smbd_selinux(8)

💅 smbd_selinux(8) — SELinux Policy for smbd

okay bestie, so this is the smbd_selinux(8) page, and it's literally the whole glow-up guide for how SELinux babysits your smbd processes. grab a strawberry drink 🍓 and let's get into it.

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✨ NAME ✨

smbd_selinux — the Security Enhanced Linux Policy for the smbd processes, and yes it's as iconic as it sounds 👑

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🌸 DESCRIPTION 🌸

Security-Enhanced Linux secures the smbd processes via flexible mandatory access control. no cap, that's the whole vibe — SELinux is the bouncer at the club and smbd is NOT getting in anywhere it wasn't invited.

The smbd processes execute with the smbd_t SELinux type. you can check if you have these processes running by executing the ps command with the -Z qualifier — that -Z is the main character flag, it shows you the security context, iykyk 🦋

for example:

ps -eZ | grep smbd_t

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🚪 ENTRYPOINTS 🚪

The smbd_t SELinux type can be entered via the smbd_exec_t file type. that's the door, fr fr.

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

/usr/bin/smbd

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👑 PROCESS TYPES 👑

SELinux defines process types (domains) for each process running on the system. think of a domain as a little outfit each process puts on before it's allowed to go anywhere ✨

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

Policy governs the access confined processes have to files. the SELinux smbd policy is very flexible, allowing users to setup their smbd processes in as secure a method as possible.

The following process types are defined for smbd:

smbd_t

Note: semanage permissive -a smbd_t can be used to make the process type smbd_t permissive. SELinux does not deny access to permissive process types, BUT the AVC (SELinux denials) messages are still generated. so it's like, it'll let things slide but it's still gonna text everyone about it 💀

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🎀 BOOLEANS 🎀

SELinux policy is customizable based on least access required. the smbd policy is extremely flexible and has several booleans that allow you to manipulate the policy and run smbd with the tightest access possible. booleans are basically little on/off switches and honestly they ate 🔥

If you want to dontaudit all daemons scheduling requests (setsched, sys_nice), you must turn on the daemons_dontaudit_scheduling boolean. Enabled by default.

setsebool -P daemons_dontaudit_scheduling 1

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 confined applications to run with kerberos, you must turn on the kerberos_enabled boolean. Enabled by default.

setsebool -P kerberos_enabled 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 allow samba to create new home directories (e.g. via PAM), you must turn on the samba_create_home_dirs boolean. Disabled by default.

setsebool -P samba_create_home_dirs 1

If you want to allow samba to act as the domain controller, add users, groups and change passwords, you must turn on the samba_domain_controller boolean. Disabled by default.

setsebool -P samba_domain_controller 1

If you want to allow samba and winbind-rpcd to share users home directories, you must turn on the samba_enable_home_dirs boolean. Disabled by default.

setsebool -P samba_enable_home_dirs 1

If you want to allow samba to share any file/directory read only, you must turn on the samba_export_all_ro boolean. Disabled by default.

setsebool -P samba_export_all_ro 1

If you want to allow samba to share any file/directory read/write, you must turn on the samba_export_all_rw boolean. Disabled by default.

setsebool -P samba_export_all_rw 1

If you want to allow smbd to load libgfapi from gluster, you must turn on the samba_load_libgfapi boolean. Disabled by default.

setsebool -P samba_load_libgfapi 1

If you want to allow samba to act as a portmapper, you must turn on the samba_portmapper boolean. Disabled by default.

setsebool -P samba_portmapper 1

If you want to allow samba to run unconfined scripts, you must turn on the samba_run_unconfined boolean. Disabled by default.

setsebool -P samba_run_unconfined 1

If you want to allow samba to export ntfs/fusefs volumes, you must turn on the samba_share_fusefs boolean. Disabled by default.

setsebool -P samba_share_fusefs 1

If you want to allow samba to export NFS volumes, you must turn on the samba_share_nfs boolean. Disabled by default.

setsebool -P samba_share_nfs 1

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🔌 PORT TYPES 🔌

SELinux defines port types to represent TCP and UDP ports. yes babe, ports have types too, everyone's got a label 💅

You can see the types associated with a port by using the following command:

semanage port -l

Policy governs the access confined processes have to these ports. the SELinux smbd policy is very flexible, allowing users to setup their smbd processes in as secure a method as possible.

The following port types are defined for smbd:

smbd_port_t

Default Defined Ports:

tcp 445,137-139

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📂 MANAGED FILES 📂

The SELinux process type smbd_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 not out here doing DAC's job, it's giving teamwork 🫶

auth_cache_t

/var/cache/coolkey(/.*)?

cluster_conf_t

/etc/cluster(/.*)?

cluster_var_lib_t

/var/lib/pcsd(/.*)?
/var/lib/cluster(/.*)?
/var/lib/openais(/.*)?
/var/lib/pengine(/.*)?
/var/lib/corosync(/.*)?
/usr/lib/heartbeat(/.*)?
/var/lib/heartbeat(/.*)?
/var/lib/pacemaker(/.*)?

cluster_var_run_t

/run/crm(/.*)?
/run/cman_.*
/run/rsctmp(/.*)?
/run/aisexec.*
/run/heartbeat(/.*)?
/run/pcsd-ruby.socket
/run/corosync-qnetd(/.*)?
/run/corosync-qdevice(/.*)?
/run/pcsd.socket
/run/corosync.pid
/run/cpglockd.pid
/run/rgmanager.pid
/run/cluster/rgmanager.sk

ctdbd_var_lib_t

/var/lib/ctdb(/.*)?
/var/lib/ctdbd(/.*)?

faillog_t

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

fusefs_t

/run/user/[0-9]+/gvfs

glusterd_var_lib_t

/var/lib/glusterd(/.*)?

