lkml.org 
[lkml]   [2006]   [May]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 7/14] random: Remove SA_SAMPLE_RANDOM from network drivers
    On Fri, May 05, 2006 at 12:24:26PM -0500, Matt Mackall wrote:
    > I haven't seen such an analysis, scholarly or otherwise and my bias
    > here is to lean towards the paranoid.
    >
    > Assuming a machine with no TSC and an otherwise quiescent ethernet
    > (hackers burning the midnight oil), I think most of the
    > hard-to-analyze bits above get pretty transparent.

    As always, whether or not the packet arrival times could be guessable
    and/or controlled by an attacker really depends on your threat model.
    For someone who has an ethernet monitor attached directly to the
    segment right next to your computer, it's very likely that they would
    be successful in guessing the inputs into the entropy pool. However,
    an attacker with physical access to your machine could probably do all
    sorts of other things, such as install a keyboard sniffer, etc.

    For a remote attacker, life gets much more difficult. Each switch,
    router, and bridge effectively has a queue into which packets must
    flow through, and that is _not_ known to a remote attacker. This is
    especially true today, when most people don't even use repeaters, but
    rather switches/bridges, which effectly make each ethernet connection
    to each host its own separate collision domain (indeed that term
    doesn't even apply for modern high-speed ethernets).

    I've always thought the right answer is that whether or not network
    packet arrival times should be used as entropy input should be
    configurable, since depending on the environment, it might or might
    not be safe, and for some hosts (particularly diskless servers), the
    network might be the only source of entropy available to them.

    - Ted

    -
    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: 2006-05-05 21:15    [W:0.163 / U:1.612 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site