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hc
2024-10-09 244b2c5ca8b14627e4a17755e5922221e121c771 
 kernel/net/ipv4/tcp_fastopen.c
....@@ -30,15 +30,15 @@
3030 	 * for a valid cookie, so this is an acceptable risk.
3131 	 */
3232 	get_random_bytes(key, sizeof(key));
33
-	tcp_fastopen_reset_cipher(net, NULL, key, sizeof(key));
33
+	tcp_fastopen_reset_cipher(net, NULL, key, NULL);
3434 }
3535 
3636 static void tcp_fastopen_ctx_free(struct rcu_head *head)
3737 {
3838 	struct tcp_fastopen_context *ctx =
3939 	    container_of(head, struct tcp_fastopen_context, rcu);
40
-	crypto_free_cipher(ctx->tfm);
41
-	kfree(ctx);
40
+
41
+	kfree_sensitive(ctx);
4242 }
4343 
4444 void tcp_fastopen_destroy_cipher(struct sock *sk)
....@@ -67,31 +67,27 @@
6767 }
6868 
6969 int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
70
-			      void *key, unsigned int len)
70
+			      void *primary_key, void *backup_key)
7171 {
7272 	struct tcp_fastopen_context *ctx, *octx;
7373 	struct fastopen_queue *q;
74
-	int err;
74
+	int err = 0;
7575 
7676 	ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
77
-	if (!ctx)
78
-		return -ENOMEM;
79
-	ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
80
-
81
-	if (IS_ERR(ctx->tfm)) {
82
-		err = PTR_ERR(ctx->tfm);
83
-error:		kfree(ctx);
84
-		pr_err("TCP: TFO aes cipher alloc error: %d\n", err);
85
-		return err;
77
+	if (!ctx) {
78
+		err = -ENOMEM;
79
+		goto out;
8680 	}
87
-	err = crypto_cipher_setkey(ctx->tfm, key, len);
88
-	if (err) {
89
-		pr_err("TCP: TFO cipher key error: %d\n", err);
90
-		crypto_free_cipher(ctx->tfm);
91
-		goto error;
92
-	}
93
-	memcpy(ctx->key, key, len);
9481 
82
+	ctx->key[0].key[0] = get_unaligned_le64(primary_key);
83
+	ctx->key[0].key[1] = get_unaligned_le64(primary_key + 8);
84
+	if (backup_key) {
85
+		ctx->key[1].key[0] = get_unaligned_le64(backup_key);
86
+		ctx->key[1].key[1] = get_unaligned_le64(backup_key + 8);
87
+		ctx->num = 2;
88
+	} else {
89
+		ctx->num = 1;
90
+	}
9591 
9692 	spin_lock(&net->ipv4.tcp_fastopen_ctx_lock);
9793 	if (sk) {
....@@ -108,66 +104,81 @@
108104 
109105 	if (octx)
110106 		call_rcu(&octx->rcu, tcp_fastopen_ctx_free);
107
+out:
111108 	return err;
112109 }
113110 
114
-static bool __tcp_fastopen_cookie_gen(struct sock *sk, const void *path,
115
-				      struct tcp_fastopen_cookie *foc)
111
+int tcp_fastopen_get_cipher(struct net *net, struct inet_connection_sock *icsk,
112
+			    u64 *key)
116113 {
117114 	struct tcp_fastopen_context *ctx;
118
-	bool ok = false;
115
+	int n_keys = 0, i;
119116 
120117 	rcu_read_lock();
121
-
122
-	ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
123
-	if (!ctx)
124
-		ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
125
-
118
+	if (icsk)
119
+		ctx = rcu_dereference(icsk->icsk_accept_queue.fastopenq.ctx);
120
+	else
121
+		ctx = rcu_dereference(net->ipv4.tcp_fastopen_ctx);
126122 	if (ctx) {
127
-		crypto_cipher_encrypt_one(ctx->tfm, foc->val, path);
128
-		foc->len = TCP_FASTOPEN_COOKIE_SIZE;
129
-		ok = true;
123
+		n_keys = tcp_fastopen_context_len(ctx);
124
+		for (i = 0; i < n_keys; i++) {
125
+			put_unaligned_le64(ctx->key[i].key[0], key + (i * 2));
126
+			put_unaligned_le64(ctx->key[i].key[1], key + (i * 2) + 1);
127
+		}
130128 	}
131129 	rcu_read_unlock();
132
-	return ok;
130
+
131
+	return n_keys;
133132 }
134133 
135
-/* Generate the fastopen cookie by doing aes128 encryption on both
136
- * the source and destination addresses. Pad 0s for IPv4 or IPv4-mapped-IPv6
137
- * addresses. For the longer IPv6 addresses use CBC-MAC.
