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68f983ba41
Backport patch from kernel 5.14. Treat only the highest, not the lowest, IPv4 address within a local subnet as a broadcast address, as subnets do not need two different broadcast addresses and networking documentation consistently prefers the highest address as broadcast. This patch was merged in upstream net-next tree in May 2021 at https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=94c821c74bf5 This eventually frees up one address per subnet. It matches behavior suggested in our Internet-Draft, and also the default behavior of OpenBSD and FreeBSD. Signed-off-by: Seth David Schoen <schoen@loyalty.org>
33 lines
1.3 KiB
Diff
33 lines
1.3 KiB
Diff
From 94c821c74bf5fe0c25e09df5334a16f98608db90 Mon Sep 17 00:00:00 2001
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From: Seth David Schoen <schoen@loyalty.org>
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Date: Wed, 12 May 2021 21:37:49 -0700
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Subject: [PATCH] ip: Treat IPv4 segment's lowest address as unicast
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Treat only the highest, not the lowest, IPv4 address within a local
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subnet as a broadcast address.
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Signed-off-by: Seth David Schoen <schoen@loyalty.org>
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Suggested-by: John Gilmore <gnu@toad.com>
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Acked-by: Dave Taht <dave.taht@gmail.com>
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Reviewed-by: David Ahern <dsahern@kernel.org>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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Link: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=94c821c74bf5
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---
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net/ipv4/fib_frontend.c | 4 +---
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1 file changed, 1 insertion(+), 3 deletions(-)
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--- a/net/ipv4/fib_frontend.c
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+++ b/net/ipv4/fib_frontend.c
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@@ -1129,10 +1129,8 @@ void fib_add_ifaddr(struct in_ifaddr *if
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prefix, ifa->ifa_prefixlen, prim,
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ifa->ifa_rt_priority);
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- /* Add network specific broadcasts, when it takes a sense */
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+ /* Add the network broadcast address, when it makes sense */
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if (ifa->ifa_prefixlen < 31) {
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- fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix, 32,
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- prim, 0);
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fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix | ~mask,
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32, prim, 0);
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arp_invalidate(dev, prefix | ~mask, false);
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