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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
cf80e0e4 | 2 | #include <linux/crypto.h> |
10467163 | 3 | #include <linux/err.h> |
2100c8d2 YC |
4 | #include <linux/init.h> |
5 | #include <linux/kernel.h> | |
10467163 JC |
6 | #include <linux/list.h> |
7 | #include <linux/tcp.h> | |
8 | #include <linux/rcupdate.h> | |
9 | #include <linux/rculist.h> | |
10 | #include <net/inetpeer.h> | |
11 | #include <net/tcp.h> | |
2100c8d2 | 12 | |
0d41cca4 | 13 | int sysctl_tcp_fastopen __read_mostly = TFO_CLIENT_ENABLE; |
10467163 JC |
14 | |
15 | struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; | |
16 | ||
17 | static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock); | |
18 | ||
222e83d2 HFS |
19 | void tcp_fastopen_init_key_once(bool publish) |
20 | { | |
21 | static u8 key[TCP_FASTOPEN_KEY_LENGTH]; | |
22 | ||
23 | /* tcp_fastopen_reset_cipher publishes the new context | |
24 | * atomically, so we allow this race happening here. | |
25 | * | |
26 | * All call sites of tcp_fastopen_cookie_gen also check | |
27 | * for a valid cookie, so this is an acceptable risk. | |
28 | */ | |
29 | if (net_get_random_once(key, sizeof(key)) && publish) | |
30 | tcp_fastopen_reset_cipher(key, sizeof(key)); | |
31 | } | |
32 | ||
10467163 JC |
33 | static void tcp_fastopen_ctx_free(struct rcu_head *head) |
34 | { | |
35 | struct tcp_fastopen_context *ctx = | |
36 | container_of(head, struct tcp_fastopen_context, rcu); | |
37 | crypto_free_cipher(ctx->tfm); | |
38 | kfree(ctx); | |
39 | } | |
40 | ||
41 | int tcp_fastopen_reset_cipher(void *key, unsigned int len) | |
42 | { | |
43 | int err; | |
44 | struct tcp_fastopen_context *ctx, *octx; | |
45 | ||
46 | ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); | |
47 | if (!ctx) | |
48 | return -ENOMEM; | |
49 | ctx->tfm = crypto_alloc_cipher("aes", 0, 0); | |
50 | ||
51 | if (IS_ERR(ctx->tfm)) { | |
52 | err = PTR_ERR(ctx->tfm); | |
53 | error: kfree(ctx); | |
54 | pr_err("TCP: TFO aes cipher alloc error: %d\n", err); | |
55 | return err; | |
56 | } | |
57 | err = crypto_cipher_setkey(ctx->tfm, key, len); | |
58 | if (err) { | |
59 | pr_err("TCP: TFO cipher key error: %d\n", err); | |
60 | crypto_free_cipher(ctx->tfm); | |
61 | goto error; | |
62 | } | |
63 | memcpy(ctx->key, key, len); | |
64 | ||
65 | spin_lock(&tcp_fastopen_ctx_lock); | |
66 | ||
67 | octx = rcu_dereference_protected(tcp_fastopen_ctx, | |
68 | lockdep_is_held(&tcp_fastopen_ctx_lock)); | |
69 | rcu_assign_pointer(tcp_fastopen_ctx, ctx); | |
70 | spin_unlock(&tcp_fastopen_ctx_lock); | |
71 | ||
72 | if (octx) | |
73 | call_rcu(&octx->rcu, tcp_fastopen_ctx_free); | |
74 | return err; | |
75 | } | |
76 | ||
3a19ce0e DL |
77 | static bool __tcp_fastopen_cookie_gen(const void *path, |
78 | struct tcp_fastopen_cookie *foc) | |
10467163 | 79 | { |
10467163 | 80 | struct tcp_fastopen_context *ctx; |
3a19ce0e | 81 | bool ok = false; |
10467163 JC |
82 | |
83 | rcu_read_lock(); | |
84 | ctx = rcu_dereference(tcp_fastopen_ctx); | |
85 | if (ctx) { | |
3a19ce0e | 86 | crypto_cipher_encrypt_one(ctx->tfm, foc->val, path); |
10467163 | 87 | foc->len = TCP_FASTOPEN_COOKIE_SIZE; |
3a19ce0e | 88 | ok = true; |
10467163 JC |
