@@ -252,26 +252,36 @@ struct tcp_options_received {
sack_ok : 4, /* SACK seen on SYN packet */
snd_wscale : 4, /* Window scaling received from sender */
rcv_wscale : 4; /* Window scaling to send to receiver */
-/* SACKs data */
+ u8 cookie_plus: 6; /* bytes in authenticator/cookie option */
u8 num_sacks; /* Number of SACK blocks */
- u16 user_mss; /* mss requested by user in ioctl */
+ u16 user_mss; /* mss requested by user in ioctl */
u16 mss_clamp; /* Maximal mss, negotiated at connection setup */
};
+static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
+{
+ rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
+ rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
+ rx_opt->cookie_plus = 0;
+}
+
/* This is the max number of SACKS that we'll generate and process. It's safe
* to increse this, although since:
* size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
* only four options will fit in a standard TCP header */
#define TCP_NUM_SACKS 4
+struct tcp_cookie_values;
+struct tcp_request_sock_ops;
+
struct tcp_request_sock {
struct inet_request_sock req;
#ifdef CONFIG_TCP_MD5SIG
/* Only used by TCP MD5 Signature so far. */
const struct tcp_request_sock_ops *af_specific;
#endif
- u32 rcv_isn;
- u32 snt_isn;
+ u32 rcv_isn;
+ u32 snt_isn;
};
static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
@@ -441,6 +451,19 @@ struct tcp_sock {
/* TCP MD5 Signature Option information */
struct tcp_md5sig_info *md5sig_info;
#endif
+
+ /* When the cookie options are generated and exchanged, then this
+ * object holds a reference to them (cookie_values->kref). Also
+ * contains related tcp_cookie_transactions fields.
+ */
+ struct tcp_cookie_values *cookie_values;
+
+ u8 cookie_in_always:1,
+ cookie_out_never:1,
+ extend_timestamp:1,
+ s_data_constant:1,
+ s_data_in:1,
+ s_data_out:1;
};
static inline struct tcp_sock *tcp_sk(const struct sock *sk)
@@ -459,6 +482,10 @@ struct tcp_timewait_sock {
u16 tw_md5_keylen;
u8 tw_md5_key[TCP_MD5SIG_MAXKEYLEN];
#endif
+ /* Few sockets in timewait have cookies; in that case, then this
+ * object holds a reference to it (tw_cookie_values->kref)
+ */
+ struct tcp_cookie_values *tw_cookie_values;
};
static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
@@ -30,6 +30,7 @@
#include <linux/dmaengine.h>
#include <linux/crypto.h>
#include <linux/cryptohash.h>
+#include <linux/kref.h>
#include <net/inet_connection_sock.h>
#include <net/inet_timewait_sock.h>
@@ -167,6 +168,7 @@ extern void tcp_time_wait(struct sock *sk, int state, int timeo);
#define TCPOPT_SACK 5 /* SACK Block */
#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
+#define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */
/*
* TCP option lengths
@@ -177,6 +179,10 @@ extern void tcp_time_wait(struct sock *sk, int state, int timeo);
#define TCPOLEN_SACK_PERM 2
#define TCPOLEN_TIMESTAMP 10
#define TCPOLEN_MD5SIG 18
+#define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
+#define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
+#define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
+#define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
/* But this is what stacks really send out. */
#define TCPOLEN_TSTAMP_ALIGNED 12
@@ -344,11 +350,6 @@ static inline void tcp_dec_quickack_mode(struct sock *sk,
extern void tcp_enter_quickack_mode(struct sock *sk);
-static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
-{
- rx_opt->tstamp_ok = rx_opt->sack_ok = rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
-}
-
#define TCP_ECN_OK 1
#define TCP_ECN_QUEUE_CWR 2
#define TCP_ECN_DEMAND_CWR 4
@@ -410,7 +411,7 @@ extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk,
extern void tcp_parse_options(struct sk_buff *skb,
struct tcp_options_received *opt_rx,
- int estab);
+ u8 **cryptic, int estab);
extern u8 *tcp_parse_md5sig_option(struct tcphdr *th);
@@ -1482,6 +1483,65 @@ struct tcp_request_sock_ops {
#endif
};
+/**
+ * A tcp_sock contains a pointer to the current value, and this is cloned to
+ * the tcp_timewait_sock.
+ *
+ * @cookie_pair: variable data from the option exchange.
+ *
+ * @cookie_desired: user specified tcpct_cookie_desired. Zero
+ * indicates default (sysctl_tcp_cookie_size).
+ * After cookie sent, remembers size of cookie.
+ *
+ * @s_data_desired: user specified tcpct_s_data_desired. When the
+ * constant payload is specified (s_data_constant),
+ * holds its length instead.
+ *
+ * @s_data_payload: constant data that is to be included in the
+ * payload of SYN or SYNACK segments when the
+ * cookie option is present.
+ */
+struct tcp_cookie_values {
+ struct kref kref;
+ u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
+ u8 cookie_pair_size;
+ u8 cookie_desired;
+ u16 s_data_desired;
+ u8 s_data_payload[0];
+};
+
+static inline void tcp_cookie_values_release(struct kref *kref)
+{
+ kfree(container_of(kref, struct tcp_cookie_values, kref));
+}
+
+/* The length of constant payload data. Note that s_data_desired is
+ * overloaded, depending on s_data_constant: either the length of constant
+ * data (returned here) or the limit on variable data.
+ */
+static inline int tcp_s_data_size(const struct tcp_sock *tp)
+{
+ return (NULL != tp->cookie_values && tp->s_data_constant)
+ ? tp->cookie_values->s_data_desired
+ : 0;
+}
+
+/* As tcp_request_sock has already been extended in other places, the
+ * only remaining method is to pass stack values along as function
+ * parameters. These parameters are not needed after sending SYNACK.
