xfrm: Fix replay notification for esn.

We may miscalculate the sequence number difference from the
last time we send a notification if a sequence number wrap
occured in the meantime. We fix this by adding a separate
replay notify function for esn. Here we take the high bits
of the sequence number into account to calculate the
difference.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

1 files changed, 67 insertions, 1 deletions

diff --git a/net/xfrm/xfrm_replay.c b/net/xfrm/xfrm_replay.c
index 35754cc8a9e5..a3906737f49e 100644
--- a/net/xfrm/xfrm_replay.c
+++ b/net/xfrm/xfrm_replay.c
@@ -334,6 +334,72 @@ static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
                 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)
+                        break;
+
+                if (replay_esn->seq_hi == preplay_esn->seq_hi)
+                        seq_diff = replay_esn->seq - preplay_esn->seq;
+                else
+                        seq_diff = UINT_MAX - preplay_esn->seq
+                                   + replay_esn->seq;
+
+                if (replay_esn->oseq_hi == preplay_esn->oseq_hi)
+                        oseq_diff = replay_esn->oseq - preplay_esn->oseq;
+                else
+                        oseq_diff = UINT_MAX - preplay_esn->oseq
+                                    + replay_esn->oseq;
+
+                if (seq_diff < x->replay_maxdiff &&
+                    oseq_diff < 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 int xfrm_replay_overflow_esn(struct xfrm_state *x, struct sk_buff *skb)
 {
         int err = 0;
@@ -510,7 +576,7 @@ static 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_bmp,
+        .notify         = xfrm_replay_notify_esn,
         .overflow       = xfrm_replay_overflow_esn,
 };