[PATCH ipsec v4] xfrm: replay: Fix ESN wrap around for GSO

[Christian Langrock <christian.langrock@secunet.com>]

When using GSO it can happen that the wrong seq_hi is used for the last
packets before the wrap around. This can lead to double usage of a
sequence number. To avoid this, we should serialize this last GSO
packet.

Fixes: d7dbefc45cf5 ("xfrm: Add xfrm_replay_overflow functions for...")
Signed-off-by: Christian Langrock <christian.langrock@secunet.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
---
Changes in v4:
 - move changelog within comment
 - add reviewer

Changes in v3:
- fix build
- remove wrapper function

Changes in v2:
- switch to bool as return value
- remove switch case in wrapper function
---
 include/net/xfrm.h     |  1 +
 net/xfrm/xfrm_output.c |  2 +-
 net/xfrm/xfrm_replay.c | 26 ++++++++++++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 6e8fa98f786f..b845f911767c 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1749,6 +1749,7 @@ void xfrm_replay_advance(struct xfrm_state *x, __be32 net_seq);
 int xfrm_replay_check(struct xfrm_state *x, struct sk_buff *skb, __be32 net_seq);
 void xfrm_replay_notify(struct xfrm_state *x, int event);
 int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb);
+bool xfrm_replay_overflow_check(struct xfrm_state *x, struct sk_buff *skb);
 int xfrm_replay_recheck(struct xfrm_state *x, struct sk_buff *skb, __be32 net_seq);
 
 static inline int xfrm_aevent_is_on(struct net *net)
diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index 9a5e79a38c67..c470a68d9c88 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -738,7 +738,7 @@ int xfrm_output(struct sock *sk, struct sk_buff *skb)
 		skb->encapsulation = 1;
 
 		if (skb_is_gso(skb)) {
-			if (skb->inner_protocol)
+			if (skb->inner_protocol || xfrm_replay_overflow_check(x, skb))
 				return xfrm_output_gso(net, sk, skb);
 
 			skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
diff --git a/net/xfrm/xfrm_replay.c b/net/xfrm/xfrm_replay.c
index 9277d81b344c..23858eb5eab4 100644
--- a/net/xfrm/xfrm_replay.c
+++ b/net/xfrm/xfrm_replay.c
@@ -750,6 +750,27 @@ int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb)
 
 	return xfrm_replay_overflow_offload(x, skb);
 }
+
+static bool xfrm_replay_overflow_check(struct xfrm_state *x, struct sk_buff *skb)
+{
+	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
+	__u32 oseq = replay_esn->oseq;
+
+	/* We assume that this function is called with
+	 * skb_is_gso(skb) == true
+	 */
+
+	if (x->repl_mode == XFRM_REPLAY_MODE_ESN) {
+		if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
+			oseq = oseq + 1 + skb_shinfo(skb)->gso_segs;
+			if (unlikely(oseq < replay_esn->oseq))
+				return true;
+		}
+	}
+
+	return false;
+}
+
 #else
 int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb)
 {
@@ -764,6 +785,11 @@ int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb)
 
 	return __xfrm_replay_overflow(x, skb);
 }
+
+bool xfrm_replay_overflow_check(struct xfrm_state *x, struct sk_buff *skb)
+{
+	return false;
+}
 #endif
 
 int xfrm_init_replay(struct xfrm_state *x)
-- 
2.37.1.223.g6a475b71f8