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Date:   Thu, 12 May 2022 09:56:01 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH v2 net-next] inet: add READ_ONCE(sk->sk_bound_dev_if) in INET_MATCH()

From: Eric Dumazet <edumazet@...gle.com>

INET_MATCH() runs without holding a lock on the socket.

We probably need to annotate most reads.

This patch makes INET_MATCH() an inline function
to ease our changes.

v2:

We remove the 32bit version of it, as modern compilers
should generate the same code really, no need to
try to be smarter.

Also make 'struct net *net' the first argument.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---

Sent as a standalone patch to not spam netdev@ list.

 include/net/inet_hashtables.h | 33 +++++++++++++++------------------
 include/net/sock.h            |  3 ---
 net/ipv4/inet_hashtables.c    | 15 +++++----------
 net/ipv4/udp.c                |  3 +--
 4 files changed, 21 insertions(+), 33 deletions(-)

diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index 98e1ec1a14f0382d1f4f8e85fe5ac2a056d2d6bc..e44e410813d0f469131f54cf3372458a0340d5cf 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -295,7 +295,6 @@ static inline struct sock *inet_lookup_listener(struct net *net,
 	((__force __portpair)(((__u32)(__dport) << 16) | (__force __u32)(__be16)(__sport)))
 #endif
 
-#if (BITS_PER_LONG == 64)
 #ifdef __BIG_ENDIAN
 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
 	const __addrpair __name = (__force __addrpair) ( \
@@ -307,24 +306,22 @@ static inline struct sock *inet_lookup_listener(struct net *net,
 				   (((__force __u64)(__be32)(__daddr)) << 32) | \
 				   ((__force __u64)(__be32)(__saddr)))
 #endif /* __BIG_ENDIAN */
-#define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif, __sdif) \
-	(((__sk)->sk_portpair == (__ports))			&&	\
-	 ((__sk)->sk_addrpair == (__cookie))			&&	\
-	 (((__sk)->sk_bound_dev_if == (__dif))			||	\
-	  ((__sk)->sk_bound_dev_if == (__sdif)))		&&	\
-	 net_eq(sock_net(__sk), (__net)))
-#else /* 32-bit arch */
-#define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
-	const int __name __deprecated __attribute__((unused))
 
-#define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif, __sdif) \
-	(((__sk)->sk_portpair == (__ports))		&&		\
-	 ((__sk)->sk_daddr	== (__saddr))		&&		\
-	 ((__sk)->sk_rcv_saddr	== (__daddr))		&&		\
-	 (((__sk)->sk_bound_dev_if == (__dif))		||		\
-	  ((__sk)->sk_bound_dev_if == (__sdif)))	&&		\
-	 net_eq(sock_net(__sk), (__net)))
-#endif /* 64-bit arch */
+static inline bool INET_MATCH(struct net *net, const struct sock *sk,
+			      const __addrpair cookie, const __portpair ports,
+			      int dif, int sdif)
+{
+	int bound_dev_if;
+
+	if (!net_eq(sock_net(sk), net) ||
+	    sk->sk_portpair != ports ||
+	    sk->sk_addrpair != cookie)
+	        return false;
+
+	/* Paired with WRITE_ONCE() from sock_bindtoindex_locked() */
+	bound_dev_if = READ_ONCE(sk->sk_bound_dev_if);
+	return bound_dev_if == dif || bound_dev_if == sdif;
+}
 
 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need
  * not check it for lookups anymore, thanks Alexey. -DaveM
diff --git a/include/net/sock.h b/include/net/sock.h
index 73063c88a2499b31c1e8d25dc157d21f93b02bf5..01edfde4257d697f2a2c88ef704a3849af4e5305 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -161,9 +161,6 @@ typedef __u64 __bitwise __addrpair;
  *	for struct sock and struct inet_timewait_sock.
  */
 struct sock_common {
-	/* skc_daddr and skc_rcv_saddr must be grouped on a 8 bytes aligned
-	 * address on 64bit arches : cf INET_MATCH()
-	 */
 	union {
 		__addrpair	skc_addrpair;
 		struct {
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index a5d57fa679caa47ec31ea4b1de3c45f93be4cd13..16a8440083f7e4bebd5de51ddb41b3d886b233cd 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -410,13 +410,11 @@ struct sock *__inet_lookup_established(struct net *net,
 	sk_nulls_for_each_rcu(sk, node, &head->chain) {
 		if (sk->sk_hash != hash)
 			continue;
-		if (likely(INET_MATCH(sk, net, acookie,
-				      saddr, daddr, ports, dif, sdif))) {
+		if (likely(INET_MATCH(net, sk, acookie, ports, dif, sdif))) {
 			if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
 				goto out;
-			if (unlikely(!INET_MATCH(sk, net, acookie,
-						 saddr, daddr, ports,
-						 dif, sdif))) {
+			if (unlikely(!INET_MATCH(net, sk, acookie,
+						 ports, dif, sdif))) {
 				sock_gen_put(sk);
 				goto begin;
 			}
@@ -465,8 +463,7 @@ static int __inet_check_established(struct inet_timewait_death_row *death_row,
 		if (sk2->sk_hash != hash)
 			continue;
 
-		if (likely(INET_MATCH(sk2, net, acookie,
-					 saddr, daddr, ports, dif, sdif))) {
+		if (likely(INET_MATCH(net, sk2, acookie, ports, dif, sdif))) {
 			if (sk2->sk_state == TCP_TIME_WAIT) {
 				tw = inet_twsk(sk2);
 				if (twsk_unique(sk, sk2, twp))
@@ -532,9 +529,7 @@ static bool inet_ehash_lookup_by_sk(struct sock *sk,
 		if (esk->sk_hash != sk->sk_hash)
 			continue;
 		if (sk->sk_family == AF_INET) {
-			if (unlikely(INET_MATCH(esk, net, acookie,
-						sk->sk_daddr,
-						sk->sk_rcv_saddr,
+			if (unlikely(INET_MATCH(net, esk, acookie,
 						ports, dif, sdif))) {
 				return true;
 			}
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 9d5071c79c9599aa973b80869b7768a68a508cc2..53342ce17172722d51a5db34ca9f1d5c61fb82de 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2563,8 +2563,7 @@ static struct sock *__udp4_lib_demux_lookup(struct net *net,
 	struct sock *sk;
 
 	udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) {
-		if (INET_MATCH(sk, net, acookie, rmt_addr,
-			       loc_addr, ports, dif, sdif))
+		if (INET_MATCH(net, sk, acookie, ports, dif, sdif))
 			return sk;
 		/* Only check first socket in chain */
 		break;
-- 
2.36.0.550.gb090851708-goog

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