[nf-next PATCH v4 14/16] netfilter: nf_tables: Support wildcard netdev hook specs

[Phil Sutter <phil@nwl.cc>]

User space may pass non-nul-terminated NFTA_DEVICE_NAME attribute values
to indicate a suffix wildcard.
Expect for multiple devices to match the given prefix in
nft_netdev_hook_alloc() and populate 'ops_list' with them all.
When checking for duplicate hooks, compare the shortest prefix so a
device may never match more than a single hook spec.
Finally respect the stored prefix length when hooking into new devices
from event handlers.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 net/netfilter/nf_tables_api.c    | 33 ++++++++++++++++----------------
 net/netfilter/nft_chain_filter.c |  2 +-
 2 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 4d40c1905735..ba2038ea56d2 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2222,7 +2222,7 @@ static struct nft_hook *nft_netdev_hook_alloc(struct net *net,
 
 	err = nla_strscpy(hook->ifname, attr, IFNAMSIZ);
 	if (err < 0)
-		goto err_hook_dev;
+		goto err_ops_alloc;
 
 	hook->ifnamelen = nla_len(attr);
 
@@ -2230,24 +2230,22 @@ static struct nft_hook *nft_netdev_hook_alloc(struct net *net,
 	 * indirectly serializing all the other holders of the commit_mutex with
 	 * the rtnl_mutex.
 	 */
-	dev = __dev_get_by_name(net, hook->ifname);
-	if (!dev) {
-		err = -ENOENT;
-		goto err_hook_dev;
-	}
+	for_each_netdev(net, dev) {
+		if (strncmp(dev->name, hook->ifname, hook->ifnamelen))
+			continue;
 
-	ops = kzalloc(sizeof(struct nf_hook_ops), GFP_KERNEL_ACCOUNT);
-	if (!ops) {
-		err = -ENOMEM;
-		goto err_hook_dev;
+		ops = kzalloc(sizeof(struct nf_hook_ops), GFP_KERNEL_ACCOUNT);
+		if (!ops) {
+			err = -ENOMEM;
+			goto err_ops_alloc;
+		}
+		ops->dev = dev;
+		list_add_tail(&ops->list, &hook->ops_list);
 	}
-	ops->dev = dev;
-	list_add_tail(&ops->list, &hook->ops_list);
-
 	return hook;
 
-err_hook_dev:
-	kfree(hook);
+err_ops_alloc:
+	nft_netdev_hook_free(hook);
 err_hook_alloc:
 	return ERR_PTR(err);
 }
@@ -2258,7 +2256,8 @@ static struct nft_hook *nft_hook_list_find(struct list_head *hook_list,
 	struct nft_hook *hook;
 
 	list_for_each_entry(hook, hook_list, list) {
-		if (!strcmp(hook->ifname, this->ifname))
+		if (!strncmp(hook->ifname, this->ifname,
+			     min(hook->ifnamelen, this->ifnamelen)))
 			return hook;
 	}
 
@@ -9337,7 +9336,7 @@ static int nft_flowtable_event(unsigned long event, struct net_device *dev,
 			kfree_rcu(ops, rcu);
 			break;
 		case NETDEV_REGISTER:
-			if (strcmp(hook->ifname, dev->name))
+			if (strncmp(hook->ifname, dev->name, hook->ifnamelen))
 				continue;
 			ops = kzalloc(sizeof(struct nf_hook_ops),
 				      GFP_KERNEL_ACCOUNT);
diff --git a/net/netfilter/nft_chain_filter.c b/net/netfilter/nft_chain_filter.c
index 0f5706addfcb..f7290dc20a53 100644
--- a/net/netfilter/nft_chain_filter.c
+++ b/net/netfilter/nft_chain_filter.c
@@ -338,7 +338,7 @@ static int nft_netdev_event(unsigned long event, struct net_device *dev,
 			kfree_rcu(ops, rcu);
 			break;
 		case NETDEV_REGISTER:
-			if (strcmp(hook->ifname, dev->name))
+			if (strncmp(hook->ifname, dev->name, hook->ifnamelen))
 				continue;
 
 			ops = kmemdup(&basechain->ops,
-- 
2.43.0