[PATCH ipsec-next 07/11] xfrm: policy: add inexact policy search tree infrastructure

[Florian Westphal <fw@strlen.de>]

At this time inexact policies are all searched in-order until the first
match is found.  After removal of the flow cache, this resolution has
to be performed for every packetm resulting in major slowdown when
number of inexact policies is high.

This adds infrastructure to later sort inexact policies into a tree.
This only introduces a single class: any:any.

Next patch will add a search tree to pre-sort policies that
have a fixed daddr/prefixlen, so in this patch the any:any class
will still be used for all policies.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 include/net/xfrm.h     |   1 +
 net/xfrm/xfrm_policy.c | 301 +++++++++++++++++++++++++++++++++--------
 2 files changed, 248 insertions(+), 54 deletions(-)

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 870fa9b27f7e..9df6dca17155 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -577,6 +577,7 @@ struct xfrm_policy {
 	/* This lock only affects elements except for entry. */
 	rwlock_t		lock;
 	refcount_t		refcnt;
+	u32			pos;
 	struct timer_list	timer;
 
 	atomic_t		genid;
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index dda27fd7b8a4..4eb12e9b40c2 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -46,6 +46,9 @@ struct xfrm_flo {
 	u8 flags;
 };
 
+/* prefixes smaller than this are stored in lists, not trees. */
+#define INEXACT_PREFIXLEN_IPV4	16
+#define INEXACT_PREFIXLEN_IPV6	48
 struct xfrm_pol_inexact_key {
 	possible_net_t net;
 	u32 if_id;
@@ -56,6 +59,7 @@ struct xfrm_pol_inexact_key {
 struct xfrm_pol_inexact_bin {
 	struct xfrm_pol_inexact_key k;
 	struct rhash_head head;
+	/* list containing '*:*' policies */
 	struct hlist_head hhead;
 
 	/* slow path below */
@@ -63,6 +67,16 @@ struct xfrm_pol_inexact_bin {
 	struct rcu_head rcu;
 };
 
+enum xfrm_pol_inexact_candidate_type {
+	XFRM_POL_CAND_ANY,
+
+	XFRM_POL_CAND_MAX,
+};
+
+struct xfrm_pol_inexact_candidates {
+	struct hlist_head *res[XFRM_POL_CAND_MAX];
+};
+
 static DEFINE_SPINLOCK(xfrm_if_cb_lock);
 static struct xfrm_if_cb const __rcu *xfrm_if_cb __read_mostly;
 
@@ -98,6 +112,12 @@ xfrm_policy_insert_list(struct hlist_head *chain, struct xfrm_policy *policy,
 static void xfrm_policy_insert_inexact_list(struct hlist_head *chain,
 					    struct xfrm_policy *policy);
 
+static bool
+xfrm_policy_find_inexact_candidates(struct xfrm_pol_inexact_candidates *cand,
+				    struct xfrm_pol_inexact_bin *b,
+				    const xfrm_address_t *saddr,
+				    const xfrm_address_t *daddr);
+
 static inline bool xfrm_pol_hold_rcu(struct xfrm_policy *policy)
 {
 	return refcount_inc_not_zero(&policy->refcnt);
@@ -652,13 +672,48 @@ xfrm_policy_inexact_alloc_bin(const struct xfrm_policy *pol, u8 dir)
 	return IS_ERR(prev) ? NULL : prev;
 }
 
-static void xfrm_policy_inexact_delete_bin(struct net *net,
-					   struct xfrm_pol_inexact_bin *b)
+static bool xfrm_pol_inexact_addr_use_any_list(const xfrm_address_t *addr,
+					       int family, u8 prefixlen)
 {
-	lockdep_assert_held(&net->xfrm.xfrm_policy_lock);
+	if (xfrm_addr_any(addr, family))
+		return true;
+
+	if (family == AF_INET6 && prefixlen < INEXACT_PREFIXLEN_IPV6)
+		return true;
+
+	if (family == AF_INET && prefixlen < INEXACT_PREFIXLEN_IPV4)
+		return true;
+
+	return false;
+}
+
+static bool
+xfrm_policy_inexact_insert_use_any_list(const struct xfrm_policy *policy)
+{
+	const xfrm_address_t *addr;
+	bool saddr_any, daddr_any;
+	u8 prefixlen;
+
+	addr = &policy->selector.saddr;
+	prefixlen = policy->selector.prefixlen_s;
 