89 | } |
90 | rcu_read_unlock(); | |
3a19ce0e DL |
91 | return ok; |
92 | } | |
93 | ||
94 | /* Generate the fastopen cookie by doing aes128 encryption on both | |
95 | * the source and destination addresses. Pad 0s for IPv4 or IPv4-mapped-IPv6 | |
96 | * addresses. For the longer IPv6 addresses use CBC-MAC. | |
97 | * | |
98 | * XXX (TFO) - refactor when TCP_FASTOPEN_COOKIE_SIZE != AES_BLOCK_SIZE. | |
99 | */ | |
100 | static bool tcp_fastopen_cookie_gen(struct request_sock *req, | |
101 | struct sk_buff *syn, | |
102 | struct tcp_fastopen_cookie *foc) | |
103 | { | |
104 | if (req->rsk_ops->family == AF_INET) { | |
105 | const struct iphdr *iph = ip_hdr(syn); | |
106 | ||
107 | __be32 path[4] = { iph->saddr, iph->daddr, 0, 0 }; | |
108 | return __tcp_fastopen_cookie_gen(path, foc); | |
109 | } | |
110 | ||
111 | #if IS_ENABLED(CONFIG_IPV6) | |
112 | if (req->rsk_ops->family == AF_INET6) { | |
113 | const struct ipv6hdr *ip6h = ipv6_hdr(syn); | |
114 | struct tcp_fastopen_cookie tmp; | |
115 | ||
116 | if (__tcp_fastopen_cookie_gen(&ip6h->saddr, &tmp)) { | |
003c9410 | 117 | struct in6_addr *buf = &tmp.addr; |
41c91996 | 118 | int i; |
3a19ce0e DL |
119 | |
120 | for (i = 0; i < 4; i++) | |
121 | buf->s6_addr32[i] ^= ip6h->daddr.s6_addr32[i]; | |
122 | return __tcp_fastopen_cookie_gen(buf, foc); | |
123 | } | |
124 | } | |
125 | #endif | |
126 | return false; | |
10467163 | 127 | } |
5b7ed089 | 128 | |
61d2bcae ED |
129 | |
130 | /* If an incoming SYN or SYNACK frame contains a payload and/or FIN, | |
131 | * queue this additional data / FIN. | |
132 | */ | |
133 | void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb) | |
134 | { | |
135 | struct tcp_sock *tp = tcp_sk(sk); | |
136 | ||
137 | if (TCP_SKB_CB(skb)->end_seq == tp->rcv_nxt) | |
138 | return; | |
139 | ||
140 | skb = skb_clone(skb, GFP_ATOMIC); | |
141 | if (!skb) | |
142 | return; | |
143 | ||
144 | skb_dst_drop(skb); | |
a44d6eac MKL |
145 | /* segs_in has been initialized to 1 in tcp_create_openreq_child(). |
146 | * Hence, reset segs_in to 0 before calling tcp_segs_in() | |
147 | * to avoid double counting. Also, tcp_segs_in() expects | |
148 | * skb->len to include the tcp_hdrlen. Hence, it should | |
149 | * be called before __skb_pull(). | |
150 | */ | |
151 | tp->segs_in = 0; | |
152 | tcp_segs_in(tp, skb); | |
61d2bcae | 153 | __skb_pull(skb, tcp_hdrlen(skb)); |
76061f63 | 154 | sk_forced_mem_schedule(sk, skb->truesize); |
61d2bcae ED |
155 | skb_set_owner_r(skb, sk); |
156 | ||
9d691539 ED |
157 | TCP_SKB_CB(skb)->seq++; |
158 | TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_SYN; | |
159 | ||
61d2bcae ED |
160 | tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq; |
161 | __skb_queue_tail(&sk->sk_receive_queue, skb); | |
162 | tp->syn_data_acked = 1; | |
163 | ||
164 | /* u64_stats_update_begin(&tp->syncp) not needed here, | |
165 | * as we certainly are not changing upper 32bit value (0) | |
166 | */ | |
167 | tp->bytes_received = skb->len; | |
e3e17b77 ED |
168 | |
169 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) | |
170 | tcp_fin(sk); | |
61d2bcae ED |
171 | } |
172 | ||
7c85af88 ED |
173 | static struct sock *tcp_fastopen_create_child(struct sock *sk, |
174 | struct sk_buff *skb, | |
