From 8d738c1869f611955d91d8d0fd0012d9ef207201 Mon Sep 17 00:00:00 2001
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Mon, 6 Jan 2025 23:40:50 +0100
Subject: netfilter: nf_tables: fix set size with rbtree backend

The existing rbtree implementation uses singleton elements to represent
ranges, however, userspace provides a set size according to the number
of ranges in the set.

Adjust provided userspace set size to the number of singleton elements
in the kernel by multiplying the range by two.

Check if the no-match all-zero element is already in the set, in such
case release one slot in the set size.

Fixes: 0ed6389c483d ("netfilter: nf_tables: rename set implementations")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/net/netfilter/nf_tables.h | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'include/net')

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 0027beca5cd5..f6958118986a 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -442,6 +442,9 @@ struct nft_set_ext;
  *	@remove: remove element from set
  *	@walk: iterate over all set elements
  *	@get: get set elements
+ *	@ksize: kernel set size
+ * 	@usize: userspace set size
+ *	@adjust_maxsize: delta to adjust maximum set size
  *	@commit: commit set elements
  *	@abort: abort set elements
  *	@privsize: function to return size of set private data
@@ -495,6 +498,9 @@ struct nft_set_ops {
 					       const struct nft_set *set,
 					       const struct nft_set_elem *elem,
 					       unsigned int flags);
+	u32				(*ksize)(u32 size);
+	u32				(*usize)(u32 size);
+	u32				(*adjust_maxsize)(const struct nft_set *set);
 	void				(*commit)(struct nft_set *set);
 	void				(*abort)(const struct nft_set *set);
 	u64				(*privsize)(const struct nlattr * const nla[],
-- 
cgit v1.2.3


From b7c2d793c28cda7dbb67d6b427e3280b7c1e601a Mon Sep 17 00:00:00 2001
From: Phil Sutter <phil@nwl.cc>
Date: Thu, 9 Jan 2025 18:31:33 +0100
Subject: netfilter: nf_tables: Store user-defined hook ifname

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>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/net/netfilter/nf_tables.h |  2 ++
 net/netfilter/nf_tables_api.c     | 10 +++++++---
 2 files changed, 9 insertions(+), 3 deletions(-)

(limited to 'include/net')

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index f6958118986a..bd93d085b6fb 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -1201,6 +1201,8 @@ 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 e41c77e5eefd..95d8d33589b1 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2276,7 +2276,6 @@ 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;
 
@@ -2286,12 +2285,17 @@ 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;
-- 
cgit v1.2.3


From fc0133428e7ad65aa6b7c8e65ccfe86e469e4512 Mon Sep 17 00:00:00 2001
From: Phil Sutter <phil@nwl.cc>
Date: Thu, 9 Jan 2025 18:31:36 +0100
Subject: netfilter: nf_tables: Tolerate chains with no remaining hooks

Do not drop a netdev-family chain if the last interface it is registered
for vanishes. Users dumping and storing the ruleset upon shutdown to
restore it upon next boot may otherwise lose the chain and all contained
rules. They will still lose the list of devices, a later patch will fix
that. For now, this aligns the event handler's behaviour with that for
flowtables.
The controversal situation at netns exit should be no problem here:
event handler will unregister the hooks, core nftables cleanup code will
drop the chain itself.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/net/netfilter/nf_tables.h |  2 --
 net/netfilter/nf_tables_api.c     | 41 ---------------------------------------
 net/netfilter/nft_chain_filter.c  | 29 +++++++--------------------
 3 files changed, 7 insertions(+), 65 deletions(-)

(limited to 'include/net')

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index bd93d085b6fb..60d5dcdb289c 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -1238,8 +1238,6 @@ static inline bool nft_is_base_chain(const struct nft_chain *chain)
 	return chain->flags & NFT_CHAIN_BASE;
 }
 
-int __nft_release_basechain(struct nft_ctx *ctx);
-
 unsigned int nft_do_chain(struct nft_pktinfo *pkt, void *priv);
 
 static inline bool nft_use_inc(u32 *use)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index ed15c52e3c65..667459256e4c 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -11741,47 +11741,6 @@ int nft_data_dump(struct sk_buff *skb, int attr, const struct nft_data *data,
 }
 EXPORT_SYMBOL_GPL(nft_data_dump);
 
