netdev - [PATCH net-next v5 5/7] ipv6: Document defaults for max_{dst|hbh}_opts

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Message-ID: <20260126194826.236075-6-tom@herbertland.com>
Date: Mon, 26 Jan 2026 11:48:24 -0800
From: Tom Herbert <tom@...bertland.com>
To: davem@...emloft.net,
	kuba@...nel.org,
	netdev@...r.kernel.org,
	justin.iurman@...ege.be
Cc: Tom Herbert <tom@...bertland.com>
Subject: [PATCH net-next v5 5/7] ipv6: Document defaults for max_{dst|hbh}_opts_number sysctls

In the descriptions of max_dst_opts_number and max_hbh_opts_number
sysctls add text about how a zero setting means that a packet with
any Destination or Hop-by-Hop options is dropped.

Report the defaults for max_dst_opts_number and max_hbh_opts_number
are 2 which means up to two options may be accepted.

Signed-off-by: Tom Herbert <tom@...bertland.com>
---
 Documentation/networking/ip-sysctl.rst | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index bc9a01606daf..4f568b0e39d2 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -2475,19 +2475,25 @@ mld_qrv - INTEGER
 
 max_dst_opts_number - INTEGER
 	Maximum number of non-padding TLVs allowed in a Destination
-	options extension header. If this value is less than zero
-	then unknown options are disallowed and the number of known
-	TLVs allowed is the absolute value of this number.
+	options extension header. If this value is zero then receive
+	Destination Options processing is disabled in which case packets
+	with the Destination Options extension header are dropped. If
+	this value is less than zero then unknown options are disallowed
+	and the number of known TLVs allowed is the absolute value of
+	this number.
 
-	Default: 8
+        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 less than zero
-	then unknown options are disallowed and the number of known
-	TLVs allowed is the absolute value of this number.
-
-	Default: 8
+	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
+	and the number of known TLVs allowed is the absolute value of this
+	number.
+
+        Default: 2
 
 max_dst_opts_length - INTEGER
 	Maximum length allowed for a Destination options extension
-- 
2.43.0