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-rw-r--r--include/net/tcp.h9
-rw-r--r--net/ipv4/syncookies.c79
-rw-r--r--net/ipv4/tcp_input.c25
-rw-r--r--net/ipv4/tcp_output.c13
-rw-r--r--net/ipv6/syncookies.c5
5 files changed, 87 insertions, 44 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 3a35b1500359..f50f29faf76f 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -490,17 +490,16 @@ u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
u16 *mssp);
__u32 cookie_v4_init_sequence(struct sock *sk, const struct sk_buff *skb,
__u16 *mss);
-#endif
-
__u32 cookie_init_timestamp(struct request_sock *req);
-bool cookie_check_timestamp(struct tcp_options_received *opt, struct net *net,
- bool *ecn_ok);
+bool cookie_timestamp_decode(struct tcp_options_received *opt);
+bool cookie_ecn_ok(const struct tcp_options_received *opt,
+ const struct net *net, const struct dst_entry *dst);
/* From net/ipv6/syncookies.c */
int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th,
u32 cookie);
struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
-#ifdef CONFIG_SYN_COOKIES
+
u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
const struct tcphdr *th, u16 *mssp);
__u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 4ac7bcaf2f46..45fe60c5238e 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -19,10 +19,6 @@
#include <net/tcp.h>
#include <net/route.h>
-/* Timestamps: lowest bits store TCP options */
-#define TSBITS 6
-#define TSMASK (((__u32)1 << TSBITS) - 1)
-
extern int sysctl_tcp_syncookies;
static u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS] __read_mostly;
@@ -30,6 +26,30 @@ static u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS] __read_mostly;
#define COOKIEBITS 24 /* Upper bits store count */
#define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
+/* TCP Timestamp: 6 lowest bits of timestamp sent in the cookie SYN-ACK
+ * stores TCP options:
+ *
+ * MSB LSB
+ * | 31 ... 6 | 5 | 4 | 3 2 1 0 |
+ * | Timestamp | ECN | SACK | WScale |
+ *
+ * When we receive a valid cookie-ACK, we look at the echoed tsval (if
+ * any) to figure out which TCP options we should use for the rebuilt
+ * connection.
+ *
+ * A WScale setting of '0xf' (which is an invalid scaling value)
+ * means that original syn did not include the TCP window scaling option.
+ */
+#define TS_OPT_WSCALE_MASK 0xf
+#define TS_OPT_SACK BIT(4)
+#define TS_OPT_ECN BIT(5)
+/* There is no TS_OPT_TIMESTAMP:
+ * if ACK contains timestamp option, we already know it was
+ * requested/supported by the syn/synack exchange.
+ */
+#define TSBITS 6
+#define TSMASK (((__u32)1 << TSBITS) - 1)
+
static DEFINE_PER_CPU(__u32 [16 + 5 + SHA_WORKSPACE_WORDS],
ipv4_cookie_scratch);
@@ -67,9 +87,11 @@ __u32 cookie_init_timestamp(struct request_sock *req)
ireq = inet_rsk(req);
- options = ireq->wscale_ok ? ireq->snd_wscale : 0xf;
- options |= ireq->sack_ok << 4;
- options |= ireq->ecn_ok << 5;
+ options = ireq->wscale_ok ? ireq->snd_wscale : TS_OPT_WSCALE_MASK;
+ if (ireq->sack_ok)
+ options |= TS_OPT_SACK;
+ if (ireq->ecn_ok)
+ options |= TS_OPT_ECN;
ts = ts_now & ~TSMASK;
ts |= options;
@@ -219,16 +241,13 @@ static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
* additional tcp options in the timestamp.
* This extracts these options from the timestamp echo.
*
- * The lowest 4 bits store snd_wscale.
- * next 2 bits indicate SACK and ECN support.
- *
- * return false if we decode an option that should not be.
+ * return false if we decode a tcp option that is disabled
+ * on the host.