+ */
+struct tcp_extend_values {
+ u8 cookie_bakery[TCP_COOKIE_MAX];
+ u8 cookie_plus;
+ u8 cookie_in_always:1,
+ cookie_out_never:1;
+};
+
+static inline struct tcp_extend_values *tcp_xv(const void *extend_values)
+{
+ return (struct tcp_extend_values *)extend_values;
+}
+
extern void tcp_v4_init(void);
extern void tcp_init(void);
@@ -253,6 +253,8 @@ EXPORT_SYMBOL(cookie_check_timestamp);
struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
struct ip_options *opt)
{
+ struct tcp_options_received tcp_opt;
+ u8 *cryptic_value;
struct inet_request_sock *ireq;
struct tcp_request_sock *treq;
struct tcp_sock *tp = tcp_sk(sk);
@@ -263,7 +265,6 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
int mss;
struct rtable *rt;
__u8 rcv_wscale;
- struct tcp_options_received tcp_opt;
if (!sysctl_tcp_syncookies || !th->ack)
goto out;
@@ -278,7 +279,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
/* check for timestamp cookie support */
memset(&tcp_opt, 0, sizeof(tcp_opt));
- tcp_parse_options(skb, &tcp_opt, 0);
+ tcp_parse_options(skb, &tcp_opt, &cryptic_value, 0);
if (tcp_opt.saw_tstamp)
cookie_check_timestamp(&tcp_opt);
@@ -2039,8 +2039,8 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
int val;
int err = 0;
- /* This is a string value all the others are int's */
- if (optname == TCP_CONGESTION) {
+ /* These are data/string values, all the others are ints */
+ if (TCP_CONGESTION == optname) {
char name[TCP_CA_NAME_MAX];
if (optlen < 1)
@@ -2056,6 +2056,95 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
err = tcp_set_congestion_control(sk, name);
release_sock(sk);
return err;
+ } else if (TCP_COOKIE_TRANSACTIONS == optname) {
+ struct tcp_cookie_transactions ctd;
+ struct tcp_cookie_values *cvp = NULL;
+
+ if (sizeof(ctd) > optlen) {
+ return -EINVAL;
+ }
+ if (copy_from_user(&ctd, optval, sizeof(ctd))) {
+ return -EFAULT;
+ }
+ if (sizeof(ctd.tcpct_value) < ctd.tcpct_used) {
+ return -EINVAL;
+ }
+ if (0 == ctd.tcpct_cookie_desired) {
+ /* default to global value */
+ } else if ((0x1 & ctd.tcpct_cookie_desired)
+ || TCP_COOKIE_MAX < ctd.tcpct_cookie_desired
+ || TCP_COOKIE_MIN > ctd.tcpct_cookie_desired) {
+ return -EINVAL;
+ }
+
+ if (TCP_COOKIE_OUT_NEVER & ctd.tcpct_flags) {
+ /* Supercedes all other values */
+ lock_sock(sk);
+ if (NULL != tp->cookie_values) {
+ kref_put(&tp->cookie_values->kref,
+ tcp_cookie_values_release);
+ tp->cookie_values = NULL;
+ }
+ tp->cookie_in_always = 0; /* false */
+ tp->cookie_out_never = 1; /* true */
+ tp->extend_timestamp = 0; /* false */
+ tp->s_data_constant = 0; /* false */
+ tp->s_data_in = 0; /* false */
+ tp->s_data_out = 0; /* false */
+ release_sock(sk);
+ return err;
+ }
+
+ /* Allocate ancillary memory before locking.
+ */
+ if (0 < ctd.tcpct_used
+ || (NULL == tp->cookie_values
+ && (0 < sysctl_tcp_cookie_size
+ || 0 < ctd.tcpct_cookie_desired
+ || 0 < ctd.tcpct_s_data_desired))) {
+ cvp = kmalloc(sizeof(*cvp) + ctd.tcpct_used,
+ GFP_KERNEL);
+ if (NULL == cvp) {
+ return -ENOMEM;
+ }
+ }
+
+ lock_sock(sk);
+ tp->cookie_in_always = (TCP_COOKIE_IN_ALWAYS & ctd.tcpct_flags);
+ tp->cookie_out_never = 0; /* false */
+ tp->extend_timestamp = (TCP_EXTEND_TIMESTAMP & ctd.tcpct_flags);
+ tp->s_data_in = 0; /* false */
+ tp->s_data_out = 0; /* false */
+
+ if (NULL == cvp) {
+ /* No cookies by default. */
+ tp->s_data_constant = 0; /* false */
+ } else if (0 == ctd.tcpct_used) {
+ /* No constant payload data. */
+ cvp->cookie_desired = ctd.tcpct_cookie_desired;
+ cvp->s_data_desired = ctd.tcpct_s_data_desired;
+ tp->cookie_values = cvp;
+ tp->s_data_constant = 0; /* false */
+ } else {
+ /* Changes in values are recorded by a change in
+ * pointer, ensuring that the cookie will differ,
+ * without separately hashing each value later.
