1 files changed, 754 insertions, 0 deletions

diff --git a/net/xfrm/xfrm_replay.c b/net/xfrm/xfrm_replay.c
new file mode 100644
index 000000000..65d009e3b
--- /dev/null
+++ b/net/xfrm/xfrm_replay.c
@@ -0,0 +1,754 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * xfrm_replay.c - xfrm replay detection, derived from xfrm_state.c.
+ *
+ * Copyright (C) 2010 secunet Security Networks AG
+ * Copyright (C) 2010 Steffen Klassert <steffen.klassert@secunet.com>
+ */
+
+#include <linux/export.h>
+#include <net/xfrm.h>
+
+u32 xfrm_replay_seqhi(struct xfrm_state *x, __be32 net_seq)
+{
+	u32 seq, seq_hi, bottom;
+	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
+
+	if (!(x->props.flags & XFRM_STATE_ESN))
+		return 0;
+
+	seq = ntohl(net_seq);
+	seq_hi = replay_esn->seq_hi;
+	bottom = replay_esn->seq - replay_esn->replay_window + 1;
+
+	if (likely(replay_esn->seq >= replay_esn->replay_window - 1)) {
+		/* A. same subspace */
+		if (unlikely(seq < bottom))
+			seq_hi++;
+	} else {
+		/* B. window spans two subspaces */
+		if (unlikely(seq >= bottom))
+			seq_hi--;
+	}
+
+	return seq_hi;
+}
+EXPORT_SYMBOL(xfrm_replay_seqhi);
+;
+static void xfrm_replay_notify(struct xfrm_state *x, int event)
+{
+	struct km_event c;
+	/* we send notify messages in case
+	 *  1. we updated on of the sequence numbers, and the seqno difference
+	 *     is at least x->replay_maxdiff, in this case we also update the
+	 *     timeout of our timer function
+	 *  2. if x->replay_maxage has elapsed since last update,
+	 *     and there were changes
+	 *
+	 *  The state structure must be locked!
+	 */
+
+	switch (event) {
+	case XFRM_REPLAY_UPDATE:
+		if (!x->replay_maxdiff ||
+		    ((x->replay.seq - x->preplay.seq < x->replay_maxdiff) &&
+		    (x->replay.oseq - x->preplay.oseq < x->replay_maxdiff))) {
+			if (x->xflags & XFRM_TIME_DEFER)
+				event = XFRM_REPLAY_TIMEOUT;
+			else
+				return;
+		}
+
+		break;
+
+	case XFRM_REPLAY_TIMEOUT:
+		if (memcmp(&x->replay, &x->preplay,
+			   sizeof(struct xfrm_replay_state)) == 0) {
+			x->xflags |= XFRM_TIME_DEFER;
+			return;
+		}
+
+		break;
+	}
+
+	memcpy(&x->preplay, &x->replay, sizeof(struct xfrm_replay_state));
+	c.event = XFRM_MSG_NEWAE;
+	c.data.aevent = event;
+	km_state_notify(x, &c);
+
+	if (x->replay_maxage &&
+	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
+		x->xflags &= ~XFRM_TIME_DEFER;
+}
+
+static int xfrm_replay_overflow(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err = 0;
+	struct net *net = xs_net(x);
+
+	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
+		XFRM_SKB_CB(skb)->seq.output.low = ++x->replay.oseq;
+		XFRM_SKB_CB(skb)->seq.output.hi = 0;
+		if (unlikely(x->replay.oseq == 0) &&
+		    !(x->props.extra_flags & XFRM_SA_XFLAG_OSEQ_MAY_WRAP)) {
+			x->replay.oseq--;
+			xfrm_audit_state_replay_overflow(x, skb);
+			err = -EOVERFLOW;
+
+			return err;
+		}
+		if (xfrm_aevent_is_on(net))
+			x->repl->notify(x, XFRM_REPLAY_UPDATE);
+	}
+
+	return err;
+}
+
+static int xfrm_replay_check(struct xfrm_state *x,
+		      struct sk_buff *skb, __be32 net_seq)
+{
+	u32 diff;
+	u32 seq = ntohl(net_seq);
+
+	if (!x->props.replay_window)
+		return 0;
+
+	if (unlikely(seq == 0))
+		goto err;
+
+	if (likely(seq > x->replay.seq))
+		return 0;
+
+	diff = x->replay.seq - seq;
+	if (diff >= x->props.replay_window) {
+		x->stats.replay_window++;
+		goto err;
+	}
+
+	if (x->replay.bitmap & (1U << diff)) {
+		x->stats.replay++;
+		goto err;
+	}
+	return 0;
+
+err:
+	xfrm_audit_state_replay(x, skb, net_seq);
+	return -EINVAL;
+}
+
+static void xfrm_replay_advance(struct xfrm_state *x, __be32 net_seq)
+{
+	u32 diff;
+	u32 seq = ntohl(net_seq);
+
+	if (!x->props.replay_window)
+		return;
+
