crond_selinux(8) SELinux Policy crond crond_selinux(8)
NAME
crond_selinux - Security Enhanced Linux Policy for the crond processes
DESCRIPTION
Security-Enhanced Linux secures the crond processes via flexible mandatory access control.
The crond processes execute with the crond_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 crond_t
ENTRYPOINTS
The crond_t SELinux type can be entered via the unlabeled_t, proc_type, file_type, crond_exec_t, mtrr_device_t, filesystem_type,
sysctl_type file types.
The default entrypoint paths for the crond_t domain are the following:
all files on the system, /usr/sbin/cron(d)?, /usr/sbin/atd, /usr/sbin/fcron, /dev/cpu/mtrr
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 crond policy is very flexible allowing users to setup their crond pro-
cesses in as secure a method as possible.
The following process types are defined for crond:
crond_t
Note: semanage permissive -a crond_t can be used to make the process type crond_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. crond policy is extremely flexible and has several booleans that allow you
to manipulate the policy and run crond with the tightest access possible.
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 authlo-
gin_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 user domains applications to map a memory region as both executable and writable, this is dangerous and the executable
should be reported in bugzilla, you must turn on the deny_execmem boolean. Enabled by default.
setsebool -P deny_execmem 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 enable extra rules in the cron domain to support fcron, you must turn on the fcron_crond boolean. Disabled by default.
setsebool -P fcron_crond 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 control the ability to mmap a low area of the address space, as configured by /proc/sys/kernel/mmap_min_addr, you must turn
on the mmap_low_allowed boolean. Disabled by default.
setsebool -P mmap_low_allowed 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. Enabled by default.
setsebool -P nscd_use_shm 1
If you want to enable polyinstantiated directory support, you must turn on the polyinstantiation_enabled boolean. Disabled by default.
setsebool -P polyinstantiation_enabled 1
If you want to disable kernel module loading, you must turn on the secure_mode_insmod boolean. Enabled by default.
setsebool -P secure_mode_insmod 1
If you want to boolean to determine whether the system permits loading policy, setting enforcing mode, and changing boolean values. Set
this to true and you have to reboot to set it back, you must turn on the secure_mode_policyload boolean. Enabled by default.
setsebool -P secure_mode_policyload 1
If you want to allow unconfined executables to make their heap memory executable. Doing this is a really bad idea. Probably indicates a
badly coded executable, but could indicate an attack. This executable should be reported in bugzilla, you must turn on the selin-
uxuser_execheap boolean. Disabled by default.
setsebool -P selinuxuser_execheap 1
If you want to allow all unconfined executables to use libraries requiring text relocation that are not labeled textrel_shlib_t, you must
turn on the selinuxuser_execmod boolean. Enabled by default.
setsebool -P selinuxuser_execmod 1
If you want to allow unconfined executables to make their stack executable. This should never, ever be necessary. Probably indicates a
badly coded executable, but could indicate an attack. This executable should be reported in bugzilla, you must turn on the selin-
uxuser_execstack boolean. Enabled by default.
setsebool -P selinuxuser_execstack 1
If you want to allow a user to login as an unconfined domain, you must turn on the unconfined_login boolean. Enabled by default.
setsebool -P unconfined_login 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
If you want to support X userspace object manager, you must turn on the xserver_object_manager boolean. Enabled by default.
setsebool -P xserver_object_manager 1
If you want to allow ZoneMinder to run su/sudo, you must turn on the zoneminder_run_sudo boolean. Disabled by default.
setsebool -P zoneminder_run_sudo 1
NSSWITCH DOMAIN
If you want to allow users to resolve user passwd entries directly from ldap rather then using a sssd server for the crond_t, you must turn
on the authlogin_nsswitch_use_ldap boolean.
setsebool -P authlogin_nsswitch_use_ldap 1
If you want to allow confined applications to run with kerberos for the crond_t, you must turn on the kerberos_enabled boolean.
setsebool -P kerberos_enabled 1
MANAGED FILES
The SELinux process type crond_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.
file_type
all files on the system
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 crond policy is very flexible allowing users to setup their
crond processes in as secure a method as possible.
STANDARD FILE CONTEXT
SELinux defines the file context types for the crond, 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 crond_exec_t '/srv/crond/content(/.*)?'
restorecon -R -v /srv/mycrond_content
Note: SELinux often uses regular expressions to specify labels that match multiple files.
The following file types are defined for crond:
crond_exec_t
- Set files with the crond_exec_t type, if you want to transition an executable to the crond_t domain.
Paths:
/usr/sbin/cron(d)?, /usr/sbin/atd, /usr/sbin/fcron
crond_initrc_exec_t
- Set files with the crond_initrc_exec_t type, if you want to transition an executable to the crond_initrc_t domain.
crond_tmp_t
- Set files with the crond_tmp_t type, if you want to store crond temporary files in the /tmp directories.
crond_unit_file_t
- Set files with the crond_unit_file_t type, if you want to treat the files as crond unit content.
Paths:
/usr/lib/systemd/system/atd.*, /usr/lib/systemd/system/crond.*
crond_var_run_t
- Set files with the crond_var_run_t type, if you want to store the crond files under the /run or /var/run directory.
Paths:
/var/run/.*cron.*, /var/run/crond?.pid, /var/run/crond?.reboot, /var/run/atd.pid, /var/run/fcron.pid, /var/run/fcron.fifo,
/var/run/anacron.pid
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.
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.
AUTHOR
This manual page was auto-generated using sepolicy manpage .
SEE ALSO
selinux(8), crond(8), semanage(8), restorecon(8), chcon(1), sepolicy(8) , setsebool(8)
crond 14-06-10 crond_selinux(8)