+ */
+ if (unlikely(NULL != tp->cookie_values)) {
+ kref_put(&tp->cookie_values->kref,
+ tcp_cookie_values_release);
+ }
+ kref_init(&cvp->kref);
+ memcpy(cvp->s_data_payload, ctd.tcpct_value,
+ ctd.tcpct_used);
+ cvp->cookie_desired = ctd.tcpct_cookie_desired;
+ cvp->s_data_desired = ctd.tcpct_used;
+ tp->cookie_values = cvp;
+ tp->s_data_constant = 1; /* true */
+ }
+
+ release_sock(sk);
+ return err;
}
if (optlen < sizeof(int))
@@ -2387,6 +2476,46 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
if (copy_to_user(optval, icsk->icsk_ca_ops->name, len))
return -EFAULT;
return 0;
+
+ case TCP_COOKIE_TRANSACTIONS: {
+ struct tcp_cookie_transactions ctd;
+ struct tcp_cookie_values *cvp = tp->cookie_values;
+
+ if (get_user(len, optlen))
+ return -EFAULT;
+ if (len < sizeof(ctd))
+ return -EINVAL;
+
+ memset(&ctd, 0, sizeof(ctd));
+ ctd.tcpct_flags =
+ (tp->cookie_in_always ? TCP_COOKIE_IN_ALWAYS : 0)
+ | (tp->cookie_out_never ? TCP_COOKIE_OUT_NEVER : 0)
+ | (tp->extend_timestamp ? TCP_EXTEND_TIMESTAMP : 0)
+ | (tp->s_data_in ? TCP_S_DATA_IN : 0)
+ | (tp->s_data_out ? TCP_S_DATA_OUT : 0);
+
+ if (NULL != cvp) {
+ /* Cookie(s) saved, return as nonce */
+ if (sizeof(ctd.tcpct_value) < cvp->cookie_pair_size) {
+ /* impossible? */
+ return -EINVAL;
+ }
+ memcpy(&ctd.tcpct_value[0], &cvp->cookie_pair[0],
+ cvp->cookie_pair_size);
+ ctd.tcpct_used = cvp->cookie_pair_size;
+
+ ctd.tcpct_cookie_desired = cvp->cookie_desired;
+ ctd.tcpct_s_data_desired = cvp->s_data_desired;
+ }
+
+ if (copy_to_user(optval, &ctd, sizeof(ctd))) {
+ return -EFAULT;
+ }
+ if (put_user(sizeof(ctd), optlen)) {
+ return -EFAULT;
+ }
+ return 0;
+ }
default:
return -ENOPROTOOPT;
}
@@ -3698,11 +3698,11 @@ old_ack:
* the fast version below fails.
*/
void tcp_parse_options(struct sk_buff *skb, struct tcp_options_received *opt_rx,
- int estab)
+ u8 **cryptic, int estab)
{
unsigned char *ptr;
struct tcphdr *th = tcp_hdr(skb);
- int length = (th->doff * 4) - sizeof(struct tcphdr);
+ int length = tcp_option_len_th(th);
ptr = (unsigned char *)(th + 1);
opt_rx->saw_tstamp = 0;
@@ -3782,6 +3782,19 @@ void tcp_parse_options(struct sk_buff *skb, struct tcp_options_received *opt_rx,
*/
break;
#endif
+ case TCPOPT_COOKIE:
+ /* This option carries 3 different lengths.
+ */
+ if (TCPOLEN_COOKIE_MAX >= opsize
+ && TCPOLEN_COOKIE_MIN <= opsize) {
+ opt_rx->cookie_plus = opsize;
+ *cryptic = ptr;
+ } else if (TCPOLEN_COOKIE_PAIR == opsize) {
+ /* not yet implemented */
+ } else if (TCPOLEN_COOKIE_BASE == opsize) {
+ /* not yet implemented */
+ }
+ break;
}
ptr += opsize-2;
@@ -3810,17 +3823,21 @@ static int tcp_parse_aligned_timestamp(struct tcp_sock *tp, struct tcphdr *th)
* If it is wrong it falls back on tcp_parse_options().
*/
static int tcp_fast_parse_options(struct sk_buff *skb, struct tcphdr *th,
- struct tcp_sock *tp)
+ struct tcp_sock *tp, u8 **cryptic)
{
- if (th->doff == sizeof(struct tcphdr) >> 2) {
+ /* In the spirit of fast parsing, compare doff directly to shifted
+ * constant values. Because equality is used, short doff can be
+ * ignored here, and checked later.
+ */
+ if ((sizeof(*th) >> 2) == th->doff) {
tp->rx_opt.saw_tstamp = 0;
return 0;
} else if (tp->rx_opt.tstamp_ok &&
- th->doff == (sizeof(struct tcphdr)>>2)+(TCPOLEN_TSTAMP_ALIGNED>>2)) {
+ ((sizeof(*th)+TCPOLEN_TSTAMP_ALIGNED)>>2) == th->doff) {
if (tcp_parse_aligned_timestamp(tp, th))
return 1;
}
- tcp_parse_options(skb, &tp->rx_opt, 1);
+ tcp_parse_options(skb, &tp->rx_opt, cryptic, 1);
return 1;
}
@@ -3830,7 +3847,7 @@ static int tcp_fast_parse_options(struct sk_buff *skb, struct tcphdr *th,
*/
u8 *tcp_parse_md5sig_option(struct tcphdr *th)
{
- int length = (th->doff << 2) - sizeof (*th);
+ int length = tcp_option_len_th(th);
u8 *ptr = (u8*)(th + 1);
/* If the TCP option is too short, we can short cut */
@@ -5070,10 +5087,11 @@ out:
static int tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
struct tcphdr *th, int syn_inerr)
{
+ u8 *cv;
struct tcp_sock *tp = tcp_sk(sk);
/* RFC1323: H1. Apply PAWS check first. */
- if (tcp_fast_parse_options(skb, th, tp) && tp->rx_opt.saw_tstamp &&
+ if (tcp_fast_parse_options(skb, th, tp, &cv) && tp->rx_opt.saw_tstamp &&
tcp_paws_discard(sk, skb)) {
if (!th->rst) {
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSESTABREJECTED);
@@ -5361,11 +5379,14 @@ discard:
static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
struct tcphdr *th, unsigned len)
{
- struct tcp_sock *tp = tcp_sk(sk);
+ u8 *cryptic_value;
struct inet_connection_sock *icsk = inet_csk(sk);
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct tcp_cookie_values *cvp = tp->cookie_values;
int saved_clamp = tp->rx_opt.mss_clamp;
+ int queued = 0;
- tcp_parse_options(skb, &tp->rx_opt, 0);
+ tcp_parse_options(skb, &tp->rx_opt, &cryptic_value, 0);
if (th->ack) {
/* rfc793:
@@ -5462,6 +5483,42 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
* Change state from SYN-SENT only after copied_seq
* is initialized. */
tp->copied_seq = tp->rcv_nxt;
+
+ if (NULL != cvp
+ && 0 < cvp->cookie_pair_size
+ && 0 < tp->rx_opt.cookie_plus) {
+ int cookie_size = tp->rx_opt.cookie_plus - TCPOLEN_COOKIE_BASE;
+ int cookie_pair_size = cvp->cookie_desired + cookie_size;
+
+ /* A cookie extension option was sent and returned.
