netfilter: nftables: add nft_pernet() helper function

jira VULN-429
pre-cve CVE-2023-4244
commit-author Pablo Neira Ayuso <pablo@netfilter.org>
commit d59d2f8
upstream-diff So many conflicts when trying to cherry pick this but
they're all very similar and didn't have much trouble picking them
out.  As per previous commits in this series I've used rocky8_10
branch as the source of truth when resolving conflicts.

Consolidate call to net_generic(net, nf_tables_net_id) in this
wrapper function.

	Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
(cherry picked from commit d59d2f8)
	Signed-off-by: Greg Rose <g.v.rose@ciq.com>

Author: gvrose8192

include/net/netfilter/nf_tables.h

@@ -13,6 +13,7 @@
 #include <net/netfilter/nf_flow_table.h>
 #include <net/netlink.h>
 #include <net/flow_offload.h>
+#include <net/netns/generic.h>
 
 struct module;
 
@@ -1561,4 +1562,17 @@ __printf(2, 3) int nft_request_module(struct net *net, const char *fmt, ...);
 #else
 static inline int nft_request_module(struct net *net, const char *fmt, ...) { return -ENOENT; }
 #endif
+
+struct nftables_pernet {
+	u64                     tstamp;
+	unsigned int            gc_seq;
+};
+
+extern unsigned int nf_tables_net_id;
+
+static inline struct nftables_pernet *nft_pernet(const struct net *net)
+{
+	return net_generic(net, nf_tables_net_id);
+}
+
 #endif /* _NET_NF_TABLES_H */

net/netfilter/nf_tables_api.c

@@ -28,6 +28,9 @@
 
 #define NFT_MODULE_AUTOLOAD_LIMIT (MODULE_NAME_LEN - sizeof("nft-expr-255-"))
 
+unsigned int nf_tables_net_id __read_mostly;
+EXPORT_SYMBOL_GPL(nf_tables_net_id);
+
 static LIST_HEAD(nf_tables_expressions);
 static LIST_HEAD(nf_tables_objects);
 static LIST_HEAD(nf_tables_flowtables);
@@ -3593,8 +3596,8 @@ static struct nft_set *nft_set_lookup_byid(const struct net *net,
 					   const struct nft_table *table,
 					   const struct nlattr *nla, u8 genmask)
 {
-	struct nft_trans *trans;
 	u32 id = ntohl(nla_get_be32(nla));
+	struct nft_trans *trans;
 
 	list_for_each_entry(trans, &net->nft.commit_list, list) {
 		if (trans->msg_type == NFT_MSG_NEWSET) {
@@ -3837,8 +3840,8 @@ static void nf_tables_set_notify(const struct nft_ctx *ctx,
 				 const struct nft_set *set, int event,
 			         gfp_t gfp_flags)
 {
-	u32 portid = ctx->portid;
 	struct sk_buff *skb;
+	u32 portid = ctx->portid;
 	u16 flags = 0;
 	int err;
 
@@ -4786,7 +4789,7 @@ static int nf_tables_dump_set(struct sk_buff *skb, struct netlink_callback *cb)
 	rcu_read_lock();
 	cb->seq = READ_ONCE(net->nft.base_seq);
 
-    list_for_each_entry_rcu(table, &net->nft.tables, list) {
+	list_for_each_entry_rcu(table, &net->nft.tables, list) {
 		if (dump_ctx->ctx.family != NFPROTO_UNSPEC &&
 		    dump_ctx->ctx.family != table->family)
 			continue;
@@ -7955,14 +7958,31 @@ static void nft_set_commit_update(struct list_head *set_update_list)
 	}
 }
 
