Hi again,
Thanks again for all your help. I'm enjoying refactoring this, making
it better each time! I've learned a lot so far, and am starting to look
ready for tackling my next module, which will be for an in-house
application we use here at work.
I'm hoping to test this on a production server very soon. I'm also
chipping away at my colleagues whose only experience with selinux is to
turn it off! Some of them aren't too keen on the idea of me introducing
selinux on to our platform, but I'm just going to introduce it bit by
bit and make sure it's all documented well, and that they understand
what I'm up to.
# PowerDNS targeted enforcement module
policy_module(pdns,1.0.2)
type pdns_t;
type pdns_exec_t;
can_exec(pdns_t, pdns_exec_t)
init_daemon_domain(pdns_t, pdns_exec_t)
# /etc/pdns/pdns.conf
type pdns_conf_t;
files_config_file(pdns_conf_t)
read_files_pattern(pdns_t, pdns_conf_t, pdns_conf_t)
files_etc_filetrans(pdns_t, pdns_conf_t, file)
# /var/run/pdns.pid /var/run/pdns.controlsocket /var/run/subsys/pdns
type pdns_var_run_t;
files_pid_file(pdns_var_run_t)
manage_files_pattern(pdns_t, pdns_var_run_t, pdns_var_run_t)
manage_dirs_pattern(pdns_t, pdns_var_run_t, pdns_var_run_t)
manage_sock_files_pattern(pdns_t, pdns_var_run_t, pdns_var_run_t)
files_pid_filetrans(pdns_t, pdns_var_run_t, { dir file sock_file })
# General self privs
allow pdns_t self:capability { setuid chown fsetid kill setgid };
allow pdns_t self:fifo_file rw_fifo_file_perms;
allow pdns_t self:process signal_perms;
allow pdns_t self:tcp_socket create_stream_socket_perms;
allow pdns_t self:udp_socket create_socket_perms;
# General files access Macros
files_read_etc_files(pdns_t)
files_read_usr_files(pdns_t)
files_read_default_files(pdns_t)
libs_use_lib_files(pdns_t)
libs_use_ld_so(pdns_t)
miscfiles_read_localization(pdns_t)
# General Networky stuff
corenet_udp_bind_all_nodes(pdns_t)
corenet_tcp_bind_all_nodes(pdns_t)
# Syslog
logging_send_syslog_msg(pdns_t)
# Inbound DNS
corenet_udp_bind_dns_port(pdns_t)
corenet_udp_sendrecv_dns_port(pdns_t)
corenet_tcp_bind_dns_port(pdns_t)
corenet_tcp_sendrecv_dns_port(pdns_t)
# Inbound TCP 8081 for PDNS Web Server
corenet_tcp_bind_transproxy_port(pdns_t)
corenet_tcp_sendrecv_transproxy_port(pdns_t)
# Outbound DB Connectivity
corenet_tcp_connect_mysqld_port(pdns_t)
corenet_tcp_connect_mssql_port(pdns_t)
On 30/11/11 16:36, Daniel J Walsh wrote:
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On 11/30/2011 05:45 AM, Tom wrote:
Hi Again,
I've followed your advice, and I've removed all but one requirement
for var_run_t:sock_file. I couldn't find any interfaces which
would simply give me access to that, but it's certainly looking a
lot better, and a lot more readable! It could probably do with
some more re-factoring, but it's working well at the moment!
I haven't really thought too much about the file labelling. I've
only done the daemon binary, config file and /var/run/pdns.pid
file. I'm not sure I've followed best practices there at all.
Ok the next rule you need to follow, is if you need to write to a
"Generic" type, then you need to create your own type and potentially
transition to it.
# PowerDNS targeted enforcement module
policy_module(pdns,1.0.0)
require { type var_run_t; }
type pdns_t; type pdns_exec_t; allow pdns_t pdns_exec_t:file
execute_no_trans;
init_daemon_domain(pdns_t, pdns_exec_t)
# /etc/pdns/pdns.conf type pdns_conf_t;
files_config_file(pdns_conf_t)
# /var/run/pdns.pid type pdns_var_run_t;
files_pid_file(pdns_var_run_t)
# General self privs allow pdns_t self:capability { setuid chown
fsetid kill setgid }; allow pdns_t self:fifo_file { read getattr
ioctl };
allow pdns_t self:fifo_file rw_fifo_file_perms;
allow pdns_t self:process sigkill;
Might want to just add signal_perms;
allow pdns_t self:tcp_socket { setopt read bind create accept
write ioctl connect getopt listen };
allow pdns_t self:tcp_socket create_stream_socket_perms;
allow pdns_t self:udp_socket { read bind create write getattr };
allow pdns_t self:udp_socket create_socket_perms;
# Cannot figure out an interface to use with this one: allow pdns_t
var_run_t:sock_file { create setattr };
See below
# General files access Macros files_read_etc_files(pdns_t)
files_manage_usr_files(pdns_t)
You should have you own type? Whar file in /usr are you rewriting?
files_read_default_files(pdns_t) files_rw_generic_pids(pdns_t)
files_delete_all_pids(pdns_t)
Are you actually deleting other peoples content in /var/run? Or do
you have your own content in /var/run?
