@@ -208,7 +208,6 @@ enum
LINUX_MIB_TCPDSACKOFOSENT, /* TCPDSACKOfoSent */
LINUX_MIB_TCPDSACKRECV, /* TCPDSACKRecv */
LINUX_MIB_TCPDSACKOFORECV, /* TCPDSACKOfoRecv */
- LINUX_MIB_TCPABORTONSYN, /* TCPAbortOnSyn */
LINUX_MIB_TCPABORTONDATA, /* TCPAbortOnData */
LINUX_MIB_TCPABORTONCLOSE, /* TCPAbortOnClose */
LINUX_MIB_TCPABORTONMEMORY, /* TCPAbortOnMemory */
@@ -235,6 +234,7 @@ enum
LINUX_MIB_TCPRETRANSFAIL, /* TCPRetransFail */
LINUX_MIB_TCPRCVCOALESCE, /* TCPRcvCoalesce */
LINUX_MIB_TCPCHALLENGEACK, /* TCPChallengeACK */
+ LINUX_MIB_TCPSYNCHALLENGE, /* TCPSYNChallenge */
__LINUX_MIB_MAX
};
@@ -232,7 +232,6 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("TCPDSACKOfoSent", LINUX_MIB_TCPDSACKOFOSENT),
SNMP_MIB_ITEM("TCPDSACKRecv", LINUX_MIB_TCPDSACKRECV),
SNMP_MIB_ITEM("TCPDSACKOfoRecv", LINUX_MIB_TCPDSACKOFORECV),
- SNMP_MIB_ITEM("TCPAbortOnSyn", LINUX_MIB_TCPABORTONSYN),
SNMP_MIB_ITEM("TCPAbortOnData", LINUX_MIB_TCPABORTONDATA),
SNMP_MIB_ITEM("TCPAbortOnClose", LINUX_MIB_TCPABORTONCLOSE),
SNMP_MIB_ITEM("TCPAbortOnMemory", LINUX_MIB_TCPABORTONMEMORY),
@@ -259,6 +258,7 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("TCPRetransFail", LINUX_MIB_TCPRETRANSFAIL),
SNMP_MIB_ITEM("TCPRcvCoalesce", LINUX_MIB_TCPRCVCOALESCE),
SNMP_MIB_ITEM("TCPChallengeACK", LINUX_MIB_TCPCHALLENGEACK),
+ SNMP_MIB_ITEM("TCPSYNChallenge", LINUX_MIB_TCPSYNCHALLENGE),
SNMP_MIB_SENTINEL
};
@@ -5451,8 +5451,8 @@ static void tcp_send_challenge_ack(struct sock *sk)
/* Does PAWS and seqno based validation of an incoming segment, flags will
* play significant role here.
*/
-static int tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
- const struct tcphdr *th, int syn_inerr)
+static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
+ const struct tcphdr *th, int syn_inerr)
{
const u8 *hash_location;
struct tcp_sock *tp = tcp_sk(sk);
@@ -5504,20 +5504,22 @@ static int tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
/* step 3: check security and precedence [ignored] */
- /* step 4: Check for a SYN in window. */
- if (th->syn && !before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) {
+ /* step 4: Check for a SYN
+ * RFC 5691 4.2 : Send a challenge ack
+ */
+ if (th->syn) {
if (syn_inerr)
TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
- NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONSYN);
- tcp_reset(sk);
- return -1;
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNCHALLENGE);
+ tcp_send_challenge_ack(sk);
+ goto discard;
}
- return 1;
+ return true;
discard:
__kfree_skb(skb);
- return 0;
+ return false;
}
/*
@@ -5547,7 +5549,6 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
const struct tcphdr *th, unsigned int len)
{
struct tcp_sock *tp = tcp_sk(sk);
- int res;
/*
* Header prediction.
@@ -5725,9 +5726,8 @@ slow_path:
* Standard slow path.
*/
- res = tcp_validate_incoming(sk, skb, th, 1);
- if (res <= 0)
- return -res;
+ if (!tcp_validate_incoming(sk, skb, th, 1))
+ return 0;
step5:
if (th->ack && tcp_ack(sk, skb, FLAG_SLOWPATH) < 0)
@@ -6045,7 +6045,6 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
struct tcp_sock *tp = tcp_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
int queued = 0;
- int res;
tp->rx_opt.saw_tstamp = 0;
@@ -6100,9 +6099,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
return 0;
}
- res = tcp_validate_incoming(sk, skb, th, 0);
- if (res <= 0)
- return -res;
+ if (!tcp_validate_incoming(sk, skb, th, 0))
+ return 0;
/* step 5: check the ACK field */
if (th->ack) {