Trusted IO Routing via Shadow CAM Validation
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Solution Overview
Problem
In computing systems, IO data is transmitted in the clear between the Crypto Engine and the IO device controller, exposing secrets when routed through a host-controlled fabric, which may be untrusted, compromising security.
Innovation Solution
Implementing a trusted IO configuration with Content Addressable Memory (CAM) and shadow CAMs to securely route IO transactions, using Channel IDs (CIDs) for authentication and encryption, ensuring only trusted data reaches its intended destination and preventing redirection to untrusted agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If data is transmitted in the clear between Crypto Engine and IO device controller through host-controlled fabric, then routing flexibility and ease of operation are improved, but security and data confidentiality deteriorate due to potential exposure to untrusted software
Solution Approach 1:
The fabric is segmented into secure and unsecure regions using shadow CAMs. Secure transactions are routed through protected paths validated by shadow CAM entries, while unsecure transactions follow standard fabric routing. This segmentation allows routing flexibility for unsecure traffic while protecting secure traffic from interception by untrusted software.
Solution Approach 2:
Shadow CAMs act as intermediary validation layers between the Crypto Engine and IO device controllers. Before routing secure transactions, the fabric verifies shadow CAM entries that authenticate the transaction's legitimacy. This intermediary mechanism prevents untrusted software from redirecting secure data while maintaining normal fabric operation for non-secure traffic.
2Object-affected harmful factors
If shadow CAMs and routing validation mechanisms are implemented to prevent data redirection, then security and data confidentiality are improved, but device complexity and manufacturing complexity increase
Solution Approach 1:
The shadow CAM structure reuses existing fabric routing infrastructure and CAM technologies already present in modern switches and routers. The same fabric switching fabric handles both secure and unsecure traffic, while shadow CAMs provide an additional validation layer. This multi-functionality approach minimizes added complexity by leveraging existing components rather than introducing entirely new architecture.
Solution Approach 2:
Shadow CAM entries are pre-configured with valid destination information before secure transactions occur. The fabric validates transactions against these pre-established entries, eliminating the need for complex real-time security decisions during transaction routing. This preliminary configuration simplifies the runtime operation and reduces the computational burden on the fabric.
3Object-affected harmful factors
If all IO transactions are encrypted and routed through secure paths, then data confidentiality is improved, but processing time and productivity decrease due to additional validation overhead
Solution Approach 1:
Instead of securing all IO transactions, the system applies security measures only to transactions that require confidentiality (those involving Crypto Engine and sensitive IO controllers). The shadow CAM validation is selectively enabled based on transaction type and destination, allowing unencrypted, high-speed routing for non-sensitive traffic while providing enhanced protection where needed.
Solution Approach 2:
Security validation through shadow CAMs is applied locally only to specific fabric ports and transaction types that require protection. The fabric can operate in secure mode for specific IO controllers while maintaining standard high-speed routing for other controllers. This localized approach ensures data confidentiality for sensitive operations without imposing validation overhead on all transactions.
Data Source
AI summary
Various configurations and methods for securing and validating trusted input output (IO) data communications within fabric interconnects of processing circuitry are disclosed herein. As an example, a technique for secure routing of trusted software transactions includes operations of a crypto engine and an IO hub to validate trusted transactions such as DMA read and write transactions received from a trusted IO controller, and configuring the fabrics of the circuitry to prevent re-routing or tampering of data from the trusted transactions. In an example, hardware-based identification and verification of the trusted transactions may be performed with use of content addressable memory at the crypto engine and the respective unsecure fabrics, to identify and enforce the trusted transactions that cannot be re-routed. As a result, rogue agents or entities connected to the unsecure fabrics cannot interfere with or intercept data for trusted transactions.