lkml.org 
[lkml]   [2010]   [Aug]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH v3] netfilter: save the hash of the tuple in the original direction for latter use
    From
    Date
    Le vendredi 20 août 2010 à 22:53 +0800, Changli Gao a écrit :
    > Since we don't change the tuple in the original direction, we can save it
    > in ct->tuplehash[IP_CT_DIR_REPLY].hnode.pprev for __nf_conntrack_confirm()
    > use.
    >
    > __hash_conntrack() is split into two steps: ____hash_conntrack() is used
    > to get the raw hash, and __hash_bucket() is used to get the bucket id.
    >
    > In SYN-flood case, early_drop() doesn't need to recompute the hash again.
    >
    > Signed-off-by: Changli Gao <xiaosuo@gmail.com>
    > ---

    Hmm... so to accept a few more SYN packets per second in SYNFLOOD
    attack, we slow a bit normal operations ? (adding one test on each
    packet going through conntrack)

    If yes (I dont think we should, hackers are stronger than you anyway,
    just face it)

    v4:
    __read_mostly on nf_conntrack_rnd


    What would happen if we let the initialization of nf_conntrack_rnd
    only in the insertion case (like currently done) ?
    Only the first packet received on the machine/conntrack might be hashed
    on a wrong slot. Is it a big deal ? If yes, maybe find a way to
    recompute the hash in this case, instead of reusing 'wrong' one ?



    --
    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: 2010-08-20 17:13    [W:0.020 / U:31.176 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site