function::set_kernel_string_n - Linux

Overview

The function::set_kernel_string_n command dynamically adjusts the kernel string table at runtime, allowing the modification of existing string entries or the addition of new strings. It’s particularly useful for modules that need to insert custom strings dynamically, such as error messages, configuration information, or other runtime-generated text.

Syntax

function::set_kernel_string_n <string_index> <new_string>

Options/Flags

| Option | Description |
|—|—|
| string_index | The index of the kernel string to be modified or added. |
| new_string | The new string value to be set at the specified index. |

Examples

Example 1: Setting a New Error Message

To set a custom error message at kernel string index 10:

function::set_kernel_string_n 10 "Custom Error Message"

Example 2: Adding a Configuration String

To add a new string to the kernel string table at index 25:

function::set_kernel_string_n 25 "Module Configuration: custom"

Common Issues

  • Index Out of Range: Ensure that the specified string index is within the valid range of the kernel string table.
  • String Overflow: The provided string should not exceed the maximum length allowed for kernel strings.
  • Permission Denied: The command requires root privileges to modify the kernel string table.

Integration

The function::set_kernel_string_n command can be integrated with other tools for advanced tasks:

  • kprobe: Monitor the kernel string table modification in real-time using kprobes.
  • lsmod: Check the contents of the kernel string table by examining the output of lsmod.

Related Commands

  • kset_show: Displays the contents of kernel string tables.
  • ksyms: Search through the kernel symbol table, including kernel strings.