From: Emeel Hakim <ehakim@nvidia.com>

This adds support for configuring Macsec offload through the
netlink layer by:
- Considering IFLA_MACSEC_OFFLOAD in macsec_fill_info.
- Handling IFLA_MACSEC_OFFLOAD in macsec_changelink.
- Adding IFLA_MACSEC_OFFLOAD to the netlink policy.
- Adjusting macsec_get_size.

Example for setting offload for a macsec device
    ip link set macsec0 type macsec offload mac

Signed-off-by: Emeel Hakim <ehakim@nvidia.com>
---
 drivers/net/macsec.c | 66 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 64 insertions(+), 2 deletions(-)

diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
index d73b9d535b7a..d27b737a6deb 100644
--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -3698,6 +3698,7 @@ static const struct nla_policy macsec_rtnl_policy[IFLA_MACSEC_MAX + 1] = {
 	[IFLA_MACSEC_SCB] = { .type = NLA_U8 },
 	[IFLA_MACSEC_REPLAY_PROTECT] = { .type = NLA_U8 },
 	[IFLA_MACSEC_VALIDATION] = { .type = NLA_U8 },
+	[IFLA_MACSEC_OFFLOAD] = { .type = NLA_U8 },
 };
 
 static void macsec_free_netdev(struct net_device *dev)
@@ -3803,6 +3804,54 @@ static int macsec_changelink_common(struct net_device *dev,
 	return 0;
 }
 
+static int macsec_changelink_upd_offload(struct net_device *dev, struct nlattr *data[])
+{
+	enum macsec_offload offload, prev_offload;
+	const struct macsec_ops *ops;
+	struct macsec_context ctx;
+	struct macsec_dev *macsec;
+	int ret = 0;
+
+	macsec = macsec_priv(dev);
+	offload = nla_get_u8(data[IFLA_MACSEC_OFFLOAD]);
+
+	/* Check if the offloading mode is supported by the underlying layers */
+	if (offload != MACSEC_OFFLOAD_OFF &&
+	    !macsec_check_offload(offload, macsec))
+		return -EOPNOTSUPP;
+
+	/* Check if the net device is busy. */
+	if (netif_running(dev))
+		return -EBUSY;
+
+	if (macsec->offload == offload)
+		return 0;
+
+	prev_offload = macsec->offload;
+
+	/* Check if the device already has rules configured: we do not support
+	 * rules migration.
+	 */
+	if (macsec_is_configured(macsec))
+		return -EBUSY;
+
+	ops = __macsec_get_ops(offload == MACSEC_OFFLOAD_OFF ? prev_offload : offload,
+			       macsec, &ctx);
+	if (!ops)
+		return -EOPNOTSUPP;
+
+	macsec->offload = offload;
+
+	ctx.secy = &macsec->secy;
+	ret = (offload == MACSEC_OFFLOAD_OFF) ? macsec_offload(ops->mdo_del_secy, &ctx) :
+		      macsec_offload(ops->mdo_add_secy, &ctx);
+
+	if (ret)
+		macsec->offload = prev_offload;
+
+	return ret;
+}
+
 static int macsec_changelink(struct net_device *dev, struct nlattr *tb[],
 			     struct nlattr *data[],
 			     struct netlink_ext_ack *extack)
@@ -3831,6 +3880,12 @@ static int macsec_changelink(struct net_device *dev, struct nlattr *tb[],
 	if (ret)
 		goto cleanup;
 
+	if (data[IFLA_MACSEC_OFFLOAD]) {
+		ret = macsec_changelink_upd_offload(dev, data);
+		if (ret)
+			goto cleanup;
+	}
+
 	/* If h/w offloading is available, propagate to the device */
 	if (macsec_is_offloaded(macsec)) {
 		const struct macsec_ops *ops;
@@ -4231,16 +4286,22 @@ static size_t macsec_get_size(const struct net_device *dev)
 		nla_total_size(1) + /* IFLA_MACSEC_SCB */
 		nla_total_size(1) + /* IFLA_MACSEC_REPLAY_PROTECT */
 		nla_total_size(1) + /* IFLA_MACSEC_VALIDATION */
+		nla_total_size(1) + /* IFLA_MACSEC_OFFLOAD */
 		0;
 }
 
 static int macsec_fill_info(struct sk_buff *skb,
 			    const struct net_device *dev)
 {
-	struct macsec_secy *secy = &macsec_priv(dev)->secy;
-	struct macsec_tx_sc *tx_sc = &secy->tx_sc;
+	struct macsec_tx_sc *tx_sc;
+	struct macsec_dev *macsec;
+	struct macsec_secy *secy;
 	u64 csid;
 
+	macsec = macsec_priv(dev);
+	secy = &macsec->secy;
+	tx_sc = &secy->tx_sc;
+
 	switch (secy->key_len) {
 	case MACSEC_GCM_AES_128_SAK_LEN:
 		csid = secy->xpn ? MACSEC_CIPHER_ID_GCM_AES_XPN_128 : MACSEC_DEFAULT_CIPHER_ID;
@@ -4265,6 +4326,7 @@ static int macsec_fill_info(struct sk_buff *skb,
 	    nla_put_u8(skb, IFLA_MACSEC_SCB, tx_sc->scb) ||
 	    nla_put_u8(skb, IFLA_MACSEC_REPLAY_PROTECT, secy->replay_protect) ||
 	    nla_put_u8(skb, IFLA_MACSEC_VALIDATION, secy->validate_frames) ||
+	    nla_put_u8(skb, IFLA_MACSEC_OFFLOAD, macsec->offload) ||
 	    0)
 		goto nla_put_failure;
 
-- 
2.21.3

Hello,

Quoting ehakim@nvidia.com (2022-12-04 11:06:53)
>  
> +static int macsec_changelink_upd_offload(struct net_device *dev, struct nlattr *data[])
> +{
> +       enum macsec_offload offload, prev_offload;
> +       const struct macsec_ops *ops;
> +       struct macsec_context ctx;
> +       struct macsec_dev *macsec;
> +       int ret = 0;
> +
> +       macsec = macsec_priv(dev);
> +       offload = nla_get_u8(data[IFLA_MACSEC_OFFLOAD]);
> +
> +       /* Check if the offloading mode is supported by the underlying layers */
> +       if (offload != MACSEC_OFFLOAD_OFF &&
> +           !macsec_check_offload(offload, macsec))
> +               return -EOPNOTSUPP;
> +
> +       /* Check if the net device is busy. */
> +       if (netif_running(dev))
> +               return -EBUSY;
> +
> +       if (macsec->offload == offload)
> +               return 0;
> +
> +       prev_offload = macsec->offload;
> +
> +       /* Check if the device already has rules configured: we do not support
> +        * rules migration.
> +        */
> +       if (macsec_is_configured(macsec))
> +               return -EBUSY;
> +
> +       ops = __macsec_get_ops(offload == MACSEC_OFFLOAD_OFF ? prev_offload : offload,
> +                              macsec, &ctx);
> +       if (!ops)
> +               return -EOPNOTSUPP;
> +
> +       macsec->offload = offload;
> +
> +       ctx.secy = &macsec->secy;
> +       ret = (offload == MACSEC_OFFLOAD_OFF) ? macsec_offload(ops->mdo_del_secy, &ctx) :
> +                     macsec_offload(ops->mdo_add_secy, &ctx);
> +
> +       if (ret)
> +               macsec->offload = prev_offload;
> +
> +       return ret;
> +}

The logic above is very close to what is done in macsec_upd_offload,
except for the use of the rtnl lock. You can merge the two in a common
helper and use that to avoid duplication.

Thanks,
Antoine