138
- *
139
- * XXX (TFO) - refactor when TCP_FASTOPEN_COOKIE_SIZE != AES_BLOCK_SIZE.
140
- */
141
-static bool tcp_fastopen_cookie_gen(struct sock *sk,
142
-				    struct request_sock *req,
143
-				    struct sk_buff *syn,
144
-				    struct tcp_fastopen_cookie *foc)
134
+static bool __tcp_fastopen_cookie_gen_cipher(struct request_sock *req,
135
+					     struct sk_buff *syn,
136
+					     const siphash_key_t *key,
137
+					     struct tcp_fastopen_cookie *foc)
145138 {
139
+	BUILD_BUG_ON(TCP_FASTOPEN_COOKIE_SIZE != sizeof(u64));
140
+
146141 	if (req->rsk_ops->family == AF_INET) {
147142 		const struct iphdr *iph = ip_hdr(syn);
148143 
149
-		__be32 path[4] = { iph->saddr, iph->daddr, 0, 0 };
150
-		return __tcp_fastopen_cookie_gen(sk, path, foc);
144
+		foc->val[0] = cpu_to_le64(siphash(&iph->saddr,
145
+					  sizeof(iph->saddr) +
146
+					  sizeof(iph->daddr),
147
+					  key));
148
+		foc->len = TCP_FASTOPEN_COOKIE_SIZE;
149
+		return true;
151150 	}
152
-
153151 #if IS_ENABLED(CONFIG_IPV6)
154152 	if (req->rsk_ops->family == AF_INET6) {
155153 		const struct ipv6hdr *ip6h = ipv6_hdr(syn);
156
-		struct tcp_fastopen_cookie tmp;
157154 
158
-		if (__tcp_fastopen_cookie_gen(sk, &ip6h->saddr, &tmp)) {
159
-			struct in6_addr *buf = &tmp.addr;
160
-			int i;
161
-
162
-			for (i = 0; i < 4; i++)
163
-				buf->s6_addr32[i] ^= ip6h->daddr.s6_addr32[i];
164
-			return __tcp_fastopen_cookie_gen(sk, buf, foc);
165
-		}
155
+		foc->val[0] = cpu_to_le64(siphash(&ip6h->saddr,
156
+					  sizeof(ip6h->saddr) +
157
+					  sizeof(ip6h->daddr),
158
+					  key));
159
+		foc->len = TCP_FASTOPEN_COOKIE_SIZE;
160
+		return true;
166161 	}
167162 #endif
168163 	return false;
169164 }
170165 
166
+/* Generate the fastopen cookie by applying SipHash to both the source and
167
+ * destination addresses.
168
+ */
169
+static void tcp_fastopen_cookie_gen(struct sock *sk,
170
+				    struct request_sock *req,
171
+				    struct sk_buff *syn,
172
+				    struct tcp_fastopen_cookie *foc)
173
+{
174
+	struct tcp_fastopen_context *ctx;
175
+
176
+	rcu_read_lock();
177
+	ctx = tcp_fastopen_get_ctx(sk);
178
+	if (ctx)
179
+		__tcp_fastopen_cookie_gen_cipher(req, syn, &ctx->key[0], foc);
180
+	rcu_read_unlock();
181
+}
171182 
172183 /* If an incoming SYN or SYNACK frame contains a payload and/or FIN,
173184  * queue this additional data / FIN.