glusterd_var_run_t

/run/gluster(/.*)?
/run/glusterd.*
/run/glusterd.*
/run/glusterd(/.*)?

httpd_user_content_t

/home/[^/]+/((www)|(web)|(public_html))(/.+)?

initrc_var_run_t

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

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

nfs_t

nmbd_var_run_t

/run/nmbd(/.*)?
/run/samba/nmbd(/.*)?
/run/samba/nmbd.pid
/run/samba/messages.tdb
/run/samba/namelist.debug
/run/samba/unexpected.tdb

non_security_file_type

noxattrfs

all files on file systems which do not support extended attributes

root_t

/sysroot/.aleph-version.json
/sysroot/ostree/deploy/.*-atomic/deploy(/.*)?
/
/initrd
/var/lib/ntp

samba_log_t

/var/log/samba(/.*)?

samba_secrets_t

/etc/samba/smbpasswd
/etc/samba/passdb.tdb
/etc/samba/MACHINE.SID
/etc/samba/secrets.tdb

samba_share_t

use this label for random content that will be shared using samba

samba_spool_t

/var/spool/samba(/.*)?

security_t

/selinux

smbd_tmp_t

smbd_tmpfs_t

smbd_var_run_t

/run/samba(/.*)?
/run/samba/smbd.pid
/run/samba/brlock.tdb
/run/samba/locking.tdb
/run/samba/gencache.tdb
/run/samba/sessionid.tdb
/run/samba/share_info.tdb
/run/samba/connections.tdb

user_home_type

all user home files

wtmp_t

/var/log/wtmp.*

wtmpdb_journal_t

/var/lib/wtmpdb/wtmp.db-journal

wtmpdb_t

/var/lib/wtmpdb(/.*)?

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🗂️ FILE CONTEXTS 🗂️

SELinux requires files to have an extended attribute to define the file type. every file needs its little name tag, periodt 🎀

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

Policy governs the access confined processes have to these files. the SELinux smbd policy is very flexible, allowing users to setup their smbd processes in as secure a method as possible.

⭐ STANDARD FILE CONTEXT ⭐

SELinux defines the file context types for the smbd. if you wanted to store files with these types in a different paths, you need to execute the semanage command to specify alternate labeling and then use restorecon to put the labels on disk. relabeling is literally just giving your files a makeover ✨

semanage fcontext -a -t smbd_exec_t '/srv/smbd/content(/.*)?'
restorecon -R -v /srv/mysmbd_content

Note: SELinux often uses regular expressions to specify labels that match multiple files. regex is that girl, lowkey.

The following file types are defined for smbd:

• smbd_exec_t — set files with the smbd_exec_t type, if you want to transition an executable to the smbd_t domain.
• smbd_keytab_t — set files with the smbd_keytab_t type, if you want to treat the files as kerberos keytab files.
• smbd_tmp_t — set files with the smbd_tmp_t type, if you want to store smbd temporary files in the /tmp directories.
• smbd_tmpfs_t — set files with the smbd_tmpfs_t type, if you want to store smbd files on a tmpfs file system.
• smbd_var_run_t — set files with the smbd_var_run_t type, if you want to store the smbd files under the /run or /var/run directory.

Paths:

/run/samba(/.*)?, /run/samba/smbd.pid, /run/samba/brlock.tdb,
/run/samba/locking.tdb, /run/samba/gencache.tdb,
/run/samba/sessionid.tdb, /run/samba/share_info.tdb,
/run/samba/connections.tdb

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. chcon is the temporary tattoo, semanage fcontext + restorecon is the real ink 💀

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(to be continued bestie, there's more 💖)

🌈 SHARING FILES 🌈

Okay bestie, say you wanna share files with multiple domains — like Apache, FTP, rsync, and Samba all up in the mix. You can set a file context of public_content_t and public_content_rw_t. These contexts let any of those domains read the content. If you want one particular domain to write to the public_content_rw_t domain, you must set the appropriate boolean. No cap. 💅

Wanna let smbd servers read the /var/smbd directory? Add the public_content_t file type to the directory and restore the file type. Easy:

semanage fcontext -a -t public_content_t "/var/smbd(/.*)?"
restorecon -F -R -v /var/smbd

Wanna let smbd servers read and write /var/smbd/incoming? Add the public_content_rw_t type to the directory and restore the file type. You also need to turn on the smbd_anon_write boolean. Two-step slay:

semanage fcontext -a -t public_content_rw_t "/var/smbd/incoming(/.*)?"
restorecon -F -R -v /var/smbd/incoming
setsebool -P smbd_anon_write 1

And if you want to allow samba to modify public files used for public file transfer services — note that Files/Directories must be labeled public_content_rw_t. — then you must turn on the smbd_anon_write boolean:

setsebool -P smbd_anon_write 1

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💻 COMMANDS 💻

These tools are your little helpers, bestie:

• semanage fcontext — can also be used to manipulate default file context mappings. Iconic.
• 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 port — can also be used to manipulate the port definitions.
• semanage boolean — can also be used to manipulate the booleans.
• system-config-selinux — a GUI tool available to customize SELinux policy settings. GUI girlies rise 🫶

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👑 AUTHOR 👑

This manual page was auto-generated using sepolicy manpage. Respect the automation, honestly. ✨

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🔗 SEE ALSO 🔗

Go read these next, bestie — they’re giving required reading:

• selinux(8)
• smbd(8)
• semanage(8)
• restorecon(8)
• chcon(1)
• sepolicy(8)
• setsebool(8)

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That’s the whole page, bestie 🫶 — source smbd, version/date 26-10-06, page smbd_selinux(8). Periodt. 💅🎀