netfilter: nf_tables: use dev->name directly

no need to store the name in separate area.

Furthermore, it uses kmalloc but not kfree and most accesses seem to treat
it as char[IFNAMSIZ] not char *.

Remove this and use dev->name instead.

In case event zeroed dev, just omit the name in the dump.

Fixes: d92191aa84e5f1 ("netfilter: nf_tables: cache device name in flowtable object")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

2 files changed, 5 insertions, 10 deletions

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 4e82a4c49912..dc417ef0a0c5 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -1124,7 +1124,6 @@ struct nft_flowtable {
         u32                             genmask:2,
                                         use:30;
         u64                             handle;
-        char                            *dev_name[NFT_FLOWTABLE_DEVICE_MAX];
         /* runtime data below here */
         struct nf_hook_ops              *ops ____cacheline_aligned;
         struct nf_flowtable             data;
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index d41fa2c82f14..54a4f75ff9da 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5324,8 +5324,6 @@ static int nf_tables_flowtable_parse_hook(const struct nft_ctx *ctx,
                 flowtable->ops[i].priv          = &flowtable->data;
                 flowtable->ops[i].hook          = flowtable->data.type->hook;
                 flowtable->ops[i].dev           = dev_array[i];
-                flowtable->dev_name[i]          = kstrdup(dev_array[i]->name,
-                                                          GFP_KERNEL);
         }
 
         return err;
@@ -5483,10 +5481,8 @@ static int nf_tables_newflowtable(struct net *net, struct sock *nlsk,
 err6:
         i = flowtable->ops_len;
 err5:
-        for (k = i - 1; k >= 0; k--) {
-                kfree(flowtable->dev_name[k]);
+        for (k = i - 1; k >= 0; k--)
                 nf_unregister_net_hook(net, &flowtable->ops[k]);
-        }
 
         kfree(flowtable->ops);
 err4:
@@ -5585,9 +5581,10 @@ static int nf_tables_fill_flowtable_info(struct sk_buff *skb, struct net *net,
                 goto nla_put_failure;
 
         for (i = 0; i < flowtable->ops_len; i++) {
-                if (flowtable->dev_name[i][0] &&
-                    nla_put_string(skb, NFTA_DEVICE_NAME,
-                                   flowtable->dev_name[i]))
+                const struct net_device *dev = READ_ONCE(flowtable->ops[i].dev);
+
+                if (dev &&
+                    nla_put_string(skb, NFTA_DEVICE_NAME, dev->name))
                         goto nla_put_failure;
         }
         nla_nest_end(skb, nest_devs);
@@ -5829,7 +5826,6 @@ static void nft_flowtable_event(unsigned long event, struct net_device *dev,
                         continue;
 
                 nf_unregister_net_hook(dev_net(dev), &flowtable->ops[i]);
-                flowtable->dev_name[i][0] = '\0';
                 flowtable->ops[i].dev = NULL;
                 break;
         }