Security-Enhanced Linux secures the firstboot processes via flexible mandatory access control.
The firstboot processes execute with the firstboot_t SELinux type. You can check if you have these processes running by executing the ps command with the -Z qualifier.
ps -eZ | grep firstboot_t
The firstboot_t SELinux type can be entered via the firstboot_exec_t file type.
The default entrypoint paths for the firstboot_t domain are the following:
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 firstboot policy is very flexible allowing users to setup their firstboot processes in as secure a method as possible.
The following process types are defined for firstboot:
Note: semanage permissive -a firstboot_t can be used to make the process type firstboot_t permissive. SELinux does not deny access to permissive process types, but the AVC (SELinux denials) messages are still generated.
SELinux policy is customizable based on least access required. firstboot policy is extremely flexible and has several booleans that allow you to manipulate the policy and run firstboot with the tightest access possible.
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 control the ability to mmap a low area of the address space, as configured by /proc/sys/vm/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 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 selinuxuser_execheap boolean. Disabled by default.
setsebool -P selinuxuser_execheap 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 selinuxuser_execstack boolean. Enabled by default.
setsebool -P selinuxuser_execstack 1
The SELinux process type firstboot_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.
all files on the system
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 firstboot policy is very flexible allowing users to setup their firstboot processes in as secure a method as possible.
STANDARD FILE CONTEXT
SELinux defines the file context types for the firstboot, if you wanted to store files with these types in a diffent paths, you need to execute the semanage command to specify alternate labeling and then use restorecon to put the labels on disk.
semanage fcontext -a -t firstboot_exec_t '/srv/firstboot/content(/.*)?'
restorecon -R -v /srv/myfirstboot_content
Note: SELinux often uses regular expressions to specify labels that match multiple files.
The following file types are defined for firstboot:
- Set files with the firstboot_etc_t type, if you want to store firstboot files in the /etc directories.
- Set files with the firstboot_exec_t type, if you want to transition an executable to the firstboot_t domain.
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.
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.
This manual page was auto-generated using sepolicy manpage .
selinux(8), firstboot(8), semanage(8), restorecon(8), chcon(1), sepolicy(8), setsebool(8)