This patch adds support for IPsec extended sequence numbers (esn)
as defined in RFC 4303. The bits to manage the anti-replay window
are based on a patch from Alex Badea.
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
---
include/net/xfrm.h | 1 +
net/xfrm/xfrm_input.c | 4 +
net/xfrm/xfrm_replay.c | 190 +++++++++++++++++++++++++++++++++++++++++++++++-
3 files changed, 194 insertions(+), 1 deletions(-)
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 4b1559a..a6ef001 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1412,6 +1412,7 @@ extern int xfrm_state_delete(struct xfrm_state *x);
extern int xfrm_state_flush(struct net *net, u8 proto, struct xfrm_audit *audit_info);
extern void xfrm_sad_getinfo(struct net *net, struct xfrmk_sadinfo *si);
extern void xfrm_spd_getinfo(struct net *net, struct xfrmk_spdinfo *si);
+extern u32 xfrm_replay_seqhi(struct xfrm_state *x, __be32 net_seq);
extern int xfrm_init_replay(struct xfrm_state *x);
extern int xfrm_state_mtu(struct xfrm_state *x, int mtu);
extern int xfrm_init_state(struct xfrm_state *x);
diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 55d5f5c..872065c 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -107,6 +107,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
struct net *net = dev_net(skb->dev);
int err;
__be32 seq;
+ __be32 seq_hi;
struct xfrm_state *x;
xfrm_address_t *daddr;
struct xfrm_mode *inner_mode;
@@ -184,7 +185,10 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type)
spin_unlock(&x->lock);
+ seq_hi = htonl(xfrm_replay_seqhi(x, seq));
+
XFRM_SKB_CB(skb)->seq.input.low = seq;
+ XFRM_SKB_CB(skb)->seq.input.hi = seq_hi;
nexthdr = x->type->input(x, skb);
diff --git a/net/xfrm/xfrm_replay.c b/net/xfrm/xfrm_replay.c
index be2c9eb..52433b5 100644
--- a/net/xfrm/xfrm_replay.c
+++ b/net/xfrm/xfrm_replay.c
@@ -20,6 +20,31 @@
#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;
+}
+
static void xfrm_replay_notify(struct xfrm_state *x, int event)
{
struct km_event c;
@@ -313,6 +338,160 @@ static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
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 seq = ntohl(net_seq);
+ u32 pos = (replay_esn->seq - 1) % replay_esn->replay_window;
+ u32 wsize = replay_esn->replay_window;
+ u32 top = replay_esn->seq;
+ u32 bottom = top - wsize + 1;
+
+ 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;
+ }
+
+ if (pos >= diff) {
+ bitnr = (pos - diff) % replay_esn->replay_window;
+ nr = bitnr >> 5;
+ bitnr = bitnr & 0x1F;
+ if (replay_esn->bmp[nr] & (1U << bitnr))
+ goto err_replay;
+ } 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_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);
+ }
+
+ bitnr = (pos + diff) % replay_esn->replay_window;
+ nr = bitnr >> 5;
+ bitnr = bitnr & 0x1F;
+ replay_esn->bmp[nr] |= (1U << bitnr);
+ } else {
+ nr = replay_esn->replay_window >> 5;
+ for (i = 0; i <= nr; i++)
+ replay_esn->bmp[i] = 0;
+
+ bitnr = (pos + diff) % replay_esn->replay_window;
+ nr = bitnr >> 5;
+ bitnr = bitnr & 0x1F;
+ replay_esn->bmp[nr] |= (1U << bitnr);
+ }
+
+ 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;
+ nr = bitnr >> 5;
+ bitnr = bitnr & 0x1F;
+ replay_esn->bmp[nr] |= (1U << bitnr);
+ } 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)))
+ xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
+}
+
static struct xfrm_replay xfrm_replay_legacy = {
.advance = xfrm_replay_advance,
.check = xfrm_replay_check,
@@ -327,9 +506,18 @@ static struct xfrm_replay xfrm_replay_bmp = {
.overflow = xfrm_replay_overflow_bmp,
};
+static struct xfrm_replay xfrm_replay_esn = {
+ .advance = xfrm_replay_advance_esn,
+ .check = xfrm_replay_check_esn,
+ .notify = xfrm_replay_notify_bmp,
+ .overflow = xfrm_replay_overflow_esn,
+};
+
int xfrm_init_replay(struct xfrm_state *x)
{
- if (x->replay_esn)
+ if ((x->props.flags & XFRM_STATE_ESN) && x->replay_esn)
+ x->repl = &xfrm_replay_esn;
+ else if (x->replay_esn)
x->repl = &xfrm_replay_bmp;
else
x->repl = &xfrm_replay_legacy;
--
1.7.0.4
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