net/ipv4/tcp_fastopen.c - kernel/msm-5.4 - Gitiles

 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/tcp.h>
 #include <linux/rcupdate.h>
 #include <linux/rculist.h>
 #include <net/inetpeer.h>
 #include <net/tcp.h>

 int sysctl_tcp_fastopen __read_mostly = TFO_CLIENT_ENABLE;

 struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;

 static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock);

 void tcp_fastopen_init_key_once(bool publish)
 {
 	static u8 key[TCP_FASTOPEN_KEY_LENGTH];

 	/* tcp_fastopen_reset_cipher publishes the new context
 	 * atomically, so we allow this race happening here.
 	 *
 	 * All call sites of tcp_fastopen_cookie_gen also check
 	 * for a valid cookie, so this is an acceptable risk.
 	 */
 	if (net_get_random_once(key, sizeof(key)) && publish)
 		tcp_fastopen_reset_cipher(key, sizeof(key));
 }

 static void tcp_fastopen_ctx_free(struct rcu_head *head)
 {
 	struct tcp_fastopen_context *ctx =
 	    container_of(head, struct tcp_fastopen_context, rcu);
 	crypto_free_cipher(ctx->tfm);
 	kfree(ctx);
 }

 int tcp_fastopen_reset_cipher(void *key, unsigned int len)
 {
 	int err;
 	struct tcp_fastopen_context *ctx, *octx;

 	ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
 		return -ENOMEM;
 	ctx->tfm = crypto_alloc_cipher("aes", 0, 0);

 	if (IS_ERR(ctx->tfm)) {
 		err = PTR_ERR(ctx->tfm);
 error:		kfree(ctx);
 		pr_err("TCP: TFO aes cipher alloc error: %d\n", err);
 		return err;
 	}
 	err = crypto_cipher_setkey(ctx->tfm, key, len);
 	if (err) {
 		pr_err("TCP: TFO cipher key error: %d\n", err);
 		crypto_free_cipher(ctx->tfm);
 		goto error;
 	}
 	memcpy(ctx->key, key, len);

 	spin_lock(&tcp_fastopen_ctx_lock);

 	octx = rcu_dereference_protected(tcp_fastopen_ctx,
 				lockdep_is_held(&tcp_fastopen_ctx_lock));
 	rcu_assign_pointer(tcp_fastopen_ctx, ctx);
 	spin_unlock(&tcp_fastopen_ctx_lock);

 	if (octx)
 		call_rcu(&octx->rcu, tcp_fastopen_ctx_free);
 	return err;
 }

 /* Computes the fastopen cookie for the IP path.
  * The path is a 128 bits long (pad with zeros for IPv4).
  *
  * The caller must check foc->len to determine if a valid cookie
  * has been generated successfully.
 */
 void tcp_fastopen_cookie_gen(__be32 src, __be32 dst,
 			     struct tcp_fastopen_cookie *foc)
 {
 	__be32 path[4] = { src, dst, 0, 0 };
 	struct tcp_fastopen_context *ctx;

 	tcp_fastopen_init_key_once(true);

 	rcu_read_lock();
 	ctx = rcu_dereference(tcp_fastopen_ctx);
 	if (ctx) {
 		crypto_cipher_encrypt_one(ctx->tfm, foc->val, (__u8 *)path);
 		foc->len = TCP_FASTOPEN_COOKIE_SIZE;
 	}
 	rcu_read_unlock();
 }

 int tcp_fastopen_create_child(struct sock *sk,
 			      struct sk_buff *skb,
 			      struct sk_buff *skb_synack,
 			      struct request_sock *req)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
 	const struct inet_request_sock *ireq = inet_rsk(req);
 	struct sock *child;
 	int err;

 	req->num_retrans = 0;
 	req->num_timeout = 0;
 	req->sk = NULL;

 	child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
 	if (child == NULL) {
 		NET_INC_STATS_BH(sock_net(sk),
 				 LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
 		kfree_skb(skb_synack);
 		return -1;
 	}
 	err = ip_build_and_send_pkt(skb_synack, sk, ireq->ir_loc_addr,
 				    ireq->ir_rmt_addr, ireq->opt);
 	err = net_xmit_eval(err);
 	if (!err)
 		tcp_rsk(req)->snt_synack = tcp_time_stamp;
 	/* XXX (TFO) - is it ok to ignore error and continue? */

 	spin_lock(&queue->fastopenq->lock);
 	queue->fastopenq->qlen++;
 	spin_unlock(&queue->fastopenq->lock);