7c85af88 | 175 | struct request_sock *req) |
5b7ed089 | 176 | { |
17846376 | 177 | struct tcp_sock *tp; |
5b7ed089 | 178 | struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue; |
5b7ed089 | 179 | struct sock *child; |
5e0724d0 | 180 | bool own_req; |
5b7ed089 YC |
181 | |
182 | req->num_retrans = 0; | |
183 | req->num_timeout = 0; | |
184 | req->sk = NULL; | |
185 | ||
5e0724d0 ED |
186 | child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL, |
187 | NULL, &own_req); | |
51456b29 | 188 | if (!child) |
7c85af88 | 189 | return NULL; |
5b7ed089 | 190 | |
0536fcc0 ED |
191 | spin_lock(&queue->fastopenq.lock); |
192 | queue->fastopenq.qlen++; | |
193 | spin_unlock(&queue->fastopenq.lock); | |
5b7ed089 YC |
194 | |
195 | /* Initialize the child socket. Have to fix some values to take | |
196 | * into account the child is a Fast Open socket and is created | |
197 | * only out of the bits carried in the SYN packet. | |
198 | */ | |
199 | tp = tcp_sk(child); | |
200 | ||
201 | tp->fastopen_rsk = req; | |
9439ce00 | 202 | tcp_rsk(req)->tfo_listener = true; |
5b7ed089 YC |
203 | |
204 | /* RFC1323: The window in SYN & SYN/ACK segments is never | |
205 | * scaled. So correct it appropriately. | |
206 | */ | |
207 | tp->snd_wnd = ntohs(tcp_hdr(skb)->window); | |
0dbd7ff3 | 208 | tp->max_window = tp->snd_wnd; |
5b7ed089 YC |
209 | |
210 | /* Activate the retrans timer so that SYNACK can be retransmitted. | |
ca6fb065 | 211 | * The request socket is not added to the ehash |
5b7ed089 YC |
212 | * because it's been added to the accept queue directly. |
213 | */ | |
214 | inet_csk_reset_xmit_timer(child, ICSK_TIME_RETRANS, | |
215 | TCP_TIMEOUT_INIT, TCP_RTO_MAX); | |
216 | ||
41c6d650 | 217 | refcount_set(&req->rsk_refcnt, 2); |
5b7ed089 YC |
218 | |
219 | /* Now finish processing the fastopen child socket. */ | |
220 | inet_csk(child)->icsk_af_ops->rebuild_header(child); | |
221 | tcp_init_congestion_control(child); | |
222 | tcp_mtup_init(child); | |
223 | tcp_init_metrics(child); | |
9872a4bd | 224 | tcp_call_bpf(child, BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB); |
5b7ed089 YC |
225 | tcp_init_buffer_space(child); |
226 | ||
61d2bcae ED |
227 | tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; |
228 | ||
229 | tcp_fastopen_add_skb(child, skb); | |
230 | ||
231 | tcp_rsk(req)->rcv_nxt = tp->rcv_nxt; | |
28b346cb | 232 | tp->rcv_wup = tp->rcv_nxt; |
7656d842 ED |
233 | /* tcp_conn_request() is sending the SYNACK, |
234 | * and queues the child into listener accept queue. | |
7c85af88 | 235 | */ |
7c85af88 | 236 | return child; |
5b7ed089 | 237 | } |
5b7ed089 YC |
238 | |
239 | static bool tcp_fastopen_queue_check(struct sock *sk) | |
240 | { | |
241 | struct fastopen_queue *fastopenq; | |
242 | ||
243 | /* Make sure the listener has enabled fastopen, and we don't | |
244 | * exceed the max # of pending TFO requests allowed before trying | |
245 | * to validating the cookie in order to avoid burning CPU cycles | |
246 | * unnecessarily. | |
247 | * | |
248 | * XXX (TFO) - The implication of checking the max_qlen before | |
249 | * processing a cookie request is that clients can't differentiate | |
250 | * between qlen overflow causing Fast Open to be disabled | |
