6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 99a2ace61b211b0be861b07fbaa062fca4b58879 ] Use RCU to protect accesses to dst->dev from sk_setup_caps() and sk_dst_gso_max_size(). Also use dst_dev_rcu() in ip6_dst_mtu_maybe_forward(), and ip_dst_mtu_maybe_forward(). ip4_dst_hoplimit() can use dst_dev_net_rcu(). Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20250828195823.3958522-6-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- include/net/ip.h | 16 ++++++++++++---- include/net/ip6_route.h | 2 +- include/net/route.h | 2 +- net/core/sock.c | 16 ++++++++++------ 4 files changed, 24 insertions(+), 12 deletions(-) diff --git a/include/net/ip.h b/include/net/ip.h index 32825e2ac43d3..775185fe552f8 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -465,9 +465,14 @@ 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(dst)); - unsigned int mtu; + const struct net_device *dev; + unsigned int mtu, res; + struct net *net; + + rcu_read_lock(); + dev = dst_dev_rcu(dst); + net = dev_net_rcu(dev); if (READ_ONCE(net->ipv4.sysctl_ip_fwd_use_pmtu) || ip_mtu_locked(dst) || !forwarding) { @@ -481,7 +486,7 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst, if (mtu) goto out; - mtu = READ_ONCE(dst_dev(dst)->mtu); + mtu = READ_ONCE(dev->mtu); if (unlikely(ip_mtu_locked(dst))) { if (rt->rt_uses_gateway && mtu > 576) @@ -490,8 +495,11 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst, out: mtu = min_t(unsigned int, mtu, IP_MAX_MTU); + res = mtu - lwtunnel_headroom(dst->lwtstate, mtu); - return mtu - lwtunnel_headroom(dst->lwtstate, mtu); + rcu_read_unlock(); + + return res; } static inline unsigned int ip_skb_dst_mtu(struct sock *sk, diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h index 211d1ef8ab421..d5f3b842dd0a7 100644 --- a/include/net/ip6_route.h +++ b/include/net/ip6_route.h @@ -333,7 +333,7 @@ static inline unsigned int ip6_dst_mtu_maybe_forward(const struct dst_entry *dst mtu = IPV6_MIN_MTU; rcu_read_lock(); - idev = __in6_dev_get(dst->dev); + idev = __in6_dev_get(dst_dev_rcu(dst)); if (idev) mtu = idev->cnf.mtu6; rcu_read_unlock(); diff --git a/include/net/route.h b/include/net/route.h index d443de683628e..7f37b8b96c920 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(dst)); + net = dst_dev_net_rcu(dst); hoplimit = READ_ONCE(net->ipv4.sysctl_ip_default_ttl); rcu_read_unlock(); } diff --git a/net/core/sock.c b/net/core/sock.c index 057ec36aa4710..3aec06256f6ba 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2444,7 +2444,7 @@ void sk_free_unlock_clone(struct sock *sk) } EXPORT_SYMBOL_GPL(sk_free_unlock_clone); -static u32 sk_dst_gso_max_size(struct sock *sk, struct dst_entry *dst) +static u32 sk_dst_gso_max_size(struct sock *sk, const struct net_device *dev) { bool is_ipv6 = false; u32 max_size; @@ -2454,8 +2454,8 @@ static u32 sk_dst_gso_max_size(struct sock *sk, struct dst_entry *dst) !ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr)); #endif /* pairs with the WRITE_ONCE() in netif_set_gso(_ipv4)_max_size() */ - max_size = is_ipv6 ? READ_ONCE(dst_dev(dst)->gso_max_size) : - READ_ONCE(dst_dev(dst)->gso_ipv4_max_size); + max_size = is_ipv6 ? READ_ONCE(dev->gso_max_size) : + READ_ONCE(dev->gso_ipv4_max_size); if (max_size > GSO_LEGACY_MAX_SIZE && !sk_is_tcp(sk)) max_size = GSO_LEGACY_MAX_SIZE; @@ -2464,9 +2464,12 @@ static u32 sk_dst_gso_max_size(struct sock *sk, struct dst_entry *dst) void sk_setup_caps(struct sock *sk, struct dst_entry *dst) { + const struct net_device *dev; u32 max_segs = 1; - sk->sk_route_caps = dst_dev(dst)->features; + rcu_read_lock(); + dev = dst_dev_rcu(dst); + sk->sk_route_caps = dev->features; if (sk_is_tcp(sk)) sk->sk_route_caps |= NETIF_F_GSO; if (sk->sk_route_caps & NETIF_F_GSO) @@ -2478,13 +2481,14 @@ void sk_setup_caps(struct sock *sk, struct dst_entry *dst) sk->sk_route_caps &= ~NETIF_F_GSO_MASK; } else { sk->sk_route_caps |= NETIF_F_SG | NETIF_F_HW_CSUM; - sk->sk_gso_max_size = sk_dst_gso_max_size(sk, dst); + sk->sk_gso_max_size = sk_dst_gso_max_size(sk, dev); /* pairs with the WRITE_ONCE() in netif_set_gso_max_segs() */ - max_segs = max_t(u32, READ_ONCE(dst_dev(dst)->gso_max_segs), 1); + max_segs = max_t(u32, READ_ONCE(dev->gso_max_segs), 1); } } sk->sk_gso_max_segs = max_segs; sk_dst_set(sk, dst); + rcu_read_unlock(); } EXPORT_SYMBOL_GPL(sk_setup_caps); -- 2.53.0