-static void __nft_release_basechain_now(struct nft_ctx *ctx)
-{
-	struct nft_rule *rule, *nr;
-
-	list_for_each_entry_safe(rule, nr, &ctx->chain->rules, list) {
-		list_del(&rule->list);
-		nf_tables_rule_release(ctx, rule);
-	}
-	nf_tables_chain_destroy(ctx->chain);
-}
-
-int __nft_release_basechain(struct nft_ctx *ctx)
-{
-	struct nft_rule *rule;
-
-	if (WARN_ON_ONCE(!nft_is_base_chain(ctx->chain)))
-		return 0;
-
-	nf_tables_unregister_hook(ctx->net, ctx->chain->table, ctx->chain);
-	list_for_each_entry(rule, &ctx->chain->rules, list)
-		nft_use_dec(&ctx->chain->use);
-
-	nft_chain_del(ctx->chain);
-	nft_use_dec(&ctx->table->use);
-
-	if (!maybe_get_net(ctx->net)) {
-		__nft_release_basechain_now(ctx);
-		return 0;
-	}
-
-	/* wait for ruleset dumps to complete.  Owning chain is no longer in
-	 * lists, so new dumps can't find any of these rules anymore.
-	 */
-	synchronize_rcu();
-
-	__nft_release_basechain_now(ctx);
-	put_net(ctx->net);
-	return 0;
-}
-EXPORT_SYMBOL_GPL(__nft_release_basechain);
-
 static void __nft_release_hook(struct net *net, struct nft_table *table)
 {
 	struct nft_flowtable *flowtable;
diff --git a/net/netfilter/nft_chain_filter.c b/net/netfilter/nft_chain_filter.c
index 7010541fcca6..543f258b7c6b 100644
--- a/net/netfilter/nft_chain_filter.c
+++ b/net/netfilter/nft_chain_filter.c
@@ -322,34 +322,19 @@ static void nft_netdev_event(unsigned long event, struct net_device *dev,
 			     struct nft_ctx *ctx)
 {
 	struct nft_base_chain *basechain = nft_base_chain(ctx->chain);
-	struct nft_hook *hook, *found = NULL;
-	int n = 0;
+	struct nft_hook *hook;
 
 	list_for_each_entry(hook, &basechain->hook_list, list) {
-		if (hook->ops.dev == dev)
-			found = hook;
-
-		n++;
-	}
-	if (!found)
-		return;
+		if (hook->ops.dev != dev)
+			continue;
 
-	if (n > 1) {
 		if (!(ctx->chain->table->flags & NFT_TABLE_F_DORMANT))
-			nf_unregister_net_hook(ctx->net, &found->ops);
+			nf_unregister_net_hook(ctx->net, &hook->ops);
 
-		list_del_rcu(&found->list);
-		kfree_rcu(found, rcu);
-		return;
+		list_del_rcu(&hook->list);
+		kfree_rcu(hook, rcu);
+		break;
 	}
-
-	/* UNREGISTER events are also happening on netns exit.
-	 *
-	 * Although nf_tables core releases all tables/chains, only this event
-	 * handler provides guarantee that hook->ops.dev is still accessible,
-	 * so we cannot skip exiting net namespaces.
-	 */
-	__nft_release_basechain(ctx);
 }
 
 static int nf_tables_netdev_event(struct notifier_block *this,
-- 
cgit v1.2.3


From 31768596b15aa8c9c55f078acad29d0238c8269b Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Tue, 14 Jan 2025 00:50:35 +0100
Subject: netfilter: conntrack: remove skb argument from nf_ct_refresh

Its not used (and could be NULL), so remove it.
This allows to use nf_ct_refresh in places where we don't have
an skb without having to double-check that skb == NULL would be safe.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/net/netfilter/nf_conntrack.h   | 8 +++-----
 net/netfilter/nf_conntrack_amanda.c    | 2 +-
 net/netfilter/nf_conntrack_broadcast.c | 2 +-
 net/netfilter/nf_conntrack_core.c      | 7 +++----
 net/netfilter/nf_conntrack_h323_main.c | 4 ++--
 net/netfilter/nf_conntrack_sip.c       | 4 ++--
 net/netfilter/nft_ct.c                 | 2 +-
 7 files changed, 13 insertions(+), 16 deletions(-)

