Modul kebijakan SELinux dibangun dengan langkah-langkah berikut:
- menghasilkan seperangkat aturan kebijakan:
audit2allow
- menyusun:
checkmodule
- membangun:
semodule_package
http://wiki.centos.org/HowTos/SELinux
Dengan asumsi bahwa saya memiliki postgreylocal.te
file dengan konten berikut:
module postgreylocal 1.0;
require {
type postfix_smtpd_t;
type postfix_spool_t;
type initrc_t;
class sock_file write;
class unix_stream_socket connectto;
}
#============= postfix_smtpd_t ==============
allow postfix_smtpd_t initrc_t:unix_stream_socket connectto;
allow postfix_smtpd_t postfix_spool_t:sock_file write;
postgreylocal.pp
modul kebijakan akan dibuat dengan:
# checkmodule -M -m -o postgreylocal.mod postgreylocal.te
# semodule_package -m postgreylocal.mod -o postgreylocal.pp
Untuk membongkar modul kebijakan ini, Anda memerlukan alat yang disebut semodule_unpackage untuk mengekstrak .mod
file dan kemudian gunakan dismod
untuk membongkar modul biner ke representasi tekstual.
Di Gentoo saya, paket-paket berikut perlu diinstal:
[I] sys-apps/policycoreutils
Available versions: [M]2.0.82 [M](~)2.0.82-r1 [M](~)2.0.85 [M](~)2.1.0 {M}(~)2.1.0-r1
Installed versions: 2.1.0-r1(05:12:27 PM 10/14/2011)
Homepage: http://userspace.selinuxproject.org
Description: SELinux core utilities
[I] sys-apps/checkpolicy
Available versions: [M]2.0.21 [M](~)2.0.23 {M}(~)2.1.0 {debug}
Installed versions: 2.1.0(01:27:53 PM 10/14/2011)(-debug)
Homepage: http://userspace.selinuxproject.org
Description: SELinux policy compiler
[I] sys-libs/libsepol
Available versions: [M]2.0.41!t [M](~)2.0.42!t {M}(~)2.1.0!t
Installed versions: 2.1.0!t(01:25:43 PM 10/14/2011)
Homepage: http://userspace.selinuxproject.org
Description: SELinux binary policy representation library
Pertama, ekstrak modul dari .pp
file:
# semodule_unpackage postgreylocal.pp postgreylocal.mod
dan kedua, bongkar dengan dismod
:
# cd checkpolicy-2.1.0/test/
# ls
dismod.c dispol.c Makefile
# make
cc -g -Wall -O2 -pipe -I/usr/include -c -o dispol.o dispol.c
dispol.c: In function ‘main’:
dispol.c:438:8: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result
dispol.c:465:9: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result
dispol.c:476:9: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result
dispol.c:500:9: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result
cc dispol.o -lfl -lsepol -lselinux /usr/lib/libsepol.a -L/usr/lib -o dispol
cc -g -Wall -O2 -pipe -I/usr/include -c -o dismod.o dismod.c
dismod.c: In function ‘main’:
dismod.c:913:8: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result
dismod.c:982:9: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result
dismod.c: In function ‘link_module’:
dismod.c:787:7: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result
cc dismod.o -lfl -lsepol -lselinux /usr/lib/libsepol.a -L/usr/lib -o dismod
# ls
dismod dismod.c dismod.o dispol dispol.c dispol.o Makefile
./dismod postgreylocal.pp
Reading policy...
libsepol.policydb_index_others: security: 0 users, 1 roles, 3 types, 0 bools
libsepol.policydb_index_others: security: 0 sens, 0 cats
libsepol.policydb_index_others: security: 2 classes, 0 rules, 0 cond rules
libsepol.policydb_index_others: security: 0 users, 1 roles, 3 types, 0 bools
libsepol.policydb_index_others: security: 0 sens, 0 cats
libsepol.policydb_index_others: security: 2 classes, 0 rules, 0 cond rules
Binary policy module file loaded.
Module name: postgreylocal
Module version: 1.0
Select a command:
1) display unconditional AVTAB
2) display conditional AVTAB
3) display users
4) display bools
5) display roles
6) display types, attributes, and aliases
7) display role transitions
8) display role allows
9) Display policycon
0) Display initial SIDs
a) Display avrule requirements
b) Display avrule declarations
c) Display policy capabilities
l) Link in a module
u) Display the unknown handling setting
F) Display filename_trans rules
f) set output file
m) display menu
q) quit
Command ('m' for menu): 1
unconditional avtab:
--- begin avrule block ---
decl 1:
allow [postfix_smtpd_t] [initrc_t] : [unix_stream_socket] { connectto };
allow [postfix_smtpd_t] [postfix_spool_t] : [sock_file] { write };
Command ('m' for menu): a
avrule block requirements:
--- begin avrule block ---
decl 1:
commons: <empty>
classes: sock_file{ write } unix_stream_socket{ connectto }
roles : <empty>
types : postfix_smtpd_t postfix_spool_t initrc_t
users : <empty>
bools : <empty>
levels : <empty>
cats : <empty>
Command ('m' for menu):
sedismod
. Ini sudah tersedia bersama dengancheckpolicy
dansemodule_unpack
dengan instalasi default. Btw, viasemodule_unpackage foo.pp foo.mod foo.fc
Anda juga bisa mengekstrak file filecontexts.