-	if (!hlist_empty(&b->hhead))
+	saddr_any = xfrm_pol_inexact_addr_use_any_list(addr,
+						       policy->family,
+						       prefixlen);
+	addr = &policy->selector.daddr;
+	prefixlen = policy->selector.prefixlen_d;
+	daddr_any = xfrm_pol_inexact_addr_use_any_list(addr,
+						       policy->family,
+						       prefixlen);
+	return saddr_any && daddr_any;
+}
+
+static void __xfrm_policy_inexact_prune_bin(struct xfrm_pol_inexact_bin *b, bool net_exit)
+{
+	if (!hlist_empty(&b->hhead)) {
+		WARN_ON_ONCE(net_exit);
 		return;
+	}
 
 	if (rhashtable_remove_fast(&xfrm_policy_inexact_table, &b->head,
 				   xfrm_pol_inexact_params) == 0) {
@@ -667,14 +722,23 @@ static void xfrm_policy_inexact_delete_bin(struct net *net,
 	}
 }
 
+static void xfrm_policy_inexact_prune_bin(struct xfrm_pol_inexact_bin *b)
+{
+	struct net *net = read_pnet(&b->k.net);
+
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
+	__xfrm_policy_inexact_prune_bin(b, false);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
+}
+
 static void __xfrm_policy_inexact_flush(struct net *net)
 {
-	struct xfrm_pol_inexact_bin *bin;
+	struct xfrm_pol_inexact_bin *bin, *t;
 
 	lockdep_assert_held(&net->xfrm.xfrm_policy_lock);
 
-	list_for_each_entry(bin, &net->xfrm.inexact_bins, inexact_bins)
-		xfrm_policy_inexact_delete_bin(net, bin);
+	list_for_each_entry_safe(bin, t, &net->xfrm.inexact_bins, inexact_bins)
+		__xfrm_policy_inexact_prune_bin(bin, false);
 }
 
 static struct xfrm_policy *
@@ -689,14 +753,28 @@ xfrm_policy_inexact_insert(struct xfrm_policy *policy, u8 dir, int excl)
 	if (!bin)
 		return ERR_PTR(-ENOMEM);
 
-	delpol = xfrm_policy_insert_list(&bin->hhead, policy, excl);
-	if (delpol && excl)
+	net = xp_net(policy);
+	lockdep_assert_held(&net->xfrm.xfrm_policy_lock);
+
+	if (xfrm_policy_inexact_insert_use_any_list(policy)) {
+		chain = &bin->hhead;
+		goto insert_to_list;
+	}
+
+	chain = &bin->hhead;
+insert_to_list:
+	delpol = xfrm_policy_insert_list(chain, policy, excl);
+	if (delpol && excl) {
+		__xfrm_policy_inexact_prune_bin(bin, false);
 		return ERR_PTR(-EEXIST);
+	}
 
-	net = xp_net(policy);
 	chain = &net->xfrm.policy_inexact[dir];
 	xfrm_policy_insert_inexact_list(chain, policy);
 
+	if (delpol)
+		__xfrm_policy_inexact_prune_bin(bin, false);
+
 	return delpol;
 }
 
@@ -733,6 +811,7 @@ static void xfrm_hash_rebuild(struct work_struct *work)
 	 * we start with destructive action.
 	 */
 	list_for_each_entry(policy, &net->xfrm.policy_all, walk.all) {
+		struct xfrm_pol_inexact_bin *bin;
 		u8 dbits, sbits;
 
 		dir = xfrm_policy_id2dir(policy->index);
@@ -761,7 +840,8 @@ static void xfrm_hash_rebuild(struct work_struct *work)
 		    policy->selector.prefixlen_s < sbits)
 			continue;
 
-		if (!xfrm_policy_inexact_alloc_bin(policy, dir))
+		bin = xfrm_policy_inexact_alloc_bin(policy, dir);
+		if (!bin)
 			goto out_unlock;
 	}
 
@@ -820,6 +900,7 @@ static void xfrm_hash_rebuild(struct work_struct *work)
 	}
 
 out_unlock:
+	__xfrm_policy_inexact_flush(net);
 	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 
 	mutex_unlock(&hash_resize_mutex);
@@ -977,6 +1058,7 @@ static void xfrm_policy_insert_inexact_list(struct hlist_head *chain,
 {
 	struct xfrm_policy *pol, *delpol = NULL;
 	struct hlist_node *newpos = NULL;
+	int i = 0;
 
 	hlist_for_each_entry(pol, chain, bydst_inexact_list) {
 		if (pol->type == policy->type &&
@@ -1000,6 +1082,11 @@ static void xfrm_policy_insert_inexact_list(struct hlist_head *chain,
 		hlist_add_behind_rcu(&policy->bydst_inexact_list, newpos);
 	else
 		hlist_add_head_rcu(&policy->bydst_inexact_list, chain);
+
+	hlist_for_each_entry(pol, chain, bydst_inexact_list) {
+		pol->pos = i;
+		i++;
+	}
 }
 
 static struct xfrm_policy *xfrm_policy_insert_list(struct hlist_head *chain,
@@ -1083,6 +1170,29 @@ int xfrm_policy_insert(int dir, struct xfrm_policy *policy, int excl)
 }
 EXPORT_SYMBOL(xfrm_policy_insert);
 
