![Yuchung Cheng](/assets/img/avatar_default.png)
Move common TFO functions that will be used by both v4 and v6 to tcp_fastopen.c. Create a helper tcp_fastopen_queue_check(). Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Daniel Lee <longinus00@gmail.com> Signed-off-by: Jerry Chu <hkchu@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
287 lines
8.3 KiB
C
287 lines
8.3 KiB
C
#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/tcp.h>
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#include <linux/rcupdate.h>
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#include <linux/rculist.h>
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#include <net/inetpeer.h>
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#include <net/tcp.h>
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int sysctl_tcp_fastopen __read_mostly = TFO_CLIENT_ENABLE;
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struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
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static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock);
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void tcp_fastopen_init_key_once(bool publish)
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{
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static u8 key[TCP_FASTOPEN_KEY_LENGTH];
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/* tcp_fastopen_reset_cipher publishes the new context
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* atomically, so we allow this race happening here.
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*
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* All call sites of tcp_fastopen_cookie_gen also check
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* for a valid cookie, so this is an acceptable risk.
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*/
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if (net_get_random_once(key, sizeof(key)) && publish)
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tcp_fastopen_reset_cipher(key, sizeof(key));
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}
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static void tcp_fastopen_ctx_free(struct rcu_head *head)
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{
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struct tcp_fastopen_context *ctx =
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container_of(head, struct tcp_fastopen_context, rcu);
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crypto_free_cipher(ctx->tfm);
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kfree(ctx);
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}
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int tcp_fastopen_reset_cipher(void *key, unsigned int len)
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{
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int err;
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struct tcp_fastopen_context *ctx, *octx;
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ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
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if (!ctx)
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return -ENOMEM;
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ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
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if (IS_ERR(ctx->tfm)) {
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err = PTR_ERR(ctx->tfm);
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error: kfree(ctx);
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pr_err("TCP: TFO aes cipher alloc error: %d\n", err);
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return err;
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}
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err = crypto_cipher_setkey(ctx->tfm, key, len);
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if (err) {
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pr_err("TCP: TFO cipher key error: %d\n", err);
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crypto_free_cipher(ctx->tfm);
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goto error;
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}
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memcpy(ctx->key, key, len);
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spin_lock(&tcp_fastopen_ctx_lock);
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octx = rcu_dereference_protected(tcp_fastopen_ctx,
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lockdep_is_held(&tcp_fastopen_ctx_lock));
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rcu_assign_pointer(tcp_fastopen_ctx, ctx);
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spin_unlock(&tcp_fastopen_ctx_lock);
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if (octx)
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call_rcu(&octx->rcu, tcp_fastopen_ctx_free);
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return err;
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}
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/* Computes the fastopen cookie for the IP path.
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* The path is a 128 bits long (pad with zeros for IPv4).
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*
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* The caller must check foc->len to determine if a valid cookie
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* has been generated successfully.
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*/
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void tcp_fastopen_cookie_gen(__be32 src, __be32 dst,
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struct tcp_fastopen_cookie *foc)
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{
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__be32 path[4] = { src, dst, 0, 0 };
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struct tcp_fastopen_context *ctx;
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tcp_fastopen_init_key_once(true);
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rcu_read_lock();
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ctx = rcu_dereference(tcp_fastopen_ctx);
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if (ctx) {
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crypto_cipher_encrypt_one(ctx->tfm, foc->val, (__u8 *)path);
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foc->len = TCP_FASTOPEN_COOKIE_SIZE;
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}
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rcu_read_unlock();
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}
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int tcp_fastopen_create_child(struct sock *sk,
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struct sk_buff *skb,
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struct sk_buff *skb_synack,
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struct request_sock *req)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
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const struct inet_request_sock *ireq = inet_rsk(req);
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struct sock *child;
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int err;
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req->num_retrans = 0;
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req->num_timeout = 0;
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req->sk = NULL;
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child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
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if (child == NULL) {
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NET_INC_STATS_BH(sock_net(sk),
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LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
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kfree_skb(skb_synack);
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return -1;
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}
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err = ip_build_and_send_pkt(skb_synack, sk, ireq->ir_loc_addr,
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ireq->ir_rmt_addr, ireq->opt);
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err = net_xmit_eval(err);
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if (!err)
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tcp_rsk(req)->snt_synack = tcp_time_stamp;
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/* XXX (TFO) - is it ok to ignore error and continue? */
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spin_lock(&queue->fastopenq->lock);
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queue->fastopenq->qlen++;
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spin_unlock(&queue->fastopenq->lock);
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/* Initialize the child socket. Have to fix some values to take
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* into account the child is a Fast Open socket and is created
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* only out of the bits carried in the SYN packet.
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*/
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tp = tcp_sk(child);
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tp->fastopen_rsk = req;
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/* Do a hold on the listner sk so that if the listener is being
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* closed, the child that has been accepted can live on and still
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* access listen_lock.
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*/
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sock_hold(sk);
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tcp_rsk(req)->listener = sk;
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/* RFC1323: The window in SYN & SYN/ACK segments is never
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* scaled. So correct it appropriately.
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*/
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tp->snd_wnd = ntohs(tcp_hdr(skb)->window);
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/* Activate the retrans timer so that SYNACK can be retransmitted.
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* The request socket is not added to the SYN table of the parent
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* because it's been added to the accept queue directly.
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*/
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inet_csk_reset_xmit_timer(child, ICSK_TIME_RETRANS,
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TCP_TIMEOUT_INIT, TCP_RTO_MAX);
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/* Add the child socket directly into the accept queue */
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inet_csk_reqsk_queue_add(sk, req, child);
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/* Now finish processing the fastopen child socket. */
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inet_csk(child)->icsk_af_ops->rebuild_header(child);
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tcp_init_congestion_control(child);
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tcp_mtup_init(child);
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tcp_init_metrics(child);
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tcp_init_buffer_space(child);
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/* Queue the data carried in the SYN packet. We need to first
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* bump skb's refcnt because the caller will attempt to free it.
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*
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* XXX (TFO) - we honor a zero-payload TFO request for now.
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* (Any reason not to?)
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*/
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if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq + 1) {
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/* Don't queue the skb if there is no payload in SYN.
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* XXX (TFO) - How about SYN+FIN?
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*/
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tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
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} else {
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skb = skb_get(skb);
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skb_dst_drop(skb);
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__skb_pull(skb, tcp_hdr(skb)->doff * 4);
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skb_set_owner_r(skb, child);
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__skb_queue_tail(&child->sk_receive_queue, skb);
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tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
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tp->syn_data_acked = 1;
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}
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sk->sk_data_ready(sk);
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bh_unlock_sock(child);
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sock_put(child);
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WARN_ON(req->sk == NULL);
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return 0;
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}
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EXPORT_SYMBOL(tcp_fastopen_create_child);
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static bool tcp_fastopen_queue_check(struct sock *sk)
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{
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struct fastopen_queue *fastopenq;
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/* Make sure the listener has enabled fastopen, and we don't
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* exceed the max # of pending TFO requests allowed before trying
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* to validating the cookie in order to avoid burning CPU cycles
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* unnecessarily.
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*
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* XXX (TFO) - The implication of checking the max_qlen before
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* processing a cookie request is that clients can't differentiate
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* between qlen overflow causing Fast Open to be disabled
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* temporarily vs a server not supporting Fast Open at all.
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*/
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fastopenq = inet_csk(sk)->icsk_accept_queue.fastopenq;
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if (fastopenq == NULL || fastopenq->max_qlen == 0)
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return false;
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if (fastopenq->qlen >= fastopenq->max_qlen) {
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struct request_sock *req1;
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spin_lock(&fastopenq->lock);
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req1 = fastopenq->rskq_rst_head;
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if ((req1 == NULL) || time_after(req1->expires, jiffies)) {
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spin_unlock(&fastopenq->lock);
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NET_INC_STATS_BH(sock_net(sk),
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LINUX_MIB_TCPFASTOPENLISTENOVERFLOW);
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return false;
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}
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fastopenq->rskq_rst_head = req1->dl_next;
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fastopenq->qlen--;
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spin_unlock(&fastopenq->lock);
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reqsk_free(req1);
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}
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return true;
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}
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bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
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struct request_sock *req,
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struct tcp_fastopen_cookie *foc,
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struct tcp_fastopen_cookie *valid_foc)
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{
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bool skip_cookie = false;
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if (likely(!fastopen_cookie_present(foc))) {
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/* See include/net/tcp.h for the meaning of these knobs */
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if ((sysctl_tcp_fastopen & TFO_SERVER_ALWAYS) ||
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((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD) &&
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(TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1)))
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skip_cookie = true; /* no cookie to validate */
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else
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return false;
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}
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/* A FO option is present; bump the counter. */
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NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVE);
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if ((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) == 0 ||
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!tcp_fastopen_queue_check(sk))
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return false;
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if (skip_cookie) {
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tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
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return true;
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}
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if (foc->len == TCP_FASTOPEN_COOKIE_SIZE) {
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if ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_CHKED) == 0) {
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tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
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ip_hdr(skb)->daddr, valid_foc);
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if ((valid_foc->len != TCP_FASTOPEN_COOKIE_SIZE) ||
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memcmp(&foc->val[0], &valid_foc->val[0],
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TCP_FASTOPEN_COOKIE_SIZE) != 0)
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return false;
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valid_foc->len = -1;
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}
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/* Acknowledge the data received from the peer. */
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tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
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return true;
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} else if (foc->len == 0) { /* Client requesting a cookie */
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tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
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ip_hdr(skb)->daddr, valid_foc);
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NET_INC_STATS_BH(sock_net(sk),
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LINUX_MIB_TCPFASTOPENCOOKIEREQD);
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} else {
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/* Client sent a cookie with wrong size. Treat it
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* the same as invalid and return a valid one.
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*/
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tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
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ip_hdr(skb)->daddr, valid_foc);
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}
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return false;
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}
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EXPORT_SYMBOL(tcp_fastopen_check);
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