Re: Trying again: why am I getting denials in a directory that has been labeled..

[Gary Tierney]

On Wed, Jul 11, 2018 at 11:01:50AM -0400, mark wrote:
> Date: Sat, 30 Jun 2018 11:22:43 +0200
> From: Lukas Vrabec <lvrabec(a)redhat.com&gt;
> >
> > On 06/29/2018 10:15 PM, mark wrote:
> >
> >> As Lukas suggested, I tried to relabel the file. It didn't work, and
> >> the reason is this: we have the web under our own root directory, not
> >> under /var/www. We had done an semanage fcontext -e /var/www <ourpath>.
> >> When I tried to relcabel, it suggested I try to relabel using the
> > /var/www path,  which won't work. 
No, it's telling you that you need to add the file context specification 
under there, not relabel it.

> >>
> >> Is there any way around this?
> >> /<ourpath>/htdocs/<website>/cgi-bin/data/<the probelematic
> file>
> >
> > Could you attach complete outputs from semanage/ls (-Z)/ matchpathcon
> > commands? I would like to reproduce it to help you find issue.
>
> Sorry I couldn't get back to this sooner.
>
> semanage fcontext --modify -t httpd_sys_rw_content_t
> /<actual>/<path>/htdocs/<website>/cgi-bin/Counter/data/image.dat
> ValueError: File spec
> /<actual>/<path>/htdocs/<website>/cgi-bin/Counter/data/image.dat
> conflicts
> with equivalency rule '/<actual>/<path>/htdocs /var/www/html'; Try
> adding
> '/var/www/html/<website>/cgi-bin/Counter/data/image.dat' instead
>
> ll -Z:
> -rw-rw-r--. apache imagej unconfined_u:object_r:httpd_sys_script_exec_t:s0
> /<actual>/<path>/htdocs/<website>/cgi-bin/Counter/data/image.dat
>  
You can't add a file context specification under /<actual>/<path>/htdocs
because it is an alias/equivalent to /var/www/html.  Adding a rule 
specifically for /<actual>/<path>/htdocs would result in ambiguity.

Based on the equivalence rules, it follows that
/<actual>/<path>/htdocs/<website>/cgi-bin/Counter/data/image.dat is 
equivalent to /var/www/html/<website>/cg-bin/Counter/data/image.dat.

So if you wanted to create a file context specification for your aliased 
path, you need to create iit using the path of the alias' target.  E.g.,

$ semanage fcontext -a -t httpd_sys_rw_content_t 
'/var/www/html/[^/]+/cgi-bin/Counter/data/image.dat'

Now `matchpathcon /<actual>/<path>/htdocs/<website>/{..snip..}` should 
return a context with the correct type.

> matchpathcon:
> /<actual>/<path>/htdocs/<website>/cgi-bin/Counter/data/image.dat	system_u:object_r:httpd_sys_script_exec_t:s0
>
> Amd pf course there's no <website> under /var/www/html/
>  
No, and there doesn't have to be.  These semanage-fcontext inputs are 
just regexps to match pathnames, not paths to files on the filesystem.
To the SELinux labeling system, your files _are_ under 
/var/www/html/<website>.

>     mark
> _______________________________________________
> selinux mailing list -- selinux(a)lists.fedoraproject.org
> To unsubscribe send an email to selinux-leave(a)lists.fedoraproject.org
> Fedora Code of Conduct: https://getfedora.org/code-of-conduct.html
> List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines
> List Archives:
> https://lists.fedoraproject.org/archives/list/[e-mail]...