[PATCH net-next v7 07/10] ipv6: Document enforce_ext_hdr_order sysctl
From: Tom Herbert <hidden>
Date: 2026-02-04 22:53:21
Subsystem:
documentation, networking [general], the rest · Maintainers:
Jonathan Corbet, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Document the enforce_ext_hdr_order sysctl that controls whether Extension Header order is enforced on receive. Signed-off-by: Tom Herbert <redacted> --- Documentation/networking/ip-sysctl.rst | 34 ++++++++++++++++++++++++-- 1 file changed, 32 insertions(+), 2 deletions(-)
diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index bafb2ab08d0e..ce783551b687 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst@@ -2487,8 +2487,8 @@ max_dst_opts_number - INTEGER Default: 2 max_hbh_opts_number - INTEGER - Maximum number of non-padding TLVs allowed in a Hop-by-Hop - options extension header. If this value is zero then receive + Maximum number of non-padding TLVs allowed in a Hop-by-Hop + options extension header. If this value is zero then receive Hop-by-Hop Options processing is disabled in which case packets with the Hop-by-Hop Options extension header are dropped. If this value is less than zero then unknown options are disallowed
@@ -2583,6 +2583,36 @@ ioam6_id_wide - LONG INTEGER Default: 0xFFFFFFFFFFFFFF +enforce_ext_hdr_order - BOOLEAN + Enforce recommended Extension Header ordering in RFC8200. + If the sysctl is set to 1 then the ordering is enforced in + received packets and each Extension Header may be present + at most once per packet (except for Destination Options that + may occur twice). If the sysctl is set to 0 then ordering is + not enforced and Extension Headers may be present in any + order and have any number of occurrences per packet (except + for Hop-by-Hop Options that must always be the first Extension + Header and occur at most once in a packet)). + + The Extension Header order is: + + IPv6 header + Hop-by-Hop Options header + Destination Options before the Routing header + Routing header + Fragment header + Authentication header + Encapsulating Security Payload header + Destination Options header + Upper-Layer header + + Possible values: + + - 0 (disabled) + - 1 (enabled) + + Default: 1 (enabled) + IPv6 Fragmentation: ip6frag_high_thresh - INTEGER
--
2.43.0