Re: secilc: is anyone able to confirm that type_change ...

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On 07/09/2014 11:18 AM, Stephen Smalley wrote:
> On 07/09/2014 11:10 AM, Daniel J Walsh wrote:
>>
>> On 07/08/2014 03:35 PM, Stephen Smalley wrote:
>>> On 07/08/2014 03:21 PM, Steve Lawrence wrote:
>>>> On 07/07/2014 10:45 AM, Dominick Grift wrote:
>>>>> On Mon, 2014-07-07 at 16:24 +0200, Dominick Grift wrote:
>>>>>> On Mon, 2014-07-07 at 10:00 -0400, Steve Lawrence wrote:
>>>>>>
>>>>>>> I can't reproduce the problem with my test policies. The typechange
>>>>>>> statements look like they are correctly inserted into the binary and I
>>>>>>> am seeing the expected type changes at runtime.
>>>>>>>
>>>>>>> Is this with your monogam policy?
>>>>>>>
>>>>>> No, that one is no longer maintained.
>>>>>>
>>>>>> It is this very small base policy:
>>>>>>
>>>>>> https://github.com/doverride/e145
>>>>>>
>>>>> Note though, with that version, that there is no type_change rule from
>>>>> devpts_t to device_session_pts_t currently (so if you were to test this
>>>>> with sshd then it would be lacking the type change rule)
>>>>>
>>>>> Either insert that type_change rule manually or test it with the (local)
>>>>> login program since there is a type_change session_t
>>>>> device_tty_t:chr_file device_session_tty_t rule present.
>>>>>
>>>>> There is also a conditional type change rule for console_device_t to
>>>>> device_session_tty_t.
>>>>>
>>>>> I cannot imagine me having overlooked anything. Since there are only two
>>>>> domains (system_t and session_t), and both are virtually unconfined.
>>>>>
>>>>>
>>>> Ok, finally managed to track down this issue. Turns out to be an
>>>> ordering problem. You have your classes listed in alphabetical order.
>>>> Order shouldn't matter with CIL and everything should work correctly,
>>>> and in most cases is does. However, we assign integer values to each
>>>> class based on the order we see them. So the first one we see gets value
>>>> 1, second gets 2, etc. If these values don't match up with what
>>>> userspace and the kernel expect them to be, things break.
>>> Kernel and newer userspace code performs dynamic lookup of class/perm
>>> values from strings and handles mapping their own internal indices to
>>> the policy-defined values.  So this points to a need to update
>>> pam_selinux and other older code to map via string_to_security_class().
>> Lets open a bugzilla on this.
> 
> Probably need to crawl the fedora source tree and look for any #include
> <selinux/flask.h> or #include <selinux/av_permissions.h> references to
> identify all packages that need to be updated.

Or we could be evil and delete those two header files altogether, or be
a bit nicer and put #warning or #error in them.

I see we also wrongly use a hardcoded class in
libselinux/src/setexecfilecon.c; should fix that one too.

  For permission checks,
> can just switch over to using selinux_check_access() in most cases and
> then all the string lookups are handled for you as well as all of the
> ugliness of dealing with the AVC.  May want new wrapper functions for
> security_compute_* that take the class as a string and internally call
> string_to_security_class() that can be used instead.
> 
> 
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