xfrm: Fix aevent generation for each received packet

If asynchronous events are enabled for a particular netlink socket,
the notify function is called by the advance function. The notify
function creates and dispatches a km_event if a replay timeout occurred,
or at least replay_maxdiff packets have been received since the last
asynchronous event has been sent. The function is supposed to return if
neither of the two events were detected for a state, or replay_maxdiff
is equal to zero.
Replay_maxdiff is initialized in xfrm_state_construct to the value of
the xfrm.sysctl_aevent_rseqth (2 by default), and updated if for a state
if the netlink attribute XFRMA_REPLAY_THRESH is set.
If, however, replay_maxdiff is set to zero, then all of the three notify
implementations perform a break from the switch statement instead of
checking whether a timeout occurred, and -- if not -- return.  As a
result an asynchronous event is generated for every replay update of a
state that has a zero replay_maxdiff value.
This patch modifies the notify functions such that they immediately
return if replay_maxdiff has the value zero, unless a timeout occurred.

Signed-off-by: Thomas Egerer <thomas.egerer@secunet.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

1 files changed, 27 insertions, 24 deletions

diff --git a/net/xfrm/xfrm_replay.c b/net/xfrm/xfrm_replay.c
index eeca388effc7..dab57daae408 100644
--- a/net/xfrm/xfrm_replay.c
+++ b/net/xfrm/xfrm_replay.c
@@ -61,9 +61,9 @@ static void xfrm_replay_notify(struct xfrm_state *x, int event)
 
         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->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
@@ -301,9 +301,10 @@ static void xfrm_replay_notify_bmp(struct xfrm_state *x, int event)
 
         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->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
@@ -352,28 +353,30 @@ static void xfrm_replay_notify_esn(struct xfrm_state *x, int event)
 
         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 = ~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) {
+                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 (x->xflags & XFRM_TIME_DEFER)
-                                event = XFRM_REPLAY_TIMEOUT;
+                        if (replay_esn->oseq_hi == preplay_esn->oseq_hi)
+                                oseq_diff = replay_esn->oseq
+                                            - preplay_esn->oseq;
                         else
-                                return;
+                                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: