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([2a02:a03f:a75e:9a00:7800:6d36:b552:d917]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-435e1322eefsm330917f8f.30.2026.01.27.09.50.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 27 Jan 2026 09:50:27 -0800 (PST) Message-ID: <6ad428fe-bdfb-41a6-baaf-786663e2223d@gmail.com> Date: Tue, 27 Jan 2026 18:50:26 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v5 1/7] ipv6: Check of max HBH or DestOp sysctl is zero and drop if it is To: Tom Herbert , davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org References: <20260126194826.236075-1-tom@herbertland.com> <20260126194826.236075-2-tom@herbertland.com> Content-Language: en-US From: Justin Iurman In-Reply-To: <20260126194826.236075-2-tom@herbertland.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/26/26 20:48, Tom Herbert wrote: > In IPv6 Destination options processing function check if > net->ipv6.sysctl.max_dst_opts_cnt is zero up front. If it is zero then > drop the packet since Destination Options processing is disabled. > > Similarly, in IPv6 hop-by-hop options processing function check if > net->ipv6.sysctl.max_hbh_opts_cnt is zero up front. If it is zero then > drop the packet since Hop-by-Hop Options processing is disabled. > > Signed-off-by: Tom Herbert > --- > net/ipv6/exthdrs.c | 18 ++++++++++-------- > 1 file changed, 10 insertions(+), 8 deletions(-) > > diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c > index 54088fa0c09d..b9d186784b96 100644 > --- a/net/ipv6/exthdrs.c > +++ b/net/ipv6/exthdrs.c > @@ -301,9 +301,11 @@ static int ipv6_destopt_rcv(struct sk_buff *skb) > #endif > struct dst_entry *dst = skb_dst(skb); > struct net *net = dev_net(skb->dev); > - int extlen; > + int extlen, max_opts_cnt; > > - if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) || > + max_opts_cnt = READ_ONCE(net->ipv6.sysctl.max_dst_opts_cnt); > + if (!max_opts_cnt || > + !pskb_may_pull(skb, skb_transport_offset(skb) + 8) || > !pskb_may_pull(skb, (skb_transport_offset(skb) + > ((skb_transport_header(skb)[1] + 1) << 3)))) { > __IP6_INC_STATS(dev_net(dst_dev(dst)), idev, > @@ -322,8 +324,7 @@ static int ipv6_destopt_rcv(struct sk_buff *skb) > dstbuf = opt->dst1; > #endif > > - if (ip6_parse_tlv(false, skb, > - READ_ONCE(net->ipv6.sysctl.max_dst_opts_cnt))) { > + if (ip6_parse_tlv(false, skb, max_opts_cnt)) { > skb->transport_header += extlen; > opt = IP6CB(skb); > #if IS_ENABLED(CONFIG_IPV6_MIP6) > @@ -1033,7 +1034,7 @@ int ipv6_parse_hopopts(struct sk_buff *skb) > { > struct inet6_skb_parm *opt = IP6CB(skb); > struct net *net = dev_net(skb->dev); > - int extlen; > + int extlen, max_opts_cnt; > > /* > * skb_network_header(skb) is equal to skb->data, and > @@ -1041,7 +1042,9 @@ int ipv6_parse_hopopts(struct sk_buff *skb) > * sizeof(struct ipv6hdr) by definition of > * hop-by-hop options. > */ > - if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) || > + max_opts_cnt = READ_ONCE(net->ipv6.sysctl.max_hbh_opts_cnt); > + if (!max_opts_cnt || > + !pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) || > !pskb_may_pull(skb, (sizeof(struct ipv6hdr) + > ((skb_transport_header(skb)[1] + 1) << 3)))) { > fail_and_free: > @@ -1054,8 +1057,7 @@ int ipv6_parse_hopopts(struct sk_buff *skb) > goto fail_and_free; > > opt->flags |= IP6SKB_HOPBYHOP; > - if (ip6_parse_tlv(true, skb, > - READ_ONCE(net->ipv6.sysctl.max_hbh_opts_cnt))) { > + if (ip6_parse_tlv(true, skb, max_opts_cnt)) { > skb->transport_header += extlen; > opt = IP6CB(skb); > opt->nhoff = sizeof(struct ipv6hdr); Reviewed-by: Justin Iurman