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process_vm_readv

Intro

process_vm_readv - a system call that reads data from the memory of another process

Description

The process_vm_readv system call is used to read data from the address space of another process. It is analogous to readv, with the only difference being that the source of the data is in the memory of another process. This system call is useful for reading data from other processes, without the need for an inter-process communication mechanism or sharing memory between the two processes.

There are some drawbacks and advantages to using this system call. The main drawback is that it does not guarantee atomicity of the transaction, meaning that the data read from another process may become inconsistent, due to changes made in the other process between the time the data was read and the time the request was made. On the other hand, it allows multiple processes to access and share data without having to go through expensive sharing mechanisms such as semaphores or shared memory.

Arguments

  • pid:pid_t[K] - The process ID of the remote process from which data will be read.
  • local_iov:const struct iovec*[U] - A pointer to a struct iovec object that describes the local memory where the read data will be stored.
  • liovcnt:unsigned long[K] - The number of elements in local_iov.
  • remote_iov:const struct iovec*[U] - A pointer to a struct iovec object with similar contents to local_iov, but for the remote process.
  • riovcnt:unsigned long[K] - The number of elements in remote_iov.
  • flags:unsigned long[K] - A set of flags that defines the behavior of the transaction (e.g. 0: no flags, PROCESS_VM_READ: reading from remote address space).

Available Tags

  • K - Originated from kernel-space.
  • U - Originated from user space (for example, pointer to user space memory used to get it)
  • TOCTOU - Vulnerable to TOCTOU (time of check, time of use).
  • OPT - Optional argument - might not always be available (passed with null value).

Hooks

do_process_vm_readv

Type

kprobe

Purpose

Hooking this function will allow to detect when a process invokes the process_vm_readv system call.

Example Use Case

This system call can be used for implementing a safe inter-process communication method. The two processes can use process_vm_readv to exchange data without having to resort to expensive synchronization mechanisms such as semaphores or shared memory.

Issues

This system call does not guarantee atomicity, which can lead to reading inconsistent data.

  • process_vm_writev - Writes data to the address space of another process.
  • readv - Reads data from a file into the user space.
  • writev - Writes data to a file.

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.