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Wed, 04 Feb 2026 14:53:15 -0800 (PST) From: Tom Herbert To: davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, justin.iurman@uliege.be, willemdebruijn.kernel@gmail.com, pabeni@redhat.com Cc: Tom Herbert , Justin Iurman Subject: [PATCH net-next v7 05/10] ipv6: Document defaults for max_{dst|hbh}_opts_number sysctls Date: Wed, 4 Feb 2026 14:51:49 -0800 Message-ID: <20260204225154.58245-6-tom@herbertland.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260204225154.58245-1-tom@herbertland.com> References: <20260204225154.58245-1-tom@herbertland.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Justin Iurman --- Documentation/networking/ip-sysctl.rst | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index 28c7e4f5ecf9..bafb2ab08d0e 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -2476,20 +2476,26 @@ mld_qrv - INTEGER Minimum: 1 (as specified by RFC6636 4.5) 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. + Maximum number of non-padding TLVs allowed in a Destination + 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