netfilter: nf_tables: attach net_device to basechain

The device is part of the hook configuration, so instead of a global
configuration per table, set it to each of the basechain that we create.

This patch reworks ebddf1a8d78a ("netfilter: nf_tables: allow to bind table to
net_device").

Note that this adds a dev_name field in the nft_base_chain structure which is
required the netdev notification subscription that follows up in a patch to
handle gone net_devices.

Suggested-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_tables.h

@@ -791,6 +791,7 @@ struct nft_stats {
  *	@policy: default policy
  *	@stats: per-cpu chain stats
  *	@chain: the chain
+ *	@dev_name: device name that this base chain is attached to (if any)
  */
 struct nft_base_chain {
 	struct nf_hook_ops		ops[NFT_HOOK_OPS_MAX];
@@ -799,6 +800,7 @@ struct nft_base_chain {
 	u8				policy;
 	struct nft_stats __percpu	*stats;
 	struct nft_chain		chain;
+	char 				dev_name[IFNAMSIZ];
 };
 
 static inline struct nft_base_chain *nft_base_chain(const struct nft_chain *chain)
@@ -819,7 +821,6 @@ unsigned int nft_do_chain(struct nft_pktinfo *pkt,
  *	@use: number of chain references to this table
  *	@flags: table flag (see enum nft_table_flags)
  *	@name: name of the table
- *	@dev: this table is bound to this device (if any)
  */
 struct nft_table {
 	struct list_head		list;
@@ -829,7 +830,6 @@ struct nft_table {
 	u32				use;
 	u16				flags;
 	char				name[NFT_TABLE_MAXNAMELEN];
-	struct net_device		*dev;
 };
 
 enum nft_af_flags {

include/uapi/linux/netfilter/nf_tables.h

@@ -122,11 +122,13 @@ enum nft_list_attributes {
  *
  * @NFTA_HOOK_HOOKNUM: netfilter hook number (NLA_U32)
  * @NFTA_HOOK_PRIORITY: netfilter hook priority (NLA_U32)
+ * @NFTA_HOOK_DEV: netdevice name (NLA_STRING)
  */
 enum nft_hook_attributes {
 	NFTA_HOOK_UNSPEC,
 	NFTA_HOOK_HOOKNUM,
 	NFTA_HOOK_PRIORITY,
+	NFTA_HOOK_DEV,
 	__NFTA_HOOK_MAX
 };
 #define NFTA_HOOK_MAX		(__NFTA_HOOK_MAX - 1)
@@ -146,14 +148,12 @@ enum nft_table_flags {
  * @NFTA_TABLE_NAME: name of the table (NLA_STRING)
  * @NFTA_TABLE_FLAGS: bitmask of enum nft_table_flags (NLA_U32)
  * @NFTA_TABLE_USE: number of chains in this table (NLA_U32)
- * @NFTA_TABLE_DEV: net device name (NLA_STRING)
  */
 enum nft_table_attributes {
 	NFTA_TABLE_UNSPEC,
 	NFTA_TABLE_NAME,
 	NFTA_TABLE_FLAGS,
 	NFTA_TABLE_USE,
-	NFTA_TABLE_DEV,
 	__NFTA_TABLE_MAX
 };
 #define NFTA_TABLE_MAX		(__NFTA_TABLE_MAX - 1)

net/netfilter/nf_tables_api.c

@@ -399,8 +399,6 @@ static const struct nla_policy nft_table_policy[NFTA_TABLE_MAX + 1] = {
 	[NFTA_TABLE_NAME]	= { .type = NLA_STRING,
 				    .len = NFT_TABLE_MAXNAMELEN - 1 },
 	[NFTA_TABLE_FLAGS]	= { .type = NLA_U32 },
-	[NFTA_TABLE_DEV]	= { .type = NLA_STRING,
-				    .len = IFNAMSIZ - 1 },
 };
 
 static int nf_tables_fill_table_info(struct sk_buff *skb, struct net *net,
@@ -425,10 +423,6 @@ static int nf_tables_fill_table_info(struct sk_buff *skb, struct net *net,
 	    nla_put_be32(skb, NFTA_TABLE_USE, htonl(table->use)))
 		goto nla_put_failure;
 
