Re: problems with changing UID/GID

[Luca Barbieri]

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On Mon, 2002-08-26 at 19:16, Alan Cox wrote:
> On Mon, 2002-08-26 at 15:58, Thunder from the hill wrote:
> > I personally like the task->cred->cr_uid, etc. approach. Helps a lot.
> 
> It changes the whole semantics of every security test in Linux, and
> breaks most of them totally. Our syscalls know the uid is constant
> during the call
This is easily fixable by having a shared structure separate from the
private one and propagating modifications only when entering kernel
mode.
If we combine the syscall-trace and cred-propagation checks this can be
done without overhead in the common case (but needs care to avoid
races).

This is similar to what user space would do but faster and transparent.

(BTW, I don't plan to code this myself)

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