diff options
| author | Eric Dumazet <edumazet@google.com> | 2025-02-05 15:51:11 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-02-06 16:14:14 -0800 |
| commit | 071d8012869b6af352acca346ade13e7be90a49f (patch) | |
| tree | c9c4be8179e4ec310f3c0ca713cc2ade8214c233 | |
| parent | 469308552ca4560176cfc100e7ca84add1bebd7c (diff) | |
ipv4: use RCU protection in ip_dst_mtu_maybe_forward()
ip_dst_mtu_maybe_forward() must use RCU protection to make
sure the net structure it reads does not disappear.
Fixes: f87c10a8aa1e8 ("ipv4: introduce ip_dst_mtu_maybe_forward and protect forwarding path against pmtu spoofing")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250205155120.1676781-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | include/net/ip.h | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/include/net/ip.h b/include/net/ip.h index 9f5e33e371fc..ba7b43447775 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -471,9 +471,12 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst, bool forwarding) { const struct rtable *rt = dst_rtable(dst); - struct net *net = dev_net(dst->dev); - unsigned int mtu; + unsigned int mtu, res; + struct net *net; + + rcu_read_lock(); + net = dev_net_rcu(dst->dev); if (READ_ONCE(net->ipv4.sysctl_ip_fwd_use_pmtu) || ip_mtu_locked(dst) || !forwarding) { @@ -497,7 +500,11 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst, out: mtu = min_t(unsigned int, mtu, IP_MAX_MTU); - return mtu - lwtunnel_headroom(dst->lwtstate, mtu); + res = mtu - lwtunnel_headroom(dst->lwtstate, mtu); + + rcu_read_unlock(); + + return res; } static inline unsigned int ip_skb_dst_mtu(struct sock *sk, |