Feature Request: Add Read-Only CTX Descriptor.

[gtrevi]

Description:

I would like to propose the addition of a feature that allows the declaration of the CTX descriptor as read-only. This enhancement would enable scenarios where buffers are passed in fast pipelines, such as networking data paths, without the need for memory allocation.

Rationale:

Currently, the verifier permits BPF programs to modify the context buffer, which necessitates memory allocation to prevent potential issues. This can lead to catastrophic failures, as the modified memory may be reused by the caller for further processing. By allowing the CTX descriptor to be read-only, we can ensure the integrity of the context buffer and improve the efficiency of data processing pipelines.

Benefits:

• Avoids unnecessary memory allocation.
• Prevents potential catastrophic failures due to unintended modifications.
• Improves performance in fast data pipelines, especially in networking scenarios.