Re: [1/1][PATCH] nproc v2: netlink access to /proc information

[Chris Wright <chrisw@osdl.org>]

* Stephen Smalley (sds@epoch.ncsc.mil) wrote:
> Well, it isn't that easy, or at least I don't think it is.  The problem
> is that there is no way presently to convey the sender's security
> credentials (beyond the existing uid, cap information), since the LSM
> patches for adding security fields and hooks for managing skb security
> fields were rejected.  The best we can do at present is pass along the
> sender pid, uid, and cap, and the security module can look up the pid if
> it chooses to get the security field (but is naturally subject to races
> in that situation).
> 
> Most obvious place to hook would be nproc_ps_get_task; we could then
> perform a check based on the sender's credentials and the target task's
> credentials, and simply return NULL if permission is not granted for
> that pair, thus skipping that task as if it didn't exist.  That requires
> propagating the sender's credentials down to that function.
> 
> Untested patch below.
> 
> Index: linux-2.6/include/linux/security.h
> ===================================================================
> RCS file: /nfshome/pal/CVS/linux-2.6/include/linux/security.h,v
> retrieving revision 1.37
> diff -u -p -r1.37 security.h
> --- linux-2.6/include/linux/security.h	16 Jun 2004 14:49:42 -0000	1.37
> +++ linux-2.6/include/linux/security.h	9 Sep 2004 19:38:23 -0000
> @@ -632,6 +632,13 @@ struct swap_info_struct;
>   * 	security attributes, e.g. for /proc/pid inodes.
>   *	@p contains the task_struct for the task.
>   *	@inode contains the inode structure for the inode.
> + * @task_getstate:
> + * 	Check permission before getting the state of a task.
> + *      @pid contains the pid of the requesting process.
> + *	@p contains the task_struct for the target task.
> + *      @uid contains the uid of the requesting process.
> + *      @caps contains the capability set of the requesting process.
> + *      Return 0 if permission is granted.

Why caps?


thanks,
-chris
-- 
Linux Security Modules     http://lsm.immunix.org     http://lsm.bkbits.net