[PATCH net-next 3/4] psp: allow drivers to omit tx key add/del ops

[Daniel Zahka <daniel.zahka@gmail.com>]

Drivers that don't use an SADB for tx key storage don't have a use
for psp_dev_ops::tx_key_add and psp_dev_ops::tx_key_del.

Allowing drivers to leave these as NULL gives PSP core a simple way to
determine whether a driver utilizes an SADB, which in turn could
affect how PSP core chooses to handle certain situations.

For example:
- deciding if tx key deletion needs to be delayed during a rekeying
  event to avoid in-flight packets using old key handles.
- choosing whether or not to report device stats like SADB usage to
  userspace, which only make sense if the driver uses on-device key
  storage.

Signed-off-by: Daniel Zahka <daniel.zahka@gmail.com>
---
 include/net/psp/types.h | 4 ++++
 net/psp/psp.h           | 8 +++++++-
 net/psp/psp_main.c      | 6 +++---
 net/psp/psp_sock.c      | 8 +++++---
 4 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/include/net/psp/types.h b/include/net/psp/types.h
index 87991a1ea02d..b8905efbd604 100644
--- a/include/net/psp/types.h
+++ b/include/net/psp/types.h
@@ -219,12 +219,16 @@ struct psp_dev_ops {
 	 * @tx_key_add: add a Tx key to the device
 	 * Install an association in the device. Core will allocate space
 	 * for the driver to use at drv_data.
+	 * Can be left NULL if device does not store Tx keys and @tx_key_del
+	 * is also NULL.
 	 */
 	int (*tx_key_add)(struct psp_dev *psd, struct psp_assoc *pas,
 			  struct netlink_ext_ack *extack);
 	/**
 	 * @tx_key_del: remove a Tx key from the device
 	 * Remove an association from the device.
+	 * Can be left NULL if device does not store Tx keys and @tx_key_add
+	 * is also NULL.
 	 */
 	void (*tx_key_del)(struct psp_dev *psd, struct psp_assoc *pas);
 
diff --git a/net/psp/psp.h b/net/psp/psp.h
index 8acf9ca84b55..bbb39e2f5b0a 100644
--- a/net/psp/psp.h
+++ b/net/psp/psp.h
@@ -53,10 +53,16 @@ static inline bool psp_dev_is_registered(struct psp_dev *psd)
 	return !!psd->ops;
 }
 
+static inline bool psp_dev_has_sadb(struct psp_dev *psd)
+{
+	lockdep_assert_held(&psd->lock);
+	return !!psd->ops->tx_key_del;
+}
+
 static inline bool psp_assoc_needs_tx_key_del(struct psp_assoc *pas)
 {
 	lockdep_assert_held(&pas->psd->lock);
-	return pas->tx.spi;
+	return psp_dev_has_sadb(pas->psd) && pas->tx.spi;
 }
 
 #endif /* __PSP_PSP_H */
diff --git a/net/psp/psp_main.c b/net/psp/psp_main.c
index 2556f0d46ef4..91473f96ad21 100644
--- a/net/psp/psp_main.c
+++ b/net/psp/psp_main.c
@@ -68,9 +68,9 @@ psp_dev_create(struct net_device *netdev,
 		    !psd_ops->set_config ||
 		    !psd_ops->key_rotate ||
 		    !psd_ops->rx_spi_alloc ||
-		    !psd_ops->tx_key_add ||
-		    !psd_ops->tx_key_del ||
-		    !psd_ops->get_stats))
+		    !psd_ops->get_stats ||
+		    (!psd_ops->tx_key_add != !psd_ops->tx_key_del) ||
+		    (psd_caps->assoc_drv_spc && !psd_ops->tx_key_add)))
 		return ERR_PTR(-EINVAL);
 
 	psd = kzalloc_obj(*psd);
diff --git a/net/psp/psp_sock.c b/net/psp/psp_sock.c
index 36eb06faa54a..6a4becc38b55 100644
--- a/net/psp/psp_sock.c
+++ b/net/psp/psp_sock.c
@@ -181,9 +181,11 @@ static int psp_assoc_set_tx(struct psp_dev *psd, struct psp_assoc *pas,
 {
 	int err;
 
-	err = psp_dev_tx_key_add(psd, pas, key, extack);
-	if (err)
-		return err;
+	if (psp_dev_has_sadb(psd)) {
+		err = psp_dev_tx_key_add(psd, pas, key, extack);
+		if (err)
+			return err;
+	}
 
 	memcpy(&pas->tx, key, sizeof(*key));
 	return 0;

-- 
2.52.0