This is a note to let you know that I've just added the patch titled
ipv6: use skb_expand_head in ip6_finish_output2
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipv6-use-skb_expand_head-in-ip6_finish_output2.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 095395a558920d5580a0fcf7b7575a72ee608892
Author: Vasily Averin <vasily.averin@xxxxxxxxx>
Date: Tue Dec 24 21:16:22 2024 -0800
ipv6: use skb_expand_head in ip6_finish_output2
[ Upstream commit e415ed3a4b8b246ee5e9d109ff5153efcf96b9f2 ]
Unlike skb_realloc_headroom, new helper skb_expand_head does not allocate
a new skb if possible.
Additionally this patch replaces commonly used dereferencing with variables.
Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
(cherry picked from commit e415ed3a4b8b246ee5e9d109ff5153efcf96b9f2)
Signed-off-by: Harshvardhan Jha <harshvardhan.j.jha@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index a34a562b0954..906d1be9dee8 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -59,46 +59,29 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
{
struct dst_entry *dst = skb_dst(skb);
struct net_device *dev = dst->dev;
+ struct inet6_dev *idev = ip6_dst_idev(dst);
unsigned int hh_len = LL_RESERVED_SPACE(dev);
- int delta = hh_len - skb_headroom(skb);
- const struct in6_addr *nexthop;
+ const struct in6_addr *daddr, *nexthop;
+ struct ipv6hdr *hdr;
struct neighbour *neigh;
int ret;
/* Be paranoid, rather than too clever. */
- if (unlikely(delta > 0) && dev->header_ops) {
- /* pskb_expand_head() might crash, if skb is shared */
- if (skb_shared(skb)) {
- struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC);
-
- if (likely(nskb)) {
- if (skb->sk)
- skb_set_owner_w(nskb, skb->sk);
- consume_skb(skb);
- } else {
- kfree_skb(skb);
- }
- skb = nskb;
- }
- if (skb &&
- pskb_expand_head(skb, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {
- kfree_skb(skb);
- skb = NULL;
- }
+ if (unlikely(hh_len > skb_headroom(skb)) && dev->header_ops) {
+ skb = skb_expand_head(skb, hh_len);
if (!skb) {
- IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTDISCARDS);
+ IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS);
return -ENOMEM;
}
}
- if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) {
- struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));
-
+ hdr = ipv6_hdr(skb);
+ daddr = &hdr->daddr;
+ if (ipv6_addr_is_multicast(daddr)) {
if (!(dev->flags & IFF_LOOPBACK) && sk_mc_loop(sk) &&
((mroute6_is_socket(net, skb) &&
!(IP6CB(skb)->flags & IP6SKB_FORWARDED)) ||
- ipv6_chk_mcast_addr(dev, &ipv6_hdr(skb)->daddr,
- &ipv6_hdr(skb)->saddr))) {
+ ipv6_chk_mcast_addr(dev, daddr, &hdr->saddr))) {
struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
/* Do not check for IFF_ALLMULTI; multicast routing
@@ -109,7 +92,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
net, sk, newskb, NULL, newskb->dev,
dev_loopback_xmit);
- if (ipv6_hdr(skb)->hop_limit == 0) {
+ if (hdr->hop_limit == 0) {
IP6_INC_STATS(net, idev,
IPSTATS_MIB_OUTDISCARDS);
kfree_skb(skb);
@@ -118,9 +101,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
}
IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUTMCAST, skb->len);
-
- if (IPV6_ADDR_MC_SCOPE(&ipv6_hdr(skb)->daddr) <=
- IPV6_ADDR_SCOPE_NODELOCAL &&
+ if (IPV6_ADDR_MC_SCOPE(daddr) <= IPV6_ADDR_SCOPE_NODELOCAL &&
!(dev->flags & IFF_LOOPBACK)) {
kfree_skb(skb);
return 0;
@@ -135,10 +116,10 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
}
rcu_read_lock_bh();
- nexthop = rt6_nexthop((struct rt6_info *)dst, &ipv6_hdr(skb)->daddr);
- neigh = __ipv6_neigh_lookup_noref(dst->dev, nexthop);
+ nexthop = rt6_nexthop((struct rt6_info *)dst, daddr);
+ neigh = __ipv6_neigh_lookup_noref(dev, nexthop);
if (unlikely(!neigh))
- neigh = __neigh_create(&nd_tbl, nexthop, dst->dev, false);
+ neigh = __neigh_create(&nd_tbl, nexthop, dev, false);
if (!IS_ERR(neigh)) {
sock_confirm_neigh(skb, neigh);
ret = neigh_output(neigh, skb, false);
@@ -147,7 +128,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
}
rcu_read_unlock_bh();
- IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
+ IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTNOROUTES);
kfree_skb(skb);
return -EINVAL;
}
