oomd VS systemd

OOMKiller has a bunch of issues. Its heuristics don't apply well across the wide range of workloads Linux provides (webserver? Database server? build server? desktop client? Gaming machine?), each of which would require its own tuning. (random example: https://lwn.net/Articles/761118/)

That's why some orgs implemented their own solutions to avoid OOMKiller having to enter the picture, like Facebook's user-space oomd: https://github.com/facebookincubator/oomd

I use paru to install/update the softwares on my laptop. I usually update the system twice per week. But recently I've noticed that oomd-git package was showing in the AUR updates everytime I ran the paru command. So, I checked the upstream URL but the main branch shows no new commits since last month. I have no idea why is this happening and weather it's a paru issue or oomd-git issue.

Additionally, you might want to check this: https://github.com/facebookincubator/oomd

I think the distinction is that MemoryMax= is just an interface to the cgroupv2 setting, i.e., that rule is implemented inside the kernel and invokes the kernel's OOM killer within a cgroup. The manpage for systemd-oomd says, "systemd-oomd is a system service that uses cgroups-v2 and pressure stall information (PSI) to monitor and take action on processes before an OOM occurs in kernel space."

It looks like systemd-oomd is related to (based on? from the same people as?) Facebook's oomd https://github.com/facebookincubator/oomd , whose documentation gives a bunch of reasons as to why you would prefer a userspace oomd that takes in PSI data and can be configured to proactively kill misbehaving processes instead of just letting the kernel OOM killer handle it. The major reason is time to recovery: a misbehaving process can cause a system to be so far under pressure that the kernel OOM killer will take a long time to flush things out, but a userspace component can respond in advance with more configurable rules (and more flexibility, since the kernel doesn't believe you're at capacity yet).

oomd - developed by facebook and will be default in Fedora 34, it is part of Systemd 247 but still in experimental stage

No, the OP was not sent any harassment, the OP _did_ the harassment as it can be seen in the tweets. I mean, they are right there, just click on the links you shared. One of the OP's followers even openly called for the assassination of the project maintainer, and you have the galls to defend him? This is truly deranged stuff.

And again, there is no "vulnerability", there is simply a person that doesn't know how Linux works and has learned something new. Which again it's fine, nobody knows everything and we all learn new things everyday, it's just that normal and sensible people don't use that to make grand claims on social media and start harassment campaigns culminating in death threats.

Professional security researchers responsibly report real issues using the appropriate channels, such as defined at: https://github.com/systemd/systemd/security/policy this is not the work of a researcher, this is a grifter looking for self-promotion on social media.

> 3. even `adduser` will not allow it by default

5. useradd does allow it (as noted in a comment). 6. Local users are not the only source, there things like LDAP and AD.

7. POSIX allows it:

* https://github.com/systemd/systemd/issues/6237#issuecomment-...

> I for one love to type out 13 extra characters

FWIW, systemd is normally pretty good at providing autocomplete suggestions, so even if you don't want to set up an alias you'll probably just have to type `--b ` to set it.

> I wonder what random ASCII escape sequences we can send.

According to the man page source[0]:

> The color specified should be an ANSI X3.64 SGR background color, i.e. strings such as `40`, `41`, …, `47`, `48;2;…`, `48;5;…`

and a link to the relevant Wikipedia page[1]. Given systemd's generally decent track record wrt defects and security issues, and the simplicity of valid colour values, I expect there's a fairly robust parameter verifier in there.

In fact, given the focus on starting the elevated command in a highly controlled environment, I'd expect the colour codes to be output to the originating terminal, not forwarded to the secure pty. That way, the only thing malformed escapes can affect is your own process, which you already have full control over anyway.

(Happy to be shown if that's a mistaken expectation though.)

[0] https://github.com/systemd/systemd/blob/main/man/run0.xml

[1] https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_G...

bash & zsh are supported by upstream: https://github.com/systemd/systemd/tree/main/shell-completio...

the right person to replace sudo, not: https://github.com/systemd/systemd/issues/6237

PS: https://pwnies.com/systemd-bugs/

https://github.com/systemd/systemd/issues/32028#issuecomment...

There are some very compelling arguments made there if you care to read them

Maybe it was because you weren't pointing out anything new?

There was a pull request to stop linking libzma to systemd before the attack even took place

https://github.com/systemd/systemd/pull/31550

This was likely one of many things that pushed the attackers to work faster, and forced them into making mistakes.

The PR for changing compression libraries to use dlopen() was opened several weeks before the xz-utils backdoor was revealed.

https://github.com/systemd/systemd/pull/31550