For example something like
manage_dirs_pattern(pdns_t, pdns_var_run_t, pdns_var_run_t)
manage_files_pattern(pdns_t, pdns_var_run_t, pdns_var_run_t)
manage_sock_files_pattern(pdns_t, pdns_var_run_t, pdns_var_run_t)
files_pid_filetrans(pdns_t, pdns_var_run_t, { dir file sock_file })
Then add a matching content in the fc file.
files_read_config_files(pdns_t) libs_use_lib_files(pdns_t)
libs_use_ld_so(pdns_t) miscfiles_read_localization(pdns_t)
# Core Network corenet_udp_bind_all_nodes(pdns_t)
corenet_tcp_bind_all_nodes(pdns_t)
# Syslog logging_send_syslog_msg(pdns_t)
# Inbound DNS corenet_udp_bind_dns_port(pdns_t)
corenet_udp_sendrecv_dns_port(pdns_t)
corenet_tcp_bind_dns_port(pdns_t)
corenet_tcp_sendrecv_dns_port(pdns_t)
# Inbound TCP 8081 for PDNS Web Server
corenet_tcp_bind_transproxy_port(pdns_t)
corenet_tcp_sendrecv_transproxy_port(pdns_t)
# Outbound DB Connectivity corenet_tcp_connect_mysqld_port(pdns_t)
corenet_tcp_connect_mssql_port(pdns_t)
Thanks again for your advice.
Tom.
On 29/11/11 16:27, Tom wrote:
Hi Daniel,
Thanks for this. I'm just about to leave work, but I'll be
looking again in the morning, and I'll get back to you and see
what you think of version 1.0.1! :)
Thanks again. Tom.
On 29/11/11 16:14, Daniel J Walsh wrote:
On 11/29/2011 10:56 AM, Tom wrote:
Greetings,
This is my first attempt at writing an selinux module.
I've basically done it by trying to confine the powerdns
service, and then worked through all of the problems I've
had in the audit log. At this point, my powerdns service
seems to work well with full functionality, however, I'm
sure there's about a million things I could be doing to
make it better. I'm still a bit shaky on the way I've done
the domain transition, and also, I'm sure there are a loads
of macros which I could be using, although I'm not sure
whether those types of things are distribution dependent.
I'm using CentOS 5.7, and have written this to fit in to
the targeted polifcy.
I'd be glad of any advice on how to do this type of thing
in a more efficient way.
Many thanks. Tom.
# cat pdns.te # PowerDNS targeted enforcement module
policy_module(pdns,1.0.0)
require { type etc_t; type lib_t; type usr_t; type
ld_so_cache_t; type ld_so_t; type lib_t; type locale_t;
type var_run_t; type devlog_t; type syslogd_t; type
initrc_var_run_t; type dns_port_t; type inaddr_any_node_t;
type transproxy_port_t; type mysqld_port_t; type
mssql_port_t; }
type pdns_t; type pdns_exec_t;
domain_type(pdns_t) domain_entry_file(pdns_t, pdns_exec_t)
init_daemon_domain(pdns_t, pdns_exec_t)
# /etc/pdns/pdns.conf type pdns_conf_t;
files_config_file(pdns_conf_t)
# /var/run/pdns.pid type pdns_var_run_t;
files_pid_file(pdns_var_run_t)
allow pdns_t etc_t:dir search; allow pdns_t etc_t:file {
getattr read }; allow pdns_t usr_t:dir search; allow pdns_t
usr_t:file { write create read getattr }; allow pdns_t
lib_t:dir { search getattr }; allow pdns_t lib_t:lnk_file
read; allow pdns_t lib_t:file { read getattr execute };
allow pdns_t ld_so_cache_t:file read; allow pdns_t
ld_so_cache_t:file getattr; allow pdns_t ld_so_t:file {
read execute }; allow pdns_t locale_t:file { read getattr
}; allow pdns_t pdns_conf_t:file read; allow pdns_t
var_run_t:dir { write remove_name add_name }; allow pdns_t
var_run_t:sock_file { unlink create setattr }; allow pdns_t
var_run_t:file { write create }; allow pdns_t
devlog_t:sock_file write; allow pdns_t
syslogd_t:unix_dgram_socket sendto; allow pdns_t
initrc_var_run_t:file write; allow pdns_t pdns_exec_t:file
execute_no_trans;
allow pdns_t self:process sigkill; allow pdns_t
self:fifo_file { getattr read ioctl write }; allow pdns_t
self:capability { chown fsetid net_bind_service setuid
setgid kill }; allow pdns_t self:unix_dgram_socket { create
connect write }; allow pdns_t self:udp_socket { create bind
read getattr write }; allow pdns_t self:tcp_socket { create
bind read getattr write setopt listen connect shutdown
accept getopt ioctl };
allow pdns_t inaddr_any_node_t:udp_socket node_bind; allow
pdns_t inaddr_any_node_t:tcp_socket node_bind;
# TCP + UDP Port 53 allow pdns_t dns_port_t:udp_socket
name_bind; allow pdns_t dns_port_t:tcp_socket name_bind;
# TCP 8081 for PDNS Web Server allow pdns_t
transproxy_port_t:tcp_socket name_bind;
# DB Connectivity allow pdns_t mysqld_port_t:tcp_socket
name_connect; allow pdns_t mssql_port_t:tcp_socket
name_connect;
# cat pdns.fc /usr/sbin/pdns_server --
gen_context(system_u:object_r:pdns_exec_t,s0)
/var/run/pdns.pid --
gen_context(system_u:object_r:pdns_var_run_t,s0)
/etc/pdns/pdns.conf --
gen_context(system_u:object_r:pdns_conf_t,s0)
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Tom try to remove the entire require block. You should be using
interfaces and not using the types directly in your policy.
All interfaces are available under
/usr/share/selinux/devel/include/...
For example.
allow pdns_t etc_t:dir search; allow pdns_t etc_t:file {
getattr read }; allow pdns_t usr_t:dir search; allow pdns_t
usr_t:file { write create read getattr };
Should be
files_read_etc_files(pdns_t) files_read_usr_files(pdns_t)
allow pdns_t transproxy_port_t:tcp_socket name_bind;
Should be
corenet_tcp_bind_transproxy_port(pdns_t)
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