netfilter: nf_tables: fix flowtable free

Every flow_offload entry is added into the table twice. Because of this,
rhashtable_free_and_destroy can't be used, since it would call kfree for
each flow_offload object twice.

This patch cleans up the flowtable via nf_flow_table_iterate() to
schedule removal of entries by setting on the dying bit, then there is
an explicitly invocation of the garbage collector to release resources.

Based on patch from Felix Fietkau.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

6 files changed, 26 insertions, 13 deletions

diff --git a/include/net/netfilter/nf_flow_table.h b/include/net/netfilter/nf_flow_table.h
index ed49cd169ecf..020ae903066f 100644
--- a/include/net/netfilter/nf_flow_table.h
+++ b/include/net/netfilter/nf_flow_table.h
@@ -14,6 +14,7 @@ struct nf_flowtable_type {
         struct list_head                list;
         int                             family;
         void                            (*gc)(struct work_struct *work);
+        void                            (*free)(struct nf_flowtable *ft);
         const struct rhashtable_params  *params;
         nf_hookfn                       *hook;
         struct module                   *owner;
@@ -98,6 +99,7 @@ int nf_flow_table_iterate(struct nf_flowtable *flow_table,
 
 void nf_flow_table_cleanup(struct net *net, struct net_device *dev);
 
+void nf_flow_table_free(struct nf_flowtable *flow_table);
 void nf_flow_offload_work_gc(struct work_struct *work);
 extern const struct rhashtable_params nf_flow_offload_rhash_params;
 
diff --git a/net/ipv4/netfilter/nf_flow_table_ipv4.c b/net/ipv4/netfilter/nf_flow_table_ipv4.c
index b2d01eb25f2c..25d2975da156 100644
--- a/net/ipv4/netfilter/nf_flow_table_ipv4.c
+++ b/net/ipv4/netfilter/nf_flow_table_ipv4.c
@@ -260,6 +260,7 @@ static struct nf_flowtable_type flowtable_ipv4 = {
         .family         = NFPROTO_IPV4,
         .params         = &nf_flow_offload_rhash_params,
         .gc             = nf_flow_offload_work_gc,
+        .free           = nf_flow_table_free,
         .hook           = nf_flow_offload_ip_hook,
         .owner          = THIS_MODULE,
 };
diff --git a/net/ipv6/netfilter/nf_flow_table_ipv6.c b/net/ipv6/netfilter/nf_flow_table_ipv6.c
index fff21602875a..d346705d6ee6 100644
--- a/net/ipv6/netfilter/nf_flow_table_ipv6.c
+++ b/net/ipv6/netfilter/nf_flow_table_ipv6.c
@@ -253,6 +253,7 @@ static struct nf_flowtable_type flowtable_ipv6 = {
         .family         = NFPROTO_IPV6,
         .params         = &nf_flow_offload_rhash_params,
         .gc             = nf_flow_offload_work_gc,
+        .free           = nf_flow_table_free,
         .hook           = nf_flow_offload_ipv6_hook,
         .owner          = THIS_MODULE,
 };
diff --git a/net/netfilter/nf_flow_table.c b/net/netfilter/nf_flow_table.c
index 04c08f6b9015..c17f1af42daa 100644
--- a/net/netfilter/nf_flow_table.c
+++ b/net/netfilter/nf_flow_table.c
@@ -232,19 +232,16 @@ static inline bool nf_flow_is_dying(const struct flow_offload *flow)
         return flow->flags & FLOW_OFFLOAD_DYING;
 }
 
-void nf_flow_offload_work_gc(struct work_struct *work)
+static int nf_flow_offload_gc_step(struct nf_flowtable *flow_table)
 {
         struct flow_offload_tuple_rhash *tuplehash;
-        struct nf_flowtable *flow_table;
         struct rhashtable_iter hti;
         struct flow_offload *flow;
         int err;
 
-        flow_table = container_of(work, struct nf_flowtable, gc_work.work);
-
         err = rhashtable_walk_init(&flow_table->rhashtable, &hti, GFP_KERNEL);
         if (err)
-                goto schedule;
+                return 0;
 
         rhashtable_walk_start(&hti);
 
@@ -270,7 +267,16 @@ void nf_flow_offload_work_gc(struct work_struct *work)
 out:
         rhashtable_walk_stop(&hti);
         rhashtable_walk_exit(&hti);
-schedule:
+
+        return 1;
+}
+
+void nf_flow_offload_work_gc(struct work_struct *work)
+{
+        struct nf_flowtable *flow_table;
+
+        flow_table = container_of(work, struct nf_flowtable, gc_work.work);
+        nf_flow_offload_gc_step(flow_table);
         queue_delayed_work(system_power_efficient_wq, &flow_table->gc_work, HZ);
 }
 EXPORT_SYMBOL_GPL(nf_flow_offload_work_gc);
@@ -449,5 +455,12 @@ void nf_flow_table_cleanup(struct net *net, struct net_device *dev)
 }
 EXPORT_SYMBOL_GPL(nf_flow_table_cleanup);
 
+void nf_flow_table_free(struct nf_flowtable *flow_table)
+{
+        nf_flow_table_iterate(flow_table, nf_flow_table_do_cleanup, NULL);
+        WARN_ON(!nf_flow_offload_gc_step(flow_table));
+}
+EXPORT_SYMBOL_GPL(nf_flow_table_free);
+
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
diff --git a/net/netfilter/nf_flow_table_inet.c b/net/netfilter/nf_flow_table_inet.c
index 281209aeba8f..375a1881d93d 100644
--- a/net/netfilter/nf_flow_table_inet.c
+++ b/net/netfilter/nf_flow_table_inet.c
@@ -24,6 +24,7 @@ static struct nf_flowtable_type flowtable_inet = {
         .family         = NFPROTO_INET,
         .params         = &nf_flow_offload_rhash_params,
         .gc             = nf_flow_offload_work_gc,
+        .free           = nf_flow_table_free,
         .hook           = nf_flow_offload_inet_hook,
         .owner          = THIS_MODULE,
 };
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 07dd1fac78a8..8b9fe30de0cd 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5399,17 +5399,12 @@ err:
         nfnetlink_set_err(ctx->net, ctx->portid, NFNLGRP_NFTABLES, -ENOBUFS);
 }
 
-static void nft_flowtable_destroy(void *ptr, void *arg)
-{
-        kfree(ptr);
-}
-
 static void nf_tables_flowtable_destroy(struct nft_flowtable *flowtable)
 {
         cancel_delayed_work_sync(&flowtable->data.gc_work);
         kfree(flowtable->name);
-        rhashtable_free_and_destroy(&flowtable->data.rhashtable,
-                                    nft_flowtable_destroy, NULL);
+        flowtable->data.type->free(&flowtable->data);
+        rhashtable_destroy(&flowtable->data.rhashtable);
         module_put(flowtable->data.type->owner);
 }