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    netlink: allow large data transfers from user-space · c05cdb1b
    Pablo Neira Ayuso 提交于
    I can hit ENOBUFS in the sendmsg() path with a large batch that is
    composed of many netlink messages. Here that limit is 8 MBytes of
    skbuff data area as kmalloc does not manage to get more than that.
    
    While discussing atomic rule-set for nftables with Patrick McHardy,
    we decided to put all rule-set updates that need to be applied
    atomically in one single batch to simplify the existing approach.
    However, as explained above, the existing netlink code limits us
    to a maximum of ~20000 rules that fit in one single batch without
    hitting ENOBUFS. iptables does not have such limitation as it is
    using vmalloc.
    
    This patch adds netlink_alloc_large_skb() which is only used in
    the netlink_sendmsg() path. It uses alloc_skb if the memory
    requested is <= one memory page, that should be the common case
    for most subsystems, else vmalloc for higher memory allocations.
    Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>
    Signed-off-by: NDavid S. Miller <davem@davemloft.net>
    c05cdb1b
af_netlink.c 67.6 KB