....@@ -212,6 +223,35 @@
212223 		tcp_fin(sk);
213224 }
214225 
226
+/* returns 0 - no key match, 1 for primary, 2 for backup */
227
+static int tcp_fastopen_cookie_gen_check(struct sock *sk,
228
+					 struct request_sock *req,
229
+					 struct sk_buff *syn,
230
+					 struct tcp_fastopen_cookie *orig,
231
+					 struct tcp_fastopen_cookie *valid_foc)
232
+{
233
+	struct tcp_fastopen_cookie search_foc = { .len = -1 };
234
+	struct tcp_fastopen_cookie *foc = valid_foc;
235
+	struct tcp_fastopen_context *ctx;
236
+	int i, ret = 0;
237
+
238
+	rcu_read_lock();
239
+	ctx = tcp_fastopen_get_ctx(sk);
240
+	if (!ctx)
241
+		goto out;
242
+	for (i = 0; i < tcp_fastopen_context_len(ctx); i++) {
243
+		__tcp_fastopen_cookie_gen_cipher(req, syn, &ctx->key[i], foc);
244
+		if (tcp_fastopen_cookie_match(foc, orig)) {
245
+			ret = i + 1;
246
+			goto out;
247
+		}
248
+		foc = &search_foc;
249
+	}
250
+out:
251
+	rcu_read_unlock();
252
+	return ret;
253
+}
254
+
215255 static struct sock *tcp_fastopen_create_child(struct sock *sk,
216256 					      struct sk_buff *skb,
217257 					      struct request_sock *req)
....@@ -220,10 +260,6 @@
220260 	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
221261 	struct sock *child;
222262 	bool own_req;
223
-
224
-	req->num_retrans = 0;
225
-	req->num_timeout = 0;
226
-	req->sk = NULL;
227263 
228264 	child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
229265 							 NULL, &own_req);
....@@ -240,7 +276,7 @@
240276 	 */
241277 	tp = tcp_sk(child);
242278 
243
-	tp->fastopen_rsk = req;
279
+	rcu_assign_pointer(tp->fastopen_rsk, req);
244280 	tcp_rsk(req)->tfo_listener = true;
245281 
246282 	/* RFC1323: The window in SYN & SYN/ACK segments is never
....@@ -259,7 +295,7 @@
259295 	refcount_set(&req->rsk_refcnt, 2);
260296 
261297 	/* Now finish processing the fastopen child socket. */
262
-	tcp_init_transfer(child, BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB);
298
+	tcp_init_transfer(child, BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB, skb);
263299 
264300 	tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
265301 
....@@ -276,6 +312,7 @@
276312 static bool tcp_fastopen_queue_check(struct sock *sk)
277313 {
278314 	struct fastopen_queue *fastopenq;
315
+	int max_qlen;
279316 
280317 	/* Make sure the listener has enabled fastopen, and we don't
281318 	 * exceed the max # of pending TFO requests allowed before trying
....@@ -288,10 +325,11 @@
288325 	 * temporarily vs a server not supporting Fast Open at all.
289326 	 */
290327 	fastopenq = &inet_csk(sk)->icsk_accept_queue.fastopenq;
291
-	if (fastopenq->max_qlen == 0)
328
+	max_qlen = READ_ONCE(fastopenq->max_qlen);
329
+	if (max_qlen == 0)
292330 		return false;
293331 
294
-	if (fastopenq->qlen >= fastopenq->max_qlen) {
332
+	if (fastopenq->qlen >= max_qlen) {
295333 		struct request_sock *req1;
296334 		spin_lock(&fastopenq->lock);
297335 		req1 = fastopenq->rskq_rst_head;
....@@ -313,7 +351,7 @@
313351 				   const struct dst_entry *dst,
314352 				   int flag)
315353 {
316
-	return (sock_net(sk)->ipv4.sysctl_tcp_fastopen & flag) ||
354
+	return (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fastopen) & flag) ||
317355 	       tcp_sk(sk)->fastopen_no_cookie ||
318356 	       (dst && dst_metric(dst, RTAX_FASTOPEN_NO_COOKIE));
319357 }
....@@ -328,9 +366,10 @@
328366 			      const struct dst_entry *dst)
329367 {
330368 	bool syn_data = TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1;
331
-	int tcp_fastopen = sock_net(sk)->ipv4.sysctl_tcp_fastopen;
369
+	int tcp_fastopen = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fastopen);
332370 	struct tcp_fastopen_cookie valid_foc = { .len = -1 };
333371 	struct sock *child;
372
+	int ret = 0;
334373 
335374 	if (foc->len == 0) /* Client requests a cookie */
336375 		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENCOOKIEREQD);
....@@ -345,31 +384,44 @@
345384 	if (tcp_fastopen_no_cookie(sk, dst, TFO_SERVER_COOKIE_NOT_REQD))
346385 		goto fastopen;
347386 
348
-	if (foc->len >= 0 &&  /* Client presents or requests a cookie */
349
-	    tcp_fastopen_cookie_gen(sk, req, skb, &valid_foc) &&
350
-	    foc->len == TCP_FASTOPEN_COOKIE_SIZE &&
351
-	    foc->len == valid_foc.len &&
352
-	    !memcmp(foc->val, valid_foc.val, foc->len)) {
353
-		/* Cookie is valid. Create a (full) child socket to accept
354
-		 * the data in SYN before returning a SYN-ACK to ack the
355
-		 * data. If we fail to create the socket, fall back and
356
-		 * ack the ISN only but includes the same cookie.