(limited to 'include/net')

diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index cba3ccf03fcc..3cbf29dd0b71 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -204,8 +204,7 @@ bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff,
 		       struct nf_conntrack_tuple *tuple);
 
 void __nf_ct_refresh_acct(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
-			  const struct sk_buff *skb,
-			  u32 extra_jiffies, bool do_acct);
+			  u32 extra_jiffies, unsigned int bytes);
 
 /* Refresh conntrack for this many jiffies and do accounting */
 static inline void nf_ct_refresh_acct(struct nf_conn *ct,
@@ -213,15 +212,14 @@ static inline void nf_ct_refresh_acct(struct nf_conn *ct,
 				      const struct sk_buff *skb,
 				      u32 extra_jiffies)
 {
-	__nf_ct_refresh_acct(ct, ctinfo, skb, extra_jiffies, true);
+	__nf_ct_refresh_acct(ct, ctinfo, extra_jiffies, skb->len);
 }
 
 /* Refresh conntrack for this many jiffies */
 static inline void nf_ct_refresh(struct nf_conn *ct,
-				 const struct sk_buff *skb,
 				 u32 extra_jiffies)
 {
-	__nf_ct_refresh_acct(ct, 0, skb, extra_jiffies, false);
+	__nf_ct_refresh_acct(ct, 0, extra_jiffies, 0);
 }
 
 /* kill conntrack and do accounting */
diff --git a/net/netfilter/nf_conntrack_amanda.c b/net/netfilter/nf_conntrack_amanda.c
index d011d2eb0848..7be4c35e4795 100644
--- a/net/netfilter/nf_conntrack_amanda.c
+++ b/net/netfilter/nf_conntrack_amanda.c
@@ -106,7 +106,7 @@ static int amanda_help(struct sk_buff *skb,
 
 	/* increase the UDP timeout of the master connection as replies from
 	 * Amanda clients to the server can be quite delayed */
-	nf_ct_refresh(ct, skb, master_timeout * HZ);
+	nf_ct_refresh(ct, master_timeout * HZ);
 
 	/* No data? */
 	dataoff = protoff + sizeof(struct udphdr);
diff --git a/net/netfilter/nf_conntrack_broadcast.c b/net/netfilter/nf_conntrack_broadcast.c
index cfa0fe0356de..a7552a46d6ac 100644
--- a/net/netfilter/nf_conntrack_broadcast.c
+++ b/net/netfilter/nf_conntrack_broadcast.c
@@ -75,7 +75,7 @@ int nf_conntrack_broadcast_help(struct sk_buff *skb,
 	nf_ct_expect_related(exp, 0);
 	nf_ct_expect_put(exp);
 
-	nf_ct_refresh(ct, skb, timeout * HZ);
+	nf_ct_refresh(ct, timeout * HZ);
 out:
 	return NF_ACCEPT;
 }
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 456446d7af20..0149d482adaa 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -2089,9 +2089,8 @@ EXPORT_SYMBOL_GPL(nf_conntrack_in);
 /* Refresh conntrack for this many jiffies and do accounting if do_acct is 1 */
 void __nf_ct_refresh_acct(struct nf_conn *ct,
 			  enum ip_conntrack_info ctinfo,
-			  const struct sk_buff *skb,
 			  u32 extra_jiffies,
-			  bool do_acct)
+			  unsigned int bytes)
 {
 	/* Only update if this is not a fixed timeout */
 	if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status))
@@ -2104,8 +2103,8 @@ void __nf_ct_refresh_acct(struct nf_conn *ct,
 	if (READ_ONCE(ct->timeout) != extra_jiffies)
 		WRITE_ONCE(ct->timeout, extra_jiffies);
 acct:
-	if (do_acct)
-		nf_ct_acct_update(ct, CTINFO2DIR(ctinfo), skb->len);
+	if (bytes)
+		nf_ct_acct_update(ct, CTINFO2DIR(ctinfo), bytes);
 }
 EXPORT_SYMBOL_GPL(__nf_ct_refresh_acct);
 
