NAME¶

tftpd_selinux - Security Enhanced Linux Policy for the tftpd processes

DESCRIPTION¶

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

The tftpd processes execute with the tftpd_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 tftpd_t

ENTRYPOINTS¶

The tftpd_t SELinux type can be entered via the tftpd_exec_t file type.

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

/usr/sbin/atftpd, /usr/sbin/in.tftpd

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 ps

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

The following process types are defined for tftpd:

tftpd_t

Note: semanage permissive -a tftpd_t can be used to make the process type tftpd_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. tftpd policy is extremely flexible and has several booleans that allow you to manipulate the policy and run tftpd with the tightest access possible.

If you want to allow tftp to read and write files in the user home directories, you must turn on the tftp_home_dir boolean. Disabled by default.

setsebool -P tftp_home_dir 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 any process to mmap any file on system with attribute file_type, you must turn on the domain_can_mmap_files boolean. Enabled by default.

setsebool -P domain_can_mmap_files 1

If you want to allow all domains write to kmsg_device, while kernel is executed with systemd.log_target=kmsg parameter, you must turn on the domain_can_write_kmsg boolean. Disabled by default.

setsebool -P domain_can_write_kmsg 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

If you want to support ecryptfs home directories, you must turn on the use_ecryptfs_home_dirs boolean. Disabled by default.

setsebool -P use_ecryptfs_home_dirs 1

If you want to support fusefs home directories, you must turn on the use_fusefs_home_dirs boolean. Disabled by default.

setsebool -P use_fusefs_home_dirs 1

If you want to support NFS home directories, you must turn on the use_nfs_home_dirs boolean. Disabled 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

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

The following port types are defined for tftpd:

tftp_port_t

Default Defined Ports: udp 69

MANAGED FILES¶

The SELinux process type tftpd_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.

cifs_t

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

ecryptfs_t

/home/[^/]+/.Private(/.*)?
/home/[^/]+/.ecryptfs(/.*)?

fusefs_t

/var/run/user/[^/]*/gvfs

nfs_t

public_content_rw_t

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

root_t

/sysroot/ostree/deploy/.*-atomic.*/deploy(/.*)?
/
/initrd

tftpd_var_run_t

tftpdir_rw_t

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

user_home_type

all user home files

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 ls

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

STANDARD FILE CONTEXT

SELinux defines the file context types for the tftpd, 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 tftpdir_t '/srv/mytftpd_content(/.*)?'
restorecon -R -v /srv/mytftpd_content

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

The following file types are defined for tftpd:

tftpd_etc_t

- Set files with the tftpd_etc_t type, if you want to store tftpd files in the /etc directories.

tftpd_exec_t

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

Paths:

/usr/sbin/atftpd, /usr/sbin/in.tftpd

tftpd_var_run_t

- Set files with the tftpd_var_run_t type, if you want to store the tftpd files under the /run or /var/run directory.

tftpdir_rw_t

- Set files with the tftpdir_rw_t type, if you want to treat the files as tftpdir read/write content.

tftpdir_t

- Set files with the tftpdir_t type, if you want to treat the files as tftpdir data.

Paths:

/tftpboot/.*, /tftpboot

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 tftpd servers to read the /var/tftpd 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/tftpd(/.*)?"
restorecon -F -R -v /var/tftpd

Allow tftpd servers to read and write /var/tftpd/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 tftpd_anon_write boolean.

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

If you want to allow tftp to modify public files used for public file transfer services., you must turn on the tftp_anon_write boolean.

setsebool -P tftp_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), tftpd(8), semanage(8), restorecon(8), chcon(1), sepolicy(8) , setsebool(8)