-	if (table->dev &&
-	    nla_put_string(skb, NFTA_TABLE_DEV, table->dev->name))
-		goto nla_put_failure;
-
 	nlmsg_end(skb, nlh);
 	return 0;
 
@@ -614,11 +608,6 @@ static int nf_tables_updtable(struct nft_ctx *ctx)
 	if (flags == ctx->table->flags)
 		return 0;
 
-	if ((ctx->afi->flags & NFT_AF_NEEDS_DEV) &&
-	    ctx->nla[NFTA_TABLE_DEV] &&
-	    nla_strcmp(ctx->nla[NFTA_TABLE_DEV], ctx->table->dev->name))
-		return -EOPNOTSUPP;
-
 	trans = nft_trans_alloc(ctx, NFT_MSG_NEWTABLE,
 				sizeof(struct nft_trans_table));
 	if (trans == NULL)
@@ -656,7 +645,6 @@ static int nf_tables_newtable(struct sock *nlsk, struct sk_buff *skb,
 	struct nft_table *table;
 	struct net *net = sock_net(skb->sk);
 	int family = nfmsg->nfgen_family;
-	struct net_device *dev = NULL;
 	u32 flags = 0;
 	struct nft_ctx ctx;
 	int err;
@@ -691,20 +679,6 @@ static int nf_tables_newtable(struct sock *nlsk, struct sk_buff *skb,
 			return -EINVAL;
 	}
 
-	if (afi->flags & NFT_AF_NEEDS_DEV) {
-		char ifname[IFNAMSIZ];
-
-		if (!nla[NFTA_TABLE_DEV])
-			return -EOPNOTSUPP;
-
-		nla_strlcpy(ifname, nla[NFTA_TABLE_DEV], IFNAMSIZ);
-		dev = dev_get_by_name(net, ifname);
-		if (!dev)
-			return -ENOENT;
-	} else if (nla[NFTA_TABLE_DEV]) {
-		return -EOPNOTSUPP;
-	}
-
 	err = -EAFNOSUPPORT;
 	if (!try_module_get(afi->owner))
 		goto err1;
@@ -718,7 +692,6 @@ static int nf_tables_newtable(struct sock *nlsk, struct sk_buff *skb,
 	INIT_LIST_HEAD(&table->chains);
 	INIT_LIST_HEAD(&table->sets);
 	table->flags = flags;
-	table->dev   = dev;
 
 	nft_ctx_init(&ctx, skb, nlh, afi, table, NULL, nla);
 	err = nft_trans_table_add(&ctx, NFT_MSG_NEWTABLE);
@@ -732,9 +705,6 @@ err3:
 err2:
 	module_put(afi->owner);
 err1:
-	if (dev != NULL)
-		dev_put(dev);
-
 	return err;
 }
 
@@ -838,9 +808,6 @@ static void nf_tables_table_destroy(struct nft_ctx *ctx)
 {
 	BUG_ON(ctx->table->use > 0);
 
-	if (ctx->table->dev)
-		dev_put(ctx->table->dev);
-
 	kfree(ctx->table);
 	module_put(ctx->afi->owner);
 }
@@ -916,6 +883,8 @@ static const struct nla_policy nft_chain_policy[NFTA_CHAIN_MAX + 1] = {
 static const struct nla_policy nft_hook_policy[NFTA_HOOK_MAX + 1] = {
 	[NFTA_HOOK_HOOKNUM]	= { .type = NLA_U32 },
 	[NFTA_HOOK_PRIORITY]	= { .type = NLA_U32 },
+	[NFTA_HOOK_DEV]		= { .type = NLA_STRING,
+				    .len = IFNAMSIZ - 1 },
 };
 
