target/linux/generic/backport-5.10/615-v5.14-ip-Treat-IPv4-segment-s-lowest-address-as-unicast.patch

   1 From 94c821c74bf5fe0c25e09df5334a16f98608db90 Mon Sep 17 00:00:00 2001
   2 From: Seth David Schoen <schoen@loyalty.org>
   3 Date: Wed, 12 May 2021 21:37:49 -0700
   4 Subject: [PATCH] ip: Treat IPv4 segment's lowest address as unicast
   5
   6 Treat only the highest, not the lowest, IPv4 address within a local
   7 subnet as a broadcast address.
   8
   9 Signed-off-by: Seth David Schoen <schoen@loyalty.org>
  10 Suggested-by: John Gilmore <gnu@toad.com>
  11 Acked-by: Dave Taht <dave.taht@gmail.com>
  12 Reviewed-by: David Ahern <dsahern@kernel.org>
  13 Signed-off-by: David S. Miller <davem@davemloft.net>
  14 Link: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=94c821c74bf5
  15 ---
  16  net/ipv4/fib_frontend.c | 4 +---
  17  1 file changed, 1 insertion(+), 3 deletions(-)
  18
  19 --- a/net/ipv4/fib_frontend.c
  20 +++ b/net/ipv4/fib_frontend.c
  21 @@ -1129,10 +1129,8 @@ void fib_add_ifaddr(struct in_ifaddr *if
  22                                   prefix, ifa->ifa_prefixlen, prim,
  23                                   ifa->ifa_rt_priority);
  24
  25 -               /* Add network specific broadcasts, when it takes a sense */
  26 +               /* Add the network broadcast address, when it makes sense */
  27                 if (ifa->ifa_prefixlen < 31) {
  28 -                       fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix, 32,
  29 -                                 prim, 0);
  30                         fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix | ~mask,
  31                                   32, prim, 0);
  32                         arp_invalidate(dev, prefix | ~mask, false);