Re: Samba hi_reserved_port_t denial

[Zdenek Pytela]

On Fri, Aug 14, 2020 at 9:40 AM <info(a)joomladev.eu&gt; wrote:

>  On CentOS 8 I have some weird permission denying on samba:
>
>  ------------------------------------------------------------------------------------
>  # audit(1597366122.204:23992513):
>  #  scontext="system_u:system_r:smbd_t:s0"
>  tcontext="system_u:object_r:hi_reserved_port_t:s0"
>  #  class="udp_socket" perms="name_bind"
>  #  comm="smbd" exe="" path=""
>  #  message="type=AVC msg=audit(1597366122.204:23992513): avc:  denied  {
>  #   name_bind } for  pid=2210721 comm="smbd" src=1009
>  #   scontext=system_u:system_r:smbd_t:s0
>  #   tcontext=system_u:object_r:hi_reserved_port_t:s0 tclass=udp_socket
>  #   permissive=1"
>
>  ------------------------------------------------------------------------------------
>  Do I something wrong?
>  
Hi Filip,

smbd is not allowed to bind to arbitrary udp ports, see:

# sesearch -A -s smbd_t -c udp_socket -p name_bind
allow nsswitch_domain ephemeral_port_t:udp_socket name_bind; [ nis_enabled
]:True
allow nsswitch_domain port_t:udp_socket name_bind; [ nis_enabled ]:True
allow nsswitch_domain unreserved_port_t:udp_socket name_bind; [ nis_enabled
]:True

So the question is: why smbd wants to bind to udp port 1009?


>  Thanks,
>  Filip Bartmann
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-- 

Zdenek Pytela
Security controls team, sst_platform_security