[PATCH net-next v2 06/10] net/ipv6: flip IPV6_SUBTREES default to Y
From: David 'equinox' Lamparter <hidden>
Date: 2026-07-23 12:23:58
Also in:
linux-doc, linux-kselftest
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
It's needed for RFC6724 rule 5.5, which as it turns out is more important than was initially discernible. Signed-off-by: David 'equinox' Lamparter <redacted> --- net/ipv6/Kconfig | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/net/ipv6/Kconfig b/net/ipv6/Kconfig
index c3806c6ac96f..39659e9b53a3 100644
--- a/net/ipv6/Kconfig
+++ b/net/ipv6/Kconfig@@ -243,16 +243,26 @@ config IPV6_MULTIPLE_TABLES config IPV6_SUBTREES bool "IPv6: source address based routing" depends on IPV6_MULTIPLE_TABLES + default y help Enable routing by source address or prefix. The destination address is still the primary routing key, so mixing normal and source prefix specific routes in the same routing table - may sometimes lead to unintended routing behavior. This can be - avoided by defining different routing tables for the normal and - source prefix specific routes. + may sometimes lead to unintended routing behavior if the order of + lookups is misunderstood. To achieve full separation based on source + address, different routing tables should be defined for each source + prefix. - If unsure, say N. + Subtrees specifically address scenarios where local connectivity + between source prefixes is shared and unrestricted, but some + destinations (e.g. the default route) have more fine-grained rules. + + This feature is required to correctly support RFC6724 rule 5.5 in + source address selection. Rule 5.5 is a necessity for good + multihoming, renumbering and source prefix liveliness checks. + + If unsure, say Y. config IPV6_MROUTE bool "IPv6: multicast routing"
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2.53.0