+ * Note that each incoming SYNACK replaces the
+ * Responder cookie. The initial exchange is most
+ * fragile, as protection against spoofing relies
+ * entirely upon the sequence and timestamp (above).
+ * This replacement strategy allows the correct pair to
+ * pass through, while any others will be filtered via
+ * Responder verification later.
+ */
+ if (sizeof(cvp->cookie_pair) >= cookie_pair_size) {
+ memcpy(&cvp->cookie_pair[cvp->cookie_desired],
+ cryptic_value, cookie_size);
+ cvp->cookie_pair_size = cookie_pair_size;
+ }
+
+ if (tcp_header_len_th(th) < skb->len) {
+ /* Queue incoming transaction data. */
+ __skb_pull(skb, tcp_header_len_th(th));
+ __skb_queue_tail(&sk->sk_receive_queue, skb);
+ skb_set_owner_r(skb, sk);
+ sk->sk_data_ready(sk, 0);
+ tp->s_data_in = 1; /* true */
+ queued = 1; /* should be amount? */
+ tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+ tp->rcv_wup = TCP_SKB_CB(skb)->end_seq;
+ tp->copied_seq = TCP_SKB_CB(skb)->seq + 1;
+ }
+ }
+
smp_mb();
tcp_set_state(sk, TCP_ESTABLISHED);
@@ -5513,11 +5570,14 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
TCP_DELACK_MAX, TCP_RTO_MAX);
discard:
- __kfree_skb(skb);
+ if (0 == queued)
+ __kfree_skb(skb);
return 0;
} else {
tcp_send_ack(sk);
}
+ if (0 < queued)
+ return 0; /* amount queued? */
return -1;
}
@@ -217,7 +217,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
if (inet->opt)
inet_csk(sk)->icsk_ext_hdr_len = inet->opt->optlen;
- tp->rx_opt.mss_clamp = 536;
+ tp->rx_opt.mss_clamp = TCP_MIN_RCVMSS;
/* Socket identity is still unknown (sport may be zero).
* However we set state to SYN-SENT and not releasing socket
@@ -1211,9 +1211,12 @@ static struct timewait_sock_ops tcp_timewait_sock_ops = {
int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
{
- struct inet_request_sock *ireq;
+ struct tcp_extend_values tmp_ext;
struct tcp_options_received tmp_opt;
+ u8 *cryptic_value;
+ struct inet_request_sock *ireq;
struct request_sock *req;
+ struct tcp_sock *tp = tcp_sk(sk);
__be32 saddr = ip_hdr(skb)->saddr;
__be32 daddr = ip_hdr(skb)->daddr;
__u32 isn = TCP_SKB_CB(skb)->when;
@@ -1258,16 +1261,37 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
#endif
tcp_clear_options(&tmp_opt);
- tmp_opt.mss_clamp = 536;
- tmp_opt.user_mss = tcp_sk(sk)->rx_opt.user_mss;
+ tmp_opt.mss_clamp = TCP_MIN_RCVMSS;
+ tmp_opt.user_mss = tp->rx_opt.user_mss;
- tcp_parse_options(skb, &tmp_opt, 0);
+ tcp_parse_options(skb, &tmp_opt, &cryptic_value, 0);
+
+ if (0 < tmp_opt.cookie_plus
+ && tmp_opt.saw_tstamp
+ && !tp->cookie_out_never
+ && (0 < sysctl_tcp_cookie_size
+ || (NULL != tp->cookie_values
+ && 0 < tp->cookie_values->cookie_desired))) {
+#ifdef CONFIG_SYN_COOKIES
+ want_cookie = 0; /* not our kind of cookie */
+#endif
+ tmp_ext.cookie_out_never = 0; /* false */
+ tmp_ext.cookie_plus = tmp_opt.cookie_plus;
+
+ /* secret recipe not yet implemented */
+ } else if (!tp->cookie_in_always) {
+ /* redundant indications, but ensure initialization. */
+ tmp_ext.cookie_out_never = 1; /* true */
+ tmp_ext.cookie_plus = 0;
+ } else {
+ goto drop_and_free;
+ }
+ tmp_ext.cookie_in_always = tp->cookie_in_always;
if (want_cookie && !tmp_opt.saw_tstamp)
tcp_clear_options(&tmp_opt);
tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
-
tcp_openreq_init(req, &tmp_opt, skb);
ireq = inet_rsk(req);
@@ -1334,7 +1358,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
}
tcp_rsk(req)->snt_isn = isn;
- if (__tcp_v4_send_synack(sk, req, dst, NULL) ||
+ if (__tcp_v4_send_synack(sk, req, dst, (void *)&tmp_ext) ||
want_cookie)
goto drop_and_free;
@@ -1812,7 +1836,7 @@ static int tcp_v4_init_sock(struct sock *sk)
*/
tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
tp->snd_cwnd_clamp = ~0;
- tp->mss_cache = 536;
+ tp->mss_cache = TCP_MIN_RCVMSS;
tp->reordering = sysctl_tcp_reordering;
icsk->icsk_ca_ops = &tcp_init_congestion_ops;
@@ -1828,6 +1852,19 @@ static int tcp_v4_init_sock(struct sock *sk)
tp->af_specific = &tcp_sock_ipv4_specific;
#endif
+ /* TCP Cookie Transactions */
+ if (0 < sysctl_tcp_cookie_size) {
+ /* Default, cookies without s_data. */
+ tp->cookie_values =
+ kzalloc(sizeof(*tp->cookie_values), sk->sk_allocation);
+ if (NULL != tp->cookie_values) {
+ kref_init(&tp->cookie_values->kref);
+ }
+ }
+ /* Presumed zeroed, in order of appearance:
+ * cookie_in_always, cookie_out_never, extend_timestamp,
+ * s_data_constant, s_data_in, s_data_out
+ */
sk->sk_sndbuf = sysctl_tcp_wmem[1];
sk->sk_rcvbuf = sysctl_tcp_rmem[1];
@@ -1881,6 +1918,15 @@ void tcp_v4_destroy_sock(struct sock *sk)
sk->sk_sndmsg_page = NULL;
}
+ /*
+ * If cookie or s_data exists, remove it.
