On Fri, Apr 11, 2025 at 10:49:58AM +0300, Cosmin Ratiu wrote:
> Refactor the bonding ipsec offload operations to fix a number of
> long-standing control plane races between state migration and user
> deletion and a few other issues.
>
> xfrm state deletion can happen concurrently with
> bond_change_active_slave() operation. This manifests itself as a
> bond_ipsec_del_sa() call with x->lock held, followed by a
> bond_ipsec_free_sa() a bit later from a wq. The alternate path of
> these calls coming from xfrm_dev_state_flush() can't happen, as that
> needs the RTNL lock and bond_change_active_slave() already holds it.
>
> 1. bond_ipsec_del_sa_all() might call xdo_dev_state_delete() a second
> time on an xfrm state that was concurrently killed. This is bad.
> 2. bond_ipsec_add_sa_all() can add a state on the new device, but
> pending bond_ipsec_free_sa() calls from the old device will then hit
> the WARN_ON() and then, worse, call xdo_dev_state_free() on the new
> device without a corresponding xdo_dev_state_delete().
> 3. Resolve a sleeping in atomic context introduced by the mentioned
> "Fixes" commit.
>
> bond_ipsec_del_sa_all() and bond_ipsec_add_sa_all() now acquire x->lock
> and check for x->km.state to help with problems 1 and 2. And since
> xso.real_dev is now a private pointer managed by the bonding driver in
> xfrm state, make better use of it to fully fix problems 1 and 2. In
> bond_ipsec_del_sa_all(), set xso.real_dev to NULL while holding both the
> mutex and x->lock, which makes sure that neither bond_ipsec_del_sa() nor
> bond_ipsec_free_sa() could run concurrently.
>
> Fix problem 3 by moving the list cleanup (which requires the mutex) from
> bond_ipsec_del_sa() (called from atomic context) to bond_ipsec_free_sa()
>
> Finally, simplify bond_ipsec_del_sa() and bond_ipsec_free_sa() by using
> xso->real_dev directly, since it's now protected by locks and can be
> trusted to always reflect the offload device.
>
> Fixes: 2aeeef906d5a ("bonding: change ipsec_lock from spin lock to mutex")
> Signed-off-by: Cosmin Ratiu <[email protected]>
> Reviewed-by: Leon Romanovsky <[email protected]>
> ---
> drivers/net/bonding/bond_main.c | 82 +++++++++++++++------------------
> include/net/xfrm.h | 7 ++-
> 2 files changed, 41 insertions(+), 48 deletions(-)
>
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 14f7c9712ad4..8ed8c29659a0 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -545,7 +545,20 @@ static void bond_ipsec_add_sa_all(struct bonding *bond)
> slave_warn(bond_dev, real_dev, "%s: failed to add
> SA\n", __func__);
> continue;
> }
> +
> + spin_lock_bh(&ipsec->xs->lock);
> + /* xs might have been killed by the user during the migration
> + * to the new dev, but bond_ipsec_del_sa() should have done
> + * nothing, as xso.real_dev is NULL.
> + * Delete it from the device we just added it to. The pending
> + * bond_ipsec_free_sa() call will do the rest of the cleanup.
> + */
> + if (ipsec->xs->km.state == XFRM_STATE_DEAD &&
> + real_dev->xfrmdev_ops->xdo_dev_state_delete)
> + real_dev->xfrmdev_ops->xdo_dev_state_delete(real_dev,
> + ipsec->xs);
> ipsec->xs->xso.real_dev = real_dev;
> + spin_unlock_bh(&ipsec->xs->lock);
> }
> out:
> mutex_unlock(&bond->ipsec_lock);
> @@ -560,48 +573,20 @@ static void bond_ipsec_del_sa(struct net_device
> *bond_dev,
> struct xfrm_state *xs)
> {
> struct net_device *real_dev;
> - netdevice_tracker tracker;
> - struct bond_ipsec *ipsec;
> - struct bonding *bond;
> - struct slave *slave;
>
> - if (!bond_dev)
> + if (!bond_dev || !xs->xso.real_dev)
> return;
>
> - rcu_read_lock();
