On Mon, 2018-07-02 at 14:30 +0800, Xin Long wrote:
> This patch implements the feature described in rfc1812#section-5.3.5.2
> and rfc2644. It allows the router to forward directed broadcast when
> sysctl bc_forwarding is enabled.
>
> Note that this feature could be done by iptables -j TEE, but it would
> cause some problems:
> - target TEE's gateway param has to be set with a specific address,
> and it's not flexible especially when the route wants forward all
> directed broadcasts.
> - this duplicates the directed broadcasts so this may cause side
> effects to applications.
>
> Besides, to keep consistent with other os router like BSD, it's also
> necessary to implement it in the route rx path.
>
> Note that route cache needs to be flushed when bc_forwarding is
> changed.
>
> Signed-off-by: Xin Long <lucien....@gmail.com>
> ---
> include/linux/inetdevice.h | 1 +
> include/uapi/linux/ip.h | 1 +
> include/uapi/linux/netconf.h | 1 +
> net/ipv4/devinet.c | 11 +++++++++++
> net/ipv4/route.c | 6 +++++-
> 5 files changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
> index 27650f1..c759d1c 100644
> --- a/include/linux/inetdevice.h
> +++ b/include/linux/inetdevice.h
> @@ -93,6 +93,7 @@ static inline void ipv4_devconf_setall(struct in_device
> *in_dev)
>
> #define IN_DEV_FORWARD(in_dev) IN_DEV_CONF_GET((in_dev),
> FORWARDING)
> #define IN_DEV_MFORWARD(in_dev) IN_DEV_ANDCONF((in_dev),
> MC_FORWARDING)
> +#define IN_DEV_BFORWARD(in_dev) IN_DEV_ANDCONF((in_dev),
> BC_FORWARDING)
> #define IN_DEV_RPFILTER(in_dev) IN_DEV_MAXCONF((in_dev),
> RP_FILTER)
> #define IN_DEV_SRC_VMARK(in_dev) IN_DEV_ORCONF((in_dev), SRC_VMARK)
> #define IN_DEV_SOURCE_ROUTE(in_dev) IN_DEV_ANDCONF((in_dev), \
> diff --git a/include/uapi/linux/ip.h b/include/uapi/linux/ip.h
> index b24a742..e42d13b 100644
> --- a/include/uapi/linux/ip.h
> +++ b/include/uapi/linux/ip.h
> @@ -168,6 +168,7 @@ enum
> IPV4_DEVCONF_IGNORE_ROUTES_WITH_LINKDOWN,
> IPV4_DEVCONF_DROP_UNICAST_IN_L2_MULTICAST,
> IPV4_DEVCONF_DROP_GRATUITOUS_ARP,
> + IPV4_DEVCONF_BC_FORWARDING,
> __IPV4_DEVCONF_MAX
> };
>
> diff --git a/include/uapi/linux/netconf.h b/include/uapi/linux/netconf.h
> index c84fcdf..fac4edd 100644
> --- a/include/uapi/linux/netconf.h
> +++ b/include/uapi/linux/netconf.h
> @@ -18,6 +18,7 @@ enum {
> NETCONFA_PROXY_NEIGH,
> NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN,
> NETCONFA_INPUT,
> + NETCONFA_BC_FORWARDING,
> __NETCONFA_MAX
> };
> #define NETCONFA_MAX (__NETCONFA_MAX - 1)
> diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
> index d7585ab..80cb464 100644
> --- a/net/ipv4/devinet.c
> +++ b/net/ipv4/devinet.c
> @@ -1827,6 +1827,8 @@ static int inet_netconf_msgsize_devconf(int type)
> size += nla_total_size(4);
> if (all || type == NETCONFA_MC_FORWARDING)
> size += nla_total_size(4);
> + if (all || type == NETCONFA_BC_FORWARDING)
> + size += nla_total_size(4);
> if (all || type == NETCONFA_PROXY_NEIGH)
> size += nla_total_size(4);
> if (all || type == NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN)
> @@ -1873,6 +1875,10 @@ static int inet_netconf_fill_devconf(struct sk_buff
> *skb, int ifindex,
> nla_put_s32(skb, NETCONFA_MC_FORWARDING,
> IPV4_DEVCONF(*devconf, MC_FORWARDING)) < 0)
> goto nla_put_failure;
> + if ((all || type == NETCONFA_BC_FORWARDING) &&
> + nla_put_s32(skb, NETCONFA_BC_FORWARDING,
> + IPV4_DEVCONF(*devconf, BC_FORWARDING)) < 0)
> + goto nla_put_failure;
> if ((all || type == NETCONFA_PROXY_NEIGH) &&
> nla_put_s32(skb, NETCONFA_PROXY_NEIGH,
> IPV4_DEVCONF(*devconf, PROXY_ARP)) < 0)
> @@ -2143,6 +2149,10 @@ static int devinet_conf_proc(struct ctl_table *ctl,
> int write,
> if ((new_value == 0) && (old_value != 0))
> rt_cache_flush(net);
>
> + if (i == IPV4_DEVCONF_BC_FORWARDING - 1 ||
> + new_value != old_value)
> + rt_cache_flush(net);
> +
> if (i == IPV4_DEVCONF_RP_FILTER - 1 &&
> new_value != old_value) {
> ifindex = devinet_conf_ifindex(net, cnf);
> @@ -2259,6 +2269,7 @@ static struct devinet_sysctl_table {
> DEVINET_SYSCTL_COMPLEX_ENTRY(FORWARDING, "forwarding",
> devinet_sysctl_forward),
> DEVINET_SYSCTL_RO_ENTRY(MC_FORWARDING, "mc_forwarding"),
> + DEVINET_SYSCTL_RW_ENTRY(BC_FORWARDING, "bc_forwarding"),
>
> DEVINET_SYSCTL_RW_ENTRY(ACCEPT_REDIRECTS, "accept_redirects"),
> DEVINET_SYSCTL_RW_ENTRY(SECURE_REDIRECTS, "secure_redirects"),
> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> index 1df6e97..b678466 100644
> --- a/net/ipv4/route.c
> +++ b/net/ipv4/route.c
> @@ -1996,8 +1996,11 @@ static int ip_route_input_slow(struct sk_buff *skb,
> __be32 daddr, __be32 saddr,
> goto no_route;
> }
>
> - if (res->type == RTN_BROADCAST)
> + if (res->type == RTN_BROADCAST) {
> + if (IN_DEV_BFORWARD(in_dev))
> + goto make_route;
> goto brd_input;
> + }
>
> if (res->type == RTN_LOCAL) {
> err = fib_validate_source(skb, saddr, daddr, tos,
> @@ -2014,6 +2017,7 @@ static int ip_route_input_slow(struct sk_buff *skb,
> __be32 daddr, __be32 saddr,
> if (res->type != RTN_UNICAST)
> goto martian_destination;
>
> +make_route:
> err = ip_mkroute_input(skb, res, in_dev, daddr, saddr, tos, flkeys);
> out: return err;
>
Acked-by: Davide Caratti <dcara...@redhat.com>
