[PATCH net-next v10 05/10] ipv6: Document defaults for max_{dst|hbh}_opts_number sysctls

Tom Herbert
2026-05-04T18:52:58Z

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@herbertland.com>
Reviewed-by: Justin Iurman <justin.iurman@gmail.com>
---
Documentation/networking/ip-sysctl.rst | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 2e3a746fcc6d..453643c70c8d 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -2511,19 +2511,25 @@ 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.
+ 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: 8
+ Default: 2

max_dst_opts_length - INTEGER
Maximum length allowed for a Destination options extension
--
2.43.0