 	/* Initialize the child socket. Have to fix some values to take
 	 * into account the child is a Fast Open socket and is created
 	 * only out of the bits carried in the SYN packet.
 	 */
 	tp = tcp_sk(child);

 	tp->fastopen_rsk = req;
 	/* Do a hold on the listner sk so that if the listener is being
 	 * closed, the child that has been accepted can live on and still
 	 * access listen_lock.
 	 */
 	sock_hold(sk);
 	tcp_rsk(req)->listener = sk;

 	/* RFC1323: The window in SYN & SYN/ACK segments is never
 	 * scaled. So correct it appropriately.
 	 */
 	tp->snd_wnd = ntohs(tcp_hdr(skb)->window);

 	/* Activate the retrans timer so that SYNACK can be retransmitted.
 	 * The request socket is not added to the SYN table of the parent
 	 * because it's been added to the accept queue directly.
 	 */
 	inet_csk_reset_xmit_timer(child, ICSK_TIME_RETRANS,
 				  TCP_TIMEOUT_INIT, TCP_RTO_MAX);

 	/* Add the child socket directly into the accept queue */
 	inet_csk_reqsk_queue_add(sk, req, child);

 	/* Now finish processing the fastopen child socket. */
 	inet_csk(child)->icsk_af_ops->rebuild_header(child);
 	tcp_init_congestion_control(child);
 	tcp_mtup_init(child);
 	tcp_init_metrics(child);
 	tcp_init_buffer_space(child);

 	/* Queue the data carried in the SYN packet. We need to first
 	 * bump skb's refcnt because the caller will attempt to free it.
 	 *
 	 * XXX (TFO) - we honor a zero-payload TFO request for now.
 	 * (Any reason not to?)
 	 */
 	if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq + 1) {
 		/* Don't queue the skb if there is no payload in SYN.
 		 * XXX (TFO) - How about SYN+FIN?
 		 */
 		tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
 	} else {
 		skb = skb_get(skb);
 		skb_dst_drop(skb);
 		__skb_pull(skb, tcp_hdr(skb)->doff * 4);
 		skb_set_owner_r(skb, child);
 		__skb_queue_tail(&child->sk_receive_queue, skb);
 		tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
 		tp->syn_data_acked = 1;
 	}
 	sk->sk_data_ready(sk);
 	bh_unlock_sock(child);
 	sock_put(child);
 	WARN_ON(req->sk == NULL);
 	return 0;
 }
 EXPORT_SYMBOL(tcp_fastopen_create_child);

 static bool tcp_fastopen_queue_check(struct sock *sk)
 {
 	struct fastopen_queue *fastopenq;

 	/* Make sure the listener has enabled fastopen, and we don't
 	 * exceed the max # of pending TFO requests allowed before trying
 	 * to validating the cookie in order to avoid burning CPU cycles
 	 * unnecessarily.
 	 *
 	 * XXX (TFO) - The implication of checking the max_qlen before
 	 * processing a cookie request is that clients can't differentiate
 	 * between qlen overflow causing Fast Open to be disabled
 	 * temporarily vs a server not supporting Fast Open at all.
 	 */
 	fastopenq = inet_csk(sk)->icsk_accept_queue.fastopenq;
 	if (fastopenq == NULL || fastopenq->max_qlen == 0)
 		return false;

 	if (fastopenq->qlen >= fastopenq->max_qlen) {
 		struct request_sock *req1;
 		spin_lock(&fastopenq->lock);
 		req1 = fastopenq->rskq_rst_head;
 		if ((req1 == NULL) || time_after(req1->expires, jiffies)) {
 			spin_unlock(&fastopenq->lock);
 			NET_INC_STATS_BH(sock_net(sk),
 					 LINUX_MIB_TCPFASTOPENLISTENOVERFLOW);
 			return false;
 		}
 		fastopenq->rskq_rst_head = req1->dl_next;
 		fastopenq->qlen--;
 		spin_unlock(&fastopenq->lock);
 		reqsk_free(req1);
 	}
 	return true;
 }

 bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
 			struct request_sock *req,
 			struct tcp_fastopen_cookie *foc,
 			struct tcp_fastopen_cookie *valid_foc)
 {
 	bool skip_cookie = false;

 	if (likely(!fastopen_cookie_present(foc))) {
 		/* See include/net/tcp.h for the meaning of these knobs */
 		if ((sysctl_tcp_fastopen & TFO_SERVER_ALWAYS) ||
 		    ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD) &&
 		    (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1)))
 			skip_cookie = true; /* no cookie to validate */
 		else
 			return false;
 	}
 	/* A FO option is present; bump the counter. */
 	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVE);

 	if ((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) == 0 ||
 	    !tcp_fastopen_queue_check(sk))
 		return false;

 	if (skip_cookie) {
 		tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
 		return true;
 	}

 	if (foc->len == TCP_FASTOPEN_COOKIE_SIZE) {
 		if ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_CHKED) == 0) {
 			tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
 						ip_hdr(skb)->daddr, valid_foc);
 			if ((valid_foc->len != TCP_FASTOPEN_COOKIE_SIZE) ||
 			    memcmp(&foc->val[0], &valid_foc->val[0],
 			    TCP_FASTOPEN_COOKIE_SIZE) != 0)
 				return false;
 			valid_foc->len = -1;
 		}
 		/* Acknowledge the data received from the peer. */
 		tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
 		return true;
 	} else if (foc->len == 0) { /* Client requesting a cookie */
 		tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
 					ip_hdr(skb)->daddr, valid_foc);
 		NET_INC_STATS_BH(sock_net(sk),
 		    LINUX_MIB_TCPFASTOPENCOOKIEREQD);
 	} else {
 		/* Client sent a cookie with wrong size. Treat it
 		 * the same as invalid and return a valid one.
 		 */
 		tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
 					ip_hdr(skb)->daddr, valid_foc);
 	}
 	return false;
 }
 EXPORT_SYMBOL(tcp_fastopen_check);
	#include <linux/err.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/list.h>
	#include <linux/tcp.h>
	#include <linux/rcupdate.h>
	#include <linux/rculist.h>
	#include <net/inetpeer.h>
	#include <net/tcp.h>

	int sysctl_tcp_fastopen __read_mostly = TFO_CLIENT_ENABLE;

	struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;

	static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock);

	void tcp_fastopen_init_key_once(bool publish)
	{
	static u8 key[TCP_FASTOPEN_KEY_LENGTH];

	/* tcp_fastopen_reset_cipher publishes the new context
	* atomically, so we allow this race happening here.
	*
	* All call sites of tcp_fastopen_cookie_gen also check
	* for a valid cookie, so this is an acceptable risk.
	*/
	if (net_get_random_once(key, sizeof(key)) && publish)
	tcp_fastopen_reset_cipher(key, sizeof(key));
	}

	static void tcp_fastopen_ctx_free(struct rcu_head *head)
	{
	struct tcp_fastopen_context *ctx =
	container_of(head, struct tcp_fastopen_context, rcu);
	crypto_free_cipher(ctx->tfm);
	kfree(ctx);
	}

	int tcp_fastopen_reset_cipher(void *key, unsigned int len)
	{
	int err;
	struct tcp_fastopen_context ctx, octx;

	ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
	if (!ctx)
	return -ENOMEM;
	ctx->tfm = crypto_alloc_cipher("aes", 0, 0);

	if (IS_ERR(ctx->tfm)) {
	err = PTR_ERR(ctx->tfm);
	error: kfree(ctx);
	pr_err("TCP: TFO aes cipher alloc error: %d\n", err);
	return err;
	}
	err = crypto_cipher_setkey(ctx->tfm, key, len);
	if (err) {
	pr_err("TCP: TFO cipher key error: %d\n", err);
	crypto_free_cipher(ctx->tfm);
	goto error;
	}
	memcpy(ctx->key, key, len);

	spin_lock(&tcp_fastopen_ctx_lock);

	octx = rcu_dereference_protected(tcp_fastopen_ctx,
	lockdep_is_held(&tcp_fastopen_ctx_lock));
	rcu_assign_pointer(tcp_fastopen_ctx, ctx);
	spin_unlock(&tcp_fastopen_ctx_lock);

	if (octx)
	call_rcu(&octx->rcu, tcp_fastopen_ctx_free);
	return err;
	}

	/* Computes the fastopen cookie for the IP path.
	* The path is a 128 bits long (pad with zeros for IPv4).
	*
	* The caller must check foc->len to determine if a valid cookie
	* has been generated successfully.
	*/
	void tcp_fastopen_cookie_gen(__be32 src, __be32 dst,
	struct tcp_fastopen_cookie *foc)
	{
	__be32 path[4] = { src, dst, 0, 0 };
	struct tcp_fastopen_context *ctx;

	tcp_fastopen_init_key_once(true);

	rcu_read_lock();
	ctx = rcu_dereference(tcp_fastopen_ctx);
	if (ctx) {
	crypto_cipher_encrypt_one(ctx->tfm, foc->val, (__u8 *)path);
	foc->len = TCP_FASTOPEN_COOKIE_SIZE;
	}
	rcu_read_unlock();
	}

	int tcp_fastopen_create_child(struct sock *sk,
	struct sk_buff *skb,
	struct sk_buff *skb_synack,
	struct request_sock *req)
	{
	struct tcp_sock *tp = tcp_sk(sk);
	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
	const struct inet_request_sock *ireq = inet_rsk(req);
	struct sock *child;
	int err;

	req->num_retrans = 0;
	req->num_timeout = 0;
	req->sk = NULL;

	child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
	if (child == NULL) {
	NET_INC_STATS_BH(sock_net(sk),
	LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
	kfree_skb(skb_synack);
	return -1;
	}
	err = ip_build_and_send_pkt(skb_synack, sk, ireq->ir_loc_addr,
	ireq->ir_rmt_addr, ireq->opt);
	err = net_xmit_eval(err);
	if (!err)
	tcp_rsk(req)->snt_synack = tcp_time_stamp;
	/* XXX (TFO) - is it ok to ignore error and continue? */

	spin_lock(&queue->fastopenq->lock);
	queue->fastopenq->qlen++;
	spin_unlock(&queue->fastopenq->lock);

	/* Initialize the child socket. Have to fix some values to take
	* into account the child is a Fast Open socket and is created
	* only out of the bits carried in the SYN packet.
	*/
	tp = tcp_sk(child);

	tp->fastopen_rsk = req;
	/* Do a hold on the listner sk so that if the listener is being
	* closed, the child that has been accepted can live on and still
	* access listen_lock.
	*/
	sock_hold(sk);
	tcp_rsk(req)->listener = sk;

	/* RFC1323: The window in SYN & SYN/ACK segments is never
	* scaled. So correct it appropriately.
	*/
	tp->snd_wnd = ntohs(tcp_hdr(skb)->window);

	/* Activate the retrans timer so that SYNACK can be retransmitted.
	* The request socket is not added to the SYN table of the parent
	* because it's been added to the accept queue directly.
	*/
	inet_csk_reset_xmit_timer(child, ICSK_TIME_RETRANS,
	TCP_TIMEOUT_INIT, TCP_RTO_MAX);

	/* Add the child socket directly into the accept queue */
	inet_csk_reqsk_queue_add(sk, req, child);

	/* Now finish processing the fastopen child socket. */
	inet_csk(child)->icsk_af_ops->rebuild_header(child);
	tcp_init_congestion_control(child);
	tcp_mtup_init(child);
	tcp_init_metrics(child);
	tcp_init_buffer_space(child);

