[PATCH 6.6.y 2/4] ipv4: adopt dst_dev, skb_dst_dev and skb_dst_dev_net[_rcu]
From: Miguel Gazquez (Schneider Electric)
Date: Mon Aug 31 2026 - 17:37:09 EST
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit a74fc62eec155ca5a6da8ff3856f3dc87fe24558 ]
Use the new helpers as a first step to deal with
potential dst->dev races.
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Link: https://patch.msgid.link/20250630121934.3399505-8-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
[ minor modifications to fix conflict ]
Signed-off-by: Miguel Gazquez (Schneider Electric) <miguel.gazquez@xxxxxxxxxxx>
---
include/net/inet_hashtables.h | 2 +-
include/net/ip.h | 11 ++++++-----
include/net/route.h | 2 +-
net/ipv4/icmp.c | 24 +++++++++++++-----------
net/ipv4/igmp.c | 2 +-
net/ipv4/ip_fragment.c | 2 +-
net/ipv4/ip_output.c | 4 ++--
net/ipv4/ip_vti.c | 4 ++--
net/ipv4/netfilter.c | 4 ++--
net/ipv4/route.c | 8 ++++----
net/ipv4/tcp_fastopen.c | 4 +++-
net/ipv4/tcp_ipv4.c | 3 ++-
net/ipv4/tcp_metrics.c | 8 ++++----
net/ipv4/xfrm4_output.c | 2 +-
14 files changed, 43 insertions(+), 37 deletions(-)
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index 8eeb3708f20b..21119e962f00 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -511,7 +511,7 @@ static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
const int sdif,
bool *refcounted)
{
- struct net *net = dev_net(skb_dst(skb)->dev);
+ struct net *net = skb_dst_dev_net(skb);
const struct iphdr *iph = ip_hdr(skb);
struct sock *sk;
diff --git a/include/net/ip.h b/include/net/ip.h
index bacdb4fecc89..f66dd581ba83 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -458,7 +458,7 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
bool forwarding)
{
const struct rtable *rt = container_of(dst, struct rtable, dst);
- struct net *net = dev_net(dst->dev);
+ struct net *net = dev_net(dst_dev(dst));
unsigned int mtu;
if (READ_ONCE(net->ipv4.sysctl_ip_fwd_use_pmtu) ||
@@ -474,7 +474,7 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
if (mtu)
goto out;
- mtu = READ_ONCE(dst->dev->mtu);
+ mtu = READ_ONCE(dst_dev(dst)->mtu);
if (unlikely(ip_mtu_locked(dst))) {
if (rt->rt_uses_gateway && mtu > 576)
@@ -490,16 +490,17 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
static inline unsigned int ip_skb_dst_mtu(struct sock *sk,
const struct sk_buff *skb)
{
+ const struct dst_entry *dst = skb_dst(skb);
unsigned int mtu;
if (!sk || !sk_fullsock(sk) || ip_sk_use_pmtu(sk)) {
bool forwarding = IPCB(skb)->flags & IPSKB_FORWARDED;
- return ip_dst_mtu_maybe_forward(skb_dst(skb), forwarding);
+ return ip_dst_mtu_maybe_forward(dst, forwarding);
}
- mtu = min(READ_ONCE(skb_dst(skb)->dev->mtu), IP_MAX_MTU);
- return mtu - lwtunnel_headroom(skb_dst(skb)->lwtstate, mtu);
+ mtu = min(READ_ONCE(dst_dev(dst)->mtu), IP_MAX_MTU);
+ return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
}
struct dst_metrics *ip_fib_metrics_init(struct nlattr *fc_mx, int fc_mx_len,
diff --git a/include/net/route.h b/include/net/route.h
index 1d5d975c1707..d443de683628 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -359,7 +359,7 @@ static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
const struct net *net;
rcu_read_lock();
- net = dev_net_rcu(dst->dev);
+ net = dev_net_rcu(dst_dev(dst));
hoplimit = READ_ONCE(net->ipv4.sysctl_ip_default_ttl);
rcu_read_unlock();
}
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 7c4c7b7fe384..f0c8c3366740 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -313,18 +313,20 @@ static bool icmpv4_xrlim_allow(struct net *net, struct rtable *rt,
{
struct dst_entry *dst = &rt->dst;
struct inet_peer *peer;
+ struct net_device *dev;
bool rc = true;
if (!apply_ratelimit)
return true;
/* No rate limit on loopback */
- if (dst->dev && (dst->dev->flags&IFF_LOOPBACK))
+ dev = dst_dev(dst);
+ if (dev && (dev->flags & IFF_LOOPBACK))
goto out;
rcu_read_lock();
peer = inet_getpeer_v4(net->ipv4.peers, fl4->daddr,
- l3mdev_master_ifindex_rcu(dst->dev));
+ l3mdev_master_ifindex_rcu(dev));
rc = inet_peer_xrlim_allow(peer,
READ_ONCE(net->ipv4.sysctl_icmp_ratelimit));
rcu_read_unlock();
@@ -472,13 +474,13 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
*/
static struct net_device *icmp_get_route_lookup_dev(struct sk_buff *skb)
{
- struct net_device *route_lookup_dev = NULL;
+ struct net_device *dev = skb->dev;
+ const struct dst_entry *dst;
- if (skb->dev)
- route_lookup_dev = skb->dev;
- else if (skb_dst(skb))
- route_lookup_dev = skb_dst(skb)->dev;
- return route_lookup_dev;
+ if (dev)
+ return dev;
+ dst = skb_dst(skb);
+ return dst ? dst_dev(dst) : NULL;
}
static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4,
@@ -911,7 +913,7 @@ static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
struct net *net;
u32 info = 0;
- net = dev_net_rcu(skb_dst(skb)->dev);
+ net = skb_dst_dev_net_rcu(skb);
/*
* Incomplete header ?
