[PATCH v2 net-next 0/5] tcp: listener refactor part 16

[PATCH v2 net-next 0/5] tcp: listener refactor part 16

[Eric Dumazet]

A CONFIG_PROVE_RCU=y build revealed an RCU splat I had to fix.

I added const qualifiers to various md5 methods, as I expect
to call them on behalf of request sock traffic even if
the listener socket is not locked. This seems ok, but adding
const makes the contract clearer. Note a good reduction
of code size thanks to request/establish sockets convergence.

Eric Dumazet (5):
  tcp: md5: fix rcu lockdep splat
  tcp: use C99 initializers in new_state[]
  tcp: md5: input path is run under rcu protected sections
  tcp: md5: remove request sock argument of calc_md5_hash()
  tcp: md5: get rid of tcp_v[46]_reqsk_md5_lookup()

 include/net/tcp.h     | 37 +++++++++++++++++------------------
 net/ipv4/tcp.c        | 25 ++++++++++++------------
 net/ipv4/tcp_ipv4.c   | 53 +++++++++++++++------------------------------------
 net/ipv4/tcp_output.c | 24 ++++++++++++-----------
 net/ipv6/tcp_ipv6.c   | 50 ++++++++++++++----------------------------------
 5 files changed, 72 insertions(+), 117 deletions(-)

-- 
2.2.0.rc0.207.ga3a616c

[PATCH v2 net-next 1/5] tcp: md5: fix rcu lockdep splat

[Eric Dumazet]

While timer handler effectively runs a rcu read locked section,
there is no explicit rcu_read_lock()/rcu_read_unlock() annotations
and lockdep can be confused here :

net/ipv4/tcp_ipv4.c-906-        /* caller either holds rcu_read_lock() or socket lock */
net/ipv4/tcp_ipv4.c:907:        md5sig = rcu_dereference_check(tp->md5sig_info,
net/ipv4/tcp_ipv4.c-908-                                       sock_owned_by_user(sk) ||
net/ipv4/tcp_ipv4.c-909-                                       lockdep_is_held(&sk->sk_lock.slock));

Let's explicitely acquire rcu_read_lock() in tcp_make_synack()

Before commit fa76ce7328b ("inet: get rid of central tcp/dccp listener
timer"), we were holding listener lock so lockdep was happy.

Fixes: fa76ce7328b ("inet: get rid of central tcp/dccp listener timer")
Signed-off-by: Eric DUmazet <edumazet@google.com>
---
 net/ipv4/tcp_output.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 18474088c3d0..5b7fad4b314c 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -601,15 +601,14 @@ static unsigned int tcp_synack_options(struct sock *sk,
 				   struct request_sock *req,
 				   unsigned int mss, struct sk_buff *skb,
 				   struct tcp_out_options *opts,
-				   struct tcp_md5sig_key **md5,
+				   const struct tcp_md5sig_key *md5,
 				   struct tcp_fastopen_cookie *foc)
 {
 	struct inet_request_sock *ireq = inet_rsk(req);
 	unsigned int remaining = MAX_TCP_OPTION_SPACE;
 
 #ifdef CONFIG_TCP_MD5SIG
-	*md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req);
-	if (*md5) {
+	if (md5) {
 		opts->options |= OPTION_MD5;
 		remaining -= TCPOLEN_MD5SIG_ALIGNED;
 
@@ -620,8 +619,6 @@ static unsigned int tcp_synack_options(struct sock *sk,
 		 */
 		ireq->tstamp_ok &= !ireq->sack_ok;
 	}
-#else
-	*md5 = NULL;
 #endif
 
 	/* We always send an MSS option. */
@@ -2913,7 +2910,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct tcphdr *th;
 	struct sk_buff *skb;
-	struct tcp_md5sig_key *md5;
+	struct tcp_md5sig_key *md5 = NULL;
 	int tcp_header_size;
 	int mss;
 
@@ -2938,7 +2935,12 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
 	else
 #endif
 	skb_mstamp_get(&skb->skb_mstamp);
-	tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, &md5,
+
+#ifdef CONFIG_TCP_MD5SIG
+	rcu_read_lock();
+	md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req);
+#endif
+	tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5,
 					     foc) + sizeof(*th);
 
 	skb_push(skb, tcp_header_size);
@@ -2969,10 +2971,10 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
 