	/* Queue the data carried in the SYN packet. We need to first
	* bump skb's refcnt because the caller will attempt to free it.
	*
	* XXX (TFO) - we honor a zero-payload TFO request for now.
	* (Any reason not to?)
	*/
	if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq + 1) {
	/* Don't queue the skb if there is no payload in SYN.
	* XXX (TFO) - How about SYN+FIN?
	*/
	tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
	} else {
	skb = skb_get(skb);
	skb_dst_drop(skb);
	__skb_pull(skb, tcp_hdr(skb)->doff * 4);
	skb_set_owner_r(skb, child);
	__skb_queue_tail(&child->sk_receive_queue, skb);
	tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
	tp->syn_data_acked = 1;
	}
	sk->sk_data_ready(sk);
	bh_unlock_sock(child);
	sock_put(child);
	WARN_ON(req->sk == NULL);
	return 0;
	}
	EXPORT_SYMBOL(tcp_fastopen_create_child);

	static bool tcp_fastopen_queue_check(struct sock *sk)
	{
	struct fastopen_queue *fastopenq;

	/* Make sure the listener has enabled fastopen, and we don't
	* exceed the max # of pending TFO requests allowed before trying
	* to validating the cookie in order to avoid burning CPU cycles
	* unnecessarily.
	*
	* XXX (TFO) - The implication of checking the max_qlen before
	* processing a cookie request is that clients can't differentiate
	* between qlen overflow causing Fast Open to be disabled
	* temporarily vs a server not supporting Fast Open at all.
	*/
	fastopenq = inet_csk(sk)->icsk_accept_queue.fastopenq;
	if (fastopenq == NULL \|\| fastopenq->max_qlen == 0)
	return false;

	if (fastopenq->qlen >= fastopenq->max_qlen) {
	struct request_sock *req1;
	spin_lock(&fastopenq->lock);
	req1 = fastopenq->rskq_rst_head;
	if ((req1 == NULL) \|\| time_after(req1->expires, jiffies)) {
	spin_unlock(&fastopenq->lock);
	NET_INC_STATS_BH(sock_net(sk),
	LINUX_MIB_TCPFASTOPENLISTENOVERFLOW);
	return false;
	}
	fastopenq->rskq_rst_head = req1->dl_next;
	fastopenq->qlen--;
	spin_unlock(&fastopenq->lock);
	reqsk_free(req1);
	}
	return true;
	}

	bool tcp_fastopen_check(struct sock sk, struct sk_buff skb,
	struct request_sock *req,
	struct tcp_fastopen_cookie *foc,
	struct tcp_fastopen_cookie *valid_foc)
	{
	bool skip_cookie = false;

	if (likely(!fastopen_cookie_present(foc))) {
	/* See include/net/tcp.h for the meaning of these knobs */
	if ((sysctl_tcp_fastopen & TFO_SERVER_ALWAYS) \|\|
	((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD) &&
	(TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1)))
	skip_cookie = true; /* no cookie to validate */
	else
	return false;
	}
	/* A FO option is present; bump the counter. */
	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVE);

	if ((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) == 0 \|\|
	!tcp_fastopen_queue_check(sk))
	return false;

	if (skip_cookie) {
	tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
	return true;
	}

	if (foc->len == TCP_FASTOPEN_COOKIE_SIZE) {
	if ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_CHKED) == 0) {
	tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
	ip_hdr(skb)->daddr, valid_foc);
	if ((valid_foc->len != TCP_FASTOPEN_COOKIE_SIZE) \|\|
	memcmp(&foc->val[0], &valid_foc->val[0],
	TCP_FASTOPEN_COOKIE_SIZE) != 0)
	return false;
	valid_foc->len = -1;
	}
	/* Acknowledge the data received from the peer. */
	tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
	return true;
	} else if (foc->len == 0) { /* Client requesting a cookie */
	tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
	ip_hdr(skb)->daddr, valid_foc);
	NET_INC_STATS_BH(sock_net(sk),
	LINUX_MIB_TCPFASTOPENCOOKIEREQD);
	} else {
	/* Client sent a cookie with wrong size. Treat it
	* the same as invalid and return a valid one.
	*/
	tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
	ip_hdr(skb)->daddr, valid_foc);
	}
	return false;
	}
	EXPORT_SYMBOL(tcp_fastopen_check);