Messages in this thread | | | Date | Wed, 31 Aug 2005 15:53:18 +0800 | From | Qi Yong <> | Subject | Re: syscall: sys_promote |
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Ulrich Drepper wrote:
>On 8/29/05, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote: > > >>Fixing it might be useful in some obscure cases anyway - POSIX threads >>might benefit from it too, providing the functionality of changing all >>thread uids at once isnt triggered for sensible threaded app behaviour. >> >> > >I would very much like to see that fixed. Currently we have to change >the UIDs/GIDs at userlevel with cross-thread calls implemented via >signals. This is user observable which is not correct. This is >probably the last area where we're not 100% POSIX compliant. > >As for adding this proposed syscall: it can only lead to chaos. All >kinds of user code correctly so assumes the IDs don't change over the >lifetime of a process. The solution for the problem has been > > After a user shell is promoted to root, its prompt is still $ instead of #. But why do we care?
>mentioned as well: re-exec. This will require some code rewrite on >the side of the applications but any decent daemon is hopefully soon > >
OK, so any decent processes should not break into other processes' address space. And let us use non-preemptive multitasking?
>support re-exec anyway for another reason: re-randomization of the >address space. What good does address space randomization do if the >machines and programs are so damn stable that they keep running for >months at a time? nscd supports this now and I think openssh as well. > >
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