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Re: Hard link creation witout write access



On 2023-09-07 13:25, Taylor R Campbell wrote:
Today I learned that you can create hard links to a file you don't own
and can't write to or even read from:

$ su -l root -c 'touch /tmp/foo && chmod 600 /tmp/foo'
$ ln /tmp/foo /tmp/bar

This strikes me as bonkers and a likely source of security issues.

The possibly worst outcome of this is that someone removes /tmp/foo, and expect the file to be deleted, but it still stays around.

Other than that, this seems like a very expected behavior. It's just a second reference to a file. All the access control to the file is in the file. A reference to it is nothing that in itself carries much of anything else.

I mean, if you can see /tmp/foo, then I fail to see that having a /tmp/bar pointing to the same file is going to cause any issues.

or what am I missing?

  Johnny

--
Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt%softjar.se@localhost             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol


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