• Cong Wang's avatar
    net: introduce a knob to control whether to inherit devconf config · 856c395c
    Cong Wang authored
    There have been many people complaining about the inconsistent
    behaviors of IPv4 and IPv6 devconf when creating new network
    namespaces.  Currently, for IPv4, we inherit all current settings
    from init_net, but for IPv6 we reset all setting to default.
    
    This patch introduces a new /proc file
    /proc/sys/net/core/devconf_inherit_init_net to control the
    behavior of whether to inhert sysctl current settings from init_net.
    This file itself is only available in init_net.
    
    As demonstrated below:
    
    Initial setup in init_net:
     # cat /proc/sys/net/ipv4/conf/all/rp_filter
     2
     # cat /proc/sys/net/ipv6/conf/all/accept_dad
     1
    
    Default value 0 (current behavior):
     # ip netns del test
     # ip netns add test
     # ip netns exec test cat /proc/sys/net/ipv4/conf/all/rp_filter
     2
     # ip netns exec test cat /proc/sys/net/ipv6/conf/all/accept_dad
     0
    
    Set to 1 (inherit from init_net):
     # echo 1 > /proc/sys/net/core/devconf_inherit_init_net
     # ip netns del test
     # ip netns add test
     # ip netns exec test cat /proc/sys/net/ipv4/conf/all/rp_filter
     2
     # ip netns exec test cat /proc/sys/net/ipv6/conf/all/accept_dad
     1
    
    Set to 2 (reset to default):
     # echo 2 > /proc/sys/net/core/devconf_inherit_init_net
     # ip netns del test
     # ip netns add test
     # ip netns exec test cat /proc/sys/net/ipv4/conf/all/rp_filter
     0
     # ip netns exec test cat /proc/sys/net/ipv6/conf/all/accept_dad
     0
    
    Set to a value out of range (invalid):
     # echo 3 > /proc/sys/net/core/devconf_inherit_init_net
     -bash: echo: write error: Invalid argument
     # echo -1 > /proc/sys/net/core/devconf_inherit_init_net
     -bash: echo: write error: Invalid argument
    Reported-by: default avatarZhu Yanjun <Yanjun.Zhu@windriver.com>
    Reported-by: default avatarTonghao Zhang <xiangxia.m.yue@gmail.com>
    Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com>
    Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
    Acked-by: default avatarNicolas Dichtel <nicolas.dichtel@6wind.com>
    Acked-by: default avatarTonghao Zhang <xiangxia.m.yue@gmail.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    856c395c
devinet.c 66.9 KB