• Pablo Neira Ayuso's avatar
    netlink: change return-value logic of netlink_broadcast() · ff491a73
    Pablo Neira Ayuso authored
    Currently, netlink_broadcast() reports errors to the caller if no
    messages at all were delivered:
    
    1) If, at least, one message has been delivered correctly, returns 0.
    2) Otherwise, if no messages at all were delivered due to skb_clone()
       failure, return -ENOBUFS.
    3) Otherwise, if there are no listeners, return -ESRCH.
    
    With this patch, the caller knows if the delivery of any of the
    messages to the listeners have failed:
    
    1) If it fails to deliver any message (for whatever reason), return
       -ENOBUFS.
    2) Otherwise, if all messages were delivered OK, returns 0.
    3) Otherwise, if no listeners, return -ESRCH.
    
    In the current ctnetlink code and in Netfilter in general, we can add
    reliable logging and connection tracking event delivery by dropping the
    packets whose events were not successfully delivered over Netlink. Of
    course, this option would be settable via /proc as this approach reduces
    performance (in terms of filtered connections per seconds by a stateful
    firewall) but providing reliable logging and event delivery (for
    conntrackd) in return.
    
    This patch also changes some clients of netlink_broadcast() that
    may report ENOBUFS errors via printk. This error handling is not
    of any help. Instead, the userspace daemons that are listening to
    those netlink messages should resync themselves with the kernel-side
    if they hit ENOBUFS.
    
    BTW, netlink_broadcast() clients include those that call
    cn_netlink_send(), nlmsg_multicast() and genlmsg_multicast() since they
    internally call netlink_broadcast() and return its error value.
    Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    ff491a73
dquot.c 67.4 KB