Re: Relocating mysql

Hi Gionatan,

On Wed, May 17, 2023 at 10:10 PM Gionatan Danti <[email protected]> wrote:

> Hi all,
> I have a question about mysql relocation.
>
> I already created an equivalency rule such as "semanage fcontext --list
> -C" returns the following:
> SELinux Local fcontext Equivalence
> /mnt/lv_data/var/lib/mysql = /var/lib/mysql
>
This is correct.


>
> Then I created a symlink in /var/lib:
> system_u:object_r:mysqld_db_t:s0    26 May 17 14:39 mysql ->
> /mnt/lv_data/var/lib/mysql
>
> However, httpd/php can not connect to the database. The following
> message is logged in audit.log:
> type=AVC msg=audit(1684352064.936:232): avc:  denied  { read } for
> pid=8558 comm="httpd" name="mysql" dev="sda4" ino=147925
> scontext=system_u:system_r:httpd_t:s0
> tcontext=system_u:object_r:mysqld_db_t:s0 tclass=lnk_file permissive=0
>
> My understanding is that httpd can not read the symlink. I expected to
> find a boolean to allow this kind of access, to no avail.
>
httpd can only read and write mysql sockets, so far there was no need to
allow other interactions.


> So my question is: can I allow httpd symlink access without manually
> modifying the actual policy (ie: using audit2allow and the likes)?
>
You can change the value of datadir in mysql configuration.
Otherwise, as in all such changes, you need to create a local policy to
back that change. It can be as easy as

f38# cat local_mysqld_symlink.cil
(allow httpd_t mysqld_db_t (lnk_file (getattr read)))
f38# semodule -i local_mysqld_symlink.cil


>
> Thanks.
>
> --
> Danti Gionatan
> Supporto Tecnico
> Assyoma S.r.l. - www.assyoma.it
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-- 

Zdenek Pytela
Security SELinux team

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