Asterisk updates

Small patchset to support the "asterisk -r" command (asterisk CLI used often by administrators). Includes update on sysadm to become asterisk admin.

Wkr,
Sven Vermeulen

One of the most frequently ran commands by asterisk administrators is to run 'asterisk -r' to manipulate (through the asterisk socket) the asterisk daemon (sort-of asterisk-specific shell support).

We allow the asterisk administrator (through asterisk_admin) to execute the asterisk binary (no domtrans) and connect through the socket.

---
 asterisk.if |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

index 8b8143e..3164850 100644
@@ -62,6 +62,7 @@ interface(`asterisk_admin',`
 		type asterisk_etc_t, asterisk_tmp_t, asterisk_log_t;
 		type asterisk_var_lib_t;
 		type asterisk_initrc_exec_t;
+		type asterisk_exec_t;
 	')
 
 	allow $1 asterisk_t:process { ptrace signal_perms getattr };

@@ -89,4 +90,7 @@ interface(`asterisk_admin',`
 
 	files_list_pids($1)
 	admin_pattern($1, asterisk_var_run_t)
+
+	can_exec($1, asterisk_exec_t)
+	asterisk_stream_connect($1)
 ')

1.7.3.4

In theory looks good but i wonder if this will work in practice since you may have tested it with sysadm_t that is not a good representation of reality. These admin interfaces shouldnt be called by sysadm_t, they should instead be used with userdom_base_user_template.

like;

mkdir myasteriskadm; cd myasteriskadm;

echo "policy_module(myasteriskadm, 1.0.0)" userdom_base_user_template(myasteriskadm) role myasteriskadm_r; asterisk_admin(myasteriskadm_t, myasteriskadm_r) " > myasteriskadm.te;

and then for example:

echo "policy_module(mystaff, 1.0.0) gen_require(\` role staff_r, myasteriskadm_r; ') allow staff_r myasteriskadm_r;" > mystaff.te;

semanage user -m -L s0 -r s0-s0:c0.c1023 -R "staff_r system_r myasteriskadm_r sysadm_r" -P user staff_u

useradd -Z staff_u joe

sudo -t myasteriskadm_t -r myasteriskadm_r /etc/init.d/asterisk start

disclaimer: example have my have errors since i did it off the top of my mind.

I agree that role support here is important, but what is the rule when to add things to sysadm_t and when not? It also holds the apache_role...

Wkr,
Sven Vermeulen

*_admin() interfaces arent your average roles. (i guess thats why they dont call them *_admin_role())

sysadmin is already a general purpose admin. sysadm can already restart any service and edit almost any file so adding asterisk_admin() does add much functionality other than the "asterisk -r".

You can allow sysadm_t to run asterisk -r in other ways without including all the duplicate policy that you would by calling asterisk_admin for sysadm

So, yes roles() should be called in the role layer modules but asterisk_admin or any other _admin interface is not such a role. its different, its specific to confined root.

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Hmm, okay

[...]

Didn't know that, thanks.

I think it is best to mark the binary as an application_exec_type then as you suggested, and use the stream connect. I'll have it tested to see if that works.

Wkr,
Sven Vermeulen

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An asterisk admin should not be running the application in his his own context, he should be allowed to restart it in the asterisk_t domain which is why we have asterisk_initrc_exec_t. And are moving towards using asterisk_systemctl() for systemd controls.

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Having stream_connect rights doesn't allow him to run the application in his own domain. What this patch offers is to allow the asterisk admin to run "asterisk -r" so he can get the CLI open. The CLI doesn't work if asterisk isn't running, and restarting it doesn't refresh the process (so it remains running in asterisk_t), it is more of a reload.

The use of "asterisk -r" is often done by asterisk admins. We've asked a few of them to check if this is really necessary and they all agreed that having "asterisk -r" possible is a major requirement for asterisk administration.

The use of the init script is indeed still necessary for stop and start operations as well as some general management activities, but administering asterisk is more than just those operational activities.

Also, to reply to Dominick's suggestion to only have the asterisk_stream_connect for the asterisk admin, that won't work since he would still need can_exec rights on the asterisk_exec_t. Also, since he is asterisk admin, he'll need asterisk_admin() anyhow.

Wkr,
Sven Vermeulen

Yes sorry i overlooked that but still i think this may or may not be fixed better in a different way.

What i assumed was that sysadm_t was allowed to run any exec_type (that would include asterisk_exec_t) but i looked wrong.

sysadm_t can execute all application_exec_type instead and asterisk_exec_t is not that.

So either you also add the can_exec() to sysadms role policy module or you make asterisk_exec_t an application_executable_file or you allow sysadm-t to run all exec_types.

Which solution is best i am not sure, but i think i would prefer the application_executable_file(asterisk_exec_t)

Sure and i agree this should be supported but that should not be achieved by calling asterisk_admin for sysadm_t because many of the rules in there are duplicate for sysadm

sysadm is a general purpose admin role. So sysadm_t should be able to run asterisk -r (see above)

the asterisk_admin() is for administrators with more specific roles (not as broad as sysadm)

by having that interface we allow for the creation of these specific roles. (their just not installed by default)

sysadm should be able to manage all of asterisk and except for running asterisk -r i believe it can.

I did not say that allowing the can_exec() and stream_connect to asterisk_admin was a bad idea, i just said that i wonder if that is sufficient.

What i did say is that asterisk_admin() should not be called by sysadm-t because sysadm_t is already allowed to restart any system service and manage almost any file. So adding that would for the most part be adding duplicate rules (except for the support for asterisk -r which we should support, just not by calling asteriaks_admin for sysadm_t)

i am not saying that this policy should not be in asterisk_admin.

i am saying that sysadm_t should not call asterisk_admin()

instead allow sysadm to run asterisk_exec_t and allow sysadm to stream connect to asterisk.

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Give the asterisk administration role to the sysadm_r role.

---
 policy/modules/roles/sysadm.te |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

index 954417f..d9d6726 100644
@@ -86,6 +86,10 @@ optional_policy(`
 ')
 
 optional_policy(`
+	asterisk_admin(sysadm_t, sysadm_r)
+')
+
+optional_policy(`
 	auditadm_role_change(sysadm_r)
 ')
 

1.7.3.4