+	if (seq > x->replay.seq) {
+		diff = seq - x->replay.seq;
+		if (diff < x->props.replay_window)
+			x->replay.bitmap = ((x->replay.bitmap) << diff) | 1;
+		else
+			x->replay.bitmap = 1;
+		x->replay.seq = seq;
+	} else {
+		diff = x->replay.seq - seq;
+		x->replay.bitmap |= (1U << diff);
+	}
+
+	if (xfrm_aevent_is_on(xs_net(x)))
+		x->repl->notify(x, XFRM_REPLAY_UPDATE);
+}
+
+static int xfrm_replay_overflow_bmp(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err = 0;
+	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
+	struct net *net = xs_net(x);
+
+	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
+		XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
+		XFRM_SKB_CB(skb)->seq.output.hi = 0;
+		if (unlikely(replay_esn->oseq == 0) &&
+		    !(x->props.extra_flags & XFRM_SA_XFLAG_OSEQ_MAY_WRAP)) {
+			replay_esn->oseq--;
+			xfrm_audit_state_replay_overflow(x, skb);
+			err = -EOVERFLOW;
+
+			return err;
+		}
+		if (xfrm_aevent_is_on(net))
+			x->repl->notify(x, XFRM_REPLAY_UPDATE);
+	}
+
+	return err;
+}
+
+static int xfrm_replay_check_bmp(struct xfrm_state *x,
+				 struct sk_buff *skb, __be32 net_seq)
+{
+	unsigned int bitnr, nr;
+	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
+	u32 pos;
+	u32 seq = ntohl(net_seq);
+	u32 diff =  replay_esn->seq - seq;
+
+	if (!replay_esn->replay_window)
+		return 0;
+
+	if (unlikely(seq == 0))
+		goto err;
+
+	if (likely(seq > replay_esn->seq))
+		return 0;
+
+	if (diff >= replay_esn->replay_window) {
+		x->stats.replay_window++;
+		goto err;
+	}
+
+	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
+
+	if (pos >= diff)
+		bitnr = (pos - diff) % replay_esn->replay_window;
+	else
+		bitnr = replay_esn->replay_window - (diff - pos);
+
+	nr = bitnr >> 5;
+	bitnr = bitnr & 0x1F;
+	if (replay_esn->bmp[nr] & (1U << bitnr))
+		goto err_replay;
+
+	return 0;
+
+err_replay:
+	x->stats.replay++;
+err:
+	xfrm_audit_state_replay(x, skb, net_seq);
+	return -EINVAL;
+}
+
+static void xfrm_replay_advance_bmp(struct xfrm_state *x, __be32 net_seq)
+{
+	unsigned int bitnr, nr, i;
+	u32 diff;
+	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
+	u32 seq = ntohl(net_seq);
+	u32 pos;
+
+	if (!replay_esn->replay_window)
+		return;
+
+	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
+
+	if (seq > replay_esn->seq) {
+		diff = seq - replay_esn->seq;
+
+		if (diff < replay_esn->replay_window) {
+			for (i = 1; i < diff; i++) {
+				bitnr = (pos + i) % replay_esn->replay_window;
+				nr = bitnr >> 5;
+				bitnr = bitnr & 0x1F;
+				replay_esn->bmp[nr] &=  ~(1U << bitnr);
+			}
+		} else {
+			nr = (replay_esn->replay_window - 1) >> 5;
+			for (i = 0; i <= nr; i++)
+				replay_esn->bmp[i] = 0;
+		}
+
+		bitnr = (pos + diff) % replay_esn->replay_window;
+		replay_esn->seq = seq;
+	} else {
+		diff = replay_esn->seq - seq;
+
+		if (pos >= diff)
+			bitnr = (pos - diff) % replay_esn->replay_window;
+		else
+			bitnr = replay_esn->replay_window - (diff - pos);
+	}
+
+	nr = bitnr >> 5;
+	bitnr = bitnr & 0x1F;
+	replay_esn->bmp[nr] |= (1U << bitnr);
+
+	if (xfrm_aevent_is_on(xs_net(x)))
+		x->repl->notify(x, XFRM_REPLAY_UPDATE);
+}
+
+static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
+{
+	struct km_event c;
+	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
+	struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
+
+	/* we send notify messages in case
+	 *  1. we updated on of the sequence numbers, and the seqno difference
+	 *     is at least x->replay_maxdiff, in this case we also update the
+	 *     timeout of our timer function
+	 *  2. if x->replay_maxage has elapsed since last update,
+	 *     and there were changes
+	 *
+	 *  The state structure must be locked!
