[Virtio-fs] [PATCH 1/1] xattr: Allow user.* xattr on symlink/special files with CAP_SYS_RESOURCE
Christian Brauner
christian.brauner at ubuntu.com
Mon Jun 28 12:33:33 UTC 2021
On Fri, Jun 25, 2021 at 03:12:29PM -0400, Vivek Goyal wrote:
> As of now user.* xattrs are allowed only on regular files and directories.
> And in case of directories if sticky bit is set, then it is allowed
> only if caller is owner or has CAP_FOWNER.
>
> "man xattr" suggests that primary reason behind this restrcition is that
> users can set unlimited amount of "user.*" xattrs on symlinks and special
> files and bypass quota checks. Following is from man page.
>
> "These differences would allow users to consume filesystem resources in
> a way not controllable by disk quotas for group or world writable spe‐
> cial files and directories"
>
> Capability CAP_SYS_RESOURCE allows for overriding disk quota limits. If
> being able to bypass quota is primary reason behind these restrictions,
> can we relax these restrictions if caller has CAP_SYS_RESOURCE.
>
> Signed-off-by: Vivek Goyal <vgoyal at redhat.com>
> ---
I think this change is fine especially since it seems to solve a real
problem there since it prevents relabeling for virtiofsd.
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