@@ -1054,7 +1056,7 @@ static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
struct icmp_bxm icmp_param;
struct net *net;
- net = dev_net_rcu(skb_dst(skb)->dev);
+ net = skb_dst_dev_net_rcu(skb);
/* should there be an ICMP stat for ignored echos? */
if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all))
return SKB_NOT_DROPPED_YET;
@@ -1231,7 +1233,7 @@ static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
return SKB_NOT_DROPPED_YET;
out_err:
- __ICMP_INC_STATS(dev_net_rcu(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
+ __ICMP_INC_STATS(skb_dst_dev_net_rcu(skb), ICMP_MIB_INERRORS);
return SKB_DROP_REASON_PKT_TOO_SMALL;
}
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 732804f3a0aa..8509e9473834 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -428,7 +428,7 @@ static int igmpv3_sendpack(struct sk_buff *skb)
pig->csum = ip_compute_csum(igmp_hdr(skb), igmplen);
- return ip_local_out(dev_net(skb_dst(skb)->dev), skb->sk, skb);
+ return ip_local_out(skb_dst_dev_net(skb), skb->sk, skb);
}
static int grec_size(struct ip_mc_list *pmc, int type, int gdel, int sdel)
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 8524f2ac2cf3..46b84d029205 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -470,7 +470,7 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb,
/* Process an incoming IP datagram fragment. */
int ip_defrag(struct net *net, struct sk_buff *skb, u32 user)
{
- struct net_device *dev = skb->dev ? : skb_dst(skb)->dev;
+ struct net_device *dev = skb->dev ? : skb_dst_dev(skb);
int vif = l3mdev_master_ifindex_rcu(dev);
struct ipq *qp;
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 150cdea8aacb..3bb198b2c101 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -116,7 +116,7 @@ int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
skb->protocol = htons(ETH_P_IP);
return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
- net, sk, skb, NULL, skb_dst(skb)->dev,
+ net, sk, skb, NULL, skb_dst_dev(skb),
dst_output);
}
@@ -199,7 +199,7 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
{
struct dst_entry *dst = skb_dst(skb);
struct rtable *rt = (struct rtable *)dst;
- struct net_device *dev = dst->dev;
+ struct net_device *dev = dst_dev(dst);
unsigned int hh_len = LL_RESERVED_SPACE(dev);
struct neighbour *neigh;
bool is_v6gw = false;
diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
index 02744447e435..cd61a417c44d 100644
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -226,7 +226,7 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev,
goto tx_error_icmp;
}
- tdev = dst->dev;
+ tdev = dst_dev(dst);
if (tdev == dev) {
dst_release(dst);
@@ -256,7 +256,7 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev,
xmit:
skb_scrub_packet(skb, !net_eq(tunnel->net, dev_net(dev)));
skb_dst_set(skb, dst);
- skb->dev = skb_dst(skb)->dev;
+ skb->dev = skb_dst_dev(skb);
err = dst_output(tunnel->net, skb->sk, skb);
if (net_xmit_eval(err) == 0)
diff --git a/net/ipv4/netfilter.c b/net/ipv4/netfilter.c
index bd135165482a..c450509d6efd 100644
--- a/net/ipv4/netfilter.c
+++ b/net/ipv4/netfilter.c
@@ -19,12 +19,12 @@
/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
int ip_route_me_harder(struct net *net, struct sock *sk, struct sk_buff *skb, unsigned int addr_type)
{
+ struct net_device *dev = skb_dst_dev(skb);
const struct iphdr *iph = ip_hdr(skb);
struct rtable *rt;
struct flowi4 fl4 = {};
__be32 saddr = iph->saddr;
__u8 flags;
- struct net_device *dev = skb_dst(skb)->dev;
struct flow_keys flkeys;
unsigned int hh_len;
@@ -73,7 +73,7 @@ int ip_route_me_harder(struct net *net, struct sock *sk, struct sk_buff *skb, un
#endif
/* Change in oif may mean change in hh_len. */
- hh_len = skb_dst(skb)->dev->hard_header_len;
+ hh_len = skb_dst_dev(skb)->hard_header_len;
if (skb_headroom(skb) < hh_len &&
pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
0, GFP_ATOMIC))