 static int nft_dump_stats(struct sk_buff *skb, struct nft_stats __percpu *stats)
@@ -989,6 +958,9 @@ static int nf_tables_fill_chain_info(struct sk_buff *skb, struct net *net,
 			goto nla_put_failure;
 		if (nla_put_be32(skb, NFTA_HOOK_PRIORITY, htonl(ops->priority)))
 			goto nla_put_failure;
+		if (basechain->dev_name[0] &&
+		    nla_put_string(skb, NFTA_HOOK_DEV, basechain->dev_name))
+			goto nla_put_failure;
 		nla_nest_end(skb, nest);
 
 		if (nla_put_be32(skb, NFTA_CHAIN_POLICY,
@@ -1200,9 +1172,13 @@ static void nf_tables_chain_destroy(struct nft_chain *chain)
 	BUG_ON(chain->use > 0);
 
 	if (chain->flags & NFT_BASE_CHAIN) {
-		module_put(nft_base_chain(chain)->type->owner);
-		free_percpu(nft_base_chain(chain)->stats);
-		kfree(nft_base_chain(chain));
+		struct nft_base_chain *basechain = nft_base_chain(chain);
+
+		module_put(basechain->type->owner);
+		free_percpu(basechain->stats);
+		if (basechain->ops[0].dev != NULL)
+			dev_put(basechain->ops[0].dev);
+		kfree(basechain);
 	} else {
 		kfree(chain);
 	}
@@ -1221,6 +1197,7 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb,
 	struct nlattr *ha[NFTA_HOOK_MAX + 1];
 	struct net *net = sock_net(skb->sk);
 	int family = nfmsg->nfgen_family;
+	struct net_device *dev = NULL;
 	u8 policy = NF_ACCEPT;
 	u64 handle = 0;
 	unsigned int i;
@@ -1360,17 +1337,43 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb,
 			return -ENOENT;
 		hookfn = type->hooks[hooknum];
 
+		if (afi->flags & NFT_AF_NEEDS_DEV) {
+			char ifname[IFNAMSIZ];
+
+			if (!ha[NFTA_HOOK_DEV]) {
+				module_put(type->owner);
+				return -EOPNOTSUPP;
+			}
+
+			nla_strlcpy(ifname, ha[NFTA_HOOK_DEV], IFNAMSIZ);
+			dev = dev_get_by_name(net, ifname);
+			if (!dev) {
+				module_put(type->owner);
+				return -ENOENT;
+			}
+		} else if (ha[NFTA_HOOK_DEV]) {
+			module_put(type->owner);
+			return -EOPNOTSUPP;
+		}
+
 		basechain = kzalloc(sizeof(*basechain), GFP_KERNEL);
 		if (basechain == NULL) {
 			module_put(type->owner);
+			if (dev != NULL)
+				dev_put(dev);
 			return -ENOMEM;
 		}
 
+		if (dev != NULL)
+			strncpy(basechain->dev_name, dev->name, IFNAMSIZ);
+
 		if (nla[NFTA_CHAIN_COUNTERS]) {
 			stats = nft_stats_alloc(nla[NFTA_CHAIN_COUNTERS]);
 			if (IS_ERR(stats)) {
 				module_put(type->owner);
 				kfree(basechain);
+				if (dev != NULL)
+					dev_put(dev);
 				return PTR_ERR(stats);
 			}
 			basechain->stats = stats;
@@ -1379,6 +1382,8 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb,
 			if (stats == NULL) {
 				module_put(type->owner);
 				kfree(basechain);
+				if (dev != NULL)
+					dev_put(dev);
 				return -ENOMEM;
 			}
 			rcu_assign_pointer(basechain->stats, stats);
@@ -1396,7 +1401,7 @@ static int nf_tables_newchain(struct sock *nlsk, struct sk_buff *skb,
 			ops->priority	= priority;
 			ops->priv	= chain;
 			ops->hook	= afi->hooks[ops->hooknum];
-			ops->dev	= table->dev;
+			ops->dev	= dev;
 			if (hookfn)
 				ops->hook = hookfn;
 			if (afi->hook_ops_init)