to adaptively handle packets with varying header structures and offsets while maintaining security enforcement.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the parameter of firewall filter invocation position from a fixed location to a dynamic location determined by packet metadata. By adjusting where the firewall hook is inserted in the processing pipeline based on packet type and header offset information, the system maintains effective filtering for both standard and non-standard packet formats.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If firewall filters are applied early in the packet processing pipeline, then processing efficiency is improved, but packets with offset headers may miss the filter or have rules applied incorrectly

Engineering Contradiction:

Improvepacket processing efficiencyVSAvoidaccuracy of firewall rule application

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system performs preliminary identification of packet characteristics and determination of the appropriate firewall hook position before invoking the filter. By pre-processing packet metadata to identify header offsets and determining the correct insertion point for the firewall hook, the system ensures that filtering occurs at the optimal position for each packet type, maintaining both efficiency and accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention introduces an intermediary mechanism that sits between the packet processing pipeline and the firewall filter hook. This intermediary layer analyzes packet metadata, determines the appropriate filter invocation position, and dynamically inserts or positions the firewall hook accordingly, ensuring accurate rule application without sacrificing processing throughput.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If a fixed position firewall hook is used, then the system complexity is reduced, but it cannot correctly handle packets with dynamically offset headers

Engineering Contradiction:

Improvefirewall filter implementation complexityVSAvoidcapability to handle various packet formats

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The firewall filter hook mechanism is designed to serve multiple functions: it can operate at fixed positions for standard packets and dynamically positioned locations for packets with offset headers. By making the hook system universal and capable of adapting to different packet formats through metadata analysis, the invention maintains relatively simple implementation while achieving high versatility in handling various packet types.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11388140B1Apparatus, system, and method for applying firewall rules at dynamic offsets within packets in kernel space

Publication Date: 2022.07.12 JUNIPER NETWORKS INC

AI summary

A disclosed method may include (1) receiving a packet at a tunnel driver in kernel space on a routing engine of a network device, (2) identifying, at the tunnel driver, metadata of the packet that indicates whether at least one firewall filter had already been correctly applied to the packet before the packet arrived at the tunnel driver, (3) determining, based at least in part on the metadata of the packet, that the firewall filter had not been correctly applied to the packet before the packet arrived at the tunnel driver, and then in response to determining that the firewall filter had not been correctly applied to the packet, (4) invoking at least one firewall filter hook that applies at least one firewall rule on the packet before the packet is allowed to exit kernel space on the routing engine. Various other apparatuses, systems, and methods are also disclosed.