+ */
+ if (NULL != tp->cookie_values) {
+ kref_put(&tp->cookie_values->kref,
+ tcp_cookie_values_release);
+ tp->cookie_values = NULL;
+ }
+
percpu_counter_dec(&tcp_sockets_allocated);
}
@@ -96,13 +96,14 @@ enum tcp_tw_status
tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
const struct tcphdr *th)
{
- struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
struct tcp_options_received tmp_opt;
+ u8 *cryptic_value;
+ struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
int paws_reject = 0;
tmp_opt.saw_tstamp = 0;
if (th->doff > (sizeof(*th) >> 2) && tcptw->tw_ts_recent_stamp) {
- tcp_parse_options(skb, &tmp_opt, 0);
+ tcp_parse_options(skb, &tmp_opt, &cryptic_value, 0);
if (tmp_opt.saw_tstamp) {
tmp_opt.ts_recent = tcptw->tw_ts_recent;
@@ -394,9 +395,12 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
/* Now setup tcp_sock */
newtp = tcp_sk(newsk);
newtp->pred_flags = 0;
- newtp->rcv_wup = newtp->copied_seq = newtp->rcv_nxt = treq->rcv_isn + 1;
- newtp->snd_sml = newtp->snd_una = newtp->snd_nxt = treq->snt_isn + 1;
- newtp->snd_up = treq->snt_isn + 1;
+
+ newtp->rcv_wup = newtp->copied_seq =
+ newtp->rcv_nxt = treq->rcv_isn + 1;
+
+ newtp->snd_sml = newtp->snd_una = newtp->snd_nxt =
+ newtp->snd_up = treq->snt_isn + 1 + tcp_s_data_size(tcp_sk(sk));
tcp_prequeue_init(newtp);
@@ -429,9 +433,24 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
tcp_set_ca_state(newsk, TCP_CA_Open);
tcp_init_xmit_timers(newsk);
skb_queue_head_init(&newtp->out_of_order_queue);
- newtp->write_seq = treq->snt_isn + 1;
- newtp->pushed_seq = newtp->write_seq;
+ newtp->write_seq = newtp->pushed_seq =
+ treq->snt_isn + 1 + tcp_s_data_size(tcp_sk(sk));
+ /* TCP Cookie Transactions */
+ if (NULL != tcp_sk(sk)->cookie_values) {
+ /* Instead of reusing the original, replace with
+ * default, cookies without s_data.
+ */
+ newtp->cookie_values =
+ kzalloc(sizeof(*newtp->cookie_values), GFP_ATOMIC);
+ if (NULL != newtp->cookie_values) {
+ kref_init(&newtp->cookie_values->kref);
+ }
+ }
+ /* Presumed copied, in order of appearance:
+ * cookie_in_always, cookie_out_never, extend_timestamp,
+ * s_data_constant, s_data_in, s_data_out
+ */
newtp->rx_opt.saw_tstamp = 0;
newtp->rx_opt.dsack = 0;
@@ -495,15 +514,16 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
struct request_sock **prev)
{
+ struct tcp_options_received tmp_opt;
+ u8 *cryptic_value;
const struct tcphdr *th = tcp_hdr(skb);
__be32 flg = tcp_flag_word(th) & (TCP_FLAG_RST|TCP_FLAG_SYN|TCP_FLAG_ACK);
int paws_reject = 0;
- struct tcp_options_received tmp_opt;
struct sock *child;
tmp_opt.saw_tstamp = 0;
- if (th->doff > (sizeof(struct tcphdr)>>2)) {
- tcp_parse_options(skb, &tmp_opt, 0);
+ if (th->doff > (sizeof(*th) >> 2)) {
+ tcp_parse_options(skb, &tmp_opt, &cryptic_value, 0);
if (tmp_opt.saw_tstamp) {
tmp_opt.ts_recent = req->ts_recent;
@@ -596,7 +616,8 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
* Invalid ACK: reset will be sent by listening socket
*/
if ((flg & TCP_FLAG_ACK) &&
- (TCP_SKB_CB(skb)->ack_seq != tcp_rsk(req)->snt_isn + 1))
+ (TCP_SKB_CB(skb)->ack_seq != tcp_rsk(req)->snt_isn + 1 +
+ tcp_s_data_size(tcp_sk(sk))))
return sk;
/* Also, it would be not so bad idea to check rcv_tsecr, which
@@ -370,6 +370,7 @@ static inline int tcp_urg_mode(const struct tcp_sock *tp)
#define OPTION_TS (1 << 1)
#define OPTION_MD5 (1 << 2)
#define OPTION_WSCALE (1 << 3)
+#define OPTION_COOKIE_EXTENSION (1 << 4)
struct tcp_out_options {
u8 options; /* bit field of OPTION_* */
@@ -377,8 +378,35 @@ struct tcp_out_options {
u8 num_sack_blocks; /* number of SACK blocks to include */
u16 mss; /* 0 to disable */
__u32 tsval, tsecr; /* need to include OPTION_TS */
+ u8 *cookie_copy; /* temporary pointer */
+ u8 cookie_size; /* bytes in copy */
};
+/* The sysctl int routines are generic, so check consistency here.