+	 */
+
+	switch (event) {
+	case XFRM_REPLAY_UPDATE:
+		if (!x->replay_maxdiff ||
+		    ((replay_esn->seq - preplay_esn->seq < x->replay_maxdiff) &&
+		    (replay_esn->oseq - preplay_esn->oseq
+		     < x->replay_maxdiff))) {
+			if (x->xflags & XFRM_TIME_DEFER)
+				event = XFRM_REPLAY_TIMEOUT;
+			else
+				return;
+		}
+
+		break;
+
+	case XFRM_REPLAY_TIMEOUT:
+		if (memcmp(x->replay_esn, x->preplay_esn,
+			   xfrm_replay_state_esn_len(replay_esn)) == 0) {
+			x->xflags |= XFRM_TIME_DEFER;
+			return;
+		}
+
+		break;
+	}
+
+	memcpy(x->preplay_esn, x->replay_esn,
+	       xfrm_replay_state_esn_len(replay_esn));
+	c.event = XFRM_MSG_NEWAE;
+	c.data.aevent = event;
+	km_state_notify(x, &c);
+
+	if (x->replay_maxage &&
+	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
+		x->xflags &= ~XFRM_TIME_DEFER;
+}
+
+static void xfrm_replay_notify_esn(struct xfrm_state *x, int event)
+{
+	u32 seq_diff, oseq_diff;
+	struct km_event c;
+	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
+	struct xfrm_replay_state_esn *preplay_esn = x->preplay_esn;
+
+	/* we send notify messages in case
+	 *  1. we updated on of the sequence numbers, and the seqno difference
+	 *     is at least x->replay_maxdiff, in this case we also update the
+	 *     timeout of our timer function
+	 *  2. if x->replay_maxage has elapsed since last update,
+	 *     and there were changes
+	 *
+	 *  The state structure must be locked!
+	 */
+
+	switch (event) {
+	case XFRM_REPLAY_UPDATE:
+		if (x->replay_maxdiff) {
+			if (replay_esn->seq_hi == preplay_esn->seq_hi)
+				seq_diff = replay_esn->seq - preplay_esn->seq;
+			else
+				seq_diff = ~preplay_esn->seq + replay_esn->seq
+					   + 1;
+
+			if (replay_esn->oseq_hi == preplay_esn->oseq_hi)
+				oseq_diff = replay_esn->oseq
+					    - preplay_esn->oseq;
+			else
+				oseq_diff = ~preplay_esn->oseq
+					    + replay_esn->oseq + 1;
+
+			if (seq_diff >= x->replay_maxdiff ||
+			    oseq_diff >= x->replay_maxdiff)
+				break;
+		}
+
+		if (x->xflags & XFRM_TIME_DEFER)
+			event = XFRM_REPLAY_TIMEOUT;
+		else
+			return;
+
+		break;
+
+	case XFRM_REPLAY_TIMEOUT:
+		if (memcmp(x->replay_esn, x->preplay_esn,
+			   xfrm_replay_state_esn_len(replay_esn)) == 0) {
+			x->xflags |= XFRM_TIME_DEFER;
+			return;
+		}
+
+		break;
+	}
+
+	memcpy(x->preplay_esn, x->replay_esn,
+	       xfrm_replay_state_esn_len(replay_esn));
+	c.event = XFRM_MSG_NEWAE;
+	c.data.aevent = event;
+	km_state_notify(x, &c);
+
+	if (x->replay_maxage &&
+	    !mod_timer(&x->rtimer, jiffies + x->replay_maxage))
+		x->xflags &= ~XFRM_TIME_DEFER;
+}
+
+static int xfrm_replay_overflow_esn(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err = 0;
+	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
+	struct net *net = xs_net(x);
+
+	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
+		XFRM_SKB_CB(skb)->seq.output.low = ++replay_esn->oseq;
+		XFRM_SKB_CB(skb)->seq.output.hi = replay_esn->oseq_hi;
