Re: [PATCH] new syscall: flink

["H. Peter Anvin" <hpa@zytor.com>]

Followup to:  <b6scsk$18b$1@penguin.transmeta.com>
By author:    torvalds@transmeta.com (Linus Torvalds)
In newsgroup: linux.dev.kernel
> 
> As others have pointed out, there is no way in HELL we can do this
> securely without major other incursions.
> 

If so, we already have the security hole... and we need to fix it.

> In particular, both flink() and funlink() require that you do all the
> same permission checks that a real link() or unlink() would do. And as
> some of them are done on the _source_ of the file, that implies that
> they have to be done at open() time.

[f]link() doesn't do any checks that open() doesn't, except for the
O_RDONLY/O_WRONLY/O_RDWR flags.

	-hpa
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