Re: [PATCH net-ipsec v2] xfrm: replay: Fix ESN wrap around for GSO

Leon Romanovsky
2022-09-28T06:18:18Z

On Tue, Sep 27, 2022 at 02:59:50PM +0200, Christian Langrock wrote:
> 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>
> ---
> include/net/xfrm.h | 1 +
> net/xfrm/xfrm_output.c | 2 +-
> net/xfrm/xfrm_replay.c | 33 +++++++++++++++++++++++++++++++++
> 3 files changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/include/net/xfrm.h b/include/net/xfrm.h
> index 6e8fa98f786f..49d6d974f493 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);
> +int 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..991cfc7a091d 100644
> --- a/net/xfrm/xfrm_replay.c
> +++ b/net/xfrm/xfrm_replay.c
> @@ -750,6 +750,34 @@ 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_offload_esn(struct xfrm_state *x, struct sk_buff *skb)
> +{
> + struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
> + __u32 oseq = replay_esn->oseq;
> + bool ret = false;
> +
> + /* We assume that this function is called with
> + * skb_is_gso(skb) == true
> + */
> +
> + if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
> + oseq = oseq + 1 + skb_shinfo(skb)->gso_segs;
> + if (unlikely(oseq < replay_esn->oseq))
> + ret = true;

return true;

> + }
> +
> + return ret;

return false;

> +}
> +
> +bool xfrm_replay_overflow_check(struct xfrm_state *x, struct sk_buff *skb)
> +{
> + if (x->repl_mode == XFRM_REPLAY_MODE_ESN)
> + return xfrm_replay_overflow_check_offload_esn(x, skb);
> +
> + return false;
> +}

I still think that functions above should be merged into one. This is
called only if xfrm_dev_offload_ok() success -> in crypto offload path.

Thanks

> +
> #else
> int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb)
> {
> @@ -764,6 +792,11 @@ int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb)
>
> return __xfrm_replay_overflow(x, skb);
> }
> +
> +int xfrm_replay_overflow_check(struct xfrm_state *x, struct sk_buff *skb)

int -> bool

> +{
> + return 0;
> +}
> #endif
>
> int xfrm_init_replay(struct xfrm_state *x)
> --
> 2.37.1.223.g6a475b71f8
>