Messages in this thread | | | From | Bodo Eggert <> | Subject | Re: O_NOLINK for open() | Date | Thu, 13 Sep 2007 00:33:26 +0200 |
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Brent Casavant <bcasavan@sgi.com> wrote:
[...] > I could mmap a temporary tmpfs file (tmpfs so that if there is a > machine crash no sensitive data persists) which is created with > permissions of 0, immediately unlink it, and pass the file > descriptor through an AF_UNIX socket. This does open up a very > small window of vulnerability if another process is able to chmod > the file and open it before the unlink.
If the process can chmod the file, it can ptrace the daemon, too. Or, using CAP_DAC_OVERRIDE, it can patch the daemon.
Both will void any security.
> However, it occurs to me that this problem goes away if there were > a method create a file in an unlinked state to begin with. However > there does not appear to be any such mechanism in Linux's open() > interface.
Having no window for creating stale temp files is nice to have. We only need a clever fool to implement it.-) But since it's hard to get killed just in the right moment for having a stale temp file, there is very low interest for this feature. -- You know you're in trouble when packet floods are competing to flood you. -- grc.com
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