1 files changed, 87 insertions, 18 deletions

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index d15d50de7980..da4c179a4d41 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -712,8 +712,23 @@ static const struct nla_policy u32_policy[TCA_U32_MAX + 1] = {
 	[TCA_U32_FLAGS]		= { .type = NLA_U32 },
 };
 
+static void u32_unbind_filter(struct tcf_proto *tp, struct tc_u_knode *n,
+			      struct nlattr **tb)
+{
+	if (tb[TCA_U32_CLASSID])
+		tcf_unbind_filter(tp, &n->res);
+}
+
+static void u32_bind_filter(struct tcf_proto *tp, struct tc_u_knode *n,
+			    unsigned long base, struct nlattr **tb)
+{
+	if (tb[TCA_U32_CLASSID]) {
+		n->res.classid = nla_get_u32(tb[TCA_U32_CLASSID]);
+		tcf_bind_filter(tp, &n->res, base);
+	}
+}
+
 static int u32_set_parms(struct net *net, struct tcf_proto *tp,
-			 unsigned long base,
 			 struct tc_u_knode *n, struct nlattr **tb,
 			 struct nlattr *est, u32 flags, u32 fl_flags,
 			 struct netlink_ext_ack *extack)
@@ -760,10 +775,6 @@ static int u32_set_parms(struct net *net, struct tcf_proto *tp,
 		if (ht_old)
 			ht_old->refcnt--;
 	}
-	if (tb[TCA_U32_CLASSID]) {
-		n->res.classid = nla_get_u32(tb[TCA_U32_CLASSID]);
-		tcf_bind_filter(tp, &n->res, base);
-	}
 
 	if (ifindex >= 0)
 		n->ifindex = ifindex;
@@ -815,7 +826,6 @@ static struct tc_u_knode *u32_init_knode(struct net *net, struct tcf_proto *tp,
 
 	new->ifindex = n->ifindex;
 	new->fshift = n->fshift;
-	new->res = n->res;
 	new->flags = n->flags;
 	RCU_INIT_POINTER(new->ht_down, ht);
 
@@ -903,17 +913,27 @@ static int u32_change(struct net *net, struct sk_buff *in_skb,
 		if (!new)
 			return -ENOMEM;
 
-		err = u32_set_parms(net, tp, base, new, tb,
-				    tca[TCA_RATE], flags, new->flags,
-				    extack);
+		err = u32_set_parms(net, tp, new, tb, tca[TCA_RATE],
+				    flags, new->flags, extack);
 
 		if (err) {
 			__u32_destroy_key(new);
 			return err;
 		}
 
+		u32_bind_filter(tp, new, base, tb);
+
 		err = u32_replace_hw_knode(tp, new, flags, extack);
 		if (err) {
+			u32_unbind_filter(tp, new, tb);
+
+			if (tb[TCA_U32_LINK]) {
+				struct tc_u_hnode *ht_old;
+
+				ht_old = rtnl_dereference(n->ht_down);
+				if (ht_old)
+					ht_old->refcnt++;
+			}
 			__u32_destroy_key(new);
 			return err;
 		}
@@ -1003,18 +1023,62 @@ static int u32_change(struct net *net, struct sk_buff *in_skb,
 		return -EINVAL;
 	}
 