diff --git a/net/netfilter/nf_conntrack_h323_main.c b/net/netfilter/nf_conntrack_h323_main.c
index 5a9bce24f3c3..14f73872f647 100644
--- a/net/netfilter/nf_conntrack_h323_main.c
+++ b/net/netfilter/nf_conntrack_h323_main.c
@@ -1385,7 +1385,7 @@ static int process_rcf(struct sk_buff *skb, struct nf_conn *ct,
 	if (info->timeout > 0) {
 		pr_debug("nf_ct_ras: set RAS connection timeout to "
 			 "%u seconds\n", info->timeout);
-		nf_ct_refresh(ct, skb, info->timeout * HZ);
+		nf_ct_refresh(ct, info->timeout * HZ);
 
 		/* Set expect timeout */
 		spin_lock_bh(&nf_conntrack_expect_lock);
@@ -1433,7 +1433,7 @@ static int process_urq(struct sk_buff *skb, struct nf_conn *ct,
 	info->sig_port[!dir] = 0;
 
 	/* Give it 30 seconds for UCF or URJ */
-	nf_ct_refresh(ct, skb, 30 * HZ);
+	nf_ct_refresh(ct, 30 * HZ);
 
 	return 0;
 }
diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index d0eac27f6ba0..ca748f8dbff1 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -1553,7 +1553,7 @@ static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
 	if (dataoff >= skb->len)
 		return NF_ACCEPT;
 
-	nf_ct_refresh(ct, skb, sip_timeout * HZ);
+	nf_ct_refresh(ct, sip_timeout * HZ);
 
 	if (unlikely(skb_linearize(skb)))
 		return NF_DROP;
@@ -1624,7 +1624,7 @@ static int sip_help_udp(struct sk_buff *skb, unsigned int protoff,
 	if (dataoff >= skb->len)
 		return NF_ACCEPT;
 
-	nf_ct_refresh(ct, skb, sip_timeout * HZ);
+	nf_ct_refresh(ct, sip_timeout * HZ);
 
 	if (unlikely(skb_linearize(skb)))
 		return NF_DROP;
diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c
index 67a41cd2baaf..2e59aba681a1 100644
--- a/net/netfilter/nft_ct.c
+++ b/net/netfilter/nft_ct.c
@@ -929,7 +929,7 @@ static void nft_ct_timeout_obj_eval(struct nft_object *obj,
 	 */
 	values = nf_ct_timeout_data(timeout);
 	if (values)
-		nf_ct_refresh(ct, pkt->skb, values[0]);
+		nf_ct_refresh(ct, values[0]);
 }
 
 static int nft_ct_timeout_obj_init(const struct nft_ctx *ctx,
-- 
cgit v1.2.3


From 03428ca5cee9f0792edc996c06ce4514816af1fb Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Tue, 14 Jan 2025 00:50:36 +0100
Subject: netfilter: conntrack: rework offload nf_conn timeout extension logic

Offload nf_conn entries may not see traffic for a very long time.

To prevent incorrect 'ct is stale' checks during nf_conntrack table
lookup, the gc worker extends the timeout nf_conn entries marked for
offload to a large value.

The existing logic suffers from a few problems.

Garbage collection runs without locks, its unlikely but possible
that @ct is removed right after the 'offload' bit test.

In that case, the timeout of a new/reallocated nf_conn entry will
be increased.

Prevent this by obtaining a reference count on the ct object and
re-check of the confirmed and offload bits.

If those are not set, the ct is being removed, skip the timeout
extension in this case.

Parallel teardown is also problematic:
 cpu1                                cpu2
 gc_worker
                                     calls flow_offload_teardown()
 tests OFFLOAD bit, set
                                     clear OFFLOAD bit
                                     ct->timeout is repaired (e.g. set to timeout[UDP_CT_REPLIED])
 nf_ct_offload_timeout() called
 expire value is fetched
 <INTERRUPT>
-> NF_CT_DAY timeout for flow that isn't offloaded
(and might not see any further packets).

Use cmpxchg: if ct->timeout was repaired after the 2nd 'offload bit' test
passed, then ct->timeout will only be updated of ct->timeout was not
altered in between.

As we already have a gc worker for flowtable entries, ct->timeout repair
can be handled from the flowtable gc worker.

This avoids having flowtable specific logic in the conntrack core
and avoids checking entries that were never offloaded.

