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)
+static bool __tcp_fastopen_cookie_gen(const void *path,
+ struct tcp_fastopen_cookie *foc)
{
- __be32 path[4] = { src, dst, 0, 0 };
struct tcp_fastopen_context *ctx;
+ bool ok = false;
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);
+ crypto_cipher_encrypt_one(ctx->tfm, foc->val, path);
foc->len = TCP_FASTOPEN_COOKIE_SIZE;
+ ok = true;
}
rcu_read_unlock();
+ return ok;
+}
+
+/* Generate the fastopen cookie by doing aes128 encryption on both
+ * the source and destination addresses. Pad 0s for IPv4 or IPv4-mapped-IPv6
+ * addresses. For the longer IPv6 addresses use CBC-MAC.
+ *
+ * XXX (TFO) - refactor when TCP_FASTOPEN_COOKIE_SIZE != AES_BLOCK_SIZE.
+ */
+static bool tcp_fastopen_cookie_gen(struct request_sock *req,
+ struct sk_buff *syn,
+ struct tcp_fastopen_cookie *foc)
+{
+ if (req->rsk_ops->family == AF_INET) {
+ const struct iphdr *iph = ip_hdr(syn);
+
+ __be32 path[4] = { iph->saddr, iph->daddr, 0, 0 };
+ return __tcp_fastopen_cookie_gen(path, foc);
+ }
+
+#if IS_ENABLED(CONFIG_IPV6)
+ if (req->rsk_ops->family == AF_INET6) {
+ const struct ipv6hdr *ip6h = ipv6_hdr(syn);
+ struct tcp_fastopen_cookie tmp;
+
+ if (__tcp_fastopen_cookie_gen(&ip6h->saddr, &tmp)) {
+ struct in6_addr *buf = (struct in6_addr *) tmp.val;
+ int i = 4;
+
+ for (i = 0; i < 4; i++)
+ buf->s6_addr32[i] ^= ip6h->daddr.s6_addr32[i];
+ return __tcp_fastopen_cookie_gen(buf, foc);
+ }
+ }
+#endif
+ return false;
+}
+
+static bool tcp_fastopen_create_child(struct sock *sk,
+ struct sk_buff *skb,
+ struct dst_entry *dst,
+ struct request_sock *req)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
+ struct sock *child;
+
+ 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)
+ return false;
+
+ 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?) but no need to queue the skb since
+ * there is no data. How about SYN+FIN?
+ */
+ if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1) {
+ 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->syn_data_acked = 1;
+ }
+ tcp_rsk(req)->rcv_nxt = tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+ sk->sk_data_ready(sk);
+ bh_unlock_sock(child);
+ sock_put(child);
+ WARN_ON(req->sk == NULL);
+ return true;
+}
+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;
+}
+
+/* Returns true if we should perform Fast Open on the SYN. The cookie (foc)
+ * may be updated and return the client in the SYN-ACK later. E.g., Fast Open
+ * cookie request (foc->len == 0).
+ */
+bool tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
+ struct request_sock *req,
+ struct tcp_fastopen_cookie *foc,
+ struct dst_entry *dst)
+{
+ struct tcp_fastopen_cookie valid_foc = { .len = -1 };
+ bool syn_data = TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1;
+
+ if (!((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) &&
+ (syn_data || foc->len >= 0) &&
+ tcp_fastopen_queue_check(sk))) {
+ foc->len = -1;
+ return false;
+ }
+
+ if (syn_data && (sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD))
+ goto fastopen;
+
+ if (tcp_fastopen_cookie_gen(req, skb, &valid_foc) &&
+ foc->len == TCP_FASTOPEN_COOKIE_SIZE &&
+ foc->len == valid_foc.len &&
+ !memcmp(foc->val, valid_foc.val, foc->len)) {
+ /* Cookie is valid. Create a (full) child socket to accept
+ * the data in SYN before returning a SYN-ACK to ack the
+ * data. If we fail to create the socket, fall back and
+ * ack the ISN only but includes the same cookie.
+ *
+ * Note: Data-less SYN with valid cookie is allowed to send
+ * data in SYN_RECV state.
+ */
+fastopen:
+ if (tcp_fastopen_create_child(sk, skb, dst, req)) {
+ foc->len = -1;
+ NET_INC_STATS_BH(sock_net(sk),
+ LINUX_MIB_TCPFASTOPENPASSIVE);
+ return true;
+ }
+ }
+
+ NET_INC_STATS_BH(sock_net(sk), foc->len ?
+ LINUX_MIB_TCPFASTOPENPASSIVEFAIL :
+ LINUX_MIB_TCPFASTOPENCOOKIEREQD);
+ *foc = valid_foc;
+ return false;
}
+EXPORT_SYMBOL(tcp_try_fastopen);
projects / linux-2.6-block.git / blobdiff