*/
-bool cookie_check_timestamp(struct tcp_options_received *tcp_opt,
- struct net *net, bool *ecn_ok)
+bool cookie_timestamp_decode(struct tcp_options_received *tcp_opt)
{
/* echoed timestamp, lowest bits contain options */
- u32 options = tcp_opt->rcv_tsecr & TSMASK;
+ u32 options = tcp_opt->rcv_tsecr;
if (!tcp_opt->saw_tstamp) {
tcp_clear_options(tcp_opt);
@@ -238,22 +257,35 @@ bool cookie_check_timestamp(struct tcp_options_received *tcp_opt,
if (!sysctl_tcp_timestamps)
return false;
- tcp_opt->sack_ok = (options & (1 << 4)) ? TCP_SACK_SEEN : 0;
- *ecn_ok = (options >> 5) & 1;
- if (*ecn_ok && !net->ipv4.sysctl_tcp_ecn)
- return false;
+ tcp_opt->sack_ok = (options & TS_OPT_SACK) ? TCP_SACK_SEEN : 0;
if (tcp_opt->sack_ok && !sysctl_tcp_sack)
return false;
- if ((options & 0xf) == 0xf)
+ if ((options & TS_OPT_WSCALE_MASK) == TS_OPT_WSCALE_MASK)
return true; /* no window scaling */
tcp_opt->wscale_ok = 1;
- tcp_opt->snd_wscale = options & 0xf;
+ tcp_opt->snd_wscale = options & TS_OPT_WSCALE_MASK;
+
return sysctl_tcp_window_scaling != 0;
}
-EXPORT_SYMBOL(cookie_check_timestamp);
+EXPORT_SYMBOL(cookie_timestamp_decode);
+
+bool cookie_ecn_ok(const struct tcp_options_received *tcp_opt,
+ const struct net *net, const struct dst_entry *dst)
+{
+ bool ecn_ok = tcp_opt->rcv_tsecr & TS_OPT_ECN;
+
+ if (!ecn_ok)
+ return false;
+
+ if (net->ipv4.sysctl_tcp_ecn)
+ return true;
+
+ return dst_feature(dst, RTAX_FEATURE_ECN);
+}
+EXPORT_SYMBOL(cookie_ecn_ok);
struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
{
@@ -269,7 +301,6 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
int mss;
struct rtable *rt;
__u8 rcv_wscale;
- bool ecn_ok = false;
struct flowi4 fl4;
if (!sysctl_tcp_syncookies || !th->ack || th->rst)
@@ -290,7 +321,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
memset(&tcp_opt, 0, sizeof(tcp_opt));
tcp_parse_options(skb, &tcp_opt, 0, NULL);
- if (!cookie_check_timestamp(&tcp_opt, sock_net(sk), &ecn_ok))
+ if (!cookie_timestamp_decode(&tcp_opt))
goto out;
ret = NULL;
@@ -308,7 +339,6 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
ireq->ir_loc_addr = ip_hdr(skb)->daddr;
ireq->ir_rmt_addr = ip_hdr(skb)->saddr;
ireq->ir_mark = inet_request_mark(sk, skb);
- ireq->ecn_ok = ecn_ok;
ireq->snd_wscale = tcp_opt.snd_wscale;
ireq->sack_ok = tcp_opt.sack_ok;
ireq->wscale_ok = tcp_opt.wscale_ok;
@@ -357,6 +387,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
dst_metric(&rt->dst, RTAX_INITRWND));
ireq->rcv_wscale = rcv_wscale;
+ ireq->ecn_ok = cookie_ecn_ok(&tcp_opt, sock_net(sk), &rt->dst);
ret = get_cookie_sock(sk, skb, req, &rt->dst);
/* ip_queue_xmit() depends on our flow being setup
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 4e4617e90417..196b4388116c 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5876,20 +5876,22 @@ static inline void pr_drop_req(struct request_sock *req, __u16 port, int family)
*/
static void tcp_ecn_create_request(struct request_sock *req,
const struct sk_buff *skb,
- const struct sock *listen_sk)
+ const struct sock *listen_sk,
+ const struct dst_entry *dst)
{
const struct tcphdr *th = tcp_hdr(skb);
const struct net *net = sock_net(listen_sk);
bool th_ecn = th->ece && th->cwr;
- bool ect, need_ecn;