This allows to remove the nf_ct_offload_timeout helper.
Its safe to use in the add case, but not on teardown.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/net/netfilter/nf_conntrack.h |  10 ----
 net/netfilter/nf_conntrack_core.c    |   6 --
 net/netfilter/nf_flow_table_core.c   | 105 ++++++++++++++++++++++++++++++++++-
 3 files changed, 103 insertions(+), 18 deletions(-)

(limited to 'include/net')

diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index 3cbf29dd0b71..3f02a45773e8 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -312,16 +312,6 @@ static inline bool nf_ct_should_gc(const struct nf_conn *ct)
 
 #define	NF_CT_DAY	(86400 * HZ)
 
-/* Set an arbitrary timeout large enough not to ever expire, this save
- * us a check for the IPS_OFFLOAD_BIT from the packet path via
- * nf_ct_is_expired().
- */
-static inline void nf_ct_offload_timeout(struct nf_conn *ct)
-{
-	if (nf_ct_expires(ct) < NF_CT_DAY / 2)
-		WRITE_ONCE(ct->timeout, nfct_time_stamp + NF_CT_DAY);
-}
-
 struct kernel_param;
 
 int nf_conntrack_set_hashsize(const char *val, const struct kernel_param *kp);
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 0149d482adaa..7f8b245e287a 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1544,12 +1544,6 @@ static void gc_worker(struct work_struct *work)
 
 			tmp = nf_ct_tuplehash_to_ctrack(h);
 
-			if (test_bit(IPS_OFFLOAD_BIT, &tmp->status)) {
-				nf_ct_offload_timeout(tmp);
-				if (!nf_conntrack_max95)
-					continue;
-			}
-
 			if (expired_count > GC_SCAN_EXPIRED_MAX) {
 				rcu_read_unlock();
 
diff --git a/net/netfilter/nf_flow_table_core.c b/net/netfilter/nf_flow_table_core.c
index bdde469bbbd1..35396f568ecd 100644
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -304,7 +304,7 @@ int flow_offload_add(struct nf_flowtable *flow_table, struct flow_offload *flow)
 		return err;
 	}
 
-	nf_ct_offload_timeout(flow->ct);
+	nf_ct_refresh(flow->ct, NF_CT_DAY);
 
 	if (nf_flowtable_hw_offload(flow_table)) {
 		__set_bit(NF_FLOW_HW, &flow->flags);
@@ -424,15 +424,116 @@ static bool nf_flow_custom_gc(struct nf_flowtable *flow_table,
 	return flow_table->type->gc && flow_table->type->gc(flow);
 }
 
