selinux: Add a secure_mode_setbool Boolean.

Enabling this will disable all permissions for setting SELinux Booleans,
even for unconfined domains.

This does not affect setenforce.  Enable secure_mode_policyload along with
secure_mode_setbool to fully lock the SELinux security interface.

Signed-off-by: Chris PeBenito <pebenito@ieee.org>
This commit is contained in:
Chris PeBenito 2021-03-05 16:06:44 -05:00
parent 1167739da1
commit 3ab2274e3d
2 changed files with 36 additions and 13 deletions

View File

@ -392,14 +392,18 @@ interface(`selinux_read_policy',`
interface(`selinux_set_generic_booleans',`
gen_require(`
type security_t;
bool secure_mode_setbool;
')
dev_search_sysfs($1)
allow $1 security_t:dir list_dir_perms;
allow $1 security_t:file rw_file_perms;
allow $1 security_t:file read_file_perms;
if(!secure_mode_setbool) {
allow $1 security_t:file write_file_perms;
allow $1 security_t:security setbool;
}
')
########################################
@ -428,18 +432,21 @@ interface(`selinux_set_all_booleans',`
gen_require(`
type security_t, secure_mode_policyload_t;
attribute boolean_type;
bool secure_mode_policyload;
bool secure_mode_policyload, secure_mode_setbool;
')
dev_search_sysfs($1)
allow $1 security_t:dir list_dir_perms;
allow $1 { boolean_type -secure_mode_policyload_t }:file rw_file_perms;
allow $1 boolean_type:file read_file_perms;
allow $1 secure_mode_policyload_t:file read_file_perms;
if (!secure_mode_setbool) {
allow $1 security_t:security setbool;
allow $1 { boolean_type -secure_mode_policyload_t }:file write_file_perms;
}
if(!secure_mode_policyload) {
if(!secure_mode_policyload && !secure_mode_setbool) {
allow $1 secure_mode_policyload_t:file write_file_perms;
}
')

View File

@ -7,13 +7,19 @@ policy_module(selinux, 1.18.0)
## <desc>
## <p>
## 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.
## Boolean to determine whether the system permits loading policy, and setting
## enforcing mode. Set this to true and you have to reboot to set it back.
## </p>
## </desc>
gen_bool(secure_mode_policyload,false)
## <desc>
## <p>
## Boolean to determine whether the system permits setting Booelan values.
## </p>
## </desc>
gen_bool(secure_mode_setbool,false)
attribute boolean_type;
attribute can_load_policy;
attribute can_setenforce;
@ -91,12 +97,22 @@ dev_search_sysfs(can_setsecparam)
allow selinux_unconfined_type security_t:dir list_dir_perms;
allow selinux_unconfined_type security_t:file rw_file_perms;
allow selinux_unconfined_type boolean_type:file read_file_perms;
allow selinux_unconfined_type { boolean_type -secure_mode_policyload_t }:file write_file_perms;
# Access the security API.
allow selinux_unconfined_type security_t:security { compute_av compute_create compute_member check_context compute_relabel compute_user setbool setsecparam setcheckreqprot read_policy validate_trans };
allow selinux_unconfined_type security_t:security { compute_av compute_create compute_member check_context compute_relabel compute_user setsecparam setcheckreqprot read_policy validate_trans };
if (!secure_mode_policyload) {
allow selinux_unconfined_type security_t:security { load_policy setenforce };
allow selinux_unconfined_type secure_mode_policyload_t:file write_file_perms;
}
if (!secure_mode_setbool) {
allow selinux_unconfined_type security_t:security setbool;
}
if (secure_mode_policyload && !secure_mode_setbool) {
allow selinux_unconfined_type { boolean_type -secure_mode_policyload_t }:file write_file_perms;
}
if (!secure_mode_policyload && !secure_mode_setbool) {
allow selinux_unconfined_type boolean_type:file write_file_perms;
}