xfrm: Flushing empty SPD generates false events

To see the effect make sure you have an empty SPD.
On window1 "ip xfrm mon" and on window2 issue "ip xfrm policy flush"
You get prompt back in window2 and you see the flush event on window1.
With this fix, you still get prompt on window1 but no event on window2.

Thanks to Alexey Dobriyan for finding a bug in earlier version
when using pfkey to do the flushing.

Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 20 insertions, 6 deletions

diff --git a/net/key/af_key.c b/net/key/af_key.c
index c269ce6094d6..a20d2fa88db9 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -2735,8 +2735,11 @@ static int pfkey_spdflush(struct sock *sk, struct sk_buff *skb, struct sadb_msg
         audit_info.secid = 0;
         err = xfrm_policy_flush(net, XFRM_POLICY_TYPE_MAIN, &audit_info);
         err2 = unicast_flush_resp(sk, hdr);
-        if (err || err2)
-                return err ? err : err2;
+        if (err || err2) {
+                if (err == -ESRCH) /* empty table - old silent behavior */
+                        return 0;
+                return err;
+        }
 
         c.data.type = XFRM_POLICY_TYPE_MAIN;
         c.event = XFRM_MSG_FLUSHPOLICY;
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 4368e7b88469..d6eb16d75243 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -771,7 +771,8 @@ xfrm_policy_flush_secctx_check(struct net *net, u8 type, struct xfrm_audit *audi
 
 int xfrm_policy_flush(struct net *net, u8 type, struct xfrm_audit *audit_info)
 {
-        int dir, err = 0;
+        int dir, err = 0, cnt = 0;
+        struct xfrm_policy *dp;
 
         write_lock_bh(&xfrm_policy_lock);
 
@@ -789,8 +790,10 @@ int xfrm_policy_flush(struct net *net, u8 type, struct xfrm_audit *audit_info)
                                      &net->xfrm.policy_inexact[dir], bydst) {
                         if (pol->type != type)
                                 continue;
-                        __xfrm_policy_unlink(pol, dir);
+                        dp = __xfrm_policy_unlink(pol, dir);
                         write_unlock_bh(&xfrm_policy_lock);
+                        if (dp)
+                                cnt++;
 
                         xfrm_audit_policy_delete(pol, 1, audit_info->loginuid,
                                                  audit_info->sessionid,
@@ -809,8 +812,10 @@ int xfrm_policy_flush(struct net *net, u8 type, struct xfrm_audit *audit_info)
                                              bydst) {
                                 if (pol->type != type)
                                         continue;
-                                __xfrm_policy_unlink(pol, dir);
+                                dp = __xfrm_policy_unlink(pol, dir);
                                 write_unlock_bh(&xfrm_policy_lock);
+                                if (dp)
+                                        cnt++;
 
                                 xfrm_audit_policy_delete(pol, 1,
                                                          audit_info->loginuid,
@@ -824,6 +829,8 @@ int xfrm_policy_flush(struct net *net, u8 type, struct xfrm_audit *audit_info)
                 }
 
         }
+        if (!cnt)
+                err = -ESRCH;
         atomic_inc(&flow_cache_genid);
 out:
         write_unlock_bh(&xfrm_policy_lock);
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index cd94a9dd1bad..ee04e6bf0e54 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1679,8 +1679,12 @@ static int xfrm_flush_policy(struct sk_buff *skb, struct nlmsghdr *nlh,
         audit_info.sessionid = NETLINK_CB(skb).sessionid;
         audit_info.secid = NETLINK_CB(skb).sid;
         err = xfrm_policy_flush(net, type, &audit_info);
-        if (err)
+        if (err) {
+                if (err == -ESRCH) /* empty table */
+                        return 0;
                 return err;
+        }
+
         c.data.type = type;
         c.event = nlh->nlmsg_type;
         c.seq = nlh->nlmsg_seq;