251 | * temporarily vs a server not supporting Fast Open at all. | |
252 | */ | |
0536fcc0 ED |
253 | fastopenq = &inet_csk(sk)->icsk_accept_queue.fastopenq; |
254 | if (fastopenq->max_qlen == 0) | |
5b7ed089 YC |
255 | return false; |
256 | ||
257 | if (fastopenq->qlen >= fastopenq->max_qlen) { | |
258 | struct request_sock *req1; | |
259 | spin_lock(&fastopenq->lock); | |
260 | req1 = fastopenq->rskq_rst_head; | |
fa76ce73 | 261 | if (!req1 || time_after(req1->rsk_timer.expires, jiffies)) { |
02a1d6e7 ED |
262 | __NET_INC_STATS(sock_net(sk), |
263 | LINUX_MIB_TCPFASTOPENLISTENOVERFLOW); | |
c10d9310 | 264 | spin_unlock(&fastopenq->lock); |
5b7ed089 YC |
265 | return false; |
266 | } | |
267 | fastopenq->rskq_rst_head = req1->dl_next; | |
268 | fastopenq->qlen--; | |
269 | spin_unlock(&fastopenq->lock); | |
13854e5a | 270 | reqsk_put(req1); |
5b7ed089 YC |
271 | } |
272 | return true; | |
273 | } | |
274 | ||
89278c9d YC |
275 | /* Returns true if we should perform Fast Open on the SYN. The cookie (foc) |
276 | * may be updated and return the client in the SYN-ACK later. E.g., Fast Open | |
277 | * cookie request (foc->len == 0). | |
278 | */ | |
7c85af88 ED |
279 | struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, |
280 | struct request_sock *req, | |
11199369 | 281 | struct tcp_fastopen_cookie *foc) |
5b7ed089 | 282 | { |
89278c9d YC |
283 | struct tcp_fastopen_cookie valid_foc = { .len = -1 }; |
284 | bool syn_data = TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1; | |
7c85af88 | 285 | struct sock *child; |
5b7ed089 | 286 | |
531c94a9 | 287 | if (foc->len == 0) /* Client requests a cookie */ |
c10d9310 | 288 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENCOOKIEREQD); |
531c94a9 | 289 | |
89278c9d YC |
290 | if (!((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) && |
291 | (syn_data || foc->len >= 0) && | |
292 | tcp_fastopen_queue_check(sk))) { | |
293 | foc->len = -1; | |
7c85af88 | 294 | return NULL; |
5b7ed089 YC |
295 | } |
296 | ||
89278c9d YC |
297 | if (syn_data && (sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD)) |
298 | goto fastopen; | |
299 | ||
531c94a9 YC |
300 | if (foc->len >= 0 && /* Client presents or requests a cookie */ |
301 | tcp_fastopen_cookie_gen(req, skb, &valid_foc) && | |
3a19ce0e | 302 | foc->len == TCP_FASTOPEN_COOKIE_SIZE && |
89278c9d YC |
303 | foc->len == valid_foc.len && |
304 | !memcmp(foc->val, valid_foc.val, foc->len)) { | |
843f4a55 YC |
305 | /* Cookie is valid. Create a (full) child socket to accept |
306 | * the data in SYN before returning a SYN-ACK to ack the | |
307 | * data. If we fail to create the socket, fall back and | |
308 | * ack the ISN only but includes the same cookie. | |
309 | * | |
310 | * Note: Data-less SYN with valid cookie is allowed to send | |
311 | * data in SYN_RECV state. | |
312 | */ | |
89278c9d | 313 | fastopen: |
11199369 | 314 | child = tcp_fastopen_create_child(sk, skb, req); |
7c85af88 | 315 | if (child) { |
843f4a55 | 316 | foc->len = -1; |
c10d9310 ED |
317 | NET_INC_STATS(sock_net(sk), |
318 | LINUX_MIB_TCPFASTOPENPASSIVE); | |
7c85af88 | 319 | return child; |
843f4a55 | 320 | } |
c10d9310 | 321 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVEFAIL); |
