I have no idea what is going on but this looks good. I agree with you guys. Upvoted.
this post was submitted on 05 Oct 2023
530 points (98.9% liked)
Linux
47369 readers
887 users here now
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
Rules
- Posts must be relevant to operating systems running the Linux kernel. GNU/Linux or otherwise.
- No misinformation
- No NSFW content
- No hate speech, bigotry, etc
Related Communities
Community icon by Alpár-Etele Méder, licensed under CC BY 3.0
founded 5 years ago
MODERATORS
Cool. Does ACL support also depend on the filesystem?
Yeah, but I think all reasonably-modern Unixy filesystems on Linux will support ACLs. ext2/3/4, btrfs, xfs, zfs, jfs, etc.
Yes. Some filesystems straight up do not support ACL of any kind (eg: fat32)
Fat32 doesn't support regular file permissions either, right? I was under the impression that it was permissionless.
You are entirely correct, it has no permission system to speak of
I'll speak of it anyway: There's a "Read-only" bit on every file/directory and The User (there's only one!) can change it for any of them at any time.
Technically, this is also possible by creating extra groups, but this kind of access control presumably exists because the old-school method can be a pain to administer. Choosing group names can also be an "interesting" secondary challenge.
i.e. Dude's not going to be best pleased if they ls -l and see the group on the file is xyzgroup-but-not-dude even if it is with good reason. (Shouldn't have deleted the database, dude.)
I don't really think that that's a realistic goal for ACLs. I mean, getfacl showing the user specifically being excluded probably isn't any more-polite.
I understand it all less after reading that. I need more coffee.
Confusing. You set a mask for a user and somehow it propagated down to a group and then you change permission on that group suddenly it applies to the user? Either something is wrong here or ACL permissions make absolutely zero sense. It is 5 billion times easier to use normal permissions to set these things up.
I think it's like this: what used to be group in regular permissions output is a union of group and ACL mask in ACL output. Mask sets the upper limit of what ACL can do, so if mask is rw- then it's impossible to set a r-x ACL permission because allowing execution is not allowed.
This seems to be more geared towards enterprise environment where it could be complicated to cleanly define groups, since you can only give access to one you might run into a problem where dept. A needs access to that directory but also person G from dept. B and person K from dept. C.
Yep, it's basically a way to define new groups per directory. But these groups are hidden from the normal group commands!
Does anybody use ACL without regretting it?
Whoaa, are you ACLing sober? Slow down champ!!
Cool, I didn't know ACLs were a widely available thing but the infographic explains pretty well! Sounds really useful when granular controls are needed, but I could also imagine it being a huge pain in environments already built out and scripted around regular permissions. Still as always, options are good and an ounce of planning is worth a pound of troubleshooting.
I do low-key hate seeing a directory named "dir" and a group named "me" though. That's chaotic neutral shit at the very least.
ACL Access-Control Lists
Access Control List Access Control Lists?
I mean in this case it's to show what ACL means, not like RIP in peace
That's what parentheses are for.
That's all fine and dandy, but why does it say rxw on the left?
Permissions are listed as "user", "group", "other". I.e. the user who made the file, the group of the user who made the file (usually just their name as a group), and everyone else. In this case the rxw is for the user.
For chmod, you can also represent these as binary numbers: 111 would mean having all 3, 101 would mean having read and write, etc. These binary numbers then get turned back into regular numbers (7 in the first example, since it's 111) for chmod. Giving a file "chmod 777" means the user, group, and other all have full permissions on the file. "chmod 700" gives the creator full control, but no one else can view, modify, or execute the file.
It's supposed to be rwx, not rxw.
Oh I completely missed that lol. Oh well, it's probably still a useful explanation for someone else reading this
I feel bad for you because you were just trying to help.
🤷♂️ They're just internet points, lemmy doesn't notify about up/downvotes so I will only see it if people respond. Either way it's hopefully still useful to someone else looking at the post who isn't familiar with basic permissions or acl
Bro made it in Excilidraw
it’s a really awesome website
Sudo
The only thing you need to know about file acls is not to use them. Similar thing can be said for Network ACLs to be honest.
I've been a network engineer for five years at three companies and not a one has used switch or router based ACL's. It's all in the FW appliance.
Network ACLs are my bane. Someone long ago decided we needed to "isolate" the network, so they put ACLs everywhere and so now 50% of my teams time is spend fucking with ACLs :/ It's awful.
Yeah don't get me wrong it's an excellent part of network security but if it's not defined primarily on one device it's a hassle.