+
+		if (unlikely(replay_esn->oseq == 0)) {
+			XFRM_SKB_CB(skb)->seq.output.hi = ++replay_esn->oseq_hi;
+
+			if (replay_esn->oseq_hi == 0) {
+				replay_esn->oseq--;
+				replay_esn->oseq_hi--;
+				xfrm_audit_state_replay_overflow(x, skb);
+				err = -EOVERFLOW;
+
+				return err;
+			}
+		}
+		if (xfrm_aevent_is_on(net))
+			x->repl->notify(x, XFRM_REPLAY_UPDATE);
+	}
+
+	return err;
+}
+
+static int xfrm_replay_check_esn(struct xfrm_state *x,
+				 struct sk_buff *skb, __be32 net_seq)
+{
+	unsigned int bitnr, nr;
+	u32 diff;
+	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
+	u32 pos;
+	u32 seq = ntohl(net_seq);
+	u32 wsize = replay_esn->replay_window;
+	u32 top = replay_esn->seq;
+	u32 bottom = top - wsize + 1;
+
+	if (!wsize)
+		return 0;
+
+	if (unlikely(seq == 0 && replay_esn->seq_hi == 0 &&
+		     (replay_esn->seq < replay_esn->replay_window - 1)))
+		goto err;
+
+	diff = top - seq;
+
+	if (likely(top >= wsize - 1)) {
+		/* A. same subspace */
+		if (likely(seq > top) || seq < bottom)
+			return 0;
+	} else {
+		/* B. window spans two subspaces */
+		if (likely(seq > top && seq < bottom))
+			return 0;
+		if (seq >= bottom)
+			diff = ~seq + top + 1;
+	}
+
+	if (diff >= replay_esn->replay_window) {
+		x->stats.replay_window++;
+		goto err;
+	}
+
+	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
+
+	if (pos >= diff)
+		bitnr = (pos - diff) % replay_esn->replay_window;
+	else
+		bitnr = replay_esn->replay_window - (diff - pos);
+
+	nr = bitnr >> 5;
+	bitnr = bitnr & 0x1F;
+	if (replay_esn->bmp[nr] & (1U << bitnr))
+		goto err_replay;
+
+	return 0;
+
+err_replay:
+	x->stats.replay++;
+err:
+	xfrm_audit_state_replay(x, skb, net_seq);
+	return -EINVAL;
+}
+
+static int xfrm_replay_recheck_esn(struct xfrm_state *x,
+				   struct sk_buff *skb, __be32 net_seq)
+{
+	if (unlikely(XFRM_SKB_CB(skb)->seq.input.hi !=
+		     htonl(xfrm_replay_seqhi(x, net_seq)))) {
+			x->stats.replay_window++;
+			return -EINVAL;
+	}
+
+	return xfrm_replay_check_esn(x, skb, net_seq);
+}
+
+static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq)
+{
+	unsigned int bitnr, nr, i;
+	int wrap;
+	u32 diff, pos, seq, seq_hi;
+	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
+
+	if (!replay_esn->replay_window)
+		return;
+
+	seq = ntohl(net_seq);
+	pos = (replay_esn->seq - 1) % replay_esn->replay_window;
+	seq_hi = xfrm_replay_seqhi(x, net_seq);
+	wrap = seq_hi - replay_esn->seq_hi;
+
+	if ((!wrap && seq > replay_esn->seq) || wrap > 0) {
+		if (likely(!wrap))
+			diff = seq - replay_esn->seq;
+		else
+			diff = ~replay_esn->seq + seq + 1;
+
+		if (diff < replay_esn->replay_window) {
+			for (i = 1; i < diff; i++) {
+				bitnr = (pos + i) % replay_esn->replay_window;
+				nr = bitnr >> 5;
+				bitnr = bitnr & 0x1F;
+				replay_esn->bmp[nr] &=  ~(1U << bitnr);
+			}
+		} else {
+			nr = (replay_esn->replay_window - 1) >> 5;
+			for (i = 0; i <= nr; i++)
