netdev - [PATCH bpf-next] net: netfilter: add kfunc helper to update ct timeout

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Message-Id: <1327f8f5696ff2bc60400e8f3b79047914ccc837.1651595019.git.lorenzo@kernel.org>
Date:   Tue,  3 May 2022 18:29:14 +0200
From:   Lorenzo Bianconi <lorenzo@...nel.org>
To:     bpf@...r.kernel.org
Cc:     netdev@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
        andrii@...nel.org, davem@...emloft.net, kuba@...nel.org,
        pabeni@...hat.com, pablo@...filter.org, fw@...len.de,
        netfilter-devel@...r.kernel.org, lorenzo.bianconi@...hat.com,
        brouer@...hat.com, toke@...hat.com, memxor@...il.com
Subject: [PATCH bpf-next] net: netfilter: add kfunc helper to update ct timeout

Introduce bpf_ct_refresh_timeout kfunc helper in order to update time
nf_conn lifetime. Move timeout update logic in nf_ct_refresh_timeout
utility routine.

Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
---
 include/net/netfilter/nf_conntrack.h |  1 +
 net/netfilter/nf_conntrack_bpf.c     | 20 ++++++++++++++++++++
 net/netfilter/nf_conntrack_core.c    | 21 +++++++++++++--------
 3 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index 69e6c6a218be..02b7115b92d0 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -205,6 +205,7 @@ bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff,
 		       u_int16_t l3num, struct net *net,
 		       struct nf_conntrack_tuple *tuple);
 
+void nf_ct_refresh_timeout(struct nf_conn *ct, u32 extra_jiffies);
 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);
diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c
index bc4d5cd63a94..d6dcadf0e016 100644
--- a/net/netfilter/nf_conntrack_bpf.c
+++ b/net/netfilter/nf_conntrack_bpf.c
@@ -217,16 +217,36 @@ void bpf_ct_release(struct nf_conn *nfct)
 	nf_ct_put(nfct);
 }
 
+/* bpf_ct_refresh_timeout - Refresh nf_conn object
+ *
+ * Refresh timeout associated to the provided connection tracking entry.
+ * This must be invoked for referenced PTR_TO_BTF_ID.
+ *
+ * Parameters:
+ * @nf_conn      - Pointer to referenced nf_conn object, obtained using
+ *		   bpf_xdp_ct_lookup or bpf_skb_ct_lookup.
+ * @timeout      - delta time in msecs used to increase the ct entry lifetime.
+ */
+void bpf_ct_refresh_timeout(struct nf_conn *nfct, u32 timeout)
+{
+	if (!nfct)
+		return;
+
+	nf_ct_refresh_timeout(nfct, msecs_to_jiffies(timeout));
+}
+
 __diag_pop()
 
 BTF_SET_START(nf_ct_xdp_check_kfunc_ids)
 BTF_ID(func, bpf_xdp_ct_lookup)
 BTF_ID(func, bpf_ct_release)
+BTF_ID(func, bpf_ct_refresh_timeout);
 BTF_SET_END(nf_ct_xdp_check_kfunc_ids)
 
 BTF_SET_START(nf_ct_tc_check_kfunc_ids)
 BTF_ID(func, bpf_skb_ct_lookup)
 BTF_ID(func, bpf_ct_release)
+BTF_ID(func, bpf_ct_refresh_timeout);
 BTF_SET_END(nf_ct_tc_check_kfunc_ids)
 
 BTF_SET_START(nf_ct_acquire_kfunc_ids)
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 0164e5f522e8..f43e743728bd 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -2030,16 +2030,11 @@ void nf_conntrack_alter_reply(struct nf_conn *ct,
 }
 EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply);
 
-/* 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)
+void nf_ct_refresh_timeout(struct nf_conn *ct, u32 extra_jiffies)
 {
 	/* Only update if this is not a fixed timeout */
 	if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status))
-		goto acct;
+		return;
 
 	/* If not in hash table, timer will not be active yet */
 	if (nf_ct_is_confirmed(ct))
@@ -2047,7 +2042,17 @@ void __nf_ct_refresh_acct(struct nf_conn *ct,
 
 	if (READ_ONCE(ct->timeout) != extra_jiffies)
 		WRITE_ONCE(ct->timeout, extra_jiffies);
-acct:
+}
+
+/* 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)
+{
+	nf_ct_refresh_timeout(ct, extra_jiffies);
+
 	if (do_acct)
 		nf_ct_acct_update(ct, CTINFO2DIR(ctinfo), skb->len);
 }
-- 
2.35.1