xfrm: delay initialization of offload path till its actually requested

XFRM offload path is probed even if offload isn't needed at all. Let's
make sure that x->type_offload pointer stays NULL for such path to
reduce ambiguity.

Fixes: 9d389d7 ("xfrm: Add a xfrm type offload.")
Signed-off-by: Leon Romanovsky <[email protected]>
Signed-off-by: Steffen Klassert <[email protected]>

Author: rleon

include/net/xfrm.h

@@ -464,6 +464,15 @@ struct xfrm_type_offload {
 
 int xfrm_register_type_offload(const struct xfrm_type_offload *type, unsigned short family);
 void xfrm_unregister_type_offload(const struct xfrm_type_offload *type, unsigned short family);
+void xfrm_set_type_offload(struct xfrm_state *x);
+static inline void xfrm_unset_type_offload(struct xfrm_state *x)
+{
+	if (!x->type_offload)
+		return;
+
+	module_put(x->type_offload->owner);
+	x->type_offload = NULL;
+}
 
 /**
  * struct xfrm_mode_cbs - XFRM mode callbacks
@@ -1760,7 +1769,7 @@ void xfrm_spd_getinfo(struct net *net, struct xfrmk_spdinfo *si);
 u32 xfrm_replay_seqhi(struct xfrm_state *x, __be32 net_seq);
 int xfrm_init_replay(struct xfrm_state *x, struct netlink_ext_ack *extack);
 u32 xfrm_state_mtu(struct xfrm_state *x, int mtu);
-int __xfrm_init_state(struct xfrm_state *x, bool init_replay, bool offload,
+int __xfrm_init_state(struct xfrm_state *x, bool init_replay,
 		      struct netlink_ext_ack *extack);
 int xfrm_init_state(struct xfrm_state *x);
 int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type);

net/xfrm/xfrm_device.c

@@ -244,11 +244,6 @@ int xfrm_dev_state_add(struct net *net, struct xfrm_state *x,
 	xfrm_address_t *daddr;
 	bool is_packet_offload;
 
-	if (!x->type_offload) {
-		NL_SET_ERR_MSG(extack, "Type doesn't support offload");
-		return -EINVAL;
-	}
-
 	if (xuo->flags &
 	    ~(XFRM_OFFLOAD_IPV6 | XFRM_OFFLOAD_INBOUND | XFRM_OFFLOAD_PACKET)) {
 		NL_SET_ERR_MSG(extack, "Unrecognized flags in offload request");
@@ -310,6 +305,13 @@ int xfrm_dev_state_add(struct net *net, struct xfrm_state *x,
 		return -EINVAL;
 	}
 
+	xfrm_set_type_offload(x);
+	if (!x->type_offload) {
+		NL_SET_ERR_MSG(extack, "Type doesn't support offload");
+		dev_put(dev);
+		return -EINVAL;
+	}
+
 	xso->dev = dev;
 	netdev_tracker_alloc(dev, &xso->dev_tracker, GFP_ATOMIC);
 	xso->real_dev = dev;
@@ -332,6 +334,7 @@ int xfrm_dev_state_add(struct net *net, struct xfrm_state *x,
 		netdev_put(dev, &xso->dev_tracker);
 		xso->type = XFRM_DEV_OFFLOAD_UNSPECIFIED;
 
+		xfrm_unset_type_offload(x);
 		/* User explicitly requested packet offload mode and configured
 		 * policy in addition to the XFRM state. So be civil to users,
 		 * and return an error instead of taking fallback path.

net/xfrm/xfrm_state.c

@@ -424,18 +424,18 @@ void xfrm_unregister_type_offload(const struct xfrm_type_offload *type,
 }
 EXPORT_SYMBOL(xfrm_unregister_type_offload);
 
-static const struct xfrm_type_offload *
-xfrm_get_type_offload(u8 proto, unsigned short family, bool try_load)
+void xfrm_set_type_offload(struct xfrm_state *x)
 {
 	const struct xfrm_type_offload *type = NULL;
 	struct xfrm_state_afinfo *afinfo;
+	bool try_load = true;
 
 retry:
-	afinfo = xfrm_state_get_afinfo(family);
+	afinfo = xfrm_state_get_afinfo(x->props.family);
 	if (unlikely(afinfo == NULL))
-		return NULL;
+		goto out;
 
-	switch (proto) {
+	switch (x->id.proto) {
 	case IPPROTO_ESP:
 		type = afinfo->type_offload_esp;
 		break;
@@ -449,18 +449,16 @@ xfrm_get_type_offload(u8 proto, unsigned short family, bool try_load)
 	rcu_read_unlock();
 
 	if (!type && try_load) {
-		request_module("xfrm-offload-%d-%d", family, proto);
+		request_module("xfrm-offload-%d-%d", x->props.family,
+			       x->id.proto);
 		try_load = false;
 		goto retry;
 	}
 
-	return type;
-}
-
-static void xfrm_put_type_offload(const struct xfrm_type_offload *type)
-{
-	module_put(type->owner);
+out:
+	x->type_offload = type;
 }
+EXPORT_SYMBOL(xfrm_set_type_offload);
 
 static const struct xfrm_mode xfrm4_mode_map[XFRM_MODE_MAX] = {
 	[XFRM_MODE_BEET] = {
@@ -609,8 +607,6 @@ static void ___xfrm_state_destroy(struct xfrm_state *x)
 	kfree(x->coaddr);
 	kfree(x->replay_esn);
 	kfree(x->preplay_esn);
-	if (x->type_offload)
-		xfrm_put_type_offload(x->type_offload);
 	if (x->type) {
 		x->type->destructor(x);
 		xfrm_put_type(x->type);
@@ -784,6 +780,8 @@ void xfrm_dev_state_free(struct xfrm_state *x)
 	struct xfrm_dev_offload *xso = &x->xso;
 	struct net_device *dev = READ_ONCE(xso->dev);
 
+	xfrm_unset_type_offload(x);
+
 	if (dev && dev->xfrmdev_ops) {
 		spin_lock_bh(&xfrm_state_dev_gc_lock);
 		if (!hlist_unhashed(&x->dev_gclist))
@@ -3122,7 +3120,7 @@ u32 xfrm_state_mtu(struct xfrm_state *x, int mtu)
 }
 EXPORT_SYMBOL_GPL(xfrm_state_mtu);
 
-int __xfrm_init_state(struct xfrm_state *x, bool init_replay, bool offload,
+int __xfrm_init_state(struct xfrm_state *x, bool init_replay,
 		      struct netlink_ext_ack *extack)
 {
 	const struct xfrm_mode *inner_mode;
@@ -3178,8 +3176,6 @@ int __xfrm_init_state(struct xfrm_state *x, bool init_replay, bool offload,
 		goto error;
 	}
 
-	x->type_offload = xfrm_get_type_offload(x->id.proto, family, offload);
-
 	err = x->type->init_state(x, extack);
 	if (err)
 		goto error;
@@ -3229,7 +3225,7 @@ int xfrm_init_state(struct xfrm_state *x)
 {
 	int err;
 
-	err = __xfrm_init_state(x, true, false, NULL);
+	err = __xfrm_init_state(x, true, NULL);
 	if (!err)
 		x->km.state = XFRM_STATE_VALID;
 

net/xfrm/xfrm_user.c

@@ -919,7 +919,7 @@ static struct xfrm_state *xfrm_state_construct(struct net *net,
 			goto error;
 	}
 
-	err = __xfrm_init_state(x, false, attrs[XFRMA_OFFLOAD_DEV], extack);
+	err = __xfrm_init_state(x, false, extack);
 	if (err)
 		goto error;