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-rw-r--r--include/linux/tcp.h5
-rw-r--r--include/net/tcp.h9
-rw-r--r--net/ipv4/tcp_fastopen.c71
-rw-r--r--net/ipv4/tcp_ipv4.c10
-rw-r--r--net/ipv4/tcp_output.c2
5 files changed, 33 insertions, 64 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 4e37c71ecd74..bc35e4709e8e 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -366,11 +366,6 @@ static inline bool tcp_passive_fastopen(const struct sock *sk)
tcp_sk(sk)->fastopen_rsk != NULL);
}
-static inline bool fastopen_cookie_present(struct tcp_fastopen_cookie *foc)
-{
- return foc->len != -1;
-}
-
extern void tcp_sock_destruct(struct sock *sk);
static inline int fastopen_init_queue(struct sock *sk, int backlog)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 012236838583..17d7c6a3d037 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -220,8 +220,6 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
#define TFO_SERVER_ENABLE 2
#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
-/* Process SYN data but skip cookie validation */
-#define TFO_SERVER_COOKIE_NOT_CHKED 0x100
/* Accept SYN data w/o any cookie option */
#define TFO_SERVER_COOKIE_NOT_REQD 0x200
@@ -230,10 +228,6 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
*/
#define TFO_SERVER_WO_SOCKOPT1 0x400
#define TFO_SERVER_WO_SOCKOPT2 0x800
-/* Always create TFO child sockets on a TFO listener even when
- * cookie/data not present. (For testing purpose!)
- */
-#define TFO_SERVER_ALWAYS 0x1000
extern struct inet_timewait_death_row tcp_death_row;
@@ -1335,8 +1329,7 @@ int tcp_fastopen_create_child(struct sock *sk,
struct request_sock *req);
bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
- struct tcp_fastopen_cookie *foc,
- struct tcp_fastopen_cookie *valid_foc);
+ struct tcp_fastopen_cookie *foc);
void tcp_fastopen_init_key_once(bool publish);
#define TCP_FASTOPEN_KEY_LENGTH 16
diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index 0606c91d9d0b..5a98277b9a82 100644
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -228,59 +228,44 @@ static bool tcp_fastopen_queue_check(struct sock *sk)
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_fastopen_check(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
- struct tcp_fastopen_cookie *foc,
- struct tcp_fastopen_cookie *valid_foc)
+ struct tcp_fastopen_cookie *foc)
{
- bool skip_cookie = false;
-
- if (likely(!fastopen_cookie_present(foc))) {
- /* See include/net/tcp.h for the meaning of these knobs */
- if ((sysctl_tcp_fastopen & TFO_SERVER_ALWAYS) ||
- ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD) &&
- (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1)))
- skip_cookie = true; /* no cookie to validate */
- else
- return false;
- }
- /* A FO option is present; bump the counter. */
- NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVE);
+ 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) == 0 ||
- !tcp_fastopen_queue_check(sk))
+ if (!((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) &&
+ (syn_data || foc->len >= 0) &&
+ tcp_fastopen_queue_check(sk))) {
+ foc->len = -1;
return false;
-
- if (skip_cookie) {
- tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
- return true;
}
- if (foc->len == TCP_FASTOPEN_COOKIE_SIZE) {
- if ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_CHKED) == 0) {
- tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
- ip_hdr(skb)->daddr, valid_foc);
- if ((valid_foc->len != TCP_FASTOPEN_COOKIE_SIZE) ||
- memcmp(&foc->val[0], &valid_foc->val[0],
- TCP_FASTOPEN_COOKIE_SIZE) != 0)
- return false;
- valid_foc->len = -1;
- }
- /* Acknowledge the data received from the peer. */
+ if (syn_data && (sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD))
+ goto fastopen;
+
+ tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
+ ip_hdr(skb)->daddr, &valid_foc);
+
+ if (foc->len == TCP_FASTOPEN_COOKIE_SIZE &&
+ foc->len == valid_foc.len &&
+ !memcmp(foc->val, valid_foc.val, foc->len)) {
+fastopen:
tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+ foc->len = -1;
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVE);
return true;
- } else if (foc->len == 0) { /* Client requesting a cookie */
- tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
- ip_hdr(skb)->daddr, valid_foc);
- NET_INC_STATS_BH(sock_net(sk),
- LINUX_MIB_TCPFASTOPENCOOKIEREQD);
- } else {
- /* Client sent a cookie with wrong size. Treat it
- * the same as invalid and return a valid one.
- */
- tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
- ip_hdr(skb)->daddr, valid_foc);
}
+
+ NET_INC_STATS_BH(sock_net(sk), foc->len ?
+ LINUX_MIB_TCPFASTOPENPASSIVEFAIL :
+ LINUX_MIB_TCPFASTOPENCOOKIEREQD);
+ *foc = valid_foc;
return false;
}
EXPORT_SYMBOL(tcp_fastopen_check);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 032fcaee164a..5ea0949dadfd 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1273,7 +1273,6 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
bool want_cookie = false;
struct flowi4 fl4;
struct tcp_fastopen_cookie foc = { .len = -1 };
- struct tcp_fastopen_cookie valid_foc = { .len = -1 };
struct sk_buff *skb_synack;
int do_fastopen;
@@ -1381,7 +1380,8 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
if (dst == NULL)
goto drop_and_free;
}
- do_fastopen = tcp_fastopen_check(sk, skb, req, &foc, &valid_foc);
+ do_fastopen = !want_cookie &&
+ tcp_fastopen_check(sk, skb, req, &foc);
/* We don't call tcp_v4_send_synack() directly because we need
* to make sure a child socket can be created successfully before
@@ -1394,8 +1394,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
* latter to remove its dependency on the current implementation
* of tcp_v4_send_synack()->tcp_select_initial_window().
*/
- skb_synack = tcp_make_synack(sk, dst, req,
- fastopen_cookie_present(&valid_foc) ? &valid_foc : NULL);
+ skb_synack = tcp_make_synack(sk, dst, req, &foc);
if (skb_synack) {
__tcp_v4_send_check(skb_synack, ireq->ir_loc_addr, ireq->ir_rmt_addr);
@@ -1415,9 +1414,6 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
tcp_rsk(req)->listener = NULL;
/* Add the request_sock to the SYN table */
inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
- if (fastopen_cookie_present(&foc) && foc.len != 0)
- NET_INC_STATS_BH(sock_net(sk),
- LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
} else if (tcp_fastopen_create_child(sk, skb, skb_synack, req))
goto drop_and_release;
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 694711a140d4..b20fc02920f9 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -627,7 +627,7 @@ static unsigned int tcp_synack_options(struct sock *sk,
if (unlikely(!ireq->tstamp_ok))
remaining -= TCPOLEN_SACKPERM_ALIGNED;
}
- if (foc != NULL) {
+ if (foc != NULL && foc->len >= 0) {
u32 need = TCPOLEN_EXP_FASTOPEN_BASE + foc->len;
need = (need + 3) & ~3U; /* Align to 32 bits */
if (remaining >= need) {
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.