+/**
+ * nf_flow_table_tcp_timeout() - new timeout of offloaded tcp entry
+ * @ct:		Flowtable offloaded tcp ct
+ *
+ * Return: number of seconds when ct entry should expire.
+ */
+static u32 nf_flow_table_tcp_timeout(const struct nf_conn *ct)
+{
+	u8 state = READ_ONCE(ct->proto.tcp.state);
+
+	switch (state) {
+	case TCP_CONNTRACK_SYN_SENT:
+	case TCP_CONNTRACK_SYN_RECV:
+		return 0;
+	case TCP_CONNTRACK_ESTABLISHED:
+		return NF_CT_DAY;
+	case TCP_CONNTRACK_FIN_WAIT:
+	case TCP_CONNTRACK_CLOSE_WAIT:
+	case TCP_CONNTRACK_LAST_ACK:
+	case TCP_CONNTRACK_TIME_WAIT:
+		return 5 * 60 * HZ;
+	case TCP_CONNTRACK_CLOSE:
+		return 0;
+	}
+
+	return 0;
+}
+
+/**
+ * nf_flow_table_extend_ct_timeout() - Extend ct timeout of offloaded conntrack entry
+ * @ct:		Flowtable offloaded ct
+ *
+ * Datapath lookups in the conntrack table will evict nf_conn entries
+ * if they have expired.
+ *
+ * Once nf_conn entries have been offloaded, nf_conntrack might not see any
+ * packets anymore.  Thus ct->timeout is no longer refreshed and ct can
+ * be evicted.
+ *
+ * To avoid the need for an additional check on the offload bit for every
+ * packet processed via nf_conntrack_in(), set an arbitrary timeout large
+ * enough not to ever expire, this save us a check for the IPS_OFFLOAD_BIT
+ * from the packet path via nf_ct_is_expired().
+ */
+static void nf_flow_table_extend_ct_timeout(struct nf_conn *ct)
+{
+	static const u32 min_timeout = 5 * 60 * HZ;
+	u32 expires = nf_ct_expires(ct);
+
+	/* normal case: large enough timeout, nothing to do. */
+	if (likely(expires >= min_timeout))
+		return;
+
+	/* must check offload bit after this, we do not hold any locks.
+	 * flowtable and ct entries could have been removed on another CPU.
+	 */
+	if (!refcount_inc_not_zero(&ct->ct_general.use))
+		return;
+
+	/* load ct->status after refcount increase */
+	smp_acquire__after_ctrl_dep();
+
+	if (nf_ct_is_confirmed(ct) &&
+	    test_bit(IPS_OFFLOAD_BIT, &ct->status)) {
+		u8 l4proto = nf_ct_protonum(ct);
+		u32 new_timeout = true;
+
+		switch (l4proto) {
+		case IPPROTO_UDP:
+			new_timeout = NF_CT_DAY;
+			break;
+		case IPPROTO_TCP:
+			new_timeout = nf_flow_table_tcp_timeout(ct);
+			break;
+		default:
+			WARN_ON_ONCE(1);
+			break;
+		}
+
+		/* Update to ct->timeout from nf_conntrack happens
+		 * without holding ct->lock.
+		 *
+		 * Use cmpxchg to ensure timeout extension doesn't
+		 * happen when we race with conntrack datapath.
+		 *
+		 * The inverse -- datapath updating ->timeout right
+		 * after this -- is fine, datapath is authoritative.
+		 */
+		if (new_timeout) {
+			new_timeout += nfct_time_stamp;
+			cmpxchg(&ct->timeout, expires, new_timeout);
+		}
+	}
+
+	nf_ct_put(ct);
+}
+
 static void nf_flow_offload_gc_step(struct nf_flowtable *flow_table,
 				    struct flow_offload *flow, void *data)
 {
+	bool teardown = test_bit(NF_FLOW_TEARDOWN, &flow->flags);
+
 	if (nf_flow_has_expired(flow) ||
 	    nf_ct_is_dying(flow->ct) ||
 	    nf_flow_custom_gc(flow_table, flow))
 		flow_offload_teardown(flow);
+	else if (!teardown)
+		nf_flow_table_extend_ct_timeout(flow->ct);
 
-	if (test_bit(NF_FLOW_TEARDOWN, &flow->flags)) {
+	if (teardown) {
 		if (test_bit(NF_FLOW_HW, &flow->flags)) {
 			if (!test_bit(NF_FLOW_HW_DYING, &flow->flags))
 				nf_flow_offload_del(flow_table, flow);
-- 
cgit v1.2.3


From fdbaf5163331342e90a2c29b87629021f4c15f0c Mon Sep 17 00:00:00 2001
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Tue, 14 Jan 2025 00:50:38 +0100
Subject: netfilter: flowtable: add CLOSING state

tcp rst/fin packet triggers an immediate teardown of the flow which
results in sending flows back to the classic forwarding path.

This behaviour was introduced by:

  da5984e51063 ("netfilter: nf_flow_table: add support for sending flows back to the slow path")
  b6f27d322a0a ("netfilter: nf_flow_table: tear down TCP flows if RST or FIN was seen")

whose goal is to expedite removal of flow entries from the hardware
table. Before these patches, the flow was released after the flow entry
timed out.

However, this approach leads to packet races when restoring the
conntrack state as well as late flow re-offload situations when the TCP
connection is ending.

This patch adds a new CLOSING state that is is entered when tcp rst/fin
packet is seen. This allows for an early removal of the flow entry from
the hardware table. But the flow entry still remains in software, so tcp
packets to shut down the flow are not sent back to slow path.

If syn packet is seen from this new CLOSING state, then this flow enters
teardown state, ct state is set to TCP_CONNTRACK_CLOSE state and packet
is sent to slow path, so this TCP reopen scenario can be handled by
conntrack. TCP_CONNTRACK_CLOSE provides a small timeout that aims at
quickly releasing this stale entry from the conntrack table.

