[PATCH v3 net-next 08/14] ipv6: Add hop-by-hop header to jumbograms in ip6_output
From: Eric Dumazet <hidden>
Date: 2022-03-10 00:29:17
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
From: Coco Li <redacted> Instead of simply forcing a 0 payload_len in IPv6 header, implement RFC 2675 and insert a custom extension header. Note that only TCP stack is currently potentially generating jumbograms, and that this extension header is purely local, it wont be sent on a physical link. This is needed so that packet capture (tcpdump and friends) can properly dissect these large packets. Signed-off-by: Coco Li <redacted> Signed-off-by: Eric Dumazet <edumazet@google.com> --- include/linux/ipv6.h | 1 + net/ipv6/ip6_output.c | 22 ++++++++++++++++++++-- 2 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 16870f86c74d3d1f5dfb7edac1e7db85f1ef6755..93b273db1c9926aba4199f486ce90778311916f5 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h@@ -144,6 +144,7 @@ struct inet6_skb_parm { #define IP6SKB_L3SLAVE 64 #define IP6SKB_JUMBOGRAM 128 #define IP6SKB_SEG6 256 +#define IP6SKB_FAKEJUMBO 512 }; #if defined(CONFIG_NET_L3_MASTER_DEV)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index e69fac576970a9b85fb68aa02822c0e2df67e1a2..941ceff83b616cec11c6bb7ccaf81bc041f8d9cc 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c@@ -180,7 +180,9 @@ static int __ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff #endif mtu = ip6_skb_dst_mtu(skb); - if (skb_is_gso(skb) && !skb_gso_validate_network_len(skb, mtu)) + if (skb_is_gso(skb) && + !(IP6CB(skb)->flags & IP6SKB_FAKEJUMBO) && + !skb_gso_validate_network_len(skb, mtu)) return ip6_finish_output_gso_slowpath_drop(net, sk, skb, mtu); if ((skb->len > mtu && !skb_is_gso(skb)) ||
@@ -251,6 +253,8 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, struct dst_entry *dst = skb_dst(skb); struct net_device *dev = dst->dev; struct inet6_dev *idev = ip6_dst_idev(dst); + struct hop_jumbo_hdr *hop_jumbo; + int hoplen = sizeof(*hop_jumbo); unsigned int head_room; struct ipv6hdr *hdr; u8 proto = fl6->flowi6_proto;
@@ -258,7 +262,7 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, int hlimit = -1; u32 mtu; - head_room = sizeof(struct ipv6hdr) + LL_RESERVED_SPACE(dev); + head_room = sizeof(struct ipv6hdr) + hoplen + LL_RESERVED_SPACE(dev); if (opt) head_room += opt->opt_nflen + opt->opt_flen;
@@ -281,6 +285,20 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, &fl6->saddr); } + if (unlikely(seg_len > IPV6_MAXPLEN)) { + hop_jumbo = skb_push(skb, hoplen); + + hop_jumbo->nexthdr = proto; + hop_jumbo->hdrlen = 0; + hop_jumbo->tlv_type = IPV6_TLV_JUMBO; + hop_jumbo->tlv_len = 4; + hop_jumbo->jumbo_payload_len = htonl(seg_len + hoplen); + + proto = IPPROTO_HOPOPTS; + seg_len = 0; + IP6CB(skb)->flags |= IP6SKB_FAKEJUMBO; + } + skb_push(skb, sizeof(struct ipv6hdr)); skb_reset_network_header(skb); hdr = ipv6_hdr(skb);
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2.35.1.616.g0bdcbb4464-goog