Messages in this thread | | | Date | Mon, 22 Feb 1999 01:18:15 +0100 | From | ralf@uni-kobl ... | Subject | Re: fsync on large files |
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On Thu, Feb 18, 1999 at 03:11:04PM +0800, David Luyer wrote:
> It adds a whole new check to Linux security checkers, and a while new > incompatibility to mainstream Unix. > > Maybe I'm just paranoid. But every little change like this makes me worry. > (I'm still not happy that ld.so doesn't protect execute-only binaries from > LD_PRELOADs reading their code pages, and so on... you can't depend on Linux > enforcing traditional Unix security)
The possibility to hardlink directories is about as old as UNIX itself. I was actually not pleased at all when first used a ``modern'' UNIX after the end of my hard V7 times and found that this feature was gone. So if security scanners can't deal with it they missed more than just one decade of UNIX ...
The V7 solution for dealing with eventual problems was to make hardlinking directories a root-only operation, mainly to avoid funny things like
mknod("new-dir", S_IFDIR | 0755, 0); link("new-dir", "new-dir/..");
Anyway, afaik the reason why later Unices dropped hardlinked directories was that the semantics of ``..'' were very unobvious and got even more obscure when the original link was deleted, thus resulting in a single linked directory with a seemingly wrong parent.
Ralf
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