 #ifdef CONFIG_TCP_MD5SIG
 	/* Okay, we have all we need - do the md5 hash if needed */
-	if (md5) {
+	if (md5)
 		tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location,
 					       md5, NULL, req, skb);
-	}
+	rcu_read_unlock();
 #endif
 
 	return skb;
-- 
2.2.0.rc0.207.ga3a616c

[PATCH v2 net-next 2/5] tcp: use C99 initializers in new_state[]

[Eric Dumazet]

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv4/tcp.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 62f38428279a..dbd51cefaf02 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1913,18 +1913,19 @@ EXPORT_SYMBOL_GPL(tcp_set_state);
 
 static const unsigned char new_state[16] = {
   /* current state:        new state:      action:	*/
-  /* (Invalid)		*/ TCP_CLOSE,
-  /* TCP_ESTABLISHED	*/ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
-  /* TCP_SYN_SENT	*/ TCP_CLOSE,
-  /* TCP_SYN_RECV	*/ TCP_FIN_WAIT1 | TCP_ACTION_FIN,
-  /* TCP_FIN_WAIT1	*/ TCP_FIN_WAIT1,
-  /* TCP_FIN_WAIT2	*/ TCP_FIN_WAIT2,
-  /* TCP_TIME_WAIT	*/ TCP_CLOSE,
-  /* TCP_CLOSE		*/ TCP_CLOSE,
-  /* TCP_CLOSE_WAIT	*/ TCP_LAST_ACK  | TCP_ACTION_FIN,
-  /* TCP_LAST_ACK	*/ TCP_LAST_ACK,
-  /* TCP_LISTEN		*/ TCP_CLOSE,
-  /* TCP_CLOSING	*/ TCP_CLOSING,
+  [0 /* (Invalid) */]	= TCP_CLOSE,
+  [TCP_ESTABLISHED]	= TCP_FIN_WAIT1 | TCP_ACTION_FIN,
+  [TCP_SYN_SENT]	= TCP_CLOSE,
+  [TCP_SYN_RECV]	= TCP_FIN_WAIT1 | TCP_ACTION_FIN,
+  [TCP_FIN_WAIT1]	= TCP_FIN_WAIT1,
+  [TCP_FIN_WAIT2]	= TCP_FIN_WAIT2,
+  [TCP_TIME_WAIT]	= TCP_CLOSE,
+  [TCP_CLOSE]		= TCP_CLOSE,
+  [TCP_CLOSE_WAIT]	= TCP_LAST_ACK  | TCP_ACTION_FIN,
+  [TCP_LAST_ACK]	= TCP_LAST_ACK,
+  [TCP_LISTEN]		= TCP_CLOSE,
+  [TCP_CLOSING]		= TCP_CLOSING,
+  [TCP_NEW_SYN_RECV]	= TCP_CLOSE,	/* should not happen ! */
 };
 
 static int tcp_close_state(struct sock *sk)
-- 
2.2.0.rc0.207.ga3a616c

[PATCH v2 net-next 3/5] tcp: md5: input path is run under rcu protected sections

[Eric Dumazet]

It is guaranteed that both tcp_v4_rcv() and tcp_v6_rcv()
run from rcu read locked sections :

ip_local_deliver_finish() and ip6_input_finish() both
use rcu_read_lock()

Also align tcp_v6_inbound_md5_hash() on tcp_v4_inbound_md5_hash()
by returning a boolean.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/ipv4/tcp_ipv4.c | 17 +++--------------
 net/ipv6/tcp_ipv6.c | 25 ++++++-------------------
 2 files changed, 9 insertions(+), 33 deletions(-)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 4e90217003e8..d339a0488f51 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1153,8 +1153,9 @@ clear_hash_noput:
 }
 EXPORT_SYMBOL(tcp_v4_md5_hash_skb);
 
