lkml.org 
[lkml]   [2001]   [Nov]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: PROBLEM: Linux updates RTC secretly when clock synchronizes
    On Fri, Nov 09, 2001 at 10:54:10PM +0000, Riley Williams wrote:

    > Hi Pavel.
    >
    > >>>> According to your comments, you prefer (2).
    > >>>> I most definitely prefer (1).
    >
    > >>> Hmm, and if some malicious software insmods kernel module to
    > >>> work around your printk()?
    >
    > >> ...it gets "Port busy" when it tries to access the RTC ports that the
    > >> RTC driver built into the kernel already has opened exclusively. At
    > >> least, that's my understanding of the situation at present.
    >
    > > It does not work that way. Userland does iopl(0), and then it just
    > > bangs any port it wants to.
    >
    > If any user can do that, then Linux is borken solid.
    >
    > Just out of curiosity, what is wrong with the idea of having the kernel
    > at iopl(0), any kernel modules at either iopl(1) or iopl(2) and apps at
    > iopl(3) ??? There is obviously something, but I've no idea what.

    Kernel stuff (kernel, modules) run at iopl(0). Only root programs can request
    iopl(0) for itself, otherwise all hell would break loose (eg, user 'nobody'
    writing to the hdd etc...)

    --

    Mark Zealey
    mark@zealos.org
    mark@itsolve.co.uk

    UL++++>$ G!>(GCM/GCS/GS/GM) dpu? s:-@ a16! C++++>$ P++++>+++++$ L+++>+++++$
    !E---? W+++>$ N- !o? !w--- O? !M? !V? !PS !PE--@ PGP+? r++ !t---?@ !X---?
    !R- b+ !tv b+ DI+ D+? G+++ e>+++++ !h++* r!-- y--

    (www.geekcode.com)
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 13:13    [W:0.024 / U:0.240 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site