xfrm: Add SA to hardware at the end of xfrm_state_construct()

Current code configures the hardware with a new SA before the state has been
fully initialized. During this time interval, an incoming ESP packet can cause
a crash due to a NULL dereference. More specifically, xfrm_input() considers
the packet as valid, and yet, anti-replay mechanism is not initialized.

Move hardware configuration to the end of xfrm_state_construct(), and mark
the state as valid once the SA is fully initialized.

Fixes: d77e38e ("xfrm: Add an IPsec hardware offloading API")
Signed-off-by: Aviad Yehezkel <[email protected]>
Signed-off-by: Aviv Heller <[email protected]>
Signed-off-by: Yossi Kuperman <[email protected]>
Signed-off-by: Steffen Klassert <[email protected]>

Author: Yossi Kuperman

net/xfrm/xfrm_state.c

@@ -2272,8 +2272,6 @@ int __xfrm_init_state(struct xfrm_state *x, bool init_replay, bool offload)
 			goto error;
 	}
 
-	x->km.state = XFRM_STATE_VALID;
-
 error:
 	return err;
 }
@@ -2282,7 +2280,13 @@ EXPORT_SYMBOL(__xfrm_init_state);
 
 int xfrm_init_state(struct xfrm_state *x)
 {
-	return __xfrm_init_state(x, true, false);
+	int err;
+
+	err = __xfrm_init_state(x, true, false);
+	if (!err)
+		x->km.state = XFRM_STATE_VALID;
+
+	return err;
 }
 
 EXPORT_SYMBOL(xfrm_init_state);

net/xfrm/xfrm_user.c

@@ -598,13 +598,6 @@ static struct xfrm_state *xfrm_state_construct(struct net *net,
 			goto error;
 	}
 
-	if (attrs[XFRMA_OFFLOAD_DEV]) {
-		err = xfrm_dev_state_add(net, x,
-					 nla_data(attrs[XFRMA_OFFLOAD_DEV]));
-		if (err)
-			goto error;
-	}
-
 	if ((err = xfrm_alloc_replay_state_esn(&x->replay_esn, &x->preplay_esn,
 					       attrs[XFRMA_REPLAY_ESN_VAL])))
 		goto error;
@@ -620,6 +613,14 @@ static struct xfrm_state *xfrm_state_construct(struct net *net,
 	/* override default values from above */
 	xfrm_update_ae_params(x, attrs, 0);
 
+	/* configure the hardware if offload is requested */
+	if (attrs[XFRMA_OFFLOAD_DEV]) {
+		err = xfrm_dev_state_add(net, x,
+					 nla_data(attrs[XFRMA_OFFLOAD_DEV]));
+		if (err)
+			goto error;
+	}
+
 	return x;
 
 error:
@@ -662,6 +663,9 @@ static int xfrm_add_sa(struct sk_buff *skb, struct nlmsghdr *nlh,
 		goto out;
 	}
 
+	if (x->km.state == XFRM_STATE_VOID)
+		x->km.state = XFRM_STATE_VALID;
+
 	c.seq = nlh->nlmsg_seq;
 	c.portid = nlh->nlmsg_pid;
 	c.event = nlh->nlmsg_type;