nfsd_selinux man page

nfsd_selinux — Security Enhanced Linux Policy for the nfsd processes

Description

Security-Enhanced Linux secures the nfsd processes via flexible mandatory access control.

The nfsd processes execute with the nfsd_t SELinux type. You can check if you have these processes running by executing the ps command with the -Z qualifier.

For example:

ps -eZ | grep nfsd_t

Entrypoints

The nfsd_t SELinux type can be entered via the nfsd_exec_t file type.

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

/usr/lib/systemd/system-generators/nfs.*, /usr/sbin/rpc.nfsd, /usr/sbin/rpc.mountd

Process Types

SELinux defines process types (domains) for each process running on the system

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

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

The following process types are defined for nfsd:

nfsd_t

Note: semanage permissive -a nfsd_t can be used to make the process type nfsd_t permissive. SELinux does not deny access to permissive process types, but the AVC (SELinux denials) messages are still generated.

Booleans

SELinux policy is customizable based on least access required. nfsd policy is extremely flexible and has several booleans that allow you to manipulate the policy and run nfsd with the tightest access possible.

If you want to allow any files/directories to be exported read/only via NFS, you must turn on the nfs_export_all_ro boolean. Enabled by default.

setsebool -P nfs_export_all_ro 1

If you want to allow any files/directories to be exported read/write via NFS, you must turn on the nfs_export_all_rw boolean. Enabled by default.

setsebool -P nfs_export_all_rw 1

If you want to allow users to resolve user passwd entries directly from ldap rather then using a sssd server, you must turn on the authlogin_nsswitch_use_ldap boolean. Disabled by default.

setsebool -P authlogin_nsswitch_use_ldap 1

If you want to allow all daemons to write corefiles to /, you must turn on the daemons_dump_core boolean. Disabled by default.

setsebool -P daemons_dump_core 1

If you want to enable cluster mode for daemons, you must turn on the daemons_enable_cluster_mode boolean. Enabled by default.

setsebool -P daemons_enable_cluster_mode 1

If you want to allow all daemons to use tcp wrappers, you must turn on the daemons_use_tcp_wrapper boolean. Disabled by default.

setsebool -P daemons_use_tcp_wrapper 1

If you want to allow all daemons the ability to read/write terminals, you must turn on the daemons_use_tty boolean. Disabled by default.

setsebool -P daemons_use_tty 1

If you want to deny any process from ptracing or debugging any other processes, you must turn on the deny_ptrace boolean. Enabled by default.

setsebool -P deny_ptrace 1

If you want to allow all domains to use other domains file descriptors, you must turn on the domain_fd_use boolean. Enabled by default.

setsebool -P domain_fd_use 1

If you want to allow all domains to have the kernel load modules, you must turn on the domain_kernel_load_modules boolean. Disabled by default.

setsebool -P domain_kernel_load_modules 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 enable reading of urandom for all domains, you must turn on the global_ssp boolean. Disabled by default.

setsebool -P global_ssp 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 confined applications to use nscd shared memory, you must turn on the nscd_use_shm boolean. Disabled by default.

setsebool -P nscd_use_shm 1

Port Types

SELinux defines port types to represent TCP and UDP ports.

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. SELinux nfsd policy is very flexible allowing users to setup their nfsd processes in as secure a method as possible.

The following port types are defined for nfsd:

nfs_port_t

Default Defined Ports: tcp 2049,20048-20049 udp 2049,20048-20049

Managed Files

The SELinux process type nfsd_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.

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

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

mount_var_run_t

/run/mount(/.*)?
/dev/.mount(/.*)?
/var/run/mount(/.*)?
/var/run/davfs2(/.*)?
/var/cache/davfs2(/.*)?

nfsd_fs_t

nfsd_unit_file_t

/usr/lib/systemd/system/nfs.*

public_content_rw_t

/var/spool/abrt-upload(/.*)?

root_t

/
/initrd

var_lib_nfs_t

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

var_lib_t

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

File Contexts

SELinux requires files to have an extended attribute to define the file type.

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

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

STANDARD FILE CONTEXT

SELinux defines the file context types for the nfsd, if you wanted to store files with these types in a diffent paths, you need to execute the semanage command to sepecify alternate labeling and then use restorecon to put the labels on disk.

semanage fcontext -a -t nfsd_unit_file_t '/srv/mynfsd_content(/.*)?'
restorecon -R -v /srv/mynfsd_content

Note: SELinux often uses regular expressions to specify labels that match multiple files.

The following file types are defined for nfsd:

nfsd_exec_t

- Set files with the nfsd_exec_t type, if you want to transition an executable to the nfsd_t domain.

Paths:
/usr/lib/systemd/system-generators/nfs.*, /usr/sbin/rpc.nfsd, /usr/sbin/rpc.mountd

nfsd_fs_t

- Set files with the nfsd_fs_t type, if you want to treat the files as nfsd fs data.

nfsd_initrc_exec_t

- Set files with the nfsd_initrc_exec_t type, if you want to transition an executable to the nfsd_initrc_t domain.

nfsd_unit_file_t

- Set files with the nfsd_unit_file_t type, if you want to treat the files as nfsd unit content.

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.

Sharing Files

If you want to share files with multiple domains (Apache, FTP, rsync, Samba), you can set a file context of public_content_t and public_content_rw_t. These context allow any of the above domains to read the content. If you want a particular domain to write to the public_content_rw_t domain, you must set the appropriate boolean.

Allow nfsd servers to read the /var/nfsd directory by adding the public_content_t file type to the directory and by restoring the file type.

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

Allow nfsd servers to read and write /var/nfsd/incoming by adding the public_content_rw_t type to the directory and by restoring the file type. You also need to turn on the nfsd_anon_write boolean.

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

If you want to allow nfs servers to modify public files used for public file transfer services. Files/Directories must be labeled public_content_rw_t., you must turn on the nfsd_anon_write boolean.

setsebool -P nfsd_anon_write 1

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 port can also be used to manipulate the port definitions

semanage boolean can also be used to manipulate the booleans

system-config-selinux is a GUI tool available to customize SELinux policy settings.

Author

This manual page was auto-generated using sepolicy manpage .

See Also

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

Info

16-12-07 nfsd SELinux Policy nfsd