+ */
+static u8 tcp_cookie_size_check(u8 desired)
+{
+ if (0 < desired) {
+ /* previously specified */
+ return desired;
+ }
+ if (0 >= sysctl_tcp_cookie_size) {
+ /* no default specified */
+ return 0;
+ }
+ if (TCP_COOKIE_MIN > sysctl_tcp_cookie_size) {
+ return TCP_COOKIE_MIN;
+ }
+ if (TCP_COOKIE_MAX < sysctl_tcp_cookie_size) {
+ return TCP_COOKIE_MAX;
+ }
+ if (0x1 & sysctl_tcp_cookie_size) {
+ /* 8-bit multiple, illegal, fix it */
+ return (u8)(sysctl_tcp_cookie_size + 0x1);
+ }
+ return (u8)sysctl_tcp_cookie_size;
+}
+
/* Write previously computed TCP options to the packet.
*
* Beware: Something in the Internet is very sensitive to the ordering of
@@ -395,11 +423,22 @@ struct tcp_out_options {
static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
const struct tcp_out_options *opts,
__u8 **md5_hash) {
- if (unlikely(OPTION_MD5 & opts->options)) {
- *ptr++ = htonl((TCPOPT_NOP << 24) |
- (TCPOPT_NOP << 16) |
- (TCPOPT_MD5SIG << 8) |
- TCPOLEN_MD5SIG);
+ u8 options = opts->options; /* mungable copy */
+
+ if (unlikely(OPTION_MD5 & options)) {
+ if (unlikely(OPTION_COOKIE_EXTENSION & options)) {
+ *ptr++ = htonl((TCPOPT_COOKIE << 24) |
+ (TCPOLEN_COOKIE_BASE << 16) |
+ (TCPOPT_MD5SIG << 8) |
+ TCPOLEN_MD5SIG);
+ } else {
+ *ptr++ = htonl((TCPOPT_NOP << 24) |
+ (TCPOPT_NOP << 16) |
+ (TCPOPT_MD5SIG << 8) |
+ TCPOLEN_MD5SIG);
+ }
+ /* larger cookies are incompatible */
+ options &= ~OPTION_COOKIE_EXTENSION;
*md5_hash = (__u8 *)ptr;
ptr += 4;
} else {
@@ -412,12 +451,13 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
opts->mss);
}
- if (likely(OPTION_TS & opts->options)) {
- if (unlikely(OPTION_SACK_ADVERTISE & opts->options)) {
+ if (likely(OPTION_TS & options)) {
+ if (unlikely(OPTION_SACK_ADVERTISE & options)) {
*ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
(TCPOLEN_SACK_PERM << 16) |
(TCPOPT_TIMESTAMP << 8) |
TCPOLEN_TIMESTAMP);
+ options &= ~OPTION_SACK_ADVERTISE;
} else {
*ptr++ = htonl((TCPOPT_NOP << 24) |
(TCPOPT_NOP << 16) |
@@ -428,15 +468,48 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
*ptr++ = htonl(opts->tsecr);
}
- if (unlikely(OPTION_SACK_ADVERTISE & opts->options &&
- !(OPTION_TS & opts->options))) {
+ /* Specification requires after timestamp, so do it now.
+ */
+ if (unlikely(OPTION_COOKIE_EXTENSION & options)) {
+ u8 *cookie_copy = opts->cookie_copy;
+ u8 cookie_size = opts->cookie_size;
+
+ if (unlikely(0x1 & cookie_size)) {
+ /* 8-bit multiple, illegal, ignore */
+ cookie_size = 0;
+ } else if (likely(0x2 & cookie_size)) {
+ __u8 *p = (__u8 *)ptr;
+
+ /* 16-bit multiple */
+ *p++ = TCPOPT_COOKIE;
+ *p++ = TCPOLEN_COOKIE_BASE + cookie_size;
+ *p++ = *cookie_copy++;
+ *p++ = *cookie_copy++;
+ ptr++;
+ cookie_size -= 2;
+ } else {
+ /* 32-bit multiple */
+ *ptr++ = htonl(((TCPOPT_NOP << 24) |
+ (TCPOPT_NOP << 16) |
+ (TCPOPT_COOKIE << 8) |
+ TCPOLEN_COOKIE_BASE) +
+ cookie_size);
+ }
+
+ if (0 < cookie_size) {
+ memcpy(ptr, cookie_copy, cookie_size);
+ ptr += (cookie_size >> 2);
+ }
+ }
+
+ if (unlikely(OPTION_SACK_ADVERTISE & options)) {
*ptr++ = htonl((TCPOPT_NOP << 24) |
(TCPOPT_NOP << 16) |
(TCPOPT_SACK_PERM << 8) |
TCPOLEN_SACK_PERM);
}
- if (unlikely(OPTION_WSCALE & opts->options)) {
+ if (unlikely(OPTION_WSCALE & options)) {
*ptr++ = htonl((TCPOPT_NOP << 24) |
(TCPOPT_WINDOW << 16) |
(TCPOLEN_WINDOW << 8) |
@@ -471,11 +544,18 @@ static unsigned tcp_syn_options(struct sock *sk, struct sk_buff *skb,
struct tcp_out_options *opts,
struct tcp_md5sig_key **md5) {
struct tcp_sock *tp = tcp_sk(sk);
+ struct tcp_cookie_values *cvp = tp->cookie_values;
unsigned size = 0;
+ u8 cookie_size = (!tp->cookie_out_never && NULL != cvp)
+ ? tcp_cookie_size_check(cvp->cookie_desired)
+ : 0;
#ifdef CONFIG_TCP_MD5SIG
*md5 = tp->af_specific->md5_lookup(sk, sk);
if (*md5) {
+ if (0 < cookie_size) {
+ opts->options |= OPTION_COOKIE_EXTENSION;
+ }
opts->options |= OPTION_MD5;
size += TCPOLEN_MD5SIG_ALIGNED;
}
@@ -512,6 +592,63 @@ static unsigned tcp_syn_options(struct sock *sk, struct sk_buff *skb,
size += TCPOLEN_SACKPERM_ALIGNED;
}
+ /* Having both authentication and cookies for security is redundant,
+ * and there's certainly not enough room. Instead, the cookie-less
+ * variant is proposed above.