+static unsigned int nft_gc_seq_begin(struct nftables_pernet *nft_net)
+{
+        unsigned int gc_seq;
+
+        /* Bump gc counter, it becomes odd, this is the busy mark. */
+        gc_seq = READ_ONCE(nft_net->gc_seq);
+        WRITE_ONCE(nft_net->gc_seq, ++gc_seq);
+
+        return gc_seq;
+}
+
+static void nft_gc_seq_end(struct nftables_pernet *nft_net, unsigned int gc_seq)
+{
+        WRITE_ONCE(nft_net->gc_seq, ++gc_seq);
+}
+
 static int nf_tables_commit(struct net *net, struct sk_buff *skb)
 {
+	struct nftables_pernet *nft_net = nft_pernet(net);
 	struct nft_trans *trans, *next;
+	unsigned int base_seq, gc_seq;
 	LIST_HEAD(set_update_list);
 	struct nft_trans_elem *te;
 	struct nft_chain *chain;
 	struct nft_table *table;
-	unsigned int base_seq;
 	LIST_HEAD(adl);
 	int err;
 
@@ -8013,6 +8033,8 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
 
 	WRITE_ONCE(net->nft.base_seq, base_seq);
 
+	gc_seq = nft_gc_seq_begin(nft_net);
+
 	/* step 3. Start new generation, rules_gen_X now in use. */
 	net->nft.gencursor = nft_gencursor_next(net);
 
@@ -8391,18 +8413,25 @@ static void nf_tables_cleanup(struct net *net)
 static int nf_tables_abort(struct net *net, struct sk_buff *skb,
 			   enum nfnl_abort_action action)
 {
-	int ret = __nf_tables_abort(net, action);
+	struct nftables_pernet *nft_net = nft_pernet(net);
+	unsigned int gc_seq;
+	int ret;
 
+	gc_seq = nft_gc_seq_begin(nft_net);
+        ret = __nf_tables_abort(net, action);
+        nft_gc_seq_end(nft_net, gc_seq);
 	mutex_unlock(&net->nft_commit_mutex);
 
 	return ret;
 }
 
 static bool nf_tables_valid_genid(struct net *net, u32 genid)
 {
+	struct nftables_pernet *nft_net = nft_pernet(net);
 	bool genid_ok;
 
 	mutex_lock(&net->nft_commit_mutex);
+	nft_net->tstamp = get_jiffies_64();
 
 	genid_ok = genid == 0 || net->nft.base_seq == genid;
 	if (!genid_ok)
@@ -9012,13 +9041,16 @@ static void __nft_release_tables(struct net *net)
 
 static int __net_init nf_tables_init_net(struct net *net)
 {
+	struct nftables_pernet *nft_net = nft_pernet(net);
+
 	INIT_LIST_HEAD(&net->nft.tables);
 	INIT_LIST_HEAD(&net->nft.commit_list);
 	INIT_LIST_HEAD(&net->nft_module_list);
 	INIT_LIST_HEAD(&net->nft_notify_list);
 	mutex_init(&net->nft_commit_mutex);
 	net->nft.base_seq = 1;
 	net->nft.validate_state = NFT_VALIDATE_SKIP;
+	nft_net->gc_seq = 0;
 
 	return 0;
 }
@@ -9032,11 +9064,21 @@ static void __net_exit nf_tables_pre_exit_net(struct net *net)
 
 static void __net_exit nf_tables_exit_net(struct net *net)
 {
+	struct nftables_pernet *nft_net = nft_pernet(net);
+	unsigned int gc_seq;
+
 	mutex_lock(&net->nft_commit_mutex);
+
+	gc_seq = nft_gc_seq_begin(nft_net);
+
 	if (!list_empty(&net->nft.commit_list) ||
 	    !list_empty(&net->nft_module_list))
 		__nf_tables_abort(net, NFNL_ABORT_NONE);
+
 	__nft_release_tables(net);
+
+	nft_gc_seq_end(nft_net, gc_seq);
+
 	mutex_unlock(&net->nft_commit_mutex);
 	WARN_ON_ONCE(!list_empty(&net->nft.tables));
 	WARN_ON_ONCE(!list_empty(&net->nft_module_list));