On Thu, 6 Oct 2005, David Howells wrote:
> James Morris <[email protected]> wrote:
>
> > I think this looks ok from an SELinux point of view if keys are treated as
> > opaque objects, i.e. like files.
>
> I'll make some changes based on the suggestions I've received. Those who
> request the return of keyfs can go boil their heads.
You know, I was thinking, ext3 could be much more compact if it was just a
set of custom syscalls and had no VFS representation.
What about a per process /proc/pid/keys, which contains keyrings and keys,
which can be opened, closed, use xattrs for any special access control
etc. ?
> > We could do something like create a new object class (kernkey or
> > something) and implement SELinux permissions for the class such as read,
> > write, search, link, setattr and getattr. Your KEY_VIEW perm could be
> > translated to SELinux getattr.
>
> Should I expand the permissions mask to include a setattr?
Possibly for setperm and chown.
> > I'm not sure if we need user-level labeling of keys via the set & get
> > security ops, although LSPP may require some form of get_security. If we
> > don't need to manually set security attributes but still view them, they
> > could be displayed via /proc/keys rather than implementing a separate
> > multiplexed syscall.
>
> Would it be worth me adding a key type op by which a security module can ask
> the type its opinion (or by which key_alloc() can ask the type to give the
> security module an earful)?
Well, SELinux is the only significant LSM in the tree and I don't think it
needs to set the labels. So, no.
> > keyctl_chown_key()
> > keyctl_setperm_key()
>
> Okay.
>
> > keyctl_set_reqkey_keyring()
>
> Should this really be securified? It merely controls the default destination
> for a key created by request_key(), and is limited to the keyrings the process
> is subscribed to in any case.
Ok, if needed, it can be added later.
> > All users of key_permission() need to propagate the error code from the
> > LSM back to the user.
>
> Really? Why?
Because the LSM has final say on the error code returned to the caller.
If the LSM runs out of memory, for example, it's silly to return -EACCES.
> Note that the fact that key_permission() fails for a key is sometimes ignored,
> such as when I'm doing a search and one potentially matching key fails, but a
> subsequent matching key passes.
Ok, that sounds like an internal issue to be resolved, ensuring that if
you are returning to the caller, the LSM's error code is returned.
- James
--
James Morris
<[email protected]>
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