sysv_ipc.c broken in v1.30 (was Re: sysvshm appearse broken in -current)

[Andrey Chernov]

On Sat, Dec 16, 2006 at 12:11:05PM +0000, Robert Watson wrote:
> >                * Always permit the creator/owner to update the object
> >                * protections regardless of whether the object mode
> >                * permits it.
> >                */
> >               if (mode & IPC_M)
> >                       return (0);
> >
> >I.e. old code not even check for IPC_W or IPC_R in case of IPC_M presense.
> 
> Is this conclusion a supposition or the result of testing?  Could you test 
> and see if this is true?

It comes just from code reading. First check for owner and next check for 
IPC_M bit _only_ (no other bits!) then return (0) i.e. success.

> >Moreover, old code allows _anything_ for suser:

> The new code should also allow anything, as long as the bits passed into 
> ipcperm() as requested modes are valid.  There's certainly a bug here 

I mean anything for suser ignoring completely any modes passed.
I.e. no EACCES should happen for suser in _any_ mode combination.

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