-static bool __tcp_v4_inbound_md5_hash(struct sock *sk,
-				      const struct sk_buff *skb)
+/* Called with rcu_read_lock() */
+static bool tcp_v4_inbound_md5_hash(struct sock *sk,
+				    const struct sk_buff *skb)
 {
 	/*
 	 * This gets called for each TCP segment that arrives
@@ -1206,18 +1207,6 @@ static bool __tcp_v4_inbound_md5_hash(struct sock *sk,
 	}
 	return false;
 }
-
-static bool tcp_v4_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb)
-{
-	bool ret;
-
-	rcu_read_lock();
-	ret = __tcp_v4_inbound_md5_hash(sk, skb);
-	rcu_read_unlock();
-
-	return ret;
-}
-
 #endif
 
 static void tcp_v4_init_req(struct request_sock *req, struct sock *sk_listener,
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 4a4e6d30c448..078e7d0f4cd8 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -633,8 +633,7 @@ clear_hash_noput:
 	return 1;
 }
 
-static int __tcp_v6_inbound_md5_hash(struct sock *sk,
-				     const struct sk_buff *skb)
+static bool tcp_v6_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb)
 {
 	const __u8 *hash_location = NULL;
 	struct tcp_md5sig_key *hash_expected;
@@ -648,16 +647,16 @@ static int __tcp_v6_inbound_md5_hash(struct sock *sk,
 
 	/* We've parsed the options - do we have a hash? */
 	if (!hash_expected && !hash_location)
-		return 0;
+		return false;
 
 	if (hash_expected && !hash_location) {
 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
-		return 1;
+		return true;
 	}
 
 	if (!hash_expected && hash_location) {
 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMD5UNEXPECTED);
-		return 1;
+		return true;
 	}
 
 	/* check the signature */
@@ -670,22 +669,10 @@ static int __tcp_v6_inbound_md5_hash(struct sock *sk,
 				     genhash ? "failed" : "mismatch",
 				     &ip6h->saddr, ntohs(th->source),
 				     &ip6h->daddr, ntohs(th->dest));
-		return 1;
+		return true;
 	}
-	return 0;
-}
-
-static int tcp_v6_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb)
-{
-	int ret;
-
-	rcu_read_lock();
-	ret = __tcp_v6_inbound_md5_hash(sk, skb);
-	rcu_read_unlock();
-
-	return ret;
+	return false;
 }
-
 #endif
 
 static void tcp_v6_init_req(struct request_sock *req, struct sock *sk,
-- 
2.2.0.rc0.207.ga3a616c

[PATCH v2 net-next 4/5] tcp: md5: remove request sock argument of calc_md5_hash()

[Eric Dumazet]

Since request and established sockets now have same base,
there is no need to pass two pointers to tcp_v4_md5_hash_skb()
or tcp_v6_md5_hash_skb()

Also add a const qualifier to their struct tcp_md5sig_key argument.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/net/tcp.h     | 29 +++++++++++++----------------
 net/ipv4/tcp_ipv4.c   | 17 +++++++----------
 net/ipv4/tcp_output.c |  4 ++--
 net/ipv6/tcp_ipv6.c   | 15 ++++++---------
 4 files changed, 28 insertions(+), 37 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index fe60e00e1919..992be858c370 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1296,9 +1296,8 @@ struct tcp_md5sig_pool {
 };
 
 /* - functions */
-int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
-			const struct sock *sk, const struct request_sock *req,
-			const struct sk_buff *skb);
+int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
+			const struct sock *sk, const struct sk_buff *skb);
 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
 		   int family, const u8 *newkey, u8 newkeylen, gfp_t gfp);
 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
@@ -1616,14 +1615,13 @@ struct tcp_sock_af_ops {
 #ifdef CONFIG_TCP_MD5SIG
 	struct tcp_md5sig_key	*(*md5_lookup) (struct sock *sk,
 						struct sock *addr_sk);
-	int			(*calc_md5_hash) (char *location,
-						  struct tcp_md5sig_key *md5,
-						  const struct sock *sk,
-						  const struct request_sock *req,
-						  const struct sk_buff *skb);
-	int			(*md5_parse) (struct sock *sk,
-					      char __user *optval,
-					      int optlen);
+	int		(*calc_md5_hash)(char *location,
+					 const struct tcp_md5sig_key *md5,
+					 const struct sock *sk,
+					 const struct sk_buff *skb);
+	int		(*md5_parse)(struct sock *sk,
+				     char __user *optval,
+				     int optlen);
 #endif
 };
 