Moreover, skip hardware re-offload from flowtable software packet if the
flow is in CLOSING state.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/net/netfilter/nf_flow_table.h |  1 +
 net/netfilter/nf_flow_table_core.c    | 70 ++++++++++++++++++++++++++---------
 net/netfilter/nf_flow_table_ip.c      |  6 ++-
 3 files changed, 58 insertions(+), 19 deletions(-)

(limited to 'include/net')

diff --git a/include/net/netfilter/nf_flow_table.h b/include/net/netfilter/nf_flow_table.h
index b63d53bb9dd6..d711642e78b5 100644
--- a/include/net/netfilter/nf_flow_table.h
+++ b/include/net/netfilter/nf_flow_table.h
@@ -163,6 +163,7 @@ struct flow_offload_tuple_rhash {
 enum nf_flow_flags {
 	NF_FLOW_SNAT,
 	NF_FLOW_DNAT,
+	NF_FLOW_CLOSING,
 	NF_FLOW_TEARDOWN,
 	NF_FLOW_HW,
 	NF_FLOW_HW_DYING,
diff --git a/net/netfilter/nf_flow_table_core.c b/net/netfilter/nf_flow_table_core.c
index 35396f568ecd..9d8361526f82 100644
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -161,11 +161,23 @@ void flow_offload_route_init(struct flow_offload *flow,
 }
 EXPORT_SYMBOL_GPL(flow_offload_route_init);
 
-static void flow_offload_fixup_tcp(struct nf_conn *ct)
+static inline bool nf_flow_has_expired(const struct flow_offload *flow)
+{
+	return nf_flow_timeout_delta(flow->timeout) <= 0;
+}
+
+static void flow_offload_fixup_tcp(struct nf_conn *ct, u8 tcp_state)
 {
 	struct ip_ct_tcp *tcp = &ct->proto.tcp;
 
 	spin_lock_bh(&ct->lock);
+	if (tcp->state != tcp_state)
+		tcp->state = tcp_state;
+
+	/* syn packet triggers the TCP reopen case from conntrack. */
+	if (tcp->state == TCP_CONNTRACK_CLOSE)
+		ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_CLOSE_INIT;
+
 	/* Conntrack state is outdated due to offload bypass.
 	 * Clear IP_CT_TCP_FLAG_MAXACK_SET, otherwise conntracks
 	 * TCP reset validation will fail.
@@ -177,36 +189,58 @@ static void flow_offload_fixup_tcp(struct nf_conn *ct)
 	spin_unlock_bh(&ct->lock);
 }
 
-static void flow_offload_fixup_ct(struct nf_conn *ct)
+static void flow_offload_fixup_ct(struct flow_offload *flow)
 {
+	struct nf_conn *ct = flow->ct;
 	struct net *net = nf_ct_net(ct);
 	int l4num = nf_ct_protonum(ct);
+	bool expired, closing = false;
+	u32 offload_timeout = 0;
 	s32 timeout;
 
 	if (l4num == IPPROTO_TCP) {
-		struct nf_tcp_net *tn = nf_tcp_pernet(net);
+		const struct nf_tcp_net *tn = nf_tcp_pernet(net);
+		u8 tcp_state;
 
-		flow_offload_fixup_tcp(ct);
+		/* Enter CLOSE state if fin/rst packet has been seen, this
+		 * allows TCP reopen from conntrack. Otherwise, pick up from
+		 * the last seen TCP state.
+		 */
+		closing = test_bit(NF_FLOW_CLOSING, &flow->flags);
+		if (closing) {
+			flow_offload_fixup_tcp(ct, TCP_CONNTRACK_CLOSE);
+			timeout = READ_ONCE(tn->timeouts[TCP_CONNTRACK_CLOSE]);
+			expired = false;
+		} else {
+			tcp_state = READ_ONCE(ct->proto.tcp.state);
+			flow_offload_fixup_tcp(ct, tcp_state);
+			timeout = READ_ONCE(tn->timeouts[tcp_state]);
+			expired = nf_flow_has_expired(flow);
+		}
+		offload_timeout = READ_ONCE(tn->offload_timeout);
 
