• David Gibson's avatar
    rtnetlink: Only supply IFLA_VF_PORTS information when RTEXT_FILTER_VF is set · c53864fd
    David Gibson authored
    Since 115c9b81 (rtnetlink: Fix problem with
    buffer allocation), RTM_NEWLINK messages only contain the IFLA_VFINFO_LIST
    attribute if they were solicited by a GETLINK message containing an
    IFLA_EXT_MASK attribute with the RTEXT_FILTER_VF flag.
    
    That was done because some user programs broke when they received more data
    than expected - because IFLA_VFINFO_LIST contains information for each VF
    it can become large if there are many VFs.
    
    However, the IFLA_VF_PORTS attribute, supplied for devices which implement
    ndo_get_vf_port (currently the 'enic' driver only), has the same problem.
    It supplies per-VF information and can therefore become large, but it is
    not currently conditional on the IFLA_EXT_MASK value.
    
    Worse, it interacts badly with the existing EXT_MASK handling.  When
    IFLA_EXT_MASK is not supplied, the buffer for netlink replies is fixed at
    NLMSG_GOODSIZE.  If the information for IFLA_VF_PORTS exceeds this, then
    rtnl_fill_ifinfo() returns -EMSGSIZE on the first message in a packet.
    netlink_dump() will misinterpret this as having finished the listing and
    omit data for this interface and all subsequent ones.  That can cause
    getifaddrs(3) to enter an infinite loop.
    
    This patch addresses the problem by only supplying IFLA_VF_PORTS when
    IFLA_EXT_MASK is supplied with the RTEXT_FILTER_VF flag set.
    Signed-off-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
    Reviewed-by: default avatarJiri Pirko <jiri@resnulli.us>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    c53864fd
rtnetlink.c 70.1 KB