@@ -1632,11 +1630,10 @@ struct tcp_request_sock_ops {
 #ifdef CONFIG_TCP_MD5SIG
 	struct tcp_md5sig_key	*(*md5_lookup) (struct sock *sk,
 						struct request_sock *req);
-	int			(*calc_md5_hash) (char *location,
-						  struct tcp_md5sig_key *md5,
-						  const struct sock *sk,
-						  const struct request_sock *req,
-						  const struct sk_buff *skb);
+	int		(*calc_md5_hash) (char *location,
+					  const struct tcp_md5sig_key *md5,
+					  const struct sock *sk,
+					  const struct sk_buff *skb);
 #endif
 	void (*init_req)(struct request_sock *req, struct sock *sk,
 			 struct sk_buff *skb);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index d339a0488f51..79d5c641688c 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -648,7 +648,7 @@ static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
 		if (!key)
 			goto release_sk1;
 
-		genhash = tcp_v4_md5_hash_skb(newhash, key, NULL, NULL, skb);
+		genhash = tcp_v4_md5_hash_skb(newhash, key, NULL, skb);
 		if (genhash || memcmp(hash_location, newhash, 16) != 0)
 			goto release_sk1;
 	} else {
@@ -1102,8 +1102,8 @@ clear_hash_noput:
 	return 1;
 }
 
-int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
-			const struct sock *sk, const struct request_sock *req,
+int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
+			const struct sock *sk,
 			const struct sk_buff *skb)
 {
 	struct tcp_md5sig_pool *hp;
@@ -1111,12 +1111,9 @@ int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
 	const struct tcphdr *th = tcp_hdr(skb);
 	__be32 saddr, daddr;
 
-	if (sk) {
-		saddr = inet_sk(sk)->inet_saddr;
-		daddr = inet_sk(sk)->inet_daddr;
-	} else if (req) {
-		saddr = inet_rsk(req)->ir_loc_addr;
-		daddr = inet_rsk(req)->ir_rmt_addr;
+	if (sk) { /* valid for establish/request sockets */
+		saddr = sk->sk_rcv_saddr;
+		daddr = sk->sk_daddr;
 	} else {
 		const struct iphdr *iph = ip_hdr(skb);
 		saddr = iph->saddr;
@@ -1195,7 +1192,7 @@ static bool tcp_v4_inbound_md5_hash(struct sock *sk,
 	 */
 	genhash = tcp_v4_md5_hash_skb(newhash,
 				      hash_expected,
-				      NULL, NULL, skb);
+				      NULL, skb);
 
 	if (genhash || memcmp(hash_location, newhash, 16) != 0) {
 		net_info_ratelimited("MD5 Hash failed for (%pI4, %d)->(%pI4, %d)%s\n",
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 5b7fad4b314c..501cf9d401c3 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -986,7 +986,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 	if (md5) {
 		sk_nocaps_add(sk, NETIF_F_GSO_MASK);
 		tp->af_specific->calc_md5_hash(opts.hash_location,
-					       md5, sk, NULL, skb);
+					       md5, sk, skb);
 	}
 #endif
 
@@ -2973,7 +2973,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
 	/* Okay, we have all we need - do the md5 hash if needed */
 	if (md5)
 		tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location,
-					       md5, NULL, req, skb);
+					       md5, req_to_sk(req), skb);
 	rcu_read_unlock();
 #endif
 
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 078e7d0f4cd8..57d1c41404ec 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -582,9 +582,9 @@ clear_hash_noput:
 	return 1;
 }
 
-static int tcp_v6_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
+static int tcp_v6_md5_hash_skb(char *md5_hash,
+			       const struct tcp_md5sig_key *key,
 			       const struct sock *sk,
-			       const struct request_sock *req,
 			       const struct sk_buff *skb)
 {
 	const struct in6_addr *saddr, *daddr;
@@ -592,12 +592,9 @@ static int tcp_v6_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
 	struct hash_desc *desc;
 	const struct tcphdr *th = tcp_hdr(skb);
 
