Linux Permissions Flaws and Fixes

Linux Permissions Flaws and Fixes | Generated by AI

Home 2026.02

Question: What are unpopular ideas about Linux user/group/permission design?

Answer:

Here are some relatively unpopular or controversial takes on the classic Unix/Linux user/group/other permission model (often heard in sysadmin circles, security discussions, or old Unix-vs-modern-systems debates):

The owner permissions field is mostly redundant in modern multi-user systems — group permissions + ACLs could handle almost everything better.
The owner bit mostly exists for historical reasons (it predates groups). In practice many people argue that if you always put users in appropriate groups, the owner field rarely provides meaningful extra security — it just adds mental overhead.
Forcing every user to have a primary group (especially the default username==group convention) is unnecessary and mildly harmful.
Many people believe primary groups should be optional or default to something neutral like users/nogroup. The current design creates a lot of useless per-user groups that clutter /etc/group and lead to confusion about secondary vs primary membership.
The three-tier model (user/group/other) is elegant in theory but actively harmful in 202x environments.
It encourages bad habits (chmod 777, world-readable home directories, sudo everything) because expressing even slightly complex rules is painful without ACLs — and most people avoid ACLs because they’re “complicated” and non-portable. The model pretends to offer fine-grained control while actually pushing people toward overly coarse (and insecure) solutions.
Traditional Unix permissions are not particularly secure by modern standards — the whole system is more of a convenience filter than real access control.
A surprisingly large number of privilege escalations and container breakouts still happen via overly permissive files/directories. Some argue Linux’s reputation for being “secure by design” regarding permissions is overstated marketing.
Directories should have had separate execute and search permissions from the beginning (like some other systems experimented with).
The overloaded meaning of the ‘x’ bit on directories (both traversal + listing) creates endless confusion, especially for beginners and when trying to allow someone to access a known path without directory listing.
chmod o= (removing other permissions) should be the true default for home directories on desktop/multi-user systems — not 755/022 umask.
The current defaults expose far too much user data by design (dotfiles, configs, keys, browser data). Many consider this a historical artifact that’s actively bad for privacy in 202x.
The permission model actively discourages least-privilege thinking in application development.
Because it’s annoying to manage without ACLs or capabilities, many services end up running far too privileged (or people just use containers everywhere to escape the problem instead of fixing permissions).
Special bits (SUID/SGID) cause more security problems than they solve in 2025+.
A vocal minority believes almost all remaining SUID binaries should be removed or replaced with systemd capabilities / ambient capabilities / policykit-style mechanisms — the SUID design is fundamentally fragile.

Most Linux users and administrators defend the traditional model as “simple and proven”, so these views tend to be unpopular or get dismissed as over-engineering / ACL fanboyism.

References:

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