Re: Background fsck is broken

From: Poul-Henning Kamp (phk_at_phk.freebsd.dk)
Date: 12/15/04

  • Next message: Ted Lindgreen: "acpi is broken since about 2004/12/01" 
    To: Matthias Andree <ma@dt.e-technik.uni-dortmund.de>
Date: Wed, 15 Dec 2004 12:18:38 +0100

    In message <m33by7zula.fsf@merlin.emma.line.org>, Matthias Andree writes:
    >"Poul-Henning Kamp" <phk@phk.freebsd.dk> writes:
    >
    >> In message <20041215105326.GO25967@ip.net.ua>, Ruslan Ermilov writes:
    >>
    >>>Are you saying it's not possible to downgrade the open to
    >>>(r=1, w=0, e=0) when a file system is downgraded from R/W to R/O?
    >>
    >> Yes: that would make a read-only mounted filesystem vulnerable to
    >> overwriting through the /dev entry and we don't want that.
    >>
    >> The problem is that we do not in the kernel know if we are in single
    >> user mode or not.
    >
    >What difference does this make? Aren't secure levels or mandatory access
    >control and similar schemes sufficient to prevent tampering with direct
    >device access?

    No.

    >Why would not root be allowed to nuke a read-only mounted file system?
    >root has other means to trash a system, including writing junk into the
    >hardware registers.

    Just because root can go out of his way to do something stupid doesn't
    mean that we should make it easier to make an honest mistake.

    >On my wishlist, I've always wanted a "networked single user mode"
    >(i. e. only sshd running, only root login with key possible), and I've
    >always wondered why the whole system recovery is focused so much on the
    >principle of a "single-user console".

    Implement it! I've wanted that for a long time too. 

    -- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.
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  • Next message: Ted Lindgreen: "acpi is broken since about 2004/12/01"

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