• Eric Dumazet's avatar
    inet: frags: break the 2GB limit for frags storage · 7f617068
    Eric Dumazet authored
    Some users are willing to provision huge amounts of memory to be able
    to perform reassembly reasonnably well under pressure.
    
    Current memory tracking is using one atomic_t and integers.
    
    Switch to atomic_long_t so that 64bit arches can use more than 2GB,
    without any cost for 32bit arches.
    
    Note that this patch avoids an overflow error, if high_thresh was set
    to ~2GB, since this test in inet_frag_alloc() was never true :
    
    if (... || frag_mem_limit(nf) > nf->high_thresh)
    
    Tested:
    
    $ echo 16000000000 >/proc/sys/net/ipv4/ipfrag_high_thresh
    
    <frag DDOS>
    
    $ grep FRAG /proc/net/sockstat
    FRAG: inuse 14705885 memory 16000002880
    
    $ nstat -n ; sleep 1 ; nstat | grep Reas
    IpReasmReqds                    3317150            0.0
    IpReasmFails                    3317112            0.0
    Signed-off-by: 's avatarEric Dumazet <edumazet@google.com>
    Signed-off-by: 's avatarDavid S. Miller <davem@davemloft.net>
    (cherry picked from commit 3e67f106f619dcfaf6f4e2039599bdb69848c714)
    Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    7f617068