+static struct xfrm_policy *
+__xfrm_policy_bysel_ctx(struct hlist_head *chain, u32 mark, u32 if_id,
+			u8 type, int dir,
+			struct xfrm_selector *sel,
+			struct xfrm_sec_ctx *ctx)
+{
+	struct xfrm_policy *pol;
+
+	if (!chain)
+		return NULL;
+
+	hlist_for_each_entry(pol, chain, bydst) {
+		if (pol->type == type &&
+		    pol->if_id == if_id &&
+		    (mark & pol->mark.m) == pol->mark.v &&
+		    !selector_cmp(sel, &pol->selector) &&
+		    xfrm_sec_ctx_match(ctx, pol->security))
+			return pol;
+	}
+
+	return NULL;
+}
+
 struct xfrm_policy *xfrm_policy_bysel_ctx(struct net *net, u32 mark, u32 if_id,
 					  u8 type, int dir,
 					  struct xfrm_selector *sel,
@@ -1097,6 +1207,9 @@ struct xfrm_policy *xfrm_policy_bysel_ctx(struct net *net, u32 mark, u32 if_id,
 	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
 	chain = policy_hash_bysel(net, sel, sel->family, dir);
 	if (!chain) {
+		struct xfrm_pol_inexact_candidates cand;
+		int i;
+
 		bin = xfrm_policy_inexact_lookup(net, type,
 						 sel->family, dir, if_id);
 		if (!bin) {
@@ -1104,35 +1217,46 @@ struct xfrm_policy *xfrm_policy_bysel_ctx(struct net *net, u32 mark, u32 if_id,
 			return NULL;
 		}
 
-		chain = &bin->hhead;
+		if (!xfrm_policy_find_inexact_candidates(&cand, bin,
+							 &sel->saddr,
+							 &sel->daddr)) {
+			spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
+			return NULL;
+		}
+
+		pol = NULL;
+		for (i = 0; i < ARRAY_SIZE(cand.res); i++) {
+			struct xfrm_policy *tmp;
+
+			tmp = __xfrm_policy_bysel_ctx(cand.res[i], mark,
+						      if_id, type, dir,
+						      sel, ctx);
+			if (tmp && pol && tmp->pos < pol->pos)
+				pol = tmp;
+		}
+	} else {
+		pol = __xfrm_policy_bysel_ctx(chain, mark, if_id, type, dir,
+					      sel, ctx);
 	}
 
-	ret = NULL;
-	hlist_for_each_entry(pol, chain, bydst) {
-		if (pol->type == type &&
-		    pol->if_id == if_id &&
-		    (mark & pol->mark.m) == pol->mark.v &&
-		    !selector_cmp(sel, &pol->selector) &&
-		    xfrm_sec_ctx_match(ctx, pol->security)) {
-			xfrm_pol_hold(pol);
-			if (delete) {
-				*err = security_xfrm_policy_delete(
-								pol->security);
-				if (*err) {
-					spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
-					return pol;
-				}
-				__xfrm_policy_unlink(pol, dir);
-				xfrm_policy_inexact_delete_bin(net, bin);
+	if (pol) {
+		xfrm_pol_hold(pol);
+		if (delete) {
+			*err = security_xfrm_policy_delete(pol->security);
+			if (*err) {
+				spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
+				return pol;
 			}
-			ret = pol;
-			break;
+			__xfrm_policy_unlink(pol, dir);
 		}
+		ret = pol;
 	}
 	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 
 	if (ret && delete)
 		xfrm_policy_kill(ret);
+	if (bin && delete)
+		xfrm_policy_inexact_prune_bin(bin);
 	return ret;
 }
 EXPORT_SYMBOL(xfrm_policy_bysel_ctx);
@@ -1338,6 +1462,20 @@ static int xfrm_policy_match(const struct xfrm_policy *pol,
 	return ret;
 }
 
+static bool
+xfrm_policy_find_inexact_candidates(struct xfrm_pol_inexact_candidates *cand,
+				    struct xfrm_pol_inexact_bin *b,
+				    const xfrm_address_t *saddr,
+				    const xfrm_address_t *daddr)
+{
+	if (!b)
+		return false;
+
+	memset(cand, 0, sizeof(*cand));
+	cand->res[XFRM_POL_CAND_ANY] = &b->hhead;
+	return true;
+}
+
 static struct xfrm_pol_inexact_bin *
 xfrm_policy_inexact_lookup_rcu(struct net *net, u8 type, u16 family,
 			       u8 dir, u32 if_id)
@@ -1370,11 +1508,76 @@ xfrm_policy_inexact_lookup(struct net *net, u8 type, u16 family,
 	return bin;
 }
 