531c94a9 | 322 | } else if (foc->len > 0) /* Client presents an invalid cookie */ |
c10d9310 | 323 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVEFAIL); |
89278c9d | 324 | |
7f9b838b | 325 | valid_foc.exp = foc->exp; |
89278c9d | 326 | *foc = valid_foc; |
7c85af88 | 327 | return NULL; |
5b7ed089 | 328 | } |
065263f4 WW |
329 | |
330 | bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, | |
331 | struct tcp_fastopen_cookie *cookie) | |
332 | { | |
333 | unsigned long last_syn_loss = 0; | |
334 | int syn_loss = 0; | |
335 | ||
336 | tcp_fastopen_cache_get(sk, mss, cookie, &syn_loss, &last_syn_loss); | |
337 | ||
338 | /* Recurring FO SYN losses: no cookie or data in SYN */ | |
339 | if (syn_loss > 1 && | |
340 | time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) { | |
341 | cookie->len = -1; | |
342 | return false; | |
343 | } | |
cf1ef3f0 WW |
344 | |
345 | /* Firewall blackhole issue check */ | |
346 | if (tcp_fastopen_active_should_disable(sk)) { | |
347 | cookie->len = -1; | |
348 | return false; | |
349 | } | |
350 | ||
065263f4 WW |
351 | if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) { |
352 | cookie->len = -1; | |
353 | return true; | |
354 | } | |
355 | return cookie->len > 0; | |
356 | } | |
19f6d3f3 WW |
357 | |
358 | /* This function checks if we want to defer sending SYN until the first | |
359 | * write(). We defer under the following conditions: | |
360 | * 1. fastopen_connect sockopt is set | |
361 | * 2. we have a valid cookie | |
362 | * Return value: return true if we want to defer until application writes data | |
363 | * return false if we want to send out SYN immediately | |
364 | */ | |
365 | bool tcp_fastopen_defer_connect(struct sock *sk, int *err) | |
366 | { | |
367 | struct tcp_fastopen_cookie cookie = { .len = 0 }; | |
368 | struct tcp_sock *tp = tcp_sk(sk); | |
369 | u16 mss; | |
370 | ||
371 | if (tp->fastopen_connect && !tp->fastopen_req) { | |
372 | if (tcp_fastopen_cookie_check(sk, &mss, &cookie)) { | |
373 | inet_sk(sk)->defer_connect = 1; | |
374 | return true; | |
375 | } | |
376 | ||
377 | /* Alloc fastopen_req in order for FO option to be included | |
378 | * in SYN | |
379 | */ | |
380 | tp->fastopen_req = kzalloc(sizeof(*tp->fastopen_req), | |
381 | sk->sk_allocation); | |
382 | if (tp->fastopen_req) | |
383 | tp->fastopen_req->cookie = cookie; | |
384 | else | |
385 | *err = -ENOBUFS; | |
386 | } | |
387 | return false; | |
388 | } | |
389 | EXPORT_SYMBOL(tcp_fastopen_defer_connect); | |
cf1ef3f0 WW |
390 | |
391 | /* | |
392 | * The following code block is to deal with middle box issues with TFO: | |
393 | * Middlebox firewall issues can potentially cause server's data being | |
394 | * blackholed after a successful 3WHS using TFO. | |
395 | * The proposed solution is to disable active TFO globally under the | |
396 | * following circumstances: | |
397 | * 1. client side TFO socket receives out of order FIN | |
398 | * 2. client side TFO socket receives out of order RST | |
399 | * We disable active side TFO globally for 1hr at first. Then if it | |
400 | * happens again, we disable it for 2h, then 4h, 8h, ... | |
401 | * And we reset the timeout back to 1hr when we see a successful active | |
