On Tue, 2013-04-30 at 16:02 -0500, Robert Nichols wrote:

On 04/30/2013 12:39 PM, Robert Nichols wrote:

...

I have a script invoked from a procmail recipe that needs to perform actions involving searching for processes by name, playing sound through pulseaudio, sending mail, plus a few others. When I run with enforcing=0 I get 385 AVC denials (103KB, not attached), and that's _without_ disabling the "dontaudit" rules, which would yield over 100 more denials. The target contexts are not something I can change without totally destroying the current policy.

Any suggestions other than the 120 "allow" rules that audit2allow would suggest (and that's without considering the "dontaudit" denials)?

I'm getting _really_ tired of this. I'm spending more time trying to get things to work under SELinux than it would take me to recover from a (highly unlikely) intrusion. Sometimes the cost of insurance is just too high.

I tried setting up a domain transition, but it looks like a transition from procmail_t to unconfined_t just isn't going to be allowed. Since unconfined_t already has an entrypoint unconfined_exec_t, the module I installed is:

 module procmail_uncon 1.0;

 require {

type unconfined_t; type unconfined_exec_t; type procmail_t; class process { transition sigchld }; }

 allow procmail_t unconfined_t : process { transition sigchld };

Looks like you are missing an actual domain transition rule. There is also something fishy going on with role based access control.

Try this:

sudo semodule -r procmail_uncon

cat > mytest.te <<EOF policy_module(mytest, 1.0.0) optional_policy(` gen_require(` type procmail_t, unconfined_t, unconfined_exec_t; ') domtrans_pattern(procmail_t, unconfined_exec_t, unconfined_t) ') EOF

make -f /usr/share/selinux/devel/Makefile mytest.pp sudo semodule -i mytest.pp

Then try again, but keep a look out for any "SELINUX_ERR" messages in audit.log

There may be some RBAC related issues yet to resolve.

First things first: see where this gets you

That built and installed OK, and I gave the script the label unconfined_u:object_r:unconfined_exec_t:s0, but when procmail tries to execute it I get the error:

 type=SELINUX_ERR msg=audit(1367353892.747:26477): security_compute_sid: 

invalid context system_u:unconfined_r:procmail_t:s0 for scontext=system_u:system_r:procmail_t:s0 tcontext=unconfined_u:object_r:unconfined_exec_t:s0 tclass=process

and the desired transition does not occur.

Did I do something wrong there, or is disabling SELinux my only recourse?

On 05/01/2013 12:01 PM, Dominick Grift wrote:

On Tue, 2013-04-30 at 16:02 -0500, Robert Nichols wrote:

...

On 04/30/2013 12:39 PM, Robert Nichols wrote:

...

I have a script invoked from a procmail recipe that needs to perform actions involving searching for processes by name, playing sound through pulseaudio, sending mail, plus a few others. When I run with enforcing=0 I get 385 AVC denials (103KB, not attached), and that's _without_ disabling the "dontaudit" rules, which would yield over 100 more denials. The target contexts are not something I can change without totally destroying the current policy.

Any suggestions other than the 120 "allow" rules that audit2allow would suggest (and that's without considering the "dontaudit" denials)?

I'm getting _really_ tired of this. I'm spending more time trying to get things to work under SELinux than it would take me to recover from a (highly unlikely) intrusion. Sometimes the cost of insurance is just too high.

I tried setting up a domain transition, but it looks like a transition from procmail_t to unconfined_t just isn't going to be allowed. Since unconfined_t already has an entrypoint unconfined_exec_t, the module I installed is:

  module procmail_uncon 1.0;

  require {

type unconfined_t; type unconfined_exec_t; type procmail_t; class process { transition sigchld }; }

  allow procmail_t unconfined_t : process { transition sigchld };

Looks like you are missing an actual domain transition rule. There is also something fishy going on with role based access control.

Try this:

sudo semodule -r procmail_uncon

cat > mytest.te <<EOF policy_module(mytest, 1.0.0) optional_policy(` gen_require(` type procmail_t, unconfined_t, unconfined_exec_t; ') domtrans_pattern(procmail_t, unconfined_exec_t, unconfined_t) ') EOF

make -f /usr/share/selinux/devel/Makefile mytest.pp sudo semodule -i mytest.pp

Then try again, but keep a look out for any "SELINUX_ERR" messages in audit.log

There may be some RBAC related issues yet to resolve.

First things first: see where this gets you

...

That built and installed OK, and I gave the script the label unconfined_u:object_r:unconfined_exec_t:s0, but when procmail tries to execute it I get the error:

  type=SELINUX_ERR msg=audit(1367353892.747:26477): security_compute_sid:

invalid context system_u:unconfined_r:procmail_t:s0 for scontext=system_u:system_r:procmail_t:s0 tcontext=unconfined_u:object_r:unconfined_exec_t:s0 tclass=process

and the desired transition does not occur.

Did I do something wrong there, or is disabling SELinux my only recourse?

-- selinux mailing list selinux@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/selinux

I would go with a different way and create a new domain - procmail_unconfined_t and make this domain as unconfined domain.

