Re: [PATCH v7 4/9] seccomp: move no_new_privs into seccomp

On Tue, Jun 24, 2014 at 12:30 PM, Oleg Nesterov [off-list ref] wrote:

On 06/24, Andy Lutomirski wrote:

quoted

On Tue, Jun 24, 2014 at 12:18 PM, Oleg Nesterov [off-list ref] wrote:

quoted

quoted

-struct seccomp { };
+struct seccomp {
+     unsigned long flags;
+};

A bit messy ;)

I am wondering if we can simply do

        static inline bool current_no_new_privs(void)
        {
                if (current->no_new_privs)
                        return true;

        #ifdef CONFIG_SECCOMP
                if (test_thread_flag(TIF_SECCOMP))
                        return true;
        #endif

Nope -- privileged users can enable seccomp w/o nnp.

Indeed, I am stupid.

Still it would be nice to cleanup this somehow. The new member is only
used as a previous ->no_new_privs, just it is long to allow the concurent
set/get. Logically it doesn't even belong to seccomp{}.

We could add an unsigned long atomic flags field to task_struct.

Grr.  Why isn't there an unsigned *int* atomic bitmask type?  Even u64
would be better.  unsigned long is useless.

Oleg.

-- 
Andy Lutomirski
AMA Capital Management, LLC