> - bond = netdev_priv(bond_dev);
> - slave = rcu_dereference(bond->curr_active_slave);
> - real_dev = slave ? slave->dev : NULL;
> - netdev_hold(real_dev, &tracker, GFP_ATOMIC);
> - rcu_read_unlock();
> -
> - if (!slave)
> - goto out;
> -
> - if (!xs->xso.real_dev)
> - goto out;
> -
> - WARN_ON(xs->xso.real_dev != real_dev);
> + real_dev = xs->xso.real_dev;
>
> if (!real_dev->xfrmdev_ops ||
> !real_dev->xfrmdev_ops->xdo_dev_state_delete ||
> netif_is_bond_master(real_dev)) {
> slave_warn(bond_dev, real_dev, "%s: no slave
> xdo_dev_state_delete\n", __func__);
> - goto out;
> + return;
> }
>
> real_dev->xfrmdev_ops->xdo_dev_state_delete(real_dev, xs);
> -out:
> - netdev_put(real_dev, &tracker);
> - mutex_lock(&bond->ipsec_lock);
> - list_for_each_entry(ipsec, &bond->ipsec_list, list) {
> - if (ipsec->xs == xs) {
> - list_del(&ipsec->list);
> - kfree(ipsec);
> - break;
> - }
> - }
> - mutex_unlock(&bond->ipsec_lock);
> }
>
> static void bond_ipsec_del_sa_all(struct bonding *bond)
> @@ -629,9 +614,15 @@ static void bond_ipsec_del_sa_all(struct bonding *bond)
> __func__);
> continue;
> }
> +
> + spin_lock_bh(&ipsec->xs->lock);
> ipsec->xs->xso.real_dev = NULL;
> - real_dev->xfrmdev_ops->xdo_dev_state_delete(real_dev,
> - ipsec->xs);
> + /* Don't double delete states killed by the user. */
> + if (ipsec->xs->km.state != XFRM_STATE_DEAD)
> + real_dev->xfrmdev_ops->xdo_dev_state_delete(real_dev,
> + ipsec->xs);
> + spin_unlock_bh(&ipsec->xs->lock);
> +
> if (real_dev->xfrmdev_ops->xdo_dev_state_free)
> real_dev->xfrmdev_ops->xdo_dev_state_free(real_dev,
> ipsec->xs);
> @@ -643,34 +634,33 @@ static void bond_ipsec_free_sa(struct net_device
> *bond_dev,
> struct xfrm_state *xs)
> {
> struct net_device *real_dev;
> - netdevice_tracker tracker;
> + struct bond_ipsec *ipsec;
> struct bonding *bond;
> - struct slave *slave;
>
> if (!bond_dev)
> return;
>
> - rcu_read_lock();
> bond = netdev_priv(bond_dev);
> - slave = rcu_dereference(bond->curr_active_slave);
> - real_dev = slave ? slave->dev : NULL;
> - netdev_hold(real_dev, &tracker, GFP_ATOMIC);
> - rcu_read_unlock();
> -
> - if (!slave)
> - goto out;
>
> + mutex_lock(&bond->ipsec_lock);
> if (!xs->xso.real_dev)
> goto out;
>
> - WARN_ON(xs->xso.real_dev != real_dev);
> + real_dev = xs->xso.real_dev;
>
> xs->xso.real_dev = NULL;
> - if (real_dev && real_dev->xfrmdev_ops &&
> + if (real_dev->xfrmdev_ops &&
> real_dev->xfrmdev_ops->xdo_dev_state_free)
> real_dev->xfrmdev_ops->xdo_dev_state_free(real_dev, xs);
> out:
> - netdev_put(real_dev, &tracker);
> + list_for_each_entry(ipsec, &bond->ipsec_list, list) {
> + if (ipsec->xs == xs) {
> + list_del(&ipsec->list);
> + kfree(ipsec);
> + break;
> + }
> + }
> + mutex_unlock(&bond->ipsec_lock);
> }
>
> /**
> diff --git a/include/net/xfrm.h b/include/net/xfrm.h
> index 3d2f6c879311..b7e8f3f49627 100644
> --- a/include/net/xfrm.h
> +++ b/include/net/xfrm.h
> @@ -154,8 +154,11 @@ struct xfrm_dev_offload {
> */
> struct net_device *dev;
> netdevice_tracker dev_tracker;
> - /* This is a private pointer used by the bonding driver.
> - * Device drivers should not use it.
> + /* This is a private pointer used by the bonding driver (and eventually
> + * should be moved there). Device drivers should not use it.
> + * Protected by xfrm_state.lock AND bond.ipsec_lock in most cases,
> + * except in the .xdo_dev_state_del() flow, where only xfrm_state.lock
> + * is held.
> */
> struct net_device *real_dev;
> unsigned long offload_handle;
> --
> 2.45.0
>
Tested-by: Hangbin Liu <[email protected]>
Reviewed-by: Hangbin Liu <[email protected]>
