Merge branch 'mptcp-misc-fixes-for-v6-17-rc'

Matthieu Baerts says:

====================
mptcp: misc fixes for v6.17-rc

Here are various fixes:

- Patch 1: Better handling SKB extension allocation failures.
  A fix for v5.7.

- Patches 2, 3: Avoid resetting MPTCP limits when flushing MPTCP
  endpoints. With a validation in the selftests. Fixes for v5.7.

- Patches 4, 5, 6: Disallow '0' as ADD_ADDR retransmission timeout.
  With a preparation patch, and a validation in the selftests.
  Fixes for v5.11.

- Patches 8, 9: Fix C23 extension warnings in the selftests,
  spotted by GCC. Fixes for v6.16.
====================

Link: https://patch.msgid.link/20250815-net-mptcp-misc-fixes-6-17-rc2-v1-0-521fe9957892@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/networking/mptcp-sysctl.rst

@@ -12,6 +12,8 @@ add_addr_timeout - INTEGER (seconds)
 	resent to an MPTCP peer that has not acknowledged a previous
 	ADD_ADDR message.
 
+	Do not retransmit if set to 0.
+
 	The default value matches TCP_RTO_MAX. This is a per-namespace
 	sysctl.
 

net/mptcp/options.c

@@ -1118,7 +1118,9 @@ static bool add_addr_hmac_valid(struct mptcp_sock *msk,
 	return hmac == mp_opt->ahmac;
 }
 
-/* Return false if a subflow has been reset, else return true */
+/* Return false in case of error (or subflow has been reset),
+ * else return true.
+ */
 bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
@@ -1222,7 +1224,7 @@ bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
 
 	mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
 	if (!mpext)
-		return true;
+		return false;
 
 	memset(mpext, 0, sizeof(*mpext));
 

net/mptcp/pm.c

@@ -274,6 +274,7 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
 							      add_timer);
 	struct mptcp_sock *msk = entry->sock;
 	struct sock *sk = (struct sock *)msk;
+	unsigned int timeout;
 
 	pr_debug("msk=%p\n", msk);
 
@@ -291,6 +292,10 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
 		goto out;
 	}
 
+	timeout = mptcp_get_add_addr_timeout(sock_net(sk));
+	if (!timeout)
+		goto out;
+
 	spin_lock_bh(&msk->pm.lock);
 
 	if (!mptcp_pm_should_add_signal_addr(msk)) {
@@ -302,7 +307,7 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
 
 	if (entry->retrans_times < ADD_ADDR_RETRANS_MAX)
 		sk_reset_timer(sk, timer,
-			       jiffies + mptcp_get_add_addr_timeout(sock_net(sk)));
+			       jiffies + timeout);
 
 	spin_unlock_bh(&msk->pm.lock);
 
@@ -344,6 +349,7 @@ bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk,
 	struct mptcp_pm_add_entry *add_entry = NULL;
 	struct sock *sk = (struct sock *)msk;
 	struct net *net = sock_net(sk);
+	unsigned int timeout;
 
 	lockdep_assert_held(&msk->pm.lock);
 
@@ -353,9 +359,7 @@ bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk,
 		if (WARN_ON_ONCE(mptcp_pm_is_kernel(msk)))
 			return false;
 
-		sk_reset_timer(sk, &add_entry->add_timer,
-			       jiffies + mptcp_get_add_addr_timeout(net));
-		return true;
+		goto reset_timer;
 	}
 
 	add_entry = kmalloc(sizeof(*add_entry), GFP_ATOMIC);
@@ -369,8 +373,10 @@ bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk,
 	add_entry->retrans_times = 0;
 
 	timer_setup(&add_entry->add_timer, mptcp_pm_add_timer, 0);
-	sk_reset_timer(sk, &add_entry->add_timer,
-		       jiffies + mptcp_get_add_addr_timeout(net));
+reset_timer:
+	timeout = mptcp_get_add_addr_timeout(net);
+	if (timeout)
+		sk_reset_timer(sk, &add_entry->add_timer, jiffies + timeout);
 
 	return true;
 }

net/mptcp/pm_kernel.c

@@ -1085,7 +1085,6 @@ static void __flush_addrs(struct list_head *list)
 static void __reset_counters(struct pm_nl_pernet *pernet)
 {
 	WRITE_ONCE(pernet->add_addr_signal_max, 0);
-	WRITE_ONCE(pernet->add_addr_accept_max, 0);
 	WRITE_ONCE(pernet->local_addr_max, 0);
 	pernet->addrs = 0;
 }

tools/testing/selftests/net/mptcp/mptcp_connect.c

@@ -183,9 +183,10 @@ static void xgetaddrinfo(const char *node, const char *service,
 			 struct addrinfo *hints,
 			 struct addrinfo **res)
 {
-again:
-	int err = getaddrinfo(node, service, hints, res);
+	int err;
 
+again:
+	err = getaddrinfo(node, service, hints, res);
 	if (err) {
 		const char *errstr;
 

tools/testing/selftests/net/mptcp/mptcp_inq.c

@@ -75,9 +75,10 @@ static void xgetaddrinfo(const char *node, const char *service,
 			 struct addrinfo *hints,
 			 struct addrinfo **res)
 {
-again:
-	int err = getaddrinfo(node, service, hints, res);
+	int err;
 
+again:
+	err = getaddrinfo(node, service, hints, res);
 	if (err) {
 		const char *errstr;
 

tools/testing/selftests/net/mptcp/mptcp_join.sh

@@ -3842,6 +3842,7 @@ endpoint_tests()
 	# remove and re-add
 	if reset_with_events "delete re-add signal" &&
 	   mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then
+		ip netns exec $ns1 sysctl -q net.mptcp.add_addr_timeout=0
 		pm_nl_set_limits $ns1 0 3
 		pm_nl_set_limits $ns2 3 3
 		pm_nl_add_endpoint $ns1 10.0.2.1 id 1 flags signal

tools/testing/selftests/net/mptcp/mptcp_sockopt.c

@@ -162,9 +162,10 @@ static void xgetaddrinfo(const char *node, const char *service,
 			 struct addrinfo *hints,
 			 struct addrinfo **res)
 {
-again:
-	int err = getaddrinfo(node, service, hints, res);
+	int err;
 
+again:
+	err = getaddrinfo(node, service, hints, res);
 	if (err) {
 		const char *errstr;
 

tools/testing/selftests/net/mptcp/pm_netlink.sh

@@ -198,6 +198,7 @@ set_limits 1 9 2>/dev/null
 check "get_limits" "${default_limits}" "subflows above hard limit"
 
 set_limits 8 8
+flush_endpoint  ## to make sure it doesn't affect the limits
 check "get_limits" "$(format_limits 8 8)" "set limits"
 
 flush_endpoint