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* bug#48872: Guix services: ‘chmod’ leaves opportunity to leak secrets
@ 2021-06-06 12:51 Xinglu Chen
  2021-06-08  8:55 ` Maxime Devos
  0 siblings, 1 reply; 3+ messages in thread
From: Xinglu Chen @ 2021-06-06 12:51 UTC (permalink / raw)
  To: 48872

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[  This was reported on the Nixpkgs bug tracker a few weeks ago
   <https://github.com/NixOS/nixpkgs/issues/121293>  ]

When doing something like

  (call-with-output-file FILE
    (lambda (port)
      (display SECRET port)))
  (chmod FILE #o400)

an unpriviliged user could open FILE before FILE had been chmod’ed, and
then read the contents of FILE.

One solution to this problem would be to use

  (mkdir (dirname FILE) #o400)

before writing SECRET to FILE.

I have identified at least two services which are vulnerable to this:

* ‘wireguard-service-type’ in (gnu services vpn)
* ‘patchwork-service-type’ in (gnu servicse web)



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^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2021-06-08 14:44 UTC | newest]

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2021-06-06 12:51 bug#48872: Guix services: ‘chmod’ leaves opportunity to leak secrets Xinglu Chen
2021-06-08  8:55 ` Maxime Devos
2021-06-08 14:42   ` Xinglu Chen

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