-	if (sk) {
-		saddr = &inet6_sk(sk)->saddr;
+	if (sk) { /* valid for establish/request sockets */
+		saddr = &sk->sk_v6_rcv_saddr;
 		daddr = &sk->sk_v6_daddr;
-	} else if (req) {
-		saddr = &inet_rsk(req)->ir_v6_loc_addr;
-		daddr = &inet_rsk(req)->ir_v6_rmt_addr;
 	} else {
 		const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 		saddr = &ip6h->saddr;
@@ -662,7 +659,7 @@ static bool tcp_v6_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb)
 	/* check the signature */
 	genhash = tcp_v6_md5_hash_skb(newhash,
 				      hash_expected,
-				      NULL, NULL, skb);
+				      NULL, skb);
 
 	if (genhash || memcmp(hash_location, newhash, 16) != 0) {
 		net_info_ratelimited("MD5 Hash %s for [%pI6c]:%u->[%pI6c]:%u\n",
@@ -880,7 +877,7 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
 		if (!key)
 			goto release_sk1;
 
-		genhash = tcp_v6_md5_hash_skb(newhash, key, NULL, NULL, skb);
+		genhash = tcp_v6_md5_hash_skb(newhash, key, NULL, skb);
 		if (genhash || memcmp(hash_location, newhash, 16) != 0)
 			goto release_sk1;
 	} else {
-- 
2.2.0.rc0.207.ga3a616c

[PATCH v2 net-next 5/5] tcp: md5: get rid of tcp_v[46]_reqsk_md5_lookup()

[Eric Dumazet]

With request socks convergence, we no longer need
different lookup methods. A request socket can
use generic lookup function.

Add const qualifier to 2nd tcp_v[46]_md5_lookup() parameter.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/net/tcp.h     |  8 ++++----
 net/ipv4/tcp_ipv4.c   | 19 +++++--------------
 net/ipv4/tcp_output.c |  2 +-
 net/ipv6/tcp_ipv6.c   | 10 ++--------
 4 files changed, 12 insertions(+), 27 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 992be858c370..42690daa924e 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1303,7 +1303,7 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
 		   int family);
 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
-					 struct sock *addr_sk);
+					 const struct sock *addr_sk);
 
 #ifdef CONFIG_TCP_MD5SIG
 struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
@@ -1614,7 +1614,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 struct tcp_sock_af_ops {
 #ifdef CONFIG_TCP_MD5SIG
 	struct tcp_md5sig_key	*(*md5_lookup) (struct sock *sk,
-						struct sock *addr_sk);
+						const struct sock *addr_sk);
 	int		(*calc_md5_hash)(char *location,
 					 const struct tcp_md5sig_key *md5,
 					 const struct sock *sk,
@@ -1628,8 +1628,8 @@ struct tcp_sock_af_ops {
 struct tcp_request_sock_ops {
 	u16 mss_clamp;
 #ifdef CONFIG_TCP_MD5SIG
-	struct tcp_md5sig_key	*(*md5_lookup) (struct sock *sk,
-						struct request_sock *req);
+	struct tcp_md5sig_key *(*req_md5_lookup)(struct sock *sk,
+						 const struct sock *addr_sk);
 	int		(*calc_md5_hash) (char *location,
 					  const struct tcp_md5sig_key *md5,
 					  const struct sock *sk,
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 79d5c641688c..fc8995a702a6 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -898,10 +898,10 @@ struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
 					 const union tcp_md5_addr *addr,
 					 int family)
 {
-	struct tcp_sock *tp = tcp_sk(sk);
+	const struct tcp_sock *tp = tcp_sk(sk);
 	struct tcp_md5sig_key *key;
 	unsigned int size = sizeof(struct in_addr);
-	struct tcp_md5sig_info *md5sig;
+	const struct tcp_md5sig_info *md5sig;
 
