[PATCH net-next v7 01/10] ipv6: Check of max HBH or DestOp sysctl is zero and drop if it is
From: Tom Herbert <hidden>
Date: 2026-02-04 22:53:01
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
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 <redacted> Reviewed-by: Justin Iurman <justin.iurman@gmail.com> --- 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 209fdf1b1aa9..6cc18f35216f 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);
--
2.43.0