[lkml]   [2011]   [Jul]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [PATCH v2] kernel: escape non-ASCII and control characters in printk()
    > That said, if we really want to do this, I think doing it with %s
    > filtering is the only way, and it would make the default case where
    > people really don't think about possible user-supplied strings be
    > safe.
    > So saying "%s is for pure 7-bit ASCII with no control codes" is
    > annoying, but would really fix it.

    It's fairly easy for the console in question to provide a filter but 7bit
    ascii wouldn't be a bad default for a printing console, definitely a
    wrong default for the log file though.

    > That said, I think it should be unconditional. None of this "safe vs
    > unsafe" flags, and none of this "printk format strings are different
    > from other vsprintf format strings". If special characters are a
    > potential security problem for printk(), then they are a potential
    > security problem for other things (eg /proc filenames or content etc).

    In which case we can't do it because we need \n in proc content so that's
    a complete and utter non starter. In addition we have things with
    filenames in it and filenames are unicode so we'd break apps that look
    filenames up via /proc for things like monitoring.

    It depends how much you care as well - any idiot can figure out how to
    simply use spaces and/or tabs to build multiple lines of fake looking
    output like say a spoofed Oops.

    As Lars can no doubt remind people spoofing oopses can be fun ;)


     \ /
      Last update: 2011-07-03 23:11    [W:0.019 / U:4.420 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site