+	/* At this point, we need to derive the new handle that will be used to
+	 * uniquely map the identity of this table match entry. The
+	 * identity of the entry that we need to construct is 32 bits made of:
+	 *     htid(12b):bucketid(8b):node/entryid(12b)
+	 *
+	 * At this point _we have the table(ht)_ in which we will insert this
+	 * entry. We carry the table's id in variable "htid".
+	 * Note that earlier code picked the ht selection either by a) the user
+	 * providing the htid specified via TCA_U32_HASH attribute or b) when
+	 * no such attribute is passed then the root ht, is default to at ID
+	 * 0x[800][00][000]. Rule: the root table has a single bucket with ID 0.
+	 * If OTOH the user passed us the htid, they may also pass a bucketid of
+	 * choice. 0 is fine. For example a user htid is 0x[600][01][000] it is
+	 * indicating hash bucketid of 1. Rule: the entry/node ID _cannot_ be
+	 * passed via the htid, so even if it was non-zero it will be ignored.
+	 *
+	 * We may also have a handle, if the user passed one. The handle also
+	 * carries the same addressing of htid(12b):bucketid(8b):node/entryid(12b).
+	 * Rule: the bucketid on the handle is ignored even if one was passed;
+	 * rather the value on "htid" is always assumed to be the bucketid.
+	 */
 	if (handle) {
+		/* Rule: The htid from handle and tableid from htid must match */
 		if (TC_U32_HTID(handle) && TC_U32_HTID(handle ^ htid)) {
 			NL_SET_ERR_MSG_MOD(extack, "Handle specified hash table address mismatch");
 			return -EINVAL;
 		}
-		handle = htid | TC_U32_NODE(handle);
-		err = idr_alloc_u32(&ht->handle_idr, NULL, &handle, handle,
-				    GFP_KERNEL);
-		if (err)
-			return err;
-	} else
+		/* Ok, so far we have a valid htid(12b):bucketid(8b) but we
+		 * need to finalize the table entry identification with the last
+		 * part - the node/entryid(12b)). Rule: Nodeid _cannot be 0_ for
+		 * entries. Rule: nodeid of 0 is reserved only for tables(see
+		 * earlier code which processes TC_U32_DIVISOR attribute).
+		 * Rule: The nodeid can only be derived from the handle (and not
+		 * htid).
+		 * Rule: if the handle specified zero for the node id example
+		 * 0x60000000, then pick a new nodeid from the pool of IDs
+		 * this hash table has been allocating from.
+		 * If OTOH it is specified (i.e for example the user passed a
+		 * handle such as 0x60000123), then we use it generate our final
+		 * handle which is used to uniquely identify the match entry.
+		 */
+		if (!TC_U32_NODE(handle)) {
+			handle = gen_new_kid(ht, htid);
+		} else {
+			handle = htid | TC_U32_NODE(handle);
+			err = idr_alloc_u32(&ht->handle_idr, NULL, &handle,
+					    handle, GFP_KERNEL);
+			if (err)
+				return err;
+		}
+	} else {
+		/* The user did not give us a handle; lets just generate one
+		 * from the table's pool of nodeids.
+		 */
 		handle = gen_new_kid(ht, htid);
+	}
 
 	if (tb[TCA_U32_SEL] == NULL) {
 		NL_SET_ERR_MSG_MOD(extack, "Selector not specified");
@@ -1074,15 +1138,18 @@ static int u32_change(struct net *net, struct sk_buff *in_skb,
 	}
 #endif
 
-	err = u32_set_parms(net, tp, base, n, tb, tca[TCA_RATE],
+	err = u32_set_parms(net, tp, n, tb, tca[TCA_RATE],
 			    flags, n->flags, extack);
+
+	u32_bind_filter(tp, n, base, tb);
+
 	if (err == 0) {
 		struct tc_u_knode __rcu **ins;
 		struct tc_u_knode *pins;
 
 		err = u32_replace_hw_knode(tp, n, flags, extack);
 		if (err)
-			goto errhw;
+			goto errunbind;
 
 		if (!tc_in_hw(n->flags))
 			n->flags |= TCA_CLS_FLAGS_NOT_IN_HW;
@@ -1100,7 +1167,9 @@ static int u32_change(struct net *net, struct sk_buff *in_skb,
 		return 0;
 	}
 
-errhw:
+errunbind:
+	u32_unbind_filter(tp, n, tb);
+
 #ifdef CONFIG_CLS_U32_MARK
 	free_percpu(n->pcpu_success);
 #endif