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Date:   Wed, 31 Jan 2018 16:07:09 -0800
From:   Christoph Paasch <cpaasch@...le.com>
To:     netdev@...r.kernel.org
Cc:     Eric Dumazet <edumazet@...gle.com>,
        Mat Martineau <mathew.j.martineau@...ux.intel.com>,
        Ivan Delalande <colona@...sta.com>
Subject: [RFC v2 07/14] tcp_md5: Don't pass along md5-key

It is much cleaner to store the key-pointer in tcp_out_options. It
allows to remove some MD5-specific code out of the function-arguments
and paves the way to adopting the TCP-option framework with TCP-MD5.

Cc: Ivan Delalande <colona@...sta.com>
Signed-off-by: Christoph Paasch <cpaasch@...le.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
---
 include/linux/tcp.h   |  1 +
 net/ipv4/tcp_output.c | 46 +++++++++++++++++++---------------------------
 2 files changed, 20 insertions(+), 27 deletions(-)

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 0958b3760cfc..ef0279194ef9 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -131,6 +131,7 @@ struct tcp_out_options {
 	__u8 *hash_location;	/* temporary pointer, overloaded */
 	__u32 tsval, tsecr;	/* need to include OPTION_TS */
 	struct tcp_fastopen_cookie *fastopen_cookie;	/* Fast open cookie */
+	struct tcp_md5sig_key *md5; /* TCP_MD5 signature key */
 };
 
 /* This is the max number of SACKS that we'll generate and process. It's safe
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 549e33a30b41..facbdf4fe9be 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -520,21 +520,18 @@ static void tcp_options_write(__be32 *ptr, struct sk_buff *skb, struct sock *sk,
  * network wire format yet.
  */
 static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
-				struct tcp_out_options *opts,
-				struct tcp_md5sig_key **md5)
+				struct tcp_out_options *opts)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	unsigned int remaining = MAX_TCP_OPTION_SPACE;
 	struct tcp_fastopen_request *fastopen = tp->fastopen_req;
 
 #ifdef CONFIG_TCP_MD5SIG
-	*md5 = tp->af_specific->md5_lookup(sk, sk);
-	if (*md5) {
+	opts->md5 = tp->af_specific->md5_lookup(sk, sk);
+	if (opts->md5) {
 		opts->options |= OPTION_MD5;
 		remaining -= TCPOLEN_MD5SIG_ALIGNED;
 	}
-#else
-	*md5 = NULL;
 #endif
 
 	/* We always get an MSS option.  The option bytes which will be seen in
@@ -549,7 +546,7 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
 	opts->mss = tcp_advertise_mss(sk);
 	remaining -= TCPOLEN_MSS_ALIGNED;
 
-	if (likely(sock_net(sk)->ipv4.sysctl_tcp_timestamps && !*md5)) {
+	if (likely(sock_net(sk)->ipv4.sysctl_tcp_timestamps && !opts->md5)) {
 		opts->options |= OPTION_TS;
 		opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset;
 		opts->tsecr = tp->rx_opt.ts_recent;
@@ -593,14 +590,13 @@ static unsigned int tcp_synack_options(const struct sock *sk,
 				       struct request_sock *req,
 				       unsigned int mss, struct sk_buff *skb,
 				       struct tcp_out_options *opts,
-				       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
-	if (md5) {
+	if (opts->md5) {
 		opts->options |= OPTION_MD5;
 		remaining -= TCPOLEN_MD5SIG_ALIGNED;
 
@@ -658,8 +654,7 @@ static unsigned int tcp_synack_options(const struct sock *sk,
  * final wire format yet.
  */
 static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb,
-					struct tcp_out_options *opts,
-					struct tcp_md5sig_key **md5)
+					struct tcp_out_options *opts)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	unsigned int size = 0;
@@ -668,13 +663,13 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb
 	opts->options = 0;
 