 	/* caller either holds rcu_read_lock() or socket lock */
 	md5sig = rcu_dereference_check(tp->md5sig_info,
@@ -924,24 +924,15 @@ struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
 EXPORT_SYMBOL(tcp_md5_do_lookup);
 
 struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
-					 struct sock *addr_sk)
+					 const struct sock *addr_sk)
 {
 	union tcp_md5_addr *addr;
 
-	addr = (union tcp_md5_addr *)&inet_sk(addr_sk)->inet_daddr;
+	addr = (union tcp_md5_addr *)&sk->sk_daddr;
 	return tcp_md5_do_lookup(sk, addr, AF_INET);
 }
 EXPORT_SYMBOL(tcp_v4_md5_lookup);
 
-static struct tcp_md5sig_key *tcp_v4_reqsk_md5_lookup(struct sock *sk,
-						      struct request_sock *req)
-{
-	union tcp_md5_addr *addr;
-
-	addr = (union tcp_md5_addr *)&inet_rsk(req)->ir_rmt_addr;
-	return tcp_md5_do_lookup(sk, addr, AF_INET);
-}
-
 /* This can be called on a newly created socket, from other files */
 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
 		   int family, const u8 *newkey, u8 newkeylen, gfp_t gfp)
@@ -1247,7 +1238,7 @@ struct request_sock_ops tcp_request_sock_ops __read_mostly = {
 static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
 	.mss_clamp	=	TCP_MSS_DEFAULT,
 #ifdef CONFIG_TCP_MD5SIG
-	.md5_lookup	=	tcp_v4_reqsk_md5_lookup,
+	.req_md5_lookup	=	tcp_v4_md5_lookup,
 	.calc_md5_hash	=	tcp_v4_md5_hash_skb,
 #endif
 	.init_req	=	tcp_v4_init_req,
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 501cf9d401c3..2e69b8d16e68 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2938,7 +2938,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
 
 #ifdef CONFIG_TCP_MD5SIG
 	rcu_read_lock();
-	md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req);
+	md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req));
 #endif
 	tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5,
 					     foc) + sizeof(*th);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 57d1c41404ec..a9568caf4675 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -486,17 +486,11 @@ static struct tcp_md5sig_key *tcp_v6_md5_do_lookup(struct sock *sk,
 }
 
 static struct tcp_md5sig_key *tcp_v6_md5_lookup(struct sock *sk,
-						struct sock *addr_sk)
+						const struct sock *addr_sk)
 {
 	return tcp_v6_md5_do_lookup(sk, &addr_sk->sk_v6_daddr);
 }
 
-static struct tcp_md5sig_key *tcp_v6_reqsk_md5_lookup(struct sock *sk,
-						      struct request_sock *req)
-{
-	return tcp_v6_md5_do_lookup(sk, &inet_rsk(req)->ir_v6_rmt_addr);
-}
-
 static int tcp_v6_parse_md5_keys(struct sock *sk, char __user *optval,
 				 int optlen)
 {
@@ -720,7 +714,7 @@ static const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
 	.mss_clamp	=	IPV6_MIN_MTU - sizeof(struct tcphdr) -
 				sizeof(struct ipv6hdr),
 #ifdef CONFIG_TCP_MD5SIG
-	.md5_lookup	=	tcp_v6_reqsk_md5_lookup,
+	.req_md5_lookup	=	tcp_v6_md5_lookup,
 	.calc_md5_hash	=	tcp_v6_md5_hash_skb,
 #endif
 	.init_req	=	tcp_v6_init_req,
-- 
2.2.0.rc0.207.ga3a616c

Re: [PATCH v2 net-next 0/5] tcp: listener refactor part 16

[David Miller]

From: Eric Dumazet <edumazet@google.com>
Date: Tue, 24 Mar 2015 15:58:51 -0700

> A CONFIG_PROVE_RCU=y build revealed an RCU splat I had to fix.
> 
> I added const qualifiers to various md5 methods, as I expect
> to call them on behalf of request sock traffic even if
> the listener socket is not locked. This seems ok, but adding
> const makes the contract clearer. Note a good reduction
> of code size thanks to request/establish sockets convergence.

Series applied, thanks Eric.