+ *
+ * Consider the pessimal case with authentication. The options
+ * could look like:
+ * COOKIE|MD5(20) + MSS(4) + WSCALE(4) + SACK|TS(12) == 40
+ *
+ * (Currently, the timestamps && *MD5 test above prevents this.)
+ *
+ * Note that timestamps are required by the specification.
+ *
+ * Odd numbers of bytes are prohibited by the specification, ensuring
+ * that the cookie is 16-bit aligned, and the resulting cookie pair is
+ * 32-bit aligned.
+ */
+ if (NULL == *md5
+ && (OPTION_TS & opts->options)
+ && 0 < cookie_size) {
+ int need = TCPOLEN_COOKIE_BASE + cookie_size;
+ int remaining = MAX_TCP_OPTION_SPACE - size;
+
+ if (0x2 & need) {
+ /* 32-bit multiple */
+ need += 2; /* NOPs */
+
+ if (need > remaining) {
+ /* try shrinking cookie to fit */
+ cookie_size -= 2;
+ need -= 4;
+ }
+ }
+ while (need > remaining && TCP_COOKIE_MIN <= cookie_size) {
+ cookie_size -= 4;
+ need -= 4;
+ }
+ if (TCP_COOKIE_MIN <= cookie_size) {
+ opts->options |= OPTION_COOKIE_EXTENSION;
+ opts->cookie_copy = &cvp->cookie_pair[0];
+ opts->cookie_size = cookie_size;
+
+ /* Remember for future incarnations. */
+ cvp->cookie_desired = cookie_size;
+
+ if (cvp->cookie_desired != cvp->cookie_pair_size) {
+ /* Currently use random bytes as a nonce,
+ * assuming these are completely unpredictable
+ * by hostile users of the same system.
+ */
+ get_random_bytes(opts->cookie_copy,
+ cookie_size);
+ cvp->cookie_pair_size = cookie_size;
+ }
+
+ size += need;
+ }
+ }
return size;
}
@@ -520,14 +657,22 @@ static unsigned tcp_synack_options(struct sock *sk,
struct request_sock *req,
unsigned mss, struct sk_buff *skb,
struct tcp_out_options *opts,
- struct tcp_md5sig_key **md5) {
- unsigned size = 0;
+ struct tcp_md5sig_key **md5,
+ struct tcp_extend_values *xvp)
+{
struct inet_request_sock *ireq = inet_rsk(req);
+ unsigned size = 0;
+ u8 cookie_plus = (NULL != xvp && !xvp->cookie_out_never)
+ ? xvp->cookie_plus
+ : 0;
char doing_ts;
#ifdef CONFIG_TCP_MD5SIG
*md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req);
if (*md5) {
+ if (0 < cookie_plus) {
+ opts->options |= OPTION_COOKIE_EXTENSION;
+ }
opts->options |= OPTION_MD5;
size += TCPOLEN_MD5SIG_ALIGNED;
}
@@ -561,6 +706,34 @@ static unsigned tcp_synack_options(struct sock *sk,
size += TCPOLEN_SACKPERM_ALIGNED;
}
+ /* Similar rationale to tcp_syn_options() applies here, too.
+ * If the <SYN> options fit, the same options should fit now!
+ */
+ if (NULL == *md5
+ && doing_ts
+ && 0 < cookie_plus) {
+ int need = cookie_plus; /* has TCPOLEN_COOKIE_BASE */
+ int remaining = MAX_TCP_OPTION_SPACE - size;
+
+ if (0x2 & need) {
+ /* 32-bit multiple */
+ need += 2; /* NOPs */
+ }
+ if (need <= remaining) {
+ opts->options |= OPTION_COOKIE_EXTENSION;
+ opts->cookie_copy = &xvp->cookie_bakery[0];
+ opts->cookie_size = cookie_plus - TCPOLEN_COOKIE_BASE;
+
+ /* secret recipe not yet implemented */
+ get_random_bytes(opts->cookie_copy,
+ opts->cookie_size);
+
+ size += need;
+ } else {
+ /* There's no error return, so flag it. */
+ xvp->cookie_out_never = 1; /* true */
+ }
+ }
return size;
}
@@ -2229,14 +2402,15 @@ int tcp_send_synack(struct sock *sk)
struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
struct request_sock *req, void *extend_values)
{
+ struct tcp_out_options opts;
+ struct tcp_extend_values *xvp = tcp_xv(extend_values);
struct inet_request_sock *ireq = inet_rsk(req);
struct tcp_sock *tp = tcp_sk(sk);
struct tcphdr *th;
- int tcp_header_size;
- struct tcp_out_options opts;
struct sk_buff *skb;
struct tcp_md5sig_key *md5;
__u8 *md5_hash_location;
+ int tcp_header_size;
int mss;
skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15, 1, GFP_ATOMIC);
@@ -2274,7 +2448,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
#endif
TCP_SKB_CB(skb)->when = tcp_time_stamp;
tcp_header_size = tcp_synack_options(sk, req, mss,
- skb, &opts, &md5) +
+ skb, &opts, &md5, xvp) +
sizeof(struct tcphdr);
skb_push(skb, tcp_header_size);
@@ -2292,6 +2466,25 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
*/
tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn,
TCPCB_FLAG_SYN | TCPCB_FLAG_ACK);
+
+ /* If cookies are active, and constant data is available, copy it
+ * directly from the listening socket.
