[yocto] Access Control List (ACL) permissions attributes not getting preserved in rootfs

[Kumar, Shrawan]

Thanks Joshua,

"postinst"  works!!  I could see the attributes set under "poky/build_qemux86/tmp/work/qemux86-poky-linux/core-image-minimal/1.0-r0/rootfs/".

 However, I still could not see the attributes after booting qemu. It seems during rootfs.ext4 (mkfs.ext4 command )creation when "create_image_ext4.sh" is called , again this is getting   lost.

Any idea on this ?


Regards
Shrawan





-----Original Message-----
From: Joshua G Lock [mailto:joshua.g.lock at linux.intel.com] 
Sent: Friday, August 12, 2016 7:22 PM
To: Kumar, Shrawan; yocto at yoctoproject.org
Subject: Re: [yocto] Access Control List (ACL) permissions attributes not getting preserved in rootfs

On Fri, 2016-08-12 at 12:33 +0000, Kumar, Shrawan wrote:
> Hello All,
>  
> I am  using  poky “ jethro”  , and  though  one of my recipe, I have 
> created user1 & user2 and then trying to set ACL rules  on 
> “helloworld” bin as below :
>  
>  
> do_install() {
>                     install -d ${D}${bindir}
>                     install -m 0700 helloworld ${D}${bindir}
>                     install -d ${D}/lib/systemd/system
>                     install -m 0700 hello.service 
> ${D}/lib/systemd/system/
>                     chown    user1:group1 ${D}${bindir}/helloworld
>                    setfacl -m u:user2:r-- ${D}${bindir}/helloworld }
>  
>  
> è When I see   on the devshell ( bitbake HelloWorld –c devshell)  :
> poky/build_qemux86/tmp/work/qemux86-poky-linux/core-image-
> minimal/1.0-r0/rootfs/usr/bin# getfacl helloworld    , I could see 
> that ACL permissions are set correctly as below :
> -        # file: helloworld
> -        # owner: user1
> -        # group: group1
> -        user::rwx
> -        user:user2:r--
> -        group::---
> -        mask::r--
> -        other::---
>  
> However, It does not seems to be getting preserved in rootfs. :
> /poky/build_qemux86/tmp/work/qemux86-poky-linux/core-image-
> minimal/1.0-r0/rootfs/usr/bin# getfacl helloworld # file: helloworld # 
> owner: user1 # group: group1 user::rwx
> group::---
> other::---
>  
> quick help  here would be highly appreciated

This is due to the fact that we don't currently have a mechanism to preserve xattr through to image construction[1].

The largest barrier for doig so is that the package managers (certainly dpkg and rpm) don't have any support for xattrs in packages (an image is populated via the package manager).

To the best of my knowledge the only option for adding some xattr/ACL is to use a postinst[2] to set the attributes after the package has been installed.

Regards,

Joshua

1. https://bugzilla.yoctoproject.org/show_bug.cgi?id=9858
2. http://www.yoctoproject.org/docs/2.1/dev-manual/dev-manual.html#new-
recipe-post-installation-scripts