+ bool ect, need_ecn, ecn_ok;
if (!th_ecn)
return;
ect = !INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield);
need_ecn = tcp_ca_needs_ecn(listen_sk);
+ ecn_ok = net->ipv4.sysctl_tcp_ecn || dst_feature(dst, RTAX_FEATURE_ECN);
- if (!ect && !need_ecn && net->ipv4.sysctl_tcp_ecn)
+ if (!ect && !need_ecn && ecn_ok)
inet_rsk(req)->ecn_ok = 1;
else if (ect && need_ecn)
inet_rsk(req)->ecn_ok = 1;
@@ -5954,13 +5956,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
if (security_inet_conn_request(sk, skb, req))
goto drop_and_free;
- if (!want_cookie || tmp_opt.tstamp_ok)
- tcp_ecn_create_request(req, skb, sk);
-
- if (want_cookie) {
- isn = cookie_init_sequence(af_ops, sk, skb, &req->mss);
- req->cookie_ts = tmp_opt.tstamp_ok;
- } else if (!isn) {
+ if (!want_cookie && !isn) {
/* VJ's idea. We save last timestamp seen
* from the destination in peer table, when entering
* state TIME-WAIT, and check against it before
@@ -6008,6 +6004,15 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
goto drop_and_free;
}
+ tcp_ecn_create_request(req, skb, sk, dst);
+
+ if (want_cookie) {
+ isn = cookie_init_sequence(af_ops, sk, skb, &req->mss);
+ req->cookie_ts = tmp_opt.tstamp_ok;
+ if (!tmp_opt.tstamp_ok)
+ inet_rsk(req)->ecn_ok = 0;
+ }
+
tcp_rsk(req)->snt_isn = isn;
tcp_openreq_init_rwin(req, sk, dst);
fastopen = !want_cookie &&
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index a3d453b94747..0b88158dd4a7 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -333,10 +333,19 @@ static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb)
static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
+ bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 ||
+ tcp_ca_needs_ecn(sk);
+
+ if (!use_ecn) {
+ const struct dst_entry *dst = __sk_dst_get(sk);
+
+ if (dst && dst_feature(dst, RTAX_FEATURE_ECN))
+ use_ecn = true;
+ }
tp->ecn_flags = 0;
- if (sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 ||
- tcp_ca_needs_ecn(sk)) {
+
+ if (use_ecn) {
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR;
tp->ecn_flags = TCP_ECN_OK;
if (tcp_ca_needs_ecn(sk))
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index be291baa2ec2..7337fc7947e2 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -166,7 +166,6 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
int mss;
struct dst_entry *dst;
__u8 rcv_wscale;
- bool ecn_ok = false;
if (!sysctl_tcp_syncookies || !th->ack || th->rst)
goto out;
@@ -186,7 +185,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
memset(&tcp_opt, 0, sizeof(tcp_opt));
tcp_parse_options(skb, &tcp_opt, 0, NULL);
- if (!cookie_check_timestamp(&tcp_opt, sock_net(sk), &ecn_ok))
+ if (!cookie_timestamp_decode(&tcp_opt))
goto out;
ret = NULL;
@@ -223,7 +222,6 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
req->expires = 0UL;
req->num_retrans = 0;
- ireq->ecn_ok = ecn_ok;
ireq->snd_wscale = tcp_opt.snd_wscale;
ireq->sack_ok = tcp_opt.sack_ok;
ireq->wscale_ok = tcp_opt.wscale_ok;
@@ -264,6 +262,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
dst_metric(dst, RTAX_INITRWND));
ireq->rcv_wscale = rcv_wscale;
+ ireq->ecn_ok = cookie_ecn_ok(&tcp_opt, sock_net(sk), dst);
ret = get_cookie_sock(sk, skb, req, dst);
out: