![David S. Miller](/assets/img/avatar_default.png)
Files removed in 'net-next' had their license header updated in 'net'. We take the remove from 'net-next'. Signed-off-by: David S. Miller <davem@davemloft.net>
527 lines
15 KiB
C
527 lines
15 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/crypto.h>
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#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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void tcp_fastopen_init_key_once(struct net *net)
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{
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u8 key[TCP_FASTOPEN_KEY_LENGTH];
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struct tcp_fastopen_context *ctxt;
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rcu_read_lock();
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ctxt = rcu_dereference(net->ipv4.tcp_fastopen_ctx);
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if (ctxt) {
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rcu_read_unlock();
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return;
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}
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rcu_read_unlock();
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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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get_random_bytes(key, sizeof(key));
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tcp_fastopen_reset_cipher(net, NULL, 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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void tcp_fastopen_destroy_cipher(struct sock *sk)
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{
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struct tcp_fastopen_context *ctx;
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ctx = rcu_dereference_protected(
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inet_csk(sk)->icsk_accept_queue.fastopenq.ctx, 1);
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if (ctx)
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call_rcu(&ctx->rcu, tcp_fastopen_ctx_free);
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}
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void tcp_fastopen_ctx_destroy(struct net *net)
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{
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struct tcp_fastopen_context *ctxt;
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spin_lock(&net->ipv4.tcp_fastopen_ctx_lock);
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ctxt = rcu_dereference_protected(net->ipv4.tcp_fastopen_ctx,
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lockdep_is_held(&net->ipv4.tcp_fastopen_ctx_lock));
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rcu_assign_pointer(net->ipv4.tcp_fastopen_ctx, NULL);
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spin_unlock(&net->ipv4.tcp_fastopen_ctx_lock);
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if (ctxt)
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call_rcu(&ctxt->rcu, tcp_fastopen_ctx_free);
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}
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int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
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void *key, unsigned int len)
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{
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struct tcp_fastopen_context *ctx, *octx;
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struct fastopen_queue *q;
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int err;
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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(&net->ipv4.tcp_fastopen_ctx_lock);
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if (sk) {
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q = &inet_csk(sk)->icsk_accept_queue.fastopenq;
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octx = rcu_dereference_protected(q->ctx,
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lockdep_is_held(&net->ipv4.tcp_fastopen_ctx_lock));
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rcu_assign_pointer(q->ctx, ctx);
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} else {
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octx = rcu_dereference_protected(net->ipv4.tcp_fastopen_ctx,
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lockdep_is_held(&net->ipv4.tcp_fastopen_ctx_lock));
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rcu_assign_pointer(net->ipv4.tcp_fastopen_ctx, ctx);
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}
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spin_unlock(&net->ipv4.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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static bool __tcp_fastopen_cookie_gen(struct sock *sk, const void *path,
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struct tcp_fastopen_cookie *foc)
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{
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struct tcp_fastopen_context *ctx;
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bool ok = false;
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rcu_read_lock();
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ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
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if (!ctx)
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ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
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if (ctx) {
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crypto_cipher_encrypt_one(ctx->tfm, foc->val, path);
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foc->len = TCP_FASTOPEN_COOKIE_SIZE;
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ok = true;
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}
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rcu_read_unlock();
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return ok;
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}
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/* Generate the fastopen cookie by doing aes128 encryption on both
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* the source and destination addresses. Pad 0s for IPv4 or IPv4-mapped-IPv6
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* addresses. For the longer IPv6 addresses use CBC-MAC.
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*
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* XXX (TFO) - refactor when TCP_FASTOPEN_COOKIE_SIZE != AES_BLOCK_SIZE.
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*/
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static bool tcp_fastopen_cookie_gen(struct sock *sk,
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struct request_sock *req,
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struct sk_buff *syn,
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struct tcp_fastopen_cookie *foc)
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{
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if (req->rsk_ops->family == AF_INET) {
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const struct iphdr *iph = ip_hdr(syn);
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__be32 path[4] = { iph->saddr, iph->daddr, 0, 0 };
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return __tcp_fastopen_cookie_gen(sk, path, foc);
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}
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#if IS_ENABLED(CONFIG_IPV6)
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if (req->rsk_ops->family == AF_INET6) {
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const struct ipv6hdr *ip6h = ipv6_hdr(syn);
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struct tcp_fastopen_cookie tmp;
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if (__tcp_fastopen_cookie_gen(sk, &ip6h->saddr, &tmp)) {
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struct in6_addr *buf = &tmp.addr;
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int i;
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for (i = 0; i < 4; i++)
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buf->s6_addr32[i] ^= ip6h->daddr.s6_addr32[i];
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return __tcp_fastopen_cookie_gen(sk, buf, foc);
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}
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}
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#endif
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return false;
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}
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/* If an incoming SYN or SYNACK frame contains a payload and/or FIN,
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* queue this additional data / FIN.
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*/
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void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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if (TCP_SKB_CB(skb)->end_seq == tp->rcv_nxt)
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return;
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skb = skb_clone(skb, GFP_ATOMIC);
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if (!skb)
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return;
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skb_dst_drop(skb);
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/* segs_in has been initialized to 1 in tcp_create_openreq_child().
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* Hence, reset segs_in to 0 before calling tcp_segs_in()
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* to avoid double counting. Also, tcp_segs_in() expects
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* skb->len to include the tcp_hdrlen. Hence, it should
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* be called before __skb_pull().
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*/
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tp->segs_in = 0;
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tcp_segs_in(tp, skb);
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__skb_pull(skb, tcp_hdrlen(skb));
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sk_forced_mem_schedule(sk, skb->truesize);
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skb_set_owner_r(skb, sk);
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TCP_SKB_CB(skb)->seq++;
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TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_SYN;
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tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
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__skb_queue_tail(&sk->sk_receive_queue, skb);
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tp->syn_data_acked = 1;
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/* u64_stats_update_begin(&tp->syncp) not needed here,
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* as we certainly are not changing upper 32bit value (0)
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*/
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tp->bytes_received = skb->len;
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if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
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tcp_fin(sk);
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}
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static struct sock *tcp_fastopen_create_child(struct sock *sk,
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struct sk_buff *skb,
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struct request_sock *req)
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{
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struct tcp_sock *tp;
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struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
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struct sock *child;
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bool own_req;
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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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NULL, &own_req);
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if (!child)
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return NULL;
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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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tcp_rsk(req)->tfo_listener = true;
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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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tp->max_window = tp->snd_wnd;
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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 ehash
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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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refcount_set(&req->rsk_refcnt, 2);
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/* Now finish processing the fastopen child socket. */
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tcp_init_transfer(child, BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB);
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tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
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tcp_fastopen_add_skb(child, skb);
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tcp_rsk(req)->rcv_nxt = tp->rcv_nxt;
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tp->rcv_wup = tp->rcv_nxt;
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/* tcp_conn_request() is sending the SYNACK,
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* and queues the child into listener accept queue.
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*/
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return child;
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}
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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->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 || time_after(req1->rsk_timer.expires, jiffies)) {
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__NET_INC_STATS(sock_net(sk),
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LINUX_MIB_TCPFASTOPENLISTENOVERFLOW);
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spin_unlock(&fastopenq->lock);
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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_put(req1);
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}
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return true;
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}
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static bool tcp_fastopen_no_cookie(const struct sock *sk,
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const struct dst_entry *dst,
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int flag)
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{
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return (sock_net(sk)->ipv4.sysctl_tcp_fastopen & flag) ||
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tcp_sk(sk)->fastopen_no_cookie ||
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(dst && dst_metric(dst, RTAX_FASTOPEN_NO_COOKIE));
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}
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/* Returns true if we should perform Fast Open on the SYN. The cookie (foc)
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* may be updated and return the client in the SYN-ACK later. E.g., Fast Open
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* cookie request (foc->len == 0).
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*/
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struct sock *tcp_try_fastopen(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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const struct dst_entry *dst)
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{
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bool syn_data = TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1;
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int tcp_fastopen = sock_net(sk)->ipv4.sysctl_tcp_fastopen;
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struct tcp_fastopen_cookie valid_foc = { .len = -1 };
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struct sock *child;
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if (foc->len == 0) /* Client requests a cookie */
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NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENCOOKIEREQD);
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if (!((tcp_fastopen & TFO_SERVER_ENABLE) &&
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(syn_data || foc->len >= 0) &&
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tcp_fastopen_queue_check(sk))) {
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foc->len = -1;
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return NULL;
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}
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if (syn_data &&
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tcp_fastopen_no_cookie(sk, dst, TFO_SERVER_COOKIE_NOT_REQD))
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goto fastopen;
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if (foc->len >= 0 && /* Client presents or requests a cookie */
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tcp_fastopen_cookie_gen(sk, req, skb, &valid_foc) &&
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foc->len == TCP_FASTOPEN_COOKIE_SIZE &&
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foc->len == valid_foc.len &&
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!memcmp(foc->val, valid_foc.val, foc->len)) {
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/* Cookie is valid. Create a (full) child socket to accept
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* the data in SYN before returning a SYN-ACK to ack the
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* data. If we fail to create the socket, fall back and
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* ack the ISN only but includes the same cookie.
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*
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* Note: Data-less SYN with valid cookie is allowed to send
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* data in SYN_RECV state.
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*/
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fastopen:
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child = tcp_fastopen_create_child(sk, skb, req);
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if (child) {
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foc->len = -1;
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NET_INC_STATS(sock_net(sk),
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LINUX_MIB_TCPFASTOPENPASSIVE);
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return child;
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}
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NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
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} else if (foc->len > 0) /* Client presents an invalid cookie */
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NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
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valid_foc.exp = foc->exp;
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*foc = valid_foc;
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return NULL;
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}
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bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
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struct tcp_fastopen_cookie *cookie)
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{
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unsigned long last_syn_loss = 0;
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const struct dst_entry *dst;
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int syn_loss = 0;
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tcp_fastopen_cache_get(sk, mss, cookie, &syn_loss, &last_syn_loss);
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/* Recurring FO SYN losses: no cookie or data in SYN */
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if (syn_loss > 1 &&
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time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) {
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cookie->len = -1;
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return false;
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}
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/* Firewall blackhole issue check */
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if (tcp_fastopen_active_should_disable(sk)) {
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cookie->len = -1;
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return false;
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}
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dst = __sk_dst_get(sk);
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if (tcp_fastopen_no_cookie(sk, dst, TFO_CLIENT_NO_COOKIE)) {
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cookie->len = -1;
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return true;
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}
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return cookie->len > 0;
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}
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/* This function checks if we want to defer sending SYN until the first
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* write(). We defer under the following conditions:
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* 1. fastopen_connect sockopt is set
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* 2. we have a valid cookie
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* Return value: return true if we want to defer until application writes data
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* return false if we want to send out SYN immediately
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*/
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bool tcp_fastopen_defer_connect(struct sock *sk, int *err)
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{
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struct tcp_fastopen_cookie cookie = { .len = 0 };
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struct tcp_sock *tp = tcp_sk(sk);
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u16 mss;
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if (tp->fastopen_connect && !tp->fastopen_req) {
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if (tcp_fastopen_cookie_check(sk, &mss, &cookie)) {
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inet_sk(sk)->defer_connect = 1;
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return true;
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}
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/* Alloc fastopen_req in order for FO option to be included
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* in SYN
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*/
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tp->fastopen_req = kzalloc(sizeof(*tp->fastopen_req),
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sk->sk_allocation);
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if (tp->fastopen_req)
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tp->fastopen_req->cookie = cookie;
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else
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*err = -ENOBUFS;
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}
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return false;
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}
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EXPORT_SYMBOL(tcp_fastopen_defer_connect);
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/*
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* The following code block is to deal with middle box issues with TFO:
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* Middlebox firewall issues can potentially cause server's data being
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* blackholed after a successful 3WHS using TFO.
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* The proposed solution is to disable active TFO globally under the
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* following circumstances:
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* 1. client side TFO socket receives out of order FIN
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* 2. client side TFO socket receives out of order RST
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* We disable active side TFO globally for 1hr at first. Then if it
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* happens again, we disable it for 2h, then 4h, 8h, ...
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* And we reset the timeout back to 1hr when we see a successful active
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* TFO connection with data exchanges.
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*/
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/* Disable active TFO and record current jiffies and
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* tfo_active_disable_times
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*/
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void tcp_fastopen_active_disable(struct sock *sk)
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{
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struct net *net = sock_net(sk);
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atomic_inc(&net->ipv4.tfo_active_disable_times);
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net->ipv4.tfo_active_disable_stamp = jiffies;
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NET_INC_STATS(net, LINUX_MIB_TCPFASTOPENBLACKHOLE);
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}
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/* Calculate timeout for tfo active disable
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* Return true if we are still in the active TFO disable period
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* Return false if timeout already expired and we should use active TFO
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*/
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bool tcp_fastopen_active_should_disable(struct sock *sk)
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{
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unsigned int tfo_bh_timeout = sock_net(sk)->ipv4.sysctl_tcp_fastopen_blackhole_timeout;
|
|
int tfo_da_times = atomic_read(&sock_net(sk)->ipv4.tfo_active_disable_times);
|
|
unsigned long timeout;
|
|
int multiplier;
|
|
|
|
if (!tfo_da_times)
|
|
return false;
|
|
|
|
/* Limit timout to max: 2^6 * initial timeout */
|
|
multiplier = 1 << min(tfo_da_times - 1, 6);
|
|
timeout = multiplier * tfo_bh_timeout * HZ;
|
|
if (time_before(jiffies, sock_net(sk)->ipv4.tfo_active_disable_stamp + timeout))
|
|
return true;
|
|
|
|
/* Mark check bit so we can check for successful active TFO
|
|
* condition and reset tfo_active_disable_times
|
|
*/
|
|
tcp_sk(sk)->syn_fastopen_ch = 1;
|
|
return false;
|
|
}
|
|
|
|
/* Disable active TFO if FIN is the only packet in the ofo queue
|
|
* and no data is received.
|
|
* Also check if we can reset tfo_active_disable_times if data is
|
|
* received successfully on a marked active TFO sockets opened on
|
|
* a non-loopback interface
|
|
*/
|
|
void tcp_fastopen_active_disable_ofo_check(struct sock *sk)
|
|
{
|
|
struct tcp_sock *tp = tcp_sk(sk);
|
|
struct dst_entry *dst;
|
|
struct sk_buff *skb;
|
|
|
|
if (!tp->syn_fastopen)
|
|
return;
|
|
|
|
if (!tp->data_segs_in) {
|
|
skb = skb_rb_first(&tp->out_of_order_queue);
|
|
if (skb && !skb_rb_next(skb)) {
|
|
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) {
|
|
tcp_fastopen_active_disable(sk);
|
|
return;
|
|
}
|
|
}
|
|
} else if (tp->syn_fastopen_ch &&
|
|
atomic_read(&sock_net(sk)->ipv4.tfo_active_disable_times)) {
|
|
dst = sk_dst_get(sk);
|
|
if (!(dst && dst->dev && (dst->dev->flags & IFF_LOOPBACK)))
|
|
atomic_set(&sock_net(sk)->ipv4.tfo_active_disable_times, 0);
|
|
dst_release(dst);
|
|
}
|
|
}
|