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 789953096c80..5010a9a75418 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -416,7 +416,7 @@ static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
const void *daddr)
{
const struct rtable *rt = container_of(dst, struct rtable, dst);
- struct net_device *dev = dst->dev;
+ struct net_device *dev = dst_dev(dst);
struct neighbour *n;
rcu_read_lock();
@@ -443,7 +443,7 @@ static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr)
{
const struct rtable *rt = container_of(dst, struct rtable, dst);
- struct net_device *dev = dst->dev;
+ struct net_device *dev = dst_dev(dst);
const __be32 *pkey = daddr;
if (rt->rt_gw_family == AF_INET) {
@@ -1069,7 +1069,7 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
return;
rcu_read_lock();
- net = dev_net_rcu(dst->dev);
+ net = dev_net_rcu(dst_dev(dst));
if (mtu < net->ipv4.ip_rt_min_pmtu) {
lock = true;
mtu = min(old_mtu, net->ipv4.ip_rt_min_pmtu);
@@ -1367,7 +1367,7 @@ static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
struct net *net;
rcu_read_lock();
- net = dev_net_rcu(dst->dev);
+ net = dev_net_rcu(dst_dev(dst));
advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size,
net->ipv4.ip_rt_min_advmss);
rcu_read_unlock();
diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index 408985eb74ee..86c995dc1c5e 100644
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -558,6 +558,7 @@ bool tcp_fastopen_active_should_disable(struct sock *sk)
void tcp_fastopen_active_disable_ofo_check(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
+ struct net_device *dev;
struct dst_entry *dst;
struct sk_buff *skb;
@@ -575,7 +576,8 @@ void tcp_fastopen_active_disable_ofo_check(struct sock *sk)
} else if (tp->syn_fastopen_ch &&
atomic_read(&sock_net(sk)->ipv4.tfo_active_disable_times)) {
dst = sk_dst_get(sk);
- if (!(dst && dst->dev && (dst->dev->flags & IFF_LOOPBACK)))
+ dev = dst ? dst_dev(dst) : NULL;
+ if (!(dev && (dev->flags & IFF_LOOPBACK)))
atomic_set(&sock_net(sk)->ipv4.tfo_active_disable_times, 0);
dst_release(dst);
}
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 3f9e1cfde008..3055478860c1 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -732,7 +732,8 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
arg.iov[0].iov_base = (unsigned char *)&rep;
arg.iov[0].iov_len = sizeof(rep.th);
- net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
+ net = sk ? sock_net(sk) : skb_dst_dev_net(skb);
+
#ifdef CONFIG_TCP_MD5SIG
rcu_read_lock();
hash_location = tcp_parse_md5sig_option(th);
diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
index e0883ba709b0..49983d864e4f 100644
--- a/net/ipv4/tcp_metrics.c
+++ b/net/ipv4/tcp_metrics.c
@@ -166,11 +166,11 @@ static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
unsigned int hash)
{
struct tcp_metrics_block *tm;
- struct net *net;
bool reclaim = false;
+ struct net *net;
spin_lock_bh(&tcp_metrics_lock);
- net = dev_net(dst->dev);
+ net = dev_net(dst_dev(dst));
/* While waiting for the spin-lock the cache might have been populated
* with this entry and so we have to check again.
@@ -273,7 +273,7 @@ static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
return NULL;
}
- net = dev_net(dst->dev);
+ net = dev_net(dst_dev(dst));
hash ^= net_hash_mix(net);
hash = hash_32(hash, tcp_metrics_hash_log);
@@ -318,7 +318,7 @@ static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
else
return NULL;
- net = dev_net(dst->dev);
+ net = dev_net(dst_dev(dst));
hash ^= net_hash_mix(net);
hash = hash_32(hash, tcp_metrics_hash_log);
diff --git a/net/ipv4/xfrm4_output.c b/net/ipv4/xfrm4_output.c
index 3cff51ba72bb..0ae67d537499 100644
--- a/net/ipv4/xfrm4_output.c
+++ b/net/ipv4/xfrm4_output.c
@@ -31,7 +31,7 @@ static int __xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
int xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
- net, sk, skb, skb->dev, skb_dst(skb)->dev,
+ net, sk, skb, skb->dev, skb_dst_dev(skb),
__xfrm4_output,
!(IPCB(skb)->flags & IPSKB_REROUTED));
}
--
2.55.0