+				replay_esn->bmp[i] = 0;
+		}
+
+		bitnr = (pos + diff) % replay_esn->replay_window;
+		replay_esn->seq = seq;
+
+		if (unlikely(wrap > 0))
+			replay_esn->seq_hi++;
+	} else {
+		diff = replay_esn->seq - seq;
+
+		if (pos >= diff)
+			bitnr = (pos - diff) % replay_esn->replay_window;
+		else
+			bitnr = replay_esn->replay_window - (diff - pos);
+	}
+
+	xfrm_dev_state_advance_esn(x);
+
+	nr = bitnr >> 5;
+	bitnr = bitnr & 0x1F;
+	replay_esn->bmp[nr] |= (1U << bitnr);
+
+	if (xfrm_aevent_is_on(xs_net(x)))
+		x->repl->notify(x, XFRM_REPLAY_UPDATE);
+}
+
+#ifdef CONFIG_XFRM_OFFLOAD
+static int xfrm_replay_overflow_offload(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err = 0;
+	struct net *net = xs_net(x);
+	struct xfrm_offload *xo = xfrm_offload(skb);
+	__u32 oseq = x->replay.oseq;
+
+	if (!xo)
+		return xfrm_replay_overflow(x, skb);
+
+	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
+		if (!skb_is_gso(skb)) {
+			XFRM_SKB_CB(skb)->seq.output.low = ++oseq;
+			xo->seq.low = oseq;
+		} else {
+			XFRM_SKB_CB(skb)->seq.output.low = oseq + 1;
+			xo->seq.low = oseq + 1;
+			oseq += skb_shinfo(skb)->gso_segs;
+		}
+
+		XFRM_SKB_CB(skb)->seq.output.hi = 0;
+		xo->seq.hi = 0;
+		if (unlikely(oseq < x->replay.oseq) &&
+		    !(x->props.extra_flags & XFRM_SA_XFLAG_OSEQ_MAY_WRAP)) {
+			xfrm_audit_state_replay_overflow(x, skb);
+			err = -EOVERFLOW;
+
+			return err;
+		}
+
+		x->replay.oseq = oseq;
+
+		if (xfrm_aevent_is_on(net))
+			x->repl->notify(x, XFRM_REPLAY_UPDATE);
+	}
+
+	return err;
+}
+
+static int xfrm_replay_overflow_offload_bmp(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err = 0;
+	struct xfrm_offload *xo = xfrm_offload(skb);
+	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
+	struct net *net = xs_net(x);
+	__u32 oseq = replay_esn->oseq;
+
+	if (!xo)
+		return xfrm_replay_overflow_bmp(x, skb);
+
+	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
+		if (!skb_is_gso(skb)) {
+			XFRM_SKB_CB(skb)->seq.output.low = ++oseq;
+			xo->seq.low = oseq;
+		} else {
+			XFRM_SKB_CB(skb)->seq.output.low = oseq + 1;
+			xo->seq.low = oseq + 1;
+			oseq += skb_shinfo(skb)->gso_segs;
+		}
+
+		XFRM_SKB_CB(skb)->seq.output.hi = 0;
+		xo->seq.hi = 0;
+		if (unlikely(oseq < replay_esn->oseq) &&
+		    !(x->props.extra_flags & XFRM_SA_XFLAG_OSEQ_MAY_WRAP)) {
+			xfrm_audit_state_replay_overflow(x, skb);
+			err = -EOVERFLOW;
+
+			return err;
+		} else {
+			replay_esn->oseq = oseq;
+		}
+
+		if (xfrm_aevent_is_on(net))
+			x->repl->notify(x, XFRM_REPLAY_UPDATE);
+	}
+
+	return err;
+}
+
+static int xfrm_replay_overflow_offload_esn(struct xfrm_state *x, struct sk_buff *skb)
+{
+	int err = 0;
+	struct xfrm_offload *xo = xfrm_offload(skb);
+	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
+	struct net *net = xs_net(x);
+	__u32 oseq = replay_esn->oseq;
+	__u32 oseq_hi = replay_esn->oseq_hi;
+
+	if (!xo)
+		return xfrm_replay_overflow_esn(x, skb);
+
