[nf-next PATCH v4 02/16] netfilter: nf_tables: Store user-defined hook ifname

[Phil Sutter <phil@nwl.cc>]

Prepare for hooks with NULL ops.dev pointer (due to non-existent device)
and store the interface name and length as specified by the user upon
creation. No functional change intended.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
Changes since v3:
- Assert max attribute length to avoid bogus values in hook->ifnamelen
  as per Florian's suggestion.
---
 include/net/netfilter/nf_tables.h |  2 ++
 net/netfilter/nf_tables_api.c     | 10 +++++++---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 49708e7e1339..73714e9d9392 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -1192,6 +1192,8 @@ struct nft_hook {
 	struct list_head	list;
 	struct nf_hook_ops	ops;
 	struct rcu_head		rcu;
+	char			ifname[IFNAMSIZ];
+	u8			ifnamelen;
 };
 
 /**
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index b85f15ed77ed..2ec3e407f91f 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2173,7 +2173,6 @@ static struct nft_hook *nft_netdev_hook_alloc(struct net *net,
 					      const struct nlattr *attr)
 {
 	struct net_device *dev;
-	char ifname[IFNAMSIZ];
 	struct nft_hook *hook;
 	int err;
 
@@ -2183,12 +2182,17 @@ static struct nft_hook *nft_netdev_hook_alloc(struct net *net,
 		goto err_hook_alloc;
 	}
 
-	nla_strscpy(ifname, attr, IFNAMSIZ);
+	err = nla_strscpy(hook->ifname, attr, IFNAMSIZ);
+	if (err < 0)
+		goto err_hook_dev;
+
+	hook->ifnamelen = nla_len(attr);
+
 	/* nf_tables_netdev_event() is called under rtnl_mutex, this is
 	 * indirectly serializing all the other holders of the commit_mutex with
 	 * the rtnl_mutex.
 	 */
-	dev = __dev_get_by_name(net, ifname);
+	dev = __dev_get_by_name(net, hook->ifname);
 	if (!dev) {
 		err = -ENOENT;
 		goto err_hook_dev;
-- 
2.43.0