Re: SELinux blocking Dovecot from mysqld socket

On 2/6/19 11:04 AM, Lukas Vrabec wrote:
> On 2/6/19 10:59 AM, Ondrej Mosnacek wrote:
>> On Tue, Feb 5, 2019 at 6:57 PM Robert Moskowitz <[email protected]> wrote:
>>> On 2/5/19 10:41 AM, Ondrej Mosnacek wrote:
>>>> On Tue, Feb 5, 2019 at 2:54 PM Robert Moskowitz <[email protected]> wrote:
>>>>>
>>>>> On 2/5/19 3:23 AM, Zdenek Pytela wrote:
>>>>>
>>>>>
>>>>>
>>>>> On Mon, Feb 4, 2019 at 9:03 PM Robert Moskowitz <[email protected]> wrote:
>>>>>> I am working with Centos7:
>>>>>>
>>>>>> I have configured Dovecot to connect to mysqld via socket:
>>>>>>
>>>>>> connect = host=/var/lib/mysql/mysql.sock dbname=postfix user=postfix
>>>>>> password=Postfix_Database_Password
>>>>>>
>>>>>> I test sending a message with
>>>>>>
>>>>>> sendmail -i [email protected] < README
>>>>>>
>>>>>> This fails with the following message in maillog
>>>>>>
>>>>>> Feb  4 11:28:48 klovia dovecot: dict(13122): Error:
>>>>>> mysql(/var/lib/mysql/mysql.sock): Connect failed to database (postfix):
>>>>>> Can't connect to local MySQL server through socket
>>>>>> '/var/lib/mysql/mysql.sock' (13) - waiting for 25 seconds before retry
>>>>>>
>>>>>> If I setenforce to 0, the connection works.  So it clearly is an SELinux
>>>>>> problem.  I worked on this almost 2 years ago on another system and found:
>>>>>>
>>>>>> http://zszsit.blogspot.com/2012/12/dovecot-mysql-selinux-issue-on-centos6.html
>>>>>>
>>>>>> But I was hoping that there were better tools now with Centos7.  I
>>>>>> checked for setsebool at:
>>>>>>
>>>>>> https://linux.die.net/man/8/mysqld_selinux
>>>>>>
>>>>>> and tried:
>>>>>>
>>>>>> setsebool -P allow_user_mysql_connect 1
>>>>>>
>>>>>> But the mail still does not go unless I setenforce to 0.
>>>>> Hi,
>>>>>
>>>>> this boolean allows a different permission - see the manual page:
>>>>>>> If you want to allow users to connect to mysql, you must turn on the allow_user_mysql_connect boolean.
>>>>>> Is there someway to get SELinux to allow dovecot (and postfix) to
>>>>>> connect to mysqld?
>>>>> While dovecot is allowed to connect to postgresql port, there is no similar permission for mysql:
>>>>>
>>>>> # sesearch -A -s dovecot_t -c tcp_socket -p name_connect | grep sql
>>>>> allow dovecot_t postgresql_port_t:tcp_socket name_connect;
>>>>>
>>>>> However, if this permission is the only one missing, you can simply add it with:
>>>>>
>>>>> # echo '(allow dovecot_t mysqld_port_t (tcp_socket (name_connect)))' > dovecot-mysql.cil
>>>>> # semodule -i dovecot-mysql.cil
>>>>> # sesearch -A -s dovecot_t -c tcp_socket -p name_connect | grep sql
>>>>> allow dovecot_t mysqld_port_t:tcp_socket name_connect;
>>>>> allow dovecot_t postgresql_port_t:tcp_socket name_connect;
>>>>>
>>>>>
>>>>> Still getting the error.  This does not seem to be what is needed.  Isn't this to open TCP access where I am using the unix socket interface?
>>>> Indeed, what Zdenek advised is for allowing to connect via TCP. Could
>>>> you try the following instead?
>>>>
>>>> dnf install selinux-policy-devel
>>> Nit this is CentOS7, so yum.  In fact it is CentOS7-armhfp...
>>>
>>>> cat >dovecot_mysql.te <<EOF
>>>> policy_module(dovecot_mysql,1.0.0)
>>>> gen_require(`
>>>>          type dovecot_t;
>>>> ')
>>>> mysql_read_config(dovecot_t)
>>>> mysql_stream_connect(dovecot_t)
>>>> EOF
>>> For some reason this made an empty file.  Don't know if it was the lack
>>> of spaces on that first line?  I use this myself a lot, but always put
>>> spaces around the > and <<
>> As other have already pointed out, it was because of the unescaped
>> backtick. I initially started with just the last two lines and later
>> realized the other lines are also needed, so I just vim'd the file and
>> copy-pasted the new contents into the e-mail without checking if it
>> still works :)
>>
>>> So I just used vi this time.  :)
>>>
>>>> make -f /usr/share/selinux/devel/Makefile dovecot_mysql.pp
>>>> semodule -i dovecot_mysql.pp
>>> And the sendmail test went through with enforcing.
>>>
>>> thanks!
>> Great! I submitted a PR to allow this in Fedora policy, since it seems
>> like a valid use case. Hopefully it gets to RHEL/CentOS from there
>> eventually.
>>
>> https://github.com/fedora-selinux/selinux-policy-contrib/pull/86
>>
> Thanks Ondrej, for PR, it's already merged and back ported to Fedora 28
> and Fedora 29.
>
> https://github.com/fedora-selinux/selinux-policy-contrib/commit/e7c5f327c12dac498cfef69f9a4f9a3d57fa8677
>
> Robert,
>
> Do you have some more SELinux denials (AVC msgs) in audit.log after
> workaround from Ondrej? If yes, please attach it , we can work on them.
>
looking at https://wiki.dovecot.org/AuthDatabase/SQL I suspect

mysql_tcp_connect(dovecot_t)

is also neede for someone not using a local db.


- Thomas


https://github.com/fedora-selinux/selinux-policy-contrib/blob/rawhide/mysql.if#L85
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