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io_submit

Intro

io_submit - submit I/O request(s) to an io_context

Description

io_submit requests the kernel to perform I/O specified in the given iocb array, which is a list of I/O request blocks. All the I/O operations occur in the given context. This can be used to submit multiple I/O operations within a single system call, reducing the overhead of invoking a system call for each I/O operation.

The I/O request list may contain I/O operations on different types of files such as regular files, pipes, block devices, etc. However, it is circular in nature and any links pointing outside the given context must not be followed, since the context stores only the local file descriptors.

Although this syscall is usually considered less error-prone than other syscalls that require manual memory management in the user space, it can be vulnerable to Time Of Check-Time Of Use (TOCTOU) attacks on the io_context_t structure. If a race condition exists between the io_context_t structure copying in the user space and the corresponding io_context_t structure's modification in the kernel space, an attacker can exploit this vulnerability to get the system call to fail.

Arguments

  • ctx_id:io_context_t[K] - This is an opaque context structure which is used to send multiple I/O operations within a single system call.
  • nr:long[K] - This is the number of elements in the iocbpp array.
  • iocbpp:struct iocb**[K] - This is the array of iocb structures which define the I/O operations to be performed.

Available Tags

  • K - Originated from kernel-space.

Hooks

cond_resched

Type

NONE

Purpose

To prevent unbounded execution in kernel space.

Example Use Case

One example use case of io_submit is to submit multiple read requests to the kernel in one system call. This reduces the overhead of invoking a system call for each read operation, thereby improving the performance of the program.

Issues

No known issues.

  • io_prep_pwrite
  • io_cancel
  • io_getevents

This document was automatically generated by OpenAI and needs review. It might not be accurate and might contain errors. The authors of Tracee recommend that the user reads the "events.go" source file to understand the events and their arguments better.