procps

May 31, 2017Craig 1 Comment

The sudo tty bug and procps

There have been recent reports of a security bug in sudo (CVE-2017-1000367) where you can fool sudo into thinking what controlling terminal it is running on to bypass its security checks. One of the first things I thought of was, is procps vulnerable to the same bug? Sure, it wouldn’t be a security bypass, but it would be a normal sort of bug. A lot of programs in procps have a concept of a controlling terminal, or the TTY field for either viewing or filtering, could they be fooled into thinking the process had a different controlling terminal?

Was I going to be in the same pickle as the sudo maintainers? The meat between the stat parsing sandwich? Can I find any more puns related somehow to the XKCD comic?

TLDR: No.

procps 3.3.12

The procps developers are happy to announce that version 3.3.12 of procps was released today. This version has a mixture of bug fixes and enhancements. This unfortunately means another API bump but we are hoping this will be fixed with the new library API coming soon.

procps is developed on gitlab and the new version of procps can be found at https://gitlab.com/procps-ng/procps/tree/newlib

procps 3.3.12 can be found at https://gitlab.com/procps-ng/procps/tags/v3.3.12

Displaying Linux Memory

Memory management is hard, but RAM management may be even harder.

Most people know the vague overall concept of how memory usage is displayed within Linux. You have your total memory which is everything inside the box; then there is used and free which is what the system is or is not using respectively. Some people might know that not all used is used and some of it actually is free. It can be very confusing to understand, even for a someone who maintains procps (the package that contains top and free, two programs that display memory usage).

So, how does the memory display work?

ps standards and locales

I looked at two interesting issues today around the ps program in the procps project. One had a solution and the other I’m puzzled about.

ps User-defined Format

Issue #9 was quite the puzzle. The output of ps changed depending if a different option had a hyphen before it or not.

First, the expected output

$ ps p $$ -o pid=pid,comm=comm
 pid comm
31612 bash

Next, the unusual output.

$ ps -p $$ -o pid=pid,comm=comm
pid,comm=comm
 31612

procps 3.3.11

I have updated NEWS, bumped the API and tagged in git; procps version 3.3.11 is now released!

This release we have fixed many bugs and made procps more robust for those odd corner cases. See the NEWS file for details. The most significant new feature in this release is the support for LXC containers in both ps and top.

The source files can be found at both sourceforge and gitlab at:

My thanks to the procps co-maintainers, bug reporters and merge/patch authors.

What’s Next?

There has been a large amount of work on the library API. This is not visible to this release as it is on a different git branch called newlib. The library is getting a complete overhaul and will look completely different to the old libproc/libprocps set. A decision hasn’t been made when newlib branch will merge into master, but we will do it once we’re happy the library and its API have settled. This change will be the largest change to procps’ library in its 20-odd year history but will mean the library will use common modern practices for libraries.