402 | * TFO connection with data exchanges. | |
403 | */ | |
404 | ||
405 | /* Default to 1hr */ | |
406 | unsigned int sysctl_tcp_fastopen_blackhole_timeout __read_mostly = 60 * 60; | |
407 | static atomic_t tfo_active_disable_times __read_mostly = ATOMIC_INIT(0); | |
408 | static unsigned long tfo_active_disable_stamp __read_mostly; | |
409 | ||
410 | /* Disable active TFO and record current jiffies and | |
411 | * tfo_active_disable_times | |
412 | */ | |
46c2fa39 | 413 | void tcp_fastopen_active_disable(struct sock *sk) |
cf1ef3f0 WW |
414 | { |
415 | atomic_inc(&tfo_active_disable_times); | |
416 | tfo_active_disable_stamp = jiffies; | |
46c2fa39 | 417 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENBLACKHOLE); |
cf1ef3f0 WW |
418 | } |
419 | ||
420 | /* Reset tfo_active_disable_times to 0 */ | |
421 | void tcp_fastopen_active_timeout_reset(void) | |
422 | { | |
423 | atomic_set(&tfo_active_disable_times, 0); | |
424 | } | |
425 | ||
426 | /* Calculate timeout for tfo active disable | |
427 | * Return true if we are still in the active TFO disable period | |
428 | * Return false if timeout already expired and we should use active TFO | |
429 | */ | |
430 | bool tcp_fastopen_active_should_disable(struct sock *sk) | |
431 | { | |
432 | int tfo_da_times = atomic_read(&tfo_active_disable_times); | |
433 | int multiplier; | |
434 | unsigned long timeout; | |
435 | ||
436 | if (!tfo_da_times) | |
437 | return false; | |
438 | ||
439 | /* Limit timout to max: 2^6 * initial timeout */ | |
440 | multiplier = 1 << min(tfo_da_times - 1, 6); | |
441 | timeout = multiplier * sysctl_tcp_fastopen_blackhole_timeout * HZ; | |
442 | if (time_before(jiffies, tfo_active_disable_stamp + timeout)) | |
443 | return true; | |
444 | ||
445 | /* Mark check bit so we can check for successful active TFO | |
446 | * condition and reset tfo_active_disable_times | |
447 | */ | |
448 | tcp_sk(sk)->syn_fastopen_ch = 1; | |
449 | return false; | |
450 | } | |
451 | ||
452 | /* Disable active TFO if FIN is the only packet in the ofo queue | |
453 | * and no data is received. | |
454 | * Also check if we can reset tfo_active_disable_times if data is | |
455 | * received successfully on a marked active TFO sockets opened on | |
456 | * a non-loopback interface | |
457 | */ | |
458 | void tcp_fastopen_active_disable_ofo_check(struct sock *sk) | |
459 | { | |
460 | struct tcp_sock *tp = tcp_sk(sk); | |
461 | struct rb_node *p; | |
462 | struct sk_buff *skb; | |
463 | struct dst_entry *dst; | |
464 | ||
465 | if (!tp->syn_fastopen) | |
466 | return; | |
467 | ||
468 | if (!tp->data_segs_in) { | |
469 | p = rb_first(&tp->out_of_order_queue); | |
470 | if (p && !rb_next(p)) { | |
471 | skb = rb_entry(p, struct sk_buff, rbnode); | |
472 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) { | |
46c2fa39 | 473 | tcp_fastopen_active_disable(sk); |
cf1ef3f0 WW |
474 | return; |
475 | } | |
476 | } | |
477 | } else if (tp->syn_fastopen_ch && | |
478 | atomic_read(&tfo_active_disable_times)) { | |
479 | dst = sk_dst_get(sk); | |
480 | if (!(dst && dst->dev && (dst->dev->flags & IFF_LOOPBACK))) | |
481 | tcp_fastopen_active_timeout_reset(); | |
482 | dst_release(dst); | |
483 | } | |
484 | } |