+ */
+ if (NULL != xvp
+ && !xvp->cookie_out_never
+ && 0 < xvp->cookie_plus
+ && tp->s_data_constant) {
+ const struct tcp_cookie_values *cvp = tp->cookie_values;
+
+ if (NULL != cvp
+ && 0 < cvp->s_data_desired) {
+ u8 *buf = skb_put(skb, cvp->s_data_desired);
+
+ memcpy(buf, cvp->s_data_payload, cvp->s_data_desired);
+ TCP_SKB_CB(skb)->end_seq += cvp->s_data_desired;
+ }
+ }
+
th->seq = htonl(TCP_SKB_CB(skb)->seq);
th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1);
@@ -159,6 +159,8 @@ static inline int cookie_check(struct sk_buff *skb, __u32 cookie)
struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
{
+ struct tcp_options_received tcp_opt;
+ u8 *cryptic_value;
struct inet_request_sock *ireq;
struct inet6_request_sock *ireq6;
struct tcp_request_sock *treq;
@@ -171,7 +173,6 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
int mss;
struct dst_entry *dst;
__u8 rcv_wscale;
- struct tcp_options_received tcp_opt;
if (!sysctl_tcp_syncookies || !th->ack)
goto out;
@@ -186,7 +187,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
/* check for timestamp cookie support */
memset(&tcp_opt, 0, sizeof(tcp_opt));
- tcp_parse_options(skb, &tcp_opt, 0);
+ tcp_parse_options(skb, &tcp_opt, &cryptic_value, 0);
if (tcp_opt.saw_tstamp)
cookie_check_timestamp(&tcp_opt);
@@ -1161,11 +1161,13 @@ static struct sock *tcp_v6_hnd_req(struct sock *sk,struct sk_buff *skb)
*/
static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
{
+ struct tcp_extend_values tmp_ext;
+ struct tcp_options_received tmp_opt;
+ u8 *cryptic_value;
struct inet6_request_sock *treq;
struct ipv6_pinfo *np = inet6_sk(sk);
- struct tcp_options_received tmp_opt;
- struct tcp_sock *tp = tcp_sk(sk);
struct request_sock *req = NULL;
+ struct tcp_sock *tp = tcp_sk(sk);
__u32 isn = TCP_SKB_CB(skb)->when;
#ifdef CONFIG_SYN_COOKIES
int want_cookie = 0;
@@ -1205,7 +1207,29 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
tmp_opt.mss_clamp = IPV6_MIN_MTU - sizeof(struct tcphdr) - sizeof(struct ipv6hdr);
tmp_opt.user_mss = tp->rx_opt.user_mss;
- tcp_parse_options(skb, &tmp_opt, 0);
+ tcp_parse_options(skb, &tmp_opt, &cryptic_value, 0);
+
+ if (0 < tmp_opt.cookie_plus
+ && tmp_opt.saw_tstamp
+ && !tp->cookie_out_never
+ && (0 < sysctl_tcp_cookie_size
+ || (NULL != tp->cookie_values
+ && 0 < tp->cookie_values->cookie_desired))) {
+#ifdef CONFIG_SYN_COOKIES
+ want_cookie = 0; /* not our kind of cookie */
+#endif
+ tmp_ext.cookie_out_never = 0; /* false */
+ tmp_ext.cookie_plus = tmp_opt.cookie_plus;
+
+ /* secret recipe not yet implemented */
+ } else if (!tp->cookie_in_always) {
+ /* redundant indications, but ensure initialization. */
+ tmp_ext.cookie_out_never = 1; /* true */
+ tmp_ext.cookie_plus = 0;
+ } else {
+ goto drop;
+ }
+ tmp_ext.cookie_in_always = tp->cookie_in_always;
if (want_cookie && !tmp_opt.saw_tstamp)
tcp_clear_options(&tmp_opt);
@@ -1243,7 +1267,7 @@ static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
security_inet_conn_request(sk, skb, req);
- if (tcp_v6_send_synack(sk, req, NULL) ||
+ if (tcp_v6_send_synack(sk, req, (void *)&tmp_ext) ||
want_cookie)
goto drop;
@@ -1848,7 +1872,7 @@ static int tcp_v6_init_sock(struct sock *sk)
*/
tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
tp->snd_cwnd_clamp = ~0;
- tp->mss_cache = 536;
+ tp->mss_cache = TCP_MIN_RCVMSS;
tp->reordering = sysctl_tcp_reordering;
@@ -1864,6 +1888,19 @@ static int tcp_v6_init_sock(struct sock *sk)
tp->af_specific = &tcp_sock_ipv6_specific;
#endif
+ /* TCP Cookie Transactions */
+ if (0 < sysctl_tcp_cookie_size) {
+ /* Default, cookies without s_data. */
+ tp->cookie_values =
+ kzalloc(sizeof(*tp->cookie_values), sk->sk_allocation);
+ if (NULL != tp->cookie_values) {
+ kref_init(&tp->cookie_values->kref);
+ }
+ }
+ /* Presumed zeroed, in order of appearance:
+ * cookie_in_always, cookie_out_never, extend_timestamp,
+ * s_data_constant, s_data_in, s_data_out
+ */
sk->sk_sndbuf = sysctl_tcp_wmem[1];
sk->sk_rcvbuf = sysctl_tcp_rmem[1];