# cat myprocmail.te

require{ type procmail_t; }

type procmail_unconfined_exec_t; application_executable_file(procmail_unconfined_exec_t)

optional_policy(` type procmail_unconfined_t; domain_type(procmail_unconfined_t)

domain_entry_file(procmail_unconfined_t, procmail_unconfined_exec_t) role system_r types procmail_unconfined_t;

domtrans_pattern(procmail_t, procmail_unconfined_exec_t, procmail_unconfined_t)

allow procmail_t procmail_unconfined_exec_t:dir search_dir_perms; allow procmail_t procmail_unconfined_exec_t:dir read_file_perms; allow procmail_t procmail_unconfined_exec_t:file ioctl;

init_domtrans_script(procmail_unconfined_t)

optional_policy(` unconfined_domain(procmail_unconfined_t) ') ')

# make -f /usr/share/selinux/devel/Makefile mytest.pp # sudo semodule -i mytest.pp # chcon -t procmail_unconfined_exec_t PATH_TO_YOU_SCRIPTS

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On 05/02/2013 05:53 PM, Robert Nichols wrote:

On 05/02/2013 12:58 AM, Miroslav Grepl wrote:

...

I would go with a different way and create a new domain - procmail_unconfined_t and make this domain as unconfined domain.

# cat myprocmail.te

require{ type procmail_t; }

type procmail_unconfined_exec_t; application_executable_file(procmail_unconfined_exec_t)

optional_policy(` type procmail_unconfined_t; domain_type(procmail_unconfined_t)

domain_entry_file(procmail_unconfined_t, procmail_unconfined_exec_t) role system_r types procmail_unconfined_t;

domtrans_pattern(procmail_t, procmail_unconfined_exec_t, procmail_unconfined_t)

allow procmail_t procmail_unconfined_exec_t:dir search_dir_perms; allow procmail_t procmail_unconfined_exec_t:dir read_file_perms; allow procmail_t procmail_unconfined_exec_t:file ioctl;

init_domtrans_script(procmail_unconfined_t)

optional_policy(` unconfined_domain(procmail_unconfined_t) ') ')

# make -f /usr/share/selinux/devel/Makefile mytest.pp # sudo semodule -i mytest.pp # chcon -t procmail_unconfined_exec_t PATH_TO_YOU_SCRIPTS

Thanks, I _think_ that's basically what I ended up doing. [copied from my previous post]:

policy_module(procmail_uncon, 1.0.18)

gen_require(` type unconfined_t; type unconfined_exec_t; type procmail_t; role system_r; ')

type my_uncon_exec_t; files_type(my_uncon_exec_t)

allow procmail_t unconfined_t : process { transition sigchld }; domain_auto_trans(procmail_t, my_uncon_exec_t, unconfined_t) role system_r types unconfined_t;

One difference between what Miroslav showed and you did, was that your new domain is now unconfined_t and might transition to another domain. Whereas his would not, also any confined domain that was allowed to communicate with unconfined_t would be able t communicate with your domain. They would not in Mirsoslav's case.

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On 05/07/2013 09:42 AM, Robert Nichols wrote:

On 05/06/2013 11:40 AM, Daniel J Walsh wrote:

...

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On 05/02/2013 05:53 PM, Robert Nichols wrote:

...

On 05/02/2013 12:58 AM, Miroslav Grepl wrote:

...

I would go with a different way and create a new domain - procmail_unconfined_t and make this domain as unconfined domain.

# cat myprocmail.te

require{ type procmail_t; }

type procmail_unconfined_exec_t; application_executable_file(procmail_unconfined_exec_t)

optional_policy(` type procmail_unconfined_t; domain_type(procmail_unconfined_t)

domain_entry_file(procmail_unconfined_t, procmail_unconfined_exec_t) role system_r types procmail_unconfined_t;

domtrans_pattern(procmail_t, procmail_unconfined_exec_t, procmail_unconfined_t)

allow procmail_t procmail_unconfined_exec_t:dir search_dir_perms; allow procmail_t procmail_unconfined_exec_t:dir read_file_perms; allow procmail_t procmail_unconfined_exec_t:file ioctl;

init_domtrans_script(procmail_unconfined_t)

optional_policy(` unconfined_domain(procmail_unconfined_t) ') ')

# make -f /usr/share/selinux/devel/Makefile mytest.pp # sudo semodule -i mytest.pp # chcon -t procmail_unconfined_exec_t PATH_TO_YOU_SCRIPTS

Thanks, I _think_ that's basically what I ended up doing. [copied from my previous post]:

policy_module(procmail_uncon, 1.0.18)

gen_require(` type unconfined_t; type unconfined_exec_t; type procmail_t; role system_r; ')

type my_uncon_exec_t; files_type(my_uncon_exec_t)

allow procmail_t unconfined_t : process { transition sigchld }; domain_auto_trans(procmail_t, my_uncon_exec_t, unconfined_t) role system_r types unconfined_t;

One difference between what Miroslav showed and you did, was that your new domain is now unconfined_t and might transition to another domain. Whereas his would not, also any confined domain that was allowed to communicate with unconfined_t would be able t communicate with your domain. They would not in Mirsoslav's case.

Then I'll definitely stick with what I've got since it makes everything work the same way it does when I invoke procmail from the command line. procmail transitions to procmail_t only when invoked from certain other confined domains, and that is a large part of what was making my life difficult in testing. Now, my script runs the same whether procmail was running in domain procmail_t or unconfined_t.

Ok, just wanted you to know the differences.