[XFRM]: Add generation count to xfrm_state and xfrm_dst.

Each xfrm_state inserted gets a new generation counter
value.  When a bundle is created, the xfrm_dst objects
get the current generation counter of the xfrm_state
they will attach to at dst->xfrm.

xfrm_bundle_ok() will return false if it sees an
xfrm_dst with a generation count different from the
generation count of the xfrm_state that dst points to.

This provides a facility by which to passively and
cheaply invalidate cached IPSEC routes during SA
database changes.

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 5 insertions, 0 deletions

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 1732159ffd01..7fc6944ee36f 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1536,6 +1536,8 @@ int xfrm_bundle_ok(struct xfrm_dst *first, struct flowi *fl, int family, int str
                         return 0;
                 if (dst->xfrm->km.state != XFRM_STATE_VALID)
                         return 0;
+                if (xdst->genid != dst->xfrm->genid)
+                        return 0;
 
                 if (strict && fl && dst->xfrm->props.mode != XFRM_MODE_TUNNEL &&
                     !xfrm_state_addr_flow_check(dst->xfrm, fl, family))
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 445263c54c94..535d43c14720 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -53,6 +53,7 @@ static struct hlist_head *xfrm_state_byspi __read_mostly;
 static unsigned int xfrm_state_hmask __read_mostly;
 static unsigned int xfrm_state_hashmax __read_mostly = 1 * 1024 * 1024;
 static unsigned int xfrm_state_num;
+static unsigned int xfrm_state_genid;
 
 static inline unsigned int __xfrm4_dst_hash(xfrm_address_t *addr, unsigned int hmask)
 {
@@ -745,6 +746,8 @@ static void __xfrm_state_insert(struct xfrm_state *x)
 {
         unsigned int h = xfrm_dst_hash(&x->id.daddr, x->props.family);
 
+        x->genid = ++xfrm_state_genid;
+
         hlist_add_head(&x->bydst, xfrm_state_bydst+h);
         xfrm_state_hold(x);