prelink_selinux(8) SELinux Policy prelink prelink_selinux(8)NAMEprelink_selinux - Security Enhanced Linux Policy for the prelink pro‐
cesses
DESCRIPTION
Security-Enhanced Linux secures the prelink processes via flexible
mandatory access control.
The prelink processes execute with the prelink_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 prelink_t
ENTRYPOINTS
The prelink_t SELinux type can be entered via the filesystem_type,
unlabeled_t, proc_type, file_type, prelink_exec_t, sysctl_type,
mtrr_device_t file types.
The default entrypoint paths for the prelink_t domain are the follow‐
ing:
all files on the system, /usr/sbin/prelink(.bin)?, /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
prelink policy is very flexible allowing users to setup their prelink
processes in as secure a method as possible.
The following process types are defined for prelink:
prelink_cron_system_t, prelink_t
Note: semanage permissive -a prelink_t can be used to make the process
type prelink_t permissive. SELinux does not deny access to permissive
process types, but the AVC (SELinux denials) messages are still gener‐
ated.
BOOLEANS
SELinux policy is customizable based on least access required. prelink
policy is extremely flexible and has several booleans that allow you to
manipulate the policy and run prelink with the tightest access possi‐
ble.
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 bool‐
ean. 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 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 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 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 exe‐
cutable. 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 selinuxuser_exec‐
stack boolean. Enabled by default.
setsebool -P selinuxuser_execstack 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 prelink_cron_system_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
prelink_cron_system_t, you must turn on the kerberos_enabled boolean.
setsebool -P kerberos_enabled 1
MANAGED FILES
The SELinux process type prelink_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 prelink policy is very flexible allowing users to setup their
prelink processes in as secure a method as possible.
EQUIVALENCE DIRECTORIES
prelink policy stores data with multiple different file context types
under the /var/log/prelink directory. If you would like to store the
data in a different directory you can use the semanage command to cre‐
ate an equivalence mapping. If you wanted to store this data under the
/srv dirctory you would execute the following command:
semanage fcontext -a -e /var/log/prelink /srv/prelink
restorecon -R -v /srv/prelink
STANDARD FILE CONTEXT
SELinux defines the file context types for the prelink, 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 prelink_cache_t '/srv/prelink/content(/.*)?'
restorecon -R -v /srv/myprelink_content
Note: SELinux often uses regular expressions to specify labels that
match multiple files.
The following file types are defined for prelink:
prelink_cache_t
- Set files with the prelink_cache_t type, if you want to store the
files under the /var/cache directory.
prelink_cron_system_exec_t
- Set files with the prelink_cron_system_exec_t type, if you want to
transition an executable to the prelink_cron_system_t domain.
prelink_exec_t
- Set files with the prelink_exec_t type, if you want to transition an
executable to the prelink_t domain.
prelink_log_t
- Set files with the prelink_log_t type, if you want to treat the data
as prelink log data, usually stored under the /var/log directory.
Paths:
/var/log/prelink(/.*)?, /var/log/prelink.log.*
prelink_tmp_t
- Set files with the prelink_tmp_t type, if you want to store prelink
temporary files in the /tmp directories.
prelink_tmpfs_t
- Set files with the prelink_tmpfs_t type, if you want to store prelink
files on a tmpfs file system.
prelink_var_lib_t
- Set files with the prelink_var_lib_t type, if you want to store the
prelink files under the /var/lib directory.
Paths:
/var/lib/prelink(/.*)?, /var/lib/misc/prelink.*
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 data‐
base. 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 pol‐
icy modules.
semanage boolean can also be used to manipulate the booleans
system-config-selinux is a GUI tool available to customize SELinux pol‐
icy settings.
AUTHOR
This manual page was auto-generated using sepolicy manpage .
SEE ALSOselinux(8), prelink(8), semanage(8), restorecon(8), chcon(1), sepol‐
icy(8) , setsebool(8), prelink_cron_system_selinux(8), pre‐
link_cron_system_selinux(8)prelink 13-11-20 prelink_selinux(8)
