user_screen_selinux(8)

💅 user_screen_selinux(8) — the user_screen manual, bestie edition 🎀

okay so this page is from the user_screen manual, and it's literally all about the SELinux policy that keeps your user_screen processes in check. grab a snack, we're getting into it ✨

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✨ NAME ✨

user_screen_selinux — the Security Enhanced Linux Policy for the user_screen processes, and yes it's exactly as iconic as it sounds 🫶

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🌸 DESCRIPTION 🌸

so basically, Security-Enhanced Linux secures the user_screen processes via flexible mandatory access control. that's the whole vibe. 🦋

the user_screen processes execute with the user_screen_t SELinux type. wanna check if you've got these processes running? just run the ps command with the -Z qualifier, easy.

for example:

ps -eZ | grep user_screen_t

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🔥 ENTRYPOINTS 🔥

the user_screen_t SELinux type can be entered via the screen_exec_t file type. that's the door, that's the way in, periodt.

the default entrypoint paths for the user_screen_t domain are literally these:

/usr/bin/tmux, /usr/bin/screen

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👑 PROCESS TYPES 👑

SELinux defines process types (domains) for each process running on the system. iconic behaviour ngl.

you can see the context of a process using the -Z option to ps. simple as.

Policy governs the access confined processes have to files. the SELinux user_screen policy is very flexible — it's giving "let users set up their user_screen processes in as secure a method as possible". we love to see it. 💜

the following process types are defined for user_screen:

user_screen_t

Note: semanage permissive -a user_screen_t can be used to make the process type user_screen_t permissive. SELinux does not deny access to permissive process types, but the AVC (SELinux denials) messages are still generated. so like, it's chill about denying you, but it's still watching and taking notes 😭

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🎀 BOOLEANS 🎀

SELinux policy is customizable based on least access required. the user_screen policy is extremely flexible and has several booleans that let you manipulate the policy and run user_screen with the tightest access possible. main character energy fr fr.

if you want to allow all domains to execute in fips_mode, you must turn on the fips_mode boolean. Enabled by default.

setsebool -P fips_mode 1

if you want to allow system to run with NIS, you must turn on the nis_enabled boolean. Disabled by default.

setsebool -P nis_enabled 1

if you want to determine whether screen can use fsetid/setuid/setgid capability, you must turn on the screen_allow_session_sharing boolean. Disabled by default.

setsebool -P screen_allow_session_sharing 1

if you want to support NFS home directories, you must turn on the use_nfs_home_dirs boolean. Enabled by default.

setsebool -P use_nfs_home_dirs 1

if you want to support SAMBA home directories, you must turn on the use_samba_home_dirs boolean. Disabled by default.

setsebool -P use_samba_home_dirs 1

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🦋 MANAGED FILES 🦋

the SELinux process type user_screen_t can manage files labeled with the following file types. the paths listed are the default paths for these file types. heads up though — the processes UID still need to have DAC permissions, so like, don't skip that part 🙈

• faillog_t — this one covers:

/var/log/btmp.*
/run/faillock(/.*)?
/var/log/faillog.*
/var/log/tallylog.*

• initrc_var_run_t — this one covers:

/run/sysconfig(/.*)?
/run/utmp
/run/keymap
/run/numlock-on
/run/setleds-on
/run/runlevel.dir
/run/setmixer_flag
/run/bootsplashctl

• krb5_host_rcache_t — this one covers:

/var/tmp/krb5_0.rcache2
/var/cache/krb5rcache(/.*)?
/var/tmp/nfs_0
/var/tmp/DNS_25
/var/tmp/host_0
/var/tmp/imap_0
/var/tmp/HTTP_23
/var/tmp/HTTP_48
/var/tmp/ldap_55
/var/tmp/ldap_487
/var/tmp/ldapmap1_0

• user_tmp_type — literally all user tmp files 💀

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💖 COMMANDS 💖

semmanage... no wait, semanage fcontext can also be used to manipulate default file context mappings. slay.

semanage permissive can also be used to manipulate whether or not a process type is permissive. also slay.

semanage module can also be used to enable/disable/install/remove policy modules. more slay.

semanage boolean can also be used to manipulate the booleans. you see the pattern here 👑

system-config-selinux is a GUI tool available to customize SELinux policy settings. for the visual learners out there, we got you. ✨

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🌈 AUTHOR 🌈

This manual page was auto-generated using sepolicy manpage. so nobody hand-wrote it, it just kind of manifested itself and honestly? ate. 💅

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🌸 SEE ALSO 🌸

selinux(8), user_screen(8), semanage(8), restorecon(8), chcon(1), sepolicy(8), setsebool(8)

go read them, iykyk 🫶

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okay that's the whole page bestie 💖 this was user_screen (the manual name, cute right), from source user_screen_selinux(8), dated 26-10-06 — go forth, run your screen sessions, and remember: highkey iconic, lowkey secure. 🎀✨🌺