postfix_smtpd_selinux(8)

👑 postfix_smtpd_selinux — the SELinux glow-up for postfix_smtpd 💅

Okay bestie, buckle up. We're talking about postfix_smtpd_selinux, which is the Security Enhanced Linux Policy for the postfix_smtpd processes. Yeah, it's giving very much "the bodyguard your mail server didn't know it needed." 🫶

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🌸 NAME

postfix_smtpd_selinux — Security Enhanced Linux Policy for the postfix_smtpd processes. Periodt. 💖

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✨ DESCRIPTION

Security-Enhanced Linux secures the postfix_smtpd processes via flexible mandatory access control. Lowkey iconic, ngl. 🛡️

The postfix_smtpd processes execute with the postfix_smtpd_t SELinux type. Wanna check if you've got these processes running? Just execute the ps command with the -Z qualifier. Easy peasy.

For example:

ps -eZ | grep postfix_smtpd_t

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🚪 ENTRYPOINTS

The postfix_smtpd_t SELinux type can be entered via the postfix_smtpd_exec_t file type. It's like the VIP door into the domain. 🎟️

The default entrypoint paths for the postfix_smtpd_t domain are the following:

/usr/libexec/postfix/smtpd

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🧬 PROCESS TYPES

SELinux defines process types (domains) for each process running on the system. So yes, every process gets its own little label. We love organized chaos. 🎀

You can see the context of a process using the -Z option to ps.

Policy governs the access confined processes have to files. SELinux postfix_smtpd policy is very flexible, allowing users to setup their postfix_smtpd processes in as secure a method as possible. Flexibility and security? We love a dual-threat. ✨

The following process types are defined for postfix_smtpd:

• postfix_smtp_t
• postfix_smtpd_t

Note: semanage permissive -a postfix_smtpd_t can be used to make the process type postfix_smtpd_t permissive. SELinux does not deny access to permissive process types, but the AVC (SELinux denials) messages are still generated. So like, it's cool with it but it's still gonna gossip about it in the logs. 💀

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🎛️ BOOLEANS

SELinux policy is customizable based on least access required. postfix_smtpd policy is extremely flexible and has several booleans that allow you to manipulate the policy and run postfix_smtpd with the tightest access possible. It's giving "customizable but make it secure." 💖

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

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📂 MANAGED FILES

The SELinux process type postfix_smtpd_t can manage files labeled with the following file types. The paths listed are the default paths for these file types. Note: the processes UID still need to have DAC permissions. SELinux is powerful, but it's not that powerful, bestie. 🙈

krb5_host_rcache_t

/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

postfix_prng_t

/etc/postfix/prng_exch

postfix_smtpd_tmp_t

(no specific paths listed, it's just vibing in the /tmp directories 🫧)

postfix_spool_t

/var/spool/postfix.*
/var/spool/postfix/defer(/.*)?
/var/spool/postfix/flush(/.*)?
/var/spool/postfix/deferred(/.*)?
/var/spool/postfix/maildrop(/.*)?

postfix_var_run_t

/var/spool/postfix/pid/.*

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🏷️ FILE CONTEXTS

SELinux requires files to have an extended attribute to define the file type. It's literally in the file's DNA. 🧬

You can see the context of a file using the -Z option to ls.

Policy governs the access confined processes have to these files. SELinux postfix_smtpd policy is very flexible, allowing users to setup their postfix_smtpd processes in as secure a method as possible. (Yes, we said it again, because it's important and it slays.) ✨

STANDARD FILE CONTEXT

SELinux defines the file context types for postfix_smtpd. If you wanted to store files with these types in different paths, you need to execute the semanage command to specify alternate labeling and then use restorecon to put the labels on disk.

semanage fcontext -a -t postfix_smtpd_exec_t '/srv/postfix_smtpd/content(/.*)?'
restorecon -R -v /srv/mypostfix_smtpd_content

Note: SELinux often uses regular expressions to specify labels that match multiple files. Regex? In my SELinux? It's more likely than you think. 😭

The following file types are defined for postfix_smtpd:

postfix_smtpd_exec_t

• Set files with the postfix_smtpd_exec_t type, if you want to transition an executable to the postfix_smtpd_t domain.

postfix_smtpd_tmp_t

• Set files with the postfix_smtpd_tmp_t type, if you want to store postfix smtpd temporary files in the /tmp directories.

Note: File context can be temporarily modified with the chcon command. If you want to permanently change the file context you need to use the semanage fcontext command. This will modify the SELinux labeling database. You will need to use restorecon to apply the labels. So like, chcon is a quick touch-up, semanage fcontext is the full glow-up. 💅

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🛠️ COMMANDS

semanage fcontext can also be used to manipulate default file context mappings.

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

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

semanage boolean can also be used to manipulate the booleans.

system-config-selinux is a GUI tool available to customize SELinux policy settings. For the besties who prefer a lil clicky-clicky. 🖱️✨

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✍️ AUTHOR

This manual page was auto-generated using sepolicy manpage. The robots did the typing, we just added the sparkle. 🤖💖

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🔗 SEE ALSO

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

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That's the whole page, bestie! You're now fully caught up on the SELinux policy for postfix_smtpd. Go forth and be secure. 💜

This gem was served fresh from the 26-10-06 drop, brought to you by postfix_smtpd_selinux(8). Stay slay, keep your labels tight, and may your AVCs always be intentional. 🫶💖🎀