-		timeout = tn->timeouts[ct->proto.tcp.state];
-		timeout -= tn->offload_timeout;
 	} else if (l4num == IPPROTO_UDP) {
-		struct nf_udp_net *tn = nf_udp_pernet(net);
+		const struct nf_udp_net *tn = nf_udp_pernet(net);
 		enum udp_conntrack state =
 			test_bit(IPS_SEEN_REPLY_BIT, &ct->status) ?
 			UDP_CT_REPLIED : UDP_CT_UNREPLIED;
 
-		timeout = tn->timeouts[state];
-		timeout -= tn->offload_timeout;
+		timeout = READ_ONCE(tn->timeouts[state]);
+		expired = nf_flow_has_expired(flow);
+		offload_timeout = READ_ONCE(tn->offload_timeout);
 	} else {
 		return;
 	}
 
+	if (expired)
+		timeout -= offload_timeout;
+
 	if (timeout < 0)
 		timeout = 0;
 
-	if (nf_flow_timeout_delta(READ_ONCE(ct->timeout)) > (__s32)timeout)
-		WRITE_ONCE(ct->timeout, nfct_time_stamp + timeout);
+	if (closing ||
+	    nf_flow_timeout_delta(READ_ONCE(ct->timeout)) > (__s32)timeout)
+		nf_ct_refresh(ct, timeout);
 }
 
 static void flow_offload_route_release(struct flow_offload *flow)
@@ -326,18 +360,14 @@ void flow_offload_refresh(struct nf_flowtable *flow_table,
 	else
 		return;
 
-	if (likely(!nf_flowtable_hw_offload(flow_table)))
+	if (likely(!nf_flowtable_hw_offload(flow_table)) ||
+	    test_bit(NF_FLOW_CLOSING, &flow->flags))
 		return;
 
 	nf_flow_offload_add(flow_table, flow);
 }
 EXPORT_SYMBOL_GPL(flow_offload_refresh);
 
-static inline bool nf_flow_has_expired(const struct flow_offload *flow)
-{
-	return nf_flow_timeout_delta(flow->timeout) <= 0;
-}
-
 static void flow_offload_del(struct nf_flowtable *flow_table,
 			     struct flow_offload *flow)
 {
@@ -354,7 +384,7 @@ void flow_offload_teardown(struct flow_offload *flow)
 {
 	clear_bit(IPS_OFFLOAD_BIT, &flow->ct->status);
 	set_bit(NF_FLOW_TEARDOWN, &flow->flags);
-	flow_offload_fixup_ct(flow->ct);
+	flow_offload_fixup_ct(flow);
 }
 EXPORT_SYMBOL_GPL(flow_offload_teardown);
 
@@ -542,6 +572,10 @@ static void nf_flow_offload_gc_step(struct nf_flowtable *flow_table,
 		} else {
 			flow_offload_del(flow_table, flow);
 		}
+	} else if (test_bit(NF_FLOW_CLOSING, &flow->flags) &&
+		   test_bit(NF_FLOW_HW, &flow->flags) &&
+		   !test_bit(NF_FLOW_HW_DYING, &flow->flags)) {
+		nf_flow_offload_del(flow_table, flow);
 	} else if (test_bit(NF_FLOW_HW, &flow->flags)) {
 		nf_flow_offload_stats(flow_table, flow);
 	}
diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c
index a22856106383..97c6eb8847a0 100644
--- a/net/netfilter/nf_flow_table_ip.c
+++ b/net/netfilter/nf_flow_table_ip.c
@@ -28,11 +28,15 @@ static int nf_flow_state_check(struct flow_offload *flow, int proto,
 		return 0;
 
 	tcph = (void *)(skb_network_header(skb) + thoff);
-	if (unlikely(tcph->fin || tcph->rst)) {
+	if (tcph->syn && test_bit(NF_FLOW_CLOSING, &flow->flags)) {
 		flow_offload_teardown(flow);
 		return -1;
 	}
 
+	if ((tcph->fin || tcph->rst) &&
+	    !test_bit(NF_FLOW_CLOSING, &flow->flags))
+		set_bit(NF_FLOW_CLOSING, &flow->flags);
+
 	return 0;
 }
 
-- 
cgit v1.2.3