+static struct xfrm_policy *
+__xfrm_policy_eval_candidates(struct hlist_head *chain,
+			      struct xfrm_policy *prefer,
+			      const struct flowi *fl,
+			      u8 type, u16 family, int dir, u32 if_id)
+{
+	u32 priority = prefer ? prefer->priority : ~0u;
+	struct xfrm_policy *pol;
+
+	if (!chain)
+		return NULL;
+
+	hlist_for_each_entry_rcu(pol, chain, bydst) {
+		int err;
+
+		if (pol->priority > priority)
+			break;
+
+		err = xfrm_policy_match(pol, fl, type, family, dir, if_id);
+		if (err) {
+			if (err != -ESRCH)
+				return ERR_PTR(err);
+
+			continue;
+		}
+
+		if (prefer) {
+			/* matches.  Is it older than *prefer? */
+			if (pol->priority == priority &&
+			    prefer->pos < pol->pos)
+				return prefer;
+		}
+
+		return pol;
+	}
+
+	return NULL;
+}
+
+static struct xfrm_policy *
+xfrm_policy_eval_candidates(struct xfrm_pol_inexact_candidates *cand,
+			    struct xfrm_policy *prefer,
+			    const struct flowi *fl,
+			    u8 type, u16 family, int dir, u32 if_id)
+{
+	struct xfrm_policy *tmp;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(cand->res); i++) {
+		tmp = __xfrm_policy_eval_candidates(cand->res[i],
+						    prefer,
+						    fl, type, family, dir,
+						    if_id);
+		if (!tmp)
+			continue;
+
+		if (IS_ERR(tmp))
+			return tmp;
+		prefer = tmp;
+	}
+
+	return prefer;
+}
+
 static struct xfrm_policy *xfrm_policy_lookup_bytype(struct net *net, u8 type,
 						     const struct flowi *fl,
 						     u16 family, u8 dir,
 						     u32 if_id)
 {
+	struct xfrm_pol_inexact_candidates cand;
 	const xfrm_address_t *daddr, *saddr;
 	struct xfrm_pol_inexact_bin *bin;
 	struct xfrm_policy *pol, *ret;
@@ -1413,25 +1616,16 @@ static struct xfrm_policy *xfrm_policy_lookup_bytype(struct net *net, u8 type,
 		}
 	}
 	bin = xfrm_policy_inexact_lookup_rcu(net, type, family, dir, if_id);
-	if (!bin)
+	if (!bin || !xfrm_policy_find_inexact_candidates(&cand, bin, saddr,
+							 daddr))
 		goto skip_inexact;
-	chain = &bin->hhead;
-	hlist_for_each_entry_rcu(pol, chain, bydst) {
-		if ((pol->priority >= priority) && ret)
-			break;
 
-		err = xfrm_policy_match(pol, fl, type, family, dir, if_id);
-		if (err) {
-			if (err == -ESRCH)
-				continue;
-			else {
-				ret = ERR_PTR(err);
-				goto fail;
-			}
-		} else {
-			ret = pol;
-			break;
-		}
+	pol = xfrm_policy_eval_candidates(&cand, ret, fl, type,
+					  family, dir, if_id);
+	if (pol) {
+		ret = pol;
+		if (IS_ERR(pol))
+			goto fail;
 	}
 
 skip_inexact:
@@ -3168,7 +3362,7 @@ static int __net_init xfrm_policy_init(struct net *net)
 
 static void xfrm_policy_fini(struct net *net)
 {
-	struct xfrm_pol_inexact_bin *bin, *tmp;
+	struct xfrm_pol_inexact_bin *b, *t;
 	unsigned int sz;
 	int dir;
 
@@ -3195,11 +3389,10 @@ static void xfrm_policy_fini(struct net *net)
 	WARN_ON(!hlist_empty(net->xfrm.policy_byidx));
 	xfrm_hash_free(net->xfrm.policy_byidx, sz);
 
-	list_for_each_entry_safe(bin, tmp, &net->xfrm.inexact_bins,
-				 inexact_bins) {
-		WARN_ON(!hlist_empty(&bin->hhead));
-		xfrm_policy_inexact_delete_bin(net, bin);
-	}
+	spin_lock_bh(&net->xfrm.xfrm_policy_lock);
+	list_for_each_entry_safe(b, t, &net->xfrm.inexact_bins, inexact_bins)
+		__xfrm_policy_inexact_prune_bin(b, true);
+	spin_unlock_bh(&net->xfrm.xfrm_policy_lock);
 }
 
 static int __net_init xfrm_net_init(struct net *net)
-- 
2.18.1