+	if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
+		if (!skb_is_gso(skb)) {
+			XFRM_SKB_CB(skb)->seq.output.low = ++oseq;
+			XFRM_SKB_CB(skb)->seq.output.hi = oseq_hi;
+			xo->seq.low = oseq;
+			xo->seq.hi = oseq_hi;
+		} else {
+			XFRM_SKB_CB(skb)->seq.output.low = oseq + 1;
+			XFRM_SKB_CB(skb)->seq.output.hi = oseq_hi;
+			xo->seq.low = oseq + 1;
+			xo->seq.hi = oseq_hi;
+			oseq += skb_shinfo(skb)->gso_segs;
+		}
+
+		if (unlikely(xo->seq.low < replay_esn->oseq)) {
+			XFRM_SKB_CB(skb)->seq.output.hi = ++oseq_hi;
+			xo->seq.hi = oseq_hi;
+			replay_esn->oseq_hi = oseq_hi;
+			if (replay_esn->oseq_hi == 0) {
+				replay_esn->oseq--;
+				replay_esn->oseq_hi--;
+				xfrm_audit_state_replay_overflow(x, skb);
+				err = -EOVERFLOW;
+
+				return err;
+			}
+		}
+
+		replay_esn->oseq = oseq;
+
+		if (xfrm_aevent_is_on(net))
+			x->repl->notify(x, XFRM_REPLAY_UPDATE);
+	}
+
+	return err;
+}
+
+static const struct xfrm_replay xfrm_replay_legacy = {
+	.advance	= xfrm_replay_advance,
+	.check		= xfrm_replay_check,
+	.recheck	= xfrm_replay_check,
+	.notify		= xfrm_replay_notify,
+	.overflow	= xfrm_replay_overflow_offload,
+};
+
+static const struct xfrm_replay xfrm_replay_bmp = {
+	.advance	= xfrm_replay_advance_bmp,
+	.check		= xfrm_replay_check_bmp,
+	.recheck	= xfrm_replay_check_bmp,
+	.notify		= xfrm_replay_notify_bmp,
+	.overflow	= xfrm_replay_overflow_offload_bmp,
+};
+
+static const struct xfrm_replay xfrm_replay_esn = {
+	.advance	= xfrm_replay_advance_esn,
+	.check		= xfrm_replay_check_esn,
+	.recheck	= xfrm_replay_recheck_esn,
+	.notify		= xfrm_replay_notify_esn,
+	.overflow	= xfrm_replay_overflow_offload_esn,
+};
+#else
+static const struct xfrm_replay xfrm_replay_legacy = {
+	.advance	= xfrm_replay_advance,
+	.check		= xfrm_replay_check,
+	.recheck	= xfrm_replay_check,
+	.notify		= xfrm_replay_notify,
+	.overflow	= xfrm_replay_overflow,
+};
+
+static const struct xfrm_replay xfrm_replay_bmp = {
+	.advance	= xfrm_replay_advance_bmp,
+	.check		= xfrm_replay_check_bmp,
+	.recheck	= xfrm_replay_check_bmp,
+	.notify		= xfrm_replay_notify_bmp,
+	.overflow	= xfrm_replay_overflow_bmp,
+};
+
+static const struct xfrm_replay xfrm_replay_esn = {
+	.advance	= xfrm_replay_advance_esn,
+	.check		= xfrm_replay_check_esn,
+	.recheck	= xfrm_replay_recheck_esn,
+	.notify		= xfrm_replay_notify_esn,
+	.overflow	= xfrm_replay_overflow_esn,
+};
+#endif
+
+int xfrm_init_replay(struct xfrm_state *x)
+{
+	struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
+
+	if (replay_esn) {
+		if (replay_esn->replay_window >
+		    replay_esn->bmp_len * sizeof(__u32) * 8)
+			return -EINVAL;
+
+		if (x->props.flags & XFRM_STATE_ESN) {
+			if (replay_esn->replay_window == 0)
+				return -EINVAL;
+			x->repl = &xfrm_replay_esn;
+		} else {
+			x->repl = &xfrm_replay_bmp;
+		}
+	} else {
+		x->repl = &xfrm_replay_legacy;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(xfrm_init_replay);