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gvisor/pkg/usermem
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Zach Koopmans ce58d71fd5 [syserror] Remove pkg syserror. 
Removes package syserror and moves still relevant code to either linuxerr
or to syserr (to be later removed).

Internal errors are converted from random types to *errors.Error types used
in linuxerr. Internal errors are in linuxerr/internal.go.

PiperOrigin-RevId: 390724202
 		2021-08-13 17:16:52 -07:00
..
BUILD [syserror] Update syserror to linuxerr for more errors. 2021-07-12 15:26:20 -07:00
README.md
…
bytes_io.go [syserror] Update syserror to linuxerr for more errors. 2021-07-12 15:26:20 -07:00
bytes_io_unsafe.go [syserror] Split usermem package 2021-03-29 13:30:21 -07:00
marshal.go Remove usermem dependency from marshal 2021-06-13 19:23:55 -07:00
usermem.go [syserror] Remove pkg syserror. 2021-08-13 17:16:52 -07:00
usermem_test.go [syserror] Update syserror to linuxerr for more errors. 2021-07-12 15:26:20 -07:00

README.md

This package defines primitives for sentry access to application memory.

Major types:

  • The IO interface represents a virtual address space and provides I/O methods on that address space. IO is the lowest-level primitive. The primary implementation of the IO interface is mm.MemoryManager.

  • IOSequence represents a collection of individually-contiguous address ranges in a IO that is operated on sequentially, analogous to Linux's struct iov_iter.

Major usage patterns:

  • Access to a task's virtual memory, subject to the application's memory protections and while running on that task's goroutine, from a context that is at or above the level of the kernel package (e.g. most syscall implementations in syscalls/linux); use the kernel.Task.Copy* wrappers defined in kernel/task_usermem.go.

  • Access to a task's virtual memory, from a context that is at or above the level of the kernel package, but where any of the above constraints does not hold (e.g. PTRACE_POKEDATA, which ignores application memory protections); obtain the task's mm.MemoryManager by calling kernel.Task.MemoryManager, and call its IO methods directly.

  • Access to a task's virtual memory, from a context that is below the level of the kernel package (e.g. filesystem I/O); clients must pass I/O arguments from higher layers, usually in the form of an IOSequence. The kernel.Task.SingleIOSequence and kernel.Task.IovecsIOSequence functions in kernel/task_usermem.go are convenience functions for doing so.