357
-		 *
358
-		 * Note: Data-less SYN with valid cookie is allowed to send
359
-		 * data in SYN_RECV state.
360
-		 */
361
-fastopen:
362
-		child = tcp_fastopen_create_child(sk, skb, req);
363
-		if (child) {
364
-			foc->len = -1;
387
+	if (foc->len == 0) {
388
+		/* Client requests a cookie. */
389
+		tcp_fastopen_cookie_gen(sk, req, skb, &valid_foc);
390
+	} else if (foc->len > 0) {
391
+		ret = tcp_fastopen_cookie_gen_check(sk, req, skb, foc,
392
+						    &valid_foc);
393
+		if (!ret) {
365394 			NET_INC_STATS(sock_net(sk),
366
-				      LINUX_MIB_TCPFASTOPENPASSIVE);
367
-			return child;
395
+				      LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
396
+		} else {
397
+			/* Cookie is valid. Create a (full) child socket to
398
+			 * accept the data in SYN before returning a SYN-ACK to
399
+			 * ack the data. If we fail to create the socket, fall
400
+			 * back and ack the ISN only but includes the same
401
+			 * cookie.
402
+			 *
403
+			 * Note: Data-less SYN with valid cookie is allowed to
404
+			 * send data in SYN_RECV state.
405
+			 */
406
+fastopen:
407
+			child = tcp_fastopen_create_child(sk, skb, req);
408
+			if (child) {
409
+				if (ret == 2) {
410
+					valid_foc.exp = foc->exp;
411
+					*foc = valid_foc;
412
+					NET_INC_STATS(sock_net(sk),
413
+						      LINUX_MIB_TCPFASTOPENPASSIVEALTKEY);
414
+				} else {
415
+					foc->len = -1;
416
+				}
417
+				NET_INC_STATS(sock_net(sk),
418
+					      LINUX_MIB_TCPFASTOPENPASSIVE);
419
+				return child;
420
+			}
421
+			NET_INC_STATS(sock_net(sk),
422
+				      LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
368423 		}
369
-		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
370
-	} else if (foc->len > 0) /* Client presents an invalid cookie */
371
-		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
372
-
424
+	}
373425 	valid_foc.exp = foc->exp;
374426 	*foc = valid_foc;
375427 	return NULL;
....@@ -394,7 +446,10 @@
394446 		cookie->len = -1;
395447 		return true;
396448 	}
397
-	return cookie->len > 0;
449
+	if (cookie->len > 0)
450
+		return true;
451
+	tcp_sk(sk)->fastopen_client_fail = TFO_COOKIE_UNAVAILABLE;
452
+	return false;
398453 }
399454 
400455 /* This function checks if we want to defer sending SYN until the first
....@@ -453,6 +508,9 @@
453508 {
454509 	struct net *net = sock_net(sk);
455510 
511
+	if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fastopen_blackhole_timeout))
512
+		return;
513
+
456514 	/* Paired with READ_ONCE() in tcp_fastopen_active_should_disable() */
457515 	WRITE_ONCE(net->ipv4.tfo_active_disable_stamp, jiffies);
458516 
....@@ -471,11 +529,16 @@
471529  */
472530 bool tcp_fastopen_active_should_disable(struct sock *sk)
473531 {
474
-	unsigned int tfo_bh_timeout = sock_net(sk)->ipv4.sysctl_tcp_fastopen_blackhole_timeout;
475
-	int tfo_da_times = atomic_read(&sock_net(sk)->ipv4.tfo_active_disable_times);
532
+	unsigned int tfo_bh_timeout =
533
+		READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fastopen_blackhole_timeout);
476534 	unsigned long timeout;
535
+	int tfo_da_times;
477536 	int multiplier;
478537 
538
+	if (!tfo_bh_timeout)
539
+		return false;
540
+
541
+	tfo_da_times = atomic_read(&sock_net(sk)->ipv4.tfo_active_disable_times);
479542 	if (!tfo_da_times)
480543 		return false;
481544