Re: set permission/ownership for files generated by service

[Reza Alizadeh Majd <r.majd@pantherx.org>]

On Mon, 13 Jul 2020 22:01:47 -0400
Julien Lepiller <julien@lepiller.eu> wrote:

> Le 13 juillet 2020 20:18:09 GMT-04:00, Reza Alizadeh Majd
> <r.majd@pantherx.org> a écrit :
> >
> >my service definition is as follows:
> >
> >
> >--8<---------------cut here---------------start------------->8---
> >(define-record-type* <kyc-configuration>
> >  kyc-configuration make-kyc-configuration
> >  kyc-configuration?
> >  (package kyc-configuration-package
> >           (default kyc))
> >  (user kyc-configuration-user
> >        (default "kyc-service"))
> >  (group kyc-configuration-group
> >         (default "kyc-service")))
> >
> >(define %kyc-accounts
> >  (list (user-group (name "kyc-service"))
> >        (user-group (name "kyc-rpc"))
> >        (user-account
> >          (name "kyc-service")
> >          (group "kyc-service")
> >          (system? #f)
> >          (supplementary-groups '("wheel" "kyc-rpc" "video"))
> >          (comment "KYC service user"))))
> >
> >(define kyc-shepherd-service
> >  (match-lambda
> >    (($ <kyc-configuration> package user group)
> >      (list (shepherd-service
> >              (provision '(kyc))
> >              (documentation "Run KYC as a daemon.")
> >              (requirement '(networking user-processes))
> >              (modules `((srfi srfi-1)
> >                                (srfi srfi-26)
> >                                ,@%default-modules))
> >              (start #~(make-forkexec-constructor
> >                        (list
> >                           (string-append #$package "/bin/kyc"))
> >                        #:user #$user
> >                        #:group #$group
> >                        #:environment-variables
> >     (list  (string-append "PATH=" #$coreutils "/bin:" (getenv
> > "PATH")) (string-append "HOME=" "/home/" #$user))))
> >              (stop #~(make-kill-destructor)))))))
> >
> >(define kyc-service-type
> >  (service-type
> >    (name 'kyc)
> >    (extensions (list (service-extension shepherd-root-service-type
> >                                                  kyc-shepherd-service)
> >                             (service-extension account-service-type
> >                                               (const
> > %kyc-accounts)))) (default-value (kyc-configuration))))
> >
> >--8<---------------cut here---------------end--------------->8---
> >
> >is there anything that I missed for this service definition?   
> 
> I don't see in your snippet where you create the socket or where you
> change ownership of it, so I don't really understand what is going
> wrong.
> 
> Maybe the service itself is responsible for creating the socket and
> changing ownership? In that case, I wouldn't use #:uses or #:group,
> as these will run the service as the unpriviledged user from the
> start, instead of running it as root and letting it change user after
> it's set up things.
> 
> If you want to create the socket yourself, why not use an
> activation-service-type?

Thanks for your response, 

the application itself is responsible for creation of socket, and the
socket is created without problem, but when I try to change the
ownership for socket file, I receive "operation not permitted" error. 

I also logged in to the user responsible for running the service and
run the application manually, socket creation and permission set
operations were succeed. 

referring to above snippet, when I perform all these operations
manually, everything works without problem:

--8<---------------cut here---------------start------------->8---
kyc-service@kyc-station /tmp/rpc$ whoami 
kyc-service
kyc-service@kyc-station /tmp/rpc$ groups 
kyc-service wheel kyc-rpc
kyc-service@kyc-station /tmp/rpc$ ll
total 0
srwxr-xr-x 1 kyc-service kyc-service 0 Jul 14 04:22 kyc
kyc-service@kyc-station /tmp/rpc$ chown kyc-service:kyc-rpc kyc 
kyc-service@kyc-station /tmp/rpc$ ll
total 0
srwxr-xr-x 1 kyc-service kyc-rpc 0 Jul 14 04:22 kyc
--8<---------------cut here---------------end--------------->8---


-- 
Reza Alizadeh Majd
PantherX Team
https://www.pantherx.org/