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    SubjectRe: [PATCH 3/7] SELinux: Stub in copy-up handling
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    On Friday, November 07, 2014 10:08:48 PM David Howells wrote:
    > Paul Moore <paul@paul-moore.com> wrote:
    > > > +static int selinux_inode_copy_up_xattr(struct dentry *src, struct
    > > > dentry
    > > > ...*dst,
    > > > + const char *name, void *value, size_t *size)
    > > > +{
    > > > + if (strcmp(name, XATTR_NAME_SELINUX) == 0)
    > > > + return 1; /* Discard */
    > >
    > > I understand that this is just a stub, but I we need to discuss this at
    > > some point and I figure better in this patch than elsewhere where it
    > > might get lost.
    > >
    > > For the docker, context= mount use case (similar to SELinux/sVirt)
    > > dropping
    > > the SELinux xattr is probably an okay behavior. However, I would expect
    > > that ultimately this is something we would want to control by policy
    > > and/or the presence of a context= label.
    >
    > The problem is that the label you actually want has already been set and you
    > have to be careful not to overwrite it.
    >
    > The other hook (->inode_copy_up) is called first to label the destination
    > inode - and that has access to the source file also so it can label the
    > destination with consideration of the attributes on the source. Normally,
    > the attributes on the source will be in memory attached to the source
    > inode, I would imagine.

    Hmmm, I guess I need to take a closer look at how overlayfs creates files
    during a copy on write.

    --
    paul moore
    www.paul-moore.com



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