xfrm: rate limit SA mapping change message to user space

Kernel generates mapping change message, XFRM_MSG_MAPPING,
when a source port chage is detected on a input state with UDP
encapsulation set.  Kernel generates a message for each IPsec packet
with new source port.  For a high speed flow per packet mapping change
message can be excessive, and can overload the user space listener.

Introduce rate limiting for XFRM_MSG_MAPPING message to the user space.

The rate limiting is configurable via netlink, when adding a new SA or
updating it. Use the new attribute XFRMA_MTIMER_THRESH in seconds.

v1->v2 change:
	update xfrm_sa_len()

v2->v3 changes:
	use u32 insted unsigned long to reduce size of struct xfrm_state
	fix xfrm_ompat size Reported-by: kernel test robot <lkp@intel.com>
	accept XFRM_MSG_MAPPING only when XFRMA_ENCAP is present

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

1 files changed, 22 insertions, 1 deletions

diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index a2f4001221d1..78d51399a0f4 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -1593,6 +1593,9 @@ static struct xfrm_state *xfrm_state_clone(struct xfrm_state *orig,
 	x->km.seq = orig->km.seq;
 	x->replay = orig->replay;
 	x->preplay = orig->preplay;
+	x->mapping_maxage = orig->mapping_maxage;
+	x->new_mapping = 0;
+	x->new_mapping_sport = 0;
 
 	return x;
 
@@ -2242,7 +2245,7 @@ int km_query(struct xfrm_state *x, struct xfrm_tmpl *t, struct xfrm_policy *pol)
 }
 EXPORT_SYMBOL(km_query);
 
-int km_new_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr, __be16 sport)
+static int __km_new_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr, __be16 sport)
 {
 	int err = -EINVAL;
 	struct xfrm_mgr *km;
@@ -2257,6 +2260,24 @@ int km_new_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr, __be16 sport)
 	rcu_read_unlock();
 	return err;
 }
+
+int km_new_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr, __be16 sport)
+{
+	int ret = 0;
+
+	if (x->mapping_maxage) {
+		if ((jiffies / HZ - x->new_mapping) > x->mapping_maxage ||
+		    x->new_mapping_sport != sport) {
+			x->new_mapping_sport = sport;
+			x->new_mapping = jiffies / HZ;
+			ret = __km_new_mapping(x, ipaddr, sport);
+		}
+	} else {
+		ret = __km_new_mapping(x, ipaddr, sport);
+	}
+
+	return ret;
+}
 EXPORT_SYMBOL(km_new_mapping);
 
 void km_policy_expired(struct xfrm_policy *pol, int dir, int hard, u32 portid)