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From: Tom Herbert <tom@herbertland.com>
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 <tom@herbertland.com>,
	Justin Iurman <justin.iurman@gmail.com>
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	[thread overview]
Message-ID: <20260204225154.58245-6-tom@herbertland.com> (raw)
In-Reply-To: <20260204225154.58245-1-tom@herbertland.com>

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 | 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


  parent reply	other threads:[~2026-02-04 22:53 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-04 22:51 [PATCH net-next v7 00/10] ipv6: Address ext hdr DoS vulnerabilities Tom Herbert
2026-02-04 22:51 ` [PATCH net-next v7 01/10] ipv6: Check of max HBH or DestOp sysctl is zero and drop if it is Tom Herbert
2026-02-04 22:51 ` [PATCH net-next v7 02/10] ipv6: Cleanup IPv6 TLV definitions Tom Herbert
2026-02-04 22:51 ` [PATCH net-next v7 03/10] ipv6: Add case for IPV6_TLV_TNL_ENCAP_LIMIT in EH TLV switch Tom Herbert
2026-02-04 22:51 ` [PATCH net-next v7 04/10] ipv6: Set HBH and DestOpt limits to 2 Tom Herbert
2026-02-04 22:51 ` Tom Herbert [this message]
2026-02-04 22:51 ` [PATCH net-next v7 06/10] ipv6: Enforce Extension Header ordering Tom Herbert
2026-02-04 22:51 ` [PATCH net-next v7 07/10] ipv6: Document enforce_ext_hdr_order sysctl Tom Herbert
2026-02-04 22:51 ` [PATCH net-next v7 08/10] test: Add proto_nums.py in networking selftests Tom Herbert
2026-02-04 22:51 ` [PATCH net-next v7 09/10] test: Add ext_hdr.py " Tom Herbert
2026-02-06  2:45 ` [PATCH net-next v7 00/10] ipv6: Address ext hdr DoS vulnerabilities Jakub Kicinski
     [not found]   ` <CALx6S3576DLyd18BnFRkaNMhxb-Y3bsy8YJXy3-Q43EQVppEDQ@mail.gmail.com>
2026-02-11 19:16     ` Jakub Kicinski

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