 #ifdef CONFIG_TCP_MD5SIG
-	*md5 = tp->af_specific->md5_lookup(sk, sk);
-	if (unlikely(*md5)) {
+	opts->md5 = tp->af_specific->md5_lookup(sk, sk);
+	if (unlikely(opts->md5)) {
 		opts->options |= OPTION_MD5;
 		size += TCPOLEN_MD5SIG_ALIGNED;
 	}
 #else
-	*md5 = NULL;
+	opts->md5 = NULL;
 #endif
 
 	if (likely(tp->rx_opt.tstamp_ok)) {
@@ -992,7 +987,6 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 	struct tcp_out_options opts;
 	unsigned int tcp_options_size, tcp_header_size;
 	struct sk_buff *oskb = NULL;
-	struct tcp_md5sig_key *md5;
 	struct tcphdr *th;
 	int err;
 
@@ -1021,10 +1015,9 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 	memset(&opts, 0, sizeof(opts));
 
 	if (unlikely(tcb->tcp_flags & TCPHDR_SYN))
-		tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5);
+		tcp_options_size = tcp_syn_options(sk, skb, &opts);
 	else
-		tcp_options_size = tcp_established_options(sk, skb, &opts,
-							   &md5);
+		tcp_options_size = tcp_established_options(sk, skb, &opts);
 	tcp_header_size = tcp_options_size + sizeof(struct tcphdr);
 
 	/* if no packet is in qdisc/device queue, then allow XPS to select
@@ -1090,10 +1083,10 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 	tcp_options_write((__be32 *)(th + 1), skb, sk, &opts);
 #ifdef CONFIG_TCP_MD5SIG
 	/* Calculate the MD5 hash, as we have all we need now */
-	if (md5) {
+	if (opts.md5) {
 		sk_nocaps_add(sk, NETIF_F_GSO_MASK);
 		tp->af_specific->calc_md5_hash(opts.hash_location,
-					       md5, sk, skb);
+					       opts.md5, sk, skb);
 	}
 #endif
 
@@ -1537,7 +1530,6 @@ unsigned int tcp_current_mss(struct sock *sk)
 	u32 mss_now;
 	unsigned int header_len;
 	struct tcp_out_options opts;
-	struct tcp_md5sig_key *md5;
 
 	mss_now = tp->mss_cache;
 
@@ -1547,7 +1539,7 @@ unsigned int tcp_current_mss(struct sock *sk)
 			mss_now = tcp_sync_mss(sk, mtu);
 	}
 
-	header_len = tcp_established_options(sk, NULL, &opts, &md5) +
+	header_len = tcp_established_options(sk, NULL, &opts) +
 		     sizeof(struct tcphdr);
 	/* The mss_cache is sized based on tp->tcp_header_len, which assumes
 	 * some common options. If this is an odd packet (because we have SACK
@@ -3128,7 +3120,6 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
 {
 	struct inet_request_sock *ireq = inet_rsk(req);
 	const struct tcp_sock *tp = tcp_sk(sk);
-	struct tcp_md5sig_key *md5 = NULL;
 	struct tcp_out_options opts;
 	struct sk_buff *skb;
 	int tcp_header_size;
@@ -3174,10 +3165,10 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
 
 #ifdef CONFIG_TCP_MD5SIG
 	rcu_read_lock();
-	md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req));
+	opts.md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req));
 #endif
 	skb_set_hash(skb, tcp_rsk(req)->txhash, PKT_HASH_TYPE_L4);
-	tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5,
+	tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts,
 					     foc) + sizeof(*th);
 
 	skb_push(skb, tcp_header_size);
@@ -3204,9 +3195,10 @@ struct sk_buff *tcp_make_synack(const 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 (opts.md5)
 		tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location,
-					       md5, req_to_sk(req), skb);
+							 opts.md5,
+							 req_to_sk(req), skb);
 	rcu_read_unlock();
 #endif
 
-- 
2.16.1

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